In a phase 2 trial, high-dose cyclophosphamide (PTCy) and tacrolimus with or without low-dose anti-thymoglobulin (ATG) showed potential as graft vs host disease (GVHD) prophylaxis in patients with lymphoid malignancies. Trial results were reported in the journal Frontiers in Medicine.

Patients with acute lymphoblastic leukemia (20 patients) or T-cell lymphoma (3 patients) were enrolled in this trial (ClinicalTrials.gov Identifier: NCT04118075) and underwent allogeneic hematopoietic stem cell transplantation. Fludarabine, etoposide, and busulfan were given to all patients.

For GVHD prophylaxis, patients with human leukocyte antigen (HLA)-matched related donors (MSD) were given PTCy and tacrolimus, while those with HLA-matched unrelated (MUD) or haploidentical donors received ATG after neutrophil engraftment, in addition to PTCy and tacrolimus. The primary endpoint was the incidence of grade 2 to 4 acute GVHD in the first 100 days following transplantation.


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A total of 7 patients received transplants with MSDs, 2 with MUDs, and 14 with haploidentical donors. The median patient age was 29 years. The median study follow-up was 303 days, and acute GVHD developed in 3 patients overall, at grade 1 for 1 patient and grade 2 for 2 patients. The 100-day incidence of acute GVHD was 13.0±5.1%, and for acute GVHD of grades 2 to 4, it was 9.1±6.1%.

Chronic GVHD was reported in 3 patients, considered mild in 2 patients, and moderate in 1 patient. The 1-year cumulative incidence of chronic GVHD was 15.2±8.7%, and for moderate or severe chronic GVHD it was 4.6±4.4%.

The 1-year cumulative incidence of relapse was 12.8±9.2%. The 1-year overall survival was 95.5±4.4% and event-free survival was 82.6±9.5%. The 1-year rate of GVHD- and relapse-free survival was 68.0±11.3%. The 100-day and 1-year nonrelapse mortality rates were both 4.6±4.4%.

Cytomegalovirus (CMV) reactivation was reported in 14 of 16 patients with MUD or haploidentical donor transplants, and in 2 of 7 patients with MSD transplants, which the researchers considered to be a high incidence across the study population. One patient died from CMV pneumonia. Epstein-Barr reactivation occurred in 2 patients without posttransplantation lymphoproliferative disease.

The researchers considered the use of ATG to be a possible contributor to the incidence of CMV reactivation in this study, and they mentioned the possibility of adjusting this part of the protocol in future research, such as through a dose reduction or addition of letermovir. The researchers considered their initial data to suggest that the GVHD prophylaxis protocol used in this study may reduce risks of GVHD and nonrelapse mortality, but they recommended further research.

Reference

Jiang JL, Gao WH, Wang LN, Wan M, Wang L, Hu J. Post-transplantation cyclophosphamide, tacrolimus and low-dose ATG as GVHD prophylaxis for allogeneic peripheral stem cell transplantation for adult patients with lymphoid malignancies: a single arm phase II study. Front Med (Lausanne). 2021;8:630160. doi:10.3389/fmed.2021.630160