Abstract
Little is known about the clinical impact of salvage panitumumab with irinotecan for metastatic colorectal cancer (mCRC) patients. The present study conducted a single-arm, multicenter phase II trial for mCRC with skin toxicity prevention program. The subjects were mCRC patients with wild-type KRAS, who showed resistance to fluoropyrimidine, oxaliplatin and irinotecan. Panitumumab was administered at a dose of 6 mg/kg every 2 weeks by intravenous infusion over 60 min, and irinotecan was administered at a dose of 100-180 mg/m(2) every 2 weeks by intravenous infusion over 90 min, depending on the preceding treatment dose. To prevent skin toxicities, a moisturizer was applied and oral antibiotics (100 mg minocycline twice daily) were initiated for 6 weeks. The primary endpoint was the response rate (RR) determined by independent reviewers. Secondary endpoints were the disease control rate (DCR), progression-free survival (PFS) time, overall survival (OS) time and adverse events. A total of 35 patients were enrolled between October 2010 and March 2012. The median age was 61 years (range, 41-76 years), with 25 male and 10 female patients. The initial irinotecan dose was 150 mg/m(2) in 19 patients and 180 mg/m(2) in 1 patient. The remaining patients were treated with ≤120 mg/m(2). A central review indicated a partial response in 8 patients (22.9%) and stable disease in 6 patients (17.1%), with an RR of 22.9% (95% confidence interval, 12.1-39.0) and a DCR of 40%. The RR of the patients with standard-dose irinotecan (150 or 180 mg/m(2)) was 30%, although that of low-dose irinotecan (100-120 mg/m(2)) was 13%. The median PFS time was 2.7 months, and the median OS time was 6.3 months. A grade 3 or above acne-like rash developed in 25.7% of patients. In conclusion, panitumumab and irinotecan as salvage therapy for mCRC KRAS wild-type patients with skin toxicity prevention exhibits limited efficacy. In particular, the effect of low-dose irinotecan with panitumumab appears to be clinically insignificant. Routine use of skin toxicity prevention is currently under evaluation.