Consensus Molecular Subtypes as Biomarkers of Fluorouracil and Folinic Acid Maintenance Therapy With or Without Panitumumab in <i>RAS</i> Wild-Type Metastatic Colorectal Cancer (PanaMa, AIO KRK 0212).

Abstract

Consensus molecular subtypes (CMSs) were evaluated as prognostic and predictive biomarkers of patients with <i>RAS</i> 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. 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. 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 (<i>P</i> < .0001), OS (<i>P</i> < .0001), and ORR (<i>P</i> = .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], <i>P</i> = .03; CMS4: HR, 0.63 [95% CI, 0.38 to 1.03], <i>P</i> = .07) and OS (CMS2: HR, 0.88 [95% CI, 0.52 to 1.52], <i>P</i> = .66; CMS4: HR, 0.54 [95% CI, 0.30 to 0.96], <i>P</i> = .04). The CMS interacted significantly with treatment in terms of PFS (CMS2 <i>v</i> CMS1/3: <i>P</i> = .02; CMS4 <i>v</i> CMS1/3: <i>P</i> = .03) and OS (CMS2 <i>v</i> CMS1/3: <i>P</i> = .03; CMS4 <i>v</i> CMS1/3: <i>P</i> < .001). The CMS had a prognostic impact on PFS, OS, and ORR in <i>RAS</i> 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.