ATNM US Equity☆

UNITED

STATES

SECURITIES

AND EXCHANGE COMMISSION

Washington,

D.C. 20549

FORM

10-K

(Mark

One)

☒

Annual Report Pursuant To Section 13 or 15(d) Of The Securities Exchange Act Of 1934

For

the fiscal year endedDecember 31, 2025

or

☐

Transition Report Pursuant To Section 13 or 15(d) Of The Securities Exchange Act Of 1934

For

the transition period from _____ to _____

COMMISSION

FILE NUMBER: 001-36374

ACTINIUM

PHARMACEUTICALS, INC.

(Exact

name of registrant as specified in its charter)

100

Park Ave., 23rd Floor

New

York, NY10017

(Address

of principal executive offices) (Zip Code)

(646)677-3870

Registrant’s

telephone number, including area code

Securities

registered pursuant to Section 12(b) of the Act:

Title of each class Trading symbol Name of exchange on which registered

Common stock, par value $0.001 ATNM NYSE American

Securities

registered pursuant to Section 12(g) of the Act: None

Indicate

by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes ☐ No

☒

Indicate

by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes ☐ No

☒

Indicate

by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange

Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2)

has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate

by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule

405 of Regulation S-T (Section 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant

was required to submit such files). Yes ☒ No ☐

Indicate

by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting

company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,”

“smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer ☐ Accelerated filer ☐

Non-accelerated filer ☒ Smaller reporting company ☒

Emerging growth company ☐

If

an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying

with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate

by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness

of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered

public accounting firm that prepared or issued its audit report. ☐

If

securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant

included in the filing reflect the correction of an error to previously issued financial statements. ☐

Indicate

by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation

received by any of the registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b). ☐

Indicate

by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the act): Yes ☐ No ☒

The

aggregate market value of voting stock held by nonaffiliates of the registrant as of June 30, 2025, the last business day of the

registrant’s most recently completed second fiscal quarter, based on the closing price of the common stock on the NYSE American

on June 30, 2025 was $43,663,089.

As of March 30, 2026, 31,374,994 shares of common stock, $0.001 par

value per share, were outstanding.

Table of

Contents

Item 1. Business 1

Item 1A. Risk Factors 33

Item 1B. Unresolved Staff Comments 71

Item 1C. Cybersecurity 71

Item 2. Properties 72

Item 3. Legal Proceedings 72

Item 4. Mine Safety Disclosures 72

Item 6. Reserved 74

Item 7A. Quantitative and Qualitative Disclosures About Market Risk 79

Item 8. Financial Statements and Supplementary Data F-1

Item 9A. Controls and Procedures 80

Item 9B. Other Information 80

Item 9C Disclosure Regarding Foreign Jurisdictions That Prevent Inspections 80

Item 10. Directors, Executive Officers and Corporate Governance 81

Item 11. Executive Compensation 89

Item 12. Security Ownership of Certain Beneficial Owners and Management 97

Item 14. Principal Accountant Fees and Services 98

Item 15. Exhibits, Financial Statement Schedules 99

Signature Page 103

i

CAUTIONARY

NOTE REGARDING FORWARD-LOOKING STATEMENTS

This

Annual Report on Form 10-K (this “Report”) contains forward-looking statements that involve risks and uncertainties, principally

in the sections entitled “Description of Business,” “Risk Factors,” and “Management’s Discussion

and Analysis of Financial Condition and Results of Operations.” All statements other than statements of historical fact contained

in this Report, including statements regarding future events, our future financial performance, business strategy and plans and objectives

of management for future operations, are forward-looking statements. We have attempted to identify forward-looking statements by terminology

including “anticipates,” “believes,” “can,” “continue,” “could,” “estimates,”

“expects,” “intends,” “may,” “plans,” “potential,” “predicts,”

“should,” or “will” or the negative of these terms or other comparable terminology. Although we do not make forward-looking

statements unless we believe we have a reasonable basis for doing so, we cannot guarantee their accuracy. These statements are only predictions

and involve known and unknown risks, uncertainties and other factors, including the risks outlined under “Risk Factors” or

elsewhere in this Report, which may cause our or our industry’s actual results, levels of activity, performance or achievements

expressed or implied by these forward-looking statements. Moreover, we operate in a very competitive and rapidly changing environment.

New risks emerge from time to time and it is not possible for us to predict all risk factors, nor can we address the impact of all factors

on our business or the extent to which any factor, or combination of factors, may cause our actual results to differ materially from

those contained in any forward-looking statements. All forward-looking statements included in this document are based on information

available to us on the date hereof, and we assume no obligation to update any such forward-looking statements.

You

should not place undue reliance on any forward-looking statement, each of which applies only as of the date of this Report. Before you

invest in our securities, you should be aware that the occurrence of the events described in the section entitled “Risk Factors”

and elsewhere in this Report could negatively affect our business, operating results, financial condition and stock price. Except as

required by law, we undertake no obligation to update or revise publicly any of the forward-looking statements after the date of this

Report to conform our statements to actual results or changed expectations.

ii

PART I

ITEM 1. BUSINESS.

Description of Our Business

We are a clinical-stage biopharmaceutical company pioneering the development

of targeted radiotherapies to address significant unmet medical needs in oncology. We are focused on employing a biology-driven approach

to develop differentiated, first-in-class radiopharmaceutical therapeutics for patients with solid tumors and hematologic malignancies.

Our mission is to transform cancer treatment by delivering innovative radioconjugates that maximize therapeutic efficacy while minimizing

toxicity to healthy tissue by combining our deep understanding of tumor biology and translational medicine with our expertise in radiochemistry.

