Although results of the phase II BAYOU trial indicated that addition of olaparib to durvalumab in patients with metastatic urothelial carcinoma did not improve PFS or OS, the combination did appear beneficial in the subgroup of patients with HRD, supporting the continued investigation of PARP inhibitor and PD-(L)1 inhibitor combinations in urothelial cancer [50]. The gene discussed is PARP1; the disease is hypoparathyroidism-retardation-dysmorphism syndrome.