Adoptive cell transfer therapy with ex vivo primed peripheral lymphocytes in combination with anti-PDL1 therapy effectively inhibits triple-negative breast cancer growth and metastasis.

BACKGROUND: Adoptive cell transfer cancer immunotherapy holds promise for treating disseminated disease, yet generating sufficient numbers of lymphocytes with anti-cancer activity against diverse specificities remains a major challenge. We recently developed a novel procedure (ALECSAT) for selecting, expanding and maturating polyclonal lymphocytes from peripheral blood with the capacity to target malignant cells. METHODS: Immunodeficient mice were challenged with triple-negative breast cancer cell lines or patient-derived xenografts (PDX) and treated with allogeneic or autologous ALECSAT cells with and without anti-PDL1 therapy to assess the capacity of ALECSAT cells to inhibit primary tumor growth and metastasis. RESULTS: ALECSAT mono therapy inhibited metastasis, but did not inhibit primary tumor growth or prolong survival of tumor-bearing mice. In contrast, combined ALECSAT and anti-PDL1 therapy significantly inhibited primary tumor growth, nearly completely blocked metastasis, and prolonged survival of tumor-bearing mice. CONCLUSIONS: Combined ALECSAT and anti-PDL1 therapy results in favorable anti-cancer responses in both cell line-derived xenograft and autologous PDX models of advanced triple-negative breast cancer.

A randomized phase II trial of efficacy and safety of the immunotherapy ALECSAT as an adjunct to radiotherapy and temozolomide for newly diagnosed glioblastoma.

BACKGROUND: There is an urgent need for effective treatments against glioblastoma (GBM). In this trial, we investigated the efficacy and safety of an adoptive cell-based immunotherapy. METHODS: Patients with newly diagnosed GBM were recruited at 4 study sites in Sweden. The patients were randomized 1:2 to receive either radiotherapy (RT), 60 Gy/30 fractions, with concomitant and adjuvant temozolomide (TMZ) only, or RT and TMZ with the addition of Autologous Lymphoid Effector Cells Specific Against Tumor (ALECSAT) in an open-label phase II trial. The primary endpoint was investigator-assessed progression-free survival (PFS). The secondary endpoints were survival and safety of ALECSAT. RESULTS: Sixty-two patients were randomized to either standard of care (SOC) with RT and TMZ alone (n = 22) or SOC with ALECSAT (n = 40). Median age was 57 years (range 38-69), 95% of the patients were in good performance status (WHO 0-1). There was no significant difference between the study arms (SOC vs ALECSAT + SOC) in PFS (7.9 vs 7.8 months; hazard ratio [HR] 1.28; 95% confidence interval [CI] 0.70-2.36; P = .42) or in median overall survival (OS) (18.3 vs 19.2 months; HR 1.16, 95% CI 0.58-2.31; P = .67). The treatment groups were balanced in terms of serious adverse events (52.4% vs 52.5%), but adverse events ≥grade 3 were more common in the experimental arm (81.0% vs 92.5%). CONCLUSION: Addition of ALECSAT immunotherapy to standard treatment with radiochemotherapy was well tolerated but did not improve PFS or OS for patients with newly diagnosed GBM.

Adoptive cancer immunotherapy using DNA-demethylated T helper cells as antigen-presenting cells.

In cancer cells, cancer/testis (CT) antigens become epigenetically derepressed through DNA demethylation and constitute attractive targets for cancer immunotherapy. Here we report that activated CD4+ T helper cells treated with a DNA-demethylating agent express a broad repertoire of endogenous CT antigens and can be used as antigen-presenting cells to generate autologous cytotoxic T lymphocytes (CTLs) and natural killer cells. In vitro, activated CTLs induce HLA-restricted lysis of tumor cells of different histological types, as well as cells expressing single CT antigens. In a phase 1 trial of 25 patients with recurrent glioblastoma multiforme, cytotoxic lymphocytes homed to the tumor, with tumor regression ongoing in three patients for 14, 22, and 27 months, respectively. No treatment-related adverse effects were observed. This proof-of-principle study shows that tumor-reactive effector cells can be generated ex vivo by exposure to antigens induced by DNA demethylation, providing a novel, minimally invasive therapeutic strategy for treating cancer.

The immunodominant HLA-A2-restricted MART-1 epitope is not presented on the surface of many melanoma cell lines.

