This document provides recommendations for sponsors of investigational new drug applications (INDs) and biologics license applications (BLAs) under 42 U.S.C. § 262 and 21 CFR Parts 312 and 601 on the use of pharmacokinetic (PK)-based criteria to support the approval of alternative dosing regimens for programmed cell death receptor-1 (PD-1) or programmed cell death-ligand 1 (PD-L1) blocking antibodies. This guidance is based on accumulated scientific and regulatory experience for PD-1 and PD-L1 drugs, and as such, does not address development of alternative dosing regimens for other drugs or biologics, changes in route of administration, or novel formulations of previously-approved PD-1/PD-L1 products.