A phase I/II study of bevacizumab (beva), erlotinib (erl), and 5-fluorouracil (5-FU) with concurrent external beam radiation therapy (RT) in locally advanced rectal cancer (LARC)

4106 Background: The German Rectal Cancer Study Group established neoadjuvant therapy as a standard of care in patients with T3/T4 rectal cancer. Beva, a vascular endothelial growth factor (VEGF) inhibitor with demonstrated activity in colorectal cancer, and erl, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor may both serve as radiation sensitizers. Methods: Twenty one pts with LARC, defined as T3 or T4 disease by MRI or endorectal ultrasound, were enrolled from May 2006-December 2008. Pts had adequate hepatic, renal and hematopoietic function, and an ECOG performance status of ≤2. Treatment consisted of 5-FU 225 mg/M2/day by continuous infusion for the duration of radiation (50.4 Gy). Beva 5 mg/kg was administered on days 1, 15 and 29. The first cohort received erl 50 mg, the second cohort 100 mg, and third cohort 150 mg daily until completion of radiation. Pts underwent surgery 6–9 weeks following the radiation. The primary endpoints were determination of the maximally tolerated dose (MTD) and pathologic complete response (pCR). Secondary endpoints included toxicity (TOX), local control (LC), progression free survival and median survival. A total of 25 pts will be treated at the MTD. Results: Twenty-one pts began study therapy: 2 withdrew consent prior to completing study therapy, and 2 pts were removed prior to completion for clostridium difficile colitis and cardiac ischemia. No dose limiting toxicities were achieved. Erl 100 mg was chosen as the MTD. Two pts have not yet completed study treatment. Fifteen pts have completed study therapy and have undergone surgery, of whom 7 (47%) have demonstrated a pCR. At a median follow-up of 7 months, there have been no local recurrences in patients who completed study therapy. Grade 3–4 treatment related TOX included: lymphopenia 6 (59%), diarrhea 4 (24%), rash 2(12%), cardiac ischemia 1(6%), transaminitis 1(6%), mucositis 1(6%). One pt developed an anastomotic leak. Conclusions: Beva and erl in combination with infusional 5-FU and RT appears to be a highly active preoperative regimen for locally advanced rectal cancer. [Table: see text]