Immunotherapeutic approach to reduce senescent cells and alleviate senescence-associated secretory phenotype in mice

Accumulation of senescent cells (SNCs) with a senescence-associated secretory phenotype (SASP) has been implicated as a major source of chronic sterile inflammation leading to many age-related pathologies. Herein, we provide evidence that a bifunctional immunotherapeutic, HCW9218, with capabilities of neutralizing TGF-β and stimulating immune cells, can be safely administered systemically to reduce SNCs and alleviate SASP in mice. In the diabetic db/db mouse model, subcutaneous administration of HCW9218 reduced senescent islet β cells and SASP resulting in improved glucose tolerance, insulin resistance, and aging index. In naturally aged mice, subcutaneous administration of HCW9218 durably reduced the level of SNCs and SASP, leading to lower expression of pro-inflammatory genes in peripheral organs. HCW9218 treatment also reverted the pattern of key regulatory circadian gene expression in aged mice to levels observed in young mice and impacted genes associated with metabolism and fibrosis in the liver. Single-nucleus RNA Sequencing analysis further revealed that HCW9218 treatment differentially changed the transcriptomic landscape of hepatocyte subtypes involving metabolic, signaling, cell-cycle, and senescence-associated pathways in naturally aged mice. Long-term survival studies also showed that HCW9218 treatment improved physical performance without compromising the health span of naturally aged mice. Thus, HCW9218 represents a novel immunotherapeutic approach and a clinically promising new class of senotherapeutic agents targeting cellular senescence-associated diseases.

A novel interleukin-2-based fusion molecule, HCW9302, differentially promotes regulatory T cell expansion to treat atherosclerosis in mice

Atherosclerosis is a chronic inflammatory disease caused by deposition of oxidative low-density lipoprotein (LDL) in the arterial intima which triggers the innate immune response through myeloid cells such as macrophages. Regulatory T cells (Tregs) play an important role in controlling the progression or regression of atherosclerosis by resolving macrophage-mediated inflammatory functions. Interleukin-2 (IL-2) signaling is essential for homeostasis of Tregs. Since recombinant IL-2 has an unfavorable pharmacokinetic profile limiting its therapeutic use, we constructed a fusion protein, designated HCW9302, containing two IL-2 domains linked by an extracellular tissue factor domain. We found that HCW9302 exhibited a longer serum half-life with an approximately 1000-fold higher affinity for the IL-2Rα than IL-2. HCW9302 could be administered to mice at a dosing range that expanded and activated Tregs but not CD4⁺ effector T cells. In an ApoE^-/- mouse model, HCW9302 treatment curtailed the progression of atherosclerosis through Treg activation and expansion, M2 macrophage polarization and myeloid-derived suppressor cell induction. HCW9302 treatment also lessened inflammatory responses in the aorta. Thus, HCW9302 is a potential therapeutic agent to expand and activate Tregs for treatment of inflammatory and autoimmune diseases.

GpsB Coordinates Cell Division and Cell Surface Decoration by Wall Teichoic Acids in Staphylococcus aureus

Bacterial cell division is a complex and highly regulated process requiring the coordination of many different proteins. Despite substantial work in model organisms, our understanding of the systems regulating cell division in noncanonical organisms, including critical human pathogens, is far from complete. One such organism is Staphylococcus aureus, a spherical bacterium that lacks known cell division regulatory proteins. Recent studies on GpsB, a protein conserved within the Firmicutes phylum, have provided insight into cell division regulation in S. aureus and other related organisms. It has been revealed that GpsB coordinates cell division and cell wall synthesis in multiple species. In S. aureus, we have previously shown that GpsB directly regulates FtsZ polymerization. In this study, using Bacillus subtilis as a tool, we isolated spontaneous suppressors that abrogate the lethality of S. aureus GpsB overproduction in B. subtilis. Through characterization, we identified several residues important for the function of GpsB. Furthermore, we discovered an additional role for GpsB in wall teichoic acid (WTA) biosynthesis in S. aureus. Specifically, we show that GpsB directly interacts with the WTA export protein TarG. We also identified a region in GpsB that is crucial for this interaction. Analysis of TarG localization in S. aureus suggests that WTA machinery is part of the divisome complex. Taken together, this research illustrates how GpsB performs an essential function in S. aureus by directly linking the tightly regulated cell cycle processes of cell division and WTA-mediated cell surface decoration. IMPORTANCE Cytokinesis in bacteria involves an intricate orchestration of several key cell division proteins and other factors involved in building a robust cell envelope. Presence of teichoic acids is a signature characteristic of the Gram-positive cell wall. By characterizing the role of Staphylococcus aureus GpsB, an essential cell division protein in this organism, we have uncovered an additional role for GpsB in wall teichoic acid (WTA) biosynthesis. We show that GpsB directly interacts with TarG of the WTA export complex. We also show that this function of GpsB may be conserved in other GpsB homologs as GpsB and the WTA exporter complex follow similar localization patterns. It has been suggested that WTA acts as a molecular signal to control the activity of autolytic enzymes, especially during the separation of conjoined daughter cells. Thus, our results reveal that GpsB, in addition to playing a role in cell division, may also help coordinate WTA biogenesis.

