T-cells targeted with anti-CD3 x anti-HER2 bispecific antibody for treatment of women with stage IV breast cancer (phase I): Clinical and immune function results.

2548 Background: Nontoxic immunologic targeting strategies for the treatment of metastatic breast cancer (MBC) are needed. Anti-CD3 activated T cells (ATC) retargeted (armed) with anti-CD3 x anti-Her2 bispecific antibody HER2Bi) exhibit high levels of specific cytotoxicity, proliferate, and secrete cytokines/chemokines. This study was designed to test the safety, survival, persistence, and trafficking of aATC. Methods: We report a phase I trial in 23 patients (pts) with MBC (Her2 0-3+) who received escalating doses of 5, 10, 20, and 40 x 109Her2Bi armed ATC (aATC) twice per week for 4 weeks totaling 40, 80, 160, and 320 x 109 aATC with 300,000 IU/m2/day of IL-2 and GM-CSF 300 µg/m2 twice weekly beginning 3 days before the 1st infusion and ending 1 week after the last infusion. All 7 of the Her2 3+ pts had prior treatment with trastuzumab and most pts had multiple rounds of chemotherapy. Results: Grade III-IV toxicities (NC Immunotherapy Toxicity) by total episodes for 23 pts in decreasing order were chill...