Study Evaluating Biomarkers in Patients With Colorectal Cancer and Native KRAS Treated With Chemotherapy + Cetuximab

Advanced colorectal cancer (ACRC) is a heterogeneous disease and classification of patients is nowadays inefficient. Roughly twenty per cent of patients present with favorable figures (less than 4 liver nodules and less than 5 cm) and are suitable for local treatments (surgery or local-ablative therapies). Additionally, 10-15% of patients have poor performance status (PS \>2) or are severe disabled due to geriatric syndromes or/and co-morbid diseases that preclude any treatment strategies than best supportive care alone. The rest of patients (fit patients not suitable for radical treatments) constitute the population of patients treated with palliative therapies. Despite of it not all these patients have the same prognosis. Patients with PS 0,1 and levels of LDH \<ULN (Intermediate-risk patients) have better PFS and OS irrespective of therapy in all randomized clinical trials (de Gramont et al, JCO 2000; Douillard et al, Lancet 2000; Koopman et al, 2007). CRYSTAL trial shows a benefit in PFS (1.5 months) in RASWT of FOLFIRI plus cetuximab compared with FOLFIRI alone. Nowadays the selection of patients for cetuximab treatment is based on mutational status of KRAS, which allow to select those patients who will not respond to therapy. Other surrogate markers of activity should be also evaluated. Our hypothesis is that the suggested biomarkers will allow the selection of the patients who will benefit the most from the biweekly cetuximab treatment.