Pembrolizumab ( Keytruda ) plus Olaparib ( Lynparza ) has shown antitumor activity and acceptable safety in Docetaxel-pretreated pts with metastatic castration-resistant prostate cancer ( mCRPC ) enrolled in cohort A of the phase I/2 KEYNOTE-365 study.
Updated results including time to symptomatic skeletal event, radiographic bone progression, and radiographic soft tissue progression are reported.
Patients with Docetaxel-pretreated metastatic castration-resistant prostate cancer with disease progression within 6 months of screening received Pembrolizumab 200 mg IV Q3W + Olaparib 400-mg capsule or 300-mg tablet orally twice daily.
Patients could have received 1 other chemotherapy and 2 or less second-generation androgen receptor–targeted therapies.
Primary endpoints were: prostate specific antigen ( PSA ) response rate ( decrease 50% or more from baseline ), objective response rate ( ORR ) per RECIST v1.1 by blinded independent central review, and safety.
Secondary end points: disease control rate ( DCR ), composite response rate, duration of response ( DOR ), radiographic progression-free survival ( rPFS ) per PCWG-modified RECIST, overall survival ( OS ), time to symptomatic skeletal event, radiographic bone progression, and radiographic soft tissue progression.
84 of 87 enrolled patients were treated; 48 of 84 ( 57.1% ) had measurable disease. Median ( range ) time from enrollment to data cutoff was 3.6 ( 0.0-29.2 ) months for all patients and 26.7 ( 21.2-29.2 ) months for 41 patients with 27 or more weeks follow-up.
Confirmed PSA response rate in 82 patients with PSA at baseline was 9%.
Confirmed ORR in patients with measurable disease and 27 or more weeks potential follow-up ( n = 24 ) was 8% ( 2 PRs ).
Median rPFS was 4.3 months ( 95% CI, 3.4-7.7 ) and median OS was 14.4 months ( 95% CI, 8.1-18.5 ).
At 12 mo, rPFS rate was 23.3% and OS rate was 58.2% by Kaplan-Meier.
Grade 3 or more treatment-related adverse events ( TRAEs ) occurred in 29 patients ( 35% ); 2 patients died of TRAEs ( 1 myocardial infarction, 1 unknown ).
In conclusion, Pembrolizumab + Olaparib continued to show activity and acceptable safety in patients with Docetaxel-pretreated mCRPC. ( Xagena )
Source: European Society for Medical Oncology ( ESMO ) Virtual Meeting, 2020