Harnessing CD8 T cell responses using PD-1-IL-2 combination therapy

Current landscape and future prospects of interleukin-2 receptor (IL-2R) agonists in cancer immunotherapy

Immune checkpoint blockade (ICB) has significantly improved the survival for many patients with advanced malignancy. However, fewer than 50% of patients benefit from ICB, highlighting the need for more effective immunotherapy options. High-dose interleukin-2 (HD IL-2) immunotherapy, which is approved for patients with metastatic melanoma and renal cell carcinoma, stimulates CD8+ T cells and NK cells and can generate durable responses in a subset of patients. Moreover, HD IL-2 may have potential efficacy in patients whose disease has progressed following ICB and plays a vital role in expanding tumor-infiltrating lymphocyte (TIL) in TIL therapy. Despite its potential, the use of HD IL-2 is limited by severe toxicities such as hypotension and vascular leak syndrome. Additionally, only a few patients achieve a good outcome after HD IL-2 therapy. To address these challenges, numerous next-generation IL-2 receptor (IL-2 R) agonists have been developed to exhibit treatment effects while minimizing adverse events. This review will explore IL-2 biology, the clinical application of HD IL-2 therapy, and the development of novel IL-2 R agonists for cancer immunotherapy.

Targeting BATF2-RGS2 axis reduces T-cell exhaustion and restores anti-tumor immunity

OBJECTIVE

This study aims to investigate the role of RGS2 in immune regulation in lung cancer (LC) and explore the regulatory relationship between RGS2 and BATF2 in modulating T cell exhaustion and tumor immune evasion.

METHODS

Single-cell transcriptome-based analysis was performed to identify CD8+ T-cell profiles and regulatory factors in six LC patients receiving neoadjuvant PD-1 blockade therapy. Mouse 3LL cells or murine tumor organoid models were transplanted into wild-type, RGS2 knock-out (RGS2-/-), or BATF2 knock-out (BATF2-/-) mice to analyze the effects of RGS2 and BATF2 on tumor growth, metastasis, and immune cell infiltration. CD8+ from these mice were isolated and co-cultured with cancer cells to analyze T cell cytotoxicity in vitro. The transcriptional regulation of RGS2 by BATF2 was analyzed using luciferase reporter assays.

RESULTS

RGS2 was highly expressed in CD8+ T-exhausted (Tex) cells and was associated with pro-inflammatory pathways. High RGS2 expression predicted poor clinical outcomes and limited response to PD-1/PD-L1 blockade therapy. In RGS2-/- mice, tumor metastasis and angiogenesis were suppressed, CD8+ effector T cells were enhanced, and T cell exhaustion markers were reduced. BATF2 was identified as a key transcriptional regulator of RGS2, promoting T cell exhaustion through inhibition of CXCL13 secretion. Knockdown of BATF2 or RGS2 impaired lung cancer cell proliferation and enhanced sensitivity to NK cell-mediated cytotoxicity in vitro. In BATF2-/- mice, the populations of immune active CD8+ T cells were increased, while exhausted T cells were reduced, leading to improved anti-tumor immune responses.

CONCLUSIONS

RGS2, regulated by BATF2, plays a critical role in driving T cell exhaustion and tumor immune evasion in LC. Targeting the BATF2-RGS2 axis may enhance the effectiveness of immunotherapy by reversing T cell exhaustion and improving anti-tumor immunity.

Immunocytokines and cytokine neutralization for cancer immunotherapy

Despite deep and growing knowledge of cytokine functions, immunotherapies based on the control of these molecules have minimally impacted cancer patient management because of limited efficacy and narrow therapeutic windows. Opportunities to enhance efficacy and mitigate side effects arise from local delivery and targeting antitumor cytokines to tumor tissue via chimeric fusion with antibodies (immunocytokines). Conversely, neutralization of protumor cytokines using antibodies, cytokine traps, or receptor antagonists offer the opportunity to increase the efficacy of conventional immunotherapy with checkpoint inhibitors while reducing their side effects. Exploiting the immunobiology of interleukin (IL)-2, IL-12, IL-15, IL-18, and IL-21 in synergistic combinations with other treatments holds promise. The antagonistic neutralization of transforming growth factor-β, tumor necrosis factor, IL-1, IL-6, and CXCR1/2 chemokines and growth differentiation factor 15 also seems to be very convenient, again as part of combination strategies.

