Capecitabine, Oxaliplatin, Irinotecan, and Bevacizumab Combination Followed by Pazopanib Plus Capecitabine Maintenance for High-Grade Gastrointestinal Neuroendocrine Carcinomas

Objectives: Gastrointestinal neuroendocrine carcinoma (NEC) is a lethal, uncommon, and understudied neoplasm. We present the efficacy and safety of first-line capecitabine (CP), oxaliplatin, irinotecan, and bevacizumab (CAPOXIRI-BEV) combination followed by pazopanib plus CP maintenance therapy in patients with advanced high-grade poorly differentiated gastrointestinal NEC. Methods: This was a two-stage phase II study conducted at multiple institutions. Patients were consecutively enrolled and had advanced NEC of the colon or small bowel. Patients received irinotecan 125 mg/m(2), oxaliplatin 80 mg/m(2) on day 1, CP 1000 mg/m(2) twice daily on days 1 to 14, plus bevacizumab 8 mg/kg on day 1 for six 21-day cycles. Maintenance therapy was given to those who responded (complete response/partial response) or had stable disease after 6 cycles with CAPOXIRI-BEV with pazopanib 800 mg daily plus CP 1600 mg/m(2) daily on days 1 to 14 every 3 weeks until disease progression or unacceptable toxicity. Patients who progressed on CAPOXIRI-BEV received standard etoposide-carboplatin. The primary endpoint was overall response rate. Results: Twenty-two patients were enrolled of whom 19 were evaluable. The median age was 60 years. The overall response rate (3 complete response/6 partial response) was 47.4% (95% confidence interval: 29.5-76.1), the overall disease control rate was 78.9% (95% confidence interval: 62.6-99.6), and, at median 30 (11 to 41 mo) months' follow-up, 5 patients (26.3%) were still alive. Median progression-free survival was 13 months, and the 1-year progression-free survival rate was 52.6%. The median overall survival was 29 months. The median overall survival of the 9 patients who responded versus those with stable disease/progressive disease was 30.5 versus 14 months, respectively. The median duration of response was 16 months. Predictable toxicity was observed. Conclusions: First-line CAPOXIRI-BEV followed by pazopanib plus CP maintenance therapy for advanced NEC demonstrates promising efficacy and predictable toxicity. Further investigation is warranted.