Safety and Efficacy of Therapies for Metastatic Castration-resistant Prostate Cancer (mCRPC)

A Master Protocol Evaluating the Safety and Efficacy of Therapies for Metastatic Castration-resistant Prostate Cancer (mCRPC)

This is a master protocol designed to evaluate the safety and efficacy of investigational therapies in participants with metastatic castration-resistant prostate cancer (mCRPC).

Study Overview

• Status: Terminated
• Conditions: Metastatic Castration-resistant Prostate Cancer
• Intervention / Treatment: Drug: Acapatamab; Drug: Enzalutamide; Drug: Abiraterone; Drug: AMG 404

Detailed Description

This is a master protocol designed to evaluate the safety, tolerability, and maximum tolerated dose (MTD) or recommended phase 2 dose (RP2D) and efficacy of Acapatamab, in combination with enzalutamide, abiraterone, or the PD1 inhibitor AMG 404, AMG 404 monotherapy, as well as Acapatamab monotherapy, in participants with metastatic castration-resistant prostate cancer (mCRPC).

• Study Type: Interventional
• Enrollment (Actual): 55
• Phase: Phase 2; Phase 1

Contacts and Locations

Study Locations

• Australia
  • New South Wales
    • Darlinghurst, New South Wales, Australia, 2010
      • St Vincents Hospital Sydney
• Denmark
  • København Ø, Denmark, 2100
    • Rigshospitalet
• Spain
  • Navarre
    • Pamplona, Navarre, Spain, 31008
      • Clinica Universidad de Navarra
• Sweden
  • Lund, Sweden, 221 85
    • Skånes universitetssjukhus
  • Stockholm, Sweden, 171 76
    • Karolinska Universitetssjukhuset Solna
  • Uppsala, Sweden, 75185
    • Akademiska sjukhuset
• United Kingdom
  • Sutton, United Kingdom, SM2 5PT
    • Royal Marsden Hospital
• United States
  • Alabama
    • Birmingham, Alabama, United States, 35294
      • University of Alabama at Birmingham
  • California
    • Orange, California, United States, 92868
      • University of California at Irvine Medical Center
    • San Francisco, California, United States, 94158
      • University of California San Francisco Mission Bay Campus
  • Illinois
    • Chicago, Illinois, United States, 60637
      • University Of Chicago
  • Kentucky
    • Louisville, Kentucky, United States, 40207
      • Norton Cancer Institute
  • Texas
    • Dallas, Texas, United States, 75390
      • University of Texas Southwestern Medical Center
    • Houston, Texas, United States, 77030
      • University of Texas MD Anderson Cancer Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 99 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

All parts

Inclusion Criteria:

• ≥ 18 years of age (or legal adult age within country)
• Subject has provided informed consent prior to initiation of any study-specific activities/procedures
• Subjects with mCRPC with histologically or cytologically confirmed adenocarcinoma of the prostate
• Subjects should have undergone bilateral orchiectomy or should be on continuous androgen deprivation therapy with a gonadotropin releasing hormone agonist or antagonist (testosterone ≤ 50 ng/dL (or 1.7 nmol/L))

Exclusion Criteria:

• Central nervous system (CNS) metastases or leptomeningeal disease
• History or presence of clinically relevant CNS pathology
• Confirmed history or current autoimmune disease or other diseases requiring permanent immunosuppressive therapy
• Myocardial infarction, uncontrolled hypertension, unstable angina, cardiac arrhythmia requiring medication, and/or symptomatic congestive heart failure (New York Heart Association > class II) within 12 months
• Prior treatment with a taxane for mCRPC
• Major surgery and/or Radiation within 4 weeks

• History or evidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection unless agreed upon with medical monitor and meeting the following criteria:

  • Negative test for SARS-CoV-2 RNA by real time polymerase chain reaction (RT-PCR) within 72 hours of first dose of Acapatamab (or AMG 404 in Part 3)
  • No acute symptoms of COVID-19 disease within 10 days prior to first dose of Acapatamab (or AMG 404 in Part 3) (counted from day of positive test for asymptomatic subjects)

Prior/Concurrent Clinical Study Experience

• Currently receiving treatment in another investigational device or drug study, or less than 4 weeks since ending treatment on another investigational device or drug study(ies). Other investigational procedures while participating in this study are excluded with the exception of investigational scans.

