Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations

The following discussion should be read in conjunction with the attached financial statements and notes thereto. This Annual Report on Form 10-K, including the following sections, contains forward-looking statements within the meaning of the federal securities laws. These statements are subject to risks and uncertainties that could cause actual results and events to differ materially from those expressed or implied by such forward-looking statements. For a detailed discussion of these risks and uncertainties, see the “Risk Factors” section in Item 1A of this Annual Report on Form 10-K. We caution the reader not to place undue reliance on these forward-looking statements, which reflect management’s analysis only as of the date of this Form 10-K. We undertake no obligation to update forward-looking statements, which reflect events or circumstances occurring after the date of this Form 10-K.

Overview

We are a clinical stage drug discovery, development and manufacturing company focused on deploying our proprietary integrated cell-free protein synthesis platform, XpressCF®, and our site specific conjugation platform, XpressCF+®TM, to create a broad variety of optimally designed, next-generation protein therapeutics, initially for cancer. We aim to design therapeutics using the most relevant and potent modalities, including cytokine-based therapeutics, immuno-oncology, or I/O agents, antibody-drug conjugates, or ADCs, immunostimulatory ADCs, or iADCs, and bispecific antibodies that are directed primarily against clinically validated targets where the current standard of care is suboptimal. We believe our platform allows us to accelerate the discovery and development of potential first-in-class and best-in-class molecules by enabling the rapid and systematic evaluation of protein structure-activity relationships to create optimized homogeneous product candidates. Our mission is to transform the lives of patients by using our XpressCF® platform to create medicines with improved therapeutic profiles for areas of unmet need.

Once identified, production of protein drug candidates can be rapidly and predictably scaled in our current Good Manufacturing Practices compliant manufacturing facility. We have the ability to manufacture our cell-free extract that supports our production of proteins on a large scale using a semi-continuous fermentation process. Our two most advanced product candidates are wholly owned: STRO-002, an ADC directed against folate receptor-alpha, or FolRα, for patients with FolRα-expressing cancers, such as ovarian and endometrial cancers, and STRO-001, an ADC directed against CD74, for patients with B-cell malignancies, such as multiple myeloma and non-Hodgkin lymphoma, or NHL.

STRO-002 was designed and optimized for an improved therapeutic index by placing a precise number of linker-warheads at four specific locations within the antibody using our proprietary XpressCF+®TM platform. Our first Phase 1 trial for STRO-002 is an open-label study evaluating STRO-002 as a monotherapy for patients with ovarian and endometrial cancers. This trial is being conducted in two-parts, dose escalation and dose expansion. The primary objectives of the STRO-002 clinical trial are to determine the safety and tolerability profile, to define the recommended Phase 2 dose level and interval and to evaluate preliminary anti-tumor activity. Our secondary objectives are to characterize the human pharmacokinetics and additional safety, tolerability and efficacy measures.

We are developing STRO-001, an optimally designed ADC directed against the cancer target CD74, for multiple myeloma and NHL. STRO-001 was designed and optimized for maximal therapeutic index by placing linker-warheads at specific locations within the antibody using our proprietary XpressCF+®TM platform. The Phase 1 trial for STRO-001 is an open-label study that is evaluating STRO-001 as a monotherapy for patients with multiple myeloma and NHL. The trial is being conducted in two parts: dose escalation and dose expansion. The primary objectives of the trial are to determine the safety and tolerability profile of STRO-001, determine the recommended Phase 2 dose and interval and evaluate preliminary anti-tumor activity. The secondary objectives are to characterize the human pharmacokinetics of STRO-001 and additional safety, tolerability and efficacy measures.

In March 2019, STRO-002 began enrolling patients in a Phase 1 trial focused on ovarian and endometrial cancers. The dose escalation portion of the STRO-002 Phase 1 trial has been completed and the dose expansion portion of the trial is ongoing to assess the efficacy, safety and tolerability of STRO-002 at dose levels of 4.3 and 5.2 mg/kg. In May 2021, we reported data from the dose-escalation cohort. Based on such reported data, STRO-002 exhibited a manageable safety profile and promising preliminary efficacy data, as discussed in more detail in Item 1 of Part I “Business” of this document. In January 2022, we released initial results of the dose expansion

portion of the STRO-002 Phase 1 trial. These data suggested that STRO-002 exhibited a manageable safety profile together with promising preliminary efficacy data in the tested patient population, as discussed in more detail in Item 1 of Part I “Business” of this document. In August 2021, we were granted Fast Track designation for STRO-002 by the FDA for the treatment of patients with platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer who have received one to three prior lines of systemic therapy. In December 2021, we entered into a licensing agreement with Tasly Biopharmaceuticals Co., Ltd, or Tasly, to grant Tasly an exclusive license to develop and commercialize STRO-002 in China, Hong Kong, Macau and Taiwan, referred to as Greater China, or the Tasly License Agreement.

Our second candidate, STRO-001, is currently enrolling patients in a Phase 1 trial, with updated data reported in December 2020, as discussed in more detail in Item 1 of Part I “Business” of this document. Based on such reported data, STRO-001 has been generally well-tolerated and, unlike certain other ADCs, no ocular toxicity signals have been observed, with no patients receiving prophylactic corticosteroid eye drops. Dose escalation in the STRO-001 Phase 1 trial is continuing, and the maximum tolerated dose has not yet been reached. In October 2018, we were granted Orphan Drug Designation by the FDA for STRO-001 for the treatment of multiple myeloma. In October 2021, we granted BioNova Pharmaceuticals Limited, or BioNova, an option to exclusively license the right to develop and commercialize STRO-001 in Greater China, or the BioNova Option Agreement.

Based on our proprietary XpressCF® and XpressCF+®TM platforms, we have also entered into multi-target, product-focused collaborations with leaders in the field of oncology, including a cytokine derivatives collaboration with Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, or Merck; a B Cell Maturation Antigen, or BCMA, ADC collaboration with Celgene Corporation, or Celgene, a wholly owned subsidiary of Bristol-Myers Squibb Company, New York, NY, or BMS; a MUC1-EGFR ADC collaboration with Merck KGaA, Darmstadt Germany (operating in the United States and Canada under the name “EMD Serono”); and license agreement to develop and commercialize STRO-002 in Greater China with Tasly. Our XpressCF® and XpressCF+®TM platforms have also supported a spin-out company, Vaxcyte Inc., or Vaxcyte, focused on discovery and development of vaccines for the treatment and prophylaxis of infectious disease.

Since the commencement of our operations, we have devoted substantially all of our resources to performing research and development and manufacturing activities in support of our own product development efforts and those of our collaborators, raising capital to support and expand such activities and providing general and administrative support for these operations. We have funded our operations to date primarily from upfront, milestone and other payments under our collaboration agreements with BMS, Merck and EMD Serono, the issuance and sale of redeemable convertible preferred stock, our initial public offering, or IPO, follow-on public offerings of common stock and debt proceeds.

We do not have any products approved for commercial sale and have not generated any revenue from commercial product sales. We had a loss from operations of $98.5 million and a net loss of $105.5 million for the year ended December 31, 2021, which net loss included the non-operating, unrealized loss of $4.5 million related to our holdings of Vaxcyte common stock. We had a loss from operations of $71.1 million and net loss of $32.1 million, due principally to an unrealized gain of $41.5 million related to our holdings of Vaxcyte common stock, for the year ended December 31, 2020. Substantially all of our losses have resulted from expenses incurred in connection with our research and development programs and from general and administrative costs associated with our operations. We cannot assure you that we will have net income or that we will generate positive cash flow from operating activities in the future. As of December 31, 2021, we had an accumulated deficit of $333.4 million. We do not expect to generate any revenue from commercial product sales unless and until we successfully complete development and obtain regulatory approval for one or more of our product candidates, which we expect will take a number of years. If we obtain regulatory approval for any of our product candidates, we expect to incur significant commercialization expenses related to product sales, marketing, manufacturing and distribution. We expect our operating expenses to significantly increase as we continue to develop, and seek regulatory approvals for, our product candidates, engage in other research and development activities, expand our pipeline of product candidates, continue to develop our manufacturing facility and capabilities, maintain and expand our intellectual property portfolio, seek regulatory and marketing approval for any product candidates that we may develop, acquire or in-license other assets or technologies, ultimately establish a sales, marketing and distribution infrastructure to commercialize any products for which we may obtain marketing approval, and operate as a public company. Our net losses may fluctuate significantly from quarter-to-quarter and year-to-year, depending on the timing of our clinical trials, our expenditures on other research and development activities and the timing of achievement and receipt of upfront, milestones and other collaboration agreement payments.

Impacts of the COVID-19 Pandemic

The extent of the impact of COVID-19 on our operational and financial performance will depend on certain developments, including the duration and spread of the pandemic, impacts on our clinical studies, employee or industry events, and effects on our collaboration partners, suppliers, service providers and manufacturers, all of which are uncertain and cannot be predicted. The COVID-19 pandemic and its adverse effects have become more prevalent in the locations where we, our CROs, suppliers or third-party business partners conduct business. We are experiencing the impact of the COVID-19 pandemic on our business through increased cost and delays in the availability of materials routinely used in biologic therapeutic development and manufacturing, which has the potential to cause delays in our research, development and/or manufacturing activities, but overall patient enrollment and treatment remains on track. Additionally, the COVID-19 pandemic has had, and is expected to continue to have, an adverse impact on our operations, particularly as a result of preventive and precautionary measures that we, other businesses, and governments are taking. We may experience more pronounced and significant disruptions in our operations, liquidity, supply chain, facilities, and clinical trials in the future as well. With respect to our clinical trials, we have experienced minor delays in enrollment and occasional delays in data entry by trial sites, but overall enrollment and treatment remains on track. We may in the future experience more significant delays in enrollment, participant dosing, distribution of clinical trial materials, study monitoring and data analysis that could materially adversely impact our business, results of operations, revenue earned from our collaboration partners, and overall financial performance in future periods. Specifically, we may experience impact from changes in how we and companies worldwide conduct business due to the COVID-19 pandemic, including but not limited to restrictions on travel and in-person meetings, the speed and breadth of mass vaccinations for COVID-19 and the efficacy of such vaccines, delays in site activations and enrollment of clinical trials, prioritization of hospital resources toward pandemic effort, delays in review by the FDA and comparable foreign regulatory agencies, limitations on employee resources that would otherwise be focused on the conduct of our research, preclinical studies, clinical trials and manufacturing operations, including because of sickness of employees or their families, the desire of employees to avoid contact with large groups of people, an increased reliance on working from home or mass transit disruptions, and disruptions in our supply chain for our product candidates. Additionally, increased reliance on remote work by our employees as a result of the COVID-19 pandemic poses incremental increased cybersecurity risks as our employees’ home networks are inherently less secure than our corporate networks. As of the filing date of this Form 10-K, the extent to which the COVID-19 pandemic may impact our financial condition, results of operations or guidance is uncertain. The effect of the COVID-19 pandemic will not be fully reflected in our results of operations and overall financial performance until future periods. See the section titled “Risk Factors” for further discussion of the possible impact of the ongoing COVID-19 pandemic on our business.

A discussion and analysis of our financial condition, results of operations, and cash flows for the year ended December 31, 2019 is included in Item 7 of Part II “Management’s Discussion and Analysis of Financial Condition and Results of Operations” in our Annual Report on Form 10-K for the year ended December 31, 2020 filed with the SEC on March 18, 2021.

Financial Operations Overview

Revenue

We do not have any products approved for commercial sale and have not generated any revenue from commercial product sales. Our total revenue to date has been generated principally from our collaboration and license agreements with BMS, Merck, and EMD Serono, and to a lesser extent, from manufacturing, supply and services and materials we provide to the above collaborators and to Vaxcyte.

We derive revenue from collaboration arrangements, under which we may grant licenses to our collaboration partners to further develop and commercialize our proprietary product candidates. We may also perform research and development activities under the collaboration agreements. Consideration under these contracts generally includes a nonrefundable upfront payment, development, regulatory and commercial milestones and other contingent payments, and royalties based on net sales of approved products. Additionally, the collaborations may provide options for the customer to acquire from us materials and reagents, clinical product supply or additional research and development services under separate agreements. We assess which activities in the collaboration agreements are considered distinct performance obligations that should be accounted for separately. We develop assumptions that require judgement to determine whether the license to our intellectual property is distinct from the research and development services or participation in activities under the collaboration agreements.

At the inception of each agreement, we determine the arrangement transaction price, which includes variable consideration, based on the assessment of the probability of achievement of future milestones and contingent payments and other potential consideration. We recognize revenue over time by measuring our progress towards the complete satisfaction of the relevant performance obligation using an appropriate input or output method based on the nature of the service promised to the customer.

For arrangements that include multiple performance obligations, we allocate the transaction price to the identified performance obligations based on the standalone selling price, or SSP, of each distinct performance obligation. In instances where SSP is not directly observable, we develop assumptions that require judgment to determine the SSP for each performance obligation identified in the contract. These key assumptions may include full-time equivalent, or FTE, personnel effort, estimated costs, discount rates and probabilities of clinical development and regulatory success.

Please see further discussion on the revenue recognition treatment of performance obligations under Critical Accounting Policies and Estimates.

Operating Expenses

Research and Development

Research and development expenses represent costs incurred in performing research, development and manufacturing activities in support of our own product development efforts and those of our collaborators, and include salaries, employee benefits, stock-based compensation, laboratory supplies, outsourced research and development expenses, professional services and allocated facilities-related costs. We expense both internal and external research and development costs as they are incurred. Non-refundable advance payments for services that will be used or rendered for future research and development activities are recorded as prepaid expenses and recognized as expenses as the related services are performed.