Since our inception, we

have focused on developing innovative and differentiated radiotherapies. Our pipeline of both early and later stage development

programs is a testimony to our approach in three areas with: (1) two novel solid tumor product candidates, ATNM-400 and Actimab-A,

with pan-tumor potential, (2) Actimab-A, which is also being developed as a therapeutic backbone for acute myeloid leukemia (AML)

and myelodysplastic syndrome (MDS) in partnership with the National Cancer Institute (NCI), and (3) two targeted conditioning

agents, Iomab-B for bone marrow transplant and Iomab-ACT for cell & gene therapies. Our solid tumor asset, ATNM-400, targets a

novel, antigen which does not target PSMA, with demonstrated pre-clinical activity across metastatic castration-resistant prostate

cancer (mCRPC), non-small cell lung cancer (NSCLC), and breast cancer. Actimab-A, targets myeloid derived suppressor cells

(MDSC’s) and is being studied in multiple solid tumors in combination with immune checkpoint inhibitors where MDSC’s are

known to act as an efficacy deterrent for these agents. Our hematology franchise includes: Actimab-A, a CD33-targeted therapy; as

well as, Iomab-B and Iomab-ACT which are CD45-targeting conditioning agents. Both Actimab-A and Iomab-B are Phase 2/3 ready assets and are

supported by extensive validation in over 15 clinical trials in which more than 500 patients were treated.

The

radiopharmaceutical therapeutics market has experienced significant growth and validation in recent years. The FDA approvals of

Pluvicto® (177Lu-PSMA-617) for prostate cancer and Lutathera® (177Lu-DOTATATE) for gastroenteropancreatic

neuroendocrine tumors (GEP-NETs) have demonstrated the transformative potential of targeted radiotherapy.

Pluvicto® is the first radiopharmaceutical to achieve blockbuster status and generated approximately

$2 billion in sales in 2025 and is forecast by its sponsor Novartis to reach peak sales of $5 billion. Lutathera® is also

forecasted to attain blockbuster status by Novartis.

1

Many companies have entered the space, perhaps attracted by the success

of the aforementioned products and also the acquisitions of several companies in recent years. However, most companies have focused on

just a handful of targets. Consequently, we believe the radiopharmaceutical field remains in its early stages despite the number of companies

now developing radiotherapies. This is apparent as a majority of the radiotherapy industry development pipeline is clustered around a

handful of biological targets with most companies focused on prostate-specific membrane antigen (PSMA), somatostatin receptor type 2 (SSTR2)

antagonists/agonists and variations on the theme (NSTR2, NSTR3, etc), and fibroblast activation protein (FAP). Each of these targets features

multiple programs using different targeting moieties including but not limited to peptides, small molecules, antibodies as well as various

isotope payloads including beta emitters like Lutetium-177 and alpha emitters such as Actinium-225 and Lead-212.

In contrast, we see a significant opportunity to broaden the patient populations benefiting from targeted radiopharmaceuticals by coupling

our understanding of tumor biology and translational medicine with our expertise in radiochemistry to develop novel programs against differentiated

targets with multi-indication potential. From 2013 to 2023, there was approximately $17 billion in high-value mergers and acquisitions

focused on radiopharmaceutical assets, capabilities and infrastructure. Six major pharmaceutical companies have a established radiotherapy

presence via acquisitions, resulting in approximately 300,000 square feet of radiopharmaceutical manufacturing infrastructure which is

largely underutilized as there are just three approved radiopharmaceutical therapeutics. Since 2024, there has been $8 billion in strategic

investments and licensing transactions specifically targeting assets that offer novelty and differentiation in the radiotherapy space.

We believe this activity demonstrates both the validation of radiotherapies as a viable treatment modality and the larger companies urgent

need for truly differentiated assets to fill their pipelines.

2

Our Competitive Strengths

We believe we are well-positioned to capitalize on the radiopharmaceutical

opportunity based on the following competitive strengths:

Biology-Driven Approach to Radiopharmaceutical Development

We employ a

biology first approach to identify targets that are implicated in underlying tumor biology, disease

progression and/or treatment resistance. In doing so, we believe our targeted radiotherapies are

differentiated from the rest of the radiopharmaceutical industry pipeline and have first-in-class potential. The recent acquisitions and

licensing transactions in the radiopharmaceutical field have been driven by novel assets and platforms beyond targets such as PSMA, SSTR

and FAP. To our knowledge, ATNM-400 and Actimab-A MDSC are the only radiopharmaceuticals in development pursuing their respective targets

and indications. Similarly, Actimab-A, Iomab-B and Iomab-ACT, are the only CD33 and CD45 targeting

radiotherapies in clinical development to our knowledge. We will continue to identify and evaluate novel radiopharmaceutical assets leveraging

our biology-driven methodology.

Differentiated, First-in-Class Pan-Tumor Programs Addressing Large

Solid Tumor Indications

Our pipeline features multiple

first-in-class programs targeting novel antigens not currently addressed by existing radiopharmaceutical platforms. ATNM-400 represents

a differentiated approach in prostate cancer by targeting a non-PSMA antigen, potentially addressing patients who do not respond to or

progress after PSMA-targeted therapy such as Pluvicto®, as well as enabling earlier line combinations with androgen receptor pathway

inhibitors (ARPIs). With demonstrated pre-clinical efficacy across prostate cancer, NSCLC, and breast cancer, ATNM-400 has pan-tumor potential

addressing a combined patient population exceeding 800,000 in the United States. Our pre-clinical data demonstrate that ATNM-400 outperformed

leading approved therapies by 3-5 fold in EGFR-mutant NSCLC models as a monotherapy in terms of tumor growth inhibition, produced cures

in combination with Tagrisso®, and achieved complete tumor regression in combination with Herceptin® in HER2-resistant breast

cancer models.

