CONTRADICTING EVIDENCE: In this Phase I study (NCT02215096), patients with PTEN-deficient mCRPC...the 12-week non-PD rate was 50% (95% CI: 28.2-71.8%, n=22); 1 (3%) patient achieved a radiographic partial response lasting 36 weeks. 4/34 (12%) patients had prostate-specific antigen reduction of {greater than or equal to}50%.... GSK2636771 plus enzalutamide in patients with PTEN-deficient mCRPC after failing enzalutamide, limited antitumor activity was observed.