A next-generation tumor-targeting IL-2 preferentially promotes tumor-infiltrating CD8+ T-cell response and effective tumor control

Novel engineered IL-2 Nemvaleukin alfa combined with PD1 checkpoint blockade enhances the systemic anti-tumor responses of radiation therapy

BACKGROUND

Combining interleukin-2 (IL-2) with radiotherapy (RT) and immune checkpoint blockade (ICB) has emerged as a promising approach to address ICB resistance. However, conventional IL-2 cytokine therapy faces constraints owing to its brief half-life and adverse effects. RDB 1462, the mouse ortholog of Nemvaleukin alfa, is an engineered IL-2 with an intermediate affinity that selectively stimulates antitumor CD8 T and NK cells while limiting regulatory T cell expansion. This study aimed to evaluate the antitumor activity and mechanism of action of the combination of RDB 1462, RT, and anti-PD1 in mouse tumor models.

METHODS

Two bilateral lung adenocarcinoma murine models were established using 344SQ-Parental and 344SQ anti-PD1-resistant cell lines. Primary tumors were treated with RT, and secondary tumors were observed for evidence of abscopal effects. We performed immune phenotyping by flow cytometry, analyzed 770 immune-related genes using NanoString, and performed T cell receptor (TCR) repertoire analysis. Serum pro-inflammatory cytokine markers were analyzed by 23-plex kit.

RESULTS

Compared to native IL-2 (RDB 1475), RDB 1462 demonstrated superior systemic antitumoral responses, attributable, at least in part, to augmented levels of CD4 and CD8 T cells with the latter. Our findings reveal substantial reductions in primary and secondary tumor volumes compared to monotherapy controls, with some variability observed among different dosing schedules of RDB 1462 combined with RT. Blood and tumor tissue-based flow cytometric phenotyping reveals an increase in effector memory CD8 and CD4 T cells and a decrease in immunosuppressive cells accompanied by a significant increase in IL-2, IFN-γ, and GM-CSF levels in the combination group. Transcriptomic profiling and TCR sequencing reveal favorable gene expression and T cell repertoire patterns with the dual combination. Furthermore, integrating anti-PD1 therapy with RT and RDB 1462 further reduced primary and secondary tumor volumes, prolonged survival, and decreased lung metastasis. Observations of immune cell profiles indicated that RT with escalating doses of RDB 1462 significantly reduced tumor growth and increased tumor-specific immune cell populations.

CONCLUSION

The addition of Nemvaleukin therapy may enhance responses to RT alone and in combination with anti-PD1.

Tumor-Homing Antibody-Cytokine Fusions for Cancer Therapy

Recombinant cytokine products have emerged as a promising avenue in cancer therapy due to their capacity to modulate and enhance the immune response against tumors. However, their clinical application is significantly hindered by systemic toxicities already at low doses, thus preventing escalation to therapeutically active regimens. One promising approach to overcoming these limitations is using antibody-cytokine fusion proteins (also called immunocytokines). These biopharmaceuticals leverage the targeting specificity of antibodies to deliver cytokines directly to the tumor microenvironment, thereby reducing systemic exposure and enhancing the therapeutic index. This review comprehensively examines the development and potential of antibody-cytokine fusion proteins in cancer therapy. It explores the molecular characteristics that influence the performance of these fusion proteins, and it highlights key findings from preclinical and clinical studies, illustrating the potential of immunocytokines to improve treatment outcomes in cancer patients. Recent advancements in the field, such as novel engineering strategies and combination strategies to enhance the efficacy and safety of immunocytokines, are also discussed. These innovations offer new opportunities to optimize this class of biotherapeutics, making them a more viable and effective option for cancer treatment. As the field continues to evolve, understanding the critical factors that influence the performance of immunocytokines will be essential for successfully translating these therapies into clinical practice.

Strategies to enhance the therapeutic efficacy of anti-PD-1 antibody, anti-PD-L1 antibody and anti-CTLA-4 antibody in cancer therapy

Although immune checkpoint inhibitors (anti-PD-1 antibody, anti-PD-L1 antibody, and anti-CTLA-4 antibody) have displayed considerable success in the treatment of malignant tumors, the therapeutic effect is still unsatisfactory for a portion of patients. Therefore, it is imperative to develop strategies to enhance the effect of these ICIs. Increasing evidence strongly suggests that the key to this issue is to transform the tumor immune microenvironment from a state of no or low immune infiltration to a state of high immune infiltration and enhance the tumor cell-killing effect of T cells. Therefore, some combination strategies have been proposed and this review appraise a summary of 39 strategies aiming at enhancing the effectiveness of ICIs, which comprise combining 10 clinical approaches and 29 foundational research strategies. Moreover, this review improves the comprehensive understanding of combination therapy with ICIs and inspires novel ideas for tumor immunotherapy.

Stimulating the Antitumor Immune Response Using Immunocytokines: A Preclinical and Clinical Overview

Cytokines are immune modulators which can enhance the immune response and have been proven to be an effective class of immunotherapy. Nevertheless, the clinical use of cytokines in cancer treatment has faced several challenges associated with poor pharmacokinetic properties and the occurrence of adverse effects. Immunocytokines (ICKs) have emerged as a promising approach to overcome the pharmacological limitations observed with cytokines. ICKs are fusion proteins designed to deliver cytokines in the tumor microenvironment by taking advantage of the stability and specificity of immunoglobulin-based scaffolds. Several technological approaches have been developed. This review focuses on ICKs designed with the most impactful cytokines in the cancer field: IL-2, TNFα, IL-10, IL-12, IL-15, IL-21, IFNγ, GM-CSF, and IFNα. An overview of the pharmacological effects of the naked cytokines and ICKs tested for cancer therapy is detailed. A particular emphasis is given on the immunomodulatory effects of ICKs associated with their technological design. In conclusion, this review highlights active ways of development of ICKs. Their already promising results observed in clinical trials are likely to be improved with the advances in targeting technologies such as cytokine/linker engineering and the design of multispecific antibodies with tumor targeting and immunostimulatory functional properties.

IL-2 based cancer immunotherapies: an evolving paradigm

Discovered over 4 decades ago in the supernatants of activated T cells, interleukin-2 (IL-2) is a potent pleiotropic cytokine involved in the regulation of immune responses. It is required for effector T cell expansion and differentiation as well as for peripheral tolerance induced by regulatory T cells. High-dose IL-2 treatment was the first FDA-approved immunotherapy for renal cell carcinoma and melanoma, achieving single agent complete and durable responses, albeit only in a small proportion of patients. The therapeutic potential of wild type IL-2 is clinically limited by its short half-life and severe vascular toxicity. Moreover, the activation of regulatory T cells and the terminal differentiation of effector T cells on IL-2 pose additional restrictions. To overcome the toxicity of IL-2 in order to realize its full potential for patients, several novel engineering strategies are being developed and IL-2 based immunotherapy for cancer has emerged as a burgeoning field of clinical and experimental research. In addition, combination of IL-2 with PD-1/L1 pathway blockade shows vastly improved anti-tumor efficacy over either monotherapy in preclinical tumor models. In this review we discuss the biological characteristics of IL-2 and its receptors, as well as its efficacy and treatment limiting toxicities in cancer patients. We also explore the efforts aimed at developing novel and safer IL-2 therapies to harness the full therapeutic potential of this cytokine.

The role of CD8 PET imaging in guiding cancer immunotherapy

Currently, immunotherapy is being widely used for treating cancers. However, the significant heterogeneity in patient responses is a major challenge for its successful application. CD8-positive T cells (CD8+ T cells) play a critical role in immunotherapy. Both their infiltration and functional status in tumors contribute to treatment outcomes. Therefore, accurate monitoring of CD8+ T cells, a potential biomarker, may improve therapeutic strategy. Positron emission tomography (PET) is an optimal option which can provide molecular imaging with enhanced specificity. This review summarizes the mechanism of action of CD8+ T cells in immunotherapy, and highlights the recent advancements in PET-based tracers that can visualize CD8+ T cells and discusses their clinical applications to elucidate their potential role in cancer immunotherapy.

