This trial investigated the addition of panitumumab to triplet chemotherapy with fluorouracil/folinic acid, oxaliplatin, and irinotecan (FOLFOXIRI) in a two-to-one randomized, controlled, open-label, phase II trial in patients with untreated wild-type (WT) metastatic colorectal cancer.

The primary end point was objective response rate (ORR) according to RECIST (version 1.1). The experimental arm (modified FOLFOXIRI [mFOLFOXIRI] plus panitumumab) was considered active if the ORR was ≥ 75%. The experimental ORR was compared with an estimated ORR of 60% based on historical data, verified by a randomized control group (FOLFOXIRI). The power of the trial was 80%, with a potential type I error of 0.05. Secondary end points included secondary resection rate, toxicity, progression-free survival, and overall survival.

A total of 63 patients were randomly assigned to the experimental arm and 33 patients to the control arm. The ORR of the mFOLFOXIRI plus panitumumab arm exceeded 75% and was higher when compared with that of FOLFOXIRI (87.3% 60.6%; odds ratio, 4.469; 95% CI, 1.61 to 12.38; = .004). The secondary resection rate was improved with the addition of panitumumab (33.3% 12.1%; = .02). Progression-free survival was similar in the study arms, whereas overall survival showed a trend in favor of the panitumumab-containing arm (hazard ratio for death, 0.67; 95% CI, 0.41 to 1.11; = .12).

The addition of panitumumab to mFOLFOXIRI in patients with WT metastatic colorectal cancer improved the ORR and rate of secondary resection of metastases and represents a treatment option in selected and fit patients in need of highly active first-line therapy. Future studies should determine whether the addition of panitumumab to mFOLFOXIRI prolongs survival.