Traditional Chinese medicine in the era of immune checkpoint inhibitor: theory, development, and future directions

Tetrahydrocurcumin-induced apoptosis of hepatocellular carcinoma cells involves the TP53 signaling pathway, as determined by network pharmacology

BACKGROUND

Hepatocellular carcinoma (HCC) is a malignant disease with high incidence and mortality worldwide. This study focuses on the TP53 target protein to investigate the potential therapeutic effect of tetrahydrocurcumin (THC) on HCC and its mechanism of action. The research hypothesis is that THC can inhibit the proliferation, migration, and invasion of HCC cells, and promote their apoptosis by regulating the TP53 target protein.

AIM

To explore the mechanism by which THC inhibits HCC cell proliferation via the TP53 signaling pathway.

METHODS

Potential targets of THC and HCC were identified from multiple databases. The core targets were subjected to analyses using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases, and visualization processing, using the online platform Metascape to identify the key molecules and signaling pathways involved in the action of THC against HCC. The molecular mechanisms of action of THC against TP53 in the inhibition of HCC cells were verified using cell counting kit-8, Transwell, apoptosis, and western blotting assays.

RESULTS

Molecular docking results showed that THC had a high score for the TP53 target protein. In vitro experiments indicated that THC effectively inhibited the proliferation and migration of HCC cells, and affected the expression levels of TP53, MDM2, cyclin B, Bax, Bcl-2, caspase-9, and caspase-3.

CONCLUSION

THC induces the apoptosis of HCC cells through the TP53 signaling pathway, thereby inhibiting their proliferation and migration.

Drug functional remapping: a new promise for tumor immunotherapy

The research and development of new anti-cancer drugs face challenges such as high costs, lengthy development cycles, and limited data on side effects. In contrast, the clinical safety and side effects of traditional drugs have been well established through long-term use. The development or repurposing of traditional drugs with potential applications in cancer treatment offers an economical, feasible, and promising strategy for new drug development. This article reviews the novel applications of traditional drugs in tumor immunotherapy, discussing how they can enhance tumor treatment efficacy through functional repositioning, while also reducing development time and costs. Recent advancements in cancer immunotherapy have revolutionized treatment options, but resistance to ICIs remains a significant challenge. Drug repurposing has emerged as a promising strategy to identify novel agents that can enhance the efficacy of immunotherapies by overcoming ICI resistance. A study suggests that drug repositioning has the potential to modulate immune cell activity or alter the tumor microenvironment, thereby circumventing the resistance mechanisms associated with immune checkpoint blockade. This approach provides a rapid and cost-effective pathway for identifying therapeutic candidates that can be quickly transitioned into clinical trials. To improve the effectiveness of tumor immunotherapy, it is crucial to explore systematic methods for identifying repurposed drug candidates. Methods such as high-throughput screening, computational drug repositioning, and bioinformatic analysis have been employed to efficiently identify potential candidates for cancer treatment. Furthermore, leveraging databases related to immunotherapy and drug repurposing can provide valuable resources for drug discovery and facilitate the identification of promising compounds. It focuses on the latest advancements in the use of antidiabetic drugs, antihypertensive agents, weight-loss medications, antifungal agents, and antiviral drugs in tumor immunotherapy, examining their mechanisms of action, clinical application prospects, and associated challenges. In this context, our aim is to explore these strategies and highlight their potential for expanding the therapeutic options available for cancer immunotherapy, providing valuable references for cancer research and treatment.

Evaluation of efficacy, safety and underlying mechanism on Traditional Chinese medicine as synergistic agents for cancer immunotherapy: A preclinical systematic review and meta-analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Based on the documentation in Shennong's Herbal Classics, numerous Traditional Chinese medicine (TCM) are noted to possess anti-tumor properties, and TCM has been used in China for thousands of years. Particularly, current research have demonstrated that TCM combined with immunotherapy exhibited enhanced anti-tumor effects.