Actimab-A represents another differentiation

opportunity through its mechanism of depleting CD33+ MDSCs, potentially unlocking synergy with PD-1

checkpoint inhibitors such as Keytruda® and Opdivo® in MDSC-rich solid tumors. This approach

addresses a well-documented mechanism of PD-1 resistance, with clinical data demonstrating that high MDSC levels correlate with poor outcomes

on PD-1 therapy. This positions Actimab-A to potentially expand the $40+ billion PD-1 inhibitor market.

De-Risked Late-Stage Hematology Franchise with Near-Term Partnership

Potential

Our hematology programs are supported by extensive clinical validation

and represent potential near-term value creation opportunities. Iomab-B has been evaluated in over 500 patients across multiple clinical

trials and has received FDA alignment on a Phase 2/3 trial design in an expanded relapsed/refractory (R/R) AML patient population. The

program benefits from composition of matter patents extending into 2037, an existing network of 24 clinical sites with continued interest

from the Study of Iomab-B in Elderly Relapsed Refractory AML (SIERRA) trial, and potential market expansion across six disease indications

representing approximately 150,000 addressable patients who can benefit from improved bone marrow transplant conditioning.

Actimab-A has demonstrated what we believe to be compelling clinical

data in combination with CLAG-M chemotherapy, achieving high rates of measurable residual disease (MRD) negativity and improved survival

outcomes in high-risk R/R AML patients. In Phase 1b clinical trials, patients treated with Actimab-A plus CLAG-M achieved a 24-month median

overall survival among the 70% who proceeded to bone marrow transplant, comparing favorably to the less than 2-4 month overall survival

typically observed in TP53-positive or prior venetoclax-treated patient populations. We have received FDA alignment on Phase 2/3 trial

design for Actimab-A in combination with CLAG-M for R/R AML patients and are actively seeking strategic partnerships to advance these

programs.

3

The targeted conditioning franchise,

including Iomab-B for bone marrow transplant and Iomab-ACT for cell and gene therapies, addresses the fundamental challenge of establishing

donor cell engraftment while reducing toxicities associated with traditional chemotherapy based myeloablative

conditioning regimens. Iomab-ACT has the potential to serve as a universal conditioning agent, improving patient access and outcomes for

CAR-T and other cell therapies, with three active clinical trials currently underway.

End-to-End Supply Chain and Demonstrated

Ability to Execute Complex Clinical Trials

Our clinical assets have been studied in over 500 patients to date

and we have executed multiple Phase 1 – 3 clinical trials across our Actimab-A, Iomab-ACT and Iomab-ACT programs. In doing so, we

have established and actively managed an end-to-end supply chain that encompasses sourcing of radioisotopes, manufacturing targeting agents,

production of final drug product candidates and their delivery to the point of care. We believe our demonstrated ability to execute radiopharmaceutical

trials at approximately 50 treatment centers including leading comprehensive cancer centers can be leveraged for our ongoing and planned

clinical development efforts. We executed a phase 3 trial of Iomab-B which utilized extremely high doses of Iodine-131 (I-131) which required

specialized handling. Additional operational parameters included the need for patient isolation in a transplant setting which added to

the complexity of the trial yet the company successfully executed the trial without missing a single dose. We are exploring improved methods for efficiently generating quality clinical data by working with centers of excellence both in and outside

the United States. We believe these capabilities

have strategic value to enable the successful and timely clinical execution of our own planned trials for product candidates we may in-license,

partner or acquire.

Vertically Integrated Capabilities and Infrastructure

We are in the process of establishing comprehensive end-to-end capabilities across the radiopharmaceutical value chain. We have invested

in establishing an operational radiopharmaceutical manufacturing facility expected to be commissioned in 2H:2026, which will provide clinical

supply capabilities by year-end. This facility, combined with our established distribution network to approximately 50 leading hospitals

and multiple redundant isotope supply agreements, positions us to serve patient demand at scale. Our proprietary cyclotron-based Ac-225

production technology for which we are seeking a partnership, can help us secure reliable isotope supply at commercial scale via an internal

back-up source. We believe our manufacturing process achieves radiochemical purity equivalent to the gold-standard thorium decay method

without generating long-lived radioactive contaminants. We have demonstrated leading-edge pre-clinical radiochemistry and translational

biology capabilities that enable rapid advancement from target selection through clinical development. This vertical integration provides

us with significant strategic flexibility and insulates us from supply chain disruptions that have historically challenged radiopharmaceutical

development.

Strong Intellectual Property Position

We have built an intellectual

property portfolio comprising approximately 250 issued patents and pending patent applications, including critical composition of matter

patents, method of use patents, and proprietary Ac-225 production technology. Our intellectual property estate provides extensive protection

for our product candidates and platform technologies across major global markets, with issued and pending patent coverage over key programs.

We believe our IP position creates substantial barriers to entry and positions our assets as attractive opportunities for strategic partnerships

and out-licensing.

4

Our Strategy

Our goal is to establish Actinium as

a leading, fully integrated targeted radiotherapy company delivering transformative medicines to cancer patients.

Key elements of our strategy include:

Rapidly Advance ATNM-400 Through Clinical Development Across Multiple

Indications

We are focused on rapidly advancing

ATNM-400 into clinical development, leveraging the pre-clinical validation we have established across multiple solid tumor indications.

