Poly (ADP-Ribose) Polymerase Inhibitors in Patients With Urothelial Cancer.

Poly ADP-ribose polymerase inhibitors (PARPis) have clinical activity in several cancers. The rationale of their therapeutic use in urothelial cancer (UC) resides in the high homologous-recombination repair (HRR) deficiency (HRD) prevalence and potential cross-sensitivity with platinum-based chemotherapy (PBCT). This review aims to summarize and analyze trials exploring the activity of PARPis in UC, focusing on patients who may benefit from those agents, the best clinical setting for the treatment and the benefit of the association with immune-checkpoint inhibitors (ICIs). We included all the available trials analyzing the activity of PARPis in UC in neoadjuvant, adjuvant, first or subsequent lines, and maintenance setting. We included PARPis in monotherapy and in association with other agents. The results in the maintenance setting are intriguing: ATLANTIS trial showed signals of improved progression-free survival in patients with known HRR aberrations, although the Meet-URO12 trial, with its negative results, suggested the failure of clinical selection based on platinum sensitivity only. Single-agent PARPis in pretreated patients showed discouraging results in an unselected population of chemo-refractory patients. Concerning the association of PARPis with ICIs, several trials are exploring their role in platinum-naïve setting; the results in the advanced setting were globally negative. Prior selection of HRD status is essential to identify patients who might benefit from PARPis. The ideal clinical settings seem to be the maintenance treatment and the combination with ICIs in platinum-naïve patients. Definitive results of ongoing and further trials will delineate the position for PARPis, if any, in UC therapy.