Safety of Same-Day Vitamin B12 Supplementation in Patients Receiving Pemetrexed for the Treatment of Non–Small-Cell Lung Cancer or Pleural Mesothelioma: A Retrospective Analysis

Abstract Background Pemetrexed is a folate analog inhibitor for the treatment of non–small-cell lung cancer (NSCLC) and malignant pleural mesothelioma. Folic acid and vitamin B12 supplementation before initiating pemetrexed is necessary because of high rates of cytopenias without supplementation. However, the timing of supplementation has not been thoroughly investigated. Patients and Methods This was a single-center, retrospective study investigating patients receiving pemetrexed from January 1, 2012, to June 30, 2015, who received same-day vitamin B12 supplementation versus ≥ 1 day before pemetrexed. The objective was to evaluate safety outcomes in patients who received vitamin B12 on the same day as pemetrexed (group A) versus vitamin B12 ≥ 1 day (group B) before pemetrexed. Results Two hundred eighty-one patients met the inclusion criteria: 137 patients in group A (same-day administration of vitamin B12) and 144 patients in group B (median time of vitamin B12 administration before pemetrexed, 7 days; range, 1-42 days). Mean changes in hematologic indices from cycle (C) 1 to C2 or C2 to C3 did not differ significantly between groups. There were no significant differences in clinical events between C1 and C2 or C2 and C3 requiring supportive care. There was a significant difference noted in treatment delay in C3 [28/114 (24.6%) group A vs. 14/118 (11.9%) group B, P  = .0164]. In group A, significant predictors of delay in C3 were baseline hemoglobin (mean 13.3 g/dL vs. 12.4 g/dL, P  = .0137) and ANC (mean 6 × 10 9 /L vs. 5 × 10 9 /L, P  = .0003). Conclusion Same-day vitamin B12 and pemetrexed administration is a safe practice in NSCLC and malignant pleural mesothelioma patients.