Subprotocol A only:

Inclusion criteria

• Subjects planning to receive enzalutamide for the first time for mCRPC

Exclusion criteria

• Use of strong CYP2C8 inhibitors or strong CYP3A4 inducers
• Use of narrow therapeutic index drugs that are substrates of CYP3A4, CYP2C9 or CYP2C19

Subprotocol B only:

Inclusion criteria

• Subjects planning to receive abiraterone for the first time for mCRPC Exclusion criteria
• Baseline moderate and severe hepatic impairment (Child-Pugh Class B and C)
• Presence of uncontrolled hypertension, hypokalemia, or fluid retention
• History or presence of adrenocortical insufficiency
• Use of concomitant medications that are sensitive substrates for CYP2D6 with a narrow therapeutic index
• Use of strong CYP3A4 inducers

Subprotocol C only:

Inclusion criteria

• Subjects who are refractory to a novel antiandrogen therapy. Subjects must be ineligible for or refuse taxane therapy.
• 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, and/or appearance of 2 or more new lesions in bone scan Exclusion criteria
• History or evidence of interstitial lung disease or active, non-infectious pneumonitis
• 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 dose

Subprotocol D only:

Inclusion criteria

• Subjects may have had novel hormonal therapies (NHT; eg, abiraterone, enzalutamide, apalutamide, or darolutamide) for prostate cancer, but no more than 1 NHT for metastatic prostate cancer
• Ineligible for or refuse taxane therapy

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Sequential Assignment
• Masking: None (Open Label)

Number of Arms

11

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Acapatamab and Enzalutamide: Dose Exploration; The dose-exploration part of the study will estimate the MTD/recommended phase 2 dose (RP2D) of Acapatamab in combination with enzalutamide.	Drug: Acapatamab; Acapatamab will be administered as an intravenous (IV) infusion.; Other Names: PSMA targeted therapy; Drug: Enzalutamide; Enzalutamide will be administered orally.; Other Names: Androgen receptor inhibitor
Experimental: Acapatamab and Enzalutamide: Dose Expansion; Following dose exploration, dose expansion will be conducted to confirm the safety and tolerability of the selected dose and to further evaluate the efficacy of Acapatamab in combination with enzalutamide.	Drug: Acapatamab; Acapatamab will be administered as an intravenous (IV) infusion.; Other Names: PSMA targeted therapy; Drug: Enzalutamide; Enzalutamide will be administered orally.; Other Names: Androgen receptor inhibitor
Experimental: Acapatamab and Abiraterone: Dose Exploration; The dose exploration part of the study will estimate the MTD/recommended phase 2 dose (RP2D) of Acapatamab in combination with abiraterone.	Drug: Acapatamab; Acapatamab will be administered as an intravenous (IV) infusion.; Other Names: PSMA targeted therapy; Drug: Abiraterone; Abiraterone will be administered orally.; Other Names: Cytochrome P450 (CYP)17 inhibitor
Experimental: Acapatamab and Abiraterone: Dose Expansion; Following dose exploration, dose expansion will be conducted to confirm the safety and tolerability of the selected dose and to further evaluate the efficacy of Acapatamab in combination with abiraterone.	Drug: Acapatamab; Acapatamab will be administered as an intravenous (IV) infusion.; Other Names: PSMA targeted therapy; Drug: Abiraterone; Abiraterone will be administered orally.; Other Names: Cytochrome P450 (CYP)17 inhibitor
Experimental: Acapatamab and AMG 404: Dose Exploration; The dose-exploration part of the study will estimate the MTD/RP2D of Acapatamab in combination with AMG 404.	Drug: Acapatamab; Acapatamab will be administered as an intravenous (IV) infusion.; Other Names: PSMA targeted therapy; Drug: AMG 404; AMG 404 will be administered as an intravenous (IV) infusion.; Other Names: PD-1 inhibitor
Experimental: Acapatamab and AMG 404: Dose Expansion; Following dose exploration, dose expansion will be conducted to confirm the safety and tolerability of the selected dose and to further evaluate the efficacy of Acapatamab in combination with AMG 404.	Drug: Acapatamab; Acapatamab will be administered as an intravenous (IV) infusion.; Other Names: PSMA targeted therapy; Drug: AMG 404; AMG 404 will be administered as an intravenous (IV) infusion.; Other Names: PD-1 inhibitor
Active Comparator: AMG 404 Monotherapy; AMG 404 monotherapy is being conducted to evaluate the preliminary anti-tumor activity of PD-1 inhibition in the mCRPC population.	Drug: AMG 404; AMG 404 will be administered as an intravenous (IV) infusion.; Other Names: PD-1 inhibitor
Experimental: Acapatamab and Enzalutamide: Dose Expansion Asia Cohort; Following dose exploration, dose expansion will be conducted in the Asia cohort at the combination MTD/RP2D determined in dose exploration to confirm the safety, tolerability and PK of Acapatamab in combination with enzalutamide for subjects in Asia.	Drug: Acapatamab; Acapatamab will be administered as an intravenous (IV) infusion.; Other Names: PSMA targeted therapy; Drug: Enzalutamide; Enzalutamide will be administered orally.; Other Names: Androgen receptor inhibitor
Experimental: Acapatamab and Abiraterone: Dose Expansion Asia Cohort; Following dose exploration, dose expansion will be conducted in the Asia cohort at the combination MTD/RP2D determined in dose exploration to confirm the safety, tolerability and PK of Acapatamab in combination with abiraterone for subjects in Asia.	Drug: Acapatamab; Acapatamab will be administered as an intravenous (IV) infusion.; Other Names: PSMA targeted therapy; Drug: Abiraterone; Abiraterone will be administered orally.; Other Names: Cytochrome P450 (CYP)17 inhibitor
Experimental: Acapatamab and AMG 404: Dose Expansion Asia Cohort; Following dose exploration, dose expansion will be conducted in the Asia cohort at the combination MTD/RP2D determined in dose exploration to confirm the safety, tolerability and PK of Acapatamab in combination with AMG 404 for subjects in Asia.	Drug: Acapatamab; Acapatamab will be administered as an intravenous (IV) infusion.; Other Names: PSMA targeted therapy; Drug: AMG 404; AMG 404 will be administered as an intravenous (IV) infusion.; Other Names: PD-1 inhibitor
Experimental: Acapatamab Monotherapy; Acapatamab monotherapy is being conducted to evaluate safety, tolerability, pharmacokinetics (PK), pharmacodynamics, and efficacy of Acapatamab in subjects with mCRPC.	Drug: Acapatamab; Acapatamab will be administered as an intravenous (IV) infusion.; Other Names: PSMA targeted therapy