In mCRPC, the pre-clinical dataset demonstrating mechanistic synergy with ARPI’s such as enzalutamide, superiority to both single-agent

enzalutamide and 177Lu-PSMA-617, and strong combination activity supports the therapeutic potential in this indication. Based on this

data, we believe ATNM-400, a non-PSMA targeting radioconjugate, demonstrates the potential to benefit patients who progress on or are

ineligible for PSMA-targeted therapy and potentially enable earlier-line combination approaches with ARPIs.

ATNM-400 also demonstrates clinical development

potential in EGFR-mutant NSCLC, where our pre-clinical data demonstrated 3-5 fold superiority compared

to approved EGFR inhibitors including osimertinib (Tagrisso®), datopotamab deruxtecan (Dato-DXd),

and amivantamab, as well as 100% complete responses in combination with osimertinib. We have established mechanistic rationale for this

combination through demonstrated upregulation of the ATNM-400 target following osimertinib treatment. Furthermore, in pre-clinical

studies, both ATNM-400 monotherapy and ATNM-400 in combination with osimertinib is superior to an osimertinib combination with chemotherapy.

This positions ATNM-400 for potential development across first-, second-, and third-line EGFR-mutant NSCLC

treatment settings.

In breast cancer, we have demonstrated

efficacy across HR-positive, triple-negative breast cancer (TNBC), and HER2-resistant models, with complete tumor eradication observed

for ATNM-400 in combination with trastuzumab (Herceptin®) in trastuzumab-resistant models. The ATNM-400 target shows increased expression

in trastuzumab-resistant tumors, providing mechanistic support for clinical development in this setting. We believe ATNM-400 represents

a differentiated approach that can avoid the off-target toxicities such as interstitial lung disease observed with HER2 and TROP-2 antibody-drug

conjugates such as Ehertu® and Datroway®, respectively.

5

Establish Actimab-A MDSC in Combination with Checkpoint Inhibitors

We currently intend to conduct a basket trial evaluating Actimab-A

in combination with PD-1 inhibitors (Keytruda® or Opdivo®) across four MDSC-rich solid tumor types: head and neck squamous cell

carcinoma (HNSCC), NSCLC, glioblastoma (GBM), and high microsatellite instability (MSI-high) colorectal cancer. This trial, expected to

report initial data in 2H:2026, is supported by pre-clinical evidence demonstrating that Actimab-A selectively homes to and depletes tumor-resident

CD33+ MDSCs, which are primed for depletion and correlate with poor outcomes on PD-1 therapy. Our pre-clinical data show that Actimab-A

treatment is cytotoxic to patient-derived MDSCs ex vivo and enhances T-cell responses.

The trial design includes comprehensive

biomarker assessments to evaluate MDSC depletion patterns in both tumor microenvironment and peripheral blood, as well as T-cell activity

restoration. We will compare clinical outcomes including objective response rate (ORR), progression-free survival (PFS), and overall survival

(OS) against real-world data comparators. Success in this trial could position Actimab-A as a foundational combination partner for checkpoint

inhibitors across multiple solid tumor indications. In addition, we are evaluating the potential for further clinical evaluation of Actimab-A

in patients with GBM and NSCLC with other PD-1 inhibitors.

GBM has a unique microenvironment in which ~40% of the glioma mass is comprised of tumor associated myeloid (TAM’s) cells which

play an important role in immunosuppression and inhibition of anti-tumor responses. Selective eradication of these TAM’s which express

CD33 within the GBM tumor microenvironment with Actimab-A has the potential to enhance anti-tumor T-cell immunity thereby increasing the

effectiveness of immunotherapies for the treatment of GBM.

Execute Strategic Partnerships for Late-Stage Hematology Programs

We are actively seeking strategic partnerships to advance our Phase

2/3-ready hematology programs, Actimab-A and Iomab-B. These programs benefit from substantial clinical validation, clear regulatory pathways

following FDA alignment, and concentrated commercial markets focused on approximately 100 quaternary care centers in the United States

and Europe. The complementary nature of these programs—spanning AML/MDS therapeutics and targeted conditioning for bone marrow transplant

and cell/gene therapies—creates strong commercial synergies and represents blockbuster market opportunities.

Our partnership strategy prioritizes collaborations that can provide

the resources and infrastructure necessary to execute global pivotal trials while preserving meaningful economics for Actinium. We are

leveraging our existing relationship with the National Cancer Institute (NCI), which has established a Cooperative Research and Development

Agreement (CRADA) supporting Actimab-A development, to advance clinical programs in a cost-effective manner while retaining commercial

rights.

Build Fully Integrated cGMP Manufacturing and End-to-End Supply Chain

We are completing construction

of our internal cGMP radiopharmaceutical manufacturing facility, which is being designed to manufacture Ac-225 based radioconjugates and

provide drug product manufacturing to support clinical trials. This facility, expected to be operational in 2H:2026, will complement our

established network of hospital administration sites and isotope suppliers. Our hybrid internal-external manufacturing strategy is designed

to provide supply reliability, cost efficiency, and geographic flexibility to serve global patient populations at commercial scale. In

addition, we will opportunistically seek partnerships to manufacture Ac-225 utilizing our patented cyclotron production technology.

6

Continue Platform Innovation and Pipeline Expansion

We are committed to continued innovation

in radiopharmaceutical discovery and development. Our proven track record of generating highly differentiated programs positions us to

expand our pipeline through both internal discovery efforts and potential strategic acquisitions of complementary assets or technologies.