AIM OF THE STUDY

This meta-analysis aimed to evaluate the effectiveness, security, and potential mechanisms of TCM coupled with programmed cell death protein-1/programmed death ligand-1 (PD-1/PD-L1) inhibitors in cancer animal models.

MATERIALS AND METHODS

The pertinent research was performed in English database including PubMed, Web of Science, Embase, and Cochrane Library, as well as Chinese database including China National Knowledge Infrastructure (CNKI) and Wanfang Data Database published until January 2024. The quality of the included studies was evaluated with Systematic Review Center for Laboratory animal Experimentation (SYRCLE) risk assessment tool, and statistical analysis was conducted with Revman 5.4 software. Egger's test and funnel plots were used to assess potential publication bias.

RESULTS

An aggregate of 30 articles comprising 39 studies fulfilled the conditions for examination. The meta-analysis revealed that TCM + PD-1/PD-L1 inhibitors exhibited significant effects in inhibiting tumor growth (standard mean difference (SMD) = -2.61, 95% confidence interval (CI) = [-3.15, -2.07]), reducing tumor weight [SMD = -2.79 (-3.75, -1.83)], prolonging the survival time, and enhancing immune function in both cellular (CD4+ T cell percentage: 3.00 [1.45, 4.55]; CD8+ T cell percentage: 3.06 [2.16, 3.95]) and humoral immunity (interferon-γ (IFN-γ): 3.43, [2.54, 4.32]; tumor necrosis factor-α (TNF-α): 2.78 [1.46, 4.09]; interleukin (IL)-2: 1.79, [0.62, 2.95]; IL-6: 2.34, [0.07, 4.60]), and the differences between the two groups of the above indicators were statistically significant. No significant difference was found for aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels. The mechanisms of TCM impacting PD-1/PD-L1 inhibitors therapy were closely associated with regulating tumor microenvironment, modulating gut microbiota, suppressing expression of PD-1 or PD-L1, and regulating cytokine signaling.

CONCLUSION

TCM displayed a potential enhanced anti-tumor efficacy of PD-1/PD-L1 inhibitors on six types of tumor including colon, breast, colorectal, melanoma, and bladder cancer in animals. However, due to significant heterogeneity in the included studies, caution should be exercised regarding the results. More high-quality randomized controlled animal experiments are need.

Traditional Chinese medicine enhances the effectiveness of immune checkpoint inhibitors in tumor treatment: A mechanism discussion

ETHNOPHARMACOLOGICAL RELEVANCE

Immune checkpoint inhibitors (ICIs) have altered the landscape of tumor immunotherapy, offering novel therapeutic approaches alongside surgery, chemotherapy, and radiotherapy and significantly improving survival benefits. However, their clinical efficacy is limited in some patients, and their use may cause immune-related adverse events (irAEs). Integrating traditional Chinese medicine (TCM) with ICIs has demonstrated the potential to boost sensitization and reduce toxicity. Clinical trials and experimental explorations have confirmed that TCM and its active components synergistically enhance the effectiveness of ICIs.

AIMS

This narrative review summarizes the TCM practices that enhance the clinical efficacy and reduce irAEs of ICIs. This paper also summarizes the mechanism of experimental studies on the synergies of Chinese herbal decoctions, Chinese herbal preparation, and Chinese herbal active ingredients. Most of the studies on TCM combined with ICIs are basic experiments. We discussed the mechanism of TCM enhanced ICIs to provide reference for the research and development of TCM adjuvant immunotherapy.

