On August 14, 2024, the Food and Drug Administration (FDA) approved axatilimab, a colony stimulating factor-1 receptor (CSF-1R)-blocking antibody, for chronic graft-versus-host disease (chronic GVHD) after failure of at least two prior lines of systemic therapy in adult and pediatric patients weighing at least 40 kilograms (kg). Approval was based on the results of the AGAVE-201 Study (NCT04710576), which included a cohort of 79 patients with chronic GVHD treated with axatilimab 0.3 mg/kg administered intravenously every 2 weeks in an open-label, single-arm cohort. Efficacy was determined by the overall response rate (ORR) through Cycle 7 Day 1, which included complete response (CR) and partial response (PR) according to the 2014 NIH consensus criteria, and the durability of response. The ORR through Cycle 7 Day 1 was 75% (95% CI 64, 84); all responses were PR. The median duration of response was 1.9 months (95% CI: 1.6, 3.5), but 60% (95% CI: 43, 74) of responding patients remained alive without new systemic therapy for at least 12 months from response. The common adverse reactions included infection, increased transaminases, decreased phosphate, decreased hemoglobin, musculoskeletal pain, increased lipase, fatigue, increased amylase, increased calcium, increased creatine phosphokinase, increased alkaline phosphatase, nausea, headache, diarrhea, cough, fever, and dyspnea. FDA issued a postmarket requirement to evaluate safety with long-term use.