MCRPC: add-on custirsen fails phase 3 AFFINITY trial

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  • Custirsen fails to boost survival in patients with metastatic castration-resistant prostate cancer (mCRPC) whose disease has progressed after treatment with docetaxel.

Why this matters

  • Custirsen blocks protein clusterin, which is associated with treatment resistance. 
  • Post hoc analysis of the SYNERGY trial reported survival benefits with first-line docetaxel plus custirsen.

Study design

  • Phase 3 AFFINITY study of 635 patients with mCRPC randomly assigned to receive either cabazitaxel plus prednisone plus custirsen (n=317) or cabazitaxel plus prednisone (control group, n=318).
  • Funding: OncoGenex Pharmaceuticals.

Key results

  • Overall OS did not differ between the 2 groups (P=.53).
  • In patients with poor prognosis, OS was similar in both the groups (P=.80).
  • 76% of patients in the custirsen group vs 66% in the control group experienced grade ≥3 adverse events; most common were neutropenia (22% vs 20%), anemia (22% vs 16%), and fatigue (7% vs 6%).


  • Open-label study.