NK Cell Infusions With Trastuzumab for Patients With HER2+ Breast and Gastric Cancer

Recently, targeted immunotherapies have become part of the therapeutic arsenal in adult solid tumors, and have shown promising activity in melanomas and prostate cancers. Trastuzumab is a monoclonal antibody that targets HER2 and is used routinely in combination with chemotherapy in HER2 over-expressing breast and gastric cancer. Trastuzumab is known to induce antibody dependent cell cytotoxicity (ADCC), among its various mechanisms for tumor cell kill. As such, trastuzumab may suitably be combined with immunotherapy as a strategy to harness the host's immune system against HER2-positive tumor cells.There is mounting evidence that natural killer (NK) cells have powerful anti-cancer activity. In patients with leukemia undergoing allogeneic hematopoietic stem cell transplant, several studies have demonstrated NK-mediated anti-leukemic activity. Allogeneic NK cell infusions in patients with primary refractory or multiple-relapsed leukemia have been shown to be well tolerated and void of graft-versus-host disease (GVHD) effects. In this study, we seek to enhance the antitumor activity of a commonly used antibody to treat HER2+ breast and gastric cancer, trastuzumab, administered in combination with infusion of activated and expanded autologous NK cells.This is a lead-in phase I followed by a phase II study. Up to 9 patients will be enrolled in phase I to test two different doses of NK cells to be infused into the patient. This will then be followed by a phase II study where 20 patients will be enrolled. Eligible patients will undergo apheresis about 9 days (up to 11 days) prior to cycle 1 therapy to harvest NK cells. The collected NK cells will be expanded and activated ex vivo. On day 1 of cycle 1, the patient will receive herceptin and subcutaneous IL2, followed by NK cell infusion on day 2 of cycle 1. This will then be followed by 5 doses of s/c IL2 three times a week to keep the NK cells activated in vivo. The patient will then receive three more cycles of herceptin (every 21 days). In patients who achieve objective tumor response after cycle 2 or cycle 4, a second NK cell infusion along with s/c IL2 will be administered with cycle 4 or cycle 6 herceptin respectively.This study will determine the safety and efficacy of this novel therapeutic strategy in HER2 positive breast and gastric cancer. It will also provide valuable insights of the role of NK cell infusions in adult solid tumors.