Determination of the UGT1A1 polymorphism as guidance for irinotecan dose escalation in metastatic colorectal cancer treated with first-line bevacizumab and FOLFIRI (PURE FIST)

Abstract

Aim: Uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) polymorphism plays a crucial role in the increased susceptibility of patients to irinotecan and its toxicity. This study is a multicenter, randomised clinical trial comparing the clinical outcomes and adverse events (AEs) in metastatic colorectal cancer (mCRC) patients treated with bevacizumab plus FOLFIRI with or without UGT1A1 genotyping and irinotecan dose escalation as the first-line therapy.

Methods: The control group received conventional biweekly FOLFIRI plus bevacizumab without UGT1A1 genotyping, whereas the study group received the same regimen with irinotecan dose escalation based on UGT1A1 genotyping. The primary end-point was progression-free survival (PFS), and secondary end-points were overall response rate (ORR), disease control rate (DCR), overall survival (OS), AEs and metastasectomy rate.

Results: Over a median follow-up of 26.0 months (IQR, 17.0-35.0 months), study group (n = 107) was superior to the control group (n = 106) in PFS, OS, ORR, DCR, and metastasectomy rate (all P < 0.05). Furthermore, there were no significant differences in AEs ≥ grade III between the two groups, even with the 1.36-fold increase in the relative dose intensity of irinotecan in the study group. Dose escalation of irinotecan, an independent factor of ORR (P < 0.001) and DCR (P = 0.006), improved PFS in mCRC patients with wild-type and mutant KRAS (P = 0.007 and P = 0.019, respectively).

Conclusion: The current study revealed that mCRC patients, regardless of KRAS gene status, with UGT1A1 genotyping can tolerate escalated doses of irinotecan and potentially achieve a more favourable clinical outcome without significantly increased toxicities.

Clinical trial registration: NCT02256800.

Keywords: Bevacizumab; Dose escalation; FOLFIRI; First-line treatment; Irinotecan; Metastatic colorectal cancer; UGT1A1 polymorphism.