CD8-Targeted IL2 Unleashes Tumor-Specific Immunity in Human Cancer Tissue by Reviving the Dysfunctional T-cell Pool

Tumor-specific CD8+ T cells are key effectors of antitumor immunity but are often rendered dysfunctional in the tumor microenvironment. Immune-checkpoint blockade can restore antitumor T-cell function in some patients; however, most do not respond to this therapy, often despite T-cell infiltration in their tumors. We here explored a CD8-targeted IL2 fusion molecule (CD8-IL2) to selectively reactivate intratumoral CD8+ T cells in patient-derived tumor fragments. Treatment with CD8-IL2 broadly armed intratumoral CD8+ T cells with enhanced effector capacity, thereby specifically enabling reinvigoration of the dysfunctional T-cell pool to elicit potent immune activity. Notably, the revival of dysfunctional T cells to mediate effector activity by CD8-IL2 depended on simultaneous antigen recognition and was quantitatively and qualitatively superior to that achieved by PD-1 blockade. Finally, CD8-IL2 was able to functionally reinvigorate T cells in tumors resistant to anti-PD-1, underscoring its potential as a novel treatment strategy for patients with cancer. Significance: Reinvigorating T cells is crucial for response to checkpoint blockade therapy. However, emerging evidence suggests that the PD-1/PD-L1 axis is not the sole impediment for activating T cells within tumors. Selectively targeting cytokines toward specific T-cell subsets might overcome these barriers and stimulate T cells within resistant tumors. See related article by Moynihan et al., p. 1206 (32).

IL2 Targeted to CD8+ T Cells Promotes Robust Effector T-cell Responses and Potent Antitumor Immunity

IL2 signals pleiotropically on diverse cell types, some of which contribute to therapeutic activity against tumors, whereas others drive undesired activity, such as immunosuppression or toxicity. We explored the theory that targeting of IL2 to CD8+ T cells, which are key antitumor effectors, could enhance its therapeutic index. To this aim, we developed AB248, a CD8 cis-targeted IL2 that demonstrates over 500-fold preference for CD8+ T cells over natural killer and regulatory T cells (Tregs), which may contribute to toxicity and immunosuppression, respectively. AB248 recapitulated IL2's effects on CD8+ T cells in vitro and induced selective expansion of CD8+T cells in primates. In mice, an AB248 surrogate demonstrated superior antitumor activity and enhanced tolerability as compared with an untargeted IL2Rβγ agonist. Efficacy was associated with the expansion and phenotypic enhancement of tumor-infiltrating CD8+ T cells, including the emergence of a "better effector" population. These data support the potential utility of AB248 in clinical settings. Significance: The full potential of IL2 therapy remains to be unlocked. We demonstrate that toxicity can be decoupled from antitumor activity in preclinical models by limiting IL2 signaling to CD8+ T cells, supporting the development of CD8+ T cell-selective IL2 for the treatment of cancer. See related article by Kaptein et al. p. 1226.

Targeting a disintegrin and metalloprotease (ADAM) 17-CD122 axis enhances CD8+ T cell effector differentiation and anti-tumor immunity

CD8+ T cell immune responses are regulated by multi-layer networks, while the post-translational regulation remains largely unknown. Transmembrane ectodomain shedding is an important post-translational process orchestrating receptor expression and signal transduction through proteolytic cleavage of membrane proteins. Here, by targeting the sheddase A Disintegrin and Metalloprotease (ADAM)17, we defined a post-translational regulatory mechanism mediated by the ectodomain shedding in CD8+ T cells. Transcriptomic and proteomic analysis revealed the involvement of post-translational regulation in CD8+ T cells. T cell-specific deletion of ADAM17 led to a dramatic increase in effector CD8+ T cell differentiation and enhanced cytolytic effects to eliminate pathogens and tumors. Mechanistically, ADAM17 regulated CD8+ T cells through cleavage of membrane CD122. ADAM17 inhibition led to elevated CD122 expression and enhanced response to IL-2 and IL-15 stimulation in both mouse and human CD8+ T cells. Intriguingly, inhibition of ADAM17 in CD8+ T cells improved the efficacy of chimeric antigen receptor (CAR) T cells in solid tumors. Our findings reveal a critical post-translational regulation in CD8+ T cells, providing a potential therapeutic strategy of targeting ADAM17 for effective anti-tumor immunity.

MB2033, an anti-PD-L1 × IL-2 variant fusion protein, demonstrates robust anti-tumor efficacy with minimal peripheral toxicity

Interleukin-2 (IL-2), a cytokine with pleiotropic immune effects, was the first approved cancer immunotherapy agent. However, IL-2 is associated with systemic toxicity due to binding with its ligand IL-2Rα, such as vascular leakage syndrome, limiting its clinical applications. Despite efforts to extend the half-life of IL-2 and abolish IL-2Rα interactions, the risk of toxicity remains unresolved. In this study, we developed the bispecific fusion protein MB2033, comprising a novel IL-2 variant (IL-2v) connected to anti-programmed death ligand 1 (PD-L1) via a silenced Fc domain. The IL-2v of MB2033 exhibits attenuated affinity for IL-2Rβγ without binding to IL-2Rα. The binding affinity of MB2033 for PD-L1 is greater than that for IL-2Rβγ, indicating its preferential targeting of PD-L1+ tumor cells to induce tumor-specific immune activation. Accordingly, MB2033 exhibited significantly reduced regulatory T cell activation, while inducing comparable CD8+ T cell activation to recombinant human IL-2 (rhIL-2). MB2033 induced lower immune cell expansion and reduced cytokine levels compared with rhIL-2 in human peripheral blood mononuclear cells, indicating a decreased risk of peripheral toxicity. MB2033 exhibited superior anti-tumor efficacy, including tumor growth inhibition and complete responses, compared with avelumab monotherapy in an MC38 syngeneic mouse model. In normal mice, MB2033 was safer than non-α IL-2v and tolerable up to 30 mg/kg. These preclinical results provide evidence of the dual advantages of MB2033 with an enhanced safety and potent clinical efficacy for cancer treatment.

Anti-PD-1 cis-delivery of low-affinity IL-12 activates intratumoral CD8+T cells for systemic antitumor responses

Immune checkpoint blockade (ICB) therapies function by alleviating immunosuppression on tumor-infiltrating lymphocytes (TILs) but are often insufficient to fully reactivate these dysfunctional TILs. Although interleukin 12 (IL-12) has been used in combination with ICB to improve efficacy, this remains limited by severe toxicity associated with systemic administration of this cytokine. Here, we engineer a fusion protein composed of an anti-PD-1 antibody and a mouse low-affinity IL-12 mutant-2 (αPD1-mIL12mut2). Systemic administration of αPD1-mIL12mut2 displays robust antitumor activities with undetectable toxicity. Mechanistically, αPD1-mIL12mut2 preferentially activates tumor-infiltrating PD-1+CD8+T cells via high-affinity αPD-1 mediated cis-binding of low-affinity IL-12. Additionally, αPD1-mIL12mut2 treatment exerts an abscopal effect to suppress distal tumors, as well as metastasis. Collectively, αPD1-mIL12mut2 treatment induces robust systemic antitumor responses with reduced side effects.

The transcriptional landscape of cancer stem-like cell functionality in breast cancer

BACKGROUND

Cancer stem-like cells (CSCs) have been extensively researched as the primary drivers of therapy resistance and tumor relapse in patients with breast cancer. However, due to lack of specific molecular markers, increased phenotypic plasticity and no clear clinicopathological features, the assessment of CSCs presence and functionality in solid tumors is challenging. While several potential markers, such as CD24/CD44, have been proposed, the extent to which they truly represent the stem cell potential of tumors or merely provide static snapshots is still a subject of controversy. Recent studies have highlighted the crucial role of the tumor microenvironment (TME) in influencing the CSC phenotype in breast cancer. The interplay between the tumor and TME induces significant changes in the cancer cell phenotype, leading to the acquisition of CSC characteristics, therapeutic resistance, and metastatic spread. Simultaneously, CSCs actively shape their microenvironment by evading immune surveillance and attracting stromal cells that support tumor progression.

METHODS

In this study, we associated in vitro mammosphere formation assays with bulk tumor microarray profiling and deconvolution algorithms to map CSC functionality and the microenvironmental landscape in a large cohort of 125 breast tumors.

RESULTS

We found that the TME score was a significant factor associated with CSC functionality. CSC-rich tumors were characterized by an immune-suppressed TME, while tumors devoid of CSC potential exhibited high immune infiltration and activation of pathways involved in the immune response. Gene expression analysis revealed IFNG, CXCR5, CD40LG, TBX21 and IL2RG to be associated with the CSC phenotype and also displayed prognostic value for patients with breast cancer.

CONCLUSION

These results suggest that the characterization of CSCs content and functionality in tumors can be used as an attractive strategy to fine-tune treatments and guide clinical decisions to improve patients therapy response.

