Blockade of PD-L1 (B7-H1) augments human tumor-specific T cell responses in vitro

Companion diagnostics and predictive biomarkers for PD-1/PD-L1 immune checkpoint inhibitors therapy in malignant melanoma

Programmed cell death receptor 1 (PD-1), when bound to the ligand programmed death-ligand 1 (PD-L1), can suppress cellular immunity and play a critical role in the initiation and development of cancer. Immune drugs targeting these two sites have been developed for different cancers, including malignant melanoma. The accompanying diagnostic method has been approved by the FDA to guide patient medication. However, the method of immunohistochemical staining, which varies widely due to the antibody and staining cut-off values, has certain limitations in application and does not benefit all patients. Increasing researches begin to focus on new biomarkers to improve objective response rates and survival in cancer patients. In this article, we enumerated three major groups, including tumour microenvironment, peripheral circulation, and gene mutation, which covered the current main research directions. In the future, we hope those biomarkers may be used to guide the treatment of patients with malignant melanoma.

Synergistic Potential of Nanomedicine in Prostate Cancer Immunotherapy: Breakthroughs and Prospects

Given the global prevalence of prostate cancer in men, it is crucial to explore more effective treatment strategies. Recently, immunotherapy has emerged as a promising cancer treatment due to its unique mechanism of action and potential long-term effectiveness. However, its limited efficacy in prostate cancer has prompted renewed interest in developing strategies to improve immunotherapy outcomes. Nanomedicine offers a novel perspective on cancer treatment with its unique size effects and surface properties. By employing targeted delivery, controlled release, and enhanced immunogenicity, nanoparticles can be synergized with nanomedicine platforms to amplify the effectiveness of immunotherapy in treating prostate cancer. Simultaneously, nanotechnology can address the limitations of immunotherapy and the challenges of immune escape and tumor microenvironment regulation. Additionally, the synergistic effects of combining nanomedicine with other therapies offer promising clinical outcomes. Innovative applications of nanomedicine include smart nanocarriers, stimulus-responsive systems, and precision medicine approaches to overcome translational obstacles in prostate cancer immunotherapy. This review highlights the transformative potential of nanomedicine in enhancing prostate cancer immunotherapy and emphasizes the need for interdisciplinary collaboration to drive research and clinical applications forward.

Drug resistance and tumor immune microenvironment: An overview of current understandings (Review)

The use of antitumor drugs represents a reliable strategy for cancer therapy. Unfortunately, drug resistance has become increasingly common and contributes to tumor metastasis and local recurrence. The tumor immune microenvironment (TME) consists of immune cells, cytokines and immunomodulators, and collectively they influence the response to treatment. Epigenetic changes including DNA methylation and histone modification, as well as increased drug exportation have been reported to contribute to the development of drug resistance in cancers. In the past few years, the majority of studies on tumors have only focused on the development and progression of a tumor from a mechanistic standpoint; few studies have examined whether the changes in the TME can also affect tumor growth and drug resistance. Recently, emerging evidence have raised more concerns regarding the role of TME in the development of drug resistance. In the present review, it was discussed how the suppressive TME adapts to drug resistance characterized by the cooperation of immune cells, cytokines, immunomodulators, stromal cells and extracellular matrix. Furthermore, it was reviewed how these immunological or metabolic changes alter immuno‑surveillance and thus facilitate tumor drug resistance. In addition, potential targets present in the TME for developing novel therapeutic strategies to improve individualized therapy for cancer treatment were revealed.

Neoadjuvant toripalimab combined with axitinib in patients with locally advanced clear cell renal cell carcinoma: a single-arm, phase II trial

BACKGROUND

A combination of axitinib and immune checkpoint inhibitors (ICIs) demonstrated promising efficacy in the treatment of advanced renal cell carcinoma (RCC). This study aims to prospectively evaluate the safety, efficacy, and biomarkers of neoadjuvant toripalimab plus axitinib in non-metastatic clear cell RCC.

METHODS

This is a single-institution, single-arm phase II clinical trial. Patients with non-metastatic biopsy-proven clear cell RCC (T2-T3N0-1M0) are enrolled. Patients will receive axitinib 5 mg twice daily combined with toripalimab 240 mg every 3 weeks (three cycles) for up to 12 weeks. Patients then will receive partial (PN) or radical nephrectomy (RN) after neoadjuvant therapy. The primary endpoint is objective response rate (ORR). Secondary endpoints include disease-free survival, safety, and perioperative complication rate. Predictive biomarkers are involved in exploratory analysis.

RESULTS

A total of 20 patients were enrolled in the study, with 19 of them undergoing surgery. One patient declined surgery. The primary endpoint ORR was 45%. The posterior distribution of πORR had a mean of 0.44 (95% credible intervals: 0.24-0.64), meeting the predefined primary endpoint with an ORR of 32%. Tumor shrinkage was observed in 95% of patients prior to nephrectomy. Furthermore, four patients achieved a pathological complete response. Grade ≥3 adverse events occurred in 25% of patients, including hypertension, hyperglycemia, glutamic pyruvic transaminase/glutamic oxaloacetic transaminase (ALT/AST) increase, and proteinuria. Postoperatively, one grade 4a and eight grade 1-2 complications were noted. In comparison to patients with stable disease, responders exhibited significant differences in immune factors such as Arginase 1(ARG1), Melanoma antigen (MAGEs), Dendritic Cell (DC), TNF Superfamily Member 13 (TNFSF13), Apelin Receptor (APLNR), and C-C Motif Chemokine Ligand 3 Like 1 (CCL3-L1). The limitation of this trial was the small sample size.

CONCLUSION

Neoadjuvant toripalimab combined with axitinib shows encouraging activity and acceptable toxicity in locally advanced clear cell RCC and warrants further study.

TRIAL REGISTRATION NUMBER

clinicaltrials.gov, NCT04118855.

Several first-line anti-hypertensives act on fibrosarcoma progression and PD1ab blockade therapy

PURPOSE

Patients are typically diagnosed with both hypertension and fibrosarcoma. Medical oncologists must prescribe suitable anti-hypertensive medications while considering anti-tumor drugs. Recently, immunotherapy has become prominent in cancer treatment. Nonetheless, it is unknown what role anti-hypertensive medications will play in immunotherapy.

METHODS

We examined the effects of six first-line anti-hypertensive medications on programmed cell death protein 1 antibody (PD1ab) in tumor treatment using a mouse model of subcutaneous fibrosarcoma. The drugs examined were verapamil, losartan, furosemide, spironolactone, captopril, and hydrochlorothiazide (HCTZ). The infiltration of CD8+ T cells was examined by immunohistochemistry. Additionally, several in vitro and in vivo assays were used to study the effects of HCTZ on human fibrosarcoma cancer cells to explore its mechanism.

RESULTS

Verapamil suppressed tumor growth and showed an improved effect on the tumor inhibition of PD1ab. Captopril did not affect tumor growth but brought an unexpected benefit to PD1ab treatment. In contrast, spironolactone and furosemide showed no effect on tumor growth but had an offset effect on the PD1ab therapy. Consequently, the survival time of mice was also significantly reduced. Notably, losartan and HCTZ, especially HCTZ, promoted tumor growth and weakened the effect of PD1ab treatment. Consistent results were observed in vivo and in vitro using the human fibrosarcoma cell line HT1080. We determined that the Solute Carrier Family 12 Member 3 (SLC12A3), a known target of HCTZ, may be the principal factor underlying its effect-enhancing properties through mechanism studies employing The Cancer Genome Atlas (TCGA) data and in vivo and in vitro assays.

CONCLUSION

Verapamil and captopril potentiated the anti-tumor effect of PD1ab, whereas spironolactone and furosemide weakened the effect of PD1ab on tumor inhibition. Alarmingly, losartan and HCTZ promoted tumor growth and impaired the effect of PD1ab. Furthermore, we preliminarily found that HCTZ may promote tumor progression through SLC12A3. Based on this study, futher mechanism researches and clinical trials should be conducted in the future.

The role of dendritic cells in cancer immunity and therapeutic strategies

Dendritic cells (DCs) are asserted as the most potent antigen-presenting cells (APCs) that orchestrate both innate and adaptive immunity, being extremely effective in the induction of robust anti-cancer T cell responses. Hence, the modulation of DCs function represents an attractive target for improving cancer immunotherapy efficacy. A better understanding of the immunobiology of DCs, the interaction among DCs, immune effector cells and tumor cells in tumor microenvironment (TME) and the latest advances in biomedical engineering technology would be required for the design of optimal DC-based immunotherapy. In this review, we focus on elaborating the immunobiology of DCs in healthy and cancer environments, the recent advances in the development of enhancing endogenous DCs immunocompetence via immunomodulators as well as DC-based vaccines. The rapidly developing field of applying nanotechnology to improve DC-based immunotherapy is also highlighted.

