This study is designed to evaluate multiple clinical hypotheses and mechanistically-defined
combinations to evaluate the safety and efficacy of immunotherapy combinations in
participants with mCRPC who have received prior secondary androgen receptor signaling
inhibitor therapy (eg, abiraterone, enzalutamide, apalutamide).
This is an open-label, non-randomized, exploratory platform protocol designed to assess the
safety and antitumor activity of multiple immunotherapy combinations in participants with
mCRPC who have received prior therapy. The platform study will consist of 2 stages: Stage 1,
an initial stage to evaluate safety, biomarkers, and clinical activity of a combination and
Stage 2, an expanded cohort, when warranted, based on the safety, clinical activity, and/or
biomarker results from Stage 1. The Sponsor intends to modify and/or add new combinations to
the protocol as data emerge from this and other trials.
Participants must provide consent for archival tissue from a prior biopsy or surgery for
prostate cancer and must consent to baseline and on-treatment biopsies, if medically
feasible. Participants will be assigned to receive one of the enrolling combination study
interventions and will be monitored for safety and response.
Key Inclusion Criteria:
1. Metastatic castration resistant prostate cancer with castrate-level testosterone (< 50
ng/dL) at screening.
2. Disease progression per Prostate Cancer Working Group 3 (PCWG3) criteria.
3. Provide fresh pre-treatment core needle or incisional biopsy of a metastatic tumor
lesion not previously irradiated. Fine needle aspiration is not acceptable.
1. Additionally, if a pre-treatment biopsy is not medically feasible for
participants with bone only disease, formalin-fixed paraffin-embedded (FFPE)
tumor specimen in a paraffin block (preferred) or at least 10 slides containing
unstained, freshly cut, serial sections must be provided.
2. For all participants, in addition to fresh pre-treatment biopsy, consent for
archival tissue is required.
4. Must be willing to undergo tumor biopsy(ies) on treatment, if medically feasible.
5. Have received and progressed on prior secondary androgen receptor signaling inhibitor
therapy (eg, abiraterone, enzalutamide, apalutamide).
6. Participants must discontinue antiandrogen therapy (ie, bicalutamide, flutamide,
nilutamide) at least 4-6 weeks prior to registration with no evidence of PSA decline
1. Bicalutamide: Washout period at least 6 weeks
2. Flutamide and nilutamide: Washout period at least 4 weeks
7. Participants must discontinue therapies for mCRPC for 5 half-lives or 28 days,
whichever is shorter.
1. Participants will remain on gonadotropin-releasing hormone (GnRH) agents
throughout this study.
2. Prior chemotherapy is allowed if no progression of disease on chemotherapy as
defined by PCWG3-modified RECIST 1.1.
3. Prior treatment with sipuleucel-T, radium-223, or poly ADP ribose polymerase
(PARP) inhibitor (eg, olaparib) is allowed.
4. Tissue biopsy may be performed during washout period.
Key Exclusion Criteria:
1. Has a diagnosis of immunodeficiency or conditions that need systemic corticosteroid
replacement therapy > 10 mg/day prednisone (or equivalent) or other immunosuppressive
medications within 28 days prior to the first dose of study intervention. Inhaled
steroids are permitted if necessary.
2. Has any active known or suspected autoimmune disease. Participants with vitiligo, type
I diabetes mellitus, controlled autoimmune hypothyroidism, psoriasis not requiring
systemic treatment, or other conditions under control are permitted to enroll.
3. Has a known history of active TB (Bacillus Tuberculosis).
4. Has known history of, or any evidence of active, non-infectious pneumonitis.
5. Known history of testing positive for human immunodeficiency virus (HIV), known
acquired immunodeficiency syndrome (AIDS), or any positive test for hepatitis B or
hepatitis C virus representing acute or chronic disease.
6. Has received a live vaccine within 30 days of planned start of study intervention.
Note: Seasonal influenza vaccines for injection are generally inactivated flu vaccines
and are allowed; however intranasal influenza vaccines (eg, Flu-Mist®) are live
attenuated vaccines, and are not allowed.
7. Has known active central nervous system (CNS) metastases and/or carcinomatous
meningitis. Participants with previously treated brain metastases may participate
provided they are stable (without evidence of progression by imaging for at least 4
weeks prior to the first dose of study intervention and any neurologic symptoms have
returned to baseline), have no evidence of new or enlarging brain metastases, and are
not using steroids for at least 7 days prior to study intervention. This exception
does not include carcinomatous meningitis which is excluded regardless of clinical