Immune therapies in patients with metastatic malignant melanoma consisting of tumor infiltrating lymphocytes and interleukin-2 have resulted in significant clinical regressions. Understanding the interactions between lymphocytes and tumors in-vitro is critical for the further development of these therapies for patients. We have recently began similar studies in patients with metastatic breast carcinoma after previously identifying specific cytokine secretion by lymphocytes infiltrating breast cancers when stimulated with their autologous tumors. The following areas are under current study. l. Screening of breast cancer infiltrating lymphocytes. We initially discovered that lymphocytes derived from 3 of 11 breast carcinomas specifically secreted GM-CSF, TNF-alpha, and IFN-gamma in response to autologous tumor stimulation. Subsequently we have screened nineteen breast cancer lymphocyte cultures and have identified two that specifically secrete cytokines in an MHC class II restricted fashion. We are attempting to grow breast cancer tumor lines from these patients mice, since culturing of these tumors has been nearly impossible. If these reagents can be successfully established, they could be used for identification of a breast tumor antigen. This finding would have great potential value in developing vaccines and other immunotherapies. 2. In vitro predictors of clinical response. An extensive study of in vitro characteristics of lymphocytes infiltrating human melanomas that were subsequently used to treat patients has been conducted. Forty-three patients have been studied and we have confirmed previous observations that in-vitro cytolysis of autologous tumor is greater in responding than nonresponding patients. This finding has lead us to modify our current clinical studies to treat patients that only have lymphocytes that are lytic in-vitro. Another association with response to therapy has been the finding of greater cytokine secretion by these lymphocytes. 3. Expansion of lymphocytes with briostatin and ionomycin. We explored the possibility of expanding large numbers of lymphocytes from tumors infiltrating breast cancers using the PKC activator briostatin and the calcium ionophore ionomycin. The goal was to expand lymphocytes with specific antitumor reactivity. Lymphocytes from 8 breast cancer specimens did not show increased proliferation over conventional culture techniques and did not recognize autologous tumors in cytolysis or cytokine assays.
