Melanoma is a highly aggressive tumor derived from melanocytes. In recent years, the incidence and mortality of melanoma have gradually increased, seriously threatening human health. Classic ...treatments like surgery, chemotherapy, and radiotherapy show very limited efficacy. Due to the high immunogenicity of melanoma cells, immune checkpoint inhibitors have received considerable attention as melanoma treatments. One such therapy is blockade of programmed cell death‐1 (PD‐1), which is one of the most important negative immune regulators and is mainly expressed on activated T cells. Disruption of the interactions between PD‐1 and its ligands, programmed death‐ligand 1 (PD‐L1) or programmed death‐ligand 2 (PD‐L2) rejuvenates exhausted T cells and enhances antitumor immunity. Although PD‐1 blockade therapy is widely used in melanoma, a substantial proportion of patients still show no response or short durations of remission. Recent researches have focused on revealing the underlying mechanisms for resistance to this treatment and improving its efficacy through combination therapy. Here, we will introduce the resistance mechanisms associated with PD‐1 blockade therapy in melanoma and review the combination therapies available.
Immune checkpoint inhibitors (ICI) such as PD-1/PD-L1 antibodies (Abs) and CTLA4 Abs and T cell-based adoptive cell therapies are effective for patients with various cancers. However, response rates ...of ICI monotherapies are still limited due to lack of immunogenic antigens and various immune-resistant mechanisms. The latter includes adaptive immune resistance that is caused by anti-tumor T cells (e.g. PD-L1 induced by IFN-γ from T cells) and primary immune resistance that is caused by cancer cells (e.g. immunosuppressive cytokines produced by cancer cells). Further understanding of the immune-resistant mechanisms, which may be possible through comparative analyses of responders and non-responders to the immunotherapies, will lead to the identification of new diagnostic biomarkers and therapeutic targets for development of effective cancer immuno therapies.
To improve current cancer immunotherapies, strategies to modulate various immunosuppressive cells including myeloid derived suppressor cells (MDSC) which were shown to be negative factors in ...immune‐checkpoint blockade therapy, need to be developed. In the present study, we evaluated the role of the local renin‐angiotensin system (RAS) in the tumor immune‐microenvironment using murine models bearing tumor cell lines in which RAS was not involved in their proliferation and angiogenetic ability. Giving angiotensin II receptor blockers (ARB) to C57BL/6 mice bearing murine colon cancer cell line MC38 resulted in significant enhancement of tumor antigen gp70 specific T cells. ARB administration did not change the numbers of CD11b+ myeloid cells in tumors, but significantly reduced their T‐cell inhibitory ability along with decreased production of various immunosuppressive factors including interleukin (IL)‐6, IL‐10, vascular endothelial growth factor (VEGF), and arginase by CD11b+ cells in tumors. ARB also decreased expression of immunosuppressive factors such as chemokine ligand 12 and nitric oxide synthase 2 in cancer‐associated fibroblasts (CAF). Last, combination of ARB and anti‐programmed death‐ligand 1 (PD‐L1) antibodies resulted in significant augmentation of anti‐tumor effects in a CD8+ T cell‐dependent way. These results showed that RAS is involved in the generation of an immunosuppressive tumor microenvironment caused by myeloid cells and fibroblasts, other than the previously shown proliferative and angiogenetic properties of cancer cells and macrophages, and that ARB can transform the immunosuppressive properties of MDSC and CAF and could be used in combination with PD‐1/PD‐L1 immune‐checkpoint blockade therapy.
Local renin–angiotensin system is involved in generation of immunosuppressive tumor microenvironment caused by myeloid cells and fibroblasts. Angiotensin receptor blockers can transform the immunosuppressive properties of myeloid derived suppressor cells and cancer‐associated fibroblasts and could be used in combination with PD‐1/PD‐L1 immune checkpoint blockade therapy.
Current xenogeneic mouse models cannot evaluate on-target off-tumor adverse effect, hindering the development of chimeric antigen receptor (CAR) T cell therapies for solid tumors, due to limited ...human/mouse cross-reactivity of antibodies used in CAR and sever graft-versus-host disease induced by administered human T cells. We have evaluated safety and antitumor efficacy of CAR-T cells targeting glypican-1 (GPC1) overexpressed in various solid tumors. GPC1-specific human and murine CAR-T cells generated from our original anti-human/mouse GPC1 antibody showed strong antitumor effects in xenogeneic and syngeneic mouse models, respectively. Importantly, the murine CAR-T cells enhanced endogenous T cell responses against a non-GPC1 tumor antigen through the mechanism of antigen-spreading and showed synergistic antitumor effects with anti-PD-1 antibody without any adverse effects in syngeneic models. Our study shows the potential of GPC1 as a CAR-T cell target for solid tumors and the importance of syngeneic and xenogeneic models for evaluating their safety and efficacy.
