A randomized, open-label, multicenter, phase 3 study to evaluate the efficacy and safety of Avelumab in combination with chemotherapy followed by maintenance therapy of Avelumab in combination with the poly (adenosine diphosphate [Adp] - ribose) polymerase (Parp) inhibitor talazoparib in patients with previously untreated advanced ovarian cancer (JAVELIN OVARIAN PARP 100) [B9991030]