We expect our research and development expenses to increase in the future as we advance our product candidates into and through preclinical studies and clinical trials, pursue regulatory approval of our product candidates, expand our pipeline of product candidates and continue to develop our manufacturing facility and capabilities. The process of conducting the necessary preclinical and clinical research to obtain regulatory approval is costly and time consuming. The actual probability of success for our product candidates may be affected by a variety of factors including: the safety and efficacy of our product candidates, early clinical data, investment in our clinical programs, the ability of collaborators to successfully develop our licensed product candidates, competition, manufacturing capability and commercial viability. We may never succeed in achieving regulatory approval for any of our product candidates. As a result of the uncertainties discussed above, we are

unable to determine the duration and completion costs of our research and development projects or when and to what extent we will generate revenue from the commercialization and sale of our product candidates.

The following table summarizes our research and development expenses incurred during the periods indicated. The internal costs include personnel, facility costs and research and scientific related activities associated with our pipeline. The external program costs reflect external costs attributable to our clinical development candidates and preclinical candidates selected for further development. Such expenses include third-party costs for preclinical and clinical studies and research, development and manufacturing services, and other consulting costs.

Year ended December 31,

(in thousands)

Internal costs:

External Program Costs:

Toxicology and translational science 1,227 1,030

Process and product development 314 376

Total research and development expenses $ 104,400 $ 76,961

General and Administrative

Our general and administrative expenses consist primarily of personnel costs, expenses for outside professional services, including legal, human resources, audit, accounting and tax services and allocated facilities-related costs. Personnel costs include salaries, employee benefits and stock-based compensation. We expect to incur additional expenses operating as a public company, including expenses related to compliance with the rules and regulations of the SEC and listing standards applicable to companies listed on the Nasdaq Global Market, additional insurance expenses, investor relations activities and other administrative and professional services. We also expect to increase the size of our administrative function and our general and administrative expenses to support the anticipated growth of our business, as we continue to advance our product candidates into and through the clinic.

Interest Income

Interest income consists primarily of interest earned on our invested funds.

Unrealized Gain (Loss) on Equity Securities

Unrealized gain (loss) on equity securities consists of the remeasurement of our investment in Vaxcyte common stock.

Interest and Other Expense, Net

Interest expense includes interest incurred on our debt and amortization of debt issuance costs including accretion of final payment. Additionally, the Company identified a financing component under the Merck 2018 Agreement and recorded interest expense associated with the upfront payment. Other income (expense) includes changes in values attributable to the arrangement with the Call Option Plan as defined in the notes to our financial statements included elsewhere in this report.

Comparison of the Years Ended December 31, 2021 and 2020

Year ended December 31, Change

(in thousands)

Operating expenses:

Revenue

We have recognized revenue as follows during the periods indicated:

Year Ended December 31, Change

(in thousands)

(1)

Merck was a related party until the closing of our public offering on May 14, 2020.

(2)

Vaxcyte was a related party until the closing of its initial public offering on June 16, 2020.

Total revenue increased by $19.2 million, or 45%, during the year ended December 31, 2021 as compared to the year ended December 31, 2020. This was due primarily to $16.7 million from Merck, primarily related to increased revenue from performance obligations, with full recognition of revenue associated with the contingent third program upon the determination that the related performance obligation had terminated during the first quarter of 2021, and a cumulative catch-up in revenue as a result of the change in transaction price, due to a $15.0 million contingent payment earned in the second quarter of 2021 for the initiation of the first IND-enabling toxicology study under the first program in the collaboration. There was also a $4.1 million increase in contract research and manufacturing activities supporting materials supply. The Merck revenue increases noted above were partially offset by a $2.8 million decrease in research and development services and a $1.2 million decrease related to the financing component associated with the upfront payment. Revenue from Vaxcyte under our supply agreement increased by $2.8 million, partially offset by an overall $0.5 million decrease in revenue from EMD Serono.

Research and Development Expense

Research and development expense increased by $27.4 million, or 36%, during the year ended December 31, 2021 as compared to the year ended December 31, 2020. The increase was due primarily to increases of $11.2million in personnel-related expenses due to higher headcount, $6.3 million in laboratory supplies and production materials-related expenses, $4.8 million in facilities-related expenses, $3.4 million in clinical trial costs, $1.5 million in consulting and outside services, and $0.2 million in equipment and office-related expenses.

General and Administrative Expense

General and administrative expense increased by $19.2 million, or 52%, during the year ended December 31, 2021 as compared to the year ended December 31, 2020. The increase was due primarily to increases of $11.4 million in personnel-related expenses due to higher headcount, $3.2 million in insurance and external services, $3.6 million in facilities-related expenses, and $1.0 million in equipment and office-related expenses.

Interest Income

Interest income decreased by $0.9 million during the year ended December 31, 2021 as compared to the year ended December 31, 2020, due primarily to a $2.3 million decrease in the amortization of premiums on investments, partially offset by an increase of $1.4 million from higher average investment balances in 2021.

Unrealized (Loss) Gain on Equity Securities

Unrealized (loss) on equity securities was $4.5 million during the year ended December 31, 2021 as compared to an unrealized gain of $41.5 million for the year ended December 31, 2020. The unrealized (loss) gain on equity securities in each period was entirely due to the remeasurement of the estimated fair value of our investment in Vaxcyte common stock.

Interest and Other Expense, Net

Interest and other expense, net decreased by $0.9 million during the year ended December 31, 2021 as compared to the year ended December 31, 2020, due primarily to a $1.2 million decrease in interest expense associated with the financing component related to the 2018 Merck Agreement, partially offset by a $0.3 million increase in interest expense related to our outstanding debt.

Liquidity and Capital Resources

Sources of Liquidity

To date, we have incurred significant net losses, and negative cash flows from operations. Our operations have been funded primarily by payments received from our collaborators, and net proceeds from equity sales and debt. As of December 31, 2021, we had $229.5 million in cash, cash equivalents and marketable securities, outstanding debt of $25.1million and an accumulated deficit of $333.4million.

2021 Contingent Payment from Merck

During the year ended December 31, 2021, we earned and received a $15.0 million contingent payment from Merck for the initiation of an IND enabling toxicology study for the first program in our collaboration to develop novel cytokine derivative therapeutics for cancer.

2020 Public Offerings

On May 14, 2020, we closed a public offering of 12,650,000 shares of our common stock at a public offering price of $7.75 per share, which included the exercise in full of the underwriters’ option to purchase 1,650,000 shares of common stock. Our net proceeds from this offering, after deducting underwriting discounts and commissions and other offering expenses, was approximately $91.4 million.

On December 11, 2020, we closed a public offering of 6,900,000 shares of our common stock at a public offering price of $21.00 per share, which included the exercise in full of the underwriters’ option to purchase 900,000 shares of common stock. Our net proceeds from this offering, after deducting underwriting discounts and commissions and other offering expenses, was approximately $135.8 million.

At-The-Market Sales

During the year ended December 31, 2020, we sold an aggregate of 2,614,286 shares of our common stock through our At-the-Market ATM facility, or ATM Facility, pursuant to a sales agreementdated October 4, 2019 with Cowen and Company, LLC, as sales agent. The gross proceeds from these sales were approximately $24.6 million, before deducting fees of approximately $0.8 million, resulting in net proceeds of approximately $23.8 million. During the year ended December 31, 2021, we did not sell any shares under an ATM facility.

Vaxcyte, Inc. Equity Ownership

In June 2020, Vaxcyte closed an initial public offering of its common stock at a price per share of $16.00. The Vaxcyte common stock held by us is measured at fair value at each reporting period based on the closing price of Vaxcyte’s common stock on the last trading day of each reporting period, adjusted for a discount for lack of marketability due to the presence of a lock-up agreement during certain periods in 2020, with any unrealized gains and losses recorded in our statements of operations. The lock-up agreement expired in December 2020. As of December 31, 2021, we held 1,562,879 shares of Vaxcyte common stock with an estimated fair value of $37.2 million.

Term Loan

On February 28, 2020, or the Effective Date, we entered into a loan and security agreement, or the Loan and Security Agreement, with Oxford Finance LLC, or Oxford, as the collateral agent and a lender, and Silicon Valley Bank, as a lender, together with Oxford, the Lenders, pursuant to which the Lenders have agreed to lend us up to an aggregate of $25.0 million, or the Term A Loan. Upon entering into the Loan and Security Agreement, we borrowed $25.0 million from the Lenders, with approximately $9.6 million of such amount applied to the repayment of the outstanding principal, interest and final payment fees owed pursuant to the prior loan and security agreement dated August 4, 2017.

The proceeds from the Term A Loan under the Loan and Security Agreement may be used to satisfy our future working capital needs and to fund our general business requirements. Our obligations under the Loan and Security Agreement are secured by all our assets, other than our intellectual property. We have also agreed not to encumber our intellectual property assets, except as permitted by the Loan and Security Agreement.

The Term A Loan matures on March 1, 2024, or the Maturity Date, and will be interest-only through March 1, 2022, followed by 24 equal monthly payments of principal and interest. The Term A Loan will bear interest at a floating per annum rate equal to the greater of (i) 8.07% or (ii) the sum of (a) the greater of (1) the thirty (30) day U.S. LIBOR rate reported in the Wall Street Journal on the last business day of the month that immediately precedes the month in which the interest will accrue or (2) 1.67%, plus (b) 6.40%.

We will be required to make a final payment of 3.83% of the original principal amount of the Term A Loan drawn, payable on the earlier of (i) the Maturity Date, (ii) the acceleration of the Term A Loan, or (iii) the prepayment of the Term A Loan, or the Final Payment. We may prepay all, but not less than all, of the Term A Loan upon 30 days’ advance written notice to Oxford, provided that we will be obligated to pay a prepayment fee equal to (i) 3.00% of the principal amount of the Term A Loan prepaid on or before the first anniversary of the applicable funding date, or (ii) 2.00% of the principal amount of the Term A Loan prepaid between the first and second anniversary of the applicable funding date, or (iii) 1.00% of the principal amount of the Term A Loan prepaid thereafter, and prior to the Maturity Date, each, a Prepayment Fee.

The Loan and Security Agreement contains customary affirmative and restrictive covenants, including covenants regarding incurrence of additional indebtedness or liens, investments, transactions with affiliates, delivery of financial statements, maintenance of inventory, payment of taxes, maintenance of insurance, protection of intellectual property rights, dispositions of property, business combinations or acquisitions, among other customary covenants. We are also restricted from paying dividends or making other distributions or payments on our capital stock, subject to limited exceptions. The Loan and Security Agreement provides that an event of default will occur if, among other triggers, there occurs any circumstances that could reasonably be expected to result in a material adverse change in our business, or operations or condition (financial or otherwise) or a material impairment of the prospect of us to repay any portion of our obligations under the Loan and Security Agreement. The Loan and Security Agreement also includes customary representations and warranties, other events of default and termination provisions.

In connection with entering into the Loan and Security Agreement, we issued to the Lenders warrants exercisable for 81,257 shares of our common stock, or the Debt Warrants. The Debt Warrants are exercisable in whole or in part, immediately, and have a per share exercise price of $9.23, which is the closing price of our common stock reported on the Nasdaq Global Market on the day prior to the Effective Date. The Debt Warrants will terminate on the earlier of February 28, 2030 or the closing of certain merger or consolidation transactions.

Leases

In June 2021, we entered into a third amendment, or Third Amendment, to our manufacturing facility lease, dated May 18, 2011, as amended, by and between Alemany Plaza LLC, located at San Carlos, California, or San Carlos Lease, as an extension to the term of the San Carlos Lease for a period of five years, or the Lease Extension Period. Pursuant to the Third Amendment, the San Carlos Lease will expire on July 31, 2026, and it includes an option to renew the San Carlos Lease for an additional five years. The aggregate estimated base rent payments due over the Lease Extension Period is approximately $4.2 million, subject to certain terms contained in the San Carlos Lease.

In June 2021, we entered into a first amendment, or the First Amendment, to our manufacturing facility lease, dated May 4, 2015, as amended, by and between 870 Industrial Road LLC, located at San Carlos, California, or the Industrial Lease, as an extension to the term of the Industrial Lease for a period of five years, or the Industrial Lease Extension Period. Pursuant to the first Amendment, the Industrial Lease will expire on June 30, 2026, and it includes an option to renew the Industrial Lease for an additional five years. The aggregate estimated base rent payments due over the Industrial Lease Extension Period is approximately $4.3 million, subject to certain terms contained in the Industrial Lease.

In September 2020, the Company entered into a sublease agreement, or the Sublease with Five Prime Therapeutics, Inc., or the Sublessor, for approximately 115,466 square feet, in a building located in South San Francisco, California, or the Premises. The Company uses the Premises as its new corporate headquarters and to conduct (or expand) research and development activities. The Company commenced making monthly payments for the first 85,755 square feet of the Premises, or Initial Premises, in July 2021, with occupancy of such space commencing in August 2021. The Company was provided early access to the Initial Premises in the fourth quarter of 2020 to conduct certain planning and tenant improvement work. The Sublease is subordinate to the lease agreement, effective December 12, 2016, between the Sublessor and HCP Oyster Point III LLC, or the Landlord. The commencement date for the remaining 29,711 square feet of the Premises, or the Expansion Premises, is expected to be 24 months following the commencement date on the Initial Premises. However, the Company has the right to accelerate the commencement date on the Expansion Premises to an earlier date upon six months’ prior written notice to the Sublessor. The Sublease for both the Initial Premises and Expansion Premises will expire on December 31, 2027. With a commencement date on the Initial Premises of July 1, 2021, the aggregate estimated base rent payments due over the term of the Sublease are approximately $39.1 million, including the approximately $5.2 million in potential financial benefit to the Company of base rent abatement to be provided by the Sublessor, subject to certain terms contained in the Sublease. The Sublease contains customary provisions requiring the Company to pay its pro rata share of utilities and a portion of the operating expenses and certain taxes, assessments and fees of the Premises and provisions allowing the Sublessor to terminate the Sublease upon the termination of the lease with the Landlord or if the Company fails to remedy a breach of certain of its obligations within specified time periods. Additionally, the Company posted a security deposit of $0.9 million, which is reflected as restricted cash in non-current assets on the Company’s balance sheet as of December 31, 2021 and 2020.

