First-line cetuximab-based chemotherapies for patients with advanced or metastatic KRAS wild-type colorectal cancer.

Colorectal cancer (CRC) is one of the most commonly occurring cancers worldwide. A burgeoning number of studies have demonstrated that the addition of cetuximab to another standard first-line regimen markedly improves the outcome of CRC treatment. However, at present, the efficacy and safety of cetuximab-based combination chemotherapy has not been well described in Japan. The aim of the present study was to evaluate the efficacy and safety of first-line chemotherapies that included cetuximab for patients with advanced or metastatic Kirsten rat sarcoma viral oncogene homolog (KRAS) wild-type CRC in Japan. This prospective multicenter observational study was conducted at 13 affiliated medical institutions. A total of 64 patients were enrolled between 2010 and 2013. The patients met the following criteria for eligibility: i) histologically confirmed, advanced or metastatic KRAS wild-type CRC; and ii) cetuximab-based chemotherapies administered as a first-line treatment. First-line cetuximab-based treatments were administered as follows: 29 patients (45.3%) received a combination of infusional fluorouracil, leucovorin and oxaliplatin; 14 patients (21.9%) received a combination of capecitabine and oxaliplatin; and 10 patients (15.6%) received a combination of infusional fluorouracil, leucovorin and irinotecan. The overall response rate (including complete plus partial responses) was 50% (32/64 patients). Initially, 48 lesions were diagnosed as unresectable. Among those, 13 lesions (27.1%) were converted to a resectable status following cetuximab-based combination chemotherapy treatments. The median overall survival time and the progression-free survival time were 1,189 and 359 days, respectively. The most frequent grade 3/4 adverse event was neutropenia, which occurred in 20.3% of the patients. The incidence of grade 3/4 skin toxicity was 17.2% (11/64 patients). Cetuximab-based therapies may represent a promising first-line regimen for patients with advanced or metastatic KRAS wild-type CRC in Japan. In addition, this combination was associated with a low incidence of serious toxicities.