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REGN5678

Phase 1

Metastatic Castration-Resistant Prostate Cancer (mCRPC) | Small molecule | Oncology |Regeneron Pharmaceuticals, Inc.|Last Updated: Nov 6, 2025

Success Probability
Approval Probability 71%
TA Base Rate26%
Adjusted LOA41%
ML RiskLOW_RISK
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Market & Valuation
rNPV $3.2B
Market Size $9.4B
Revenue Basis $1.6B
Competitors 6
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Trial Design
CONTROLLEDBiomarker
Total Trials1
Total Enrollment345
FDA Designations
No designations recorded
Clinical Trials (1)
NCT IDTitlePhaseStatusEnrollmentVelocityDesignStartCompletionLast UpdatedSitesCountries
NCT03972657A 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 TumorsPHASE1 RECRUITING 345 — — Aug 12, 2019Nov 15, 2027Nov 6, 202521 United States
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Study Endpoints
Primary Endpoints
Incidence and severity of Treatment-Emergent Adverse Events (TEAEs)
Through study completion, up to 5 years

Dose Escalation Phase

Incidence and severity of Adverse Event of Special Interests (AESIs)
Through study completion, up to 5 years

Dose Escalation Phase

Incidence and severity of Serious Adverse Events (SAEs)
Through study completion, up to 5 years

Dose Escalation Phase

Number of participants with Grade ≥3 laboratory abnormalities
Through study completion, up to 5 years

Dose Escalation Phase

Incidence of Dose-Limiting Toxicities (DLTs)
First dose through day 42 of last participant in each dose level

Dose Escalation Phase

Concentration of REGN5678 in serum over time
Through study completion, up to 5 years

Dose Escalation Phase

Concentration of REGN5678 in combination with cemiplimab in serum over time
Through study completion, up to 5 years

Dose Escalation Phase

Composite Response Rate (CRR) of 50% decline of Prostate Specific Antigen (PSA) and/or confirmed radiographic response of complete (CR) or partial response (PR)
Through study completion, up to 5 years

Dose Expansion Phase - mCRPC cohort

Objective Response Rate (ORR) per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 criteria
Through study completion, up to 5 years

Dose Expansion Phase - ccRCC cohort

Secondary Endpoints
CRR of 50% decline of PSA and/or confirmed radiographic of CR or PR
Through study completion, up to 5 years
ORR per RECIST 1.1 criteria
Through study completion, up to 5 years
Incidence and severity of TEAEs
Through study completion, up to 5 years
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Study Design & Arms
AllocationNON_RANDOMIZED
MaskingNONE
ModelPARALLEL
PurposeTREATMENT
Treatment Arms
ArmTypeDescription
mCRPC - dose escalation cohortEXPERIMENTALREGN5678 with or without cemiplimab
mCRPC - dose expansion cohortEXPERIMENTALREGN5678 with or without cemiplimab
ccRCC - dose escalation cohortEXPERIMENTALREGN5678 with or without cemiplimab
ccRCC - dose expansion cohortEXPERIMENTALREGN5678 with or without cemiplimab
Interventions
NameTypeDescription
REGN5678DRUGAdministered as per the protocol
CemiplimabDRUGAdministered as per the protocol
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Eligibility Criteria
Age Range18 Years — N/A
SexALL
Healthy VolunteersNo
Study Sites21

Key Inclusion Criteria: mCRPC cohorts (men): 1. Men with histologically or cytologically confirmed adenocarcinoma of the prostate without pure small cell carcinoma. 2. PSA value at screening ≥4 ng/mL that has progressed within 6 months prior to screening as defined in the protocol. 3. Has received...

Countries:United States
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Recent Changes (Last 90 Days)
LOWMay 26, 2026NCT03972657primaryCompletionDate: changed
LOWMay 24, 2026NCT03972657studyFirstPostDate: changed