Abiraterone acetate (AA) plus prednisone (P) 5 mg QD in metastatic castration-naïve prostate cancer (mCNPC): Detailed safety analyses from the LATITUDE phase 3 trial.

Abstract

182 Background: AA + P added to androgen deprivation therapy (ADT) improves overall survival (OS) in newly diagnosed mCNPC patients (pts). AA has been previously coadministered with P (10 mg QD). As a lower dose of P (5 mg QD) was used in LATITUDE, we conducted additional safety analyses. Methods: 1199 pts with newly diagnosed, high-risk mCNPC (≥ 2 of 3 risk factors: Gleason ≥ 8, ≥ 3 bone lesions, visceral metastases) were randomized 1:1 to AA (1 gm QD) + P (5 mg QD) + ADT or placebos (PBOs) of AA and P + ADT: median treatment duration 24 and 14 mo, respectively. Safety analyses focused on key mineralocorticoid excess (ME)-related adverse events (AEs): hypertension (HTN) and hypokalemia. Results: Increased HTN with 5 mg/d P with AA + ADT (relative risk, 1.6 [95% CI, 1.4-1.9]) was similar to prior studies using 10 mg/d P (COU-AA-301: 1.4 [0.9-2.0]; COU-AA-302: 1.6 [1.2-2.1]). Of Gr 3/4 HTN events, 87% (109/126 [AA + P + ADT]) and 83% (52/63 [PBOs + ADT]) resolved to Gr ≤ 2. There were few cerebrovascular events: AA + P + ADT, 5; PBOs + ADT, 9. The protocol allowed increasing dose of P to 10 mg for ME-related AEs, but most Gr 3/4 HTN events were managed only by supplemental antihypertensives. Prior use of antihypertensives at study entry was predictive of Gr 3/4 HTN in both treatment arms (RR: 1.85; 95% CI, 1.14-3.01). Gr 3/4 hypokalemia increased with AA + P + ADT (10.4% [62/597]) vs PBOs + ADT (1.3% [8/602]); 89% (55/62) and 100% (8/8) of these events improved to Gr ≤ 2. Less than 1% of pts in either arm discontinued therapy for ME-related AEs. Conclusions: In-depth analysis of LATITUDE data confirms the safety of 5 mg/d P with AA + ADT and helps provide practical treatment guidance for managing mCNPC. Clinical trial information: NCT01715285. [Table: see text]