Next-generation anti-PD-L1/IL-15 immunocytokine elicits superior antitumor immunity in cold tumors with minimal toxicity

The clinical applications of immunocytokines are severely restricted by dose-limiting toxicities. To address this challenge, here we propose a next-generation immunocytokine concept involving the design of LH05, a tumor-conditional anti-PD-L1/interleukin-15 (IL-15) prodrug. LH05 innovatively masks IL-15 with steric hindrance, mitigating the "cytokine sink" effect of IL-15 and reducing systemic toxicities associated with wild-type anti-PD-L1/IL-15. Moreover, upon specific proteolytic cleavage within the tumor microenvironment, LH05 releases an active IL-15 superagonist, exerting potent antitumor effects. Mechanistically, the antitumor efficacy of LH05 depends on the increased infiltration of CD8+ T and natural killer cells by stimulating the chemokines CXCL9 and CXCL10, thereby converting cold tumors into hot tumors. Additionally, the tumor-conditional anti-PD-L1/IL-15 can synergize with an oncolytic virus or checkpoint blockade in advanced and metastatic tumor models. Our findings provide a compelling proof of concept for the development of next-generation immunocytokines, contributing significantly to current knowledge and strategies of immunotherapy.

Facts and Hopes on Chimeric Cytokine Agents for Cancer Immunotherapy

Cytokines are key mediators of immune responses that can modulate the antitumor activity of immune cells. Cytokines have been explored as a promising cancer immunotherapy. However, there are several challenges to cytokine therapy, especially a lack of tumor targeting, resulting in high toxicity and limited efficacy. To overcome these limitations, novel approaches have been developed to engineer cytokines with improved properties, such as chimeric cytokines. Chimeric cytokines are fusion proteins that combine different cytokine domains or link cytokines to antibodies (immunocytokines) or other molecules that can target specific receptors or cells. Chimeric cytokines can enhance the selectivity and stability of cytokines, leading to reduced toxicity and improved efficacy. In this review, we focus on two promising cytokines, IL2 and IL15, and summarize the current advances and challenges of chimeric cytokine design and application for cancer immunotherapy. Most of the current approaches focus on increasing the potency of cytokines, but another important goal is to reduce toxicity. Cytokine engineering is promising for cancer immunotherapy as it can enhance tumor targeting while minimizing adverse effects.

Exploiting the immune system in hepatic tumor targeting: Unleashing the potential of drugs, natural products, and nanoparticles

Hepatic tumors present a formidable challenge in cancer therapeutics, necessitating the exploration of novel treatment strategies. In recent years, targeting the immune system has attracted interest to augment existing therapeutic efficacy. The immune system in hepatic tumors includes numerous cells with diverse actions. CD8+ T lymphocytes, T helper 1 (Th1) CD4+ T lymphocytes, alternative M1 macrophages, and natural killer (NK) cells provide the antitumor immunity. However, Foxp3+ regulatory CD4+ T cells (Tregs), M2-like tumor-associated macrophages (TAMs), and myeloid-derived suppressor cells (MDSCs) are the key immune inhibitor cells. Tumor stroma can also affect these interactions. Targeting these cells and their secreted molecules is intriguing for eliminating malignant cells. The current review provides a synopsis of the immune system components involved in hepatic tumor expansion and highlights the molecular and cellular pathways that can be targeted for therapeutic intervention. It also overviews the diverse range of drugs, natural products, immunotherapy drugs, and nanoparticles that have been investigated to manipulate immune responses and bolster antitumor immunity. The review also addresses the potential advantages and challenges associated with these approaches.

rhIL-7-hyFc and hIL-2/TCB2c combination promotes an immune-stimulatory tumor microenvironment that improves antitumor efficacy of checkpoint inhibitors

BACKGROUND

Recombinant human interleukin (rhIL)-7-hyFc (efineptakin alfa; NT-I7) is a potent T-cell amplifier, with two IL-7 molecules fused to IgD/IgG4 elements. rhIL-7-hyFc promotes extensive infiltration of CD8+ T cells into the tumor, concurrently increasing the numbers of intratumoral PD-1+CD8+ T cells. The hIL-2/TCB2 complex (SLC-3010) inhibits tumor growth by preferential activation of CD122 (IL-2Rβ)high CD8+ T cells and natural killer cells, over regulatory T cells (Tregs). We investigated the underlying mechanisms of rhIL-7-hyFc and hIL-2/TCB2c antitumor activity and the potential synergistic efficacy, specifically focusing on tumor-specific CD8+ cells within the tumor and the tumor-draining lymph nodes (tdLN).

METHODS

MC38 and CT26 tumor-bearing mice were administered with 10 mg/kg rhIL-7-hyFc intramuscularly and 0.9 mg/kg hIL-2/TCB2c intravenously. Anti-PD-1 monoclonal antibody was administered intraperitoneally three times at 3-day intervals at a dose of 5 mg/kg. Tumor volume was measured to assess efficacy. To compare the composition of immune cells between each monotherapy and the combination therapy, we analyzed tumors and tdLNs by flow cytometry.

RESULTS

Our data demonstrate that the combination of rhIL-7-hyFc and hIL-2/TCB2c increases efficacy and generates an immune-stimulatory tumor microenvironment (TME). The TME is characterized by an increased infiltration of tumor-specific CD8+ T cells, and a decreased frequency of CD39highTIM-3+ Treg cells. Most importantly, rhIL-7-hyFc increases infiltration of a CD62L+Ly108+ early progenitor population of exhausted CD8+ T cells (TPEX), which may retain long-term proliferation capacity and replenish functional effector CD8+ T cells. hIL-2/TCB2c induces differentiation of CD62L+Ly108+ TPEX rapidly into CD101+ terminally differentiated subsets (terminally exhausted T cell (TEX term)). Our study also demonstrates that rhIL-7-hyFc significantly enhances the proliferation rate of TPEX in the tdLNs, positively correlating with their abundance within the tumor. Moreover, rhIL-7-hyFc and hIL-2/TCB2c can overcome the limited therapeutic effectiveness of PD-1 blockade, culminating in the complete regression of tumors.

CONCLUSIONS

rhIL-7-hyFc can expand and maintain the progenitor pool of exhausted CD8+ T cells, whereas hIL-2/TCB2c promotes their differentiation into TEX term. Together, this induces an immune-stimulatory TME that improves the efficacy of checkpoint blockade.

Immunocytokines with target cell-restricted IL-15 activity for treatment of B cell malignancies

Despite the advances in cancer treatment achieved, for example, by the CD20 antibody rituximab, an urgent medical need remains to optimize the capacity of such antibodies to induce antibody-dependent cellular cytotoxicity (ADCC) that determines therapeutic efficacy. The cytokine IL-15 stimulates proliferation, activation, and cytolytic capacity of NK cells, but broad clinical use is prevented by short half-life, poor accumulation at the tumor site, and severe toxicity due to unspecific immune activation. We here report modified immunocytokines consisting of Fc-optimized CD19 and CD20 antibodies fused to an IL-15 moiety comprising an L45E-E46K double mutation (MIC+ format). The E46K mutation abrogated binding to IL-15Rα, thereby enabling substitution of physiological trans-presentation by target binding and thus conditional IL-15Rβγ stimulation, whereas the L45E mutation optimized IL-15Rβγ agonism and producibility. In vitro analysis of NK activation, anti-leukemia reactivity, and toxicity using autologous and allogeneic B cells confirmed target-dependent function of MIC+ constructs. Compared with Fc-optimized CD19 and CD20 antibodies, MIC+ constructs mediated superior target cell killing and NK cell proliferation. Mouse models using luciferase-expressing human NALM-6 lymphoma cells, patient acute lymphoblastic leukemia (ALL) cells, and murine EL-4 lymphoma cells transduced with human CD19/CD20 as targets and human and murine NK cells as effectors, respectively, confirmed superior and target-dependent anti-leukemic activity. In summary, MIC+ constructs combine the benefits of Fc-optimized antibodies and IL-15 cytokine activity and mediate superior NK cell immunity with potentially reduced side effects. They thus constitute a promising new immunotherapeutic approach shown here for B cell malignancies.

