Among patients with HER2-negative metastatic breast cancer and a germline BRCA mutation, olaparib monotherapy provided a significant benefit over standard therapy; median progression-free survival was 2.8 months longer and the risk of disease progression or death was 42% lower with olaparib monotherapy than with standard therapy. (Funded by AstraZeneca; OlympiAD ClinicalTrials.gov number, NCT02000622 .).

Background In the OlympiAD study, olaparib was shown to improve progression-free survival compared with chemotherapy treatment of physician’s choice (TPC) in patients with a germline BRCA1 and/or BRCA2 mutation (BRCAm) and human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer (mBC). We now report the planned final overall survival (OS) results, and describe the most common adverse events (AEs) to better understand olaparib tolerability in this population. Patients and methods OlympiAD, a Phase III, randomized, controlled, open-label study (NCT02000622), enrolled patients with a germline BRCAm and HER2-negative mBC who had received ≤2 lines of chemotherapy for mBC. Patients were randomized to olaparib tablets (300 mg bid) or predeclared TPC (capecitabine, vinorelbine, or eribulin). OS and safety were secondary end points. Results A total of 205 patients were randomized to olaparib and 97 to TPC. At 64% data maturity, median OS was 19.3 months with olaparib versus 17.1 months with TPC (HR 0.90, 95% CI 0.66–1.23; P = 0.513); median follow-up was 25.3 and 26.3 months, respectively. HR for OS with olaparib versus TPC in prespecified subgroups were: prior chemotherapy for mBC [no (first-line setting): 0.51, 95% CI 0.29–0.90; yes (second/third-line): 1.13, 0.79–1.64]; receptor status (triple negative: 0.93, 0.62–1.43; hormone receptor positive: 0.86, 0.55–1.36); prior platinum (yes: 0.83, 0.49–1.45; no: 0.91, 0.64–1.33). Adverse events during olaparib treatment were generally low grade and manageable by supportive treatment or dose modification. There was a low rate of treatment discontinuation (4.9%), and the risk of developing anemia did not increase with extended olaparib exposure. Conclusions While there was no statistically significant improvement in OS with olaparib compared to TPC, there was the possibility of meaningful OS benefit among patients who had not received chemotherapy for metastatic disease. Olaparib was generally well-tolerated, with no evidence of cumulative toxicity during extended exposure.

Selumetinib (AZD6244, ARRY-142886) is a selective, non–ATP-competitive inhibitor of mitogen-activated protein/extracellular signal–regulated kinase kinase (MEK)-1/2. The range of antitumor activity seen preclinically and in patients highlights the importance of identifying determinants of response to this drug. In large tumor cell panels of diverse lineage, we show that MEK inhibitor response does not have an absolute correlation with mutational or phospho-protein markers of BRAF/MEK, RAS, or phosphoinositide 3-kinase (PI3K) activity. We aimed to enhance predictivity by measuring pathway output through coregulated gene networks displaying differential mRNA expression exclusive to resistant cell subsets and correlated to mutational or dynamic pathway activity. We discovered an 18-gene signature enabling measurement of MEK functional output independent of tumor genotype. Where the MEK pathway is activated but the cells remain resistant to selumetinib, we identified a 13-gene signature that implicates the existence of compensatory signaling from RAS effectors other than PI3K. The ability of these signatures to stratify samples according to functional activation of MEK and/or selumetinib sensitivity was shown in multiple independent melanoma, colon, breast, and lung tumor cell lines and in xenograft models. Furthermore, we were able to measure these signatures in fixed archival melanoma tumor samples using a single RT-qPCR–based test and found intergene correlations and associations with genetic markers of pathway activity to be preserved. These signatures offer useful tools for the study of MEK biology and clinical application of MEK inhibitors, and the novel approaches taken may benefit other targeted therapies.