Modulation of the immunosuppressive tumor microenvironment (TME) is essential for enhancing the anti‐tumor effects of immune checkpoint inhibitors (ICIs). Adhesion molecules and enzymes such as ...vascular adhesion protein‐1 (VAP‐1), which are expressed in some cancers and tumor vascular endothelial cells, may be involved in the generation of an immunosuppressive TME. In this study, the role of VAP‐1 in TME was investigated in 2 murine colon cancer models and human cancer cells. Intraperitoneal administration of the VAP‐1‐specific inhibitor U‐V296 inhibited murine tumor growth by enhancing IFN‐γ‐producing tumor antigen‐specific CD8+ T cells. U‐V296 exhibited significant synergistic anti‐tumor effects with ICIs. In the TME of mice treated with U‐V296, the expression of genes associated with M2‐like macrophages, Th2 cells (Il4, Retnla, and Irf4), angiogenesis (Pecam1), and fibrosis (Acta2, Loxl2) were significantly decreased, and the Th1/Th2 balance was increased. H2O2, an enzymatic product of VAP‐1, which promoted the production of IL‐4 by mouse Th2 and inhibited IFN‐γ by mouse Th1 and human tumor‐infiltrating lymphocytes, was decreased in tumors and CD31+ tumor vascular endothelial cells in the TMEs of mice treated with VAP‐1 inhibitor. TCGA database analysis showed that VAP‐1 expression was a negative prognostic factor in human cancers, exhibiting a significant positive correlation with IL‐4, IL4R, and IL‐13 expression and a negative correlation with IFN‐γ expression. These results indicated that VAP‐1 is involved in the immunosuppressive TMEs through H2O2‐associated Th2/M2 conditions and may be an attractive target for the development of combination cancer immunotherapy with ICIs.
In this study, we have identified the involvement of H2O2, an enzymatic product of vascular adhesion protein‐1, as a new mechanism for the generation of an immunosuppressive tumor microenvironment in murine tumor models and some human cancers. Administration of a VAP‐1 inhibitor augmented tumor antigen‐specific CD8+ T cells by reversing this immunosuppressive condition, and showed synergistic anti‐tumor effects with ICIs including anti‐PD‐1 and CTLA‐4 Abs.
The STING and absent in melanoma 2 (AIM2) pathways are activated by the presence of cytosolic DNA, and STING agonists enhance immunotherapeutic responses. Here, we show that dendritic cell (DC) ...expression of AIM2 within human melanoma correlates with poor prognosis and, in contrast to STING, AIM2 exerts an immunosuppressive effect within the melanoma microenvironment. Vaccination with AIM2-deficient DCs improves the efficacy of both adoptive T cell therapy and anti-PD-1 immunotherapy for "cold tumors," which exhibit poor therapeutic responses. This effect did not depend on prolonged survival of vaccinated DCs, but on tumor-derived DNA that activates STING-dependent type I IFN secretion and subsequent production of CXCL10 to recruit CD8+ T cells. Additionally, loss of AIM2-dependent IL-1β and IL-18 processing enhanced the treatment response further by limiting the recruitment of regulatory T cells. Finally, AIM2 siRNA-treated mouse DCs in vivo and human DCs in vitro enhanced similar anti-tumor immune responses. Thus, targeting AIM2 in tumor-infiltrating DCs is a promising new treatment strategy for melanoma.
The three major conventional treatments: surgery, chemotherapy, and radiation therapy, have been commonly performed for lung cancer. However, lung cancer is still the leading cause of cancer-related ...mortality. Immunotherapy has recently emerged as a very effective new treatment modality, and there is now growing enthusiasm for cancer immunotherapy worldwide. However, the results of clinical studies using immunotherapy are not always favorable. Understanding the steps involved in the recognition and eradication of cancer cells by the immune system seems essential to understanding why past immunotherapies have failed and how current therapies can be optimally utilized. In addition, the combination of immunotherapies, such as cancer vaccines and immune checkpoint inhibitors, as well as the combination of these therapies with three conventional therapies, may pave the way for personalized immunotherapy. In this review, we summarize the results of immunotherapies used in phase III clinical trials, including immune checkpoint inhibitors, and discuss the future prospects of immunotherapies in lung cancer treatment.