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Subprotocols A, B and C (Parts 1 and 2): Number of Participants Who Experienced a Dose-limiting Toxicity (DLT)	DLTs were defined as any adverse event (AE) (per Common Terminology Criteria for Adverse Events (CTCAE) v5: Grade 5=Death, Grade 4=Life-threatening, Grade 3=Moderate) occurring within 28 days of the first AMG 160 dose, possibly related to the treatment, including: Grade 5 toxicity; Grade 4 thrombocytopenia; Grade 3 thrombocytopenia with significant hemorrhage; Grade 4 neutropenia > 5 days; Febrile neutropenia; Grade 3 anemia requiring transfusion; Grade ≥3 non-hematologic toxicity (with exceptions per protocol); Aspartate transaminase/alanine transaminase >3x upper limit of normal (ULN) with serum total bilirubin >2x ULN without cholestasis or another clear cause; Grade ≥3 non-hematological toxicity delaying treatment > 2 weeks or resulting in <75% dose administration. The complete list of DLTs are described in the protocol	Cycle 1: Day 1 to Day 28 (28-day cycle)
Subprotocols A, B and C (Parts 1 and 2): Number of Participants Who Experienced Treatment-emergent Adverse Events (TEAEs) and Treatment-related AEs	A TEAE was defined as any untoward medical occurrence in a clinical trial participant irrespective of a causal relationship with the trial treatment that started on or after first dose of investigational product (AMG 160 or AMG 404 for Part 1 and 2; AMG 404 for Part 3). A treatment-related TEAE was defined as a TEAE that had a reasonable possibility of being caused by acapatamab, or AMG 404 (subprotocol C, parts 1 and 2 only). Clinically significant changes from baseline in vital signs and clinical laboratory tests were also recorded as TEAEs.	From first dose of acapatamab/AMG 404 to the first of 30 days after last dose of acapatamab/AMG404, end of trial date or the initiation of a new anticancer therapy; median (min, max) duration was 4.665 (0.33, 25.17) months
Subprotocol D: Number of Participants Who Experienced TEAEs and Treatment-related AEs	A TEAE was defined as any untoward medical occurrence in a clinical trial participant irrespective of a causal relationship with the trial treatment that started after the first dose of acapatamab. A treatment-related TEAE was defined as a TEAE that had a reasonable possibility of being caused by acapatamab. Clinically significant changes from baseline in vital signs and clinical laboratory tests were also recorded as TEAEs.	From first dose of acapatamab to the first of 30 days after last dose of acapatamab, end of trial date or the initiation of a new anticancer therapy, whichever is earlier; median (min, max) duration was 4.665 (0.33, 25.17) months
Subprotocol C, Part 3: Objective Response Rate (ORR)	Objective Response is defined as a complete response (CR) or partial response (PR) per RECIST 1.1, confirmed by a repeat assessment at least 4 weeks later. Participants who did not experience a confirmed CR or PR, or did not have any follow-up tumor assessments were regarded as non-responders.	From Cycle 1 Day 1 until progression, start of new anticancer therapy, or end of trial median (min, max) duration was 6.14 (0.14, 105.14) weeks
Subprotocol C, Part 3: Percentage of Participants Who Experienced a Circulating Tumor Cell 0 (CTC0) Response	CTC0 response was defined as CTC0 (reduction of CTCs > 0 to 0 at any post-baseline measurement). The baseline was defined as the last non-missing value on or prior to the pre-dose of AMG 404 assessments on Cycle 1 Day 1.	Cycle 1 Day 1 to 14 days post-last dose of AMG 404 (each cycle was 28 days, maximum duration of AMG 404 treatment was 105.1 weeks)
Subprotocol C, Part 3: Percentage of Participants Who Experienced a CTC Conversion Response	CTC conversion response was defined as ≥ 5 CTCs/7.5 mL blood at baseline that converted to ≤ 4 CTCs/7.5 mL blood at any post-baseline measurement. The baseline was defined as the last non-missing value on or prior to the pre-dose assessments of AMG 404 on Cycle 1 Day 1.	Cycle 1 Day 1 to 14 days post-last dose of AMG 404 (each cycle was 28 days, maximum duration of AMG 404 treatment was 105.1 weeks)
