PDGFRB and leiomyosarcoma: A classic example would be that of GI tumors for which KIT/PDGFR sequencing is now considered standard of care for determining whether a patient has these alterations and, if so, whether the patient has resistance alterations.17 A developing example would be that in leiomyosarcoma, where we have previously reported that homologous recombination alterations are a common feature of uterine leiomyosarcomas and may be amenable to PARP inhibition.18