Can neoadjuvant chemoradiotherapy combined with immunotherapy benefit patients with microsatellite stable locally advanced rectal cancer? a pooled and integration analysis

Objective

To assess the clinical efficacy of neoadjuvant chemoradiotherapy combined with immunotherapy for patients with microsatellite stable (MSS) locally advanced rectal cancer and provide evidence to support clinical decision-making.

Methods

A systematic search was conducted on the PubMed, Embase, Cochrane Collaboration databases, conference summaries, and Chinese databases for clinical studies that investigated neoadjuvant chemoradiotherapy combined with immunotherapy for the treatment of locally advanced rectal cancer with MSS status. The search spanned from the inception of each database through July 2023. Data from the identified studies were extracted using a pre-designed table, and efficacy outcomes were analyzed. An integrated analysis was conducted using Stata 12.0 software.

Results

Eight studies were included, comprising 204 patients with locally advanced MSS rectal cancer who received chemoradiotherapy combined with immunotherapy. The integrated analysis revealed a pathologic complete remission rate of 0.33, a sphincter preservation rate of 0.86, an R0 resection rate of 0.83, a major pathologic remission rate of 0.33, and a clinical complete remission rate of 0.30.

Conclusion

Neoadjuvant chemoradiotherapy combined with immunotherapy demonstrates significant short-term efficacy in MSS-type locally advanced rectal cancer, notably enhancing the pathologic complete remission and sphincter preservation rates. This combination is a recommended treatment for patients with MSS-type rectal cancer.

Verapamil modulates NFAT2 to inhibit tumor growth and potentiates PD1ab immune checkpoint inhibitor therapy in cervical cancer treatment

PURPOSE

Current evidence suggests a high co-prevalence of hypertension and cervical cancer. Accordingly, blood pressure control is indicated during anti-tumor drug therapy in this patient population. Over the past few years, immunotherapy has made great strides in treating different cancers. However, the role and clinical significance of verapamil as a first-line anti-hypertensive drug during immunotherapy remain poorly understood, emphasizing the need for further studies.

METHODS

Murine cervical cancer models were employed to assess the effect of verapamil monotherapy and combination with PD1ab. Immunohistochemistry was conducted to quantify the abundance of CD8+ T cell and Ki67+ cells. Several in-vitro and in-vivo assays were used to study the effects of verapamil and explore the preliminary mechanism.

RESULTS

Monotherapy with verapamil or PD1ab immune checkpoint inhibitor significantly suppressed the growth of subcutaneously grafted U14 cells in WT BABL/c mice, respectively, with increased survival time of mice. Consistent results were observed in the melanoma model. Furthermore, we substantiated that verapamil significantly impaired tumor proliferation and migration of SiHa human cervical cancer cells in vitro and in vivo. In silico analysis using TCGA data revealed that NFAT2 expression negatively correlated with patient survival. The CCK8 assay revealed that verapamil abrogated the stimulatory effect of NFAT2 after knockdown of NFAT2.

CONCLUSIONS

Our results suggest that verapamil inhibits tumor growth by modulating NFAT2 expression and enhancing tumor immune responses to PD1ab, which can be harnessed for cervical cancer therapy, especially for patients with comorbid hypertension. Indeed, further clinical trials are warranted to increase the robustness of our findings.

Propranolol-Loaded Trehalosome as Antiproliferative Agent for Treating Skin Cancer: Optimization, Cytotoxicity, and In Silico Studies

This study aims at preparing propranolol-loaded trehalosomes (a trehalose-coated liposome) to be used as an antiproliferative agent for treating skin cancer. A factorial design was used to select the optimum formula, where trehalose, lecithin, and Tween 80 levels were studied. A total of 24 runs were prepared and characterized according to size, charge, entrapment efficiency, and release after 3 h to select the optimum formula. The optimized formula was investigated using TEM, DSC, and FTIR. Cell studies were carried out against the human melanoma cell line to measure cytotoxicity, apoptosis/necrosis, and cell cycle arrest. In silico studies were conducted to understand the interaction between propranolol and the influential receptors in melanoma. The results showed the selected formula consisted of trehalose (175 mg), lecithin (164 mg), and Tween 80 (200 mg) with a size of 245 nm, a charge of -9 mV, an EE% of 68%, and a Q3 of 62%. Moreover, the selected formula has good cytotoxicity compared to the free drug due to the synergistic effect of the drug and the designed carrier. IC50 of free propranolol and the encapsulation of propranolol were 17.48 μg/mL and 7.26 μg/mL, respectively. Also, propranolol and the encapsulation of propranolol were found to significantly increase early and late apoptosis, in addition to inducing G1 phase cell cycle arrest. An in silico virtual study demonstrated that the highest influential receptors in melanoma were the vitamin D receptor, CRH-R1, VEGFR 1, and c-Kit, which matches the results of experimental apoptotic and cell cycle analysis. In conclusion, the selected formula has good cytotoxicity compared to the free drug due to the synergistic effect of the drug and the designed carrier, which make it a good candidate as an antiproliferative agent for treating skin cancer.

TOPK mediates immune evasion of renal cell carcinoma via upregulating the expression of PD-L1

Although anti-PD-L1 therapy has been used in the clinical treatment of renal cell carcinoma (RCC), a proportion of patients are not sensitive to it, which may be attributed to the heterogeneity of PD-L1 expression. Here, we demonstrated that high TOPK (T-LAK cell-originated Protein Kinase) expression in RCC promoted PD-L1 expression by activating ERK2 and TGF-β/Smad pathways. TOPK was positively correlated with PD-L1 expression levels in RCC. Meanwhile, TOPK significantly inhibited the infiltration and function of CD8⁺ T cells and promoted the immune escape of RCC. Moreover, inhibition of TOPK significantly enhanced CD8⁺ T cell infiltration, promoted CD8⁺ T cell activation, enhanced anti-PD-L1 therapeutic efficacy, and synergistically enhanced anti-RCC immune response. In conclusion, this study proposes a new PD-L1 regulatory mechanism that is expected to improve the effectiveness of immunotherapy for RCC.

Treatment patterns and outcomes of patients with metastatic non-small cell lung cancer in five European countries: a real-world evidence survey

BACKGROUND

The landscape of non-small cell lung cancer (NSCLC) therapy is rapidly changing. This analysis aimed to understand patient characteristics, diagnosis and treatment patterns in patients with metastatic NSCLC (mNSCLC) without EGFR and ALK mutations across five European countries.

METHODS

Data were drawn from the Adelphi NSCLC Disease Specific Programme™, a point-in-time survey of oncologists/pulmonologists and their consulting patients in France, Germany, Italy, Spain and UK. Physicians completed record forms (RFs) for the next six consecutive consulting patients with advanced NSCLC, who then voluntarily completed questionnaires. As an oversample, physicians provided a further ten RFs specifically for patients with EGFR-wild-type mNSCLC: five patients diagnosed before March 2020 (pre-SARS-CoV-2 [COVID-19]) and five patients diagnosed from March 2020 (during COVID-19). Only EGFR-wild-type/ALK-wild-type patients were included for analysis.

RESULTS

Mean (standard deviation [SD]) age for 1073 patients with EGFR-wild-type/ALK-wild-type mNSCLC was 66.2 (8.9) years, 65.2% were male and 63.7% had adenocarcinoma. Level of PD-L1 expression at advanced diagnosis was < 1% for 23.1% of patients, 1-49% for 40.9% and ≥ 50% for 36.0%. Most common first-line (1L) advanced treatment was chemotherapy only (36.9%), immunotherapy monotherapy (30.5%) or immunotherapy + chemotherapy (27.6%). Of 158 patients who had progressed beyond 1L therapy, the mean (SD) time-to-treatment discontinuation was 5.1 (4.3) months; 75.9% of whom completed their 1L treatment as intended. A complete response was achieved by 6.7% and a partial response by 69.2% of patients. Of 38 patients who discontinued 1L treatment early, disease progression was reported for 73.7%. Quality of life (QoL) reported by patients was generally lower than normative reference values. Of 2373 oversample patients, physicians reported management changes for 34.7% due to COVID-19, ranging from 19.6% in Germany to 79.7% in the UK. Immunotherapy was prescribed as 1L NSCLC treatment during COVID-19 for 64.2% (n = 786) of patients and pre-COVID-19, for 47.8% (n = 549).

