NLRP3 agonist enhances radiation-induced immune priming and promotes abscopal responses in anti-PD1 resistant model

DNA-PKcs Dysfunction Enhances the Antitumor Activity of Radioimmunotherapy by Activating the cGAS-STING Pathway in HNSCC

Introduction

Combining radiotherapy (RT) with immunotherapy for head and neck squamous cell carcinoma (HNSCC) has limited effectiveness due to the DNA damage repair (DDR) pathway activated by ionizing radiation. DNA-PK, encoded by the PRKDC gene, plays a key role in this repair. The potential improvement of radioimmunotherapy by inhibiting the DDR pathway is still unclear.

Methods

The effectiveness of different treatments on tumor growth and survival was tested using the C3H/HeN mouse tumor model. Flow cytometry analyzed treatment-induced immunophenotypic changes. In vitro, Western blot and PCR confirmed the impact of combining immunotherapy with RT on the cGAS-STING pathway after DNA-PKcs dysfunction.

Results

The combination of a DNA-PK inhibitor (NU7441), radiation therapy, and a PD-1 checkpoint inhibitor showed improved antitumor effects and extended survival in mice. Adding NU7441 into the RT and immunotherapy regimen increased CD8+ T cell infiltration. PRKDC alterations or DNA-PKcs dysfunction increased IR-induced DNA breaks, activating the cGAS-STING pathway and boosting the anti-tumor immune response.

Conclusion

These findings suggest that targeting the DDR pathway may represent a promising therapeutic strategy and biomarker to improve the efficacy of radioimmunotherapy in HNSCC.

The critical role of NLRP3 in drug resistance of cancers: Focus on the molecular mechanisms and possible therapeutics

Nod-like receptor protein 3 (NLRP3) is a member of the leucine-rich repeat-containing protein (NLR) canonical inflammasome family. It regulates the pathophysiology of cancer by facilitating immune responses and apoptotic proteins. Furthermore, it has been observed that chemotherapy activates NLRP3 in human malignancies. The secretion of IL-1β and IL-22 to promote cancer spread may be triggered by NLRP3 activation. Furthermore, earlier studies have exhibited that NLRP3 may cause medication resistance when used in cancer treatments given that cell viability may be regulated by NLRP3 depletion. Additionally, clinical studies have demonstrated correlation between NLRP3 expression, lymphogenesis, and cancer metastasis. Various NLRP3 agonists may cause the EMT process, stimulate IL-1β and Wnt/β-catenin signaling, and alter miRNA function in drug-resistant cells. This review seeks to clarify the possibility involvement of NLRP3-related pathways in the control of cancer cells' resistance to widely used treatment approaches, such as chemotherapy. In the end, an improved perception of the corresponding mechanisms behind NLRP3's tumor-supporting activities will help NLRP3-based treatments advance in the future.

Phase I study of BMS-986299, an NLRP3 agonist, as monotherapy and in combination with nivolumab and ipilimumab in patients with advanced solid tumors

PURPOSE

BMS-986299 is a first-in-class, NOD-, LRR-, and pyrin-domain containing-3 (NLRP3) inflammasome agonist enhancing adaptive immune and T-cell memory responses.

MATERIALS AND METHODS

This was a phase-I (NCT03444753) study that assessed the safety and tolerability of intra-tumoral BMS-986299 monotherapy (part 1A) and in combination (part 1B) with nivolumab, and ipilimumab in advanced solid tumors. Reported here are single-center results.

RESULTS

36 patients were enrolled, with breast (31%), colorectal (17%), and head and neck (14%) being the more commonly enrolled cancers. Most patients (58%) had received prior immunotherapy. Therapy was well-tolerated, with G1-G2 fever (70%), neutrophilia (36%), and leukocytosis (33%) being the most common treatment-related adverse events with one case of G4 interstitial nephritis and one case of G3 hepatotoxicity and G3 colitis. Intratumoral BMS-986299 monotherapy resulted in dose-dependent increases in systemic exposure with increase in tumor CTLs (67%), CD4+ TILs (63%), along with notable above twofold increases in serum IL-1B, G-CSF and IL-6 at doses above 2000 µg. Systemic BMS-986299 exposure was positively associated with systemic cytokine elevation for G-CSF and IL-6. No antitumor activity was noted in BMS-986299 monotherapy cohort. However, in the combination therapy cohort (BMS-986299+nivolumab+ipilimumab), overall objective response rate was 10%, with confirmed PRs observed in TNBC, hormone receptor-positive, human epidermal growth factor receptor 2 negative breast cancer, and cutaneous squamous cell carcinoma.

CONCLUSION

BMS-986299 in combination with immune checkpoint inhibitors demonstrated manageable toxicities, good tolerability, and promising antitumor activity in certain cancer types.