Intrathecal nivolumab and IL-2 for treatment of leptomeningeal metastases in EGFR-mutated lung adenocarcinoma

OBJECTIVES

Leptomeningeal metastasis (LM) is a serious complication of advanced non-small-cell lung cancer (NSCLC). Intrathecal administration of nivolumab or interleukin-2 (IL-2) has demonstrated efficacy in this setting. Preclinical and limited clinical evidence suggest that combining IL-2 with anti-PD1 therapy may synergistically enhance anti-tumor immunity. However, clinical data on the efficacy and safety of intrathecal co-administration of nivolumab and IL-2 are lacking.

MATERIALS AND METHODS

We describe a case of NSCLC with LM, refractory to multiple EGFR tyrosine kinase inhibitors and previous intrathecal therapies, treated with intrathecal nivolumab and IL-2. Single-cell RNA sequencing (scRNA-seq) was performed on cerebrospinal fluid (CSF) samples collected before and after treatment.

RESULTS

This is the first reported case of intrathecal nivolumab plus IL-2 in NSCLC with LM resistant to standard systemic and intrathecal therapies. The patient experienced marked clinical improvement, including substantial remission of intracranial metastases, neurological symptom relief, and a reduction in tumor marker levels, without notable treatment-related adverse events. scRNA-seq analysis of CSF revealed a post-treatment decrease in malignant cell populations and a concomitant increase in immune effector cells, particularly CD8+ T cells and NK cells. Malignant cells exhibited upregulated antigen presentation and apoptosis. Cell-cell interaction analysis indicated enhanced NK cell-mediated cytotoxicity via FASL-FAS signaling and reduced immunosuppressive interactions between regulatory CD4+ T cells and effector memory CD8+ T cells.

CONCLUSIONS

This case report provides preliminary evidence supporting the feasibility, safety, and potential efficacy of intrathecal nivolumab and IL-2 in treating NSCLC-associated LM. These findings warrant further investigation in prospective clinical studies.

Acasunlimab, an Fc-inert PD-L1×4-1BB bispecific antibody, combined with PD-1 blockade potentiates antitumor immunity via complementary immune modulatory effects

BACKGROUND

Next-generation cancer immunotherapies aim to improve patient outcomes by combining inhibitory signal blockade with targeted T-cell costimulation in tumor and lymphoid tissues. Acasunlimab (DuoBody-PD-L1×4-1BB) is an investigational, bispecific antibody designed to elicit an antitumor immune response via conditional 4-1BB activation strictly dependent on simultaneous programmed death-ligand 1 (PD-L1) binding. Since 4-1BB is coexpressed with programmed cell death protein-1 (PD-1) on CD8+ T cells, PD-1 blockade and simultaneous costimulation through 4-1BB may synergistically enhance T-cell effector functions. We hypothesized that combining acasunlimab with PD-1 blockade to fully disrupt PD-1 interactions with both PD-L1 and PD-L2 would amplify the depth and duration of antitumor immunity.

METHODS

The effect of acasunlimab and pembrolizumab combination was analyzed in vitro using functional immune cell assays, including mixed-lymphocyte reactions and antigen-specific T-cell proliferation and cytotoxicity assays. The antitumor activity of the combination was tested in vivo in (1) MC38, MB49, Pan02, and B16F10 syngeneic tumor models using acasunlimab and anti-PD-1 mouse-surrogate antibodies; and (2) triple knock-in mice expressing the human targets using an acasunlimab chimeric antibody (chi-acasunlimab) and pembrolizumab. The mechanism of action of the combination was investigated in the MC38 syngeneic model through immunohistochemistry, flow cytometry, and bulk RNA sequencing.

RESULTS

The combination reinvigorated dysfunctional T cells in vitro, while also potentiating T-cell expansion, interleukin (IL)-2 and interferon gamma secretion and cytotoxic activity. In vivo, the combination of chi-acasunlimab and pembrolizumab or mouse-surrogate antibodies potentiated antitumor activity and survival in the humanized knock-in and multiple syngeneic mouse models, leading to durable complete tumor regressions in the MC38 model consistent with therapeutic synergy. Mechanistically, the combination enhanced clonal expansion of tumor-specific CD8+ T cells in tumor-draining lymph nodes and increased the density of proliferating and cytotoxic CD8+ T cells in the tumor microenvironment. It also potentiated the IL-2 signaling pathway, increasing the proportion of granzyme B (GZMB+) stem-like CD8+ T cells thought to have superior effector function.

