Effects of Axatilimab on Skin in Chronic Graft-versus-Host Disease

Chronic graft-versus-host disease (cGVHD) is a condition that can develop after a stem cell transplant. It occurs when donor immune cells attack the body's tissues. In many people, cGVHD affects the skin, causing inflammation, thickening, and scarring that can limit movement and reduce quality of life. Axatilimab is a medicine approved by the U.S. Food and Drug Administration (FDA) to treat adults with cGVHD after at least two previous treatments have not worked well enough. Although axatilimab can improve cGVHD, researchers do not fully understand how it changes immune cells in the skin. The purpose of this study is to learn how axatilimab affects immune cells in the skin and blood of people with cGVHD. Researchers will study skin and blood samples collected before and after participants start axatilimab. The goal is to better understand how the medicine reduces inflammation and scarring and to identify biological changes that occur during treatment. This is an observational research study. The study does not decide whether participants receive axatilimab, when treatment starts, or what dose they receive. All treatment decisions are made by the participant's treating physician as part of routine medical care. About 15 adults with cGVHD involving the skin will participate. Ten participants who are starting axatilimab as part of their usual care will have three study visits: before treatment begins, about 2 weeks after starting treatment, and about 12 weeks after starting treatment. At each visit, participants will provide a small skin biopsy and a blood sample. Five participants with cGVHD who are not receiving axatilimab will serve as a comparison group and will complete one study visit with one skin biopsy and one blood sample. Researchers will also review participants' medical records and collect information about their skin disease over time. Information from this study may help researchers better understand how axatilimab works in people with cGVHD. The findings may also help improve future research and guide the development of treatments for cGVHD and other diseases that cause tissue scarring.