Funding Requirements

Based upon our current operating plan, we believe that our existing capital resources will enable us to fund our operating expenses and capital expenditure requirements through at least the next twelve months after the date of this filing. We have based this estimate on assumptions that may prove to be wrong, and we could utilize our available capital resources sooner than we currently expect. We will continue to require additional financing to advance our current product candidates into and through clinical development, to develop, acquire or in-license other potential product candidates, pay our obligations and to fund operations for the foreseeable future.

We may seek to raise any necessary additional capital through a combination of public or private equity offerings, debt financings, collaborations, strategic alliances, licensing arrangements, marketing and distribution arrangements, or other sources of financing. Adequate additional funding may not be available to us on acceptable terms, or at all. Any failure to raise capital as and when needed could have a negative impact on our financial condition and on our ability to pursue our business plans and strategies, and may cause us to delay, reduce the scope of or suspend one or more of our pre-clinical and clinical studies, research and development programs or commercialization efforts, and may necessitate us to delay, reduce or terminate planned activities in order to reduce costs. Due to the numerous risks and uncertainties associated with the development and commercialization of our product candidates and the extent to which we may enter into additional collaborations with third parties to participate in their development and commercialization, we are unable to estimate the amounts of increased capital outlays and operating expenditures associated with our current and anticipated clinical studies.

To the extent we raise additional capital through new collaborations, strategic alliances or licensing arrangements with third parties, we may have to relinquish valuable rights to our product candidates, future revenue streams, research programs or product candidates or to grant licenses on terms that may not be favorable to us. If we do raise additional capital through public or private equity or convertible debt offerings, the ownership interest of our existing stockholders will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect our stockholders’ rights. If we raise additional capital through debt financing, we may be subject to covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends.

Cash Flows

The following table summarizes our cash flows during the periods indicated:

Year Ended December 31,

(in thousands)

Cash used in operating activities $ (81,679 ) $ (67,802 )

Cash (used in) provided by investing activities (97,315 ) 604

Cash provided by financing activities 3,256 269,247

Cash Flows from Operating Activities

Cash used in operating activities for the year ended December 31, 2021 was $81.7 million. Our net loss of $105.5 million included $4.5 million of unrealized loss on equity securities as a result of the remeasurement of the estimated fair value of our investment in Vaxcyte common stock, non-cash charges of $23.2 million for stock-based compensation, $4.8 million for depreciation and amortization, $4.9million for noncash lease expenses, $2.8 million for the amortization of premiums on our marketable securities, and $1.2 million in other non-cash charges. Cash used in operating activities also reflected a net change in operating assets and liabilities of $17.6 million, due to an increase of $6.9 million in accounts receivable from our collaborators, a decrease of $15.2 million in our deferred revenue balance from revenue recognized under our collaboration agreements, an increase of $4.0 million in prepaid expenses and other assets, and a decrease of $2.7 million in our operating lease liability, which were partially offset by an increase of $8.6 million in accounts payable and other liabilities due to timing of payments, and an increase of $2.6 million in accrued compensation due to increased headcount.

Cash used in operating activities for the year ended December 31, 2020 was $67.8 million. Our net loss of $32.1 million included $41.5 million of unrealized gain on equity securities as a result of the remeasurement of the estimated fair value of our investment in Vaxcyte common stock, and was partially offset by non-cash charges of $11.9 million for stock-based compensation, $4.3 million for depreciation and amortization, $0.2 million related to revaluation of the vested options under the Call Option Plan, $0.5 million for the amortization of premiums on our marketable securities, and $0.3 million for the amortization of debt issuance costs. Cash used in operating activities also reflected a net change in operating assets and liabilities of $11.5 million, due principally to a decrease of $15.0 million in our deferred revenue balance from revenue recognized under our collaboration agreements, which was partially offset by an increase of $2.8 million in accrued compensation due to increased headcount and bonuses resulting from certain company goal achievements and a decrease of $0.7 million in accounts receivable from our collaborators.

Cash Flows from Investing Activities

Cash used in investing activities of $97.3million for the year ended December 31, 2021 was primarily related to purchases of marketable securities of $248.7million and purchases of property and equipment of $15.3million, principally for leasehold improvements to the premises under the Sublease, offset partially by maturities and sales of marketable securities of $166.7million.

Cash provided by investing activities of $0.6 million for the year ended December 31, 2020 was primarily related to purchases of marketable securities of $130.7 million and purchases of property and equipment of $7.1 million, principally for laboratory and manufacturing equipment, offset partially by maturities and sales of marketable securities of $138.4 million.

Cash Flows from Financing Activities

Cash provided by financing activities of $3.3million for the year ended December 31, 2021 was primarily related to $2.5million of proceeds received from the exercise of common stock options, and $1.8 million of net proceeds received from participants in our employee equity plans, partially offset by a $1.0 million tax payment related to the net share settlement of certain vested restricted stock units.

Cash provided by financing activities of $269.2 million for the year ended December 31, 2020 was primarily related to $251.4 million of net proceeds from the issuance of common stock from our public offering and the sales of common stock pursuant to our ATM Facility, $25.0 million of gross proceeds from our debt refinancing, and $2.8 million of net proceeds received from participants in our employee equity plans and from the exercise of common stock options, partially offset by a $10.0 million repayment of the August 2017 Loan (as defined in Note 7 to our financial statements included elsewhere in this report).

Contractual Obligations and Other Commitments

In addition to the contractual obligations and commitments as noted above and elsewhere in this Annual report with regards to the leases and term loans, we enter into agreements in the normal course of business, including with contract research organizations for clinical trials, contract manufacturing organizations for certain manufacturing services, and vendors for preclinical studies and other services and products for operating purposes, which are generally cancelable upon written notice.

Critical Accounting Policies and Estimates

Our management’s discussion and analysis of our financial condition and results of operations is based on our financial statements, which have been prepared in accordance with United States generally accepted accounting principles. The preparation of these financial statements requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements, as well as the reported revenue generated and expenses incurred during the reporting periods. Our estimates are based on our historical experience and on various other factors that we believe are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions or conditions.

While our significant accounting policies are described in the notes to our financial statements included elsewhere in this report, we believe that the following critical accounting policies are most important to understanding and evaluating our reported financial results.

Revenue Recognition

We do not have any products approved for commercial sale and have not generated any revenue from commercial product sales. Our total revenue to date has been generated principally from our collaboration and license agreements with Celgene (now BMS), Merck, and EMD Serono, and to a lesser extent, from manufacturing, supply and services and materials we provide to the above collaborators and to Vaxcyte.

When we enter into collaboration agreements, we assess whether the arrangements fall within the scope of ASC 808, Collaborative Arrangements (ASC 808) based on whether the arrangements involve joint operating activities and whether both parties have active participation in the arrangement and are exposed to significant risks and rewards. To the extent that the arrangement falls within the scope of ASC 808, we assess whether the payments between us and our collaboration partner fall within the scope of other accounting literature. If we conclude that payments from the collaboration partner to us represent consideration from a customer, such as license fees and contract research and development activities, we account for those payments within the scope of ASC 606, Revenue from Contracts with Customers. However, if we conclude that our collaboration partner is not a customer for certain activities and associated payments, such as for certain collaborative research, development, manufacturing and commercial activities, we present such payments as a reduction of research and development expense or general and administrative expense, based on where we present the underlying expense.

Collaboration revenue

provide options for the customer to acquire from us materials and reagents, clinical product supply or additional research and development services under separate agreements.

We assess which activities in the collaboration agreements are considered distinct performance obligations that should be accounted for separately. We develop assumptions that require judgement to determine whether the license to our intellectual property is distinct from the research and development services or participation in activities under the collaboration agreements.

Upfront Payments: For collaboration arrangements that include a nonrefundable upfront payment, if the license fee and research and development services cannot be accounted for as separate performance obligations, the transaction price is deferred and recognized as revenue over the expected period of performance using a cost-based input methodology. We use judgement to assess the pattern of delivery of the performance obligation. In addition, amounts paid in advance of services being rendered may result in an associated financing component to the upfront payment. Accordingly, the interest on such borrowing cost component will be recorded as interest expense and revenue, based on an appropriate borrowing rate applied to the value of services to be performed by us over the estimated service performance period.

License Grants: For collaboration arrangements that include a grant of a license to our intellectual property, we consider whether the license grant is distinct from the other performance obligations included in the arrangement. For licenses that are distinct, we recognize revenues from nonrefundable, upfront payments and other consideration allocated to the license when the license term has begun and we have provided all necessary information regarding the underlying intellectual property to the customer, which generally occurs at or near the inception of the arrangement.

Milestone and Contingent Payments: At the inception of the arrangement and at each reporting date thereafter, we assess whether we should include any milestone and contingent payments or other forms of variable consideration in the transaction price using the most likely amount method. If it is probable that a significant reversal of cumulative revenue would not occur upon resolution of the uncertainty, the associated milestone value is included in the transaction price. At the end of each subsequent reporting period, we re-evaluate the probability of achievement of each such milestone and any related constraint and, if necessary, adjust our estimate of the overall transaction price. Since milestone and contingent payments may become payable to us upon the initiation of a clinical study or filing for or receipt of regulatory approval, we review the relevant facts and circumstances to determine when we should update the transaction price, which may occur before the triggering event. When we update the transaction price for milestone and contingent payments, we allocate the changes in the total transaction price to each performance obligation in the agreement on the same basis as the initial allocation. Any such adjustments are recorded on a cumulative catch-up basis in the period of adjustment, which may result in recognizing revenue for previously satisfied performance obligations in such period. Our collaborators generally pay milestones and contingent payments subsequent to achievement of the triggering event.

Research and Development Services: For amounts allocated to our research and development obligations in a collaboration arrangement, we recognize revenue over time using a cost-based input methodology, representing the transfer of goods or services as activities are performed over the term of the agreement.

Materials Supply: We provide materials and reagents, clinical materials and services to certain of our collaborators under separate agreements. The consideration for such services is generally based on FTE personnel effort used to manufacture those materials reimbursed at an agreed upon rate in addition to agreed-upon pricing for the provided materials. The amounts billed are recognized as revenue as the performance obligations are met by us.

Research and Development

We record accrued expenses for estimated costs of our research and development activities conducted by third party service providers, which include outsourced research and development expenses, professional services and contract manufacturing activities. We record the estimated costs of research and development activities based upon the estimated amount of services provided but not yet invoiced, and include these costs in current liabilities in the balance sheets and within research and development expense in the statements of operations.

Nonrefundable advance payments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized and recognized as an expense as the goods are delivered or the related services are performed.

For outsourced research and development expenses, such as professional fees payable to third parties for preclinical studies, clinical trials and research services and other consulting costs, we estimate the expenses based on the services performed, pursuant to contracts with research institutions that conduct and manage preclinical studies, clinical trials and research services on our behalf. We estimate these expenses based on discussions with internal management personnel and external service providers as to the progress or stage of completion of services and the contracted fees to be paid for such services. If the actual timing of the performance of services or the level of effort varies from the original estimates, we will adjust the accrual accordingly. Payments made to third parties under these arrangements in advance of the performance of the related services by the third parties are recorded as prepaid expenses until the services are rendered.

Stock-Based Compensation

We recognize compensation costs related to stock-based awards granted to employees based on the estimated fair value of the awards on the date of grant. We account for forfeitures of stock-based awards as they occur. We estimate the grant date fair value, and the resulting stock-based compensation expense, using the Black-Scholes option-pricing model. The grant date fair value of the stock-based awards is generally recognized on a straight-line basis over the requisite service period, which is generally the vesting period of the respective awards.

The Black-Scholes option-pricing model requires the use of highly subjective assumptions to determine the fair value of stock-based awards, including the expected term and expected volatility of the underlying stock. We will continue to use judgment in evaluating the expected term and expected volatility utilized for our stock-based compensation calculations on a prospective basis.

The closing sale price per share of our common stock as reported on the Nasdaq Global Market on the date of grant is used to determine the exercise price per share of our stock-based awards to purchase common stock.

Income Taxes

As of December 31, 2021, we had federal net operating loss, or NOL, carryforwards of $281.7million and federal general business credits from research and development expenses totaling $25.1million, as well as state NOL carryforwards of $109.2million and state research and development credits of $17.2 million. If not utilized, the federal NOL carryforwards will expire at various dates beginning in 2032, and the federal credits will expire at various dates beginning in 2023. The state NOL carryforwards will expire at various dates beginning in 2030, if not utilized. The state research and development tax credits can be carried forward indefinitely.

Utilization of the net operating loss carryforwards may be subject to a substantial annual limitation due to the ownership change limitations provided by the Tax Reform Act of 1986, or the Tax Reform Act, as amended, and similar state provisions. The annual limitation may result in the expiration of NOLs and credits before utilization. We have performed a Section 382 study for the period of June 16, 2003 through December 31, 2020 and concluded that it is more likely than not that we experienced an ownership change on November 20, 2019. This change does not limit our ability to use our existing NOLs within the carryforward period provided by the Internal Revenue Code, subject to availability of taxable income. We may experience ownership changes in the future as a result of equity offerings or other shifts in our stock ownership, some of which are outside our control. If there is a subsequent event or further change in ownership, these losses may be subject to limitations, resulting in their expiration before they can be utilized.

