Marie Christine Wulff Westergaard

CCL22-specific T Cells: Modulating the immunosuppressive tumor microenvironment

ABSTRACT Tumor cells and tumor-infiltrating macrophages produce the chemokine CCL22, which attracts regulatory T cells (Tregs) into the tumor microenvironment, decreasing anticancer immunity. Here, we investigated the possibility of targeting CCL22-expressing cells by activating specific T cells. We analyzed the CCL22 protein signal sequence, identifying a human leukocyte antigen A2- (HLA-A2-) restricted peptide epitope, which we then used to stimulate peripheral blood mononuclear cells (PMBCs) to expand populations of CCL22-specific T cells in vitro. T cells recognizing an epitope derived from the signal-peptide of CCL22 will recognize CCL22-expressing cells even though CCL22 is secreted out of the cell. CCL22-specific T cells recognized and killed CCL22-expressing cancer cells. Furthermore, CCL22-specific T cells lysed acute monocytic leukemia cells in a CCL22 expression-dependent manner. Using the Enzyme-Linked ImmunoSPOT assay, we examined peripheral blood mononuclear cells from HLA-A2+ cancer patients and healthy volunteers for reactivity against the CCL22-derived T-cell epitope. This revealed spontaneous T-cell responses against the CCL22-derived epitope in cancer patients and in healthy donors. Finally, we performed tetramer enrichment/depletion experiments to examine the impact of HLA-A2-restricted CCL22-specific T cells on CCL22 levels among PMBCs. The addition or activation of CCL22-specific T cells decreased the CCL22 level in the microenvironment. Activating CCL22-specific T cells (e.g., by vaccination) may directly target cancer cells and tumor-associated macrophages, thereby modulating Treg recruitment into the tumor environment and augmenting anticancer immunity.

Tumor infiltrating lymphocyte therapy for ovarian cancer and renal cell carcinoma.

Personalized cancer immunotherapy based on infusion of T cells holds the promise to specifically target a patient’s individual tumor. Accumulating evidence indicates that the T cells mediating these tumor regressions after cancer immunotherapies may primarily target patient-specific mutations expressed by the patients’ tumors and that the presence of these “neo-antigen” specific T-cells may be related to a high number of mutations in the tumor. In melanoma, treatment with autologous tumor-infiltrating lymphocytes (TILs) can mediate durable complete responses. Previous trials investigating TIL therapy in solid tumors other than melanoma have shown limited success, however none of these early trials used current preparative chemotherapy regimens, and the methods for in vitro lymphocyte expansion have changed considerably. New advances and understandings in T cell based immunotherapies have stimulated the interest in developing this approach for other indications. Here, we summarize the early clinical data in the field of adoptive cell transfer therapy (ACT) using tumor-infiltrating lymphocytes for patients with renal cell carcinoma (RCC) and ovarian cancer (OC). In addition we describe the major advances in the characterization and application of TIL therapy for patients with RCC and OC.

PD-1+ polyfunctional T cells dominate the periphery after tumor-infiltrating lymphocyte therapy for cancer

Purpose: Infusion of highly heterogeneous populations of autologous tumor-infiltrating lymphocytes (TIL) can result in tumor regression of exceptional duration. Initial tumor regression has been associated with persistence of tumor-specific TILs 1 month after infusion, but mechanisms leading to long-lived memory responses are currently unknown. Here, we studied the dynamics of bulk tumor-reactive CD8+ T-cell populations in patients with metastatic melanoma following treatment with TILs. Experimental Design: We analyzed the function and phenotype of tumor-reactive CD8+ T cells contained in serial blood samples of 16 patients treated with TILs. Results: Polyfunctional tumor-reactive CD8+ T cells accumulated over time in the peripheral lymphocyte pool. Combinatorial analysis of multiple surface markers (CD57, CD27, CD45RO, PD-1, and LAG-3) showed a unique differentiation pattern of polyfunctional tumor-reactive CD8+ T cells, with highly specific PD-1 upregulation early after infusion. The differentiation and functional status appeared largely stable for up to 1 year after infusion. Despite some degree of clonal diversification occurring in vivo within the bulk tumor-reactive CD8+ T cells, further analyses showed that CD8+ T cells specific for defined tumor antigens had similar differentiation status. Conclusions: We demonstrated that tumor-reactive CD8+ T-cell subsets that persist after TIL therapy are mostly polyfunctional, display a stable partially differentiated phenotype, and express high levels of PD-1. These partially differentiated PD-1+ polyfunctional TILs have a high capacity for persistence and may be susceptible to PD-L1/PD-L2–mediated inhibition. Clin Cancer Res; 23(19); 5779–88. ©2017 AACR.

