Journal Article

Oral poly(ADP-ribose) polymerase inhibitor olaparib in patients with BRCA1 or BRCA2 mutations and advanced breast cancer: a proof-of-concept trial

Wickens, Mark, Domchek, Susan M, Mitchell, Gillian, Earl, Helena, Arun, Banu, Carmichael, James, Wardley, Andrew, Loman, Niklas, Schmutzler, Rita K, Weitzel, Jeffrey N, Garber, Judy E, Robson, Mark, Friedlander, Michael, Tutt, Andrew, Audeh, M William

2010

Overview

Olaparib, a novel, orally active poly(ADP-ribose) polymerase (PARP) inhibitor, induced synthetic lethality in BRCA-deficient cells. A maximum tolerated dose and initial signal of efficacy in BRCA-deficient ovarian cancers have been reported. We therefore assessed the efficacy, safety, and tolerability of olaparib alone in women with BRCA1 or BRCA2 mutations and advanced breast cancer. Women (aged ≥18 years) with confirmed BRCA1 or BRCA2 mutations and recurrent, advanced breast cancer were assigned to two sequential cohorts in a phase 2 study undertaken in 16 centres in Australia, Germany, Spain, Sweden, the UK, and the USA. The first cohort (n=27) was given continuous oral olaparib at the maximum tolerated dose (400 mg twice daily), and the second (n=27) was given a lower dose (100 mg twice daily). The primary efficacy endpoint was objective response rate (ORR). This study is registered with ClinicalTrials.gov, number NCT00494234. Patients had been given a median of three previous chemotherapy regimens (range 1–5 in cohort 1, and 2–4 in cohort 2). ORR was 11 (41%) of 27 patients (95% CI 25–59) in the cohort assigned to 400 mg twice daily, and six (22%) of 27 (11–41) in the cohort assigned to 100 mg twice daily. Toxicities were mainly at low grades. The most frequent causally related adverse events in the cohort given 400 mg twice daily were fatigue (grade 1 or 2, 11 [41%]; grade 3 or 4, four [15%]), nausea (grade 1 or 2, 11 [41%]; grade 3 or 4, four [15%]), vomiting (grade 1 or 2, three [11%]; grade 3 or 4, three [11%]), and anaemia (grade 1 or 2, one [4%]; grade 3 or 4, three [11%]). The most frequent causally related adverse events in the cohort given 100 mg twice daily were nausea (grade 1 or 2, 11 [41%]; none grade 3 or 4) and fatigue (grade 1 or 2, seven [26%]; grade 3 or 4, one [4%]). The results of this study provide positive proof of concept for PARP inhibition in BRCA-deficient breast cancers and shows a favourable therapeutic index for a novel targeted treatment strategy in patients with tumours that have genetic loss of function of BRCA1-associated or BRCA2-associated DNA repair. Toxicity in women with BRCA1 and BRCA2 mutations was similar to that reported previously in those without such mutations. AstraZeneca.

• Publisher: Elsevier Ltd,Elsevier,Elsevier Limited
• Subject: Adenosine diphosphate / Adult / Aged / Anemia / Antineoplastic Agents - therapeutic use / Biological and medical sciences / Breast cancer / Breast Neoplasms - drug therapy / Breast Neoplasms - genetics / Breast Neoplasms - pathology / Cancer and Oncology / Cancer och onkologi / Clinical Medicine / Fatigue / Female / General aspects / Genes, BRCA1 / Genes, BRCA2 / Germ-Line Mutation / Gynecology. Andrology. Obstetrics / Humans / Internal Medicine / Klinisk medicin / Mammary gland diseases / Maximum Tolerated Dose / Medical and Health Sciences / Medical research / Medical sciences / Medicin och hälsovetenskap / Middle Aged / Mutation / Ovarian cancer / Phthalazines - therapeutic use / Piperazines - therapeutic use / Poly(ADP-ribose) Polymerase Inhibitors / Prospective Studies / Tumors