METHODS

We conducted a literature search using PubMed and Chinese National Knowledge Infrastructure databases, with a focus on herbal decoction, Chinese medicine preparations, and active ingredients that boost the effectiveness of ICIs and reduce irAEs. The search keywords were "ICIs and traditional Chinese medicine", "PD-1 and traditional Chinese medicine", "PD-L1 and traditional Chinese medicine", "CTLA-4 and traditional Chinese medicine", "IDO1 and traditional Chinese medicine", "Tim-3 and traditional Chinese medicine", "TIGIT and traditional Chinese medicine", "irAEs and traditional Chinese medicine". The search period was from May 2014 to May 2024. Articles involving the use of TCM or its components in combination with ICIs and investigating the underlying mechanisms were screened. Finally, 30 Chinese medicines used in combination with ICIs were obtained to explore the mechanism. In the part of immune checkpoint molecules other than PD-1, there were few studies on the combined application of TCM, so studies involving the regulation of immune checkpoint molecules by TCM were included.

RESULTS

TCM has been shown to boost the effectiveness of ICIs and reduce irAEs. Researchers indicate that TCM and its active components can work synergistically with ICIs by regulating immune checkpoints PD-1, PD-L1, CTLA-4, and IDO1, regulating intestinal flora, improving tumor microenvironment and more.

CONCLUSIONS

Combining TCM with ICIs can play a better anti-tumor role, but larger samples and high-quality clinical trials are necessary to confirm this. Many Chinese medicines and their ingredients have been shown to sensitize ICIs in experimental studies, which provides a rich choice for the subsequent development of ICI enhancers.

Mechanistic insights into the role of traditional Chinese medicine in treating gastric cancer

Gastric cancer remains a leading cause of cancer-related mortality worldwide, with advanced stages presenting significant challenges due to metastasis and drug resistance. Traditional Chinese Medicine (TCM) offers a promising complementary approach characterized by holistic treatment principles and minimal side effects. This review comprehensively explores the multifaceted mechanisms by which TCM addresses gastric cancer. Specifically, we detail how TCM inhibits aerobic glycolysis by downregulating key glycolytic enzymes and metabolic pathways, thereby reducing the energy supply essential for cancer cell proliferation. We examine how TCM suppresses angiogenesis by targeting the vascular endothelial growth factor (VEGF) and cyclooxygenase-2 (COX-2) pathways, effectively starving tumors of nutrients and oxygen required for growth and metastasis. Furthermore, TCM modulates the immune microenvironment by enhancing the activity of effector immune cells such as CD4+ and CD8+ T cells and natural killer (NK) cells while reducing immunosuppressive cells like regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs). These actions collectively contribute to slowing tumor progression, inhibiting metastasis, and enhancing the body's antitumor response. The insights presented underscore the significant potential of TCM as an integral component of comprehensive gastric cancer treatment strategies, highlighting avenues for future research and clinical application to improve patient outcomes.

Efficacy and Safety of Herbal Medicine Bojungikki-Tang in Combination with Pembrolizumab versus Pembrolizumab Monotherapy for Stage IV Non-Small Cell Lung Cancer: Study Protocol for a Randomized, Open-Label, Double-Arm, Multicenter Trial

BACKGROUND

Non-small cell lung cancer (NSCLC) exhibits low survival rates. Although immune checkpoint inhibitors (ICIs) have become first-line treatment for NSCLC, their limited response to ICI monotherapy has led to exploration of combination treatments. However, the high incidence of treatment-related adverse events associated with conventional drug combinations has highlighted the need for alternative herbal therapy. Bojungikki-tang (BJIKT), a traditional herbal medicine, has been used to treat gastrointestinal disorders and enhance immune function. Our preclinical studies have demonstrated that BJIKT combined with anti-PD-1 or anti-PD-L1 antibodies exhibits significant efficacy in suppressing tumor growth by modulating the immunosuppressive tumor microenvironment. Building on these preclinical findings, this study aims to evaluate the efficacy and safety of BJIKT with pembrolizumab combination therapy compared to pembrolizumab monotherapy in advanced NSCLC patients.

