ABSTRACT:Sacituzumab govitecan (SG) is an antibody–drug conjugate composed of a Trop‐2–directed antibody coupled to SN‐38. SG is approved in multiple countries for pretreated metastatic triple‐negative breast cancer (mTNBC) and hormone receptor‐positive/human epidermal growth factor receptor 2‐negative (HR+/HER2–) mBC. Three previously developed population pharmacokinetic (PopPK) models for SG, free SN‐38, and total antibody (tAB) in patients with mTNBC or other solid tumors were externally validated using data from 260 patients with HR+/HER2− mBC from TROPiCS‐02 (NCT03901339). Pharmacokinetic parameters were re‐estimated using data from 789 patients with HR+/HER2− mBC, mTNBC, or other solid tumors from three studies—TROPiCS‐02, ASCENT (NCT02574455), and IMMU‐132‐01 (NCT01631552). Previously developed PopPK models adequately described the data from TROPiCS‐02. Typical parameter estimates based on combined dataset for clearance and steady‐state volume of distribution were 0.128 L/h and 3.58 L for SG and 0.0155 L/h and 4.29 L for tAB, respectively. The pharmacokinetics of the three analytes (SG, free SN‐38, and tAB) in participants with HR+/HER2− mBC were consistent with those observed in mTNBC and other tumor types. The analyses confirmed mild‐to‐moderate renal impairment, mild hepatic impairment, age, tumor type (based on limited data in non‐breast cancer tumor types), baseline albumin level, UGT1A1 genotype, or Trop‐2 expression did not have a clinically relevant impact on the exposure of the three analytes across populations. These findings support that the SG dosing regimen of 10 mg/kg on Days 1 and 8 of 21‐day cycles is adequate for patients with HR+/HER2− mBC.