We assess all material positions taken in any income tax return, including all significant uncertain positions, in all tax years that are still subject to assessment or challenge by relevant taxing authorities. Assessing an uncertain tax position begins with the initial determination of the position’s sustainability and is measured at the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. As of each balance sheet date, unresolved uncertain tax positions must be reassessed, and we will determine whether (i) the factors underlying the sustainability assertion have changed and (ii) the amount of the recognized tax benefit is still appropriate. The recognition and measurement of tax benefits requires significant judgment. Judgments concerning the recognition and measurement of a tax benefit might change as new information becomes available.

Recent Accounting Pronouncements

See Note 2 to our audited financial statements included elsewhere in this report for more information.

Item 7A. Quantitative and Qualitative Disclosures about Market Risk

We are exposed to market risks in the ordinary course of our business. These risks primarily include interest rate sensitivities. The primary objective of our investment activities is to preserve our capital to fund our operations. We also seek to maximize income from our investments without assuming significant risk. To achieve our objectives, we maintain a portfolio of cash equivalents and investments in a variety of securities of high credit quality.

We had cash, cash equivalents and marketable securities of $229.5million and $326.5 million as of December 31, 2021 and 2020, respectively, which consisted of money market funds, commercial paper, corporate debt securities, asset-backed securities, U.S. government agency securities and supranational debt securities. Such interest earning instruments carry a degree of interest rate risk; however, historical fluctuations in interest income have not been significant. Additionally, we had equity securities of $37.2 million as of December 31, 2021, consisting solely of common stock of Vaxcyte.

Equity risk is the risk we will incur economic losses due to adverse changes in equity prices. Our potential exposure to changes in equity prices results from our Vaxcyte common stock holdings. Therefore, we are subject to market risk if such holdings materially decrease in value. A hypothetical 10 percent decrease in the market price for our equity investments as of December 31, 2021 would decrease the fair value by $3.7 million. We intend to manage equity price risk going forward by continuously evaluating market conditions.

We do not enter into investments for trading or speculative purposes and have not used any derivative financial instruments to manage our interest rate risk exposure. We have not been exposed nor do we anticipate being exposed to material risks due to changes in interest rates. A hypothetical 10% change in market interest rates would not have a material impact on our financial statements. We do not believe that our cash, cash equivalents or marketable securities have significant risk of default or illiquidity.

As of December 31, 2021 and 2020, we had $25.1 million and $24.5 million, respectively, in debt outstanding, net of debt discount and accretion of final payment. Our debt with Oxford and SVB bears interest at a floating per annum rate equal to the greater of (i) 8.07% or (ii) the sum of (a) the greater of (1) the thirty (30) day U.S. LIBOR rate reported in the Wall Street Journal on the last business day of the month that immediately precedes the month in which the interest will accrue or (2) 1.67%, plus (b) 6.40%. This debt matures on March 1, 2024 and will be interest-only through March 1, 2022. Such interest-bearing debt carries a limited degree of interest rate risk. If overall interest rates had increased or decreased by 100 basis points during the periods presented our interest expense would not have been materially affected.

Item 8. Financial Statements and Supplementary Data

SUTRO BIOPHARMA, INC.

ANNUAL REPORT ON FORM 10-K

INDEX TO AUDITED FINANCIAL STATEMENTS

Page

Report of Independent Registered Public Accounting Firm (PCAOB ID 42) 123

Financial Statements

Balance Sheets 125

Statements of Operations 126

Statements of Comprehensive Loss 127

Statements of Stockholders’ Equity 128

Statements of Cash Flows 129

Notes to Financial Statements 130

Report of Independent Registered Public Accounting Firm

To the Stockholders and the Board of Directors of Sutro Biopharma, Inc.

Opinion on the Financial Statements

We have audited the accompanying balance sheets of Sutro Biopharma, Inc. (the Company) as of December 31, 2021 and 2020, the related statements of operations, comprehensive loss, stockholders’ equity and cash flows for each of the three years in the period ended December 31, 2021, and the related notes (collectively referred to as the “financial statements”). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company at December 31, 2021 and 2020, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2021, in conformity with U.S. generally accepted accounting principles.

We also have audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the Company's internal control over financial reporting as of December 31, 2021, based on criteria established in Internal Control-Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission (2013 framework) and our report dated February 28, 2022 expressed an unqualified opinion thereon.

Basis for Opinion

These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company’s financial statements based on our audits. We are a public accounting firm registered with the PCAOB and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matter

The critical audit matter communicated below is matter arising from the current period audit of the financial statements that was communicated or required to be communicated to the audit committee and that: (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective or complex judgments. The communication of the critical audit matter does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

Collaboration revenue

/s/ Ernst & Young LLP

We have served as the Company’s auditor since 2007.

Redwood City, California

February 28, 2022

SUTRO BIOPHARMA, INC.

BALANCE SHEETS

(in thousands, except share and per share data)

December 31,

Assets

Current assets:

Prepaid expenses and other current assets 8,123 4,486

Operating lease right-of-use assets 29,041 -

Marketable securities, non-current 68,775 -

Liabilities and Stockholders’ Equity

Current liabilities:

Operating lease liability—current 1,037 -

Deferred revenue, non-current - 6,100

Operating lease liability—non-current 31,224 -

Deferred rent - 1,340

Other non-current liabilities 146 481

Commitments and contingencies (Note 8)

Stockholders’ equity:

Accumulated other comprehensive (loss) income (314 ) 129

Total Liabilities and Stockholders’ Equity $ 341,408 $ 394,111

See accompanying notes to financial statements.

SUTRO BIOPHARMA, INC.

STATEMENTS OF OPERATIONS

(in thousands, except share and per share data)

Year Ended December 31,

Operating expenses

Unrealized (loss) gain on equity securities (4,454 ) 41,498 -

Net loss per share, basic and diluted $ (2.29 ) $ (0.99 ) $ (2.43 )

See accompanying notes to financial statements.

SUTRO BIOPHARMA, INC.

STATEMENTS OF COMPREHENSIVE LOSS

(in thousands)

Year Ended December 31,

Other comprehensive (loss) income:

Unrealized (loss) gain on available-for-sale securities (443 ) (36 ) 212

See accompanying notes to financial statements.

SUTRO BIOPHARMA, INC.

Statements of Stockholders’ Equity

(in thousands, except share amounts)

Accumulated

Additional Other Total

Common Stock Paid-In- Comprehensive Accumulated Stockholders’

Shares Amount Capital (Loss) Income Deficit Equity

Vesting of restricted stock units 114,103 - - - - -

Stock-based compensation expense - - 10,312 - - 10,312

Net unrealized gain on available-for-sale securities - - - 212 - 212

Vesting of restricted stock units 151,976 - - - - -

Stock-based compensation expense - - 11,917 - - 11,917

Net unrealized loss on available-for-sale securities - - (36 ) - (36 )

Return and retirement of common stock (7,687 ) - (7 ) (7 )

Vesting of restricted stock units 238,724 - - - - -

Stock-based compensation expense - - 23,241 - - 23,241

Net unrealized loss on available-for-sale securities - - (443 ) - (443 )

See accompanying notes to financial statements.

SUTRO BIOPHARMA, INC.

STATEMENTS OF CASH FLOWS

(in thousands)

Year Ended December 31,

Operating activities

Adjustments to reconcile net loss to net cash used in operating activities:

Noncash lease expenses 4,929 - -

Unrealized loss (gain) on equity securities 4,454 (41,498 ) -

Remeasurement of liability awards (12 ) 19 (115 )

Changes in operating assets and liabilities:

Prepaid expenses and other assets (3,959 ) (80 ) (1,441 )

Change in operating lease liability (2,727 ) - -

Investing activities

Purchases of equipment and leasehold improvements (15,323 ) (7,129 ) (3,481 )

Proceeds from exercise of options for Vaxcyte shares 9 89 -

Net cash (used in) provided by investing activities (97,315 ) 604 (51,131 )

Financing activities

Proceeds from sales of common stock, net of issuance costs - 251,415 (327 )

Proceeds from debt refinancing - 25,000 -

Proceed from exercise of common stock options 2,485 1,861 180

Return and retirement of common stock (7 ) - -

Net cash provided by (used in) financing activities 3,256 269,247 (4,184 )

Supplemental disclosure of cash flow information

Income tax paid $ 103 $ - $ -

Supplemental Disclosures of Non-cash Investing and Financing Information

Offering costs included in accounts payable $ - $ 361 $ -

Embedded interest associated with program fees $ 610 $ 1,852 $ 3,144

Warrants issued to lenders $ - $ 619 $ -

See accompanying notes to financial statements.

SUTRO BIOPHARMA, Inc.

Notes to Financial Statements

1.Organization and Principal Activities

Description of Business

Sutro Biopharma, Inc. (the “Company”) is a clinical stage drug discovery, development and manufacturing company focused on leveraging its integrated cell-free protein synthesis and site-specific conjugation platform, XpressCF®, to create a broad variety of optimally designed, next-generation protein therapeutics, initially for cancer. The Company was incorporated on April 21, 2003, and is headquartered in South San Francisco, California.

The Company operates in one business segment, the development of biopharmaceutical products.

Liquidity

The Company has incurred significant losses and has negative cash flows from operations. As of December 31, 2021, there was an accumulated deficit of $333.4 million. Management expects to continue to incur additional substantial losses in the foreseeable future as a result of the Company’s research and development and other operational activities.

As of December 31, 2021, the Company had unrestricted cash, cash equivalents and marketable securities of $229.5million, which is available to fund future operations. The Company will need to raise additional capital to support the completion of its research and development activities and to support its operations.

The Company believes that its unrestricted cash, cash equivalents and marketable securities as of December 31, 2021 will enable the Company to maintain its operations for a period of at least 12 months following the filing date of these financial statements.

2. Basis of Presentation and Summary of Significant Accounting Policies

Basis of Presentation and Use of Estimates

The accompanying financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”). The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. The Company bases its estimates on historical experience and market-specific or other relevant assumptions that it believes are reasonable under the circumstances. The amounts of assets and liabilities reported in the Company’s balance sheets and the amounts of expenses and income reported for each of the periods presented are affected by estimates and assumptions, which are used for, but are not limited to, determining research and development periods under collaboration arrangements, stock-based compensation expense, valuation of marketable securities, impairment of long-lived assets, income taxes and certain accrued liabilities. Actual results could differ from such estimates or assumptions.

The full extent to which the COVID-19 pandemic will directly or indirectly impact the Company’s business, results of operations and financial condition, including revenue, expenses, manufacturing, clinical trials, research and development costs and employee-related amounts, will depend on future developments that are highly uncertain, including as a result of new information that may emerge concerning COVID-19 and the actions taken to contain or treat it, as well as the economic impact on local, regional, national and international customers, suppliers, service providers and markets. The Company has made estimates of the impact of COVID-19 within its financial statements and there may be changes to those estimates in future periods. Actual results could differ from such estimates or assumptions.

Recently Adopted Accounting Pronouncements

In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Updates (“ASU”) 2016-13 (Topic 326), Financial Instruments Credit Losses. The guidance modifies the measurement and recognition of credit losses for most financial assets and certain other instruments. The amendment updates the guidance for measuring and recording credit losses on financial assets measured at amortized cost by replacing the “incurred loss” model with an “expected loss” model. The Company adopted ASU 2016-13 in the third quarter of 2021 using the modified retrospective adoption approach. As a result of this adoption, the Company presents these financial assets, which include accounts receivable and available-for-sale debt securities, at the net amount the Company expects to collect. The amendment also requires the Company to record credit losses related to available-for-sale debt securities as an allowance through net income rather than reducing the carrying amount under the historical, other-than-temporary-impairment model. The adoption of ASU 2016-13 did not have a material impact on the Company’s financial statements and related disclosures for the year ended December 31, 2021.

In February 2016, the FASB issued ASU 2016-02 (Topic 842), Leases (Accounting Standards Codification, or “ASC”, 842). ASC 842 supersedes the lease recognition requirements in ASC 840, Leases. ASC 842 clarifies the definition of a lease and requires lessees to recognize right-of-use assets and lease liabilities for all leases, including those classified as operating leases under previous lease accounting guidance. The Company adopted ASC 842 on July 1, 2021, effective as of January 1, 2021. There was no impact on the Company’s accumulated deficit as of January 1, 2021 as a result of the adoption of this standard. Results for the period ended December 31, 2021 are presented under Topic 842. Other prior period amounts are not adjusted and continue to be reported in accordance with the Company's historic accounting under previous lease guidance, ASC Topic 840: Leases (“Topic 840”). The Company elected the package of practical expedients permitted under the transition guidance of the new standard, which allowed the Company to carry forward its historical assessment on whether a contract is or contains a lease, lease classification, and initial direct costs. Upon adoption on January 1, 2021, the Company recognized operating lease right-of-use (“ROU”) assets of $29.7 million, and current and non-current operating lease liabilities of $2.9 million and $27.8 million, respectively. In connection with the adoption of this standard, deferred rent of $1.3 million and prepaid rent of $0.3 million, which was previously recorded in prepaid expenses and other current assets on the balance sheet as of December 31, 2020, were derecognized. Finance lease assets and liabilities were not material. The adoption of ASC 842 did not have a material impact on the Company’s Statements of Operations and Statements of Cash flows.

Recent Accounting Pronouncements Not Yet Adopted

In March 2020, the FASB issued ASU 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting”, which provides optional expedients and exceptions for a limited period of time to ease the potential burden in accounting treatments related to contracts, hedging relationships and other transactions affected by reference rate reform if certain criteria are met. Adoption of the expedients and exceptions is elective and is permitted upon issuance of the guidance through December 31, 2022. The Company does not expect that the new guidance will have material impact on its financial position, results of operations and cash flows.