T cell responses in the microenvironment of primary renal cell carcinoma - Implications for adoptive cell therapy

TILs isolated from primary RCC specimens could recognize tumors. However, their immune responses were weaker than TILs from metastatic melanoma and displayed a mono-/oligo-functional pattern. The ability to select and expand poly-functional T cells may improve cell therapy for RCC. In vitro expansion of large numbers of highly potent tumor-reactive T cells appears a prerequisite for effective adoptive cell therapy (ACT) with autologous tumor-infiltrating lymphocytes (TIL) as shown in metastatic melanoma (MM). We therefore sought to determine whether renal cell carcinomas (RCC) are infiltrated with tumor-reactive T cells that could be efficiently employed for adoptive transfer immunotherapy. TILs and autologous tumor cell lines (TCL) were successfully generated from 22 (92%) and 17 (77%) of 24 consecutive primary RCC specimens and compared with those generated from metastatic melanoma. Immune recognition of autologous TCLs or fresh tumor digests was observed in CD8+ TILs from 82% of patients (18/22). Cytotoxicity assays confirmed the tumoricidal capacity of RCC-TILs. The overall expansion capacity of RCC-TILs was similar to MM-TILs. However, the magnitude, polyfunctionality, and ability to expand in classical expansion protocols of CD8+ T-cell responses was lower compared with MM-TILs. The RCC-TILs that did react to the tumor were functional, and antigen presentation and processing of RCC tumors was similar to MM-TILs. Direct recognition of tumors with cytokine-induced overexpression of human leukocyte antigen class II was observed from CD4+ T cells (6/12; 50%). Thus, TILs from primary RCC specimens could be isolated, expanded, and could recognize tumors. However, immune responses of expanded CD8+ RCC-TILs were typically weaker than MM-TILs and displayed a mono-/oligofunctional pattern. The ability to select, enrich, and expand tumor-reactive polyfunctional T cells may be critical in developing effective ACT with TILs for RCC. In summary, TILs isolated from primary RCC specimens could recognize tumors. However, their immune responses were weaker than MM-TILs and displayed a mono-/oligofunctional pattern. The ability to select and expand polyfunctional T cells may improve cell therapy for RCC. Cancer Immunol Res; 6(2); 222–35. ©2018 AACR.

T cells isolated from patients with checkpoint inhibitor-resistant melanoma are functional and can mediate tumor regression

Background Almost half of the patients with metastatic melanoma obtain only short-term or no benefit at all from checkpoint inhibitor (CPI) immunotherapy. In this study, we investigated whether the immune system of patients progressing following CPI treatment was able to generate functional tumor-specific immune responses. Materials and methods Tumor-infiltrating lymphocytes (TILs) were isolated and expanded from metastatic melanoma lesions which progressed during or after anti-programmed cell death protein 1 (PD)-1 and anti-Cytotoxic T-Lymphocyte Antigen 4 (CTLA-4) treatment. Tumor-specific immune responses were assessed with co-culture assays of TILs and autologous tumor cells. Results TILs from 23 metastases of individual patients could be assessed for T cells recognition of autologous tumor cells. All metastases were progressive on or following anti-PD-1 (23/23, 100%), and the majority also after anti-CTLA-4 (17/23, 74%). Functional antitumor immune responses were detected in 19/23 patients (83%). Both CD8+ (in 18/23 patients, 78%) and CD4+ (in 16/23 patients, 70%) TILs were able to recognize autologous tumors. A large fraction of CD8+ TILs (median 23%, range 1.0%-84%) recognized tumor cells. This is similar to the cohorts of unselected patient populations with metastatic melanoma presented in previous studies. The localization of intratumoral immune infiltrates was heterogeneous among samples. In a phase I/II clinical trial, TILs were administered with lymphodepleting chemotherapy, pegIFNα2b and interleukin-2 to 12 patients with CPI-resistant melanoma. Out of 12 patients who previously failed CPI therapy, treatment with TILs resulted in two partial responses, of which one is ongoing. Conclusions Tumor-reactive T cells appear to heavily infiltrate the tumor microenvironment of patients who failed previous CPI treatment. These patients can still respond to an infusion of unselected autologous TILs. Our results warrant further testing of novel immune re-activation strategies in melanoma patients who failed multiple CPI therapy.

Polyfunctional incompletely differentiated CD8+ T cells accumulates after adoptive transfer of tumor-infiltrating lymphocytes and establish immunological memory in patients with metastatic melanoma

Infusion of highly heterogeneous populations of autologous tumor-infiltrating lymphocytes (TILs) can result in tumor regression of exceptional duration. Initial tumor regression has been associated to persistence of TILs shortly after infusion, but it is currently not clear whether a single infusion of TILs can establish long term memory antitumor responses.