To evaluate the feasibility of adoptive cell therapy (ACT) using ex vivo‐expanded tumor‐infiltrating lymphocytes (TILs) in Japanese patients with melanoma who failed immune‐checkpoint inhibitor ...therapy, an open‐label, single‐arm, pilot study was conducted. We investigated the immunological and genetic factors of the pretreatment tumor and expanded TILs that may be associated with the clinical response. The treatment protocol comprised preparation of TIL culture, lympho‐depleting non‐myeloablative preconditioning with cyclophosphamide and fludarabine, TIL infusion, and intravenous administration of low‐dose IL‐2. Three patients of clinical subtypes mucosal, superficial spreading, and acral melanoma underwent TIL‐ACT. Most severe adverse events, including fever and leukopenia, were manageable with the supportive regimen specified in the protocol, suggesting that the TIL‐ACT regimen is suitable for Japanese patients with melanoma. One patient showed a short‐term partial response, one relatively long‐stable disease, and one experienced disease progression. Whole‐exome and transcriptional sequencing of isolated tumor cells and immunohistochemical analyses before TIL‐ACT revealed various immunostimulatory factors, including a high tumor mutation burden and immune cell‐recruiting chemokines, as well as various immunosuppressive factors including TGF‐β, VEGF, Wnt/β‐catenin, and MAPK signaling and epithelial‐to‐mesenchymal transition, which might influence the efficacy of TIL‐ACT. Our results imply mechanisms for the antitumor effect of and resistance to TIL‐ACT. Further studies of immune‐resistant mechanisms of TIL‐ACT are warranted. This study is registered with the UMIN Clinical Trial Registry (UMIN 000011431).
Various factors involved in the balance of immunostimulation and immunosuppression are important in the TIL‐ACT response for melanoma patients.
Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy (GFAP-A) is an autoimmune inflammatory central nervous system disorder characterized by the detection of autoantibodies that recognize ...GFAP in CSF. The pathogenesis of GFAP-A is poorly understood. Some patients had a neoplasm detected and GFAP expressed by neoplasms is plausible as immunogen triggering paraneoplastic neurological autoimmunity.
We report a case of 76-year-old female patient with GFAP-A complicated with breast cancer. She presented with altered consciousness, nuchal rigidity, speech disturbances, and weakness. Her clinical symptoms were improved by immunotherapy and cancer treatments. Immunohistochemical analysis showed that the restricted tumor expressed GFAP. The infiltration of CD3 + T cells were observed in the peritumoral and intratumoral areas. The most common infiltrating lymphocytes were CD8 + T cells. CD4 + T cells and CD20 + B cells were also observed in the predominant peritumoral area.
These results suggest that GFAP-A may occur in a paraneoplastic neurological syndrome associated with breast cancer.
Chronic graft‐vs‐host disease (cGVHD) is a multifactorial inflammatory disease that affects patients undergoing hematopoietic stem cell transplantation. Multiple organs, including the lacrimal glands ...(LGs), are negatively affected by cGVHD and lose function due to the resultant fibrosis. An abnormal immune response is thought to be a major factor in the development of chronic ocular GVHD, which is currently treated primarily with immunosuppressive therapies. However, all the treatments yield unsatisfactory outcomes, and additional treatment strategies are needed. To meet this unmet medical need, we aimed to elucidate an additional pathway of chronic ocular GVHD. Our findings suggest a potential association between chronic ocular GVHD pathogenesis and stress‐induced cellular senescence through the senescence‐associated secretory phenotype (SASP). Senescent cells produce cytokines and chemokines, such as IL‐6 and CXCL9. Indeed, senescent cell accumulation was presumably associated with cGVHD development in LGs, as evidenced by the improvement in LGs after the selective elimination of senescent cells (senolysis) with ABT‐263. Results in the sclerodermatous cGVHD mouse model suggest that inhibiting the major components of the SASP, including IL‐6 and CXCL9, with senolytics is a potential novel strategy for treating cGVHD‐affected LGs. Taken together, our results indicate a potential association between the SASP and cGVHD development in LGs and suggest that targeted senolytic treatment may be a new therapeutic option for this disease.
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