CONCLUSION

These preclinical results demonstrate that conditional 4-1BB stimulation combined with complete PD-1 blockade enhances antitumor immunity through complementary mechanisms. The acasunlimab and pembrolizumab combination is being evaluated in Phase 2 (NCT05117242) and pivotal Phase 3 (NCT06635824) trials in patients with metastatic non-small cell lung cancer after checkpoint inhibitor therapy failure.

Engineering cytokines for tumor-targeting and selective T cell activation

Cytokines are promising therapeutic agents for cancer due to their immune-stimulating properties. However, their clinical application is limited by a narrow therapeutic window and dose-limiting on-target, off-tumor toxicity. Advances in protein engineering enable the selective delivery of cytokines to the tumor microenvironment (TME) and antigen-specific T cells, enhancing antitumor efficacy while reducing systemic side effects. This review focuses on selected cytokines and outlines their developmental trajectory for treating solid tumors. We highlight strategies for constructing cis-signaling immunocytokines and procytokines for precise delivery to tumor sites and discuss the biological mechanisms through which these cytokines reactivate antitumor immunity. We also discuss the challenges and future directions for creating more effective cytokine-based therapeutics.

Molecular Mechanisms Governing CD8 T Cell Differentiation and Checkpoint Inhibitor Response in Cancer

CD8 T cells play a critical role in antitumor immunity. However, over time, they often become dysfunctional or exhausted and ultimately fail to control tumor growth. To effectively harness CD8 T cells for cancer immunotherapy, a detailed understanding of the mechanisms that govern their differentiation and function is crucial. This review summarizes our current knowledge of the molecular pathways that regulate CD8 T cell heterogeneity and function in chronic infection and cancer and outlines how T cells respond to therapeutic checkpoint blockade. We explore how T cell-intrinsic and -extrinsic factors influence CD8 T cell differentiation, fate choices, and functional states and ultimately dictate their response to therapy. Identifying cells that orchestrate long-term antitumor immunity and understanding the mechanisms that govern their development and persistence are critical steps toward improving cancer immunotherapy.

circCCNY enhances lenvatinib sensitivity and suppresses immune evasion in hepatocellular carcinoma by serving as a scaffold for SMURF1 mediated HSP60 degradation

Lenvatinib is the standard first-line therapy for advanced hepatocellular carcinoma (HCC), but drug resistance significantly hampers its efficacy. Increasing evidence has shown that circular RNAs (circRNAs) play critical roles in HCC pathogenesis. However, the underlying mechanisms of lenvatinib sensitivity regulated by circRNAs remain largely unclear. The present study aims to identify circRNAs involved in lenvatinib resistance, as well as to elucidate the underlying mechanisms. High-throughput sequencing revealed that hsa_circ_0000235 (circCCNY) was downregulated in matched HCC tumor tissues and lenvatinib-resistant cells. Both in vitro and in vivo experiments revealed that downregulation of circCCNY could induce lenvatinib resistance in HCC cells. Subsequently, RNA pull-down, mass spectrometry, and RNA immunoprecipitation techniques were employed to investigate the interactions between circCCNY, HSP60, and the E3 ubiquitin ligase SMURF1. Briefly, circCCNY bounds to HSP60, subsequently leading to HSP60 ubiquitination and degradation through its interaction with the E3 ubiquitin ligase SMURF1. As a result, HSP60 degradation released Raf kinase inhibitor protein (RKIP), leading to the inactivation of the MAPK signaling pathway, and subsequently enhanced the anti-tumor effect of lenvatinib against HCC. Moreover, we also demonstrated that circCCNY could enhance CD8+ T-cell infiltration and suppress immune evasion through inhibiting the MAPK/c-Myc/PD-L1 signaling pathway. Our findings revealed that circCCNY enhances HCC sensitivity to lenvatinib and suppresses immune evasion by inhibiting the MAPK signaling pathway in HCC. This suggests that circCCNY could serve as a promising therapeutic target in HCC treatment and a potential biomarker for predicting HCC sensitivity to lenvatinib.