Radiation Synergizes with IL2/IL15 Stimulation to Enhance Innate Immune Activation and Antitumor Immunity

Ionizing radiation is known to possess immune modulatory properties. However, how radiotherapy (RT) may complement with different types of immunotherapies to boost antitumor responses is unclear. In mice implanted with EO771 syngeneic tumors, NL-201 a stable, highly potent CD25-independent agonist to IL2 and IL15 receptors with enhanced affinity for IL2Rβγ was given with or without RT. Flow analysis and Western blot analysis was performed to determine the mechanisms involved. STING (-/-) and CD11c+ knockout mice were implanted with EO771 tumors to confirm the essential signaling and cell types required to mediate the effects seen. Combination of RT and NL-201 to enhance systemic immunotherapy with an anti-PD-1 checkpoint inhibitor was utilized to determine tumor growth inhibition and survival, along characterization of tumor microenvironment as compared with all other treatment groups. Here, we showed that RT, synergizing with NL-201 produced enhanced antitumor immune responses in murine breast cancer models. When given together, RT and NL-201 enhanced activation of the cytosolic DNA sensor cyclic GMP-AMP synthase-stimulator of IFN genes (cGAS-STING) pathway, resulting in increased type I IFN production in dendritic cells (DC), and consequently greater tumor infiltration and more efficient priming of antigen-specific T cells. The immune stimulatory mechanisms triggered by NL-201 and RT resulted in superior tumor growth inhibition and survival benefit in both localized and metastatic cancers. Our results support further preclinical and clinical investigation of this novel synergism regimen in locally advanced and metastatic settings.

Molecular Engineering of Interleukin-2 for Enhanced Therapeutic Activity in Autoimmune Diseases

The interleukin-2 (IL-2) cytokine plays a crucial role in regulating immune responses and maintaining immune homeostasis. Its immunosuppressive effects have been harnessed therapeutically via administration of low cytokine doses. Low-dose IL-2 has shown promise in the treatment of various autoimmune and inflammatory diseases; however, the clinical use of IL-2 is complicated by its toxicity, its pleiotropic effects on both immunostimulatory and immunosuppressive cell subsets, and its short serum half-life, which collectively limit the therapeutic window. As a result, there remains a considerable need for IL-2-based autoimmune disease therapies that can selectively target regulatory T cells with minimal off-target binding to immune effector cells in order to prevent cytokine-mediated toxicities and optimize therapeutic efficacy. In this review, we discuss exciting advances in IL-2 engineering that are empowering the development of novel therapies to treat autoimmune conditions. We describe the structural mechanisms of IL-2 signaling, explore current applications of IL-2-based compounds as immunoregulatory interventions, and detail the progress and challenges associated with clinical adoption of IL-2 therapies. In particular, we focus on protein engineering approaches that have been employed to optimize the regulatory T-cell bias of IL-2, including structure-guided or computational design of cytokine mutants, conjugation to polyethylene glycol, and the development of IL-2 fusion proteins. We also consider future research directions for enhancing the translational potential of engineered IL-2-based therapies. Overall, this review highlights the immense potential to leverage the immunoregulatory properties of IL-2 for targeted treatment of autoimmune and inflammatory diseases.

Tumor-localized interleukin-2 and interleukin-12 combine with radiation therapy to safely potentiate regression of advanced malignant melanoma in pet dogs

The clinical use of interleukin-2 and -12 cytokines against cancer is limited by their narrow therapeutic windows due to on-target, off-tumor activation of immune cells when delivered systemically. Engineering IL-2 and IL-12 to bind to extracellular matrix collagen allows these cytokines to be retained within tumors after intralesional injection, overcoming these clinical safety challenges. While this approach has potentiated responses in syngeneic mouse tumors without toxicity, the complex tumor-immune interactions in human cancers are difficult to recapitulate in mouse models of cancer. This has driven an increased role for comparative oncology clinical trials in companion (pet) dogs with spontaneous cancers that feature analogous tumor and immune biology to human cancers. Here, we report the results from a dose-escalation clinical trial of intratumoral collagen-binding IL-2 and IL-12 cytokines in pet dogs with malignant melanoma, observing encouraging local and regional responses to therapy that may suggest human clinical benefit with this approach.

The combination of IL-2 nanoparticles and Palbociclib enhances the anti-tumor immune response for colon cancer therapy

Immunotherapy of tumors plays a pivotal role in the current treatment of cancer. While interleukin 2 (IL-2) demonstrated its efficacy as an immunotherapeutic drug in the early days, its short blood circulation time poses challenges in maintaining effective therapeutic concentrations. Additionally, IL-2's activation of regulatory T cells can counteract its anti-cancer effects. Therefore, the primary goal of this study was to formulate IL-2-carrying nanoparticles via boron-nitrogen coordination between methoxy poly (ethylene glycol) block poly-[(N-2-hydroxyethyl)-aspartamide]phenylboronic acid (mPEG-b-PHEA-PBA, P-PBA) and poly (L-lysine) (PLL). These nanoparticles are intended to be used in combination with CDK4/6 inhibitors to address the short blood circulation time of IL-2, reduce its immunosuppressive effects, and enhance the overall immune response. The envisaged outcome is a sustained and potent therapeutic effect, offering a novel and promising combination therapy strategy for tumor immunotherapy.

Celastrol, which targets IL-2/CD25 binding inhibition, induces T cell-mediated antitumor activity in melanoma

Interleukin-2 (IL-2) induces contrasting immune responses depending on its binding receptor subunit; thus, selective receptor binding is considered a key challenge in cancer therapeutic strategies. In this study, we aimed to investigate the inhibition of IL-2 action and antitumor activity of celastrol (CEL), a compound identified in a screen for IL-2/CD25 binding inhibitors, and to elucidate the underlying role of CEL in immune cells. We found that CEL selectively impairs the binding of IL-2 and CD25 and directly binds to IL-2 but not to CD25. CEL significantly suppressed the proliferation and signaling of IL-2-dependent murine T cells and interfered with IL-2-responsive STAT5 phosphorylation in IL-2 reporter cells and human PBMCs. After confirming the impact of CEL on IL-2, we evaluated its antitumor activity in C57BL/6 mice bearing B16F10 tumors and found that CEL significantly inhibited tumor growth by increasing CD8+ T cells. We also found that CEL did not inhibit tumor growth in T cell-deficient BALB/c nude mice, suggesting that its activity was mediated by the T-cell response. Moreover, combination therapy with low-dose CEL and a TNFR2 antagonist synergistically improved the therapeutic efficacy of the individual monotherapies by increasing the ratio of intratumoral CD8/Treg cells and suppressing Foxp3 expression. These findings suggest that CEL, which inhibits CD25 binding by targeting IL-2, exerts antitumor activity by mediating the T-cell response and could be a promising candidate for combination therapy in cancer immunotherapy against melanoma.

Recent advances in stimuli-responsive tailored nanogels for cancer therapy; from bench to personalized treatment

To improve the quality of health in a personalized manner, better control over pharmacologically relevant cargo formulation, organ-specific targeted delivery, and on-demand release of therapeutic agents is crucial. Significant work has been put into designing and developing revolutionary nanotherapeutics approaches for the effective monitoring and personalized treatment of disease. Nanogel (NG) has attracted significant interest because of its tremendous potential in cancer therapy and its environmental stimuli responsiveness. NG is considered a next-generation delivery technology due to its benefits like as size tunability, high loading, stimuli responsiveness, prolonged drug release via in situ gelling mechanisms, stability, and its potential to provide personalized therapy from the investigation of human genes and the genes in various types of cancers and its association with a selective anticancer drug. Stimuli-responsive NGs can be used as smart nanomedicines to detect and treat cancer and can be tuned as personalized medicine as well. This comprehensive review article's major objectives include the challenges of NGs' clinical translation for cancer treatment as well as its early preclinical successes and prospects.

Specific Targeting of Zinc Transporter LIV-1 with Immunocytokine Containing Anti-LIV-1 VHH and Human IL-2 and Evaluation of its In vitro Antitumor Activity

BACKGROUND

Interleukin 2 (IL-2) is a vital cytokine in the induction of T and NK cell responses, the proliferation of CD8+ T cells, and the effective treatment of human cancers such as melanoma and renal cell carcinoma. However, widespread use of this cytokine is limited due to its short half-life, severe toxicity, lack of specific tumor targeting, and activation of Treg cells mediated by high-affinity interleukin-2 receptors.

OBJECTIVE

In this study, a tumor-targeting LIV-1 VHH-mutIL2 immunocytokine with reduced CD25 (α chain of the high-affinity IL-2 receptor) binding activity was developed to improve IL-2 half-life by decreasing its renal infiltration in comparison with wild and mutant IL-2 molecules.

METHODS

The recombinant immunocytokine was designed and expressed. The biological activity of the purified fusion protein was investigated in in vitro and in vivo experiments.

