Redirecting the immune response: role of adoptive T cell therapy

Combination of sorafenib and cytokine-induced killer cells in metastatic renal cell carcinoma: a potential regimen

Metastatic renal cell carcinoma (MRCC) exhibits primary resistance to both chemotherapy and radiotherapy. As an immunogenic cancer, MRCC is relatively sensitive to immunotherapy such as that with cytokines, immune checkpoint inhibitors and adoptive T-cell therapy. In addition, many targeted agents developed over the past decade exhibit greater efficacy than cytokines and have become the standard first-line therapy for MRCC. Several preclinical studies have shown that the targeted agent sorafenib possesses an immunomodulation function and may be suitable for combination with immunotherapy. Here, combinatorial therapy consisting of sorafenib and cytokine-induced killer cell immunotherapy was administered to an MRCC patient resulting in a synergistic effect without serious adverse effects. These results suggest a potential combinatorial regimen for MRCC patients.

Serial low doses of sorafenib enhance therapeutic efficacy of adoptive T cell therapy in a murine model by improving tumor microenvironment

Requirements of large numbers of transferred T cells and various immunosuppressive factors and cells in the tumor microenvironment limit the applications of adoptive T cells therapy (ACT) in clinic. Accumulating evidences show that chemotherapeutic drugs could act as immune supportive instead of immunosuppressive agents when proper dosage is used, and combined with immunotherapy often results in better treatment outcomes than monotherapy. Controversial immunomodulation effects of sorafenib, a multi-kinases inhibitor, at high and low doses have been reported in several types of cancer. However, what is the range of the low-dose sorafenib will influence the host immunity and responses of ACT is still ambiguous. Here we used a well-established E.G7/OT-1 murine model to understand the effects of serial low doses of sorafenib on both tumor microenvironment and transferred CD8+ T cells and the underlying mechanisms. Sorafenib lowered the expressions of immunosuppressive factors, and enhanced functions and migrations of transferred CD8+ T cells through inhibition of STAT3 and other immunosuppressive factors. CD8+ T cells were transduced with granzyme B promoter for driving imaging reporters to visualize the activation and distribution of transferred CD8+ T cells prior to adoptive transfer. Better activations of CD8+ T cells and tumor inhibitions were found in the combinational group compared with CD8+ T cells or sorafenib alone groups. Not only immunosuppressive factors but myeloid derived suppressive cells (MDSCs) and regulatory T cells (Tregs) were decreased in sorafenib-treated group, indicating that augmentation of tumor inhibition and function of CD8+ T cells by serial low doses of sorafenib were via reversing the immunosuppressive microenvironment. These results revealed that the tumor inhibitions of sorafenib not only through eradicating tumor cells but modifying tumor microenvironment, which helps outcomes of ACT significantly.

Exploiting differential expression of the IL-7 receptor on memory T cells to modulate immune responses

Interleukin-7 is a non-redundant growth, differentiation and survival factor for human T lymphocytes. Most circulating, mature T cells express the receptor for IL-7, but not all. Importantly, CD4 Tregs express greatly reduced levels of IL-7R compared to conventional CD4 T cells, presenting an opportunity to selectively target the latter cells with either more IL-7 to boost responses, or to block IL-7 signalling to limit responses. This article reviews what is known about regulation of IL-7R expression, and recent progress in therapeutic approaches related to IL-7 and its receptor.

Expression of leukotriene B₄ receptor-1 on CD8⁺ T cells is required for their migration into tumors to elicit effective antitumor immunity