We maintain rigorous criteria for program advancement, requiring demonstration of clear differentiation, compelling pre-clinical

validation, and significant market opportunities before committing substantial resources to clinical development.

Our Pipeline

Solid Tumor Programs

ATNM-400: First-in-Class Pan-Tumor Radiotherapy

ATNM-400 is our lead solid tumor program,

representing a first-in-class Ac-225 antibody radioconjugate targeting a novel, undisclosed, non-PSMA targeting antigen with expression

across multiple solid tumor types. The ATNM-400 target is implicated

in disease biology during tumor progression and is also overexpressed when tumors become resistant

to many approved therapies in multiple solid tumors.

7

Our pre-clinical translational

data demonstrated that ATNM-400 is superior to:

● PSMA-targeted agents or ARPI’s in the mCRPC setting of prostate cancer

These data show that ATNM-400 works well as monotherapy but is even

better in combination in resistant settings where the target is overexpressed as part of the resistance mechanism. Evidence of target

expression has been observed ranging from 60%-80%+ in mCRPC, NSCLC, and breast cancer patient tumors, representing a significant addressable

population of over a hundred thousand patients in the United States based on our existing datasets. This number may expand as we continue

our work to demonstrate the potential of ATNM-400 in various additional disease and treatment settings.

Our pre-clinical development program has generated robust efficacy

and mechanism-of-action data across multiple indication-specific animal models:

Prostate Cancer: ATNM-400 demonstrated

specific tumor uptake and decreased tumor cell proliferation in pre-clinical models, with significantly

greater efficacy than both 177Lu-PSMA-617 (the active agent in Pluvicto®) and next-generation

225Ac-PSMA-617 in PSMA-low 22Rv1 prostate cancer xenograft models that are resistant to ARPI therapy.

8

Importantly, ATNM-400 also demonstrated superior efficacy to enzalutamide

and 177Lu-PSMA-617 in ARPI-resistant prostate cancer models, with strong and durable combination activity when combined with enzalutamide.

This combination activity is mechanistically supported by our observation that enzalutamide resistance increases ATNM-400 target expression

in both prostate cancer models and mCRPC patient samples.

9

These

data support ATNM-400 development in post-Pluvicto® and post-ARPI patient populations. Between 45,000 to 55,000 patients will progress

on ARPI in the mCRPC and metastatic hormone sensitive prostate cancer (mHSPC) settings annually. With a potential of Pluvicto®

approval in mHSPC based on the Phase 3 PSMAddition study, the number of eligible patients nearly doubles from 44,000 patients in the

mCRPC population to 86,500 patients in both mHSPC and mCRPC. Given that the response rates for Pluvicto® in the VISION and PSMAfore

population are approximately 30% and 50%, respectively, a significant proportion of patients remain with few options following treatment.

Additionally, Pluvicto® refractory patients will receive as few as 2 cycles if no response is observed. The mechanistic synergy with

ARPIs also supports potential expansion to earlier treatment lines in combination with standard-of-care hormonal therapies, representing

an addressable population exceeding 100,000 patients across all lines of treatment in the mCRPC and mHSPC settings.

EGFR-Mutant NSCLC: ATNM-400 demonstrated 3-5 fold greater tumor growth

inhibition compared to approved EGFR-targeted therapies including osimertinib (first-line), datopotamab deruxtecan (second-line), and

amivantamab (third-line) in NCI-H1975 human lung cancer models harboring L858R and T790M EGFR mutations.

10

In combination with osimertinib, ATNM-400 achieved 100% complete responses

with durable efficacy extending throughout the study period.

We have established mechanistic support for ATNM-400 combinations with

EGFR inhibitors, demonstrating that osimertinib treatment increases ATNM-400 target expression both in vitro and in vivo. This mechanistic

synergy, combined with clinical data showing improved outcomes when osimertinib is combined with external beam radiotherapy, supports

ATNM-400 development across multiple EGFR-mutant NSCLC treatment settings.

11

EGFR-mutant

NSCLC represents approximately 30,000 U.S. patients annually, with current treatment dominated by

AstraZeneca’s Tagrisso® (osimertinib) and Johnson & Johnson’s Rybrevant®

(amivantamab) combinations. ATNM-400 offers a novel EGFR inhibitor plus radiotherapy combination approach

with potential differentiation across first-, second-, and third-line settings. Additionally, given tumor cell apoptosis driven by the

irreversible double-stranded DNA damage from actinium-225, ATNM-400 could potentially provide benefit for the approximately 200,000 NSCLC

patients diagnosed annually regardless of oncogenic driver mutation.

Breast Cancer: ATNM-400 demonstrated

robust anti-tumor activity and tumor regression as monotherapy and in combination with trastuzumab in pre-clinical breast

cancer models, including trastuzumab-resistant BT474-Clone5 model, HR+ breast cancer MCF-7 model and triple-negative breast cancer

(TNBC) and triple-negative MDA-MB-468 model. In the trastuzumab-resistant

setting, we observed increased expression of both the survival pathway marker p-AKT and the ATNM-400 target, with ATNM-400 treatment inducing

DNA double-strand breaks as measured by p-H2AX staining. ATNM-400 achieved 66% tumor growth inhibition as monotherapy and 103% tumor growth

inhibition (representing tumor regression) in trastuzumab-resistant models.

12

The ATNM-400 target is overexpressed in breast cancer, including tumors

resistant to endocrine therapies such as tamoxifen and HER2-targeted therapies, as well as in TNBC.

