Outcome of patients with KRAS exon 2 wildtype (KRAS-wt) metastatic colorectal carcinoma (mCRC) with cetuximab-based first-line treatment in the noninterventional study ERBITAG and impact of comorbidity and age.

Abstract

651 Background: Cetuximab in combination with irinotecan- or oxaliplatin-based chemotherapy has shown to increase ORR, PFS, OS of KRAS-wt mCRC patients (pts). ERBITAG aimed to evaluate safety and efficacy of cetuximab in combination with various first-line chemotherapy regimens in pts with unresectable KRAS-wt mCRC. Methods: KRAS-wt pts on a cetuximab-based first-line treatment with written informed consent could be enrolled in this prospective, non-interventional study. Primary endpoint was ORR, secondary endpoints were amongst others PFS, OS, TTF, and resection rate of liver metastasis. Comorbidities were documented and evaluated by the Charlson Comorbidity Index (CCI). Results: 817 eligible KRAS-wt mCRC pts were enrolled at 144 sites across Germany, documentations for 456 pts were finalised and evaluated. The median age was 65 [27-87] yrs, with 51.5% ≤65 yrs, 34.0% >65-75 yrs, and 14.5% >75 yrs. ECOG performance status was 0, 1, 2, or missing in 34.4%, 49.6%, 8.8%, and 7.2% of pts, respectively. CCI was 0 in 54.4%, and ≥1 in 45.6%. Resection of liver and/or lung metastases was done in 17.3% of pts, 13.4% were R0 resected. For pts with liver limited disease resection rate and R0-rate were 29.3% and 23.8%, respectively. Pts with CCI 0 had no different outcome regardless of age (table). Pts with CCI ≥1 and >75 yrs had a lower ORR and decreased TTF, pts >65-75 yrs had only a decreased TTF as compared to the ≤ 65 yrs age group (table). Conclusions: In this large observational trial outcomes (ORR and PFS) of KRAS-wt mCRC pts on a cetuximab-based first-line treatment were comparable to those reported in pivotal trials. Pts older than 75 yrs without comorbidities (CCI =0) showed no difference to younger pts in ORR, PFS, and TTF. Pts >75 yrs with CCI ≥ 1 had a significant lower ORR and decreased TTF. Clinical trial information: http://www.vfa.de/de/arzneimittel-forschung/datenbanken-zu-arzneimitteln/nisdb/nis-details/_455. [Table: see text]