Phase II study of panitumumab, oxaliplatin, 5-fluorouracil, and concurrent radiotherapy as preoperative treatment in high-risk locally advanced rectal cancer patients (StarPan/STAR-02 Study).

BACKGROUND The aim of this phase II study was to assess the activity of panitumumab in combination with oxaliplatin, 5-fluorouracil, and external radiotherapy (RT) as preoperative treatment in locally advanced rectal cancer patients. PATIENTS AND METHODS Patients had rectal adenocarcinoma, cT3N+ or cT4N-/+ stage, located <12 cm from the anal margin. Panitumumab was administered before the start of chemo-RT, and every 2 weeks in combination with 5-fluorouracil-oxaliplatin with concurrent RT. Rectal surgery was carried out 7-8 weeks after the end of neoadjuvant treatment. The primary end point was a pathological complete response rate of 25%. RESULTS Sixty patients were enrolled from February 2007 to October 2009. Fifty-five (91.7%) patients underwent surgery. Rate of pathological complete response was 21.1% (95% confidence interval 10.4% to 31.6%). Pathological downstaging occurred in 33 of 57 (57.9%) patients. Grade 3-4 toxicity during neoadjuvant treatment was diarrhea (38.9%), cutaneous reactions (18.6%), nausea (5.1%), asthenia (3.4%), anorexia (3.4%), and neutropenia (1.7%). One toxic death was observed for diarrhea. CONCLUSIONS In our study, the primary end point is not reached and panitumumab combination treatment was associated with high incidence of grade 3-4 diarrhea. The higher pathological complete response rate in comparison with the results of previous neoadjuvant rectal cancer trials with anti-epidermal growth factor receptor monoclonal antibodies supports further studies necessary to understand the possibility of optimal regimens and sequences with chemo-RT.