Optimising IL-2 for Cancer Immunotherapy

Conditional Activation of Protein Therapeutics by Templated Removal of Peptide Nucleic Acid Masking Groups

Interleukin-2 (IL-2)-based therapeutics are emerging as treatments for immunotherapy; however, systemic activation of immune cells hampers their success. Chemically controlling the activity of potent cytokines could mitigate unwanted T cell stimulation and widen their therapeutic window. In this study, we developed a strategy for the conditional activation of proteins utilizing removable peptide nucleic acid (PNA) masking groups. Site-specific installation of "Lock"-PNAs containing a cleavage thioester linkage enabled steric blockage of receptor binding sites. Rapid unmasking and activation were performed by the addition of a complementary "Key"-PNA containing a cysteine (Cys) residue, which forms a PNA-PNA duplex leading to a proximity-accelerated cleavage step and release of the active protein. We exemplified the versatility of this methodology on de novo cytokine neoleukin-2/15 (Neo-2/15) through the preparation of PNA conjugates including homodimers, PNA-stapled conjugates, and dual PNA-bridged dimers. All constructs were effectively unmasked at low micromolar concentrations. Further, we demonstrated the conditional activation of a masked conjugate of Neo-2/15 in binding studies to the IL-2 receptors and in an ex vivo T cell signaling assay displaying a 480-fold potency increase upon activation. Finally, we extended the strategy to a designed ankyrin repeat protein (DARPin) activating the human CD40 receptor demonstrating successful masking and unmasking.

Selective activation of interleukin-2/interleukin-15 receptor signaling in tumor microenvironment using paired bispecific antibodies

BACKGROUND

Owing to their roles in promoting T cell and natural killer (NK) cell activation and proliferation, interleukins-2 (IL-2) and interleukins-15 (IL-15) have been pursued as promising pathways to target in cancer immunotherapy. Nonetheless, their wider therapeutic application has been hampered by severe dose-limiting toxicities including systemic cytokine release and organ edema for IL-2, and inconvenient intratumoral administration for IL-15. To address these safety issues, we generated IL-2R/IL-15R×TAA (tumor-associated antigen) bispecific antibody (bsAb) pairs to selectively activate IL-2R signaling in the tumor microenvironment.

METHODS

Each bsAb pair is composed of one bsAb targeting CD122 and a TAA epitope, and the other bsAb targeting CD132 and the same or a different TAA epitope. In vitro assays were performed to characterize the IL-2R/IL-15R agonistic activity of the bsAb pairs, as well as their capacity to enhance T-cell-mediated killing of TAA+ malignant cells. Using a syngeneic mouse tumor model, in vivo biological activity and systemic toxicity of the bsAb pairs were assessed in comparison with IL-2. The in vivo antitumor activity was assessed in combination with an anti-mouse programmed cell death protein 1 (mPD-1) monoclonal antibody.

RESULTS

We demonstrated with two different TAAs (human epidermal growth factor receptor 2 (HER2) and mesothelin (MSLN)) that the CD122×TAA/CD132×TAA bsAb pairs mediate effective activation of immune cells exclusively in the presence of TAA+ tumor cells. In syngeneic hMSLN-MC38 tumor-bearing mice, the CD122×MSLN-1/CD132×MSLN-2 bsAb pair promotes selective activation and expansion of NK cells and central memory CD8+ T cells inside the tumor without inducing organ edema or systemic cytokine release, two well-known manifestations of IL-2 associated toxicity. In combination with checkpoint inhibitor anti-mPD-1, the bsAb pair boosts the accumulation of CD8+ effector T cells and NK cells, leading to a favorable CD8+ T cell to CD4+ regulatory T cell ratio for a more robust inhibition of tumor growth.

CONCLUSIONS

Overall, the findings suggest that this innovative therapeutic approach effectively leverages the antitumor activity of IL-2 and IL-15 pathways while minimizing their associated systemic toxicities. This dual bsAb format holds potential for broader application in other immune-activating pathways.