METHODS

70 individuals with stage IV NSCLC scheduled for first-line pembrolizumab monotherapy will be randomly assigned to intervention or control groups. The primary outcome will be progression-free survival, with secondary outcomes including disease control rate, overall survival, and quality of life assessment. Adverse events will be monitored for safety. This study will explore the synergistic mechanism of combinatorial therapy using immune profiling and multi-omics analysis, and the possibility for personalized integrative therapy based on cold-heat syndrome differentiation (SD) types in East Asian medicine.

DISCUSSION

This study will provide novel evidence regarding survival outcomes, quality of life, and safety profiles of combined ICI and BJIKT therapy for advanced NSCLC. The exploratory data will contribute to tailoring treatments to immune-based SD types in NSCLC patients.

The Role of Zuo Jin Wan in Modulating the Tumor Microenvironment of Colorectal Cancer

INTRODUCTION

Traditional Chinese medicine (TCM) can modulate the immune function of tumor patients in various ways. Zuojin Wan (ZJW, a 6:1 ratio of Huang Lian and Wu Zhu Yu) can modulate the microenvironment of ulcerative colitis, but its role in regulating the colorectal cancer (CRC) microenvironment remains unclear. Exploring the role of ZJW in CRC immunomodulation may improve the antitumor effect of existing immunotherapeutic strategies.

MATERIAL AND METHODS

The active compounds of each herb in ZJW were obtained from the HIT2.0 database with literature evidence. Single-cell RNA sequencing data of CRC were obtained from published studies (PMID: 32451460, 32103181, and 32561858). Pathway enrichment was analyzed using the reactome database, and intergenic correlation analysis was performed using the corrplot R software package. ZJW-regulated gene expression was verified by RT-qPCR.

RESULTS

Huang Lian and Wu Zhu Yu contain 19 and 4 compounds, respectively. Huang Lian targets 146 proteins, and Wu Zhu Yu targets 28 proteins based on evidence from the literature. ZJW regulates a range of biological processes associated with immune function, including cytokine signaling and Toll-Like Receptor 4 (TLR4) cascade. ZJW regulates malignant CRC cells, immune cells (including T-cells, B-cells, mast cells, NK/NKT cells, and myeloid cells), and other nonimmune cells (including endothelial cells, enteric glial cells, and pericytes). We confirmed that ZJW significantly downregulated the expression of TIMP1 and MTDHin CRC cell lines.

CONCLUSIONS

ZJW regulates a range of cells in the CRC microenvironment, including malignant CRC, immune cells, and stromal cells. In CRC cell lines, downregulation of TIMP1 and MTDH by ZJW may play an important role in the immunomodulation in CRC.

Chinese Medicine in Colorectal Cancer Treatment: From Potential Targets and Mechanisms to Clinical Application

Colorectal cancer (CRC) is a global health challenge necessitating innovative therapeutic strategies. There is an increasing trend toward the clinical application of integrative Chinese medicine (CM) and Western medicine approaches. Chinese herbal monomers and formulations exert enhanced antitumor effects by modulating multiple signaling pathways in tumor cells, including inhibiting cell proliferation, inducing apoptosis, suppressing angiogenesis, reversing multidrug resistance, inhibiting metastasis, and regulating immunity. The synergistic effects of CM with chemotherapy, targeted therapy, immunotherapy, and nanovectors provide a comprehensive framework for CRC treatment. CM can mitigate drug toxicity, improve immune function, control tumor progression, alleviate clinical symptoms, and improve patients' survival and quality of life. This review summarizes the key mechanisms and therapeutic strategies of CM in CRC, highlighting its clinical significance. The potential for CM and combination with conventional treatment modalities is emphasized, providing valuable insights for future research and clinical practice.

Therapeutic and immunomodulatory effects of Bojungikki-tang on cancer: a scoping review

BACKGROUND

Cancer remains a major global health concern, with conventional treatments often limited by side effects and resistance. Bojungikki-tang (BJIKT), a traditional herbal formula, has shown promise in alleviating cancer-related symptoms and enhancing anti-cancer effects when combined with conventional treatments. As immune checkpoint inhibitors (ICIs) have become the standard for cancer treatment, a combination of BJIKT and ICIs may exhibit immune-mediated anti-cancer effects. This review aims to summarize the recent evidence on BJIKT use in cancer treatment, investigate its immunomodulatory effects, and identify research gaps.