Among the relatively large number of known tumor-associated antigens (TAA) which are recognized by human CD8 T-cells, Melan-A/MART-1 is one of the most-if not the most-frequently used target for anti-cancer vaccines in HLA-A2 + melanoma patients. In this study, we analyzed the killing of a large panel of melanoma cells by a high avidity, MART-1-specific T-cell clone or a MART-1-specific, polyclonal T-cell culture. Strikingly, we observed that the MART-1-specific T-cells only killed around half of the analyzed melanoma cell lines. In contrast a Bcl-2-specific T-cell clone killed all melanoma cell lines, although the T-cell avidity of this clone was significantly lower. The MART-1-specific T-cell clone expressed NKG-2D and was fully capable of releasing both perforin and Granzyme B. Notably, the resistance to killing by the MART-1-specific T-cells could be overcome by pulsing of the melanoma cells with the MART-1 epitope. Thus, the very frequently used MART-1 epitope was not expressed on the surface of many melanoma cell lines. Our data emphasize that the selected tumor antigens and/or epitopes are critical for the outcome of anti-cancer immunotherapy.

Detection of circulating tumor lysate-reactive CD4+ T cells in melanoma patients.

PURPOSE: We wanted to study whether an allogeneic melanoma lysate would be a feasible stimulatory antigen source for detection of a peripheral CD4+ T-cell immune response in patients with medically untreated malignant melanoma. The lysate was produced from a melanoma cell line (FM3.29) which expresses high amounts of melanoma antigens. METHODS: Fresh peripheral blood was incubated with and without lysate for 6 h in the presence of anti-CD28/anti-CD49d MoAb (for costimulation). After flow cytometric estimation of the frequency of CD69+/IFN-gamma+ cells in the CD4+ population, the response to lysate was calculated as the difference between the number of activated IFN-gamma-producing CD4+ cells in the lysate-stimulated and the nonstimulated sample. RESULTS: An immune response to lysate was observed in blood samples from 11 of 15 patients (73%) with metastatic melanoma. A weak response was found in 1 of 4 patients radically operated for localized disease, whereas no responders were seen among 7 healthy donors. The fraction of circulating lysate-activated T cells ranged from 0.0037% to 0.080% of the CD4+ population. A negative result of the assay was found occasionally, especially in donors with high background levels of spontaneous IFN-gamma production, indicating an inhibitory effect of the lysate. CONCLUSIONS: This method for detection of a peripheral T-cell immune response in melanoma patients has several advantages for clinical use. The tumor lysate preparations may contain large numbers of stimulating antigens (known, as well as unknown) and are easily prepared and handled. Potentially, the assay might be useful as a diagnostic tool, a marker of residual or recurrent disease, a prognostic factor, or a predictor or monitor of the effect of antineoplastic therapy including immune-modulating therapy.

Cancer/testis antigens: structural and immunobiological properties.

Characterization of tumor-associated antigens recognized by cytotoxic T lymphocytes which has evolved during recent years opens new possibilities for specific anti-cancer immunotherapy. Among different groups of tumor-associated antigens, cancer/testis (CT) antigens (expressed in many tumors and among normal tissues only in testes) represent the most perspective antigens for immunotherapy because of their broad tumor-specific expression. More than 50 CT antigens have been described so far and, for many of them, epitopes recognized by T lymphocytes have been identified. The most studied group of CT antigens is the MAGE proteins, which form the so-called MAGE superfamily, together with some MAGE-like proteins that have a different distribution than classical CT antigens. The MAGE superfamily includes five families: MAGE-A, MAGE-B, MAGE-C, MAGE-D, and necdin. Comparison of the structure of members of MAGE superfamily points to the existence of a domain organization of these proteins. The central, core domain (second domain) is highly conservative. The first domain is homologous among MAGE family members with a CT expression, but unique for each member of the MAGE-D and necdin families. In addition to the homology of the central domain, the third domain is also homologous among all members of MAGE superfamily, but to a much lesser extent. The MAGE-D proteins contain an additional, fourth domain, which in the case of MAGE-D3 coincides with trophinin, a separate molecule described previously as an adhesion molecule that participates in embryo implantation. The structural classification of the members of MAGE superfamily might help in the future to understand the biological function of MAGE proteins. One important property of the CT antigens is the up-regulation of their expression by DNA demethylating agents, indicating a possible mechanism for their re-expression in tumors. One of the implications of this particular property could be that a combination of immunotherapy targeting CT antigens with chemotherapy inducing up-regulation of CT antigens might result in more efficient tumor eradication.