CONCLUSIONS

Real-world treatment patterns suggest that chemotherapy use remains high despite guidelines recommending immunotherapy-based 1L treatment for mNSCLC. QoL reported by patients was generally lower than population reference values. Not implying causality, 1L immunotherapy use was higher during COVID-19 than pre-COVID-19, and the UK saw the biggest impact to patient management due to COVID-19.

IFN-γ signature enables selection of neoadjuvant treatment in patients with stage III melanoma

Neoadjuvant ipilimumab + nivolumab has demonstrated high pathologic response rates in stage III melanoma. Patients with low intra-tumoral interferon-γ (IFN-γ) signatures are less likely to benefit. We show that domatinostat (a class I histone deacetylase inhibitor) addition to anti-PD-1 + anti-CTLA-4 increased the IFN-γ response and reduced tumor growth in our murine melanoma model, rationalizing evaluation in patients. To stratify patients into IFN-γ high and low cohorts, we developed a baseline IFN-γ signature expression algorithm, which was prospectively tested in the DONIMI trial. Patients with stage III melanoma and high intra-tumoral IFN-γ scores were randomized to neoadjuvant nivolumab or nivolumab + domatinostat, while patients with low IFN-γ scores received nivolumab + domatinostat or ipilimumab + nivolumab + domatinostat. Domatinostat addition to neoadjuvant nivolumab ± ipilimumab did not delay surgery but induced unexpected severe skin toxicity, hampering domatinostat dose escalation. At studied dose levels, domatinostat addition did not increase treatment efficacy. The baseline IFN-γ score adequately differentiated patients who were likely to benefit from nivolumab alone versus patients who require other therapies.

Establishment of Cell-Based Assay System for Evaluating Cytotoxic Activity Modulated by the Blockade of PD-1 and PD-L1 Interactions with a Therapeutic Antibody

BACKGROUND

Therapeutic antibodies targeting the PD-1/PD-L1 immune checkpoint are widely used in cancer therapy and are under active further development. Historically, the antitumor activity of PD-1/PD-L1 immune checkpoint inhibitors has been evaluated using in vivo and ex vivo test methods; however, a simple in vitro assay method to evaluate antitumor activity accurately is needed for the efficient development of new therapeutic agents. In the present study, we attempted to establish a simple cell-based assay system to evaluate the modulating effect of PD-1/PD-L1 immune checkpoint inhibitors on cytotoxic activity.

METHODS

We established a new natural killer (NK) cell line stably transfected with the PD-1 and IL-2 genes and a new NK-sensitive target cell line stably transfected with the PD-L1 gene. Then, the assay system was established by co-cultivation of the established cell lines and measurement of the cytotoxic activities using the europium release assay. To confirm the performance of the established assay system, model therapeutic antibodies to block the PD-1/PD-L1 signal, nivolumab and atezolizumab were added to the co-culture system and the modulating effect on the cytotoxic activities were evaluated.

RESULTS

Nivolumab and atezolizumab clearly showed a modulating effect on cytotoxic activity in a dose-dependent manner in our assay system, whereas a human IgG isotype control antibody did not show any modulating effect on the assay system.

CONCLUSION

The newly established cell-based assay system can quantitatively evaluate the modulating effect of PD-1/PD-L1 immune checkpoint inhibitors by measuring cytotoxic activity, playing an important role in antitumor effects as innate immunity.

The stromal tumor-infiltrating lymphocytes, cancer stemness, epithelial-mesenchymal transition, and B7-H4 expression in ovarian serous carcinoma

BACKGROUND

B7-H4 is expressed in various types of cancers and its expression inversely correlates with the degree of tumor-infiltrating lymphocytes (TILs). Studies have shown the relationship between B7-H4, cancer stem cell (CSC) properties, and epithelial-mesenchymal transition (EMT) in various cancers. However, very few studies have investigated the relationship between B7-H4, TILs, cancer stemness, and EMT in epithelial ovarian cancer (EOC). The present study aimed to elucidate whether B7-H4 is involved in immune evasion and examine whether B7-H4 is associated with cancer stemness or EMT in ovarian serous carcinoma, the most common type of EOC. The clinical significance of B7-H4 was also investigated to evaluate its potential as a therapeutic target.

METHODS

A total of 145 patients included in this study. The degree of stromal TILs was evaluated using hematoxylin and eosin (H&E)-stained slides. Immunohistochemical analysis of B7-H4, CSC-related biomarkers (CD24, CD44s, CD133, and ALDH1), and EMT-related biomarkers (E-cadherin, N-cadherin, and vimentin) was performed using tissue microarray. qRT-PCR for VTCN1, CD24, CD44, PROM1, ALDH1, CDH1, CDH2, and VIM genes was performed on 38 frozen tissue samples. The mRNA expression levels were analyzed using Gene Expression Profiling Interactive Analysis (GEPIA) online analysis tool.

RESULTS

B7-H4 protein expression positively correlated with the degree of stromal TILs. CD24, CD44s, and CD133 expression showed a positive correlation with B7-H4 expression at both the protein and mRNA levels, but ALDH1 correlated only at the protein level. E-cadherin expression was positively correlated with B7-H4 expression at both the protein and mRNA levels. N-cadherin and vimentin expression was inversely related to B7-H4 expression only at the mRNA level. B7-H4 positive patients were associated with higher tumor grade and lower overall survival rate than B7-H4 negative patients, especially in ovarian serous carcinoma with low stromal TILs.

CONCLUSIONS

The present study demonstrates that B7-H4 may not be involved in the immune evasion mechanism, but is involved in cancer stemness and mesenchymal-epithelial transition. In addition, B7-H4 may be a therapeutic target for the treatment of ovarian serous carcinoma, especially with low stromal TILs.

Advances in Nanotechnology for Cancer Immunoprevention and Immunotherapy: A Review

One of the most effective cancer therapies, cancer immunotherapy has produced outstanding outcomes in the field of cancer treatment. However, the cost is excessive, which limits its applicability. A smart way to address this issue would be to apply the knowledge gained through immunotherapy to develop strategies for the immunoprevention of cancer. The use of cancer vaccines is one of the most popular methods of immunoprevention. This paper reviews the technologies and processes that support the advantages of cancer immunoprevention over traditional cancer immunotherapies. Nanoparticle drug delivery systems and nanoparticle-based nano-vaccines have been employed in the past for cancer immunotherapy. This paper outlines numerous immunoprevention strategies and how nanotechnology can be applied in immunoprevention. To comprehend the non-clinical and clinical evaluation of these cancer vaccines through clinical studies is essential for acceptance of the vaccines.

Development of a human phage display-derived anti-PD-1 scFv antibody: an attractive tool for immune checkpoint therapy

Background

The PD-1 checkpoint pathway plays a major role in tumor immune evasion and the development of the tumor microenvironment. Clinical studies show that therapeutic antibodies blocking the PD-1 pathway can restore anti-tumor or anti-virus immune responses by the reinvigoration of exhausted T cells. Because of the promising results of anti-PD-1 monoclonal antibodies in cancer treatment, autoimmune disorders, and infectious diseases, the PD-1 has emerged as an encouraging target for different diseases.

Results

In the present study, we employed a human semi-synthetic phage library for isolation of some scFvs against the extracellular domain of PD-1 protein by panning process. After the panning, a novel anti-PD-1 scFv (SS107) was found that exhibited specific binding to PD-1 antigen and stimulated Jurkat T cells. The selected anti-PD-1 scFv could restore the production of IL-2 and IFN-γ by Jurkat T cells that were co-cultured with PD-L1 positive tumor cells.

Conclusion

This anti-PD-1 scFv with high specificity and the ability to reactivate exhausted T cells has the potential to be developed as an anti-cancer agent or to be used in combination with other therapeutic approaches.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12896-022-00752-8.

The Effects of 6 Common Antidiabetic Drugs on Anti-PD1 Immune Checkpoint Inhibitor in Tumor Treatment

Diabetes and cancer are common diseases and are frequently diagnosed in the same individual. These patients need to take antidiabetic drugs while receiving antitumor drugs therapy. Recently, immunotherapy offers significant advances for cancer treatment. However, it is unclear whether antidiabetic drugs affect immunotherapy. Here, by employing syngeneic mouse colon cancer model and melanoma model, we studied the effects of 6 common antidiabetic drugs on anti-PD1 immune checkpoint inhibitor in tumor treatment, including acarbose, sitagliptin, metformin, glimepiride, pioglitazone, and insulin. We found that acarbose and sitagliptin enhanced the tumor inhibition of anti-PD1, and metformin had no effect on the tumor inhibition of anti-PD1, whereas glimepiride, pioglitazone, and insulin weakened the tumor inhibition of anti-PD1. Our study suggests that cancer patients receiving anti-PD1 antibody therapy need serious consideration when choosing antidiabetic drugs. In particular, acarbose significantly inhibited tumor growth and further enhanced the therapeutic effect of anti-PD1, which can be widely used in tumor therapy. Based on this study, further clinical trials are expected.

