A Study to Evaluate Axatilimab Versus Best Available Therapy in Participants With Chronic Graft Versus Host Disease After at Least 2 Prior Lines of Systemic Therapy

Inclusion Criteria:

• Age ≥ 12 years at the time of signing the ICF.

• Active, moderate to severe cGVHD, requiring systemic immune suppression.

• Participants with refractory or recurrent cGVHD who have received at least 2 linesof systemic therapy, including corticosteroids and ruxolitinib.

• Concomitant use of systemic corticosteroids is allowed. Participants on systemiccorticosteroids must be on a stable dose of corticosteroids for at least 2 weeksprior to C1D1. Topical and inhaled corticosteroid agents are allowed.

• Participants must accept to be treated with one of the following BAT options onC1D1: CNI (cyclosporine or tacrolimus), ECP, MMF, an mTOR inhibitor (everolimus orsirolimus), rituximab, pentostatin, proteasome inhibitors, imatinib, or ibrutinib.

• History of allo-HCT from any donor HLA type (related or unrelated donor with anydegree of HLA matching) using any graft source (bone marrow, peripheral blood stemcells, or cord blood). Recipients of myeloablative, nonmyeloablative, orreduced-intensity conditioning are eligible.

Exclusion Criteria:

• Receipt of more than 1 prior allo-HCT. Prior autologous HCT is allowed.

• Evidence of relapse of hematologic disease or treatment for relapse after theallo-SCT was performed, including DLI for the treatment of molecular relapse. Note:Participants who have received a scheduled DLI as part of their transplant procedureand not for management of malignancy relapse are eligible.

• Systemic treatment with CNIs or mTOR inhibitors started within 2 weeks prior toC1D1.

• Severe renal impairment, that is, estimated creatinine clearance < 30 mL/minmeasured or calculated by Cockcroft-Gault equation in adults and Schwartz formula inpediatric participants, or end-stage renal disease on dialysis.

• Impaired liver function, defined as total bilirubin > 1.5 × ULN and/or ALT and AST > 3 × ULN in participants with no evidence of liver cGVHD.

• History of acute or chronic pancreatitis.

• Active, symptomatic myositis.

• Pregnant or breastfeeding.

Other protocol-defined Inclusion/Exclusion Criteria may apply.