METHODS

This review was conducted and reported following the Arksey and O'Malley framework and the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Scoping Review. A comprehensive search of six electronic databases was conducted, and studies published between 2013 and 2022 were identified. Reports on oral administration of BJIKT to patients with cancer were included and analyzed by two reviewers. The extracted data were synthesized using descriptive reporting and meta-analysis.

RESULTS

Overall, 56 studies met the inclusion criteria: 36 human studies, 14 experimental studies, and 6 reviews on clinical and preclinical investigations. The use of BJIKT in restoring immune function and improving fatigue, cancer-related fever, and quality of life after chemotherapy has been reported in clinical studies. The different medication forms of BJIKT included decoction, extract granules, pills, and water extract. The meta-analysis revealed a significantly higher Karnofsky Performance Scale score in the BJIKT plus chemotherapy group than in the chemotherapy alone group. Preclinical studies have demonstrated that BJIKT has anti-cancer effects, enhances gastrointestinal function and immunomodulatory effects, and supports favorable chemotherapy outcomes.

CONCLUSION

In recent clinical research on BJIKT, its impact on fatigue, quality of life, and alleviating cancer-related fever has mostly been examined. The direct anti-cancer activities and immunomodulatory mechanisms of BJIKT have been reported in preclinical studies; however, clinical research on BJIKT-induced enhancement of immune function is lacking. Further research on the efficacy and safety of ICI combined with BJIKT and the association of immunomarker changes with clinical outcomes is required to precisely identify the effect of BJIKT on immune system modulation.

Curcumin affects autophagy of prolactinoma cells by upregulating miR-206 to exert antitumor effects

We explored the effects of curcumin on the aberrant biological behaviors of prolactinoma cells and the downstream pathways through which curcumin exerts its antitumor effects. We used quantitative reverse transcription-polymerase chain reaction assays to measure miR-206 expression levels in peripheral blood samples from patients with prolactinoma before and after curcumin treatment. We also investigated the proliferation level, viability, and invasion ability of groups of cells treated with different concentrations of curcumin using 3-(4,5)-dimethylthiahiazo (-z-y1)-3-di-phenytetrazoliumromide (MTT) assays, cell cloning assays, and Transwell assays, respectively. Furthermore, we determined the levels of autophagy-related proteins and protein kinase B/mammalian target of the rapamycin (Akt/mTOR) signaling pathway-related proteins in each group of treated cells by western blot. Curcumin treatment upregulated miR-206 expression levels in the peripheral blood of patients with prolactinoma and in GH3 cells. Knockdown of miR-206 expression enhanced the proliferation and invasive ability of GH3 cells, while curcumin treatment effectively inhibited the aberrant biological behavior of GH3 cells enhanced by miR-206 knockdown. miR-206 knockdown also activated the Akt/mTOR signaling pathway and inhibited autophagy in GH3 cells, and these changes were effectively reversed by curcumin treatment. Thus, curcumin inhibited the Akt/mTOR signaling pathway and promoted cell autophagy by miR-206 upregulation, resulting in antitumor effects that inhibited prolactinoma cell proliferation and invasion.

Unlocking the Medicinal Potential of Plant-Derived Extracellular Vesicles: current Progress and Future Perspectives

Botanical preparations for herbal medicine have received more and more attention from drug researchers, and the extraction of active ingredients and their successful clinical application have become an important direction of drug research in major pharmaceutical companies, but the complexity of extracts, multiple side effects, and significant individual differences have brought many difficulties to the clinical application of herbal preparations. It is noteworthy that extracellular vesicles as active biomolecules extracted from medicinal plants are believed to be useful for the treatment of a variety of diseases, including cancer, inflammation, regenerative-restorative and degenerative diseases, which may provide a new direction for the clinical utilization of herbal preparations. In this review, we sort out recent advances in medicinal plant extracellular vesicles and discuss their potential as disease therapeutics. Finally, future challenges and research directions for the clinical translation of medicinal plant extracellular vesicles are also discussed, and we expect that continued development based on medicinal plant extracellular vesicles will facilitate the clinical application of herbal preparations.

