Phase 1/2 Trial for GDC‑1261 in Advanced Prostate Cancer

GDC‑1261 is a new study drug being tested in men with advanced or metastatic prostate cancer in a first‑in‑human Phase 1/2 trial. The public description of the study states that the main goals are to evaluate the safety profile, pharmacokinetics, and preliminary anti‑tumor activity of GDC‑1261 and to identify a recommended dose and dosing schedule for later‑phase trials. At this stage, the development is entirely early‑phase and exploratory, with no efficacy results posted and no peer‑reviewed clinical data available.

The trial is designed as an interventional Phase 1/2 dose‑escalation and expansion study with a sequential assignment model and open‑label treatment, meaning all enrolled participants receive GDC‑1261 at a dose defined by the study protocol. The estimated enrollment is around 260 participants, which is relatively large for a first‑in‑human oncology trial and reflects an intention to move rapidly from initial safety and pharmacokinetic work into broader expansion cohorts once a tolerable dose range has been defined.

The target population is adult males with histologically or cytologically confirmed prostate adenocarcinoma and radiologically documented metastatic disease. Participants must have experienced disease progression during or after their most recent line of systemic therapy, positioning GDC‑1261 in a setting where standard options have already been used and the disease has continued to advance. Eligibility also requires an Eastern Cooperative Oncology Group performance status of 0 or 1, a life expectancy of at least three months, and adequate function of major organs such as liver, kidney, and bone marrow, which is standard for early‑phase oncology trials.

Despite this detailed clinical framework, almost nothing public is known about the molecule itself beyond its name and indication. Neither the main trial registry entry nor secondary listings provide information about the molecular target, signaling pathway, or chemical class of GDC‑1261, and there are currently no linked preclinical abstracts or mechanism‑of‑action summaries.

Clinical trial.