Subprotocol C, Part 3: Percentage of Participants Who Experienced a Prostate Specific Antigen (PSA) Response	A PSA response was defined as the below and must have been confirmed by a second consecutive value 3 weeks later: PSA 30 response: ≥ 30% reduction from the baseline PSA.; PSA 50 response: ≥ 50% reduction from the baseline PSA.; PSA 70 response: ≥ 70% reduction from the baseline PSA.; PSA 90 response: ≥ 90% reduction from the baseline PSA. The baseline was defined as the last non-missing value on or prior to the pre-dose of AMG 404 assessments on Cycle 1 Day 1.	Cycle 1 Day 1 to 5 months post-last dose of AMG 404 (each cycle was 28 days, maximum duration of AMG 404 treatment was 105.1 weeks)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Subprotocols A. B, C (Parts 1 and 2) and D: ORR	Objective Response is defined as a CR or PR per RECIST 1.1, confirmed by a repeat assessment at least 4 weeks later. Participants who did not experience a confirmed CR or PR, or did not have any follow-up tumor assessments were regarded as non-responders.	From Cycle 1 Day 1 until progression, start of new anticancer therapy, or until end of trial (each cycle was 28 days, maximum duration of acapatamab treatment was 98.43 weeks/AMG 404 treatment was 105.14 weeks)
Subprotocols A, B, C (Parts 1 and 2) and D: Percentage of Participants Who Experienced a CTC0 Response	CTC0 response was defined as CTC0 (reduction of CTCs > 0 to 0 at any post-baseline measurement). The baseline was defined as the last non-missing value on or prior to the pre-dose of acapatamab assessments on Cycle 1 Day 1 > 0.	From Cycle 1 Day 1 until progression, start of new anticancer therapy, or until end of trial (each cycle was 28 days, maximum duration of acapatamab treatment was 98.43 weeks/AMG 404 treatment was 105.14 weeks)
Subprotocols A, B, C (Parts 1 and 2) and D: Percentage of Participants Who Experienced a CTC Conversion Response	CTC conversion response was defined as ≥ 5 CTCs/7.5 mL blood at baseline that converted to ≤ 4 CTCs/7.5 mL blood at any post-baseline measurement. The baseline was defined as the last non-missing value on or prior to the pre-dose of acapatamab assessments on Cycle 1 Day 1.	From Cycle 1 Day 1 until progression, start of new anticancer therapy, or until end of trial (each cycle was 28 days, maximum duration of acapatamab treatment was 98.43 weeks/AMG 404 treatment was 105.14 weeks)
Subprotocols A, B, C (Parts 1 and 2) and D: Percentage of Participants Who Experienced a PSA Response	A PSA response was defined as the below and must have been confirmed by a second consecutive value 3 weeks later: PSA 30 response: ≥ 30% reduction from the baseline PSA.; PSA 50 response: ≥ 50% reduction from the baseline PSA.; PSA 70 response: ≥ 70% reduction from the baseline PSA.; PSA 90 response: ≥ 90% reduction from the baseline PSA. The baseline was defined as the last non-missing value on or prior to the pre-dose of acapatamab assessments on Cycle 1 Day 1.	Cycle 1 Day 1 to 5 months post-last dose of acapatamab/AMG 404 (each cycle was 28 days, maximum duration of acapatamab treatment was 98.43 weeks/AMG 404 treatment was 105.14 weeks)
Subprotocols A, B, C (Parts 1, 2 and 3) and D: Duration of CTC0 Response	Duration of CTC0 response was defined as the time from the date of initial CTC0 response to the earlier of CTC0 progression or death. Participants who had not ended their response at the time of analysis had duration of CTC0 response censored on the date of their last CTC0 or CTC conversion assessment.	From date of initial CTC0 response to the earlier of CTC0 progression or death (maximum duration of acapatamab treatment was 98.43 weeks/AMG 404 treatment was 105.14 weeks)
Subprotocols A, B, C (Parts 1, 2 and 3) and D: Duration of CTC Conversion Response	Duration of CTC conversion response was defined as the time from the date of an initial CTC conversion response to the earlier of CTC conversion progression or death. Participants who had not ended their response at the time of analysis had duration of CTC response censored on the date of their last CTC0 or CTC conversion assessment.	From the date of an initial CTC conversion response to the earlier of CTC conversion progression or death (maximum duration of acapatamab treatment was 98.43 weeks/AMG 404 treatment was 105.14 weeks)
