Relevance of vitamin D in patients undergoing HLA matched allogeneic stem cell transplant for acute leukemia

Background: In hematopoietic stem cell transplant (HSCT), vitamin D deficiency has been variably associated with increased complications, primarily graft versus host disease (GvHD), with a potential impact on survival. Results from various studies however, have not been consistent. This analysis was conducted to study the impact of peri-transplant vitamin D levels on transplant outcomes in patients with acute leukemia (AL) who underwent HLA matched (related/unrelated) HSCT.Methods: This was a single center retrospective study. Patients of AL including Acute Lymphoblastic Leukemia (ALL), Acute Myeloid Leukemia (AML) or Mixed Phenotypic Acute Leukemia (MPAL) who underwent fully matched or 9/10 transplants (related/unrelated) between 2008 and 2019 were included. Vitamin D deficiency was defined as serum 25-hydroxy vitamin D3 levels <= 20 ng/ml. Those with deficiency received replacement with oral vitamin D at a dose of 60,000 IU weekly for 8 weeks followed by maintenance with daily vitamin D (800 IU/ day). Vitamin D levels were repeated at 4 months from start of replacement. For patients who received correction, repeat levels >20 ng/ml were considered replete. Based on vitamin D levels in the peri-transplant period (within 120 days of transplant), patients were categorised as either vitamin D replete (> 20 ng/ml) or deplete (<= 20 ng/ml). Peri-transplant vitamin D status was correlated with transplant outcomes.Results: Of the 133 patients included, 31 were deplete (median vitamin D 15.0 ng/ml) and 102 were replete (median vitamin D 34 ng/ml) at time of transplant. Both groups were matched for age, diagnosis, EBMT score and disease risk index (DRI). There were no differences in time to neutrophil or platelet engraftment, CMV reactivation, acute GvHD (aGvHD) or chronic GvHD (cGvHD) between the two groups. Relapse rate, Progression Free Survival (PFS) and Overall Survival (OS) were also comparable between the 2 groups. Conclusion: The incidence of vitamin D deficiency was high in our patient cohort. Patients who were vitamin D deficient at the time of transplant did not have inferior outcomes, suggesting a limited role of vitamin D in influencing transplant outcomes.