Detection of ABCB5 tumour antigen-specific CD8+ T cells in melanoma patients and implications for immunotherapy

CAR-T therapy: Prospects in targeting cancer stem cells

Cancer stem cells (CSCs), a group of tumour cells with stem cell characteristics, have the ability of self-renewal, multi-lineage differentiation and tumour formation. Since CSCs are resistant to conventional radiotherapy and chemotherapy, their existence may be one of the root causes of cancer treatment failure and tumour progression. The elimination of CSCs may be effective for eventual tumour eradication. Because of the good therapeutic effects without major histocompatibility complex (MHC) restriction and the unique characteristics of CSCs, chimeric antigen receptor T-cell (CAR-T) therapy is expected to be an important method to eliminate CSCs. In this review, we have discussed the feasibility of CSCs-targeted CAR-T therapy for cancer treatment, summarized current research and clinical trials of targeting CSCs with CAR-T cells and forecasted the challenges and future direction from the perspectives of toxicity, persistence and potency, trafficking, infiltration, immunosuppressive tumour microenvironment, and tumour heterogeneity.

Combining photothermal therapy and immunotherapy against melanoma by polydopamine-coated Al2O3 nanoparticles

Photothermal therapy (PTT) can be an effective antitumor therapy, but it may not completely eliminate tumor cells, leading to the risk of recurrence or metastasis. Here we describe nanocarriers that allow combination therapy involving PTT and immunotherapy. Nanocarriers are prepared by coating Al₂O₃ nanoparticles with non-toxic, biodegradable polydopamine, which shows high photothermal efficiency. A near-infrared laser irradiation can kill the majority of tumor tissues, resulting in the release of tumor-associated antigens. The Al₂O₃ within the nanoparticles, together with CpG, acts as an adjuvant to trigger robust cell-mediated immune responses that can help eliminate the residual tumor cells and reduce the risk of tumor recurrence.

Methods: The characteristics and photothermal performance of polydopamine-coated Al₂O₃ nanoparticles were examined after one-step preparation. Then we studied their internalization, photothermal toxicity and immunostimulatory activity in vitro. For in vivo experiments, these nanocarriers were injected directly into B16F10 melanoma allografts in mice to ensure specific localization. After photothermal irradiation on day 0, mice were subcutaneously injected with CpG adjuvant on day 1, 3 and 5. Tumor volumes and number of living mice were recorded every two days. Moreover, various immune responses induced by our combined therapy were tested for mechanism research.

Results: 50% of mice after our combined treatment successfully achieved the goal of tumor eradication, and survived for 120 days, which was the end point of the experiment. Mechanism studies demonstrated the combined therapy efficiently led to dendritic cell maturation, resulting in the secretion of antibodies and cytokines as well as the proliferation of splenocytes and lymphocytes for anti-tumor immunotherapy.

Conclusion: Taken together, these results demonstrated the promise of our combined photothermal therapy and immunotherapy for tumor shrinkage, which merited further research.

Frequent adaptive immune responses against arginase-1

The enzyme arginase-1 reduces the availability of arginine to tumor-infiltrating immune cells, thus reducing T-cell functionality in the tumor milieu. Arginase-1 is expressed by some cancer cells and by immune inhibitory cells, such as myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs), and its expression is associated with poor prognosis. In the present study, we divided the arginase-1 protein sequence into overlapping 20-amino-acid-long peptides, generating a library of 31 peptides covering the whole arginase-1 sequence. Reactivity towards this peptide library was examined in PBMCs from cancer patients and healthy individuals. IFNγ ELISPOT revealed frequent immune responses against multiple arginase-1-derived peptides. We further identified a hot-spot region within the arginase-1 protein sequence containing multiple epitopes recognized by T cells. Next, we examined in vitro-expanded tumor-infiltrating lymphocytes (TILs) isolated from melanoma patients, and detected arginase-1-specific T cells that reacted against epitopes from the hot-spot region. Arginase-1-specific CD4+T cells could be isolated and expanded from peripheral T cell pool of a patient with melanoma, and further demonstrated the specificity and reactivity of these T cells. Overall, we showed that arginase-1-specific T cells were capable of recognizing arginase-1-expressing cells. The activation of arginase-1-specific T cells by vaccination is an attractive approach to target arginase-1-expressing malignant cells and inhibitory immune cells. In the clinical setting, the induction of arginase-1-specific immune responses could induce or increase Th1 inflammation at the sites of tumors that are otherwise excluded due to infiltration with MDSCs and TAMs.

Advances in Proteomic Techniques for Cytokine Analysis: Focus on Melanoma Research

Melanoma is a skin cancer with permanently increasing incidence and resistance to therapies in advanced stages. Reports of spontaneous regression and tumour infiltration with T-lymphocytes makes melanoma candidate for immunotherapies. Cytokines are key factors regulating immune response and intercellular communication in tumour microenvironment. Cytokines may be used in therapy of melanoma to modulate immune response. Cytokines also possess diagnostic and prognostic potential and cytokine production may reflect effects of immunotherapies. The purpose of this review is to give an overview of recent advances in proteomic techniques for the detection and quantification of cytokines in melanoma research. Approaches covered span from mass spectrometry to immunoassays for single molecule detection (ELISA, western blot), multiplex assays (chemiluminescent, bead-based (Luminex) and planar antibody arrays), ultrasensitive techniques (Singulex, Simoa, immuno-PCR, proximity ligation/extension assay, immunomagnetic reduction assay), to analyses of single cells producing cytokines (ELISpot, flow cytometry, mass cytometry and emerging techniques for single cell secretomics). Although this review is focused mainly on cancer and particularly melanoma, the discussed techniques are in general applicable to broad research field of biology and medicine, including stem cells, development, aging, immunology and intercellular communication.