Molecular hyperselection for optimal choice of eerstelijns targeted therapy independent of primary tumor sidedness: A...

INTRODUCTION: Molecular diagnostics play a pivotal role in guiding therapy for metastatic colorectal cancer (mCRC). Current guidelines recommend stratification based on biomarkers such as RAS, BRAF, and DNA mismatch-repair (MMR) status to select between anti-EGFR (epidermal growth factor receptor) and anti-VEGF (vascular endothelial growth factor) therapies. MATERIALS AND METHODS: This retrospective analysis evaluated the randomized FIRE-3 study that compared first-line treatment with FOLFIRI plus cetuximab to FOLFIRI plus bevacizumab in RAS wild-type patients. The present analysis included 199 patients with RAS/BRAF wild-type MMR proficient tumors. Next-generation sequencing (NGS) was successfully performed in all patients and allowed stratification into hyperselected (no predefined genetic alterations) or gene altered subgroups using the previously published approach of the PRESSING-studies. RESULTS: Hyperselection according to PRESSING-3 was associated with a survival benefit from anti-EGFR-based therapy compared to bevacizumab (38.5 months vs. 27.5 months; HR 0.68; 95 % CI, 0.44-1.05; P = 0.08). This benefit was observed in both, right- and left-sided tumors, (HR 0.58 and HR 0.70). Patients with gene alterations showed inferior survival compared to hyperselected patients across all subgroups. In this unfavorable subgroup, application of cetuximab and bevacizumab were associated with comparable OS (total cohort: HR 1.04; 95 % CI, 0.61-1.79). Again, this finding was independent of primary tumor sidedness (left-sided tumors: HR 1.10; 95 % CI, 0.59-2.07; right-sided tumors: HR 1.05; 95 % CI, 0.31-3.55). CONCLUSION: Molecular hyperselection facilitated by next generation sequencing could replace primary tumor sidedness as a tool of decision making for optimal choice of targeted therapy in first-line treatment of RAS wild-type mCRC.