Abstract 1299: Immunotherapeutic hcw9218 enhances anti-tumor activity of chemotherapy by facilitating immune-mediated elimination of therapy induced senescent cells

Advances in immunostimulatory and anti-immunosuppressive therapeutics have revolutionized cancer treatment. Here, we report a novel heterodimeric bifunctional fusion molecule, HCW9218, constructed using our soluble tissue factor (TF)-based scaffold technology comprising extracellular domains of the human transforming growth factor-β (TGF-β) receptor II and a human interleukin (IL)-15/IL-15 receptor α complex. This fusion complex exhibited TGF-β neutralizing activity in vitro and sequestered plasma TGF-β in vivo. Subcutaneous administration of HCW9218 was well tolerated in mice, with a half-life sufficient to provide long lasting biological activity. HCW9218 enhanced metabolic and cytotoxic activities of immune cells (CD8+ T cells, NK cells) and reduced tumor progression in models of chemotherapy induced senescence (TIS, docetaxel for B16F10 tumors and gemcitabine plus nab-paclitaxel for SW1990 tumor models) and non-TIS in vivo. Mechanistically, HCW9218 treatment not only affected the immunosuppressive tumor microenvironment but also enhanced CD8+ T cells and NK cells infiltration and cytotoxicity in the tumors to eliminate TIS cancer cells. Immune-depletion studies showed that HCW9218-activated NK cells played a pivotal role in TIS cancer cell removal. HCW9218 treatment following docetaxel chemotherapy further enhanced efficacy of tumor antigen-specific and anti-PDL-1 antibodies in B16F10 tumor-bearing mice. We also show that HCW9218 treatment lowered senescence associated secretory phenotype (SASP) factors in off-target tissues in chemotherapy treated tumor-bearing mice. Thus, HCW9218 may serve as a novel therapeutic (monotherapy or in combination with chemotherapy) to simultaneously provide immunostimulation and lessen immunosuppression associated with tumors. HCW9218 has been cleared by the U.S. Food and Drug Administration to proceed for evaluation in a first-inhuman Phase 1b clinical trial in patients with advanced pancreatic cancer.

Citation Format: Pallavi Chaturvedi, Varghese George, Bai Liu, Niraj Shrestha, Meng Wang, Micheal Dee, Xiaoyun Zhu, Jack Egan, Jin-an Jiao, Catherine Spanoudis, Jilan Xing, Victor Gallo, Christian Echeverri, Lijing You, Lin Kong, Gabriela Muniz, Peter Rhode, Hing Wong. Immunotherapeutic hcw9218 enhances anti-tumor activity of chemotherapy by facilitating immune-mediated elimination of therapy induced senescent cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1299.

Immunotherapeutic HCW9218 augments anti-tumor activity of chemotherapy via NK cell-mediated reduction of therapy-induced senescent cells

Therapy induced senescence (TIS) in tumors and TIS cancer cells secrete proinflammatory senescence-associated secretory phenotype (SASP) factors. SASP factors promote TIS cancer cells to re-enter the growth cycle with stemness characteristics, resulting in chemo-resistance and disease relapse. Herein, we show that the immunotherapeutic HCW9218, comprising transforming growth factor-β (TGF-β) receptor II and interleukin (IL)-15/IL-15 receptor α domains, enhances metabolic and cytotoxic activities of immune cells and reduces TIS tumor cells in vivo to improve the efficacy of docetaxel and gemcitabine plus nab-paclitaxel against B16F10 melanoma and SW1990 pancreatic tumors, respectively. Mechanistically, HCW9218 treatment reduces the immunosuppressive tumor microenvironment and enhances immune cell infiltration and cytotoxicity in the tumors to eliminate TIS cancer cells. Immuno-depletion analysis suggests that HCW9218-activated natural killer cells play a pivotal role in TIS cancer cell removal. HCW9218 treatment following docetaxel chemotherapy further enhances efficacy of tumor antigen-specific and anti-programmed death-ligand 1 (PD-L1) antibodies in B16F10 tumor-bearing mice. We also show that HCW9218 treatment decreases TIS cells and lowers SASP factors in off-target tissues caused by chemotherapy of tumor-bearing mice. Collectively, HCW9218 has the potential to significantly enhance anti-tumor efficacy of chemotherapy, therapeutic antibodies, and checkpoint blockade by eliminating TIS cancer cells while reducing TIS-mediated proinflammatory side effects in normal tissues.