A review of PD-1/PD-L1 siRNA delivery systems in immune T cells and cancer cells

OBJECTIVES

Programmed cell death 1 (PD-1) is a member of the CD28/CTLA-4 family of inhibitory immunological checkpoint receptors that's also widely produced by exhausted T lymphocytes in an immunosuppressive tumor microenvironment. PD-1 binds to programmed death ligand (PD-L1) and suppresses anti-cancer activity of T lymphocytes. We examined the current literature on how siRNA delivery systems can be used to target PD-1 and PD-L1, as well as the anti-cancer mechanisms and challenges associated with siRNA molecules. We look at studies that use program death 1 siRNA or program death 1 ligand siRNA to treat cancer. Several databases have been used for this purpose, including NCBI, Scopus, and Google Scholar.

KEY FINDINGS

This study looked at several methods for delivering siRNA to immune cells and cancer cells. According to these findings, suppressing PD-1 in T cells increases T lymphocyte activity. PD-L1 suppression in DCs improves antigen presentation and co-stimulatory signals on their surface, resulting in T cell activation. Chemotherapy resistance and cancer cell suppression of T cells are reduced when PD-L1/2 is suppressed in cancer cells.

CONCLUSION

The findings of this study indicated that several strategies for siRNA transfection to immune and cancer cells have been evaluated in recent decades, some of which effectively transfect siRNA to target cells, and defined PD-1 siRNA as a promising strategy for cancer treatment.

Generation, secretion and degradation of cancer immunotherapy target PD-L1

Cancer immunotherapy is a rapidly developing and effective method for the treatment of a variety of malignancies in recent years. As a significant immune checkpoint, programmed cell death 1 ligand 1 (PD-L1) and its receptor programmed cell death protein 1 (PD-1) play the most significant role in cancer immune escape and cancer immunotherapy. Though PD-L1 have become an important target for drug development and there have been various approved drugs and clinic trials targeting it, and various clinical response rate and adverse reactions prevent many patients from benefiting from it. In recent years, combination trials have become the main direction of PD-1/PD-L1 antibodies development. Here, we summarized PD-L1 biofunctions and key roles in various cancers along with the development of PD-L1 inhibitors. The regulators that are involved in controlling PD-L1 expression including post-translational modification, mRNA level regulation as well as degradation and exosome secretory pathway of PD-L1 were focused. This systematic summary may provide comprehensive understanding of different regulations on PD-L1 as well as a broad prospect for the search of the important regulator of PD-L1. The regulatory factors of PD-L1 can be potential targets for immunotherapy and increase strategies of immunotherapy in combination.

Characterization of INCB086550: A Potent and Novel Small-Molecule PD-L1 Inhibitor

Blocking the activity of the programmed cell death protein 1 (PD-1) inhibitory receptor with therapeutic antibodies against either the ligand (PD-L1) or PD-1 itself has proven to be an effective treatment modality for multiple cancers. Contrasting with antibodies, small molecules could demonstrate increased tissue penetration, distinct pharmacology, and potentially enhanced antitumor activity. Here, we describe the identification and characterization of INCB086550, a novel, oral, small-molecule PD-L1 inhibitor. In vitro, INCB086550 selectively and potently blocked the PD-L1/PD-1 interaction, induced PD-L1 dimerization and internalization, and induced stimulation-dependent cytokine production in primary human immune cells. In vivo, INCB086550 reduced tumor growth in CD34+ humanized mice and induced T-cell activation gene signatures, consistent with PD-L1/PD-1 pathway blockade. Preliminary data from an ongoing phase I study confirmed PD-L1/PD-1 blockade in peripheral blood cells, with increased immune activation and tumor growth control. These data support continued clinical evaluation of INCB086550 as an alternative to antibody-based therapies.

SIGNIFICANCE

We have identified a potent small-molecule inhibitor of PD-L1, INCB086550, which has biological properties similar to PD-L1/PD-1 monoclonal antibodies and may represent an alternative to antibody therapy. Preliminary clinical data in patients demonstrated increased immune activation and tumor growth control, which support continued clinical evaluation of this approach. See related commentary by Capparelli and Aplin, p. 1413. This article is highlighted in the In This Issue feature, p. 1397.

Anti-PD-L1 Antibody Enhances T Cell Immune Responses and Reduces Resistance of Breast Cancer Cells to Radiotherapy

Immune escape is a frequent occurrence, which limits the duration of antitumor immune responses to radiotherapy. Here, we aimed to ascertain the roles and underlying mechanisms of programmed death ligand 1 (PD-L1) in tolerance of breast cancer (BC) to radiotherapy. We first quantified microRNA-21 (miR-21) and PD-L1 expression in BC tissues and cells, followed by identification of the interactions between miR-21, PD-L1, and programmed cell death protein 4 (PDCD4). miR-21 knock-in mice were used to construct tumor-bearing models, which were then treated with anti-PD-L1 antibody and irradiation, followed by measurement of tumor growth and tumor immune escape. Finally, we evaluated the synergistic effects of radiotherapy and anti-PD-L1 antibody in vivo. The results showed increased miR-21 expression in BC tissues and cells, which was positively correlated with PD-L1 expression. The treatment with radiotherapy or anti-PD-L1 antibody in the miR-21 knock-in mice diminished tumor weight and volume, along with decreased CD3⁺CD8⁺ positive cells, serum IL-2 and IFN-γ levels, and lower PD-L1 expression, but augmented apoptosis of T and BC cells. Moreover, miR-21 significantly augmented PD-L1 expression via PI3K/Akt pathway activation by targeting PDCD4 in BC cells. Thus, radiotherapy and anti-PD-L1 antibody synergistically accelerated the therapeutic effect against BC in mice, thereby implicating a close interplay between radiotherapy, T cells, and the miR-21/PDCD4/PI3K/Akt/PD-L1 axis.

The Impact of the Microbiome on Resistance to Cancer Treatment with Chemotherapeutic Agents and Immunotherapy

Understanding the mechanisms of resistance to therapy in human cancer cells has become a multifaceted limiting factor to achieving optimal cures in cancer patients. Besides genetic and epigenetic alterations, enhanced DNA damage repair activity, deregulation of cell death, overexpression of transmembrane transporters, and complex interactions within the tumor microenvironment, other mechanisms of cancer treatment resistance have been recently proposed. In this review, we will summarize the preclinical and clinical studies highlighting the critical role of the microbiome in the efficacy of cancer treatment, concerning mainly chemotherapy and immunotherapy with immune checkpoint inhibitors. In addition to involvement in drug metabolism and immune surveillance, the production of microbiota-derived metabolites might represent the link between gut/intratumoral bacteria and response to anticancer therapies. Importantly, an emerging trend of using microbiota modulation by probiotics and fecal microbiota transplantation (FMT) to overcome cancer treatment resistance will be also discussed.

A Novel Type of PD-L1 Inhibitor rU1 snRNPA From Human-Derived Protein Scaffolds Library

Three marketed anti-PD-L1 antibodies almost have severe immune-mediated side effects. The therapeutic effects of anti-PD-L1 chemical inhibitors are not satisfied in the clinical trials. Here we constructed human-derived protein scaffolds library and screened scaffolds with a shape complementary to the PD-1 binding domain of PD-L1. The RNA binding domain of U1 snRNPA was selected as one of potential binders because it had the most favorable binding energies with PD-L1 and conformed to pre-established biological criteria for the screening of candidates. The recombinant U1 snRNPA (rU1 snRNPA) in Escherichia coli exhibits anti-cancer activity in melanoma and breast cancer by reactivating tumor-suppressed T cells in vitro and anti-melanoma activity in vivo. Considering hydrophobic and electrostatic interactions, three residues were mutated on the interface of U1 snRNPA and PD-L1 complex, and the ranked variants by PatchDock and A32D showed an increased active phenotype. The screening of human-derived protein scaffolds may become the potential development of therapeutic agents.