The possible anti-tumor effects of regulatory T cells plasticity / IL-35 in the tumor microenvironment of the major three cancer types

T lymphocytes are among the immunological cells that make up the tumor microenvironment (TME), and they are essential in the growth of tumors and anti-tumor reactions. Regulatory T cells (Treg cells) are a subset of CD4+ T cells in the immune system that suppress the immune system. They are distinguished by their expression of the master transcription factor forkhead box protein P3 (FOXP3). Furthermore, Treg cells are essential for maintaining immunological homeostasis, inhibiting inflammation, and maintaining self-tolerance. In a variety of malignancies within the TME, Treg cells demonstrate notable flexibility and functional diversity. Highly plastic Treg cells can change into Th-like Treg cells in specific circumstances, which allow them to secrete particular pro-inflammatory cytokines. Interleukin 35 (IL-35) is a part of the immunosuppressive cytokines that belong to the IL-12 family. Treg cells release IL-35, which was elevated in the peripheral blood and TME of numerous cancer patients, implying that IL-35 in the TME may be an intriguing target for cancer therapy. In cancer, IL-35 is a two-edged sword; it promotes tumorigenicity in cancer cells while shielding them from apoptosis. Nonetheless, other investigations have mentioned its conflicting effects on cancer prevention. Herein, we provide an updated understanding of the critical mechanisms behind the anticancer immunity mediated by Treg cells plasticity, the role of IL-35, and tactics to strengthen the immune response against malignancies, outlining major clinical trials that used Treg cells/IL-35 therapies in the three main cancer types (lung, breast, and colorectal cancers).

Cryoablation plus chemotherapy regimen enhance anti-tumor immune response in a mouse model of Lewis lung cancer

BACKGROUND

Cryoablation (cryo) is a local anti-tumor method and activation of immunity is one of its mechanisms, but it is affected by many factors. Numerous studies have proved that combination therapy based on cryo can activate immunity more effectively and synergistically. Cryo combined with chemotherapy(chemo) has been proven to improve the quality of life and prolong survival of tumor patients, but the immune effect is still unclear.

METHODS

C57B/L6 mouse lung cancer subcutaneous transplanted tumor model was established and sacrificed at two time points after intervention. We observed the effects of cryo + chemo on survival time, tumor growth, and dynamic changes of immune cells and cytokines.

RESULTS

Cryo + chemo could not only significantly prolong the survival period of mice, inhibit tumor growth and reduce the proliferation activity of tumor cells, but also promote immune response more effectively. Cryo + chemo could increase the number of CD4+ T cells both in spleen and tumor microenvironment, decrease the infiltration of Treg cells in the tumor microenvironment. Besides, cryo + chemo could increase the expression levels of IL-2 and IFN-γ, and reduce the levels of TGF-β. However, it is worth noting that the immune-promoting effect gradually decreases over time.

CONCLUSIONS

Cryo + chemo can effectively inhibit the growth of lung cancer, prolong the survival period and activate the immune response, providing a theoretical basis for the combined treatment. How to maintain the immune response for a long time is the next problem to be solved.

Efficacy and safety of natural killer cell therapy in patients with solid tumors: a systematic review and meta-analysis

Introduction

In 2020, global cancer statistics reported 19.3 million new cases and 10 million deaths annually, highlighting the urgent need for effective treatments. Current therapies, such as surgery, radiation, and chemotherapy, have limitations in comprehensively addressing solid tumor. Recent advances in cancer biology and immuno-oncology, including CAR-T cell therapy, show promise but face efficacy challenges against solid tumors.

Methods

This meta-analysis systematically reviewed studies from PubMed, Embase, Cochrane, and ClinicalTrials.gov databases up to May 2024 to evaluate the clinical efficacy and safety of unmodified NK cell therapies in solid tumors. The included trials focused on reporting objective response rates (ORR).

Results

Thirty-one trials involving 600 patients across various cancers (e.g., NSCLC, HCC, breast, ovarian) were analyzed. NK cell therapies demonstrated promising ORRs, particularly 72.3% in hepatocellular carcinoma, often in combination with local therapies. Safety profiles were favorable, with fatigue being the most common adverse event.

Discussion

NK cell therapies represent a promising treatment option for solid tumors, offering a viable alternative to genetically modified cell therapies like CAR-T. Further research is needed to optimize the clinical utility of NK cell therapy and integrate it effectively into standard cancer treatment regimens.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023438410, identifier CRD42023438410.