Bifunctional TGF-β trap/IL-15 Protein Complex Elicits Potent NK Cell and CD8+ T Cell Immunity Against Solid Tumors

Advances in immunostimulatory and anti-immunosuppressive therapeutics have revolutionized cancer treatment. However, novel immunotherapeutics with these dual functions are not frequently reported. Here we describe the creation of a heterodimeric bifunctional fusion molecule, HCW9218, constructed using our soluble tissue factor-based scaffold technology. This complex comprises extracellular domains of the human transforming growth factor-β (TGF-β) receptor II and a human interleukin (IL)-15/IL-15 receptor α complex. HCW9218 can be readily expressed in CHO cells and purified using antibody-based affinity chromatography in a large-scale manufacturing setting. HCW9218 potently activates mouse natural killer (NK) cells and CD8⁺ T cells in vitro and in vivo to enhance cell proliferation, metabolism and antitumor cytotoxic activities. Similarly, human immune cells become activated with increased cytotoxicity following incubation with HCW9218. This fusion complex also exhibits TGF-β neutralizing activity in vitro and sequesters plasma TGF-β in vivo. In a syngeneic B16F10 melanoma model, HCW9218 displayed strong antitumor activity mediated by NK cells and CD8⁺ T cells, and increased their infiltration into tumors. Repeat-dose subcutaneous administration of HCW9218 was well tolerated by mice, with a half-life sufficient to provide long lasting biological activity. Thus, HCW9218 may serve as a novel therapeutic to simultaneously provide immunostimulation and lessen immunosuppression associated with tumors.

A Novel Bifunctional Fusion Protein Comprising of TGF-βRII trap and IL15/IL-15Rα as an Immunotherapeutic against Cancer

Interleukin-15 (IL-15) is a promising cytokine for cancer therapy. However, it has shown limited antitumor efficacy as monotherapy in clinical trials to date. Removal of immunosuppression of the tumor microenvironment is considered a promising approach to enhance IL-15-mediated immune responses. TGF-β is a key component for creating an immunosuppressive tumor microenvironment. Therefore, we constructed a novel bifunctional fusion protein complex, designated HCW9218, comprising a soluble fusion of two TGFβRII, human tissue factor, and human IL-15, and a second soluble fusion of two TGFβRII and a sushi domain of IL-15Rα. HCW9218 activates IL-15R signaling and the dimeric TGFβRII functions as “trap” for all the three TGF-β isoforms. In healthy and tumor-bearing C57/BL6 mice, subcutaneously administrated HCW9218 was well tolerated with a long serum half-life and was able to stimulate and induce proliferation of CD8+ T cells and NK cells. Splenocytes from HCW9218-treated mice showed enhanced metabolic activity and cytotoxicity against Yac-1 target cells compared to untreated mouse splenocytes. In the syngeneic B16F10 melanoma mouse model, a single-dose of HCW9218 exhibited strong antitumor activity in combination with chemotherapy and TA99 antibody. HCW9218 also significantly increased immune cell infiltration into tumors. Mutagenesis studies demonstrated that both the TGFβRII and IL-15/IL-15Rα domains are essential for antitumor efficacy of HCW9218. Collectively, our preclinical data demonstrate that HCW9218 elicits potent immune responses with a remarkable safety profile and serves as a novel immunotherapeutic against cancer alone or in combination with therapeutic antibodies.

A Novel IL2-based Immunotherapeutic Protein Prevents the Development of Atherosclerosis in ApoE−/− mice and LDLR−/− mice

Atherosclerosis is the leading cause of coronary heart disease and stroke. Sterile Inflammation, resulting from activation of the inflammasome NLRP3, plays a key role in the pathophysiology of atherosclerosis. Studies suggested that low-dose rIL-2 may be effective in treating autoimmune and inflammatory diseases by inducing Treg cells. Since rIL-2 has unfavorable pharmacokinetic profile in humans, we constructed a fusion protein, designated HCW9302, containing two IL-2 domains linked by an extracellular tissue factor domain, to extend the half-live of IL-2 for Treg expansion. In vitro treatment of human PBMCs with HCW9302 significantly expanded CD4+/CD25+/FoxP3+ Treg cells without activating CD4+ and CD8+ T cells over a broader concentration range than rIL2. Subcutaneous injection of HCW9302 (3 mg/kg every 2 – 3 weeks) into atherosclerosis-prone mice (ApoE−/− mice and LDLR−/− mice fed the Western Diet (WD) for 6 weeks) significantly increased the percentage of Treg cells, NK cells and CD8+ T cells in blood compared to the PBS-treated control group (p<0.001). Cytokines associated with atherosclerosis, including IL-1β and MCP-1, were also significantly decreased in the HCW9302-treated group, suggesting HCW9302 can moderate inflammasome NLRP3 activities. Remarkably, HCW9302 lowered the fasting blood glucose and insulin resistance. In aortas evaluated by the en face method at week 13 of WD, the ratio of plaque size to aortic surface was also significantly lower in HCW9302-treated mice compared to controls. HCW9302 treatment was well tolerated in both models. In summary, HCW9302 can effectively prevent the development of atherosclerosis in ApoE−/− mice and LDLR−/− mice, potentially through expansion of Treg cells.

