ZEN003694 Combined With Niraparib in Patients With Metastatic or Recurrent Solid Tumors

PARPis impair the repair of single strand DNA breaks leading to double strand DNA breaks especially in patients with defects in the HR pathway. PARP is have been extensively studied in ovarian cancer and are approved for patients with germline or somatic BRCA mutant ovarian cancer after 2-3 lines of chemotherapy. PARPis have been also approved as maintenance therapy in first line and recurrent ovarian cancer after partial or complete response to platinum-based therapy. PARPis have prominent activity in BRCA mutated cancer with lower activity in the BRCA wild type HRD negative ovarian cancer. Approximately 18-24% of ovarian cancer harbor somatic or germline BRCA mutation and 50% harbor alteration in the homologous recombination (HR) pathway. Further, PARPi therapy is frequently associated with PARPi resistance. Therefore, there is a need to reverse PARPi resistance and enhance response to PARPi in PARPi resistant ovarian cancer. Recently, significant pre-clinical evidence has shown that BETi's synergize with PARPi's through downregulation of the transcription of several HR genes. It is hypothesized that BETi may suppress HR and enhance non-homologous end joining thereby sensitizing HR-proficient cancer cells to PARP inhibition, and also BETi has been described to reverse PARPi resistance. To test this hypothesis, this Phase I trial will test the combination of niraparib and ZEN003694 in recurrent or metastatic solid cancers.