Cash, Cash Equivalents, Marketable Securities and Restricted Cash

The Company considers all highly liquid investments with original maturities of 90 days or less from the date of purchase to be cash equivalents. Investments with original maturities of greater than 90 days from the date of purchase but less than one year from the balance sheet date, or where the Company's intent is to use the investments to fund current operations or to make them available for current operations are classified as current, while investments with maturities in one year or beyond one year from the balance sheet date are classified as long-term investments.

Available-for-sale marketable securities are carried at fair value, with unrealized gains and losses reported as a component of accumulated other comprehensive income (loss). Realized gains and losses are included in interest income in the Company’s Statements of Operations. There were no material realized gains or losses in the periods presented. The cost of securities sold is based on the specific-identification method.

The Company evaluates, on a quarterly basis, its marketable securities for potential impairment. For marketable securities in an unrealized loss position, the Company assesses whether such declines are due to credit loss based on factors such as changes to the rating of the security by a ratings agency, market conditions and supportable forecasts of economic and market conditions, among others. If a credit loss exists, the Company assesses whether it has plans to sell the security or it is more likely than not it will be required to sell any marketable security before recovery of its amortized cost basis. If either condition is met, the security’s amortized cost basis is written down to fair value and is recognized through interest and other expense, net.

If neither condition is met, declines as a result of credit losses, if any, are recognized as an allowance for credit loss, limited to the amount of unrealized loss, through interest and other expense, net. Any portion of unrealized loss that is not a result of a credit loss, is recognized in other comprehensive income (loss).

The Company invests in money market funds, commercial paper, corporate debt securities, asset-based securities and U.S. government agency securities with high credit ratings. The Company has established guidelines regarding diversification of its investments and their maturities, with the objectives of maintaining safety and liquidity while maximizing yield.

Under certain agreements, the Company has pledged cash and cash equivalents as collateral. Restricted cash related to such agreements was $0.9 million and $0.9 million, respectively, as of December 31, 2021 and 2020.

A reconciliation of cash, cash equivalents, and restricted cash reported within the Company’s Balance Sheets to the amount reported within the accompanying Statements of Cash Flows was as follows:

December 31,

(in thousands)

Concentrations of Credit Risk

Cash and cash equivalents and marketable securities consist of financial instruments that potentially subject the Company to a concentration of credit risk, to the extent of the amounts recorded on the balance sheets. The Company minimizes the amount of credit exposure by investing cash that is not required for immediate operating needs in money market funds, government obligations and/or commercial paper with short maturities.

The Company performs a regular review of its collaborators’ credit risk and payment histories when circumstances warrant, including payments made subsequent to year-end. When appropriate, the Company provides for an allowance for credit risks by reserving for specifically identified doubtful accounts, although historically the Company has not experienced credit losses from its accounts receivable.

Investments in Equity Securities

Subsequent to the closing of the initial public offering (“IPO”) of Vaxcyte, Inc. in June 2020, the fair value of Vaxcyte’s common stock became readily determinable. As a result, beginning June 2020, Vaxcyte common stock held by the Company is measured at fair value at each reporting period based on the closing price of Vaxcyte’s common stock on the last trading day of each reporting period, with any unrealized gains and losses recorded in the Company’s statements of operations.

Property and Equipment, Net

Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is determined using the straight-line method over the estimated useful lives of the respective assets, generally three to five years. Leasehold improvements are amortized on a straight-line basis over the shorter of their estimated useful lives or the term of the lease. Maintenance and repairs are charged to expense as incurred and costs of improvement are capitalized.

Impairment of Long-Lived Assets

The Company reviews long-lived assets, including property and equipment, leasehold improvements and right-of-use assets for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. An impairment loss would be recognized when the estimated, undiscounted future cash flows expected to result from the use of the asset and its eventual disposition are less than its carrying amount. Impairment, if any, is measured as the amount by which the carrying amount of a long-lived asset exceeds its fair value.

The Company did not recognize any impairment charges during the years ended December 31, 2021, 2020 and 2019. As of December 31, 2021 and 2020, management believes that no revision to the remaining useful lives or write down of the remaining long-lived assets is required.

Leases

The Company determines if an arrangement is or contains a lease at contract inception by assessing whether the arrangement contains an identified asset and whether the lessee has the right to control such asset. The Company is required to classify leases as either finance or operating leases and to record a ROU asset and a lease liability for all leases with a term greater than 12 months regardless of the lease classification. The lease classification will determine whether the lease expense is recognized based on an effective interest rate method or on a straight-line basis over the term of the lease. The Company determines the initial classification and measurement of its ROU assets and lease liabilities at the lease commencement date and thereafter, if modified. The Company does not have material finance leases.

For leases with a term greater than 12 months, the Company records the related ROU asset and lease liability at the present value of lease payments over the term of the lease. The term of the Company’s leases equals the non-cancellable period of the lease, including any rent-free periods provided by the lessor, and also includes options to extend or terminate the lease that the Company is reasonably certain to exercise. The ROU asset equals the carrying amount of the related lease liability, adjusted for any lease payments made prior to lease commencement and lease incentives provided by the lessor. Variable lease payments are expensed as incurred and do not factor into the measurement of the applicable ROU asset or lease liability.

The Company has elected, for all classes of underlying assets, not to recognize ROU assets and lease liabilities for leases with a term of 12 months or less. Lease cost for short-term leases is recognized on a straight-line basis over the lease term. The Company has also elected to not separate lease and non-lease components for its leases and, as a result, accounts for lease and non-lease components as one component.

The Company’s leases do not provide a readily determinable implicit rate. Therefore, the Company estimates its incremental borrowing rate to discount the lease payments based on information available at lease commencement. The Company determines its incremental borrowing rate based on the rate of interest that the Company would have to pay to borrow, on a collateralized basis over a similar term, an amount equal to the lease payments in a similar economic environment.

Lease payments may be fixed or variable; however, only fixed payments are included in the Company’s lease liability calculation. Lease costs for the Company’s operating leases are recognized on a straight-line basis within operating expenses over the lease term. The Company’s lease agreements may contain variable non-lease components such as common area maintenance, operating expenses or other costs, which are expensed as incurred.

Revenue Recognition

On January 1, 2019, the Company adopted Accounting Standards Update (ASU) No. 2014-09 (Topic 606), Revenue from Contracts with Customers (“ASC 606”). Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of ASC 606, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation.

When the Company enters into collaboration agreements, it assesses whether the arrangements fall within the scope of ASC 808, Collaborative Arrangements (ASC 808) based on whether the arrangements involve joint operating activities and whether both parties have active participation in the arrangement and are exposed to significant risks and rewards. To the extent that the arrangement falls within the scope of ASC 808, the Company assesses whether the payments between the Company and its collaboration partner fall within the scope of other accounting literature. If it concludes that payments from the collaboration partner to the Company represent consideration from a customer, such as license fees and contract research and development activities, the Company accounts for those payments within the scope of ASC 606, Revenue from Contracts with Customers. However, if the Company concludes that its collaboration partner is not a customer for certain activities and associated payments, such as for certain collaborative research, development, manufacturing and commercial activities, the Company presents such payments as a reduction of research and development expense or general and administrative expense, based on where the Company presents the underlying expense.

The Company has no products approved for commercial sale and has not generated any revenue from commercial product sales. The total revenue to date has been generated principally from collaboration and license agreements and to a lesser extent, from manufacturing, supply and services and materials the Company provides to its collaboration partners.

Collaboration Revenue

The Company derives revenue from collaboration arrangements, under which the Company may grant licenses to its collaboration partners to further develop and commercialize its proprietary product candidates. The Company may also perform research and development activities under the collaboration agreements. Consideration under these contracts generally includes a nonrefundable upfront payment, development, regulatory and commercial milestones and other contingent payments, and royalties based on net sales of approved products. Additionally, the collaborations may provide options for the customer to acquire from the Company materials and reagents, clinical product supply or additional research and development services under separate agreements.

The Company assesses which activities in the collaboration agreements are considered distinct performance obligations that should be accounted for separately. The Company develops assumptions that require judgement to determine whether the license to the Company’s intellectual property is distinct from the research and development services or participation in activities under the collaboration agreements.

At the inception of each agreement, the Company determines the arrangement transaction price, which includes variable consideration, based on the assessment of the probability of achievement of future milestones and contingent payments and other potential consideration. The Company recognizes revenue over time by measuring its progress towards the complete satisfaction of the relevant performance obligation using an appropriate input or output method based on the nature of the service promised to the customer.

For arrangements that include multiple performance obligations, the Company allocates the transaction price to the identified performance obligations based on the standalone selling price, or SSP, of each distinct performance obligation. In instances where SSP is not directly observable, the Company develops assumptions that require judgment to determine the SSP for each performance obligation identified in the contract. These key assumptions may include FTE, personnel effort, estimated costs, discount rates and probabilities of clinical development and regulatory success.

Upfront Payments: For collaboration arrangements that include a nonrefundable upfront payment, if the license fee and research and development services cannot be accounted for as separate performance obligations, the transaction price is deferred and recognized as revenue over the expected period of performance using a cost-based input methodology. The Company uses judgement to assess the pattern of delivery of the performance obligation. In addition, amounts paid in advance of services being rendered may result in an associated financing component to the upfront payment. Accordingly, the interest on such borrowing cost component will be recorded as interest expense and revenue, based on an appropriate borrowing rate applied to the value of services to be performed by the Company over the estimated service performance period.

License Grants: For collaboration arrangements that include a grant of a license to the Company’s intellectual property, the Company considers whether the license grant is distinct from the other performance obligations included in the arrangement. For licenses that are distinct, the Company recognizes revenues from nonrefundable, upfront payments and other consideration allocated to the license when the license term has begun and the Company has provided all necessary information regarding the underlying intellectual property to the customer, which generally occurs at or near the inception of the arrangement.

Milestone and Contingent Payments: At the inception of the arrangement and at each reporting date thereafter, the Company assesses whether it should include any milestone and contingent payments or other forms of variable consideration in the transaction price using the most likely amount method. If it is probable that a significant reversal of cumulative revenue would not occur upon resolution of the uncertainty, the associated milestone value is included in the transaction price. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of each such milestone and any related constraint and, if necessary, adjusts its estimate of the overall transaction price. Since milestone and contingent payments may become payable to the Company upon the initiation of a clinical study or filing for or receipt of regulatory approval, the Company reviews the relevant facts and circumstances to determine when the Company should update the transaction price, which may occur before the triggering event. When the Company updates the transaction price for milestone and contingent payments, the Company allocates the changes in the total transaction price to each performance obligation in the agreement on the same basis as the initial allocation. Any such adjustments are recorded on a cumulative catch-up basis in the period of adjustment, which may result in recognizing revenue for previously satisfied performance obligations in such period. The Company’s collaborators generally pay milestones and contingent payments subsequent to achievement of the triggering event.

Research and Development Services: For amounts allocated to the Company’s research and development obligations in a collaboration arrangement, the Company recognizes revenue over time using a cost-based input methodology, representing the transfer of goods or services as activities are performed over the term of the agreement.

Materials Supply: The Company provides materials and reagents, clinical materials and services to certain of its collaborators under separate agreements. The consideration for such services is generally based on FTE personnel effort used to manufacture those materials reimbursed at an agreed upon rate in addition to agreed-upon pricing for the provided materials. The amounts billed are recognized as revenue as the performance obligations are met by the Company.

Stock-Based Compensation

The Company maintains a stock-based compensation plan as a long-term incentive for employees, consultants, and members of the Company’s Board of Directors. The plan allows for the issuance of restricted stock units, non-statutory and incentive stock options to employees and non-statutory stock options (“NSOs”) to nonemployees. The Company also maintains an employee stock purchase plan.

Share-based payments, including purchases under the Company’s employee stock purchase plan, are measured using fair-value-based measurements and recognized as compensation expense over the service period in which the awards are expected to vest. The Company’s fair-value-based measurements of awards to employees and directors as of the grant date utilize the single-option award-valuation approach, and the Company uses the straight-line method for expense attribution. The fair-value-based measurements of options granted to nonemployees are remeasured at each period end until the options vest and are amortized to expense as earned. The Company accounts for forfeitures of stock-based awards as they occur. The valuation model used for calculating the estimated fair value of stock awards is the Black-Scholes option-pricing model. The Black-Scholes model requires the Company to make assumptions and judgments about the variables used in the calculations, including the expected term (weighted-average period of time that the options granted are expected to be outstanding), the expected volatility of the Company’s common stock, the related risk-free interest rate and the expected dividends.

Research and Development

The Company records accrued expenses for estimated costs of the research and development activities conducted by third party service providers, which include outsourced research and development expenses, professional services and contract manufacturing activities. The Company records the estimated costs of research and development activities based upon the estimated amount of services provided but not yet invoiced, and includes these costs in current liabilities in the balance sheets and within research and development expense in the statements of operations.

For outsourced research and development expenses, such as professional fees payable to third parties for preclinical studies, clinical trials and research services and other consulting costs, the Company estimates the expenses based on the services performed, pursuant to contracts with research institutions that conduct and manage preclinical studies, clinical trials and research services on the Company’s behalf. The Company estimates these expenses based on discussions with internal management personnel and external service providers as to the progress or stage of completion of services and the contracted fees to be paid for such services. If the actual timing of the performance of services or the level of effort varies from the original estimates, the Company will adjust the accrual accordingly. Payments made to third parties under these arrangements in advance of the performance of the related services by the third parties are recorded as prepaid expenses until the services are rendered.

Income Taxes

The Company provides for income taxes under the asset and liability method. Current income tax expense or benefit represents the amount of income taxes expected to be payable or refundable for the current year. Deferred income tax assets and liabilities are determined based on differences between the financial statement reporting and tax bases of assets and liabilities and net operating loss and credit carryforwards, and are measured using the enacted tax rates and laws that will be in effect when such items are expected to reverse. Deferred income tax assets are reduced, as necessary, by a valuation allowance when management determines it is more likely than not that some or all of the tax benefits will not be realized.

