New data from the Phase 1b trial of ORIC-944, in combination with androgen receptor (AR) inhibitors (Apalutamide or Darolutamide) for the treatment of metastatic castration-resistant prostate cancer (mCRPC), was recently presented.
The trial demonstrated broad and deep prostate-specific antigen (PSA) responses across all dose levels of ORIC-944 combined with the two AR inhibitors.

Key efficacy outcomes include:

• A 59% PSA50 response rate (patients achieving ≥50% reduction in PSA), with 47% confirmed responses and one additional response pending confirmation.
• A 24% PSA90 response rate (≥90% reduction in PSA), all confirmed.

Responses were durable, with multiple patients ongoing on treatment for nearly a year or longer.

These results suggest substantial clinical activity and position ORIC-944 as a potentially best-in-class PRC2 inhibitor for patients with mCRPC who have progressed on prior AR pathway therapies.

The combination regimens were generally well tolerated, with the vast majority of adverse events being Grade 1 or 2, primarily mild to moderate gastrointestinal events such as diarrhea (reported in 53% of patients, mostly low grade). Only one Grade 3 event was observed, and no Grade 4 or 5 treatment-related adverse events occurred. This safety profile supports the potential for long-term dosing.

Source.

Clinical trial.