RESULTS

The fusion protein represented specific binding to MCF7 (the breast cancer cell line) and more efficient cytotoxicity than wild-type IL-2 and mutant IL-2. The PK parameters of the recombinant immunocytokine were also improved in comparison to the IL-2 molecules.

CONCLUSION

The observed results showed that LIV1-mIL2 immunocytokine could be considered as an effective agent in the LIV-1-targeted treatment of cancers due to its longer half-life and stronger cytotoxicity.

Targeting anticancer immunity in oral cancer: Drugs, products, and nanoparticles

Oral cavity carcinomas are the most frequent malignancies among head and neck malignancies. Oral tumors include not only oral cancer cells with different potency and stemness but also consist of diverse cells, containing anticancer immune cells, stromal and also immunosuppressive cells that influence the immune system reactions. The infiltrated T and natural killer (NK) cells are the substantial tumor-suppressive immune compartments in the tumor. The infiltration of these cells has substantial impacts on the response of tumors to immunotherapy, chemotherapy, and radiotherapy. Nevertheless, cancer cells, stromal cells, and some other compartments like regulatory T cells (Tregs), macrophages, and myeloid-derived suppressor cells (MDSCs) can repress the immune responses against malignant cells. Boosting anticancer immunity by inducing the immune system or repressing the tumor-promoting cells is one of the intriguing approaches for the eradication of malignant cells such as oral cancers. This review aims to concentrate on the secretions and interactions in the oral tumor immune microenvironment. We review targeting tumor stroma, immune system and immunosuppressive interactions in oral tumors. This review will also focus on therapeutic targets and therapeutic agents such as nanoparticles and products with anti-tumor potency that can boost anticancer immunity in oral tumors. We also explain possible future perspectives including delivery of various cells, natural products and drugs by nanoparticles for boosting anticancer immunity in oral tumors.

Boosting cytotoxicity of adoptive allogeneic NK cell therapy with an oncolytic adenovirus encoding a human vIL-2 cytokine for the treatment of human ovarian cancer

Despite good results in the treatment of hematological malignancies, Natural killer (NK) cells have shown limited effectiveness in solid tumors, such as ovarian cancer (OvCa). Here, we assessed the potential of an oncolytic adenovirus expressing a variant interleukin-2 (vIL-2) cytokine, Ad5/3-E2F-d24-vIL2 (vIL-2 virus), also known as TILT-452, to enhance NK cell therapy efficacy in human OvCa ex vivo. Human OvCa surgical specimens were processed into single-cell suspensions and NK cells were expanded from healthy blood donors. OvCa sample digests were co-cultured ex vivo with NK cells and vIL-2 virus and cancer cell killing potential assessed in real time through cell impedance measurement. Proposed therapeutic combination was evaluated in vivo with an OvCa patient-derived xenograft (PDX) in mice. Addition of vIL-2 virus significantly enhanced NK cell therapy killing potential in treated OvCa co-cultures. Similarly, vIL-2 virus in combination with NK cell therapy promoted the best in vivo OvCa tumor control. Mechanistically, vIL-2 virus induced higher percentages of granzyme B in NK cells, and CD8+ T cells, while T regulatory cell proportions remained comparable to NK cell monotherapy in vivo. Ad5/3-E2F-d24-vIL2 virus treatment represents a promising strategy to boost adoptive NK cell therapeutic effect in human OvCa.

An engineered immunocytokine with collagen affinity improves the tumor bioavailability, tolerability, and therapeutic efficacy of IL-2

The clinical utility of human interleukin-2 (hIL-2) is limited by its short serum half-life, preferential activation of regulatory T (TReg) over immune effector cells, and dose-limiting toxicities. We previously engineered F10 immunocytokine (IC), an intramolecularly assembled cytokine/antibody fusion protein that linked hIL-2 to an anti-IL-2 antibody (denoted F10) that extended IL-2 half-life and augmented the immune effector to TReg ratio. Here, we leveraged molecular engineering to improve the anti-tumor therapeutic efficacy and tolerability of F10 IC by developing an iteration, denoted F10 IC-CBD (collagen binding domain), designed for intratumoral administration and in situ retention based on collagen affinity. F10 IC-CBD retained IL-2 bioactivity exclusively in the tumor and eliminated IL-2-associated toxicities. Furthermore, F10 IC exhibited potent single-agent therapeutic efficacy and synergy with systemic immune checkpoint blockade and elicited an abscopal response in mouse tumors models. This engineered fusion protein presents a prototype for the design of intratumoral therapies.

Sonodynamic Cytokine Nanocomplexes with Specific Stimulation towards Effector T Cell for Combination Cancer Immunotherapy

Cytokine therapy mediates the interaction between immune cells and non-immune cells in the tumor microenvironment (TME), forming a promising approach in cancer therapy. However, the dose-dependent adverse effects and non-selective stimulation of cytokines limit their clinical use. We herein report a sonodynamic cytokine nano-immunocomplex (SPNAI ) that specifically activates effector T cells (Teffs) for antitumor immunotherapy. By conjugating anti-interleukin-2 (anti-IL-2) antibodies S4B6 on the semiconducting polymer nanoparticles to afford SPNA , this nanoantibody SPNA can bind with IL-2 to form SPNAI which can block the interaction between IL-2 and regulatory T cells (Tregs), selectively activating Teffs in TME. Moreover, SPNAI generates 1 O2 to trigger immunogenic cell death of cancer cells upon sono-irradiation, which promotes the maturation of dendritic cells and the proliferation of Teffs. This SPNAI -mediated combination sonodynamic immunotherapy thus elevates the ratio of Teffs/Tregs in TME, resulting in inhibition of tumor growth, suppression of lung metastasis and prevention of tumor relapse.

Blocking of oestrogen signals improves anti-tumour effect regardless of oestrogen receptor alpha expression in cancer cells

BACKGROUND

Anti-oestrogenic therapy has been used for breast cancer patients with oestrogen susceptibility cancer cells. However, little has been known about its potential role for immune cell biology within TME, particularly in cancer patients without oestrogen sensitivity of tumour cells. Therefore, we aimed to study the effect of oestrogen on immunity within TME.

METHODS

Using a clinical dataset, immune cells of humans and mice, female mice with and without ovaries, and several murine ERα-negative cancer cell lines, we evaluated the effect of oestrogen on immunity in TME.

RESULTS

Clinical data analysis suggested oestrogen's suppressive efficacy against CTLs. Additionally, in vitro and in vivo experiments revealed intra-tumoural CTLs' direct repressive action by oestrogen in both mice and humans; blockade of oestrogen signals cancelled its immunosuppression resulting in tumour growth reduction in vivo. Most notably, immunotherapy (immune checkpoint inhibitor; ICI) combined with anti-oestrogenic therapy exhibited a dramatic anti-tumour effect.

CONCLUSIONS

This study provides novel insights into how oestrogen contributes to tumour progression and a therapeutic rationale for blocking oestrogen signalling to boost the anti-tumour effect of ICI, regardless of tumour cells' ERα expression.

Role of DNA Methylation Profiles as Potential Biomarkers and Novel Therapeutic Targets in Head and Neck Cancer

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide and is associated with high mortality. The main reasons for treatment failure are a low rate of early diagnosis, high relapse rates, and distant metastasis with poor outcomes. These are largely due to a lack of diagnostic, prognostic, and predictive biomarkers in HNSCC. DNA methylation has been demonstrated to play an important role in the pathogenesis of HNSCC, and recent studies have also valued DNA methylation as a potential biomarker in HNSCC. This review summarizes the current knowledge on DNA methylation profiles in HPV-positive and HPV-negative HNSCC and how these may contribute to the pathogenesis of HNSCC. It also summarizes the potential value of DNA methylation as a biomarker in the diagnosis, prognosis, and prediction of the response to therapy. With the recent immunotherapy era in head and neck treatment, new strategies to improve immune responses by modulating TIMEs have been intensely investigated in early-phase trials. Therefore, this study additionally summarizes the role of DNA methylation in the regulation of TIMEs and potential predictive immunotherapy response biomarkers. Finally, this study reviews ongoing clinical trials using DNA methylation inhibitors in HNSCC.