The Company accounts for uncertain tax positions in accordance with Accounting Standards Codification (“ASC”) 740-10, Accounting for Uncertainty in Income Taxes. The Company assesses all material positions taken in any income tax return, including all significant uncertain positions, in all tax years that are still subject to assessment or challenge by relevant taxing authorities. Assessing an uncertain tax position begins with the initial determination of the position’s sustainability and is measured at the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. As of each balance sheet date, unresolved uncertain tax positions must be reassessed, and the Company will determine whether (i) the factors underlying the sustainability assertion have changed and (ii) the amount of the recognized tax benefit is still appropriate. The recognition and measurement of tax benefits requires significant judgment. Judgments concerning the recognition and measurement of a tax benefit might change as new information becomes available.

The Company includes any penalties and interest expense related to income taxes as a component of Interest and other income (expense), net, as necessary.

Fair Value Measurements

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability, or an exit price, in the principal or most advantageous market for that asset or liability in an orderly transaction between market participants on the measurement date, and establishes a fair value hierarchy that requires an entity to maximize the use of observable inputs, where available, and minimize the use of unobservable inputs when measuring fair value. The Company determined the fair value of financial assets and liabilities using the fair value hierarchy that describes three levels of inputs that may be used to measure fair value, as follows:

Level 1—Quoted prices in active markets for identical assets and liabilities;

Level 2—Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities; and

Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

The carrying amounts of accounts receivable, prepaid expenses, accounts payable, accrued liabilities and accrued compensation and benefits approximate fair value due to the short-term nature of these items.

The fair value of the Company’s outstanding loan(See Note 7) is estimated using the net present value of the payments, discounted at an interest rate that is consistent with market interest rate, which is a Level 2 input. The estimated fair value of the Company’s outstanding loan approximates the carrying amount, as the loan bears a floating rate that approximates the market interest rate.

Net Loss Per Share

Basic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of common stock outstanding for the period, without consideration for potential dilutive common shares. Basic net loss per share is the same as diluted net loss per share as the inclusion of all potentially dilutive securities would have been anti-dilutive given the net loss of the Company.

3. Fair Value Measurements

The following table sets forth the fair value of the Company’s financial assets and liabilities measured on a recurring basis by level within the fair value hierarchy:

Total Level 1 Level 2 Level 3

(in thousands)

Assets:

Total Level 1 Level 2 Level 3

(in thousands)

Assets:

Where applicable, the Company uses quoted market prices in active markets for identical assets to determine fair value. This pricing methodology applies to Level 1 investments, which are comprised of money market funds, U.S. government securities and the shares of Vaxcyte common stock held by the Company.

If quoted prices in active markets for identical assets are not available, then the Company uses quoted prices for similar assets or inputs other than quoted prices that are observable, either directly or indirectly. These investments are included in Level 2 and consist of commercial paper, corporate debt securities, asset-backed securities and supranational debt securities. These assets are valued using market prices when available, adjusting for accretion of the purchase price to face value at maturity.

A financial instrument’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability.

In certain cases where there is limited activity or less transparency around inputs to valuation, securities are classified as Level 3 within the valuation hierarchy. As of December 31, 2021 and 2020, the Company did not hold any securities that were classified as Level 3 within the valuation hierarchy.

Investments in Equity Securities

Subsequent to the closing of the initial public offering (“IPO”) of Vaxcyte in June 2020, the fair value of Vaxcyte’s common stock became readily determinable. As a result, beginning June 2020, Vaxcyte common stock held by the Company is measured at fair value at each reporting period based on the closing price of Vaxcyte’s common stock on the last trading day of each reporting period, with any unrealized gains and losses recorded in the Company’s statements of operations.

As of December 31, 2021 and 2020, the Company held 1,562,879 and 1,567,324 shares, respectively, of Vaxcyte common stock with an estimated fair value of $37.2 million and $41.6 million, respectively. The Company recognized an unrealized (loss) gain of ($4.5) million and $41.5 million for the year ended December 31, 2021 and 2020, respectively, whichresulted from the change in estimated fair value of Vaxcyte common stock, adjusted by a $9,000 and $146,000 payment received for call option exercises and a revaluation of a prior preferred stock warrant converted to common stock for the year ended December 31, 2021 and 2020, respectively.

4. Cash Equivalents and Marketable Securities

Cash equivalents and marketable securities consisted of the following:

AmortizedCost Basis UnrealizedGains UnrealizedLosses FairValue

(in thousands)

Less amounts classified as cash equivalents (29,451 ) - - (29,451 )

AmortizedCost Basis UnrealizedGains UnrealizedLosses FairValue

(in thousands)

Less amounts classified as cash equivalents (204,632 ) - - (204,632 )

As of December 31, 2021 and 2020, $68.8 million and zero, respectively, of marketable securities had maturities of more than one year and are classified as long-term assets.

There were $176.5 million and $14.7 million of investments in an unrealized loss position of $0.3 million and $3,000 as of December 31, 2021 and 2020, respectively. During the years ended December 31, 2021, 2020 and 2019, the Company did not record any other-than-temporary impairment charges on its available-for-sale securities. Based on the Company’s procedures under the expected credit loss model, including an assessment of unrealized gains on the portfolio after December 31, 2021, the Company concluded that the unrealized losses for its marketable securities were not attributable to credit and therefore an allowance for credit losses for these securities has not been recorded as of December 31, 2021. Also, based on the scheduled maturities of the investments, the Company was more likely than not to hold these investments for a period of time sufficient for a recovery of the Company’s cost basis.

The Company recognized no material gains or losses on its cash equivalents and current and non-current marketable securities as of December 31, 2021 and as a result, the Company did not reclassify any amounts out of accumulated other comprehensive income for the year then ended.

5. Collaboration and License Agreements and Supply Agreements

The Company has entered into collaboration and license agreements and supply agreements with various pharmaceutical and biotechnology companies. The Company analyzes its agreements to determine whether it should account for the agreements within the scope of ASC 808, and, if so, it analyzes whether it should account for any elements under ASC 606.

The Company’s accounts receivable balances may contain billed and unbilled amounts from upfront payments, milestones and other contingent payments, as well as reimbursable costs from collaboration and license agreements and supply agreements. The Company has not experienced credit loss from its accounts receivable and, therefore, has not recorded a reserve for estimated credit losses as of December 31, 2021.

In accordance with its agreements, the Company recognized revenue as follows:

Year Ended December 31,

(in thousands)

(1)

In January 2019, BMS announced the entry into a definitive agreement to acquire Celgene and the transaction was completed in November 2019.

(2)

Merck was a related party until the closing of the Company's public offering on May 14, 2020.

(3)

Vaxcyte was a related party until the closing of its initial public offering on June 16, 2020.

The following table presents the changes in the Company’s deferred revenue balance from its agreements during the year ended December 31, 2021:

Year ended

(in thousands)

Additions to deferred revenue 23,402

Recognition of revenue in current period (38,609 )

The Company’s balance of deferred revenue contains a license option payment and the transaction price from collaboration agreements allocated to performance obligations which are partially unsatisfied. The Company expects to recognize approximately $5.5 million of the deferred revenue over the next twelve months.

There have been no material changes to the Company’s agreements during the year ended December 31, 2021, except as described below.

Collaboration with BMS

BMS Agreement

In November 2019, BMS acquired Celgene, and Celgene became a wholly owned subsidiary of BMS. In connection with such acquisition, BMS assumed the rights and obligations of the 2014 Celgene Agreement, 2017 Celgene Agreement and 2018 Celgene Master Services Agreement. Throughout this Annual Report, the Company refers to Celgene as BMS and the Company's agreements with Celgene as the BMS Agreement and the 2018 BMS Master Services Agreement.

In September 2014, the Company signed a Collaboration and License Agreement (the “BMS Agreement”) with BMS to discover and develop bispecific antibodies and/or antibody-drug conjugates (“ADCs”), focused primarily on the field of immuno-oncology, using the Company’s proprietary integrated cell-free protein synthesis platform, XpressCF®. In August 2017, the Company entered into an amended and restated collaboration and license agreement with BMS to refocus the collaboration on four programs that were advancing through preclinical development, including an ADC program targeting B cell maturation antigen (“BCMA ADC”).

In May 2019, the U.S. Food and Drug Administration cleared the investigational new drug (“IND”) application for the BCMA ADC, which was discovered and is being manufactured by the Company and is the first collaboration program IND. BMS has worldwide development and commercialization rights with respect to the BCMA ADC. The Company will continue to be responsible for clinical supply manufacturing and certain development services for the BCMA ADC and is eligible to receive from BMS aggregate development and regulatory contingent payments of up to $275.0 million, if approved in multiple indications, and tiered royalties ranging from mid to high single digit percentages on worldwide sales of any resulting commercial products.

As of December 31, 2021 and 2020, there was no balance of deferred revenue related to payments received by the Company under the BMS Agreement.

2018 BMS Master Services Agreement

In March 2018, the Company entered into a Master Development and Clinical Manufacturing Services Agreement (the “2018 BMS Master Services Agreement”) with BMS, wherein BMS requested the Company to provide development, manufacturing and supply chain management services, including clinical product supply.

As of December 31, 2021 and 2020, there was $0.6 million and $1.2 million, respectively, of deferred revenue under the 2018 BMS Master Services Agreement.

Revenues under the BMS Agreement and the 2018 BMS Master Services Agreement were as follows:

Year ended December 31,

(in thousands)

Collaboration with Merck

2018 Merck Agreement

In July 2018, the Company entered into an agreement (the “2018 Merck Agreement”) with Merck for access to the Company’s technology and the identification and preclinical research and development of two target programs, with an option for Merck to engage the Company to continue these activities for a third program, upon the payment of an additional amount, focusing on cytokine derivatives for cancer and autoimmune disorders with an initial transaction price of $60.0 million. The option to expand activities to a third program expired in January 2021.

Under ASC 606, the Company determined there was a financing component associated with the $60.0 million upfront payment and has calculated total interest expense of $7.3 million as of December 31, 2021, on the unearned revenue portion beyond one year from the effective date of the agreement, which amount was recognized as interest expense and revenue over the service period for the first and second target programs.

In March 2020, Merck exercised its option to extend the research term of the collaboration’s first cytokine-derivative program by one year, which, pursuant to the terms of the 2018 Merck Agreement, triggered a payment of $5.0 million. The $5.0 million was, in prior periods, considered to be a fully constrained variable consideration. Removal of the constraint on this variable consideration resulted in a change to the total transaction price, from

$60.0 million to $65.0 million. The Company allocated the updated transaction price to all identified performance obligations on the same basis as the initial allocation upon inception of the 2018 Merck Agreement, with any adjustments recorded as a cumulative catch-up in the current period.

In the second quarter of 2021, the Company earned a $15.0 million contingent payment for the initiation by Merck of the first IND-enabling toxicology study under the first cytokine-derivative program in the collaboration. The $15.0 million was, in prior periods, considered to be a fully constrained variable consideration. Removal of the constraint on this variable consideration resulted in a change to the total transaction price, from $65.0 million to $80.0 million. The Company allocated the updated transaction price to all identified performance obligations on the same basis as the initial allocation upon inception of the 2018 Merck Agreement, with any adjustments recorded as a cumulative catch-up in the period ended December 31, 2021. As a result of the change in transaction price, the Company recognized substantially all of the $15.0 million contingent payment, with a remaining $0.3 million related to the Joint Steering Committee, ("JSC") performance obligation, as a cumulative catch-up in revenue in the period ended December 31, 2021.

In September 2021, the Company entered into an amendment to the 2018 Merck Agreement (the “2021 Amendment”) to extend the research term for the first program in the 2018 Merck Agreement to discover and develop novel cytokine derivative therapeutics for cancer and autoimmune disorders. Under the terms of the 2021 Amendment, the Company received a payment of $2.5 million and may receive up to an additional $7.5 million upon the achievement of certain developmental milestones. Pursuant to ASC 606, the Company concluded that the 2021 Amendment constitutes a contract modification which is to be accounted for as a separate contract from the 2018 Merck Agreement. From the $2.5 million payment received, $1.9 million was recognized as revenue on a proportion of performance basis in the year ended December 31, 2021, related to the Company’s identified performance obligations under the 2021 Amendment. The additional $7.5 million is considered to be fully constrained variable consideration.

In December 2021, Merck did not extend the research term for the second research program of the collaboration and that research program reverted to the Company. The first program of the collaboration is focused on two distinct cytokine derivative molecules for the treatment of cancer. The Company is also eligible to receive aggregate contingent payments of up to approximately $0.5 billion for the target program selected by Merck, assuming the development and sale of the therapeutic candidate and all possible indications identified under the collaboration. If one or more products from the target program isdeveloped for non-oncology or a single indication, the Company will be eligible for reduced aggregate milestone payments. In addition, the Company is eligible to receive tiered royalties ranging from mid-single digit to low teen percentages on the worldwide sales of any commercial products that may result from the collaboration.

As of December 31, 2021 and 2020, there was a total of $0.9 million and $18.5 million, respectively, of deferred revenue related to the 2018 Merck Agreement and 2021 Amendment.

2020 Merck Master Services Agreement

In August 2020, the Company entered into a Pre-Clinical and Clinical Supply Agreement (the “2020 Merck Master Services Agreement”) with Merck, wherein Merck requested the Company to provide development, manufacturing and supply chain management services, including clinical product supply, upon completion of the research programs under the 2018 Merck Agreement.

As of both December 31, 2021 and 2020, there was no deferred revenue under the 2020 Merck Master Services Agreement.