13

We believe that this broad expression pattern supports multi-lineage

development in breast cancer. Current second-line therapies in HER2-positive disease, including trastuzumab deruxtecan and sacituzumab

govitecan, are limited by off-target toxicities including interstitial lung disease. ATNM-400 represents a novel therapeutic approach

designed to avoid these toxicity concerns while providing efficacy across HR-positive, HER2-resistant, and TNBC patient populations representing

approximately 300,000 U.S. patients annually.

We have developed a theranostic strategy utilizing Zr-89 as a companion

imaging agent to enable patient selection and tumor visualization. This approach allows for non-invasive assessment of target expression

and drug biodistribution prior to therapeutic administration, potentially enhancing the therapeutic index by selecting patients most likely

to respond.

Success in our clinical program could position ATNM-400 as a differentiated

pan-tumor targeted radiotherapy across multiple large solid tumor indications, potentially addressing the several hundred thousand U.S.

patients with mCRPC, EGFR-mutant NSCLC, and all sub-types of breast cancer, while also establishing a first-in-class radioconjugate with broad combination potential and

attractive partnership and commercial potential in the rapidly growing radiopharmaceutical market.

Actimab-A for MDSC’s: Novel Immunomodulatory Approach in Solid

Tumors

Actimab-A (lintuzumab-Ac-225) is a CD33-targeted Ac-225 radioconjugate

that we are developing to enhance checkpoint inhibitor efficacy by depleting immunosuppressive CD33+ MDSCs in the tumor microenvironment.

MDSCs are a heterogeneous population of immature myeloid cells that

accumulate in solid tumors and suppress anti-tumor T-cell responses, representing a well-validated mechanism of resistance to PD-1/PD-L1

checkpoint inhibitors. Clinical studies have demonstrated that patients with high circulating MDSC levels have significantly reduced progression-free

and overall survival on PD-1 therapy compared to patients with low MDSC levels.

14

Low MDSC’s Associated with Statistically Significant

Improvement in PFS and OS

Source: 1) Bronte et al. High Levels of Circulating Monocytic Myeloid-Derived

Suppressive-Like Cells Are Associated With the Primary Resistance to Immune Checkpoint Inhibitors in Advanced Non-Small Cell Lung Cancer:

An Exploratory Analysis https://pmc.ncbi.nlm.nih.gov/articles/PMC9043492/. Frontiers in Immunology. 2022 Apr 13;13:866561

Our pre-clinical studies

have demonstrated that Actimab-A: (1) selectively homes to tumor-resident CD33+ MDSCs in vivo; (2) is cytotoxic to patient-derived MDSCs

ex vivo; and (3) rescues T-cell proliferation and anti-tumor immune responses ex vivo following MDSC depletion. These data provide mechanistic

support for combining Actimab-A with PD-1 inhibitors to overcome MDSC-mediated resistance.

We intend to conduct a Phase 1b basket

trial evaluating Actimab-A in combination with pembrolizumab (Keytruda®) or nivolumab (Opdivo®)

in patients with R/R locally advanced or metastatic HNSCC, NSCLC, GBM, and MSI-high colorectal cancer. These

tumor types were selected based on high MDSC infiltration and limited response rates to PD-1 monotherapy. The trial design incorporates

comprehensive correlative biomarker assessments to evaluate MDSC depletion in both tumor microenvironment and peripheral blood, as well

as T-cell activity restoration.

Patients enrolled in the trial

must have MDSC-rich tumor types, be checkpoint inhibitor-naïve, be at least 18 years of age, and demonstrate PD-1/PD-L1 expression.

Primary endpoints include safety and tolerability of the combination, with secondary endpoints including ORR, PFS, and OS. Biomarker endpoints

will evaluate the pattern of CD33+ MDSC depletion and T-cell activity in both tumor tissue and peripheral blood samples. Clinical outcomes

will be compared against real-world data from similar patient populations treated with PD-1 monotherapy. We expect to report initial data

from this trial in 2H:2026. In addition, we are also evaluating clinical opportunities with other immune checkpoint inhibitors in GBM

and NSCLC.

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We believe that success in this trial could position Actimab-A for

development across multiple solid tumor indications in combination with checkpoint inhibitors, potentially expanding the utility of the

$40+ billion PD-1/PD-L1 inhibitor market by addressing MDSC-mediated resistance.

Hematology Programs

Actimab-A: Backbone Therapy for AML and MDS

In hematologic malignancies, we are developing

Actimab-A as a mutation-agnostic backbone therapy for AML and high-risk MDS. CD33 is expressed on leukemic blasts in the majority of AML

patients and represents an established therapeutic target validated by the approval of gemtuzumab ozogamicin (Mylotarg®). However,

antibody-drug conjugates like Mylotarg® have limitations including hepatotoxicity and limited

efficacy in certain patient populations. Actimab-A, delivering the highly potent alpha-emitter Ac-225 to CD33+ cells, represents a differentiated

approach designed to provide superior efficacy while maintaining a favorable safety profile.

Actimab-A in combination with

CLAG-M for R/R AML: We have completed a Phase 1b clinical trial evaluating Actimab-A in combination with CLAG-M chemotherapy in R/R AML

patients, results of which were published in a peer-reviewed journal Leukemia in February 2025. The

trial enrolled high-risk patients including those with TP53 mutations, prior venetoclax treatment failure, and patients who had

prior allogeneic transplant. Results demonstrated high rates of MRD-negative complete remissions and improved

survival outcomes compared to historical controls.

