PARP1 and Thrombocytopenia: Phase 1 clinical trials with PARP inhibitors in combination with chemotherapeutic agents such as temozolomide, cisplatin, carboplatin, paclitaxel, gemcitabine, or the topoisomerase inhibitor I topotecan showed severe myelosuppression in the form of neutropenia and thrombocytopenia as a side effect (Matulonis and Monk 2017; Yap et al. 2019).