RecruitingPhase 2Biological interventionAxatilimab in Combination With Extracorporeal Photopheresis (ECP) in Chronic Graft-versus-Host DiseaseThe purpose of this study is to see whether giving participants a combination treatment of Axatilimab and Extracorporeal Photopheresis (ECP) is effective against chronic Graft-versus-Host Disease (cGVHD).