Among patients treated with Actimab-A

plus CLAG-M, 70% of those deemed eligible for transplant proceeded to bone marrow transplant, and

this population achieved a 24-month median overall survival. These results compare highly favorably to published data showing less than

2-4 month median overall survival in TP53-mutated or prior venetoclax-treated R/R AML patient populations. The combination was well-tolerated

with a safety profile consistent with CLAG-M chemotherapy alone and no dose-limiting toxicities observed.

Based on these results, we have received FDA alignment on a Phase 2/3

trial design to evaluate Actimab-A plus CLAG-M in first or second salvage R/R AML patients.

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We are currently actively seeking a strategic partner to execute this

trial. The trial design allows for enrollment of a broad R/R AML population while enriching for patients most likely to benefit based

on Phase 1b results.

Actimab-A Development Programs:

Beyond R/R AML, we are developing Actimab-A in conjunction with the NCI across multiple AML and MDS treatment settings and exploring its

potential in additional areas:

The programs are supported

by our Cooperative Research and Development Agreement (CRADA) with the National Cancer Institute, which enables cost-effective clinical

development while retaining commercial rights to Actinium.

We believe that success in our hematology program could establish Actimab-A

as a mutation-agnostic backbone therapy for R/R AML and high-risk MDS, addressing a combined patient population with limited treatment

options, while generating important data to support regulatory approval and to enable a strategic partnership to commercialize Actimab-A

across the estimated $2+ billion AML/MDS therapeutics market.

Iomab-ACT: Universal Conditioning for Cell and Gene Therapies

Iomab-ACT is our CD45-targeted conditioning platform being developed

as a universal conditioning agent to improve access and outcomes for cell and gene therapies, including CAR-T, allogeneic hematopoietic

stem cell transplant, and gene therapy. The cell and gene therapy field has been limited by the need for lymphodepleting chemotherapy

conditioning, which is associated with significant toxicities and can limit the patient populations eligible for these potentially curative

treatments.

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Iomab-ACT is designed to provide targeted

lymphodepletion and myeloablation when necessary while avoiding the off-target toxicities associated

with chemotherapy conditioning. By delivering targeted radiation specifically to CD45+ hematopoietic cells, Iomab-ACT aims to create an

optimal environment for therapeutic cell engraftment while minimizing treatment-related morbidity and mortality.

We currently have three active clinical trials evaluating Iomab-ACT:

The cell and gene therapy market represents a rapidly growing opportunity,

with over 30,000 patients annually receiving CAR-T or allogeneic transplant in the United States and Europe. Success in these trials could

position Iomab-ACT as a universal conditioning platform applicable across multiple cell and gene therapy modalities, potentially expanding

patient access to these curative therapies while improving safety and tolerability.

Iomab-B: Targeted Conditioning for Bone Marrow Transplant in R/R

AML

Iomab-B (apamistamab-I-131) is a CD45-targeted radioimmunotherapy designed

to enable bone marrow transplant in R/R AML patients who are ineligible for conventional myeloablative conditioning due to age, comorbidities,

or prior treatment-related toxicities. CD45 is expressed on all hematopoietic cells, enabling Iomab-B to deliver targeted radiation to

bone marrow while sparing non-hematopoietic organs from radiation exposure.

Conventional stem cell transplant

conditioning regimens utilize high-dose chemotherapy with or without total body irradiation to ablate the patient’s hematopoietic system

and create space for donor cell engraftment. These regimens are associated with significant toxicities including mucositis, hepatotoxicity,

pulmonary toxicity, and treatment-related mortality. Many elderly patients and those with comorbidities are deemed ineligible for these

intensive conditioning regimens, limiting access to potentially curative transplant therapy.

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Iomab-B has been evaluated in over 500

patients across multiple clinical trials, including the Phase 3 SIERRA trial in R/R AML patients. The SIERRA trial demonstrated that Iomab-B

enabled successful donor cell engraftment in elderly R/R AML patients who would otherwise be ineligible for conventional conditioning.

The study met the primary endpoint of durable complete remission

(dCR). While the study did not meet the secondary endpoint of OS due to the cross over of two-thirds of the patients from the control

arm to Iomab-B arm, it provided important insights into optimal patient selection and trial design for future

development.

We have received FDA alignment on a Phase

2/3 trial design in an expanded R/R AML patient population that includes all patients age 18 and older with R/R AML. This

expanded population reflects learnings from SIERRA regarding optimal patient selection. The trial design allows us to leverage both the

Phase 2 results and the SIERRA database to support regulatory submissions.

Iomab-B benefits from composition of matter patents extending to 2038,

a well-established network of 24 clinical sites from the SIERRA trial that maintains strong interest in the program, and potential for

market expansion beyond R/R AML. Pre-clinical and clinical data support potential development in five additional disease indications including

acute lymphoblastic leukemia, myelodysplastic syndromes, chronic myeloid leukemia, multiple myeloma, and lymphoma, representing a total

addressable market of approximately 150,000 patients who could benefit from improved bone marrow transplant conditioning.

We are actively seeking a strategic partner to advance Iomab-B through

pivotal development and commercialization.

We believe Actimab-A,

Iomab-B and Iomab-ACT collectively have the potential to be successful commercial products based on the high unmet needs of their addressable

patient segments. In total, we believe this opportunity exceeds 400,000 patients in the U.S. and EU.

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Our Platform and Capabilities

Radiochemistry and Translational Science Capabilities

We have assembled a team with expertise in radiopharmaceutical discovery

and development, spanning target selection, radioconjugate design, pre-clinical evaluation, and clinical development. Our capabilities

include:

These capabilities enable us to efficiently

advance programs from target selection through clinical development while maintaining high quality standards and generating comprehensive

translational data packages to guide clinical development and support

regulatory submissions and partnership discussions.