TRIAL REGISTRATION NUMBER

NCT03444753.

Interaction Between Autophagy and the Inflammasome in Human Tumors: Implications for the Treatment of Human Cancers

Autophagy is a physiologically regulated cellular process orchestrated by autophagy-related genes (ATGs) that, depending on the tumor type and stage, can either promote or suppress tumor growth and progression. It can also modulate cancer stem cell maintenance and immune responses. Therefore, targeted manipulation of autophagy may inhibit tumor development by overcoming tumor-promoting mechanisms. The inflammasome is another multifunctional bioprocess that induces a form of pro-inflammatory programmed cell death, called pyroptosis. Dysregulation or overactivation of the inflammasome has been implicated in tumor pathogenesis and development. Additionally, autophagy can inhibit the NLRP3 inflammasome by removing inflammatory drivers. Recent research suggests that the NLRP3 inflammasome, in turn, affects autophagy. Understanding the complex interplay between autophagy and inflammasomes could lead to more precise and effective strategies for cancer treatments. In this review, we summarize the impact of autophagy and inflammasome dysregulation on tumor progression or suppression. We then highlight their targeting for cancer treatment as monotherapy or in combination with other therapies. Furthermore, we discuss the interaction between autophagy and tumor-promoting inflammation or the NLRP3 inflammasome. Finally, based on recent findings, we review the potential of this interaction for cancer treatment.

Unraveling the NLRP family: Structure, function, activation, critical influence on tumor progression, and potential as targets for cancer therapy

The innate immune system serves as the body's initial defense, swiftly detecting danger via pattern recognition receptors (PRRs). Among these, nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing proteins (NLRPs) are pivotal in recognizing pathogen-associated and damage-associated molecular patterns, thereby triggering immune responses. NLRPs, the most extensively studied subset within the NLR family, form inflammasomes that regulate inflammation, essential for innate immunity activation. Recent research highlights NLRPs' significant impact on various human diseases, including cancer. With differential expression across organs, NLRPs influence cancer progression by modulating immune reactions, cell fate, and proliferation. Their clinical significance in cancer makes them promising therapeutic targets. This review provides a comprehensive overview of the structure, function, activation mechanism of the NLRPs family and its potential role in cancer progression. In addition, we particularly focused on the concept of NLRP as a therapeutic target and its potential value in combination with immune checkpoint inhibitors.

Igniting hope: Harnessing NLRP3 inflammasome-GSDMD-mediated pyroptosis for cancer immunotherapy

In the contemporary landscape of oncology, immunotherapy, represented by immune checkpoint blockade (ICB) therapy, stands out as a beacon of innovation in cancer treatment. Despite its promise, the therapy's progression is hindered by suboptimal clinical response rates. Addressing this challenge, the modulation of the NLRP3 inflammasome-GSDMD-mediated pyroptosis pathway holds promise as a means to augment the efficacy of immunotherapy. In the pathway, the NLRP3 inflammasome serves as a pivotal molecular sensor that responds to inflammatory stimuli within the organism. Its activation leads to the release of cytokines interleukin 1β and interleukin 18 through the cleavage of GSDMD, thereby forming membrane pores and potentially resulting in pyroptosis. This cascade of processes exerts a profound impact on tumor development and progression, with its function and expression exhibiting variability across different tumor types and developmental stages. Consequently, understanding the specific roles of the NLRP3 inflammasome and GSDMD-mediated pyroptosis in diverse tumors is imperative for comprehending tumorigenesis and crafting precise therapeutic strategies. This review aims to elucidate the structure and activation mechanisms of the NLRP3 inflammasome, as well as the induction mechanisms of GSDMD-mediated pyroptosis. Additionally, we provide a comprehensive overview of the involvement of this pathway in various cancer types and its applications in tumor immunotherapy, nanotherapy, and other fields. Emphasis is placed on the feasibility of leveraging this approach to enhance ICB therapy within the field of immunotherapy. Furthermore, we discuss the potential applications of this pathway in other immunotherapy methods, such as chimeric antigen receptor T-cell (CAR-T) therapy and tumor vaccines.

Small molecule innate immune modulators in cancer therapy

Immunotherapy has proved to be a breakthrough in cancer treatment. So far, a bulk of the approved/late-stage cancer immunotherapy are antibody-based. Although these antibody-based drugs have demonstrated great promise, a majority of them are limited due to their access to extracellular targets, lack of oral bioavailability, tumor microenvironment penetration, induction of antibody dependent cytotoxicity etc. In recent times, there has been an increased research focus on the development of small molecule immunomodulators since they have the potential to overcome the aforementioned limitations posed by antibodies. Furthermore, while most biologics based therapeutics that are in clinical use are limited to modulating the adaptive immune system, very few clinically approved therapeutic modalities exist that modulate the innate immune system. The innate immune system, which is the body's first line of defense, has the ability to turn cold tumors hot and synergize strongly with existing adaptive immune modulators. In preclinical studies, small molecule innate immune modulators have demonstrated synergistic efficacy as combination modalities with current standard-of-care immune checkpoint antibodies. In this review, we highlight the recent advances made by small molecule innate immunomodulators in cancer immunotherapy.