Peripheral blood PD-1+ T lymphocytes as biomarkers in liquid biopsies for solid tumors: Clinical significance and prognostic applications

A shift toward a T cell exhaustion phenotype is associated with the upregulation of expression of programmed cell death protein 1 (PD-1) on T lymphocytes in patients with malignant solid tumors. The interaction between PD-1 and programmed death-ligand 1 (PD-L1) inhibits PD-1+ T lymphocyte function, impacting their anti-tumor immune activity. Immune checkpoint inhibitors targeting PD-1/PD-L1 have revolutionized the treatment of various solid malignancies, improving therapeutic efficacy and survival outcomes. Peripheral blood analysis of liquid biopsies is being increasingly used to identify populations most likely to benefit from various treatment modalities. PD-1+ T lymphocytes represent the primary cell population responsive to immunotherapeutic interventions for patients with solid malignancies, as evidenced by the altered PD-1 expression levels and proportion of cells comprising the overall population of immunocytes. PD-1+ T cells in peripheral blood exert an associative and reciprocal predictive effect on homologous intratumoral cells. Distinct subpopulations of PD-1+ T cells exhibit differential ability to proliferate in the periphery and can be characterized by tumor antigen-specific and exhaustion phenotypes. These characteristics have prognostic implications, aiding in the prediction of the efficacy of antitumor therapy and predicting survival outcomes. We highlight distinct subpopulations of PD-1+ T cells, their exhaustion and antigen-specific phenotypes, and their dynamic changes over treatment, providing insights into their utility for tailoring personalized therapies. For the first time, this review discusses the role of peripheral PD-1+ T lymphocytes as prognostic biomarkers in liquid biopsies, focusing on their clinical significance, predictive value during therapy, and future research directions.

Efficacy of Anti-Cancer Immune Responses Elicited Using Tumor-Targeted IL-2 Cytokine and Its Derivatives in Combined Preclinical Therapies

Effective cancer therapies must address the tumor microenvironment (TME), a complex network of tumor cells and stromal components, including endothelial, immune, and mesenchymal cells. Durable outcomes require targeting both tumor cells and the TME while minimizing systemic toxicity. Interleukin-2 (IL-2)-based therapies have shown efficacy in cancers such as metastatic melanoma and renal cell carcinoma but are limited by severe side effects. Innovative IL-2-based immunotherapeutic approaches include immunotoxins, such as antibody-drug conjugates, immunocytokines, and antibody-cytokine fusion proteins that enhance tumor-specific delivery. These strategies activate cytotoxic CD8+ T lymphocytes and natural killer (NK) cells, eliciting a potent Th1-mediated anti-tumor response. Modified IL-2 variants with reduced Treg cell activity further improve specificity and reduce immunosuppression. Additionally, IL-2 conjugates with peptides or anti-angiogenic agents offer improved therapeutic profiles. Combining IL-2-based therapies with immune checkpoint inhibitors (ICIs), anti-angiogenic agents, or radiotherapy has demonstrated synergistic potential. Preclinical and clinical studies highlight reduced toxicity and enhanced anti-tumor efficacy, overcoming TME-driven immune suppression. These approaches mitigate the limitations of high-dose soluble IL-2 therapy, promoting immune activation and minimizing adverse effects. This review critically explores advances in IL-2-based therapies, focusing on immunotoxins, immunocytokines, and IL-2 derivatives. Emphasis is placed on their role in combination strategies, showcasing their potential to target the TME and improve clinical outcomes effectively. Also, the use of IL-2 immunocytokines in "in situ" vaccination to relieve the immunosuppression of the TME is discussed.

