NCT07850921Not yet recruitingPhase 1/2
REGN21353 Alone or in Combination With Nezastomig for Metastatic Castration-Resistant Prostate Cancer in Adult Participants
Phase 1/2 Trial of REGN21353 (a STEAP1xCD3 Bispecific Antibody) Administered Alone or in Combination With Nezastomig (a PSMAxCD28 Bispecific Antibody) in Participants With Metastatic Castration-Resistant Prostate Cancer (mCRPC)
Source: ClinicalTrials.gov · Last updated 30 Sept 2026
Brief summary (registry, in English)
This study will test an experimental Regeneron drug called REGN21353 ("study drug") to see if it can help treat previously treated prostate cancer that has spread (also called metastatic castration-resistant prostate cancer or mCRPC). Some participants may get additional experimental drugs in combination with REGN21353. These additional drugs are nezastomig and sarilumab. "Experimental" means that the drugs are being tested and have not been approved for use in prostate cancer by a country's national health agency that gives approval for new medicines to be prescribed. The study is looking at: * What is the best dose of REGN21353 alone and together with nezastomig for treating prostate cancer * What side effects REGN21353 alone and together with nezastomig might cause * How well REGN21353 alone and together with nezastomig works * How much REGN21353 alone and together with nezastomig is in the blood at different times * If the body reacts to REGN21353 alone or together with nezastomig, in a way that may cause them to not work as well * How REGN21353 alone and together with nezastomig could affect prostate cancer, which can help researchers understand why REGN21353 alone or together with nezastomig work better in some than others
- Status (registry)
- Not yet recruiting
- Phase (registry)
- Phase 1/2
- Study type
- Interventional
- Enrollment
- 192 (estimated)
- First submitted
- 23 Sept 2026
- Start date
- 28 Jun 2027
- Primary completion date
- 28 Jul 2031
- Lead sponsor
- Regeneron Pharmaceuticals
- Diseases
- Prostate cancer
- NCT number
- NCT07850921
What you commit to
- Study type: Interventional · Phase 1/2
- Planned participants: 192
- From 28 Jun 2027 to the primary completion date, 28 Jul 2031
- No sites listed in no country
- Visits and tests: ask the trial team, the registry does not list them
Built from the registry fields of ClinicalTrials.gov. It describes the study, not your situation.
Who cannot take part
Copied verbatim from ClinicalTrials.gov and grouped by topic. Only the trial team decides who can take part.
Prior treatment
- Has not recovered (ie, grade ≤1 or baseline) from immune-mediated adverse event within 3 months prior to initiation of trial intervention therapy except for endocrinopathies adequately managed with hormone replacement
- Has another malignancy that is progressing or requires active treatment, except non-melanoma skin cancer that has undergone potentially curative therapy or any tumor that has been deemed to be effectively treated with definitive local control
- Has ongoing or recent (within 5 years) evidence of significant autoimmune disease (including any history of systemic vasculitis) that required treatment with systemic immunosuppressive treatments
- Has encephalitis, meningitis, neurodegenerative disease (with the exception of mild dementia that does not interfere with activities of daily living), or uncontrolled seizures in the year prior to first dose of trial intervention
- Has active or recent infection requiring hospitalization or treatment with intravenous anti-infectives within 2 weeks of first dose of trial intervention
Other illness
- Has permanently discontinued anti-cancer immune modulating therapies due to immune-mediated adverse events
- Has current evidence of or history of central nervous system metastases as described in the protocol
- Has a known history of, or any evidence of, interstitial lung disease or active, noninfectious pneumonitis (past 5 years). A history of radiation pneumonitis in the radiation field is permitted
- Has significant cardiovascular disease
- Note: Other protocol defined Inclusion/ Exclusion criteria apply
Other
- Has active liver metastases
Who the study is looking for
- Is male with histologically or cytologically confirmed adenocarcinoma of the prostate without pure small cell carcinoma
- Has metastatic castration-resistant prostate cancer with prostate-specific antigen value as described in the protocol and that has progressed within 6 months prior to screening
- Has received ≥2 lines of prior systemic therapy approved in the metastatic and/or castration-resistant setting (in addition to androgen deprivation therapy) including at least one androgen receptor pathway inhibitor (eg, abiraterone, enzalutamide, apalutamide, or darolutamide)
- Has had either orchiectomy or be on luteinizing hormone-releasing hormone (LHRH) agonist or antagonist therapy with serum testosterone levels as described in the protocol and agree to stay on LHRH agonist or antagonist therapy during the trial
- Is able and willing to provide tumor tissue, either archival or newly obtained
- Has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
- Has adequate organ, bone marrow, renal and hepatic function
Age in the registry: 18 years to - · Sex: Male · Does not accept healthy volunteers
This page is information, not medical advice. Discuss any trial with your doctor.