Pharmacokinetic Effects and Safety of Olaparib Administered with Endocrine Therapy: A Phase I Study in Patients with Advanced Solid Tumours.

Advances in therapy, Nov 2018

Plummer R, Verheul HM, De Vos FYFL, Leunen K, Molife LR, Rolfo C, Grundtvig-Sørensen P, De Grève J, Rottey S, Jerusalem G, Italiano A, Spicer J, Dirix L, Goessl C, Birkett J, Spencer S, Learoyd M, Bailey C, Dean E.

doi: 10.1007/s12325-018-0804-z

 https://www.ncbi.nlm.nih.gov/pubmed/?term=10.1007%2Fs12325-018-0804-z

Abstract

INTRODUCTION :

The PARP inhibitor olaparib is efficacious as monotherapy and has potential application in combination with endocrine therapy for the treatment of breast cancer. This phase I study assessed the safety and pharmacokinetic (PK) profiles of olaparib combined with tamoxifen, anastrozole or letrozole in patients with advanced solid tumours.

METHODS :

During part A, PK profiles were assessed in three consecutive treatment periods: (1) olaparib (tablet) 300 mg bid, days 1-5 followed by a 4-day washout; (2) cohort 1, tamoxifen 60 mg loading dose qd days 10-13, 20 mg qd days 14-26; cohort 2, anastrozole 1 mg qd days 10-19; cohort 3, letrozole 2.5 mg qd days 10-38; (3) as for period 2, with concomitant olaparib 300 mg bid for 5 days. Patients could then enter part B and receive olaparib monotherapy (300 mg bid continuously). Safety was assessed in parts A and B until 12 months after the last patient entered part B.

RESULTS :

Seventy-nine patients (20.3% with breast cancer) received treatment in part A; 72 completed part A and 69 entered part B. Anastrozole and letrozole had no effect on the PK profile of olaparib and vice versa. Co-administration with tamoxifen produced a modest decrease in exposure to olaparib [geometric least-squares mean (GLSmean) Cmax,ss and AUC0-τ decreased by 20% (90% CI 0.71-0.90) and 27% (0.63-0.84), respectively]. Exposure to tamoxifen was slightly increased when combined with olaparib [GLSmean Cmax,ss and AUC0-τincreased by 13% (1.06-1.22) and 16% (1.11-1.21), respectively]; however, the 90% CI fell within the 0.7-1.43 boundary and there were no changes in exposure to tamoxifen metabolites. The safety profile for olaparib alone and in combination with the antihormonal therapies was acceptable.

CONCLUSIONS :

The combination of olaparib and either anastrozole, letrozole or tamoxifen was generally well tolerated, with no clinically relevant PK interactions identified.

FUNDING :

AstraZeneca.