Tumor burden is a potential marker of PARP inhibitor effects in ovarian cancer: a head-to-head observational series

BACKGROUND: Olaparib, a poly ADP-ribose polymerase (PARP) inhibitor, has proven to be effective and safe as maintenance therapy and multiline therapy in ovarian cancer, especially in patients with BRCA mutations. This study intended to observe the influence of tumor load on the efficacy and safety of olaparib in recurrent ovarian cancer. CASES PRESENTATION: Three patients harbored gBRCAwt with low tumor load (LTL), while two women harbored BRCAmt with high tumor load (HTL) were recruited. Two of the three LTL patients achieved partial response, and the other showed stable disease. Both HTL patients were assessed to have progressive disease in a short time. Olaparib appears to be effective and safe for LTL recurrent ovarian cancer patients even if it is gBRCAwt, while the response is poor in HTL patients. CONCLUSIONS: Tumor load may be another potential marker to predict the effect of PARP inhibitors. The present head-to-head observational series provides new evidence on this issue for further research from bench to bedside in the future.