Effectiveness and toxicity of high-dose cyclophosphamide in obese versus non-obese patients receiving allogeneic hematopoietic stem cell transplant

Purpose To determine if there is a difference in toxicity and effectiveness between obese and non-obese patients who receive high-dose cyclophosphamide (Cy) prior to allogeneic hematopoietic stem cell transplant (allo-HCT). Methods Patients were included in this study if they were at least 18 years of age and received high-dose Cy in combination with total body irradiation (CyTBI) or busulfan (BuCy) prior to allo-HCT between 1 January 2008 and 29 February 2012. The primary endpoint was the difference in overall toxicity between obese and non-obese patients. Secondary objectives examined differences in effectiveness between groups assessed by relapse at day +100, relapse at 1 year, death at 1 year, chimerisms at days +30, +60, and +90, and incidence of acute graft versus host disease (aGVHD). Results Sixty-one patients met the inclusion criteria, 28 obese and 33 non-obese. Overall toxicity was greater in obese patients compared to non-obese patients (82% vs. 52%, OR 4.3 [95% CI 1.3–14.1]; p = 0.01), which was driven by a greater incidence of renal dysfunction (79% vs. 48%, OR 3.9 [95% CI 1.3–12.1]; p = 0.02). There were no differences in rates of grade 3 or 4 toxicity, hepatic dysfunction, or any measure of effectiveness between groups. Conclusion Obese patients receiving high-dose Cy and allo-HCT are at increased risk for toxicity, although there appears to be no difference in the rate of relapse or survival between obese and non-obese patients.