Capivasertib + Abiraterone in CAPItello-281: Promising rPFS in PTEN-Deficient mHSPC

The phase 3 trial CAPItello-281, has delivered compelling evidence that capivasertib combined with abiraterone could transform treatment for PTEN-deficient metastatic hormone-sensitive prostate cancer (mHSPC), a subtype affecting a substantial portion of advanced cases. In this double-blind study, 1012 patients with PTEN deficiency (defined rigorously as 90% or more viable malignant cells showing no cytoplasmic staining via immunohistochemistry) were randomized 1:1 to receive either capivasertib (400 mg twice daily, 4 days on/3 days off) plus abiraterone (1000 mg daily) and androgen deprivation therapy (ADT), or placebo plus the same abiraterone/ADT backbone.

The primary endpoint, radiographic progression-free survival (rPFS), favored the investigational arm with a median of 33.2 months  versus 25.7 months for placebo, marking a clinically meaningful 7.5-month delay in progression. Secondary outcomes like overall survival (HR 0.90 at interim analysis), time to subsequent therapy, skeletal event-free survival, and pain progression further supported the regimen’s profile, with consistent benefits even at stricter PTEN loss cutoffs (≥95% or 100%). What sets these results apart, however, is the emphasis on patient-reported outcomes (PROs), assessed via tools like the Functional Assessment of Cancer Therapy – Prostate (FACT-P) and Patient Global Impression of Severity (PGI-S). Despite higher adverse events in the capivasertib group (98.8% vs 92.0%), quality of life held steady: FACT-P physical wellbeing showed an LS mean difference of –0.4 (95% CI, –0.89 to 0.14), functional wellbeing –0.3 (95% CI, –1.01 to 0.37), and total score +0.4 (95% CI, –1.97 to 2.78).

The addition of capivasertib preserved functional aspects of daily life—work, sleep, enjoyment—while enabling ~80% of patients to continue treatment without QoL erosion, positioning it as a potential first-in-class targeted option for PTEN-deficient mHSPC. For prostate cancer warriors, this builds directly on preclinical synergies like fadraciclib + capivasertib (or ipatasertib),  for dual CDK9/AKT pathway attacks in PTEN-loss models.

Source.