IFN-γ-induced PD-L1 expression on human melanocytes is impaired in vitiligo

Mounting evidence shows that the PD-1/PD-L1 axis is involved in tumor immune evasion. This is demonstrated by anti-PD-1 antibodies that can reverse tumor-associated PD-L1 to functionally suppress anti-tumor T-cell responses. Since type I and II interferons are key regulators of PD-L1 expression in melanoma cells and IFN-γ-producing CD8⁺ T cells and IFN-α-producing dendritic cells are abundant in vitiligo skin, we aimed to study the role of PD-1/PD-L1 signalling in melanocyte destruction in vitiligo. Moreover, impaired PD-1/PD-L1 function is observed in a variety of autoimmune diseases. It is, therefore, hypothesized that manipulating PD-1/PD-L1 signalling might have therapeutic potential in vitiligo. The PD-1⁺ T cells were abundantly present in situ in perilesional vitiligo skin, but expression of PD-L1 was limited and confined exclusively to dermal T cells. More specifically, neither melanocytes nor other epidermal skin cells expressed PD-L1. Exposure to IFN-γ, but also type I interferons, increased PD-L1 expression in primary melanocytes and fibroblasts, derived from healthy donors. Primary human keratinocytes only showed increased PD-L1 expression upon stimulation with IFN-γ. More interestingly, melanocytes derived from non-lesional vitiligo skin showed no PD-L1 upregulation upon IFN-γ exposure, while other skin cells displayed significant PD-L1 expression after exposure. In a vitiligo skin explant model, incubation of non-lesional vitiligo skin with activated (IFN-γ-producing) T cells from vitiligo lesions was previously described to induce melanocyte apoptosis. Although PD-L1 expression was induced in epidermal cells in these explants, this induction was completely absent in melanocytes. The lack of PD-L1 upregulation by melanocytes in the presence of IFN-γ-producing T cells shows that melanocytes lack protection against T-cell attack during vitiligo pathogenesis. Manipulating PD-1/PD-L1 signalling may, therefore, be a therapeutic option for vitiligo patients.

The double-edged sword: Harnessing PD-1 blockade in tumor and autoimmunity

Immune checkpoint blockade has demonstrated success in treating cancer but can lead to immune-related adverse events (irAEs), illustrating the centrality of these pathways in tolerance. Here, we describe programmed cell death protein 1 (PD-1) control of T cell responses, focusing on its unique restraint of regulatory T cell function. We examine successes and limitations of checkpoint blockade immunotherapy and review clinical and mechanistic features of irAEs. Last, we discuss strategies to modulate PD-1 blockade to enhance antitumor immunity while limiting autoimmunity.

Reinforcing the Combinational Immuno-Oncotherapy of Switching "Cold" Tumor to "Hot" by Responsive Penetrating Nanogels

Although immuno-oncotherapy in clinic has gained great success, the immunosuppressive tumor microenvironment (TME) existing in the "cold" tumor with insufficient and exhausted lymphocytes may result in a lower-than-expected therapeutic efficiency. Therefore, a properly designed synergistic strategy that can effectively turn the "cold" tumor to "hot" should be considered to improve the therapeutic effects of immuno-oncotherapy. Herein, TME-responsive penetrating nanogels (NGs) were developed, which can improve the delivery and penetration of the co-loaded resiquimod (R848) and green tea catechin (EGCG) in tumors by a nano-sized controlled releasing system of the soluble cyclodextrin-drug inclusion complex. Consequently, the NGs effectively promoted the maturation of dendritic cells, stimulated the cytotoxic T lymphocytes (CTLs), and decreased the PD-L1 expression in tumors. The combination of NGs with the OX40 agonist (αOX40) further synergistically enhanced the activation and infiltration of CTLs into the deep tumor and inhibited the suppression effects from the regulatory T cells (Tregs). As a result, an increased ratio of active CTLs to Tregs in tumors (20.66-fold) was achieved with a 91.56% tumor suppression effect, indicating a successful switch of "cold" tumors to "hot" for an immunologically beneficial TME with significantly improved anti-tumor immune therapeutics. This strategy could be tailored to other immuno-oncotherapeutic approaches to solve the urgent efficiency concerns of the checkpoint-based treatment in clinic.

Recent Advances in Engineered Materials for Immunotherapy-Involved Combination Cancer Therapy

Immunotherapy that can activate immunity or enhance the immunogenicity of tumors has emerged as one of the most effective methods for cancer therapy. Nevertheless, single-mode immunotherapy is still confronted with several critical challenges, such as the low immune response, the low tumor infiltration, and the complex immunosuppression tumor microenvironment. Recently, the combination of immunotherapy with other therapeutic modalities has emerged as a powerful strategy to augment the therapeutic outcome in fighting against cancer. In this review, recent research advances of the combination of immunotherapy with chemotherapy, phototherapy, radiotherapy, sonodynamic therapy, metabolic therapy, and microwave thermotherapy are summarized. Critical challenges and future research direction of immunotherapy-based cancer therapeutic strategy are also discussed.

The Next-Generation of Combination Cancer Immunotherapy: Epigenetic Immunomodulators Transmogrify Immune Training to Enhance Immunotherapy

Cancer immunotherapy harnesses the immune system by targeting tumor cells that express antigens recognized by immune system cells, thus leading to tumor rejection. These tumor-associated antigens include tumor-specific shared antigens, differentiation antigens, protein products of mutated genes and rearrangements unique to tumor cells, overexpressed tissue-specific antigens, and exogenous viral proteins. However, the development of effective therapeutic approaches has proven difficult, mainly because these tumor antigens are shielded, and cells primarily express self-derived antigens. Despite innovative and notable advances in immunotherapy, challenges associated with variable patient response rates and efficacy on select tumors minimize the overall effectiveness of immunotherapy. Variations observed in response rates to immunotherapy are due to multiple factors, including adaptative resistance, competency, and a diversity of individual immune systems, including cancer stem cells in the tumor microenvironment, composition of the gut microbiota, and broad limitations of current immunotherapeutic approaches. New approaches are positioned to improve the immune response and increase the efficacy of immunotherapies, highlighting the challenges that the current global COVID-19 pandemic places on the present state of immunotherapy.

Immune checkpoint inhibition in classical hodgkin lymphoma

Introduction: Hodgkin lymphoma (HL) accounts for 10% of lymphoma cases every year. HL is often curable by conventional chemotherapy and radiotherapy. However, in case of relapsed or refractory HL (r/r HL) after autologous hematopoietic stem cell transplantation (ASCT), few treatment options are currently available. Blockade of the immune checkpoint receptors, programmed death receptor-1 (PD-1), or cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) expressed on T-cells, and their ligands expressed on tumor-associated antigen-presenting cells (APCs), and Hodgkin and Reed/Sternberg (HRS) cells can remove inhibitory signals from anti-tumor T cells. Checkpoint blockade using monoclonal antibodies could be a potential treatment. Nivolumab and pembrolizumab are approved antibodies for the treatment of r/r HL.Areas covered: This paper provides a comprehensive discussion of checkpoint inhibitors in HL treatment, including the most important clinical trials with mono- or combination therapies as a first or second-line treatment of HL.Expert opinion: Relatively high response rates and an acceptable safety profile of checkpoint inhibitors make them an effective therapy for HL. The combination of checkpoint inhibition with other conventional cancer treatments and identifying the mechanisms responsible for resistance to checkpoint inhibition may improve the efficacy and safety of this immunotherapy, and enhance patient quality of life.

Cancer Immunoprevention: Current Status and Future Directions

Cancer is one of the most serious diseases affecting health and the second leading cause of death worldwide. Despite the development of various therapeutic modalities to deal with cancer, limited improvement in overall survival of patients has been yielded. Since there is no certain cure for cancer, detection of premalignant lesions, and prevention of their progression are vital to the decline of high morbidity and mortality of cancer. Among approaches to cancer prevention, immunoprevention has gained further attention in recent years. Deep understanding of the tumor/immune system interplay and successful prevention of virally-induced malignancies by vaccines have paved the way toward broadening cancer immunoprevention application. The identification of tumor antigens in premalignant lesions was the turning point in cancer immunoprevention that led to designing preventive vaccines for various malignancies including multiple myeloma, colorectal, and breast cancer. In addition to vaccines, immune checkpoint inhibitors are also being tested for the prevention of oral squamous cell carcinoma (SCC), and imiquimod which is an established drug for the prevention of skin SCC, is a non-specific immunomodulator. Herein, to provide a bench-to-bedside understanding of cancer immunoprevention, we will review the role of the immune system in suppression and promotion of tumors, immunoprevention of virally-induced cancers, identification of tumor antigens in premalignant lesions, and clinical advances of cancer immunoprevention.