Advances in traditional herbal formulation based nano-vaccine for cancer immunotherapy: Unraveling the enigma of complex tumor environment and multidrug resistance

Cancer is attributed to uncontrolled cell growth and is among the leading causes of death with no known effective treatment while complex tumor microenvironment (TME) and multidrug resistance (MDR) are major challenges for developing an effective therapeutic strategy. Advancement in cancer immunotherapy has been limited by the over-activation of the host immune response that ultimately affects healthy tissues or organs and leads to a feeble response of the patient's immune system against tumor cells. Besides, traditional herbal medicines (THM) have been well-known for their essential role in the treatment of cancer and are considered relatively safe due to their compatibility with the human body. Yet, poor solubility, low bio-availability, and lack of understanding about their pathophysiological mechanism halt their clinical application. Moreover, considering the complex TME and drug resistance, the most precarious and least discussed concerns for developing THM-based nano-vaccination, are identification of specific biomarkers for drug inhibitory protein and targeted delivery of bioactive ingredients of THM on the specific sites in tumor cells. The concept of THM-based nano-vaccination indicates immunomodulation of TME by THM-based bioactive adjuvants, exerting immunomodulatory effects, via targeted inhibition of key proteins involved in the metastasis of cancer. However, this concept is at its nascent stage and very few preclinical studies provided the evidence to support clinical translation. Therefore, we attempted to capsulize previously reported studies highlighting the role of THM-based nano-medicine in reducing the risk of MDR and combating complex tumor environments to provide a reference for future study design by discussing the challenges and opportunities for developing an effective and safe therapeutic strategy against cancer.

Herbal Medicines for the Improvement of Immune Function in Patients With Non-Small Cell Lung Cancer: A Systematic Review and Meta-Analysis

Background: Lung cancer has the highest mortality rate of all cancers worldwide. Conserving the immune system and reducing the adverse events associated with cancer treatment have become increasingly important. Our study aimed to investigate the immunological effects of herbal medicine (HM) alone, independent of conventional cancer therapies, in patients with non-small cell lung cancer (NSCLC). Methods: We searched 8 databases for articles published until March 2023. Bias risk was assessed using RevMan 5.4. Meta-analyses of CD4+ and CD8+ levels reported in the included RCTs were also performed. Results: A total of 610 patients from 5 RCTs were included in the analysis. Immune markers in the peripheral blood of patients treated with HM alone were compared with those in the control group. As a result of meta-analyses, CD4+ (three studies; mean difference(MD) = 5.21, 95 confidence interval (CI) [3.26, 7.27], I2 = 61%, n = 428) and CD4+/CD8+ (two studies; MD = 0.22, 95% CI [0.18, 0.26], I2 = 0%, n = 278) significantly increased in the treatment group, while CD8+ levels (three studies; MD = -3.04, 95% CI [-5.80, -0.29], I2 = 74%, n = 428) decreased in HM groups compared to comparison groups. In a single trial, IL-1, IL-6, tumor necrosis factor (TNF)-a levels and the number of Tregs in the treatment group significantly decreased, while Th17 levels and the Th17/Treg ratios increased. Conclusion: This study provides a comprehensive and systematic review of the immunological effects of HM in patients with NSCLC. Future studies should explore how the immunological effects of HM correlate with clinical outcomes, such as tumor response and survival rates.PROSPERO registration: CRD42023459.

