Induction of anti-tumor immunity by trifunctional antibodies in patients with peritoneal carcinomatosis

Abstract

Peritoneal carcinomatosis (PC) from epithelial tumors is a fatal diagnosis without efficient treatment. Trifunctional antibodies (trAb) are novel therapeutic approaches leading to a concerted anti-tumor activity resulting in tumor cell destruction. In addition, preclinical data in mouse tumor models demonstrated the induction of long lasting tumor immunity after treatment with trAb. We describe the induction of anti-tumor specific T-lymphocytes after intraperitoneal administration of trAb in patients with PC.9 patients with progressive PC from gastric (n = 6) and ovarian cancer (n = 2), and cancer of unknown primary (n = 1) received 3 escalating doses of trAb after surgery and/or ineffective chemotherapy. The trAb EpCAM x CD3 (10, 20, 40 microg) or HER2/neu x CD3 (10, 40, 80 microg) were applicated by intraperitoneal infusion. Four weeks after the last trAb application, all patients were restimulated by subdermal injection of trAb + autologous PBMC + irradiated autologous tumor cells. Immunological reactivity was tested by analyzing PBMC for specific tumor reactive CD4+/CD8+ T lymphocytes using an IFN-gamma secretion assay.In 5 of 9 patients, tumor reactive CD4+/CD8+ T-lymphocytes increased significantly, indicating specific anti-tumor immunity. A clinical response (stable disease, partial regression) has been observed in 5 of 9 patients, with a mean time to progression of 3.6 months. Follow-up showed a mean survival of 11.8 months (median 8.0 months) after trAb therapy.TrAb are able to induce anti-tumor immunity after intraperitoneal application and restimulation. The induction of long-lasting anti-tumor immunity may provide an additional benefit of the intraperitoneal therapy with trAb and should be further elevated in larger clinical trials.

Figure 1

Serum levels (mean, +/- SEM) of TNF-α (A), soluble IL-2R (B), and IL-6 (C) immediately before the first, second and third trAb application, and corresponding serum levels on day one and two dafter trAb therapy. Serum levels were measured by ELISA (Biosource, Fleurs, Belgium). * p < 0.05.

Figure 2

Individual percentage values presenting the relative proportion of IFN-γ secreting T-lymphocytes in 10 × 10⁶ PBMC after stimulation with 5 × 10⁵ autologous tumor cells before and 3–4 weeks after trAb therapy using the Miltenyi IFN-γ secretion assay.

Figure 3

Analysis of tumor reactive IFN-γ secreting CD4+/CD8+ T lymphocytes before trAb therapy and on day 39 and 110 after boost stimulation in patient B using the Miltenyi IFN-γ secretion assay.