for males ages 18 years and up (full criteria)
study started
estimated completion



A phase 1 study evaluating the safety, tolerability, pharmacokinetics, and efficacy of prostate specific membrane antigen half-life extended bispecific T-cell engager acapatamab in subjects with metastatic castration-resistant prostate cancer, and to determine the maximum tolerated dose (MTD) or recommended phase 2 dose (RP2D).

Official Title

A Phase 1 Study Evaluating the Safety, Tolerability, Pharmacokinetics, and Efficacy of Prostate Specific Membrane Antigen Half-life Extended Bispecific T-cell Engager Acapatamab in Subjects With Metastatic Castration-resistant Prostate Cancer


This is a phase I, first-in-human study to evaluate the safety and tolerability of acapatamab; a half-life extended (HLE) bispecific T-cell engager (BiTE®) construct, alone and in combination with pembrolizumab, etanercept prophylaxis and cytochrome P450 (CYP) phenotyping cocktail in subjects with metastatic castration-resistant prostate cancer.


Metastatic Castration-resistant Prostate Cancer Prostate Cancer acapatamab HLE-BiTE® mCRPC PSMA BiTE® Bispecific T-Cell engager Immunotherapy Immuno-oncology Immunooncology Solid tumor PSMA Targeted Therapy Prostatic Neoplasms Etanercept Pembrolizumab Immune Checkpoint Inhibitors Cytochrome P450 (CYP) Cocktail


For males ages 18 years and up

All Parts

Inclusion Criteria:

  • Subject has provided informed consent prior to initiation of any study specific activities/procedures
  • Subjects with histologically or cytologically confirmed mCRPC who are refractory to a novel antiandrogen therapy (abiraterone, enzalutamide, and/or apalutamide) and have failed at least 1 (but not more than 2) taxane regimens (or who are deemed medically unsuitable to be treated with a taxane regimen or have actively refused treatment with a taxane regimen). Progression on novel antiandrogen therapy may have occurred in the non-metastatic CRPC setting
  • Subjects must have undergone bilateral orchiectomy or must be on continuous ADT with a gonadotropin releasing hormone (GnRH) agonist or antagonist
  • Total serum testosterone </= 50 ng/dL or 1.7 nmol/L
  • Evidence of progressive disease, defined as 1 or more PCWG3 criteria:
  • PSA level >/= 1 ng/mL that has increased on at least 2 successive occasions at least 1 week apart
  • nodal or visceral progression as defined by RECIST 1.1 with PCGW3 modifications
  • appearance of 2 or more new lesions in bone scan
  • Eastern Cooperative Oncology Group (ECOG) performance status of 0 - 1
  • Life expectancy >/= 6months

Exclusion Criteria:

  • Any anticancer therapy or immunotherapy within 4 weeks of start of first dose, not including luteinizing hormone-releasing hormone agonist (LHRH)/GnRH analogue (agonist/antagonist). Subjects on a stable bisophosphonate or denosumab regimen for >/= 30 days prior to randomization are eligible
  • Prior PSMA-targeted therapy (subjects on prior therapy may be eligible if discussed with Amgen medical monitor prior to enrollment)
  • Central nervous system (CNS) metastases, leptomeningeal disease, or spinal cord compression
  • Active autoimmune disease or any other diseases requiring immunosuppressive therapy while on study
  • Needing chronic systemic corticosteroid therapy (prednisone > 10 mg per day or equivalent) or any other immunosuppressive therapies (including anti-tumor necrosis factor alpha [TNF alpha] therapies) unless stopped 7 days prior to start of first dose
  • Myocardial infarction, unstable angina, cardiac arrhythmia requiring medication, and/or symptomatic congestive heart failure (New York Heart Association > class II) within 12 months of first dose of acapatamab

Part 2 only:

  • Subjects on a prior PD-1 or PD-L1 inhibitor who experienced a Grade 3 or higher immune-related adverse event prior to first day of dosing
  • History or evidence of interstitial lung disease or active, non-infectious pneumonitis

Part 3 only:

  • Evidence of active tuberculosis on chest radiograph within 3 months prior to the first dose of investigational product

Part 6 only:

Subjects are excluded from this cohort if any of the following additional criteria apply:

  • Subjects taking strong OAT3 inhibitors (eg, probenecid) or adjust the dosing to 1 mg PO QD.
  • Subjects with latent or active tuberculosis at screening


  • University of California Los Angeles accepting new patients
    Los Angeles California 90095 United States
  • City of Hope at Long Beach Elm accepting new patients
    Long Beach California 90813 United States


accepting new patients
Start Date
Completion Date
AmgenTrials clinical trials website
Phase 1 research study
Study Type
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