Ac-225 Production and Radiopharmaceutical Manufacturing

We have developed proprietary

cyclotron-based technology for commercial-scale production of Ac-225, one of the most critical bottlenecks in radiopharmaceutical development.

Our production method generates high-purity Ac-225 with radiochemical purity equivalent to the gold-standard thorium-229 decay method,

while avoiding the generation of long-lived radioactive contaminants such as Ac-227. This production technology is protected by patents

and if operationalized may represent a significant competitive and cost advantage.

We are currently completing

construction of a radiopharmaceutical manufacturing facility designed to manufacture Ac-225-based final drug products for clinical supply.

The facility, expected to be operational in 2H:2026, incorporates purpose-built infrastructure for alpha-emitter handling and a flexible

manufacturing suite capable of supporting multiple trials.

We have also established an end-to-end supply chain spanning isotope

production through patient administration. We maintain supply agreements with multiple redundant isotope suppliers, relationships with

multiple contract manufacturing organizations, and a distribution network to approximately 50 leading cancer centers amassed via the execution

of several Phase 1 – 3 clinical trials. This supply chain infrastructure provides geographic coverage across major metropolitan

areas, minimizes risk of supply disruption, and positions us to reliably serve patient demand at clinical scale.

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Competition

The radiopharmaceutical therapeutics field has experienced significant

growth in recent years, with numerous companies and academic institutions developing targeted radiotherapy programs. We face competition

from several categories of organizations:

Large Pharmaceutical Companies: Several

major pharmaceutical companies have entered the radiopharmaceutical space through acquisitions or internal development, including Novartis

(through acquisition of Advanced Accelerator Applications and Endocyte ), Eli Lilly (through acquisition

of Point Biopharma), Bristol Myers Squibb (through acquisition of RayzeBio), AstraZeneca (through acquisition of Fusion Pharmaceuticals),

Bayer (through acquisition of Algeta Pharmaceuticals, Noria Therapeutics, and PSMA Therapeutics),

and Johnson & Johnson. These companies possess significantly greater financial resources, established

commercial infrastructure, and broader development pipelines than we do. However, many of these companies are focused on PSMA-targeted

therapies for prostate cancer or SSTR2-targeted therapies for neuroendocrine tumors and have stated a need for novel differentiated assets

to expand their radiopharmaceutical portfolios.

Clinical-Stage Radiopharmaceutical Companies:

We compete with several clinical-stage companies developing novel radiopharmaceutical approaches. A representative list of these

competitors include Telix Pharmaceuticals, Perspective Therapeutics, Clarity Pharmaceuticals, Cellectar Biosciences, Bicycle Therapeutics,

Molecular Partners, Ratio Therapeutics, Convergent Therapeutics, Aktis Oncology, Radiopharm Theranostics, and Plus Therapeutics. This

is not a comprehensive list and none of these or any other radiotherapeutics company currently compete

are directly with Actinium’s product candidates in terms of biological targets.

Antibody-Drug Conjugate Companies:

Particularly solid tumors, we may compete with companies developing antibody-drug conjugates (ADCs) that

deliver cytotoxic chemotherapy payloads to tumor cells. However, we believe radiopharmaceuticals offer potential advantages compared to

ADCs including the “crossfire” or “bystander” effect wherein alpha particles can kill neighboring tumor cells that

do not express the target antigen, potentially overcoming tumor heterogeneity. Additionally, radiopharmaceuticals enable non-invasive

imaging to assess target expression and drug biodistribution, potentially improving patient selection.

Therapeutic Area Competitor Companies: Several large pharmaceutical

companies are legacy areas in the therapeutic areas that our pipeline agents are being developed. In prostate cancer, several marketed

drugs are available from Johnson & Johnson, Astellas/Pfizer, Bayer, Novartis, and AstraZeneca/Merck. AstraZeneca, Johnson & Johnson,

Roche, and Daiichi Sankyo have approved agents in EGFR mutant NSCLC. As for breast cancer, Roche, Pfizer, Lilly, Novartis, and AstraZeneca/Daiichi

Sankyo have therapeutics available. AbbVie, Bristol Myers Squibb, Astellas, and Servier are primary companies with AML marketed agents.

In addition, these companies have active pipelines exploring a multitude of mechanisms of action to maintain or grow their positions in

these indications.

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We believe our competitive position is differentiated by: (1) our focus

on novel, first-in-class targets with pan-tumor potential rather than following validated targets already being pursued by multiple competitors;

(2) our vertically integrated capabilities that we intend to span isotope production through drug product manufacturing; (3) our late-stage

hematology programs with clear regulatory pathways; and (4) our comprehensive intellectual property position protecting our products and

platform technologies.

However, we face significant competitive

risks. Our competitors may develop therapies that are more effective, safer, more convenient, or more cost-effective than our product

candidates. Competitors may also obtain regulatory approval before we do, establish superior market positions, or render our technologies

obsolete. In the evolving landscape of targeted radiotherapies, mergers and acquisitions and collaborations can quickly reshape

the competitive landscape. Large radiopharmaceutical companies are increasingly partnering with and acquiring small biotechnology companies

in the field to access novel pipeline agents and manufacturing capabilities for radiopharmaceutical production and development. These

deals and partnerships, through increased access to capital, regulatory expertise, and global infrastructure, can expedite clinical development

timelines and hasten drug commercialization. The radiopharmaceutical field is characterized by rapid technological

change and intense competition, and we cannot guarantee that we will be able to maintain our competitive position.

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