MHC class I restricted and antigen-specific TCRs against viral and tumor-associated antigens (TAAs) for future biological therapy

Abstract

Adoptive cellular immunotherapy (ACT) refers to the process of transferring immune cells (autologous or allogeneic) directly to the host as a treatment for cancer or infectious diseases. The effector cells could be antigen-specific, like T cells, or non-specific, such as NK cells or lymphokine-activated killer (LAK) cells. A substantial amount of evidence shows that T cells play an important role in controlling pathogens and tumor growth. Controlling pathogens and orchestrating the function of immune cells depends on engagement of the nominal TCR (T-cell receptor) with its ligand (the MHC class I or -II peptide complex), the structure and function of T cell receptor (TCR) and the subsequent immune effector functions upon TCR triggering (cytotoxicity, proliferation, cytokine production).

Tumor-infiltrating T-cells (TILs) represent a source of T-cells for the immunotherapy of patients with tumors of the central nervous system and pancreas. According to the results of paper I and II, we successfully established a rapid TIL expansion protocol for patients with brain tumors or pancreatic cancer. TILs were shown to produce Th1-cytokines and were able to recognize autologous tumor cells defined by cytokine production or cytoxicity.

In paper III, we found that tumor associated antigens (TAAs)-reactive T-cells could be successfully expanded from patients with glioma with IL-2, IL-15 and IL-21; they exhibit a Th1 cytokine pattern and a central memory phenotype. NY-ESO-1 expression was found in 15/38 cases and survivin expression in 20/40 cases in glioblastoma, defined by immunohisto-chemistry. Thus, NY-ESO-1 or survivin represent a potential target for anti-NY-ESO-1 or anti-survivin directed T-cells for the biological therapy of patients with glioblastoma (GBM).

Mesothelin was first identified to be overexpressed in ovarian cancer. It is constitutively expressed in normal tissue, e.g. pericardium, pleura or peritoneum. This 40kDa protein could serve as a tumor marker and as a target of immunotherapy for anti-cancer directed T-cells. In paper IV, mesothelin was found to be expressed in 4 out of 11 GBM tissues, by immune-fluorescence staining. Mesothelin directed T cell reactions were also observed in a whole blood assay (WBA) measured in 293 patients with brain tumors. Mesothelin immunogenic epitopes were also identified using a peptide mapping assay; mesothelin-specific TILs could be expanded from glioma samples.

We analyzed in detail potential prospective factors in patients with GBM (n=145) and non-GBM (n=60) which refers to glioma (WHO grade II or III). In paper V, we performed univariate Kaplan-Meier (K-M) survival analysis by setting of groups based on demographic, clinical, immunological parameters and immunological reactivity patterns, then we defined factor(s) with a cut-off strategy. We performed further multivariate analysis with a Cox proportional hazards model (forward and backward stepwise analysis) to determine the key factor related with patient’s survival by considering (and omitting) interactions between employed factors. We found that T-cell reactivity to an individual survivin epitope (97-111) is positively related (P=0.024) with survival of patients with GBM. The same was found to be true for the serum cytokine pattern of IL-4/IL-5/IL-6 (P=0.052) and IFN-γ/TNF-α/IL-17A (P=0.003) which could serve as ‘predictor’ for prognosis in clinical settings. The cytokine serum profile as well as the immune reactivity to survivin may serve as a clinically relevant indicator for the clinical follow up of patients with GBM after surgery and provide a viable option to offer tailored immunological therapy.