CU06-1004 as a promising strategy to improve anti-cancer drug efficacy by preventing vascular leaky syndrome

Background: Interleukin-2 (IL-2) is the first cancer therapeutic agent with an immunomodulatory function. Although it has been experimentally proven to be effective against metastatic renal cell carcinoma and metastatic melanoma, the clinical application of high-dose IL-2 (HDIL-2) has been limited because of its short half-life and severe side effects, such as vascular leakage syndrome (VLS) or capillary leaky syndrome (CLS). However, methods for overcoming this issue have not yet been identified. Methods: We discovered CU06-1004, an endothelial dysfunction blocker, through a previous study, and co-treated with IL-2 immunotherapy to confirm its inhibitory effect on HDIL-2-induced endothelial permeability. CU06-1004 was co-administered with HDIL-2 for 4 days in an in vivo mouse model. After drug injection, the mice were sacrificed, and Evans blue staining was performed. Results: In vitro, HDIL-2 treatment decreased HUVEC stability, which was rescued by co-treatment with CU06-1004. In our mouse model, co-administration of CU06-1004 and HDIL-2 prevented HDIL-2-induced vascular leakage by normalizing endothelial cells. Notably, the HDIL-2 and CU06-1004 combination therapy considerably reduced tumor growth in the B16F10 melanoma mouse model. Conclusion: Our data suggest that CU06-1004 acts as a potential anticancer drug candidate, not only by preventing HDIL-2-induced VLS but also by enhancing the anticancer effects of HDIL-2 immunotherapy.

Improving cancer immunotherapy via co-delivering checkpoint blockade and thrombospondin-1 downregulator

The use of checkpoint-blockade antibodies is still restricted in several malignancies due to the modest efficacy, despite considerable success in anti-tumor immunotherapy. The poor response of cancer cells to immune destruction is an essential contributor to the failure of checkpoint therapy. We hypothesized that combining checkpoint therapy with natural-product chemosensitizer could enhance immune response. Herein, a targeted diterpenoid derivative was integrated with the checkpoint blockade (anti-CTLA-4) to improve immunotherapy using thermosensitive liposomes as carriers. In vivo, the liposomes enabled the co-delivery of the two drug payloads into the tumor. Consequently, the regulatory T cell proliferation was restrained, the cytotoxic T cell infiltration was enhanced, and the profound immunotherapeutic effect was achieved. In addition, the immunotherapeutic effect of another clinically used checkpoint antibody, anti-PD-1, also benefited from the diterpenoid derivative. Of note, our mechanism study revealed that the targeted diterpenoid derivative increased the sensitivity of cancer cells to immune attack via THBS1 downregulation and the resultant destruction of THBS1-CD47 interaction. Collectively, co-delivering THBS1 inhibitor and checkpoint blockade is promising to boost cancer immunotherapy. We first time discovered that THBS1 suppression could strengthen checkpoint therapy.

Reigniting hope in cancer treatment: the promise and pitfalls of IL-2 and IL-2R targeting strategies

Interleukin-2 (IL-2) and its receptor (IL-2R) are essential in orchestrating immune responses. Their function and expression in the tumor microenvironment make them attractive targets for immunotherapy, leading to the development of IL-2/IL-2R-targeted therapeutic strategies. However, the dynamic interplay between IL-2/IL-2R and various immune cells and their dual roles in promoting immune activation and tolerance presents a complex landscape for clinical exploitation. This review discusses the pivotal roles of IL-2 and IL-2R in tumorigenesis, shedding light on their potential as diagnostic and prognostic markers and their therapeutic manipulation in cancer. It underlines the necessity to balance the anti-tumor activity with regulatory T-cell expansion and evaluates strategies such as dose optimization and selective targeting for enhanced therapeutic effectiveness. The article explores recent advancements in the field, including developing genetically engineered IL-2 variants, combining IL-2/IL-2R-targeted therapies with other cancer treatments, and the potential benefits of a multidimensional approach integrating molecular profiling, immunological analyses, and clinical data. The review concludes that a deeper understanding of IL-2/IL-2R interactions within the tumor microenvironment is crucial for realizing the full potential of IL-2-based therapies, heralding the promise of improved outcomes for cancer patients.

In Situ Vaccination Following Intratumoral Injection of IL2 and Poly-l-lysine/Iron Oxide/CpG Nanoparticles to a Radiated Tumor Site

The in situ vaccine effect of radiation therapy (RT) has been shown to be limited in both preclinical and clinical settings, possibly due to the inadequacy of RT alone to stimulate in situ vaccination in immunologically "cold" tumor microenvironments (TMEs) and the mixed effects of RT in promoting tumor infiltration of both effector and suppressor immune cells. To address these limitations, we combined intratumoral injection of the radiated site with IL2 and a multifunctional nanoparticle (PIC). The local injection of these agents produced a cooperative effect that favorably immunomodulated the irradiated TME, enhancing the activation of tumor-infiltrating T cells and improving systemic anti-tumor T cell immunity. In syngeneic murine tumor models, the PIC+IL2+RT combination significantly improved the tumor response, surpassing the single or dual combinations of these treatments. Furthermore, this treatment led to the activation of tumor-specific immune memory and improved abscopal effects. Our findings suggest that this strategy can be used to augment the in situ vaccine effect of RT in clinical settings.

Expansion of circulating stem-like CD8+ T cells by adding CD122-directed IL-2 complexes to radiation and anti-PD1 therapies in mice

Combination of radiation therapy (RT) with immune checkpoint blockade can enhance systemic anti-tumor T cell responses. Here, using two mouse tumor models, we demonstrate that adding long-acting CD122-directed IL-2 complexes (IL-2c) to RT/anti-PD1 further increases tumor-specific CD8+ T cell numbers. The highest increase (>50-fold) is found in the blood circulation. Compartmental analysis of exhausted T cell subsets shows that primarily undifferentiated, stem-like, tumor-specific CD8+ T cells expand in the blood; these cells express the chemokine receptor CXCR3, which is required for migration into tumors. In tumor tissue, effector-like but not terminally differentiated exhausted CD8+ T cells increase. Consistent with the surge in tumor-specific CD8+ T cells in blood that are migration and proliferation competent, we observe a CD8-dependent and CXCR3-dependent enhancement of the abscopal effect against distant/non-irradiated tumors and find that CD8+ T cells isolated from blood after RT/anti-PD1/IL-2c triple treatment can be a rich source of tumor-specific T cells for adoptive transfers.

Oncolytic virotherapy: basic principles, recent advances and future directions

Oncolytic viruses (OVs) have attracted growing awareness in the twenty-first century, as they are generally considered to have direct oncolysis and cancer immune effects. With the progress in genetic engineering technology, OVs have been adopted as versatile platforms for developing novel antitumor strategies, used alone or in combination with other therapies. Recent studies have yielded eye-catching results that delineate the promising clinical outcomes that OVs would bring about in the future. In this review, we summarized the basic principles of OVs in terms of their classifications, as well as the recent advances in OV-modification strategies based on their characteristics, biofunctions, and cancer hallmarks. Candidate OVs are expected to be designed as "qualified soldiers" first by improving target fidelity and safety, and then equipped with "cold weapons" for a proper cytocidal effect, "hot weapons" capable of activating cancer immunotherapy, or "auxiliary weapons" by harnessing tactics such as anti-angiogenesis, reversed metabolic reprogramming and decomposing extracellular matrix around tumors. Combinations with other cancer therapeutic agents have also been elaborated to show encouraging antitumor effects. Robust results from clinical trials using OV as a treatment congruously suggested its significance in future application directions and challenges in developing OVs as novel weapons for tactical decisions in cancer treatment.

A split, conditionally active mimetic of IL-2 reduces the toxicity of systemic cytokine therapy

The therapeutic potential of recombinant cytokines has been limited by the severe side effects of systemic administration. We describe a strategy to reduce the dose-limiting toxicities of monomeric cytokines by designing two components that require colocalization for activity and that can be independently targeted to restrict activity to cells expressing two surface markers. We demonstrate the approach with a previously designed mimetic of cytokines interleukin-2 and interleukin-15-Neoleukin-2/15 (Neo-2/15)-both for trans-activating immune cells surrounding targeted tumor cells and for cis-activating directly targeted immune cells. In trans-activation mode, tumor antigen targeting of the two components enhanced antitumor activity and attenuated toxicity compared with systemic treatment in syngeneic mouse melanoma models. In cis-activation mode, immune cell targeting of the two components selectively expanded CD8+ T cells in a syngeneic mouse melanoma model and promoted chimeric antigen receptor T cell activation in a lymphoma xenograft model, enhancing antitumor efficacy in both cases.

