Trifunctional antibodies induce efficient antitumour activity with immune cells from head and neck squamous cell carcinoma patients after radio-chemotherapy treatment.

BACKGROUND Trifunctional antibodies, such as catumaxomab (anti-EpCAM×anti-CD3) and ertumaxomab (anti- HER-2/neu×anti-CD3), transiently link immune effector cells to tumour cells, which results in cellular cytotoxicity towards the tumour cells. A functional immune system is therefore essential for effective anti-tumour activity. However, the commonly observed haematotoxicity of chemotherapeutics and radiation therapy may be associated with some degree of immunosuppression. Combining chemotherapy and trifunctional antibodies in cancer treatment requires understanding of the impact of chemotherapeutics on immune cell function and, thus, on the activity of trifunctional antibodies. METHODS The effect of chemotherapeutic treatment on trifunctional antibody-mediated anti-tumour activity was assessed in vitro. Blood samples were collected from 12 head and neck squamous cell carcinoma patients after chemotherapy (5-fluorouracil, cisplatin) and radiotherapy, and from one healthy control donor. The immune cell status was analysed and mononuclear cells (MNC) were isolated. The potency of catumaxomab and ertumaxomab was assessed in a cytotoxicity assay using MNC isolated from each patient sample in co-culture with a tumour target cell line. The release of infl ammatory cytokines was also monitored in the cell culture supernatant. RESULTS Most patients included in this study had decreased immune cell counts during the course of chemotherapy. Nonetheless, an effective and concentration-dependent anti- tumour activity mediated by trifunctional antibodies was demonstrated using these patient immune effector cells. The immune response activity of the patient immune cells was not impaired one week after cisplatin administration or even three days after the last 5-fluorouracil treatment. CONCLUSION This study shows for the first time that immune effector cells from cancer patients undergoing standard chemotherapy and radiotherapy can be activated by trifunctional antibodies for efficient killing of tumour cells.