This is a pilot study to investigate the effects of achieving adequate vitamin D levels via ultra-high-dose vitamin D supplementation given prior to hematopoietic stem cell transplant on transplant-related complications and inflammatory biomarkers.

Up to 70% of patients have vitamin D deficiency prior to hematopoietic stem cell transplant (HSCT). Patients with sufficient Vitamin D levels (>50nm/L) prior to allogeneic transplant have significantly better overall survival (OS) and lower rates of rejection and relapse. Vitamin D inhibits Th1 and augments Th2 cell development. Patients who receive vitamin D supplementation during allogeneic transplant have less inflammatory-mediated processes such as chronic graft versus host disease (GVHD) and lower levels of naïve CD8+ cells and CD40 ligand. Multiple studies have raised concern regarding the adequacy of standard and high-dose vitamin D dosing for vitamin D deficiency. A single oral ultra-high dose of Vitamin D given prior to HSCT has been shown to be a safe and well tolerated method of sustaining therapeutic Vitamin D levels for 6-19 weeks.

This is a pilot study to investigate the dynamic changes in inflammatory biomarkers following ultra-high-dose vitamin D supplementation. The study population is patients with total vitamin D level \

Inclusion Criteria:

• Patients who are preparing for HSCT
• If a patient is receiving an autologous transplant, enrollment must occur prior to first transplant in the case that the patient is planned for multiple transplants

Exclusion Criteria:

• Uncorrected hypocalcemia or hypophosphatemia
• Patients in the ICU or on renal replacement therapy
• Patients who have had an allogeneic transplant within the past 12 months prior to enrollment

Enrolled patients with 25OHD level ≤50 ng/mL continue on study