PD-L1 immunohistochemistry for canine cancers and clinical benefit of anti-PD-L1 antibody in dogs with pulmonary metastatic oral malignant melanoma

Immunotherapy targeting programmed cell death 1 (PD-1) and PD-ligand 1 (PD-L1) represents promising treatments for human cancers. Our previous studies demonstrated PD-L1 overexpression in some canine cancers, and suggested the therapeutic potential of a canine chimeric anti-PD-L1 monoclonal antibody (c4G12). However, such evidence is scarce, limiting the clinical application in dogs. In the present report, canine PD-L1 expression was assessed in various cancer types, using a new anti-PD-L1 mAb, 6C11-3A11, and the safety and efficacy of c4G12 were explored in 29 dogs with pulmonary metastatic oral malignant melanoma (OMM). PD-L1 expression was detected in most canine malignant cancers including OMM, and survival was significantly longer in the c4G12 treatment group (median 143 days) when compared to a historical control group (n = 15, median 54 days). In dogs with measurable disease (n = 13), one dog (7.7%) experienced a complete response. Treatment-related adverse events of any grade were observed in 15 dogs (51.7%). Here we show that PD-L1 is a promising target for cancer immunotherapy in dogs, and dogs could be a useful large animal model for human cancer research.

Expression of Human Epidermal Growth Factor Receptor-2 Status and Programmed Cell Death Protein-1 Ligand Is Associated With Prognosis in Gastric Cancer

Background

PD-L1 and HER-2 are routine biomarkers for gastric cancer (GC). However, little research has been done to investigate the correlation among PD-L1, HER-2, immune microenvironment, and clinical features in GC.

Methods

Between January 2013 and May 2020, a total of 120 GC patients treated with chemotherapy were admitted to Henan Tumor Hospital. We retrospectively identified PD-L1, HER-2 level before chemotherapy and abstracted clinicopathologic features and treatment outcomes. Univariate and multivariate survival analyses were performed to assess the relationship between PD-L1/HER-2 levels and progression-free survival (PFS). The mRNA and tumor microenvironment of 343 patients with GC from The Cancer Genome Atlas (TCGA) were used to explore the underlying mechanism.

Results

We retrospectively analyzed 120 patients with gastric cancer, including 17 patients with HER-2 positive and 103 patients with HER-2 negative GC. The results showed that the expression of PD-L1 was closely correlated with HER-2 (P = 0.015). Patients with PD-L1/HER-2 positive obtained lower PFS compared to PD-L1/HER-2 negative (mPFS: 6.4 vs. 11.1 months, P = 0.014, mPFS: 5.3 vs. 11.1 months, P = 0.002, respectively), and the PD-L1 negative and HER-2 negative had the best PFS than other groups (P = 0.0008). In a multivariate model, PD-L1 status, HER-2 status, tumor location, and tumor differentiation remained independent prognostic indicators for PFS (P < 0.05). The results of database further analysis showed that the proportion of PD-L1+/CD8A+ in HER-2 negative patients was higher than that in HER-2 positive patients (37.6 vs 20.3%), while PD-L1−/CD8A− was significantly higher in HER-2 positive patients than HER-2 negative patients (57.8 vs. 28.8%). In addition, it showed that not only CD4+T cells, macrophages, and CD8+T cells, but also the associated inflammatory pathways such as IFN-γ/STAT1 were associated with HER-2.

Conclusion

HER-2 status could predict the efficacy of immune checkpoint inhibitors, and HER-2 status combined with PD-L1 level could predict the prognosis of GC patients.

T Cells in Chronic Lymphocytic Leukemia: A Two-Edged Sword

Chronic lymphocytic leukemia (CLL) is a malignancy of mature, antigen-experienced B lymphocytes. Despite great progress recently achieved in the management of CLL, the disease remains incurable, underscoring the need for further investigation into the underlying pathophysiology. Microenvironmental crosstalk has an established role in CLL pathogenesis and progression. Indeed, the malignant CLL cells are strongly dependent on interactions with other immune and non-immune cell populations that shape a highly orchestrated network, the tumor microenvironment (TME). The composition of the TME, as well as the bidirectional interactions between the malignant clone and the microenvironmental elements have been linked to disease heterogeneity. Mounting evidence implicates T cells present in the TME in the natural history of the CLL as well as in the establishment of certain CLL hallmarks e.g. tumor evasion and immune suppression. CLL is characterized by restrictions in the T cell receptor gene repertoire, T cell oligoclonal expansions, as well as shared T cell receptor clonotypes amongst patients, strongly alluding to selection by restricted antigenic elements of as yet undisclosed identity. Further, the T cells in CLL exhibit a distinctive phenotype with features of “exhaustion” likely as a result of chronic antigenic stimulation. This might be relevant to the fact that, despite increased numbers of oligoclonal T cells in the periphery, these cells are incapable of mounting effective anti-tumor immune responses, a feature perhaps also linked with the elevated numbers of T regulatory subpopulations. Alterations of T cell gene expression profile are associated with defects in both the cytoskeleton and immune synapse formation, and are generally induced by direct contact with the malignant clone. That said, these abnormalities appear to be reversible, which is why therapies targeting the T cell compartment represent a reasonable therapeutic option in CLL. Indeed, novel strategies, including CAR T cell immunotherapy, immune checkpoint blockade and immunomodulation, have come to the spotlight in an attempt to restore the functionality of T cells and enhance targeted cytotoxic activity against the malignant clone.

Tumor β-catenin expression is associated with immune evasion in non-small cell lung cancer with high tumor mutation burden

β-catenin expression by tumor cells suppressed dendritic cell recruitment to the tumor microenvironment in a melanoma model, resulting in fewer tumor-infiltrating lymphocytes. Immunohistochemistry was used in the present study to examine the association between the expression of β-catenin and tumor infiltrating lymphocytes and CD11c⁺ cells in 122 patients with non-small cell lung cancer (NSCLC), who underwent radical surgery. β-catenin was positive in 24% of NSCLC tumors compared with 59% of squamous cell carcinomas and 11% of adenocarcinomas. There was no significant association between the expression of β-catenin and the frequency of CD8⁺ cell infiltration into tumor tissues, including the stroma. Conversely, the infiltration of CD8⁺ cells into tumor nests was significantly lower in β-catenin-positive cases compared with that in negative β-catenin cases. Similarly, CD11c⁺ cell infiltration was significantly lower in the β-catenin-positive group. The β-catenin-positive group had shorter overall survival and recurrence-free survival times compared with that in the negative group. Furthermore, β-catenin-positive NSCLC had a high tumor mutation burden, but tended to have a low expression of programmed death-ligand 1. In conclusion, the expression of β-catenin in NSCLC was negatively associated with CD11c⁺ cells and cytotoxic T cell infiltration at the tumor site and had a tendency towards a poor prognosis.

Design, synthesis and evaluation of PD-L1 peptide antagonists as new anticancer agents for immunotherapy

Blocking the interaction of programmed cell death protein 1 (PD-1) and its ligand PD-L1 is known as a promising immunotherapy for treatment of a variety of tumors expressing PD-L1 on their cell surface. In the last decade, several antibodies against the PD-1/PD-L1 interaction have been approved, while there are few reports of small-molecule inhibitors against PD-1/PD-L1 axis. Due to many advantages of cancer treatment with small molecules over antibodies, we developed several peptidic PD-L1 antagonists using computational peptide design methods, and evaluated them both in vitro and in vivo. Importantly, among six peptides with best affinity to PD-L1, four peptides exhibited significant potency to block PD-1/PD-L1 axis at molecular level. Moreover, the PD-L1 expression in nine human colorectal cancer cell lines stimulated with interferon-γ was compared and LoVo cells with the highest expression were selected for further experiments. The peptides could also restore the function of activated Jurkat T cells, which had been suppressed by stimulated LoVo cells. A blockade assay in tumor-bearing mice experiments indicated that peptides HS5 and HS6 consisting of a d-amino acid in their structures, could also effectively reduce tumor growth in vivo, without induction of any observable liver or renal toxicity, tissue damages and loss of body weight. As new designed peptides showed no toxicity against murine colon cancer cells in vitro, the observed anti-tumor results in mice are most probably due to disrupting the PD-1/PD-L1 interaction. Thus, peptides described in this study can be considered as proper low molecular weight candidates for immunotherapy of cancer.

Targeting the PD-1/PD-L1 Axis in Human Vitiligo

Autoreactive CD8⁺ T cells play a pivotal role in melanocyte destruction in autoimmune vitiligo. Immunotherapy for melanoma often leads to autoimmune side-effects, among which vitiligo-like depigmentation, indicating that targeting immune checkpoints can break peripheral tolerance against self-antigens in the skin. Therapeutically enhancing immune checkpoint signaling by immune cells or skin cells, making self-reactive T cells anergic, seems a promising therapeutic option for vitiligo. Here, we review the current knowledge on the PD-1/PD-L1 pathway in vitiligo as new therapeutic target for vitiligo therapy.