Subprotocols A, B, C (Parts 1, 2 and 3) and D: Duration of PSA Response	Duration of PSA response was defined as the time of an initial PSA response (PSA 50) to the earlier of PSA progression or death. Participants who had not ended their response at the time of analysis had duration of PSA response censored on the date of their last PSA measurement.	From date of an initial PSA response (PSA 50) to the earlier of PSA progression or death (maximum duration of acapatamab treatment was 98.43 weeks/AMG 404 treatment was 105.14 weeks)
Subprotocols A, B, C (Parts 1, 2 and 3) and D: Duration of Response Per RECIST 1.1	Duration of response per RECIST 1.1 was defined as the time from the date of an initial objective response (CR/PR) per RECIST 1.1 to the earlier of soft-tissue progression per RECIST 1.1 or death. CR/PR must have been confirmed at least 4 weeks later. Participants who had not ended their response at the time of analysis had duration of response censored at their last evaluable tumor assessment by computed tomography (CT)/magnetic resonance imaging (MRI) scan.	From date of an initial objective response per RECIST 1.1 to the earlier of soft-tissue progression per RECIST 1.1 or death (maximum duration of acapatamab treatment was 98.43 weeks/AMG 404 treatment was 105.14 weeks)
Subprotocols A, B, C (Parts 1, 2 and 3) and D: Overall Survival (OS)	OS was defined as the time from the date of trial Day 1 until death due to any cause. OS time (months) = (date of death - trial Day 1 + 1) x 12/365.25. Any participant not known to have died at the time of analysis was censored based on the last recorded date on which the participant was alive. The median was estimated using the Kaplan-Meier method and the 95% confidence interval was estimated using the method by Kalbfleisch and Prentice.	From the date of study Day 1 until death due to any cause (maximum duration of acapatamab treatment was 98.43 weeks/AMG 404 treatment was 105.14 weeks)
Subprotocols A, B, C (Parts 1, 2 and 3) and D: Radiographic Progression Free Survival (rPFS)	rPFS was defined as the time from trial Day 1 to radiographic progression. If a participant had no evaluable post-baseline and on-trial disease assessment and was on trial without disease progression (PD) or death recorded, rPFS was censored on the date of the first dose of the investigational product (IP). rPFS was censored at the last evaluable radiographic tumor assessment date for participants who had no PD, death or new anti-cancer therapy reported, started a new anti-cancer therapy prior to PD or death, if death recorded without new anti-cancer therapy and without PD, if death or PD immediately after more than one consecutively missed tumor assessment occurred. The median was estimated using the Kaplan-Meier method and the 95% confidence interval was estimated using the method by Brookmeyer and Crowley.	From trial Day 1 to the earlier of a radiographic progression or death from any cause (maximum duration of acapatamab treatment was 98.43 weeks/AMG 404 treatment was 105.14 weeks)
Subprotocols A, B, C (Parts 1, 2 and 3) and D: PSA PFS	PSA PFS was defined as the interval from trial Day 1 to the earlier of a PSA progression or death from any cause; otherwise, PSA PFS was censored on the date of the last PSA measurement. If a participant had no baseline or post-baseline PSA measurement and a vital status of alive or known, PSA PFS was censored at trial Day 1. The median was estimated using the Kaplan-Meier method and the 95% confidence interval was estimated using the method by Brookmeyer and Crowley.	From trial Day 1 to the earlier of a PSA progression or death from any cause (maximum duration of acapatamab treatment was 98.43 weeks/AMG 404 treatment was 105.14 weeks)
Subprotocols A, B, C (Parts 1, 2 and 3) and D: Clinical PFS	Clinical PFS was defined as the time from the first dose to clinical disease progression or death from any cause. If a participant had no evaluable post-baseline or on-trial disease assessment or was on trial without PD or death recorded, clinical PFS was censored on the date of the first dose of the IP. Otherwise, clinical PFS was censored on the date of last assessment. The median was estimated using the Kaplan-Meier method and the 95% confidence interval was estimated using the method by Brookmeyer and Crowley.	From first dose of acapatamab or AMG 404 (subprotocol C only) to clinical disease progression or death from any cause (maximum duration of acapatamab treatment was 98.43 weeks/AMG 404 treatment was 105.14 weeks)
