A Phase 3 Randomized Study to Evaluate the Safety and Efficacy of risvutatug rezetecan, a B7-H3 Antibody Drug Conjugate (ADC) in Participants with Metastatic Castration resistant Prostate Cancer (EMBOLD Prostate-302)
A Study of risvutatug rezetecan in Participants with Metastatic Castration resistant Prostate Cancer (mCRPC)
Ishibashi Hideyasu
GlaxoSmithKline K.K.
Akasaka Intercity AIR, 1-8-1 Akasaka, Minato-ku, Tokyo, Japan
+81-120-561-007
jp.gskjrct@gsk.com
Ishibashi Hideyasu
GlaxoSmithKline K.K.
Akasaka Intercity AIR, 1-8-1 Akasaka, Minato-ku, Tokyo, Japan
+81-120-561-007
jp.gskjrct@gsk.com
Pending
Sept. 22, 2026
684
Interventional
randomized controlled trial
open(masking not used)
active control
parallel assignment
treatment purpose
- Participants >-18 years of age
- Has histologically or cytologically confirmed adenocarcinoma of the prostate.
- Has an Eastern Cooperative Oncology Group (ECOG) PS of 0 or 1, with no deterioration in the 2 weeks before randomization.
- Has a life expectancy of at least 4 months.
- Has adequate organ function
- Pathological finding consistent with small cell, neuroendocrine carcinoma of the prostate, mixed histologies or any histology different from adenocarcinoma.
- Participants with known mismatch repair deficient (dMMR)/MSI-H/TMB-H status and eligible for immune checkpoint inhibitor therapy,
- Has a malignancy (except disease under study) that has progressed or required active treatment within the past 24 months except for basal cell or squamous cell carcinomas of the skin or in-situ carcinomas [e.g., breast, cervix] with no evidence of metastatic disease.
- Has undergone major surgery, including local prostate intervention (except prostate biopsy), within 28 days before the date of randomization,
- Has clinically significant bleeding symptoms or significant bleeding tendency within 1 month prior to the first dose.
- Known active infectious diseases requiring systemic treatment or known human immunodeficiency virus (HIV)
- Has untreated brain or central nervous system (CNS) metastases or brain/CNS metastases that have progressed
- Has received systemic immunosuppressive agents within 30 days prior to first dose of study intervention (or requires long-term administration [30 days or longer]).
- Has received any prior therapy with an ADC with a topoisomerase 1 inhibitor (TOPO1-inhibitor) payload
18age old over
No limit
Male
Prostate Cancer
Experimental arm: Participants will receive Risvutatug rezetecan (Ris-Rez).
Active Comparator arm: Participants will receive physician's choice of best supportive/standard of care (BSC), with or without androgen receptor pathway inhibitors (ARPI) Enzalutamide, Abiraterone (with Prednisone or Prednisolone).
1. Radiographic Progression-Free Survival (rPFS) per PCWG3 by BICR: rPFS is defined as time from randomization to the first documented radiographic disease progression, per Prostate cancer clinical trials working group 3 (PCWG3) as assessed by Blinded Independent Central Review (BICR) or death due to any cause, whichever occurs first.
2. Overall Survival (OS): OS is defined as the time from randomization to date of death by any cause.
1. Time to Pain Progression (TTPP).
2. rPFS by Investigator assessment: rPFS is defined as time from randomization to the first documented radiographic disease progression per PCWG3 as assessed by Investigator or death due to any cause, whichever occurs first.
3. Confirmed Objective Response Rate (cORR): cORR is defined as the percentage of participants with a confirmed Complete Response (CR) or Partial Response (PR) per PCWG3 by BICR.
4. Duration of Response (DoR): DoR defined as the time from the date of first confirmed response (CR or PR) to the date of first documented PD per PCWG3 as assessed by BICR or death due to any cause, whichever comes first.
5. Time to Prostate-specific antigen (PSA) progression: Time to PSA progression is defined as the time from randomization to PSA progression according to PCWG3 criteria.
6. Prostate-specific antigen 50 (PSA50) response: PSA50 is defined as the proportion of participants having a >-50% post-baseline PSA reduction from baseline with a consecutive confirmation assessment at least 3 weeks later.
7. Time to first Symptomatic Skeletal-Related Event (SSRE): Time to first SSRE is defined as the time from randomization to first occurrence of any of the following symptomatic skeletal-related events: Use of EBRT to prevent or relieve skeletal symptoms; New symptomatic pathological bone fracture (vertebral or non-vertebral); New symptomatic spinal cord compression; Tumor-related orthopedic surgical intervention.
8. Number of participants with adverse event (AEs), serious adverse event (SAEs), Adverse event of special interest (AESIs) by severity.
9. Number of participants with AEs leading to dose modifications or study intervention discontinuation.
10. Serum concentration of Ris-Rez (conjugated antibody and payload).
11. Number of participants with Antidrug antibody (ADA) and Neutralizing Antibody (NAb) against Ris-Rez.
12. Titers of ADA against Ris-Rez.
13. Participant-reported experience on study treatment: Number of participants who reported their experience with study treatment using validated questionnaires will be measured.
GlaxoSmithKline K.K.
Tottori University Hospital Institutional Review Board
