Effective antibody therapy induces host-protective antitumor immunity that is augmented by TLR4 agonist treatment.

Toll-like receptors are potent activators of the innate immune system and generate signals leading to the initiation of the adaptive immune response that can be utilized for therapeutic purposes. We tested the hypothesis that combined treatment with a Toll-like receptor agonist and an antitumor monoclonal antibody is effective and induces host-protective antitumor immunity. C57BL/6 human mutated HER2 (hmHER2) transgenic mice that constitutively express kinase-deficient human HER2 under control of the CMV promoter were established. These mice demonstrate immunological tolerance to D5-HER2, a syngeneic human HER2-expressing melanoma cell line. This human HER2-tolerant model offers the potential to serve as a preclinical model to test both antibody therapy and the immunization potential of human HER2-targeted therapeutics. Here, we show that E6020, a Toll-like receptor-4 (TLR4) agonist effectively boosted the antitumor efficacy of the monoclonal antibody trastuzumab in immunodeficient C57BL/6 SCID mice as well as in C57BL/6 hmHER2 transgenic mice. E6020 and trastuzumab co-treatment resulted in significantly greater inhibition of tumor growth than was observed with either agent individually. Furthermore, mice treated with the combination of trastuzumab and the TLR4 agonist were protected against rechallenge with human HER2-transfected tumor cells in hmHER2 transgenic mouse strains. These findings suggest that combined treatment with trastuzumab and a TLR4 agonist not only promotes direct antitumor effects but also induces a host-protective human HER2-directed adaptive immune response, indicative of a memory response. These data provide an immunological rationale for testing TLR4 agonists in combination with antibody therapy in patients with cancer.

Induction Therapy for Locally Advanced, Resectable Esophagogastric Cancer: A Phase I Trial of Vandetanib (ZD6474), Paclitaxel, Carboplatin, 5-Fluorouracil, and Radiotherapy Followed by Resection.

OBJECTIVES: Preoperative chemotherapy and radiation for localized esophageal cancer produces cure rates near 30% when combined with surgical resection. Vandetanib, a small molecule receptor tyrosine kinase inhibitor of VEGFR-2, VEGFR-3, RET, and EGFR, demonstrated synergy with radiation and chemotherapy in preclinical models. We conducted a phase I study to assess the safety and tolerability of vandetanib when combined with preoperative chemoradiation in patients with localized esophageal carcinoma who were surgical candidates. METHODS: Patients with stage II-III esophageal and gastroesophageal junction carcinoma without prior therapy were enrolled in a 3+3 phase I design. Patients received once-daily vandetanib (planned dosing levels of 100, 200, and 300 mg) with concomitant daily radiotherapy (1.8 Gy/d, 45 Gy total) and chemotherapy, consisting of infusional 5-FU (225 mg/m/d over 96 h, weekly), paclitaxel (50 mg/m, days 1, 8, 15, 22, 29) and carboplatin (AUC of 5, days 1, 29). RESULTS: A total 9 patients were enrolled with 8 having either distal esophageal or gastroesophageal junction carcinomas. All patients completed the planned preoperative chemoradiation and underwent esophagectomy. Nausea (44%) and anorexia (44%) were the most common acute toxicities of any grade. One grade 4 nonhematologic toxicity was observed (gastrobronchial fistula). One additional patient suffered a late complication, a fatal aortoenteric hemorrhage, not definitively related to the investigational regimen. Five (56%) patients achieved a pathologic complete response. Three (33%) additional patients had only microscopic residual disease. Five (56%) patients remain alive and disease free with a median follow-up of 3.7 years and median overall survival of 3.2 years. The maximum tolerated dose was vandetanib 100 mg/d. CONCLUSIONS: Vandetanib at 100 mg daily is tolerable in combination with preoperative chemotherapy (5-FU, paclitaxel, carboplatin) and radiation therapy with encouraging efficacy worthy of future study.

Phase II and coagulation cascade biomarker study of bevacizumab with or without docetaxel in patients with previously treated metastatic pancreatic adenocarcinoma.

PURPOSE: Treatment options are limited for advanced pancreatic cancer progressive after gemcitabine therapy. The vascular endothelial growth factor pathway is biologically important in pancreatic cancer, and docetaxel has modest antitumor activity. We evaluated the role of the anti-vascular endothelial growth factor antibody bevacizumab as second-line treatment for patients with metastatic pancreatic cancer. DESIGN: Patients with metastatic adenocarcinoma of the pancreas who had progressive disease on a gemcitabine-containing regimen were randomized to receive bevacizumab alone or bevacizumab in combination with docetaxel. RESULTS: Thirty-two patients were enrolled; 16 to bevacizumab alone (Arm A) and 16 to bevacizumab plus docetaxel (Arm B). Toxicities were greater in Arm B with the most common grade 3/4 nonhematologic toxicities including fatigue, diarrhea, dehydration, and anorexia. No confirmed objective responses were observed. At 4 months, 2 of the 16 patients in Arm A and 3 of the 16 patients in Arm B were free from progression. The study was stopped according to the early stopping rule for futility. Median progression-free survival and overall survival were 43 days and 165 days in Arm A and 48 days and 125 days in Arm B. Elevated d-dimer levels and thrombin-antithrombin complexes were associated with decreased survival and increased toxicity. CONCLUSION: Bevacizumab with or without docetaxel does not have antitumor activity in gemcitabine-refractory metastatic pancreatic cancer. Baseline and on-treatment d-dimer and thrombin-antithrombin complex levels are associated with increased toxicity and decreased survival.