Subprotocols A, B, C (Parts 1, 2 and 3) and D: Time to Radiographic Progression	Time to radiographic progression was defined as the interval from Day 1 to radiographic progression in the absence of subsequent anticancer therapy. If a participant had no evaluable post-baseline and on-trial disease assessment and was on trial without PD or death recorded, time to radiographic progression was censored on the date of the first dose of the IP. Time to radiographic progression was censored on the date of last evaluable radiographic tumor assessment for participants who: had no PD but death recorded without new anti-cancer therapy;; had no PD, death, or new anti-cancer therapy;; had PD or death immediately after more than one consecutively missed tumor assessment;; started new anti-cancer therapy prior to PD or death, or prior to any other disease assessment if there is no PD or death. The median was estimated using the Kaplan-Meier method and the 95% CI was estimated using the method by Brookmeyer and Crowley.	From trial Day 1 to radiographic progression in the absence of subsequent anticancer therapy (maximum duration of acapatamab treatment was 98.43 weeks/AMG 404 treatment was 105.14 weeks)
Subprotocols A, B, C (Parts 1, 2 and 3) and D: Time to PSA Progression	Time to PSA progression was defined as the interval from trial Day 1 to PSA progression. If a participant had no evaluable post-baseline or on-trial PSA assessment, time to PSA progression was censored on the date of the first dose of the IP. Otherwise, time to PSA progression was censored on the date of the last PSA assessment. The median was estimated using the Kaplan-Meier method and the 95% confidence interval was estimated using the method by Brookmeyer and Crowley.	From trial Day 1 to PSA progression (maximum duration of acapatamab treatment was 98.43 weeks/AMG 404 treatment was 105.14 weeks)
Subprotocols A, B, C (Parts 1, 2 and 3) and D: Time to Subsequent Therapy	Time to subsequent therapy was defined as the interval from trial Day 1 to the time a participant starts/receives the subsequent cancer therapy/subsequent therapy; otherwise, time to subsequent therapy was censored at the last known date of any of the trial assessments prior to initiating the subsequent cancer therapy/subsequent therapy. The median was estimated using the Kaplan-Meier method and the 95% confidence interval was estimated using the method by Brookmeyer and Crowley.	From trial Day 1 to the time a participant starts/receives the subsequent cancer therapy/subsequent therapy (maximum duration of acapatamab treatment was 98.43 weeks/AMG 404 treatment was 105.14 weeks)
Subprotocols A, B, C (Parts 1, 2 and 3) and D: Percentage of Participants Who Experienced a Gallium Prostate-specific Membrane Antigen-11 (PSMA-11) Response	A Gallium PSMA-11 response was defined as a ≥ 50% reduction from baseline in the maximum standardized update value (SUV) using 68Gallium (68Ga)-PSMA-11 positron emission tomography (PET)/CT. PSMA-11 response percentages were based on the number of participants with a baseline PSMA assessment (defined as the last non-missing value on or prior to the pre-dose of acapatamab/AMG 404 assessments) on Cycle 1 Day 1. The 95% confidence interval was calculated based on the Clopper-Pearson method.	Cycle 1 Day 1 to 14 days post-last dose of acapatamab or AMG 404 (maximum duration of acapatamab treatment was 98.43 weeks/AMG 404 treatment was 105.14 weeks)
Subprotocols A, B, C (Parts 1, 2 and 3) and D: Time to Symptomatic Skeletal Events	Time to symptomatic skeletal events was defined as time from trial Day 1 to the first symptomatic skeletal event, otherwise time to symptomatic skeletal event was censored at the last dose of acapatamab/AMG 404 or end of safety follow-up date, whichever was later. Symptomatic skeletal events included fracture, spinal cord compression and radiation or surgery to bone. The median was estimated using the Kaplan-Meier method and the 95% confidence interval was estimated using the method by Brookmeyer and Crowley.	From trial Day 1 to the first symptomatic skeletal event (maximum duration of acapatamab treatment was 98.43 weeks/AMG 404 treatment was 105.14 weeks)