A novel, non-feeder-cell approach to generate large numbers of Cytokine-Induced Memory-Like NK cells for adoptive cells therapies

We have constructed two heterodimeric multi-cytokine fusions, HCW9201 and HCW9206, to support a “Kick and Expand” approach to activate and induce proliferation of purified NK cells for adoptive cell therapy (ACT). HCW9201 is a heterodimeric fusion protein complex comprising human IL-15 (complexed with an IL-15Rα-sushi domain), IL-18 and IL-12. HCW9206 is heterodimeric fusion protein comprising human IL-15 (complexed with an IL-15Rα-sushi domain), IL-7, and IL-21. When purified human NK cells from peripheral blood were activated with HCW9201 for three hours and then incubated with HCW9206 in combination with a capture antibody, the HCW9201-activated NK cells expanded approximately 100–300 folds within 14 days. The expanded NK cells exhibit a cytokine-induced memory-like (CIML) phenotype with a high metabolic rate and respiratory capacity, remarkable anti-tumor activity, and persistence when they were adoptively transferred into NSG mice. They also retained their heightened responsiveness when re-stimulated with tumor targets. Cytokine dependent epigenetic demethylation imprints of the Ifng promoter region were also observed for at least 10 days after the NK cells were adoptively transferred to NSG mice. In conclusion, a simple, scalable, non-feeder-cell-based “Kick and Expand” process was developed to support the generation of large numbers of CIML NK cells for multiple rounds of ACT using peripheral blood NK cell. We also provide data to show that these CIML NK cells are an excellent source for generation of CAR-NK cells.

An essential Staphylococcus aureus cell division protein directly regulates FtsZ dynamics

Binary fission has been well studied in rod-shaped bacteria, but the mechanisms underlying cell division in spherical bacteria are poorly understood. Rod-shaped bacteria harbor regulatory proteins that place and remodel the division machinery during cytokinesis. In the spherical human pathogen Staphylococcus aureus, we found that the essential protein GpsB localizes to mid-cell during cell division and co-constricts with the division machinery. Depletion of GpsB arrested cell division and led to cell lysis, whereas overproduction of GpsB inhibited cell division and led to the formation of enlarged cells. We report that S. aureus GpsB, unlike other Firmicutes GpsB orthologs, directly interacts with the core divisome component FtsZ. GpsB bundles and organizes FtsZ filaments and also stimulates the GTPase activity of FtsZ. We propose that GpsB orchestrates the initial stabilization of the Z-ring at the onset of cell division and participates in the subsequent remodeling of the divisome during cytokinesis.

A bacterium called Staphylococcus aureus causes many infections in humans, especially in hospital patients with weakened immune systems. These infections are generally treated with drugs known as antibiotics that interact with specific proteins in the bacteria to kill the cells, or stop them from growing. However, some S. aureus infections are resistant to the antibiotics currently available so there is a need to develop new drugs that target different bacterial proteins.

Bacteria multiply by dividing to make identical copies of themselves. When a bacterium is preparing to divide, filaments made of a protein called FtsZ form a ring at the site where the cell will split. Many other proteins are involved in controlling how and when a cell divides. For example, several species of bacteria harbor a dispensable cell division protein called GpsB. In at least one organism, it helps to maintain the proper shape of the cell during cell division. In S. aureus, though, GpsB is essential for cells to survive and could therefore be a potential target for new antibiotics. However, its role in S. aureus has not been studied.

Eswara et al. have now used genetic and biochemical approaches to study the S. aureus form of the GpsB protein. The experiments show that GpsB moves to the middle of S. aureus cells just before they begin to divide and binds directly to FtsZ. This helps to secure the position of FtsZ across the middle of the cell and activates the protein so that the cell can begin to divide into two. In cells that produce too much GpsB, the FtsZ proteins become active too early, leading to the cells growing larger and larger until they burst.

The findings of Eswara et al. reveal that GpsB plays a different role in S. aureus cells than in some other species of bacteria. Further studies into such differences could help researchers to develop new antibiotics, as well as improving our understanding of why bacteria are so diverse.