Abstract LB-321: Changing the route of immunization determines outcome in immunotherapy of experimental brain tumors: Translation in development

Abstract

Abstract Introduction: Based on our previous experimental result we have performed a clinical trial at the Lund University Hospital, with immunotherapy using IFN transduced autologous tumor cells for intradermal (i.d.) immunizations in adult patients with glioblastoma multiforme. Eight patients have been treated with an increase in overall survival by more than six months as compared to age-matched controls. The trial has shown that the therapy has no side effects and that an immune activation can be detected. Current experimental results show that by changing the route of immunization from i.d. to sub-cutaneous (s.c.) immunization, a substantial increase in survival time of animals is seen. The mechanisms behind this are now under investigation. Experimental Procedures: We are currently investigating the therapeutic efficacy of i.d. or s.c. administerd IFN transduced irradiated tumor cells (N32-IFNγ) against intra cerebral tumors in the rat glioma model (N32) syngeneic with the Fisher 344 rat. The rats are immunized day 1, 15 and day 29 after tumor inoculation. The induction of the immune response is studied by tracing irradiated CFDA-SE stained tumor cells from the immunization site (i.d. or s.c.) to secondary lymphoid organs using immuno-histochemistry. The immune response is studied at different time-points after the first and after the third immunization. Preliminary Results: S.c. immunization with N32-IFNγ cured 53% of the tumor bearing animals compared to i.d. immunization where only 6% of the rats survived for 100 days, when the study was finalized. After the first immunization, tumor cell debris can be traced to inguinal lymph nodes of i.d. immunized animals, but not of s.c. immunized animals. After the third immunization tumor debris is found in inguinal lymph nodes both after i.d. and s.c. immunization. No other secondary lymphoid tissues tested contain tumor debris. Mononuclear phagocytes expressing MHC class II are responsible for engulfing tumor cells at the immunization site of both i.d. and s.c. immunized animals. Cells that strongly express the enzyme cyclooxygenase-2, the rate-limiting enzyme for production of prostaglandine E2, are seen after s.c. immunization but not after i.d. immunization. Further studies are ongoing to reveal possible differences in kinetics and antigen presenting cells. Conclusions: To our knowledge, no systematic comparison has been performed between different immunization routes using whole tumor cells as immunogen. If these results are further confirmed, the route of immunization will be altered from i.d. to s.c. in future clinical trials. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-321.