Background: Chemotherapy dose modification to manage adverse events is commonplace in clinical practice. This exploratory analysis evaluates the impact of liposomal irinotecan dose modification on overall survival (OS) and progression-free survival (PFS) in the NAPOLI-1 clinical trial (NCT01494506). Methods: Analysis includes only patients enrolled under protocol version 2 who received at least the first 2 scheduled doses of study drug. Within the liposomal irinotecan +5 fluorouracil/leucovorin (5 FU/LV) arm, patients were grouped according to whether or not they had a dose modification within the first 6 weeks. Dose reduction was defined as any decrease from initial dose; dose delay was any dosing delay >3 days from target date. OS and PFS (Kaplan-Meier estimates) were compared within the liposomal irinotecan+5-FU/LV arm and between treatment arms. Unstratified hazard ratios (HRs) were calculated using Cox regression analysis. Results: Of the 93 patients from the liposomal irinotecan+5 FU/LV arm included in the analysis, 53 experienced a dose modification (both delay and reduction, n = 30; delay only, n = 19; reduction only, n = 4). No apparent difference in median OS or PFS was observed between patients who did versus patients who did not have a dose modification (OS: 8.4 vs 6.7 months; HR, 0.89; PFS: 4.2 vs 3.1 months; HR, 0.74). Conclusion: An early dose reduction or delay of liposomal irinotecan+5-FU/LV in the first 6 weeks does not significantly impact OS or PFS compared to patients without dose modifications. This finding suggests that tolerability-guided dose modification of liposomal irinotecan does not adversely affect efficacy outcomes.
