Results from panitumumab (pmab) regimen evaluation in colorectal cancer to estimate primary response to treatment (PRECEPT): Second-line treatment with pmab and FOLFIRI by tumor KRAS status
Authors: Cohn A. L. , Smith D. A. , Neubauer M. A. , Houston G. , Khandelwal P. , Wiggans R. G. , Zhang K. , Yassine M. 
Published: August 2020

4067^

Background: Pmab, a fully human antibody to the epidermal growth factor receptor (EGFR), is indicated as monotherapy for treatment of metastatic colorectal cancer (mCRC). Mutation status of KRAS in mCRC tumors has recently been shown to predict response to anti-EGFR antibody therapies. The effect of KRAS tumor status on the efficacy of second-line pmab + FOLFIRI was evaluated in this prospective analysis. Methods: Patients (pts) were enrolled in this phase 2, open-label, single-arm study after failure of first-line treatment with oxaliplatin-based chemotherapy + bevacizumab. Pts with unresectable, measurable disease; ECOG status 0/1; with tumor samples available for KRAS testing were eligible. Pts received pmab 6 mg/kg + FOLFIRI Q2W until disease progression or intolerability. Tumor assessments were performed at wks 8, 16, 24, 32, and Q12W thereafter. DNA extracted from fixed tumor sections was used to determine KRAS status by real-time PCR. Efficacy (objective response, progression-free survival [PFS], and overall survival [OS]) and safety were evaluated by KRAS status. Results: In an interim analysis (May 2008) of 115 pts who had received ≥ 1 dose of pmab, 109 pts had known KRAS status (59% had tumors with wild-type [WT] KRAS, 41% had mutant [MT] KRAS tumors), and 102 pts had the opportunity to have their first tumor assessment. Efficacy outcomes by KRAS status are shown ( Table ). Pmab-related AEs were reported in 93% of pts; 87 pts (76%) had ≥ grade 3 AEs (related and unrelated). Most common AEs were skin-related toxicities (86% of pts), diarrhea (72%), and nausea (53%); there was no evidence that incidence of AEs was related to KRAS status. Conclusions: In interim analyses, numerical differences in PFS and OS in favor of pts with WT KRAS were observed. Pmab had a safety profile consistent with other FOLFIRI + pmab trials. Final efficacy and safety data will be presented.

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