Chlorin e6-associated photodynamic therapy enhances abscopal antitumor effects via inhibition of PD-1/PD-L1 immune checkpoint

We hypothesized that photodynamic therapy (PDT) with Chlorin e6 (Ce6) enhances antitumor abscopal effects via inhibition of the programmed cell death-1/programmed death-ligand 1 (PD-1/PD-L1) immune checkpoint. By using syngeneic melanoma and pancreatic tumor mouse models, we studied the Ce6-PDT-induced immune responses in local and distant tumor microenvironments. In addition, the Ce6-PDT's target in the PD-1/PD-L1 interaction was analyzed in MC38-hPD-L1 colon cancer and PD-1 expressing Jurkat T cell coculture. The tumors in the irradiated and non-irradiated sites in the abscopal effective (Abs_eff) group of both mouse models were regressed, proving the abscopal effect. The immunogenic effect in the Abs_eff group was associated with an expansion of T cell and other immune cells infiltration without changes in the CD39⁺ population in either the right or left tumors compared to control group. Furthermore, the abscopal ineffective (Abs_ineff) group demonstrated lesser increase of T cells, decreased immune cell infiltration, and increased CD39-expressing Treg cells without suppression of tumor growth. In the coculture with PD-1-expressing Jurkat T cell, Ce6-PDT efficiently suppressed the PD-1/PD-L1 interactions by increasing the proliferation and cytotoxic activity of CD8⁺ T cells while decreasing CD39-expressing Treg cells in a dose-dependent manner. Likewise, the inhibition of PD-1/PD-L1 interactions was also correlated with the increased production of IL-2 and Granzyme B. Our findings imply that Ce6-PDT is a promising immunotherapy with the potential to improve the abscopal effect.

Exopolysaccharides of Lactobacillus rhamnosus GG ameliorate Salmonella typhimurium-induced intestinal inflammation via the TLR4/NF-κB/MAPK pathway

BACKGROUND

Salmonella typhimurium (S.T), as an important foodborne bacterial pathogen, can cause diarrhea and gastroenteritis in humans and animals. Numerous studies have confirmed that exopolysaccharides (EPSs) have various biological functions, but the mechanism through which EPSs improve the immunity of animals against the invasion of pathogenic bacteria is unclear. Here, we explored the protective effect of EPSs of Lactobacillus rhamnosus GG (LGG) on the S.T-infected intestine.

METHODS

Mice received adequate food and drinking water for one week before the start of the experiment. After 7 d of prefeeding, 2×10⁸ CFU/mL S.T solution and an equivalent volume of saline (control group) were given orally for 1 d. On the fourth day, the mice were treated with 0.5 mg/mL EPSs, 1.0 mg/mL EPSs, 2.0 mg/mL EPSs, or 2.0 mg/mL penicillin for 7 d. Finally, the body and relative organ weight, histological staining, and the levels of antioxidant enzyme activity and inflammatory cytokines were determined.

RESULTS

The S.T-infected mice exhibited symptoms of decreased appetite, somnolence, diarrhea and flagging spirit. Treatment with EPSs and penicillin improved the weight loss of the mice, and the high dose of EPSs showed the best therapeutic effect. EPSs significantly ameliorated S.T-induced ileal injury in mice. High-dose EPSs were more effective than penicillin for alleviating ileal oxidative damage induced by S.T. The mRNA levels of inflammatory cytokines in the ileum of mice showed that the regulatory effects of EPSs on inflammatory cytokines were better than those of penicillin. EPSs could inhibit the expression and activation of key proteins of the TLR4/NF-κB/MAPK pathway and thereby suppress the level of S.T-induced ileal inflammation.

CONCLUSIONS

EPSs attenuate S.T-induced immune responses by inhibiting the expression of key proteins in the TLR4/NF-κB/MAPK signaling pathway. Moreover, EPSs could promote bacterial aggregation into clusters, which may be a potential strategy for reducing the bacterial invasion of intestinal epithelial cells.

Recent and future perspectives on engineering interferons and other cytokines as therapeutics

As crucial mediators and regulators of our immune system, cytokines are involved in a broad range of biological processes and are implicated in various disease pathologies. The field of cytokine therapeutics has gained much momentum from the maturation of conventional protein engineering methodologies such as structure-based designs and/or directed evolution, which is further aided by the advent of in silico protein designs and characterization. Just within the past 5 years, there has been an explosion of proof-of-concept, preclinical, and clinical studies that utilize an armory of protein engineering methods to develop cytokine-based drugs. Here, we highlight the key engineering strategies undertaken by recent studies that aim to improve the pharmacodynamic and pharmacokinetic profile of interferons and other cytokines as therapeutics.

Implication of 99mTc-sum IL-2 SPECT/CT in immunotherapy by imaging of tumor-infiltrating T cells

BACKGROUND

Although immune checkpoint blockade (ICB) and adoptive T cell transfer (ACT) therapy have achieved impressive clinical outcomes, majority of patients do not respond to immunotherapy. Tumor-infiltrating T cells, a critical factor to immunotherapy, is dynamically changing. Therefore, a reliable real-time in vivo imaging system for tumor-infiltrating T cells, but not immunohistochemical analyses, will be more valuable to predict response and guide immunotherapy. In this study, we developed a new SPECT/CT imaging probe ^99mTc-sum IL-2 targeting the IL-2Rβ/IL-2Rγ (CD122/CD132) receptor on tumor-infiltrating T cells, and evaluated its application in predicting the immune response to anti-PD-L1 (αPD-L1) therapy as well as tracking infused T cells in ACT therapy.

METHODS

The binding affinity of the super mutated IL-2 (sum IL-2) in various T cell subtypes was measured. Sum IL-2 was subsequently labeled with ^99mTc through Sortase-A mediated site-specific transpeptidation. SPECT/CT imaging and biodistribution studies of ^99mTc-sum IL-2 were performed in a MC38 mouse model. Wild type IL-2 (IL-2) was used as control in the above studies. Finally, we evaluated ^99mTc-sum IL-2 SPECT/CT for the detection of tumor-infiltrating T cells in the context of αPD-L1 immunotherapy and ACT therapy.

RESULTS

Sum IL-2 preferentially bound to CD8⁺ T cells, especially activated CD8⁺ T cells, while IL-2 showed biased binding to Treg cells. As a result, ^99mTc-sum IL-2 could detect tumor-infiltrating T cells. In the MC38 tumor model, SPECT/CT imaging showed the increased tumor uptake of ^99mTc-sum IL-2 after αPD-L1 treatment, suggesting that the treatment significantly increased tumor-infiltrating T cells, resulting in a correspondingly significant curative effect. In addition, ^99mTc-sum IL-2 SPECT/CT could also track the infiltration of antigen-specific cytotoxic CD8⁺ T cells during ACT therapy.

CONCLUSION

^99mTc-sum IL-2 has great clinical potential for non-invasive and specific SPECT/CT imaging of tumor-infiltrating T cells as well as for timely prediction and evaluation of the therapeutic efficacy of ICB and ACT therapy.

Bispecific PD1-IL2v and anti-PD-L1 break tumor immunity resistance by enhancing stem-like tumor-reactive CD8+ T cells and reprogramming macrophages

Immunotherapies have shown remarkable, albeit tumor-selective, therapeutic benefits in the clinic. Most patients respond transiently at best, highlighting the importance of understanding mechanisms underlying resistance. Herein, we evaluated the effects of the engineered immunocytokine PD1-IL2v in a mouse model of de novo pancreatic neuroendocrine cancer that is resistant to checkpoint and other immunotherapies. PD1-IL2v utilizes anti-PD-1 as a targeting moiety fused to an immuno-stimulatory IL-2 cytokine variant (IL2v) to precisely deliver IL2v to PD-1⁺ T cells in the tumor microenvironment. PD1-IL2v elicited substantial infiltration by stem-like CD8⁺ T cells, resulting in tumor regression and enhanced survival in mice. Combining anti-PD-L1 with PD1-IL2v sustained the response phase, improving therapeutic efficacy both by reprogramming immunosuppressive tumor-associated macrophages and enhancing T cell receptor (TCR) immune repertoire diversity. These data provide a rationale for clinical trials to evaluate the combination therapy of PD1-IL2v and anti-PD-L1, particularly in immunotherapy-resistant tumors infiltrated with PD-1⁺ stem-like T cells.

