A Study Evaluating the Safety, Pharmacokinetics, and Preliminary Activity of GDC-1261 in Participants With Advanced or Metastatic Prostate Cancer

A Phase I/II Dose-escalation and Expansion Study Evaluating the Safety, Pharmacokinetics, and Preliminary Activity of GDC-1261 in Patients With Advanced or Metastatic Prostate Cancer

The purpose of this study is to evaluate the safety, pharmacokinetics (PK), and preliminary activity of GDC-1261 in participants with advanced or metastatic prostate cancer. It's also to identify a recommended dose(s) and regimen for GDC-1261 for subsequent studies.

Study Overview

• Status: Not yet recruiting
• Conditions: Metastatic Prostate Cancer; Advanced Prostate Cancer
• Intervention / Treatment: Drug: GDC-1261

• Study Type: Interventional
• Enrollment (Estimated): 260
• Phase: Phase 2; Phase 1

Contacts and Locations

• Study Contact: Name: Reference Study ID Number: GO46445 https://forpatients.roche.com/; Phone Number: 888-662-6728; Email: global-roche-genentech-trials@gene.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Eastern Cooperative Oncology Group (ECOG) Performance Status of <=1
• Life expectancy is >= 3 months
• Histologically or cytologically confirmed prostate adenocarcinoma
• Disease progression during or following the direct prior line of therapy
• Ongoing androgen deprivation therapy (ADT) with gonadotropin-releasing hormone (GnRH) agonist or antagonist, or have had bilateral orchiectomy
• Metastatic disease
• Adequate end organ function

Exclusion Criteria:

• Treatment with any approved systemic anti-cancer therapy within 14 days or 5 drug elimination half-lives
• Structurally unstable bone lesions suggest an impending fracture
• Untreated central nervous system (CNS) metastases or leptomeningeal disease
• Uncontrolled pain
• History of malignancy within 5 years
• Infection requiring systemic IV antibiotics within 14 days or oral antibiotics within 7 days prior to screening, or any evidence of current infection
• Any medical condition or abnormal clinical laboratory finding that, in the investigator's judgment, would preclude the individual's safe participation in and completion of the study or could affect the interpretation of the results

Study Plan

How is the study designed?

Design Details

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

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Dose Escalation + Expansion; Participants will receive GDC-1261 as per the schedule described in the protocol.	Drug: GDC-1261; Participants will receive GDC-1261 as per the schedule described in the protocol.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Percentage of Participants With Adverse Events (AEs)	Up to approximately 24 months
Incidence and Nature of DLTs Dose-limiting Toxicities (DLTs)	From Day 1-28 of Cycle 1 (1 Cycle = 28 days)

Secondary Outcome Measures

Outcome Measure	Time Frame
Plasma Concentration of GDC-1261	Up to approximately 24 months
Plasma Concentration of GDC-1261 Either in Fasted or Fed State	Up to approximately 24 months
Prostate-Specific Antigen-30% (PSA30) Response Rate	Up to approximately 24 months
PSA50 Response Rate	Up to approximately 24 months
PSA90 Response Rate	Up to approximately 24 months
Objective Response Rate (ORR)	Up to approximately 24 months
Recommended Dose of GDC-1261	Up to approximately 24 months

Collaborators and Investigators

• Sponsor: Genentech, Inc.
• Investigators: Study Director: Clinical Trials, Genentech, Inc.

Study record dates

Study Major Dates

• Study Start (Estimated): April 30, 2026
• Primary Completion (Estimated): November 30, 2027
• Study Completion (Estimated): December 30, 2027

Study Registration Dates

• First Submitted: April 13, 2026
• First Submitted That Met QC Criteria: April 28, 2026
• First Posted (Actual): May 5, 2026

Study Record Updates

• Last Update Posted (Actual): May 5, 2026
• Last Update Submitted That Met QC Criteria: April 28, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Urogenital Diseases; Genital Diseases; Genital Neoplasms, Male; Urogenital Neoplasms; Neoplasms by Site; Neoplasms; Genital Diseases, Male; Prostatic Diseases; Male Urogenital Diseases; Prostatic Neoplasms
• Other Study ID Numbers: GO46445

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: For eligible studies, qualified researchers may request access to individual patient level clinical data. See Roche's commitment to transparency of clinical study information here: https://go.roche.com/data_sharing

Drug and device information, study documents

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