Revenues under the 2018 Merck Agreement and the 2020 Merck Master Services Agreement were as follows:

Year ended December 31,

(in thousands)

Collaboration with EMD Serono

EMD Serono Agreements

The Company signed a Collaboration Agreement and a License Agreement with EMD Serono in May 2014 and September 2014, respectively, which were entered into in contemplation of each other and therefore treated as a single agreement for accounting purposes. The Collaboration Agreement was subsumed into the License Agreement (the “MDA Agreement”), which agreement is to develop ADCs for multiple cancer targets. Under the MDA Agreement, a novel bispecific ADC product candidate targeting EGFR and MUC1, known as M1231, is undergoing development.

The Company is eligible to receive up to $52.5 million for M1231 under the MDA Agreement, primarily from pre-commercial contingent payments. Relatedly, the Company earned a $2.0 million contingent payment in the second quarter of 2021 related to a patient enrollment achievement in the Phase 1 dose escalation portion of a study of M1231. In August 2020, the Company earned a $1.0 million clinical supply milestone payment under the MDA Agreement. In September 2019, the Company earned a $1.5 million contingent payment under the MDA Agreement upon designation by EMD Serono of a specific bispecific antibody drug conjugate as a clinical development candidate with their approval to advance it to IND-enabling studies. In addition, the Company is eligible to receive tiered royalties ranging from low-to-mid single digit percentages, along with certain additional one-time royalties, on worldwide sales of any commercial products that may result from the MDA Agreement.

As of both December 31, 2021 and 2020, there was no deferred revenue related to payments received by the Company under the MDA Agreement.

2019 EMD Serono Supply Agreement

In April 2019, the Company entered into an ADC Product Preclinical and Phase I Clinical Supply Agreement (the “2019 EMD Serono Supply Agreement”) with EMD Serono, wherein EMD Serono requested the Company to provide development, manufacturing and supply chain management services, including clinical product supply.

As of December 31, 2021 and 2020, there was zeroand $1 million, respectively, of deferred revenue related to payments received by the Company under the 2019 EMD Serono Supply Agreement.

Revenues under the EMD Serono agreements were as follows:

Year ended December 31,

(in thousands)

Vaxcyte Supply Agreement

In May 2018, the Company entered into a Supply Agreement (the “Supply Agreement”) with Vaxcyte, wherein Vaxcyte engaged the Company to provide research and development services and to supply extracts and custom reagents, as requested by Vaxcyte. The pricing is based on an agreed upon cost plus arrangement.

During 2020, upon Vaxcyte’s request and their agreement to reimburse the related costs, the Company entered into agreements with third-party contract manufacturers (“CMOs”) to conduct process transfers to allow for such CMOs to manufacture and supply extract and custom reagents for Vaxcyte. For the year ended December 31, 2021 and 2020, the agreed-upon reimbursements by Vaxcyte of the costs associated with such arrangements, principally for pass-through costs from the CMOs, were $8.9 million and $0.5 million, respectively, and were accounted for by the Company as a reduction to research and development expense based on the Company’s conclusion that Vaxcyte was not a customer for such activities and associated payments.

Revenues under the Vaxcyte Supply Agreementwere as follows:

Year ended December 31,

(in thousands)

Research and development services $ 1,131 $ 184 $ –

BioNova Option Agreement

In October 2021, the Company entered into an agreement with BioNova to confer BioNova the option to obtain exclusive rights to develop and commercialize STRO-001 in China, Hong Kong, Macau and Taiwan, referred to as Greater China. BioNova will pursue the clinical development, regulatory approval, and commercialization of STRO-001 in multiple indications, including non-Hodgkin's lymphoma, multiple myeloma, and leukemia in the licensed territory. The Company will retain development and commercial rights of STRO-001 globally outside of Greater China, including the United States.

Under the BioNova Option Agreement, BioNova paid the Company an initial licensing option payment of $4.0 million, with potential payments totaling up to $200 million related to option exercise, development, regulatory, and commercial milestones. The Company will provide STRO-001 to BioNova under appropriate clinical and commercial supply service agreements. Upon commercialization, the Company is eligible to receive tiered royalties ranging from low- to mid-teen percentages based on annual net sales of STRO-001 in Greater China for at least ten years following the first commercial sale of STRO-001 in Greater China.

The Company identified a combined performance obligation under the initial license option agreement, which consists of four interrelated promises: generating a recommended dose of STRO-001 for multiple myeloma and Non-Hodgkin’s lymphoma, providing licensed know-how and regulatory filings necessary to prepare an IND; providing initial clinical supply in the People’s Republic of China; and participating in the JSC. These promises are considered to be interdependent and not distinct from each other, representing a combined output. The transaction price at inception included the refundable payment of $4.0 million and was considered constrained at the inception of the agreement since the Company could not conclude it was probable that a significant reversal in the amount of revenue recognized would not occur. BioNova will have the right to exercise the license option for an additional payment of $12.0 million. As of December 31, 2021, there was $4.0 million of deferred revenue related to the payment received by the Company under the BioNova Option Agreement and BioNova had not yet exercised the license option.

Tasly License Agreement

In December 2021, the Company entered into a license agreement with Tasly, to grant Tasly an exclusive license to develop and commercialize STRO-002 in Greater China. Tasly will pursue the clinical development, regulatory approval, and commercialization of STRO-002 in multiple indications, including ovarian cancer, non-small cell lung cancer, triple-negative breast cancer, and other indications in Greater China. The Company will retain development and commercial rights of STRO-002 globally outside of Greater China, including the United States.

Under the Tasly License Agreement, Tasly is obligated to make to the Company an initial nonrefundable upfront payment of $40.0 million, with additional potential payments totaling up to $345 million related to development, regulatory and commercialization contingent payments and milestones. The Company will provide STRO-002 to Tasly under appropriate clinical and commercial supply service agreements. Upon commercialization, the Company will receive tiered royalties, ranging from low- to mid-teen percentages based on annual net sales of STRO-002 in Greater China for at least ten years following the first commercial sale of STRO-002 in Greater China.

The Company determined that the Tasly License Agreement falls within the scope of ASC 808, as both parties are active participants in the activities and are exposed to significant risks and rewards dependent on the success of the commercialization of indications for STRO-002 in Greater China. The Company concluded that the Tasly License Agreement contained the following units of account: i) licensed know-how and Sutro patents, license to trademark rights, and initial regulatory data and information necessary to prepare an IND; and ii) collaboration governance and information sharing activities, such as JSC participation and ongoing regulatory and pharmacovigilance support.

The promises related to the licensed know-how and Sutro patents, license to trademark rights, and initial regulatory data and information necessary to prepare an IND are considered to be interdependent and not distinct from each other, representing a combined output. The Company determined that these promises are capable of being distinct from the collaboration governance and information sharing activities discussed below and further determined that this unit of account is a vendor-customer relationship and will account for it in accordance with ASC 606. The transaction price at inception included fixed consideration consisting of the upfront payment of $40.0 million. All potential future milestones and other payments were considered constrained at the inception of the Tasly License Agreement since the Company could not conclude it was probable that a significant reversal in the amount of revenue recognized would not occur. Since there is only one performance obligation accounted for under ASC 606, no allocation of the transaction price was necessary.

The Company determined that the unit of account consisting of collaboration governance and information sharing activities, such as JSC participation and ongoing regulatory and pharmacovigilance support, do not represent a customer-vendor relationship between the Company and Tasly. These promises are considered to be interdependent and not distinct from each other, representing a combined output. However, the Company determined that these promises are capable of being distinct from the intellectual property and data license promises discussed above. As such, based on the nature of the agreement and collaborative activities, the Company determined that the costs associated with these governance and information sharing activities performed under the agreement will be included in research and development expenses in the statements of operations, with any reimbursement of costs by Tasly reflected as a reduction of such expenses. During the year ended December 31, 2021, the Company did not recognize a reduction of research and development expenses under the Tasly License Agreement.

On December 24, 2021, the effective date of the Tasly License Agreement, the Company satisfied its only performance obligation related to the $40.0 million upfront payment by delivering to Tasly the license, know-how and data required under the Tasly License Agreement. Following the satisfaction of such performance obligation, under the Tasly License Agreement, Tasly is obligated to pay the Company the $40.0 million upfront payment. In February 2022, Tasly indicated to the Company that it would like to discuss and renegotiate the terms of the Tasly License Agreement. As any renegotiation could affect the amount and timing of Tasly’s obligations under the terms of the Tasly License Agreement, including the upfront payment, the Company has concluded that it will not recognize the $40.0 million upfront payment as revenue in December 2021.

6. Property and Equipment, Net

Property and equipment, net, consists of the following:

December 31,

(in thousands)

Computer equipment and software $ 1,353 $ 1,291

Furniture and office equipment 237 680

Less accumulated depreciation and amortization (33,426 ) (36,827 )

Total property and equipment, net $ 22,550 $ 12,935

Depreciation and amortization expense amounted to $4.8 million, $4.3 million and $4.8 million for the years ended December 31, 2021, 2020 and 2019, respectively.

7. Loan and Security Agreement

In August 2017, the Company entered into a loan and security agreement with Oxford Finance LLC (“Oxford”) and Silicon Valley Bank (“SVB”) under which it borrowed $15.0 million (the “August 2017 Loan”). The loan was due in 30 monthly installments from March 2019 through its repayment in August 2021, with interest-only monthly payments until March 2019. The Company commenced repayment of the loan in March 2019. The interest charges on the loan were based on a floating rate that equaled the greater of 7.39% or the sum of the 30-day U.S. Dollar London Interbank Offered Rate (“LIBOR”) plus 6.40%. In connection with the August 2017 Loan, the Company issued to Oxford and SVB a warrant to purchase the Company’s Series D-2 redeemable convertible preferred stock (the “2017 Warrant”). The 2017 Warrants were later converted into warrants to purchase Series E redeemable convertible preferred stock in May and July 2018, and upon the Company’s IPO on October 1, 2018, all Series E redeemable convertible preferred stock warrants were converted to warrants to purchase 46,359 shares of common stock. The estimated fair value upon issuance of the 2017 Warrant of $0.3 million was recorded as a debt discount on the associated borrowings on the Company’s balance sheet. The debt discount was amortized to interest expense over the expected repayment period of the loan using the effective-interest method.

On February 28, 2020, (the “Effective Date”), the Company entered into a loan and security agreement (the “Loan and Security Agreement”) with Oxford as the collateral agent and a lender, and SVB as a lender (together with Oxford, the “Lenders”), pursuant to which the Lenders agreed to lend the Company up to an aggregate of $25.0 million (the “Term A Loan”). Upon entering into the Loan and Security Agreement, the Company borrowed $25.0 million from the Lenders, with approximately $9.6 million of such amount applied to the repayment of the outstanding principal, interest and final payment fees owed pursuant to the August 2017 Loan. As such, the August 2017 Loan has been paid in full. The Company accounted for the issuance of the Loan and Security Agreement and repayment of the August 2017 Loan as a debt modification. The associated unamortized debt discount on the August 2017 Loan and new lender fees from the debt issuance will be amortized as interest expense using the effective interest method until the maturity date of the Term A Loan.

The Company’s obligations under the Loan and Security Agreement are secured by all assets of the Company, other than its intellectual property. The Company has also agreed not to encumber its intellectual property assets, except as permitted by the Loan and Security Agreement.

The Term A Loan matures on March 1, 2024 (the “Maturity Date”) and will be interest-only through March 1, 2022, followed by 24 equal monthly payments of principal and interest.The Term A Loan will bear interest at a floating per annum rate equal to the greater of (i) 8.07% or (ii) the sum of (a) the greater of (1) the thirty (30) day U.S. LIBOR rate reported in the Wall Street Journal on the last business day of the month that immediately precedes the month in which the interest will accrue or (2) 1.67%, plus (b) 6.40%.

The Company will be required to make a final payment of 3.83% of the original principal amount of the Term A Loan, or $1.0 million, payable on the earlier of (i) the Maturity Date, (ii) the acceleration of the Term A Loan, or (iii) the prepayment of the Term A Loan (the “Final Payment”). The final payment amount is accreted as interest expense until the Maturity Date using the effective interest method. The Company may prepay all, but not less than all, of the Term A Loan upon 30 days’ advance written notice to Oxford, provided that the Company will be obligated to pay a prepayment fee equal to (i) 3.00% of the principal amount of the Term A Loan prepaid on or before the first anniversary of the applicable funding date, or (ii) 2.00% of the principal amount of the Term A Loan prepaid between the first and second anniversary of the applicable funding date, or (iii) 1.00% of the principal amount of the Term A Loan prepaid thereafter, and prior to the Maturity Date (each, a “Prepayment Fee”).

The Loan and Security Agreement contains customary affirmative and restrictive covenants, including covenants regarding incurrence of additional indebtedness or liens, investments, transactions with affiliates, delivery of financial statements, maintenance of inventory, payment of taxes, maintenance of insurance, protection of intellectual property rights, dispositions of property, business combinations or acquisitions, among other customary covenants. The Company is also restricted from paying dividends or making other distributions or payments on its capital stock, subject to limited exceptions. The Loan and Security Agreement provides that an event of default will occur if, among other triggers, there occurs any circumstances that could reasonably be expected to result in a material adverse change in the business, or operations or condition (financial or otherwise) of the Company or a material impairment of the prospect of the Company to repay any portion of its obligations under the Agreement. The Agreement also includes customary representations and warranties, other events of default and termination provisions.

In connection with entering into the Loan and Security Agreement, the Company issued to the Lenders warrants exercisable for 81,257 shares of the Company’s common stock (the “2020 Warrants”). The 2020 Warrants are exercisable in whole or in part, immediately, and have a per share exercise price of $9.23, which is the closing price of the Company’s common stock reported on the Nasdaq Global Market on the day prior to the Effective Date. The 2020 Warrants will terminate on the earlier of February 28, 2030 or the closing of certain merger or consolidation transactions. The estimated fair value upon issuance of the Warrants of $0.6 million is recorded as a debt discount on the associated borrowings on the Company’s balance sheet. The debt discount is being amortized to interest expense over the expected repayment period of the loan using the effective-interest method.

