PD-1/PD-L1 immune checkpoint inhibitors in neoadjuvant therapy for solid tumors (Review)

A comprehensive search regarding programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) inhibitor monotherapy or combination therapy in neoadjuvant settings of 11 types of solid cancer was performed using the PubMed, Cochrane and Embase databases, and the abstracts of various conferences were screened. Data presented in 99 clinical trials indicated that preoperative treatment with PD-1/PD-L1 combined therapy, particularly immunotherapy plus chemotherapy, could achieve a higher objective response rate, a higher major pathologic response rate and a higher pathologic complete response rate, as well as a lower number of immune-related adverse events compared with PD-1/PD-L1 monotherapy or dual immunotherapy. Although PD-1/PD-L1 inhibitor combination caused more treatment-related adverse events (TRAEs) in patients, most of the TRAEs were acceptable and did not cause marked delays in operation. The data suggest that patients with pathological remission after neoadjuvant immunotherapy exhibit improved postoperative disease-free survival compared with those without pathological remission. Further studies are still required to evaluate the long-term survival benefit of neoadjuvant immunotherapy.