Targeting TIM-3 in solid tumors: innovations in the preclinical and translational realm and therapeutic potential

INTRODUCTION

Immune checkpoint inhibitors (ICIs) have shown a great therapeutic efficacy in cancer patients. However, a significant proportion of cancer patients remain unresponsive or show limited response. T cell immunoglobulin and mucin-domain containing protein-3 (TIM-3) is a co-inhibitory receptor expressed on various cell types and is involved in the attenuation of immune responses. TIM-3 and its ligands are highly expressed in various solid malignancies and some studies have reported its association with worse disease outcomes. Thus, targeting TIM-3 could be a promising therapeutic approach to treat cancer patients.

AREAS COVERED

This review describes the role of TIM-3 and its ligands in regulating anti-tumor immunity and their contribution to cancer progression. Moreover, this review focuses on the preclinical models and translational data from important studies published in PubMed till October 2020, which demonstrate the therapeutic benefits of targeting TIM-3 signaling.

EXPERT OPINION

Despite the promising data obtained from targeting TIM-3 in preclinical models, precise mechanisms underlying the anti-tumor effects of TIM-3 inhibition are not fully elucidated. Therefore, mechanistic studies are required to provide better insights into the anti-tumor effects of targeting TIM-3, and clinical data are necessary to determine the safety profiles and therapeutic efficacy of TIM-3 inhibition in cancer patients.

PD-L1 Detection-Pearls and Pitfalls Associated With Current Methodologies Focusing on Entities Relevant to Dermatopathology

PD-L1 is a transmembrane glycoprotein with an extracellular as well as an intracellular cytoplasmic domain. Physiologically, it plays a pivotal role in regulating T-cell activation and tolerance. Many tumor cells have exploited this regulatory mechanism by overexpressing PD-L1 in an effort to escape immunologic surveillance. In this review, we parse the literature regarding the prognostic value of tumoral PD-L1 expression before discussing the various methodologies as well as the pearls and pitfalls associated with each for predicting response to anti-PD-1/PD-L1 therapies. Special attention is given to cutaneous entities in which PD-L1 expression has been documented with an emphasis on cutaneous malignancies that have seen the broadest applications of anti-PD-L1/PD-1 therapies. Currently, immunohistochemistry is the method that is most commonly used for detection of PD-L1. However, with the wide array of immunohistochemistry protocols and staining platforms available in the market, there seems to be different cutoffs not just for different entities but also for the same entity. This review is an attempt to address the need for standardization and validation of existing protocols for PD-L1 detection.

Immunosurveillance and Immunoediting of Lung Cancer: Current Perspectives and Challenges

The immune system plays a dual role in tumor evolution-it can identify and control nascent tumor cells in a process called immunosurveillance and can promote tumor progression through immunosuppression via various mechanisms. Thus, bilateral host-protective and tumor-promoting actions of immunity are integrated as cancer immunoediting. In this decade, immune checkpoint inhibitors, specifically programmed cell death 1 (PD-1) pathway inhibitors, have changed the treatment paradigm of advanced non-small cell lung cancer (NSCLC). These agents are approved for the treatment of patients with NSCLC and demonstrate impressive clinical activity and durable responses in some patients. However, for many NSCLC patients, the efficacy of immune checkpoint inhibitors is limited. To optimize the full utility of the immune system for eradicating cancer, a broader understanding of cancer immunosurveillance and immunoediting is essential. In this review, we discuss the fundamental knowledge of the phenomena and provide an overview of the next-generation immunotherapies in the pipeline.

Targeting Cancer with Genetically Engineered TCR T Cells

The adoptive cell transfer (ACT) of genetically engineered T cell receptor (TCR) T cells is one of the burgeoning fields of immunotherapy, with promising results in current clinical trials. Presently, clinicaltrials.gov has over 200 active trials involving adoptive cell therapy. The ACT of genetically engineered T cells not only allows the ability to select for TCRs with desired properties such as high-affinity receptors and tumor reactivity but to further enhance those receptors allowing for better targeting and killing of cancer cells in patients. Moreover, the addition of genetic material, including cytokines and cytokine receptors, can increase the survival and persistence of the T cell allowing for complete and sustained remission of cancer targets. The potential for improvement in adoptive cell therapy is limitless, with genetic modifications targeting to improve weaknesses of ACT and to thus enhance receptor affinity and functional avidity of the genetically engineered T cells.

PD-L1, PD-1, LAG-3, and TIM-3 in Melanoma: Expression in Brain Metastases Compared to Corresponding Extracranial Tumors

Background

Metastatic melanoma to the brain carries a particularly poor prognosis that may be associated with an attenuated antitumor response in the presence of central nervous system malignancies. Thus, the development of brain metastases could theoretically accelerate cancer progression both locally and systemically. Although dysregulation of checkpoint markers, such as programmed death-ligand 1 (PD-L1), programmed cell death receptor 1 (PD-1), lymphocyte activation gene 3 (LAG-3), and T-cell immunoglobulin and mucin-domain containing-3 (TIM-3), have been implicated in immune dysfunction, the exact relationship between these markers and brain tumor-mediated immune suppression remains unclear. Thus, the objective of this study was to explore whether there exists a differential expression of the above checkpoint markers in the intracranial milieu as compared to tumors in the periphery, which may shed light on the mechanism behind the diminished antitumor response.

Methods

We identified nine patients with extracranial melanomas and matched intracranial metastases. Formalin-fixed, paraffin-embedded slides were stained for PD-L1, PD-1, LAG-3, and TIM-3 via immunohistochemistry. Qualitative analysis was performed to assess the staining of the markers in the neoplastic and lymphocytic cells, which were the two cell lineages in each biopsy. 

Results

Expression of PD-1 and TIM-3 between extracranial and intracranial tumoral sites was conserved. Specifically, in lymphocytes, PD-1 expression was observed in 100% of extracranial and 100% of intracranial slides, whereas TIM-3 expression was seen in 33.33% of extracranial and 33.33% of intracranial slides. Neither marker stained tumor cells, as expected. PD-L1 showed a slight variation in staining between sites, with lymphocyte staining in 100% of extracranial and 88.89% of intracranial slides, and the same percentages per site for tumor cells. The greatest variability was observed in LAG-3 lymphocyte staining, with staining in 77.78% of extracranial and 33.33% of intracranial slides. No LAG-3 staining of tumor cells was noted, as expected.

Conclusion

Preliminary analysis revealed the conservation of PD-L1, PD-1, LAG-3, and TIM-3 expression intra- and extracranially. This could suggest that these markers are important in maintaining an immunosuppressive phenotype at both sites. Another possibility is that this pattern of expression is associated with patients who develop brain metastasis, as this was the only subset of patients included in this study. Interestingly, LAG-3 staining of lymphocytes appeared more prominent in extracranial over intracranial tumors. Future studies should include more samples to draw out potential patterns masked by the small sample size, as well as to compare checkpoint expression in other patient groups, such as those with non-brain metastasis or those with no metastasis at all.

Emerging therapeutic approaches for canine sarcomas: Pushing the boundaries beyond the conventional

Sarcomas represent a group of genomically chaotic, highly heterogenous tumours of mesenchymal origin with variable mutational load. Conventional therapy with surgery and radiation therapy is effective for managing small, low-grade sarcomas and remains the standard therapeutic approach. For advanced, high-grade, recurrent, or metastatic sarcomas, systemic chemotherapy provides minimal benefit, therefore, there is a drive to develop novel approaches. The discovery of "Coley's toxins" in the 19th century, and their use to stimulate the immune system supported the application of unconventional therapies for the treatment of sarcomas. While promising, this initial work was abandoned and treatment paradigm and disease course of sarcomas was largely unchanged for several decades. Exciting new therapies are currently changing treatment algorithms for advanced carcinomas and melanomas, and similar approaches are being applied to advance the field of sarcoma research. Recent discoveries in subtype-specific cancer biology and the identification of distinct molecular targets have led to the development of promising targeted strategies with remarkable potential to change the landscape of sarcoma therapy in dogs. The purpose of this review article is to describe the current standard of care and limitations as well as emerging approaches for sarcoma therapy that span many of the most active paradigms in oncologic research, including immunotherapies, checkpoint inhibitors, and drugs capable of cellular metabolic reprogramming.