Dendritic cell-based biomimetic nanoparticles for foot-and-mouth disease induce robust cellular immunity

Foot-and-mouth disease (FMD) is a highly contagious and economically devastating viral disease of ruminants and swine, badly affecting the livestock industry worldwide. In clinical practice, vaccination is a frequently employed strategy to prevent foot-and-mouth disease (FMDV). However, commercial inactivated vaccines for FMD mainly rely on humoral immunity, exhibiting poor cellular immune responses and causing adverse reactions. Here, we use the double emulsion method to prepare poly (lactic-co-glycolic acid) nanoparticles (PLGA-NP) encapsulated with IL-2 cytokines, wrap the dendritic cell (DC) membrane carrying FMDV antigen information on the surface of the nanoparticles, obtaining a biomimetic nanoparticle vaccine Biom@DC with uniform size. This vaccine can effortlessly move through lymph nodes due to its nanoscale size advantage. It also possesses DC ability to present antigens, and antigen presentation can be made more effective with high biocompatibility. The sustained release of IL-2 encapsulated in the core of PLGA-NP in vivo can effectively promote the body's cellular immune response. Immune tests on mice have shown that Biom@DC may greatly increase T cell activation and proliferation both in vivo and in vitro, while also significantly reducing the fraction of inhibitory Treg cells. Furthermore, in the micro serum neutralization assay for FMDV, it has been demonstrated that the group vaccinated with Biom@DC exhibits a clear neutralizing effect. Given its strong immunogenicity, Biom@DC has the potential to develop into a novel, potent anti-FMDV vaccination.

Cold and hot tumors: from molecular mechanisms to targeted therapy

Immunotherapy has made significant strides in cancer treatment, particularly through immune checkpoint blockade (ICB), which has shown notable clinical benefits across various tumor types. Despite the transformative impact of ICB treatment in cancer therapy, only a minority of patients exhibit a positive response to it. In patients with solid tumors, those who respond well to ICB treatment typically demonstrate an active immune profile referred to as the "hot" (immune-inflamed) phenotype. On the other hand, non-responsive patients may exhibit a distinct "cold" (immune-desert) phenotype, differing from the features of "hot" tumors. Additionally, there is a more nuanced "excluded" immune phenotype, positioned between the "cold" and "hot" categories, known as the immune "excluded" type. Effective differentiation between "cold" and "hot" tumors, and understanding tumor intrinsic factors, immune characteristics, TME, and external factors are critical for predicting tumor response and treatment results. It is widely accepted that ICB therapy exerts a more profound effect on "hot" tumors, with limited efficacy against "cold" or "altered" tumors, necessitating combinations with other therapeutic modalities to enhance immune cell infiltration into tumor tissue and convert "cold" or "altered" tumors into "hot" ones. Therefore, aligning with the traits of "cold" and "hot" tumors, this review systematically delineates the respective immune characteristics, influencing factors, and extensively discusses varied treatment approaches and drug targets based on "cold" and "hot" tumors to assess clinical efficacy.

Programmed death receptor (PD-)1/PD-ligand (L)1 in urological cancers : the "all-around warrior" in immunotherapy

Programmed death receptor-1 (PD-1) and its ligand, programmed death ligand-1 (PD-L1) are essential molecules that are key in modulating immune responses. PD-L1 is constitutively expressed on various immune cells, epithelial cells, and cancer cells, where it functions as a co-stimulatory molecule capable of impairing T-cell mediated immune responses. Upon binding to PD-1 on activated T-cells, the PD-1/PD-L1 interaction triggers signaling pathways that can induce T-cell apoptosis or anergy, thereby facilitating the immune escape of tumors. In urological cancers, including bladder cancer (BCa), renal cell carcinoma (RCC), and prostate cancer (PCa), the upregulation of PD-L1 has been demonstrated. It is linked to poor prognosis and enhanced tumor immune evasion. Recent studies have highlighted the significant role of the PD-1/PD-L1 axis in the immune escape mechanisms of urological cancers. The interaction between PD-L1 and PD-1 on T-cells further contributes to immunosuppression by inhibiting T-cell activation and proliferation. Clinical applications of PD-1/PD-L1 checkpoint inhibitors have shown promising efficacy in treating advanced urological cancers, significantly improving patient outcomes. However, resistance to these therapies, either intrinsic or acquired, remains a significant challenge. This review aims to provide a comprehensive overview of the role of the PD-1/PD-L1 signaling pathway in urological cancers. We summarize the regulatory mechanism underlying PD-1 and PD-L1 expression and activity, including genetic, epigenetic, post-transcriptional, and post-translational modifications. Additionally, we discuss current clinical research on PD-1/PD-L1 inhibitors, their therapeutic potential, and the challenges associated with resistance. Understanding these mechanisms is crucial for developing new strategies to overcome therapeutic limitations and enhance the efficacy of cancer immunotherapy.