PURPOSE: Consensus molecular subtypes (CMSs) were evaluated as prognostic and predictive biomarkers of patients with RAS wild-type metastatic colorectal cancer (mCRC) receiving fluorouracil and folinic acid (FU/FA) with or without panitumumab (Pmab) after Pmab + mFOLFOX6 induction within the randomized phase II PanaMa trial. METHODS: CMSs were determined in the safety set (ie, patients that received induction) and full analysis set (FAS; ie, randomly assigned patients who received maintenance) and correlated with median progression-free survival (PFS) and overall survival (OS) since the start of induction or maintenance treatment and objective response rates (ORRs). Hazard ratios (HRs) and 95% CI were calculated by univariate/multivariate Cox regression analyses. RESULTS: Of 377 patients of the safety set, 296 (78.5%) had available CMS data: CMS1/2/3/4: 29 (9.8%)/122 (41.2%)/33 (11.2%)/112 (37.8%) and unclassifiable: 17 (5.7%). The CMSs were prognostic biomarkers in terms of PFS ( P < .0001), OS ( P < .0001), and ORR ( P = .02) since the start of induction treatment. In FAS patients (n = 196), with CMS2/4 tumors, the addition of Pmab to FU/FA maintenance therapy was associated with longer PFS (CMS2: HR, 0.58 [95% CI, 0.36 to 0.95], P = .03; CMS4: HR, 0.63 [95% CI, 0.38 to 1.03], P = .07) and OS (CMS2: HR, 0.88 [95% CI, 0.52 to 1.52], P = .66; CMS4: HR, 0.54 [95% CI, 0.30 to 0.96], P = .04). The CMS interacted significantly with treatment in terms of PFS (CMS2 v CMS1/3: P = .02; CMS4 v CMS1/3: P = .03) and OS (CMS2 v CMS1/3: P = .03; CMS4 v CMS1/3: P < .001). CONCLUSION: The CMS had a prognostic impact on PFS, OS, and ORR in RAS wild-type mCRC. In PanaMa, Pmab + FU/FA maintenance was associated with beneficial outcomes in CMS2/4, whereas no benefit was observed in CMS1/3 tumors.

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. 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. 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). 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.

Primary tumor (PT) sidedness is an established prognostic marker in metastatic colorectal cancer (mCRC) and has a predictive impact on the efficacy of anti-epidermal growth factor receptor (anti-EGFR) antibody [monoclonal antibody (mAb)] in patients with RAS wild-type mCRC. This investigation focuses on patients with BRAF^V600E-mutated (BRAFmt) mCRC and examines the efficacy of anti-EGFR mAbs in relation to primary tumor sidedness (PTS). This pooled analysis was carried out using individual patient data from five randomized studies in the first-line setting of mCRC. The population of interest was limited to patients with BRAFmt mCRC and known PTS. For analysis, treatment was stratified into two groups: those treated with anti-EGFR mAbs and those without. Dichotomous variables, such as overall response rate and objective response rate (ORR), were compared using chi-square or Fisher's exact test. Time-to-event endpoints [progression-free survival (PFS) and overall survival (OS)] were analyzed using the Kaplan-Meier method, log-rank test, and Cox regression. An interaction test was carried out via Cox regression. A total of 102 patients with BRAFmt mCRC were identified. The type of targeted therapy (anti-EGFR-based versus non-anti-EGFR) did not significantly impact the outcome. However, in patients with left-sided primary tumors, anti-EGFR mAb-based treatment, compared with non-anti-EGFR, was associated with a higher ORR (58% versus 34%; P < 0.01), trended toward improved PFS [hazard ratio (HR) 0.62; 95% confidence interval (CI) 0.34-1.13; P = 0.12], and demonstrated prolonged OS (HR 0.38; 95% CI 0.20-0.72; P < 0.01). In patients with right-sided primary tumors, anti-EGFR-based therapy had no effect on ORR (33% versus 36%; P > 0.99), induced inferior PFS (HR 1.97; 95% CI 1.12-3.47; P = 0.02), and trended toward a worse OS (HR 1.76; 95% CI 0.99-3.13; P = 0.05). This analysis suggests that PTS has predictive value for the efficacy of anti-EGFR mAb in the first-line treatment of BRAFmt mCRC.