As of December 31, 2021 and 2020, accrued interest expense was $0.2 million and $0.2 million, respectively.

During years ended December 31, 2021, 2020 and 2019, the Company recorded interest expense related to loans outstanding of $2.6 million, $2.3 million and $1.1 million, respectively, with average interest rates of 8.07%,8.08% and 8.72%, respectively, and interest related to the accretion of debt discount of $0.6 million, $0.5 million and $0.2 million, respectively.

Long-term debt and net premium (amortization) balances are as follows:

December 31,

(in thousands)

Less: Debt, current portion (9,375 ) -

Future minimum payments of principal and estimated payments of interest on the Company’s Loan and Security Agreement as of December 31, 2021 are as follows:

Year Ending December 31: Amount

(in thousands)

Total future maturities 28,604

Less amount representing interest (2,646 )

Less final payment (958 )

Total principal amount of debt $ 25,000

8. Commitments and Contingencies

Leases

In June 2021, the Company entered into a third amendment (the “Third Amendment”) to its manufacturing facility lease, dated May 18, 2011, as amended, by and between Alemany Plaza LLC, located in San Carlos, California (the “San Carlos Lease”), as an extension to the term of the San Carlos Lease for a period of five years (the “Lease Extension Period”). Pursuant to the Third Amendment, the San Carlos Lease will expire on July 31, 2026, and it includes an option to renew the San Carlos Lease for an additional five years. The aggregate estimated base rent payments due over the Lease Extension Period is approximately $4.2 million, subject to certain terms contained in the San Carlos Lease.

In June 2021, the Company entered into a first amendment (the “First Amendment”) to its manufacturing support facility lease, dated May 4, 2015, as amended, by and between 870 Industrial Road LLC, located in San Carlos, California (the “Industrial Lease”), as an extension to the term of the Industrial Lease for a period of five years (the “Industrial Lease Extension Period”). Pursuant to the first Amendment, the Industrial Lease will expire on June 30, 2026, and it includes an option to renew the Industrial Lease for an additional five years. The aggregate estimated base rent payments due over the Industrial Lease Extension Period is approximately $4.3 million, subject to certain terms contained in the Industrial Lease.

In September 2020, the Company entered into a sublease agreement (the “Sublease”) with Five Prime Therapeutics, Inc. (the “Sublessor”), for approximately 115,466 square feet, in a building located in South San Francisco, California (the “Premises”). The Company uses the Premises as its new corporate headquarters and to conduct (or expand) research and development activities. The Company commenced making monthly payments for the first 85,755 square feet of the Premises (“Initial Premises”) in July 2021, with occupancy of such space commencing in August 2021. The Company was provided early access to the Initial Premises commencing in the fourth quarter of 2020 to conduct certain planning and tenant improvement work. The Sublease is subordinate to the lease agreement, effective December 12, 2016, between the Sublessor and HCP Oyster Point III LLC (the “Landlord”). The commencement date for the remaining 29,711 square feet of the Premises (the “Expansion Premises”) is expected to be 24 months following the commencement date on the Initial Premises, although the Company has the right to accelerate the commencement date on the Expansion Premises to an earlier date upon six months’ prior written notice to the Sublessor. The Sublease for both the Initial Premises and Expansion Premises will expire on December 31, 2027. With a commencement date on the Initial Premises of July 1, 2021,

the aggregate estimated base rent payments due over the term of the Sublease are approximately $39.1 million, including the approximately $5.2 million in potential financial benefit to the Company of base rent abatement to be provided by Sublessor, subject to certain terms contained in the Sublease.The Sublease contains customary provisions requiring the Company to pay its pro rata share of utilities and a portion of the operating expenses and certain taxes, assessments and fees of the Premises and provisions allowing the Sublessor to terminate the Sublease upon the termination of the lease with the Landlord or if the Company fails to remedy a breach of certain of its obligations within specified time periods. Additionally, the Company posted a security deposit of $0.9 million, which is reflected as restricted cash in non-current assets on the Company’s balance sheet as of December 31, 2021 and 2020.

The Company recognizes rent expense for these operating leases on a straight-line basis over the lease period. The components of lease costs, which the Company includes in operating expenses in the statements of operations, were as follows (in thousands):

Year ended December 31,

Operating lease cost $ 8,355

Short-term lease cost 117

Variable lease cost 2,089

During the year ended December 31, 2021, the Company recorded operating lease expense of $8.4 million and paid $6.2 million of operating lease payments related to the lease liabilities, which the Company includes in net cash used in operating activities in the statements of cash flows.

As of December 31, 2021, the weighted-average remaining lease term was 5.7 years and the weighted-average discount rate used to determine the operating lease liability was 10.8%.

As of December 31, 2021, the maturities of the Company’s operating lease liabilities were as follows (in thousands):

Year Ending December 31, Amount

(in thousands)

Total lease payments 45,694

Less: imputed interest (13,433 )

Operating lease liabilities 32,261

Less: current portion (1,037 )

Total lease liabilities, non-current $ 31,224

(1) Includes approximately $5.2 million in potential financial benefit to the Company of base rent abatement to be provided by sublessor for months 7 – 18 of the sublease period, subject to certain terms contained in the Sublease.

Under the historical guidance of ASC 840, the deferred rent balance on December 31, 2020 totaled $1.3 million and the future minimum lease payments for the Company's operating leases on December 31, 2020 were as follows (in thousands):

Year Ending December 31, Amount

(in thousands)

Total future minimum lease payments $ 48,745

(1) Excludes approximately $5.2 million in potential financial benefit to the Company of base rent abatement to be provided by sublessor for months 7 – 18 of the sublease period, subject to certain terms contained in the Sublease.

Rent expense was $4.7 million and $3.6 million for the years ended December 31, 2020 and 2019, respectively.

Indemnification & Other

In the ordinary course of business, the Company may provide indemnifications of varying scope and terms to vendors, lessors, business partners, board members, officers, and other parties with respect to certain matters, including, but not limited to, losses arising out of breach of such agreements, services to be provided by the Company, negligence or willful misconduct of the Company, violations of law by the Company, or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with directors and certain officers and employees that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors, officers or employees. No demands have been made upon the Company to provide indemnification under such agreements, and thus, there are no claims that the Company is aware of that could have a material effect on the Company’s balance sheets, statements of operations, or statements of cash flows. The Company currently has directors’ and officers’ liability insurance.

In addition, the Company enters into agreements in the normal course of business, including with contract research organizations for clinical trials, contract manufacturing organizations for certain manufacturing services, and vendors for preclinical studies and other services and products for operating purposes, which are generally cancelable upon written notice.

9. Related-Party Transactions

Upon the Company’s public offering on May 14, 2020, Merck’s ownership of the Company’s outstanding equity interest decreased to less than 10%. As a result, starting May 14, 2020, the Company ceased to reflect balances and transactions associated with Merck as being with a related party in its financial statements. Transactions with Merck for the years ended December 31, 2021, 2020 and 2019 are described in Note 5.

As discussed in Note 2, Vaxcyte closed its IPO of its common stock on June 16, 2020, resulting in the Company’s ownership of Vaxcyte’s outstanding equity being less than 4.0%. As a result, starting on June 16, 2020, the Company ceased to reflect any balances and transactions associated with Vaxcyte being a related party in its financial statements. Transactions with Vaxcyte for the years ended December 31, 2021, 2020 and 2019 are described in Note 5.

10. Stockholders’ Equity

Common Stock

Holders of common stock are entitled to one vote per share on all matters to be voted upon by the stockholders of the Company.

As of December 31, 2021 and 2020, the Company had reserved common stock, on an if-converted basis, for issuance as follows:

December 31,

Preferred Stock

As of December 31, 2021, the Company had 10,000,000 shares of preferred stock authorized with a par value of $0.001. No shares of preferred stock were outstanding as of December 31, 2021 and 2020.

Warrants

In August 2017, the Company issued warrants to Oxford and SVB to purchase an aggregate of 682,230 shares of Series D-2 redeemable convertible preferred stock at an exercise price of $0.6596 per share in connection with the issuance of the August 2017 Loan. If there was a subsequent convertible preferred stock or other senior equity securities financing with a per share price less than the Series D-2 redeemable convertible preferred per share price, then the warrant would automatically convert to a warrant to purchase such class of shares, based on the per share price of such equity. Given that the price per share of the Series E redeemable convertible preferred stock described above was less than the price per share of the Series D-2 redeemable convertible preferred stock, the 2017 Warrant converted into a warrant to purchase a total of 1,682,871 shares of Series E redeemable convertible preferred stock at an exercise price of $0.2674 per share. The warrant is exercisable from the original date of issuance and has a 10-year term.

The Company adjusted the warrant liability for changes in fair value until the completion of its IPO on October 1, 2018, at which time certain convertible preferred stock warrants were converted into warrants for the purchase of common stock and the related convertible preferred stock warrant liability was reclassified to additional paid-in capital and others expired. On October 1, 2018, 1,232,220 shares of the Series C redeemable convertible preferred warrants were canceled, and the remaining 687,928 shares were converted to 25,453 shares of warrants to purchase common stock on a 1-for-0.0370 basis at an exercise price of $12.9649. The common stock warrant was outstanding and exercisable as of December 31, 2020. In November 2021, this common stock warrant was fully net exercised into 9,308 shares of common stock. All Series E redeemable convertible preferred warrants were converted to 46,359 shares of warrants to purchase common stock on a 1-for-0.0275 basis.

In February 2020, in connection with entering into the Loan and Security Agreement, the Company issued to Oxford and SVB the 2020 Warrants, which are exercisable for 54,171 shares and 27,086 shares, respectively, of the Company’s common stock. The 2020 Warrants are exercisable in whole or in part, immediately, and have a per share exercise price of $9.23, which is the closing price of the Company’s common stock reported on the Nasdaq Global Market on the day prior to the Effective Date. The 2020 Warrants will terminate on the earlier of February 28, 2030 or the closing of certain merger or consolidation transactions.

11. Equity Incentive Plans, Employee Stock Purchase Plan and Stock-Based Compensation

2004 Equity Incentive Plan, 2018 Equity Incentive Plan and 2021 Equity Inducement Plan

In September 2018, the Company adopted the 2018 Equity Incentive Plan (“2018 Plan”), which became effective on September 25, 2018. As a result, the Company will not grant any additional awards under the 2004 Equity Incentive Plan (“2004 Plan”). The terms of the 2004 Plan and applicable award agreements will continue to govern any outstanding awards thereunder. In addition to the shares of common stock reserved for future issuance under the 2004 Plan that were added to the 2018 Plan upon its effective date, the Company initially reserved 2,300,000 shares of common stock for issuance under the 2018 Plan. In addition, the number of shares of common stock reserved for issuance under the 2018 Plan will automatically increase on the first day of January for a period of up to ten years, commencing on January 1, 2019, in an amount equal to 5% of the total number of

shares of the Company’s capital stock outstanding on the immediately preceding December 31 (rounded to the nearest whole share), or a lesser number of shares determined by the Company’s board of directors. As a result, common stock reserved for issuance under the 2018 Plan was increased by 2,287,605 shares on January 1, 2021.

In August 2021, the Company adopted the 2021 Equity Inducement Plan (“2021 Plan”), which became effective on August 4, 2021. Upon its effective date, the Company initially reserved 750,000 shares of common stock for issuance pursuant to non-qualified stock options and restricted stock units (“RSUs”) under the 2021 Plan. In accordance with Rule 5635(c)(4) of the Nasdaq listing rules, equity awards under the 2021 Plan may only be made to an employee if he or she is granted such equity awards in connection with his or her commencement of employment with the Company and such grant is an inducement material to his or her entering into employment with the Company or such subsidiary. In addition, awards under the 2021 Plan may only be made to employees who have not previously been an employee or member of the Board (or any parent or subsidiary of the Company) or following a bona fide period of non-employment of the employee by the Company (or a parent or subsidiary of the Company). At all times the Company will reserve and keep available a sufficient number of shares as will be required to satisfy the requirements of all outstanding awards granted under the 2021 Plan.

As of December 31, 2021, the Company had 1,504,641 shares available for grant under the 2018 Plan and the 2021 Plan.

The following table summarizes option activities under the Company’s 2004 Plan, 2018 Plan and 2021 Plan:

The aggregate intrinsic value was calculated as the difference between the exercise prices of the underlying stock option awards and the estimated fair value of the Company’s common stock on the date of exercise. For the years ended December 31, 2021, 2020 and 2019, the aggregate intrinsic value of stock options exercised was $2.8 million, $1.2 million and $0.2 million, respectively, determined at the date of the option exercise.

Employee Stock Options Valuation

For determining stock-based compensation expense, the fair-value-based measurement of each employee stock option was estimated as of the date of grant using the Black-Scholes option pricing model with assumptions as follows:

Year Ended December 31,

Expected dividend - - -

Expected Term—The expected term represents the period that the stock-based awards are expected to be outstanding. The Company used the “simplified” method to determine the expected term of options granted, which calculates the expected terms as the average of the weighted-average vesting term and the contractual term of the option.

STRO US Equity

STRO · 10-K · period ended 2021-12-31

Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations

Item 7A. Quantitative and Qualitative Disclosures about Market Risk

Item 8. Financial Statements and Supplementary Data

STRO US Equity☆

STRO · 10-K · period ended 2021-12-31

Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations

Item 7A. Quantitative and Qualitative Disclosures about Market Risk

Item 8. Financial Statements and Supplementary Data

STRO US Equity