Poveda, Andrés

Background Poly(adenosine diphosphate ribose) polymerase (PARP) inhibitors exhibit promising activity against ovarian cancers, but their efficacy can be limited by acquired drug resistance. This study explores the role of autophagy in regulating the sensitivity of ovarian cancer cells to PARP inhibitors. Methods Induction of autophagy was detected by punctate LC3 fluorescence staining, LC3I to LC3II conversion on Western blot analysis, and electron microscopy. Enhanced growth inhibition and apoptosis were observed when PARP inhibitors were used with hydroxychloroquine, chloroquine (CQ), or LYS05 to block the hydrolysis of proteins and lipids in autophagosomes or with small interfering RNA against ATG5 or ATG7 to prevent the formation of autophagosomes. The preclinical efficacy of the combination of CQ and olaparib was evaluated with a patient‐derived xenograft (PDX) and the OVCAR8 human ovarian cancer cell line. Results Four PARP inhibitors (olaparib, niraparib, rucaparib, and talazoparib) induced autophagy in a panel of ovarian cancer cells. Inhibition of autophagy with CQ enhanced the sensitivity of ovarian cancer cells to PARP inhibitors. In vivo, olaparib and CQ produced additive growth inhibition in OVCAR8 xenografts and a PDX. Olaparib inhibited PARP activity, and this led to increased reactive oxygen species (ROS) and an accumulation of γ‐H2AX. Inhibition of autophagy also increased ROS and γ‐H2AX and enhanced the effect of olaparib on both entities. Treatment with olaparib increased phosphorylation of ATM and PTEN while decreasing the phosphorylation of AKT and mTOR and inducing autophagy. Conclusions PARP inhibitor–induced autophagy provides an adaptive mechanism of resistance to PARP inhibitors in cancer cells with wild‐type BRCA, and a combination of PARP inhibitors with CQ or other autophagy inhibitors could improve outcomes for patients with ovarian cancer.

Abstract Purpose: In the randomized phase III trial, Gynecologic Oncology Group (GOG) protocol 240, the incorporation of bevacizumab with chemotherapy significantly increased overall survival (OS) in women with advanced cervical cancer. A major objective of GOG-240 was to prospectively analyze previously identified pooled clinical prognostic factors known as the Moore criteria. Experimental Design: Potential negative factors included black race, performance status 1, pelvic disease, prior cisplatin, and progression-free interval <365 days. Risk categories included low-risk (0–1 factor), mid-risk (2–3 factors), and high-risk (4–5 factors). Each test of association was conducted at the 5% level of significance. Logistic regression and survival analysis was used to determine whether factors were prognostic or could be used to guide therapy. Results: For the entire population (n = 452), high-risk patients had significantly worse OS (P < 0.0001). The HRs of death for treating with topotecan in low-risk, mid-risk, and high-risk subsets are 1.18 [95% confidence interval (CI), 0.63–2.24], 1.11 (95% CI, 0.82–1.5), and 0.84 (95% CI, 0.50–1.42), respectively. The HRs of death for treating with bevacizumab in low-risk, mid-risk, and high-risk subsets are 0.96 (95% CI, 0.51–1.83; P = 0.9087), 0.673 (95% CI, 0.5–0.91; P = 0.0094), and 0.536 (95% CI, 0.32–0.905; P = 0.0196), respectively. Conclusions: This is the first prospectively validated scoring system in cervical cancer. The Moore criteria have real-world clinical applicability. Toxicity concerns may justify omission of bevacizumab in some low-risk patients where survival benefit is small. The benefit to receiving bevacizumab appears to be greatest in the moderate- and high-risk subgroups (5.8-month increase in median OS). Clin Cancer Res; 21(24); 5480–7. ©2015 AACR.