Targeting Ibrutinib to Tumor-Infiltrating T Cells with a Sialic Acid Conjugate-Modified Phospholipid Complex for Improved Tumor Immunotherapy

Immune checkpoint blockade (ICB) treatment for the clinical therapy of numerous malignancies has attracted widespread attention in recent years. Despite being a promising treatment option, developing complementary strategies to enhance the proportion of patients benefiting from ICB therapy remains a formidable challenge because of the complexity of the tumor microenvironment. Ibrutinib (IBR), a covalent inhibitor of Bruton's tyrosine kinase (BTK), has been approved as a clinical therapy for numerous B-cell malignancies. IBR also irreversibly inhibits interleukin-2 inducible T cell kinase (ITK), an essential enzyme in Th2-polarized T cells that participates in tumor immunosuppression. Ablation of ITK by IBR can elicit Th1-dominant antitumor immune responses and potentially enhance the efficacy of ICB therapy in solid tumors. However, its poor solubility and rapid clearance in vivo restrict T cell targetability and tumor accumulation by IBR. A sialic acid derivative-modified nanocomplex (SA-GA-OCT@PC) has been reported to improve the efficacy of IBR-mediated combination immunotherapy in solid tumors. In vitro and in vivo experiments showed that SA-GA-OCT@PC effectively accumulated in tumor-infiltrating T cells mediated by Siglec-E and induced Th1-dominant antitumor immune responses. SA-GA-OCT@PC-mediated combination therapy with PD-L1 blockade agents dramatically suppressed tumor growth and inhibited tumor relapse in B16F10 melanoma mouse models. Overall, the combination of the SA-modified nanocomplex platform and PD-L1 blockade offers a treatment opportunity for IBR in solid tumors, providing novel insights for tumor immunotherapy.

Adoptive Cellular Therapy for Metastatic Melanoma: The Road to Commercialization and Treatment Guidelines for Clinicians

Adoptive cell therapy (ACT) using tumor-infiltrating lymphocytes (TILs) has been gaining promise as a therapeutic option for metastatic melanoma. By harnessing the power of patients' tumor-resident lymphocytes, TIL therapy has shown promise in delivering durable, complete responses for patients who have progressed with other treatments, including checkpoint inhibition. This form of personalized medicine has traditionally been limited to select academic facilities with the infrastructure and resources to generate TIL cells and care for patients during the treatment phase. In this review, the authors discuss the role of TIL therapy for patients with metastatic melanoma, including the current state of therapeutic options, logistics of TIL harvest and infusion, management of infusion-specific toxicities, and foundational steps for surgeons and oncologists to establish cell-based therapies in individual hospitals and cancer centers.

Engineered antibody cytokine chimera synergizes with DNA-launched nanoparticle vaccines to potentiate melanoma suppression in vivo

Cancer immunotherapy has demonstrated great promise with several checkpoint inhibitors being approved as the first-line therapy for some types of cancer, and new engineered cytokines such as Neo2/15 now being evaluated in many studies. In this work, we designed antibody-cytokine chimera (ACC) scaffolding cytokine mimetics on a full-length tumor-specific antibody. We characterized the pharmacokinetic (PK) and pharmacodynamic (PD) properties of first-generation ACC TA99-Neo2/15, which synergized with DLnano-vaccines to suppress in vivo melanoma proliferation and induced significant systemic cytokine activation. A novel second-generation ACC TA99-HL2-KOA1, with retained IL-2Rβ/γ binding and attenuated but preserved IL-2Rα binding, induced lower systemic cytokine activation with non-inferior protection in murine tumor studies. Transcriptomic analyses demonstrated an upregulation of Type I interferon responsive genes, particularly ISG15, in dendritic cells, macrophages and monocytes following TA99-HL2-KOA1 treatment. Characterization of additional ACCs in combination with cancer vaccines will likely be an important area of research for treating melanoma and other types of cancer.

Synthetic cytokine circuits that drive T cells into immune-excluded tumors

Chimeric antigen receptor (CAR) T cells are ineffective against solid tumors with immunosuppressive microenvironments. To overcome suppression, we engineered circuits in which tumor-specific synNotch receptors locally induce production of the cytokine IL-2. These circuits potently enhance CAR T cell infiltration and clearance of immune-excluded tumors, without systemic toxicity. The most effective IL-2 induction circuit acts in an autocrine and T cell receptor (TCR)- or CAR-independent manner, bypassing suppression mechanisms including consumption of IL-2 or inhibition of TCR signaling. These engineered cells establish a foothold in the target tumors, with synthetic Notch-induced IL-2 production enabling initiation of CAR-mediated T cell expansion and cell killing. Thus, it is possible to reconstitute synthetic T cell circuits that activate the outputs ultimately required for an antitumor response, but in a manner that evades key points of tumor suppression.

Potent immunomodulatory and antitumor effect of anti-CD20-IL2no-alpha tri-functional immunocytokine for cancer therapy

Introduction

The anti-CD20 antibody rituximab (RTX) has substantially improved outcomes of patients with B-cell lymphomas, although more efficient therapies are needed for refractory or relapsing lymphomas. An approach to increase the clinical effectiveness of anti-tumor therapy is the use of antibody-cytokine fusion proteins (immunocytokines (ICKs)) to deliver at the tumor site the antibody effector functions and cytokines that trigger anti-tumor activities. In particular, IL-2-based ICKs have shown significant results in preclinical studies but not in clinical trials due to the toxicity profile associated to high doses IL-2 and the undesired expansion of Tregs.

Methods

To improve the efficacy of RTX therapy, we fused a murine (mIgG2a) or a human (hIgG1) version of RTX to a mutated IL-2 (no-alpha mutein), which has a disrupted affinity for the high affinity IL-2 receptor (IL-2R) to prevent the stimulation of Tregs and reduce the binding to endothelial cells expressing CD25, the α chain of high affinity IL-2R. Characterization of anti-CD20-IL2no-alpha ICKs was performed by SDS-PAGE, Western-blotting and SEC-HPLC and also by several functional in vitro techniques like T-cell proliferation assays, apoptosis, CDC and ADCC assays. The in vivo activity was assessed by using murine tumor cells expressing huCD20 in C57/Bl6 mice.

Results

Both ICKs exhibited similar in vitro specific activity of their IL2no-alpha mutein moieties and kept CD20-binding capacity. Anti-CD20-IL2no-alpha (hIgG1) retained antibody effector functions as complement-dependent cytotoxicity and enhanced direct apoptosis, NK cell activation and antibody-dependent cellular cytotoxicity relative to RTX. In addition, both ICKs demonstrated a higher antitumor efficacy than parental molecules or their combination in an EL4-huCD20 tumor model in immunocompetent mice. Anti-CD20-IL2no-alpha (hIgG1) strongly expanded NK and CD8+ T cells but not Tregs in tumor-bearing mice.

Discussion

These findings suggest that anti-CD20-IL2no-alpha could represent an alternative treatment for B cell lymphoma patients, mainly those refractory to RTX therapy.

Therapeutic antibodies for precise cancer immunotherapy: current and future perspectives

Antibodies, as one of the most important components of host adaptive immune system, play an important role in defense of infectious disease, immune surveillance, and autoimmune disease. Due to the development of recombinant antibody technology, antibody therapeutics become the largest and rapidly expanding drug to provide major health benefits to patients, especially for the treatment of cancer patients. Many antibody-based therapeutic strategies have been developed including monoclonal antibodies, antibody-drug conjugates, bispecific and trispecific antibodies and pro-antibodies with promising results from both clinical and pre-clinical trials. However, the response rate and side-effect still vary between patients with undefined mechanisms. Here, we summarized the current and future perspectives of antibody-based cancer immunotherapeutic strategies for designing next-generation drugs.

IL-2 delivery by engineered mesenchymal stem cells re-invigorates CD8+ T cells to overcome immunotherapy resistance in cancer

Immune checkpoint blockade (ICB)-based immunotherapy depends on functional tumour-infiltrating lymphocytes (TILs), but essential cytokines are less understood. Here we uncover an essential role of endogenous IL-2 for ICB responsiveness and the correlation between insufficient IL-2 signalling and T-cell exhaustion as tumours progress. To determine if exogenous IL-2 in the tumour microenvironment can overcome ICB resistance, we engineered mesenchymal stem cells (MSCs) to successfully deliver IL-2 mutein dimer (SIL2-EMSC) to TILs. While MSCs have been used to suppress inflammation, SIL2-EMSCs elicit anti-tumour immunity and overcome ICB resistance without toxicity. Mechanistically, SIL2-EMSCs activate and expand pre-existing CD8⁺ TILs, sufficient for tumour control and induction of systemic anti-tumour effects. Furthermore, engineered MSCs create synergy of innate and adaptive immunity. The therapeutic benefits of SIL2-EMSCs were also observed in humanized mouse models. Overall, engineered MSCs rejuvenate CD8⁺ TILs and thus potentiate ICB and chemotherapy.