A Trial to Find Out if REGN5678 (Nezastomig) is Safe and How Well it Works Alone or in Combination With Cemiplimab for Adult Participants With Metastatic Castration-Resistant Prostate Cancer and Other Tumors
← catalyst calendarNCT03972657 · readout in 453 d
Sponsored by Regeneron Pharmaceuticals (industry) · REGN — their whole pipeline →.
Phase
Phase 1/2
Status
Recruiting
Study type
Interventional
Design
Non randomized · None · Treatment
Enrollment
345estimated
Sites
24
Country
United States
Every value on this page is a field the sponsor filed with ClinicalTrials.gov, reproduced. Dates are their own estimates, revised as a study runs, unless the registry marks them actual. sources →
Source: ClinicalTrials.gov, retrieved 2026-08-19
Dates
each axis at the precision it was filed, with the registry's own basis| Date | Filed | Basis | What it is |
|---|---|---|---|
| Start | 2019-08-12 | actual | When the study began enrolling |
| Primary completion | 2027-11-15 | estimated | The date the last participant is measured for the primary outcome — the readout window |
| Study completion | 2027-11-15 | estimated | The whole study's end, after follow-up |
| First posted | 2019-06-03 | actual | When this record first appeared on the registry |
| Results posted | — | When the sponsor posted results to the registry | |
| Record updated | 2026-07-09 | actual | The sponsor's own last edit to this record — every projection above is as current as this date |
What it studies
Conditions
- Metastatic Castration-Resistant Prostate Cancer (mCRPC)
- Clear Cell Renal Cell Carcinoma (ccRCC)
Interventions
- Drug: REGN5678 — also filed as Nezastomig
- Drug: Cemiplimab — also filed as REGN2810, LIBTAYO
Primary outcomes
what the primary-completion date above is the date OFIncidence and severity of Treatment-Emergent Adverse Events (TEAEs)
measured Through study completion, up to 5 years
Incidence and severity of Adverse Event of Special Interests (AESIs)
measured Through study completion, up to 5 years
Incidence and severity of Serious Adverse Events (SAEs)
measured Through study completion, up to 5 years
Number of participants with Grade ≥3 laboratory abnormalities
measured Through study completion, up to 5 years
Incidence of Dose-Limiting Toxicities (DLTs)
measured First dose through day 42 of last participant in each dose level
Concentration of REGN5678 in serum over time
measured Through study completion, up to 5 years
Concentration of REGN5678 in combination with cemiplimab in serum over time
measured Through study completion, up to 5 years
Composite Response Rate (CRR) of 50% decline of Prostate Specific Antigen (PSA) and/or confirmed radiographic response of complete (CR) or partial response (PR)
measured Through study completion, up to 5 years
Objective Response Rate (ORR) per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 criteria
measured Through study completion, up to 5 years
Permalink · REGN's whole pipeline · Catalyst calendar · Every registered study · What changed