Leukotriene B₄ (LTB₄) receptor (BLT)1 is expressed on variety of immune cells and has been implicated as a mediator of diverse inflammatory diseases. However, whether biological responses initiated via this receptor generate tumor-promoting inflammation or antitumor immunity remains unexplored. In this study, we investigated the role of BLT1 in antitumor immunity using syngeneic TC-1 cervical cancer model, and observed accelerated tumor growth and reduced survival in BLT1⁻/⁻ mice compared with BLT1⁺/⁺ mice. Analysis of the tumor infiltrates by flow cytometry and confocal microscopy revealed a significant decrease in effector immune cells, most notably, CD8⁺ T cells and NK cells in the tumors of the BLT1⁻/⁻ mice. Gene expression profiling confirmed the dramatic decrease of IFN-γ, granzyme B, and IL-2 in tumors growing in BLT1⁻/⁻ mice. Furthermore, depletion of CD8⁺ T cells enhanced the tumor growth in BLT1⁺/⁺ but not in BLT1⁻/⁻ mice. However, similar levels of Ag-dependent CD8⁺ T cell-mediated killing activity were observed in spleens of BLT1⁺/⁺ and BLT1⁻/⁻ mice. Adoptive transfer of CD8⁺ T cells from tumor-bearing BLT1⁺/⁺ but not BLT1⁻/⁻ mice significantly reduced tumor growth and increased the survival of Rag2⁻/⁻ mice. Although the homeostatic proliferation and expression profiles of other chemokine receptors of adoptively transferred BLT1⁺/⁺ and BLT1⁻/⁻ CD8⁺ T cells appears to be similar, BLT1⁺/⁺ T lymphocytes entered the tumors in greater numbers. These results suggest that BLT1 expression on CD8⁺ T cells plays an important role in their trafficking to tumors.

Adoptive T-cell transfer in melanoma

Immunotherapy holds a highly promising treatment approach for metastatic melanoma patients. Adoptive cell transfer (ACT) involves the ex vivo expansion of autologous antitumor reactive lymphocytes and their reinfusion into lymphodepleted patients, accompanied by IL-2 administration. ACT with tumor-infiltrating T lymphocytes demonstrates objective clinical responses in 50-72% of the patients, including 10-40% complete responses and was shown to produce durable disease control with long progression-free survival. Tumor-infiltrating T-lymphocyte ACT might even have curative potential as the vast majority of the complete responders are without any evidence of disease many years after treatment. Other adoptive transfer studies employ the genetic modification of T lymphocytes with genes encoding tumor-specific T cell receptors or antibody-based chimeric antigen receptors. These approaches opened numerous possibilities to treat cancers other than melanoma. In this article we will summarize the ACT strategies in melanoma, the new developments in this field and combinations with other therapies.

Lactobacillus acidophilus could modulate the immune response against breast cancer in murine model

Cancer immune-therapy is an interesting avenue of studying the effects of deviating immune system responses to achieve the desired result. Lactobacilli are inhabitants of the GI tract which have shown beneficial health effects on various ailments including malignancies. Their mechanisms of action comprise a very intense area of research. In this study we evaluated the immunomodulatory effects of Lactobacillus acidophilus in in vivo model of breast cancer. Lactobacillus acidophilus (L.a) was isolated from traditional home-made yogurt and also from neonatal stool by aerobic overnight culture at 37°C in MRS broth. Delayed Type Hypersensitivity (DTH) assay was performed to find the best immunostimulant dose. 4T1 tumour bearing mice were treated with 2 × 10(8) cfu of isolated L. acidophilus and 20 mg/kg Cyclophosphamide for 15 consecutive days. Tumour volume was measured using a digital vernier calliper. Lymphocyte proliferation was done using MTT proliferation assay. Production of IFNγ, IL-4 and TGF-β from cultured Splenocytes was assessed in the presence of purified tumour antigen. According to results administration of L.a induced a significant decrease in tumour growth pattern (P value = 0.00). Significant alterations in splenocyte production of IFN-γ, IL-4 and TGf-β (P values < 0.05) and also lymphocyte proliferation in L.a treated animals was evident (P value < 0.05). This study indicated that oral administration of L.a is able to alter the cytokine production in tumour bearing mice into a Th1 protective pattern, favourable to anti tumour immunity. Reduced tumour growth rate and increased lymphocyte proliferation are also thus supportive. Further studies are required to elucidate the exact mechanism by which local actions of probiotics affect the systemic immune responses against transformed cells.