THURSDAY, Oct. 26, 2017 (HealthDay News) -- Higher HER3 expression is associated with improved survival with the addition of panitumumab treatment for patients with RAS wild-type (wt) advanced colorectal cancer, according to a study published online Oct. 26 in JAMA Oncology.
Jenny F. Seligmann, Ph.D., from the University of Leeds in the United Kingdom, and colleagues assessed HER3 as a prognostic marker and then as a predictive biomarker in patients with RAS wt. The data evaluated were from a randomized clinical trial that tested the addition of panitumumab to irinotecan therapy in patients with KRAS wt advanced colorectal cancer who had experienced failure with previous fluoropyrimidine treatment.
The researchers found that higher HER3 was weakly prognostic for overall survival (OS) in 308 patients (hazard ratio [HR] per twofold change, 0.91; 95 percent confidence interval [CI], 0.83 to 0.99; P = 0.04) but not for progression-free survival (PFS) (HR, 0.93; 95 percent CI, 0.83 to 1.05; P = 0.25). Higher HER3 was predictive; for patients with RAS wt, there was an association with prolonged PFS on irinotecan plus panitumumab (HR, 0.71; 95 percent CI, 0.61 to 0.82; P < 0.001) but not irinotecan (HR, 0.96; 95 percent CI, 0.82 to 1.13; P = 0.65), with a significant interaction between biomarker and treatment (P = 0.001). The interaction for OS was similar (P = 0.004).
"This finding provides insight into the mechanism of anti-EGFR agents and is of potential clinical utility," the authors write.
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