Noncoding RNAs as potential mediators of resistance to cancer immunotherapy

Substantial evolution in cancer therapy has been witnessed lately, steering mainly towards immunotherapeutic approaches, replacing or in combination with classical therapies. Whereas the use of various immunotherapy approaches, such as adoptive T cell therapy, genetically-modified T cells, or immune checkpoint inhibitors, has been a triumph for cancer immunotherapy, the great challenge is the ability of the immune system to sustain long lasting anti-tumor response. Additionally, epigenetic changes in a suppressive tumor microenvironment can pertain to T cell exhaustion, limiting their functionality. Noncoding RNAs (ncRNAs) have emerged over the last years as key players in epigenetic regulation. Among those, microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) have been studied extensively for their potential role in regulating tumor immunity through direct regulation of genes involved in immune activation or suppression. In this review, we will provide an overview of contemporary approaches for cancer immunotherapy and will present the current state of knowledge implicating miRNAs and lncRNAs in regulating immune response against human cancer and their potential implications in resistance to cancer immunotherapy, with main emphasis on immune checkpoints regulation.

miR-149-3p reverses CD8+ T-cell exhaustion by reducing inhibitory receptors and promoting cytokine secretion in breast cancer cells

Blockade of inhibitory receptors (IRs) is one of the most effective immunotherapeutic approaches to treat cancer. Dysfunction of miRNAs is a major cause of aberrant expression of IRs and contributes to the immune escape of cancer cells. How miRNAs regulate immune checkpoint proteins in breast cancer remains largely unknown. In this study, downregulation of miRNAs was observed in PD-1-overexpressing CD8⁺ T cells using miRNA array analysis of mouse breast cancer homografts. The data reveal that miR-149-3p was predicted to bind the 3'UTRs of mRNAs encoding T-cell inhibitor receptors PD-1, TIM-3, BTLA and Foxp1. Treatment of CD8⁺ T cells with an miR-149-3p mimic reduced apoptosis, attenuated changes in mRNA markers of T-cell exhaustion and downregulated mRNAs encoding PD-1, TIM-3, BTLA and Foxp1. On the other hand, T-cell proliferation and secretion of effector cytokines indicative of increased T-cell activation (IL-2, TNF-α, IFN-γ) were upregulated after miR-149-3p mimic treatment. Moreover, the treatment with a miR-149-3p mimic promoted the capacity of CD8⁺ T cells to kill targeted 4T1 mouse breast tumour cells. Collectively, these data show that miR-149-3p can reverse CD8⁺ T-cell exhaustion and reveal it to be a potential antitumour immunotherapeutic agent in breast cancer.

Therapeutic PD-L1 antibodies are more effective than PD-1 antibodies in blocking PD-1/PD-L1 signaling

Inhibitors of PD-1 signaling have revolutionized cancer therapy. PD-1 and PD-L1 antibodies have been approved for the treatment of cancer. To date, therapeutic PD-1 inhibitors have not been compared in a functional assay. We used an efficient T cell reporter platform to evaluate the efficacy of five clinically used PD-1 inhibitors to block PD-1 signaling. The half maximal effective concentrations (EC50) for nivolumab and pembrolizumab were 76.17 ng/ml (95% CI 64.95-89.34 ng/ml) and 39.90 ng/ml (34.01-46.80 ng/ml), respectively. The EC50 values of the PD-L1 inhibitors were 6.46 ng/ml (5.48-7.61 ng/ml), 6.15 ng/ml (5.24-7.21 ng/ml) and 7.64 ng/ml (6.52-8.96 ng/ml) for atezolizumab, avelumab, and durvalumab, respectively. In conclusion, a functional assay evaluating antibodies targeting PD-1 inhibition in vitro revealed that pembrolizumab is a slightly more effective PD-1 blocker than nivolumab, and that PD-L1 antibodies are superior to PD-1 antibodies in reverting PD-1 signaling.

A carrier-free multiplexed gene editing system applicable for suspension cells

Genetically engineered cells via CRISPR/Cas9 system can serve as powerful sources for cancer immunotherapeutic applications. Furthermore, multiple genetic alterations are necessary to overcome tumor-induced immune-suppressive mechanisms. However, one of the major obstacles is the technical difficulty with efficient multiple gene manipulation of suspension cells due to the low transfection efficacy. Herein, we established a carrier-free multiplexed gene editing platform in a simplified method, which can enhance the function of cytotoxic CD8⁺ T cells by modulating suspension cancer cells. Our multiple Cas9 ribonucleoproteins (RNPs) enable simultaneous disruption of two programmed cell death 1 (PD-1) ligands, functioning as negative regulators in the immune system, by accessing engineered Cas9 proteins with abilities of complexation and cellular penetration. In addition, combination with electroporation enhanced multiple gene editing efficacy, compared with that by treatment of multiple Cas9 RNPs alone. This procedure resulted in high gene editing at multiple loci of suspension cells. The treatment of multiple Cas9 RNPs targeting both ligands strongly improved Th1-type cytokine production of cytotoxic CD8⁺ T cells, resulting in synergistic cytotoxic effects against cancer. Simultaneous suppression of PD-L1 and PD-L2 on cancer cells via our developed editing system allows effective anti-tumor immunity. Furthermore, the treatment of multiple Cas9 RNPs targeting PD-L1, PD-L2, and TIM-3 had approximately 70-90% deletion efficacy. Thus, our multiplexed gene editing strategy endows potential clinical utilities in cancer immunotherapy.

Plasma soluble programmed death ligand 1 levels predict clinical response in peripheral T-cell lymphomas

Immune checkpoints, including PD-1/PD-L1, play an important role in immunosuppression in various malignancies. Elevated levels of soluble programmed death ligand 1 (sPD-L1) are associated with worse prognosis in multiple myeloma and diffuse large B cell lymphoma. Herein, the purpose of this study is to investigate the relationships between plasma sPD-L1 levels and clinical response in peripheral T-cell lymphoma (PTCL) patients. A total of 37 PTCL patients and 20 healthy volunteers were enrolled. Peripheral blood from patients was collected prior to systemic therapy. Plasma levels of sPD-L1 and IFN-γ were measured by enzyme-linked immunosorbent assay (ELISA). PD-L1 expression in tissues was detected by immunohistochemistry (IHC). Clinical response for patients was evaluated. ONCOMINE database analyses showed that PD-L1 mRNA expression was significantly upregulated in PTCLs. The median sPD-L1 level was 0.729 ng/mL for 20 healthy volunteers and 1.696 ng/mL for 37 PTCL patients which was significantly higher than that in healthy volunteers (0.000). The sPD-L1 level was positively correlated with IFN-γ level (0.000, r = 0.849) and was also positively associated with clinical staging (0.045), LDH level (0.003), and β2-MG level (0.045). Patients with high sPD-L1 level had lower overall response rate than those with low sPD-L1 level (88.9% vs 50.0%, 0.022) and tended to have poorer PFS and OS. PD-L1 expression in tissues matched very well with the sPD-L1 level in PTCL patients. In conclusion, PTCL patients had higher sPD-L1 level compared with healthy volunteers. High sPD-L1 level was correlated with worse clinical response, suggesting that sPD-L1 level was an underlying plasma biomarker to predict the prognosis for PTCL patients.

PD-L1 checkpoint blockade delivered by retroviral replicating vector confers anti-tumor efficacy in murine tumor models

Immune checkpoint inhibitors (CPIs) are associated with a number of immune-related adverse events and low response rates. We provide preclinical evidence for use of a retroviral replicating vector (RRV) selective to cancer cells, to deliver CPI agents that may circumvent such issues and increase efficacy. An RRV, RRV-scFv-PDL1, encoding a secreted single chain variable fragment targeting PD-L1 can effectively compete with PD-1 for PD-L1 occupancy. Cell binding assays showed trans-binding activity on 100% of cells in culture when infection was limited to 5% RRV-scFv-PDL1 infected tumor cells. Further, the ability of scFv PD-L1 to rescue PD-1/PD-L1 mediated immune suppression was demonstrated in a co-culture system consisting of human-derived immune cells and further demonstrated in several syngeneic mouse models including an intracranial tumor model. These tumor models showed that tumors infected with RRV-scFv-PD-L1 conferred robust and durable immune-mediated anti-tumor activity comparable or superior to systemically administered anti-PD-1 or anti PD-L1 monoclonal antibodies. Importantly, the nominal level of scFv-PD-L1 detected in serum is ∼50–150 fold less than reported for systemically administered therapeutic antibodies targeting immune checkpoints. These results support the concept that RRV-scFv-PDL1 CPI strategy may provide an improved safety and efficacy profile compared to systemic monoclonal antibodies of currently approved therapies.