To Compare the Efficacy of the Addition of Methotrexate (MTX) to Current Standard Acute Graft-versus-host Disease (GVHD) First-line Treatment With Corticosteroids

Phase III randomized double-blinded trial designed to compare the efficacy of the addition of MTX to current standard acute GVHD first-line treatment with corticosteroids. The protocol will use a novel endpoint for benchmarking interventions based on a composite primary endpoint of GVHD-free and corticosteroids-free survival.

The primary endpoint of the trial will be the assessment of a composite endpoint of graft-versus-host disease-free and corticosteroids-free survival at 12 months after randomization

This is a phase III randomized, multicenter, double blinded controlled study. Patients who develop clinically meaningful acute GVHD and who meet all other entry criteria will be randomized 1:1 to receive either corticosteroids and placebo ("standard of care", control arm) or the combination of low-dose MTX with corticosteroids as first-line therapy for acute GVHD (MTX; "experimental arm").

The primary analysis of this hypothesis generation study is to estimate the composite endpoint of GVHD-free and corticosteroids-free survival at 12 months after randomization in both treatment arms. In fact, it is more and more established that such composite endpoint is a clinically very relevant one because it represents ideal recovery from allo-SCT (Stem Cell transplantation) (at 1 year after acute GVHD diagnosis) and a measure of cure without ongoing morbidity.

Eligibility Criteria:
Inclusion Criteria:

* Adults patients (\>=18 years old) with hematological diseases, who develop a first episode of acute GVHD (grade II-IV) requiring systemic therapy
* First allo-SCT, with any type of donor, stem cell source, GVHD prophylaxis or conditioning regimen
* Biopsy of acute GVHD target organ is recommended, but not required. Enrollment should not be delayed awaiting biopsy or pathology results
* The patient must have received no previous systemic immune suppressive therapy for treatment of acute GVHD, except for a maximum 72 hours of prior corticosteroid therapy
* Absolute neutrophil count (ANC) greater than 0.5 G/L
* Platelets count greater than 20 G/L
* Signed informed consent
* Affiliation to a social security system (recipient or assign)
* Women who are of childbearing potential must have a negative serum pregnancy test and agree to use a medically acceptable method of contraception until 6 months after the end of treatment.

Men with a partner of childbearing potential must agree to use a medically acceptable method of contraception until 6 months after the end of treatment.

Exclusion Criteria:

* Hyper-acute GVHD as defined by the MD Anderson's criteria (Saliba, de Lima et al. 2007)
* Flare of GVHD in a patient already on corticosteroid treatment
* Overlap chronic GVHD as defined by the NIH Consensus Criteria (Jagasia, Greinix et al. 2015)
* MTX given within 7 days of enrollment
* Active uncontrolled infection
* Relapsed/persistent malignancy requiring rapid immune suppression withdrawal
* Acute GVHD after donor lymphocytes infusion (DLI)
* Other systemic drugs for GVHD treatment (including extra-corporeal photopheresis)
* If any prior steroid therapy (for indication other than GVHD), treatment at doses \> 0.5 mg/kg/day methyl-prednisolone within 7 days prior to onset of acute GVHD
* Patients who are pregnant, breast feeding, or if sexually active, unwilling to use effective birth control for the duration of the study
* Patient on dialysis
* Patients with veno-occlusive disease of the liver or with significant liver abnormalities who in the judgment of the treating physician cannot receive MTX
* Patients requiring after inclusion in the protocol the continuation of one or more of the following medication: probenecide, trimethoprime (alone or in combination with sulfametoxazole), phenylbutazone or yellow fever vaccine
* Patients with a history of intolerance/allergy to MTX
* Hypersensitivity to the active substance or to any of the excipients