No abstract

AstraZeneca.

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.

AstraZeneca.

Background Olaparib (Lynparza™) is a PARP inhibitor approved for advanced BRCA -mutated ( BRCA m) ovarian cancer. PARP inhibitors may benefit patients whose tumours are dysfunctional in DNA repair mechanisms unrelated to BRCA1/2 . We report exploratory analyses, including the long-term outcome of candidate biomarkers of sensitivity to olaparib in BRCA wild-type ( BRCA wt) tumours. Methods Tumour samples from an olaparib maintenance monotherapy trial (Study 19, D0810C00019; NCT00753545) were analysed. Analyses included classification of mutations in genes involved in homologous recombination repair (HRR), BRCA1 promoter methylation status, measurement of BRCA1 protein and Myriad HRD score. Results Patients with BRCA m tumours gained most benefit from olaparib; a similar treatment benefit was also observed in 21/95 patients whose tumours were BRCA wt but had loss-of-function HRR mutations compared to patients with no detectable HRR mutations (58/95). A higher median Myriad MyChoice ® HRD score was observed in BRCA m and BRCA wt tumours with BRCA1 methylation. Patients without BRCA m tumours derived benefit from olaparib treatment vs placebo although to a lesser extent than BRCA m patients. Conclusions Ovarian cancer patients with tumours harbouring loss-of-function mutations in HRR genes other than BRCA1 / 2 may constitute a small, molecularly identifiable and clinically relevant population who derive treatment benefit from olaparib similar to patients with BRCA m.

Olaparib/paclitaxel is active in the treatment of patients with metastatic gastric cancer, with a greater OS benefit in ATMlow patients. A phase III trial in this setting is under way.

No abstract

Maintenance therapy with olaparib has improved progression-free survival in women with high-grade serous ovarian cancer (HGSOC), particularly those harboring mutations. The objective of this study was to characterize long-term (LT) versus short-term (ST) responders to olaparib. A comparative molecular analysis of Study 19 (NCT00753545), a randomized phase II trial assessing olaparib maintenance after response to platinum-based chemotherapy in HGSOC, was conducted. LT response was defined as response to olaparib/placebo >2 years, ST as <3 months. Molecular analyses included germline status, three-biomarker homologous recombination deficiency (HRD) score, methylation, and mutational profiling. Another olaparib maintenance study (Study 41; NCT01081951) was used as an additional cohort. Thirty-seven LT (32 olaparib) and 61 ST (21 olaparib) patients were identified. Treatment was significantly associated with outcome ( < 0.0001), with more LT patients on olaparib (60.4%) than placebo (11.1%). LT sensitivity to olaparib correlated with complete response to chemotherapy ( < 0.05). In the olaparib LT group, 244 genetic alterations were detected, with , and mutations being most common (90%, 25%, and 35%, respectively). mutations were enriched among the LT responders. methylation was not associated with response duration. High myriad HRD score (>42) and/or mutation was associated with LT response to olaparib. Study 41 confirmed the correlation of LT response with olaparib and mutation. Findings show that LT response to olaparib may be multifactorial and related to homologous recombination repair deficiency, particularly defects. The type of mutation warrants further investigation. .