Subprotocols A, B, C (Parts 1, 2 and 3) and D: Total Alkaline Phosphatase Levels	Alkaline phosphatase levels were collected locally and centrally.	Baseline and end of treatment visit (up to 14 days post-last dose of acapatamab/AMG 404. Each cycle was 28 days, maximum duration of acapatamab treatment was 98.43 weeks/AMG 404 treatment was 105.1 weeks).
Subprotocols A, B, C (Parts 1, 2 and 3) and D: Bone Specific Alkaline Phosphatase Levels	Bone specific alkaline phosphatase levels were collected locally and centrally.	Baseline and end of treatment visit (up to 14 days post-last dose of acapatamab/AMG 404. Each cycle was 28 days, maximum duration of acapatamab treatment was 98.43 weeks/AMG 404 treatment was 105.1 weeks).
Subprotocols A, B, C (Parts 1, 2 and 3) and D: Lactate Dehydrogenase Levels	Lactate dehydrogenase levels were collected locally and centrally.	Baseline and end of treatment visit (up to 14 days post-last dose of acapatamab/AMG 404. Each cycle was 28 days, maximum duration of acapatamab treatment was 98.43 weeks/AMG 404 treatment was 105.1 weeks).
Subprotocols A, B, C (Parts 1, 2 and 3) and D: Hemoglobin Levels	Hemoglobin levels were collected locally.	Baseline, safety follow-up visit (up to 30 days post-last dose of acapatamab/AMG 404), safety follow-up 2 (subprotocol C only, up to 5 months post-dose). Each cycle = 28 days, max acapatamab duration = 98.43 weeks, max AMG 404 duration = 105.1 weeks.
Subprotocols A, B, C (Parts 1, 2 and 3) and D: Neutrophil-to-lymphocyte Ratio	Data for the neutrophil-to-lymphocyte ratio were collected locally. Neutrophil-to-lymphocyte ratio was calculated by dividing the number of absolute neutrophils by the number of lymphocytes.	Baseline, safety follow-up visit (up to 30 days post-last dose of acapatamab/AMG 404), safety follow-up 2 (subprotocol C only, up to 5 months post-dose). Each cycle = 28 days, max acapatamab duration = 98.43 weeks, max AMG 404 duration = 105.1 weeks.
Subprotocols A, B, C (Parts 1, 2 and 3) and D: Urine N-telopeptide Levels	Urine N-telopeptide levels were collected centrally.	Baseline and end of treatment visit (up to 14 days post-last dose of acapatamab/AMG 404. Each cycle was 28 days, maximum duration of acapatamab treatment was 98.43 weeks/AMG 404 treatment was 105.1 weeks).
Subprotocol A, B and C (Parts 1 and 2) and D: Maximum Serum Concentration (Cmax) of Acapatamab	Serum concentrations of acapatamab were determined using a validated assay.	Cycle 1: Days 1 to 7 and Cycle 2: Days 1 to 14 (each cycle was 28 days)
Subprotocol A, B and C (Parts 1 and 2) and D: Area Under the Curve Over the Dosing Interval (AUCtau)	Serum concentrations of acapatamab were determined using a validated assay.	Cycle 1: Days 1 to 7 and Cycle 2: Days 1 to 14 (each cycle was 28 days)
Subprotocol A, B and C (Parts 1 and 2) and D: Time to Reach Cmax (Tmax) of Acapatamab	Serum concentrations of acapatamab were determined using a validated assay.	Cycle 1: Days 1 to 7 and Cycle 2: Days 1 to 14 (each cycle was 28 days)
Subprotocol A, B and C (Parts 1 and 2) and D: Terminal Half-life (t1/2z) of Acapatamab	Serum concentrations of acapatamab were determined using a validated assay.	Cycle 2: Days 1 to 14 (each cycle was 28 days)
Subprotocol C, Part 3: Number of Participants Who Experienced TEAEs and Treatment-related AEs	A TEAE was defined as any untoward medical occurrence in a clinical trial participant irrespective of a causal relationship with the trial treatment that started after the first dose of acapatamab. A treatment-related TEAE was defined as a TEAE that had a reasonable possibility of being caused by acapatamab. Clinically significant changes from baseline in vital signs and clinical laboratory tests were also recorded as TEAEs.	From first dose of AMG 404 to the first of 30 days after last dose of acapatamab, end of trial date or the initiation of a new anticancer therapy; median (min, max) duration was 6.14 (0.14, 105.14) weeks

