Gemcitabine and capecitabine for heavily pre-treated metastatic colorectal cancer patients--a phase II and translational research study.

We investigated the efficacy and safety of capecitabine and gemcitabin (GemCap) in heavily pre-treated, therapy-resistant metastatic colorectal cancer (mCRC) patients and the clinical importance of cell-free DNA (cfDNA) measurement. Patients' inclusion criteria included histopathologically-verified mCRC refractory to standard chemotherapy, adequate organ function and performance status. Treatment included capecitabine (2,000 mg/m(2) day on days 1-7 q2w) and gemcitabine (1,000 mg/m(2) on day 1). The number of DNA alleles was measured in pre-treatment plasma samples using an in-house developed qPCR. Forty-nine patients were included in the study. GemCap was well-tolerated in the majority of patients. Disease control rate was 30%, median progression-free survival (PFS) and overall survival (OS) by intention-to-treat were 2.7 (95%CI=2.6-2.8) and 6.8 (95%CI=5.0-7.7) months. Median OS in patients with cfDNA concentrations above the median (13,200 alleles/ml) was 4.7 (3.7-9.6) months compared to 7.8 months in the remaining patients (HR=2.22; 1.07-3.9; p=0.0186). The prognostic value of the cell-free DNA (cfDNA) was confirmed by multivariate analysis. GemCap was well-tolerated with encouraging efficacy, and cfDNA was shown to hold a strong prognostic value.