Harnessing the power of traditional Chinese medicine monomers and compound prescriptions to boost cancer immunotherapy

At present, cancer is the largest culprit that endangers human health. The current treatment options for cancer mainly include surgical resection, adjuvant radiotherapy and chemotherapy, but their therapeutic effects and long-term prognosis are unsatisfactory. Immunotherapy is an emerging therapy that has completely transformed the therapeutic landscape of advanced cancers, and has tried to occupy a place in the neoadjuvant therapy of resectable tumors. However, not all patients respond to immunotherapy due to the immunological and molecular features of the tumors. Traditional Chinese Medicine (TCM) provides a new perspective for cancer treatment and is considered to have the potential as promising anti-tumor drugs considering its immunoregulatory properties. This review concludes commonly used TCM monomers and compounds from the perspective of immune regulatory pathways, aiming to clearly introduce the basic mechanisms of TCM in boosting cancer immunotherapy and mechanisms of several common TCM. In addition, we also summarized closed and ongoing trials and presented prospects for future development. Due to the significant role of immunotherapy in the treatment of non-small cell lung cancer (NSCLC), TCM combined with immunotherapy should be emphasized in NSCLC.

Identification of Bulbocodin D and C as novel STAT3 inhibitors and their anticancer activities in lung cancer cells

Cancer stands as one of the predominant causes of mortality globally, necessitating ongoing efforts to develop innovative therapeutics. Historically, natural products have been foundational in the quest for anticancer agents. Bulbocodin D (BD) and Bulbocodin C (BC), two bibenzyls derived from Pleione bulbocodioides (Franch.) Rolfe, have demonstrated notable in vitro anticancer activity. In human lung cancer A549 cells, the IC50s for BD and BC were 11.63 and 11.71 μmol·L-1, respectively. BD triggered apoptosis, as evidenced by an upsurge in Annexin V-positive cells and elevated protein expression of cleaved-PARP in cancer cells. Furthermore, BD and BC markedly inhibited the migratory and invasive potentials of A549 cells. The altered genes identified through RNA-sequencing analysis were integrated into the CMap dataset, suggesting BD's role as a potential signal transducer and activator of transcription 3 (STAT3) inhibitor. SwissDock and MOE analyses further revealed that both BD and BC exhibited a commendable binding affinity with STAT3. Additionally, a surface plasmon resonance assay confirmed the direct binding affinity between these compounds and STAT3. Notably, treatment with either BD or BC led to a significant reduction in p-STAT3 (Tyr 705) protein levels, regardless of interleukin-6 stimulation in A549 cells. In addition, the extracellular signal-regulated kinase (ERK) was activated after BD or BC treatment. An enhancement in cancer cell mortality was observed upon combined treatment of BD and U0126, the MEK1/2 inhibitor. In conclusion, BD and BC emerge as promising novel STAT3 inhibitors with potential implications in cancer therapy.

Drug Repurposing to Circumvent Immune Checkpoint Inhibitor Resistance in Cancer Immunotherapy

Immune checkpoint inhibitors (ICI) have achieved unprecedented clinical success in cancer treatment. However, drug resistance to ICI therapy is a major hurdle that prevents cancer patients from responding to the treatment or having durable disease control. Drug repurposing refers to the application of clinically approved drugs, with characterized pharmacological properties and known adverse effect profiles, to new indications. It has also emerged as a promising strategy to overcome drug resistance. In this review, we summarized the latest research about drug repurposing to overcome ICI resistance. Repurposed drugs work by either exerting immunostimulatory activities or abolishing the immunosuppressive tumor microenvironment (TME). Compared to the de novo drug design strategy, they provide novel and affordable treatment options to enhance cancer immunotherapy that can be readily evaluated in the clinic. Biomarkers are exploited to identify the right patient population to benefit from the repurposed drugs and drug combinations. Phenotypic screening of chemical libraries has been conducted to search for T-cell-modifying drugs. Genomics and integrated bioinformatics analysis, artificial intelligence, machine and deep learning approaches are employed to identify novel modulators of the immunosuppressive TME.