Inhibition of MER proto-oncogene tyrosine kinase by an antisense oligonucleotide enhances treatment efficacy of immunoradiotherapy

BACKGROUND

The combination of radiotherapy and immunotherapy (immunoradiotherapy) has been increasingly used for treating a wide range of cancers. However, some tumors are resistant to immunoradiotherapy. We have previously shown that MER proto-oncogene tyrosine kinase (MerTK) expressed on macrophages mediates resistance to immunoradiotherapy. We therefore sought to develop therapeutics that can mitigate the negative impact of MerTK. We designed and developed a MerTK specific antisense oligonucleotide (ASO) and characterized its effects on eliciting an anti-tumor immune response in mice.

METHODS

344SQR cells were injected into the right legs on day 0 and the left legs on day 4 of 8-12 weeks old female 129sv/ev mice to establish primary and secondary tumors, respectively. Radiation at a dose of 12 Gy was given to the primary tumors on days 8, 9, and 10. Mice received either anti-PD-1, anti-CTLA-4 or/and MerTK ASO starting from day 1 post tumor implantation. The composition of the tumor microenvironment and the level of MerTK on macrophages in the tumor were evaluted by flow cytometry. The expression of immune-related genes was investigated with NanoString. Lastly, the impact of MerTK ASO on the structure of the eye was histologically evaluated.

RESULTS

Remarkably, the addition of MerTK ASO to XRT+anti-PD1 and XRT+anti-CTLA4 profoundly slowed the growth of both primary and secondary tumors and significantly extended survival. The ASO significantly reduced the expression of MerTK in tumor-associated macrophages (TAMs), reprograming their phenotype from M2 to M1. In addition, MerTK ASO increased the percentage of Granzyme B+ CD8+ T cells in the secondary tumors when combined with XRT+anti-CTLA4. NanoString results demonstrated that the MerTK ASO favorably modulated immune-related genes for promoting antitumor immune response in secondary tumors. Importantly, histological analysis of eye tissues demonstrated that unlike small molecules, the MerTK ASO did not produce any detectable pathology in the eyes.

CONCLUSIONS

The MerTK ASO can significantly downregulate the expression of MerTK on TAMs, thereby promoting antitumor immune response. The combination of MerTK ASO with immunoradiotherapy can safely and significantly slow tumor growth and improve survival.

Pyroptotic cell death: an emerging therapeutic opportunity for radiotherapy

Pyroptotic cell death, an inflammatory form of programmed cell death (PCD), is emerging as a potential therapeutic opportunity for radiotherapy (RT). RT is commonly used for cancer treatment, but its effectiveness can be limited by tumor resistance and adverse effects on healthy tissues. Pyroptosis, characterized by cell swelling, membrane rupture, and release of pro-inflammatory cytokines, has been shown to enhance the immune response against cancer cells. By inducing pyroptotic cell death in tumor cells, RT has the potential to enhance treatment outcomes by stimulating anti-tumor immune responses and improving the overall efficacy of RT. Furthermore, the release of danger signals from pyroptotic cells can promote the recruitment and activation of immune cells, leading to a systemic immune response that may target distant metastases. Although further research is needed to fully understand the mechanisms and optimize the use of pyroptotic cell death in RT, it holds promise as a novel therapeutic strategy for improving cancer treatment outcomes. This review aims to synthesize recent research on the regulatory mechanisms underlying radiation-induced pyroptosis and to elucidate the potential significance of this process in RT. The insights gained from this analysis may inform strategies to enhance the efficacy of RT for tumors.

NLRP3 and cancer: Pathogenesis and therapeutic opportunities

More than a decade ago IL-1 blockade was suggested as an add-on therapy for the treatment of cancer. This proposal was based on the overall safety record of anti-IL-1 biologics and the anti-tumor properties of IL-1 blockade in animal models of cancer. Today, a new frontier in IL-1 activity regulation has developed with several orally active NLRP3 inhibitors currently in clinical trials, including cancer. Despite an increasing body of evidence suggesting a role of NLRP3 and IL-1-mediated inflammation driving cancer initiation, immunosuppression, growth, and metastasis, NLRP3 activation in cancer remains controversial. In this review, we discuss the recent advances in the understanding of NLRP3 activation in cancer. Further, we discuss the current opportunities for NLRP3 inhibition in cancer intervention with novel small molecules.