Collaborators and Investigators

• Sponsor: Amgen
• Investigators: Study Director: MD, Amgen

Publications and helpful links

Helpful Links

• AmgenTrials clinical trials website

Study record dates

Study Major Dates

• Study Start (Actual): January 15, 2021
• Primary Completion (Actual): October 23, 2023
• Study Completion (Actual): October 23, 2023

Study Registration Dates

• First Submitted: November 13, 2020
• First Submitted That Met QC Criteria: November 13, 2020
• First Posted (Actual): November 17, 2020

Study Record Updates

• Last Update Posted (Actual): August 26, 2026
• Last Update Submitted That Met QC Criteria: August 4, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: mCRPC; Acapatamab; HALF-LIFE EXTENDED (HLE) BITE; Metastatic Castration-resistant Prostate Cancer; 68; Gallium (68Ga)-prostate-specific membrane; antigen (PSMA)-11 positron emission; tomography(PET)/computed tomography (CT); and; 18; F-fluorodeoxyglucose (FDG) PET/CT; based response evaluation; Bispecific T cell Engager; BITE
• Additional Relevant MeSH Terms: Wounds and Injuries; Chemically-Induced Disorders; Poisoning; Bites and Stings; Antineoplastic Agents, Immunological; Antineoplastic Agents; Physiological Effects of Drugs; Molecular Mechanisms of Pharmacological Action; Hormones, Hormone Substitutes, and Hormone Antagonists; Hormone Antagonists; Androgen Antagonists; Amino Acids, Peptides, and Proteins; Proteins; Pharmacologic Actions; Chemical Actions and Uses; Therapeutic Uses; Enzymes; Enzymes and Coenzymes; Oxidoreductases; Cytochromes; Mixed Function Oxygenases; Oxygenases; Hemeproteins; Immune Checkpoint Inhibitors; Androgen Receptor Antagonists; abiraterone; enzalutamide; Cytochrome P-450 Enzyme System
• Other Study ID Numbers: 20190505; 2020-001305-23 (EudraCT Number)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: De-identified individual patient data for variables necessary to address the specific research question in an approved data sharing request.
• IPD Sharing Time Frame: Data sharing requests relating to this study will be considered beginning 18 months after the study has ended and either 1) the product and indication have been granted marketing authorization in both the US and Europe or 2) clinical development for the product and/or indication discontinues and the data will not be submitted to regulatory authorities. There is no end date for eligibility to submit a data sharing request for this study.
• IPD Sharing Access Criteria: Qualified researchers may submit a request containing the research objectives, the Amgen product(s) and Amgen study/studies in scope, endpoints/outcomes of interest, statistical analysis plan, data requirements, publication plan, and qualifications of the researcher(s). In general, Amgen does not grant external requests for individual patient data for the purpose of re-evaluating safety and efficacy issues already addressed in the product labelling. Requests are reviewed by a committee of internal advisors. If not approved, a Data Sharing Independent Review Panel will arbitrate and make the final decision. Upon approval, information necessary to address the research question will be provided under the terms of a data sharing agreement. This may include anonymized individual patient data and/or available supporting documents, containing fragments of analysis code where provided in analysis specifications. Further details are available at the URL below.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No