- Prior therapy: No line limit but no more than 1 prior regimens in the platinum resistant setting; no prior treatment targeting the ATR/checkpoint kinase 1 (CHK1) pathway and no prior gemcitabine as single agent; hormonal therapies immunotherapy, and antiangiogenic therapies (as single agents) do not count as lines; poly (adenosine diphosphate [ADP]-ribose) polymerases (PARP)-inhibitors count as line of therapy; prior carboplatin/gemcitabine is allowed provided that there was no disease progression within 12 months after completion of the carboplatin/gemcitabine regimen; subjects may begin protocol treatment at least 4 weeks or 5 half-lives, whichever is shorter, after their last dose of chemotherapy or hormonal therapy, assuming they are otherwise eligible