Functional T cell responses to tumor antigens in breast cancer patients have a distinct phenotype and cytokine signature.

The overall prevalence with which endogenous tumor Ags induce host T cell responses is unclear. Even when such responses are detected, they do not usually result in spontaneous remission of the cancer. We hypothesized that this might be associated with a predominant phenotype and/or cytokine profile of tumor-specific responses that is different from protective T cell responses to other chronic Ags, such as CMV. We detected significant T cell responses to CEA, HER-2/neu, and/or MAGE-A3 in 17 of 21 breast cancer patients naive to immunotherapy. The pattern of T cell cytokines produced in response to tumor-associated Ags (TAAs) in breast cancer patients was significantly different from that produced in response to CMV or influenza in the same patients. Specifically, there was a higher proportion of IL-2-producing CD8(+) T cells, and a lower proportion of IFN-gamma-producing CD4(+) and/or CD8(+) T cells responding to TAAs compared with CMV or influenza Ags. Finally, the phenotype of TAA-responsive CD8(+) T cells in breast cancer patients was almost completely CD28(+)CD45RA(-) (memory phenotype). CMV-responsive CD8(+) T cells in the same patients were broadly distributed among phenotypes, and contained a high proportion of terminal effector cells (CD27(-)CD28(-)CD45RA(+)) that were absent in the TAA responses. Taken together, these results suggest that TAA-responsive T cells are induced in breast cancer patients, but those T cells are phenotypically and functionally different from CMV- or influenza-responsive T cells. Immunotherapies directed against TAAs may need to alter these T cell signatures to be effective.

Modeling individual variation in biomarker response to combination immunosuppression with stimulated lymphocyte responses-potential clinical implications.

BACKGROUND: In mitogen-stimulated lymphocyte responses (sLR), cytokines and cell-surface receptors in peripheral human blood lymphocytes (PBL) are sensitive to cyclosporine (CsA), and can predict its in vivo effect with pharmacodynamic (PD) modeling. This is not known for multiple-agent combinations. METHODS: Twenty-five concentration mixtures of CsA (0-1200 ng/ml) plus sirolimus (SRL, 0-30 ng/ml) were added to whole blood from five normal human subjects (NHS) for effect on a limited array of six targets. Effect-concentration relationships were analyzed with E(max) PD equations, and expressed as the range of concentration mixtures associated with one-half of maximal inhibitory effect (EC(50)) on a model biomarker target. This predicted range was examined to see whether it contained representative concentration mixtures of these two drugs, which were associated with a stable post-transplant outcome in a logistic regression model of 1039 clinical trial patients. RESULTS: PD analyses suggested that in NHS samples containing CsA+SRL (n=5), (1) PMA-Ionomycin-stimulated T-cell expression of intracellular IL-2, TNF-alpha, and IFN-gamma was inhibited by CsA, and minimally by SRL, and (2) the two agents inhibited pokeweed mitogen (PWM)-stimulated B-cell expression of CD54 and CD95, but not CD86 (ICAM-1, Fas antigen, and B7.2), synergistically. With CD54 as the model biomarker, contour plots also predicted a wide range of concentration mixtures of the two agents across which an EC(50) could be predicted for CsA+SRL in a population (e.g., CsA-72 ng/ml+SRL 15 ng/ml, n=5), as well as in the individual subject (e.g., CsA-0 ng/ml+SRL-13.75 ng/ml in NHS-D310). Logistic regression analysis of clinical outcomes in 1039 patients suggested that the concentration mixture of CsA congruent with 50-150 ng/ml+SRL congruent with 10 ng/ml was associated with a stable post-transplant course. The EC(50) contour plot for CD54 suggested a nearly identical CsA concentration of 120 ng/ml in the presence of 10 ng/ml of sirolimus. CONCLUSIONS: Our data suggest that pharmacodynamic evaluation of immunosuppressive agents with biomarkers may be an efficient process with which to characterize immunosuppressive effect of combination agents in individual patients and in patient populations.