A Comparative Analysis of Low Dose Grafalon® Versus Thymoglobuline® as Serotherapy in Hematopoietic Stem Cell Transplant in Pediatric and Young Adult Population.

Anti-thymocyte globulin (ATG) forms an essential component of conditioning in hematopoietic stem cell transplantation (HSCT). Due to the shift of donor preference to alternate donors, reliance on rabbit-ATG (rATG) has increased. Two different forms of rATG (Thymoglobuline^® and Grafalon^®) are available for clinical use but data to support the use of one over the other is sparse. We retrospectively analyzed data of 144 patients who underwent allogenic-HSCT for benign hematological conditions at our center, from August 2019 to August 2023. Of these, 87 received Grafalon^® and 57 received Thymoglobuline^®. The majority (77.7%) underwent HSCT for hemoglobinopathies and all received pre-transplant immunosuppression. Engraftment kinetics was similar in 2 cohorts. Six patients had primary graft failure (PGF). There was no difference in the incidence of PGF stratified by serotherapy. Overall survival(OS) for the cohort was 74.9%. Kaplan-Meier estimate of OSand EFSwas significantly better in Grafalon^® group than Thymoglobuline^® (84.4 ± 0.04% vs 64.1% ±0.065%) (p-value= 0.04%) and (84.4 ± 0.04% and 61.2%±0.065% (p-value = 0.01)). Extensive chronic GVHD was (14%) higher in Thymoglobuline^® group and (2.3%) in Grafalon^®. Immune reconstitution at day + 100 was not statistically different between the two groups. On univariate analysis, Thymoglobuline^® serotherapy (OR (95% CI) =4.665 (1.2-18.04))was associated with increased risk of acute grade III-IV GvHD. In our study, Grafalon^® tended to have better OS, decreased incidence of acute grade III-IV GvHD, and extensive cGVHD. There was no difference in engraftment kinetics, PGF, and immune reconstitution between 2 cohorts of serotherapy.