Tumor eradication by hetIL-15 locoregional therapy correlates with an induced intratumoral CD103intCD11b+ dendritic cell population

Interleukin-15Rα-Sushi-Fc Fusion Protein Co-Hitchhikes Interleukin-15 and Pheophorbide A for Cancer Photoimmunotherapy

Background: Interleukin-15 (IL-15) stimulates the proliferation of natural killer cells or T cells, which, in combination with photodynamic therapy (PDT), has emerged as an effective strategy for cancer photoimmunotherapy. Instead of direct cytokine receptor activation, IL-15 necessitates first binding to the IL-15 receptor α chain subunit (IL-15Rα), followed by trans-presentation to the IL-15 receptor β/γ chain subunit on the effector cells for pharmacologic activation. Therefore, the delivery of IL-15 remains a major challenge owing to its short half-life, its lack of targeting activity, and the limited availability of IL-15Rα. Methods: A co-hitchhiking delivery approach using recombinant IL-15 (rIL-15) and a photosensitizer, pheophorbide A (PhA), is developed for enhanced combinatorial cancer immunotherapy with PDT. A recombinant IL-15Rα-sushi-Fc fusion protein (rILR-Fc) is designed to load rIL-15 through the IL-15Rα sushi domain, which mimics its trans-presentation. Moreover, the Fc moiety of rILR-Fc can load PhA based on its high binding affinity. Results: Through self-assembly, rILR-Fc/PhA/rIL-15 nanoparticles (NPs) are formulated to co-hitchhike PhA and rIL-15, which improves the tumor accumulation of PhA and rIL-15 through receptor-mediated transcytosis. Moreover, the nanoparticles prolong the blood half-life of rIL-15 but do not alter the elimination rate of PhA from the blood. The rILR-Fc/PhA/rIL-15 NPs effectively elicit potent systemic antitumor immunity and long-lasting immune memory against tumor rechallenge in model mice bearing orthotopic colon tumors. Conclusions: The enhanced antitumor therapeutic effect demonstrates that the co-hitchhiking delivery strategy, optimizing the pharmacokinetics of both the photosensitizer and IL-15, provides a promising strategy for combinatorial photodynamic and IL-15 immunotherapy.

The dichotomic role of cytokines in aging

The chronic inflammation present in aged individuals is generally depicted as a detrimental player for longevity. Here, it is discussed several beneficial effects associated with the cytokines that are chronically elevated in inflammaging. These cytokines, such as IL-1β, type I interferons, IL-6 and TNF positively regulate macroautophagy, mitochondrial function, anti-tumor immune responses and skeletal muscle biogenesis, possibly contributing to longevity. On the other side, the detrimental and antagonistic role of these cytokines including the induction of sarcopenia, tissue damage and promotion of tumorigenesis are also discussed, underscoring the dichotomy associated with inflammaging and its players. In addition, it is discussed the role of the anti-inflammatory cytokine IL-10 and other cytokines that affect aging in a more linear way, such as IL-11, which promotes senescence, and IL-4 and IL-15, which promotes longevity. It is also discussed more specific regulators of aging that are downstream cytokines-mediated signaling.

Leveraging long-acting IL-15 agonists for intratumoral delivery and enhanced antimetastatic activity

Introduction

IL-15 agonists hold promise as immunotherapeutics due to their ability to induce the proliferation and expansion of cytotoxic immune cells including natural killer (NK) and CD8+ T cells. However, they generally have short half-lives that necessitate frequent administration to achieve efficacy. To address this limitation, we have developed a half-life extension technology using hydrogel microspheres (MS). Here, the therapeutic is tethered to MSs by a releasable linker with pre-programed cleavage rates. We previously showed the MS conjugate of single-chain IL-15, MS~IL-15, effectively increased the half-life of IL-15 to approximately 1 week and enhanced the pharmacodynamics. We sought to determine whether the same would be true with a MS conjugate of the IL-15 agonist, receptor-linker IL-15 (RLI).

Methods

We prepared a long acting MS conjugate of RLI, MS~RLI. The pharmacokinetics and pharmacodynamics of MS~RLI were measured in C57BL/6J mice and compared to MS~IL-15. The antitumor efficacy of MS~RLI was measured when delivered subcutaneously or intratumorally in the CT26 tumor model and intratumorally in the orthotopic EO771 tumor model.

Results

MS~RLI exhibited a half-life of 30 h, longer than most IL-15 agonists but shorter than MS~IL-15. The shorter than expected half-life of MS~RLI was shown to be due to target-mediated-disposition caused by an IL-15 induced cytokine sink. MS~RLI resulted in very potent stimulation of NK and CD44hiCD8+ T cells, but also caused significant injection-site toxicity that may preclude subcutaneous administration. We thus pivoted our efforts toward studying the MS~RLI for long-acting intra-tumoral therapy, where some degree of necrosis might be beneficial. When delivered intra- tumorally, both MS~IL-15 and MS~RLI had modest anti-tumor efficacy, but high anti- metastatic activity.

Conclusion

Intra-tumoral MS~RLI and MS~RLI combined with systemic treatment with other agents could provide beneficial antitumor and anti-metastatic effects without the toxic effects of systemic IL-15 agonists. Our findings demonstrate that intra-tumorally administered long-acting IL-15 agonists counter two criticisms of loco-regional therapy: the necessity for frequent injections and the challenge of managing metastases.

Enhancing Therapeutic Efficacy of FLT3 Inhibitors with Combination Therapy for Treatment of Acute Myeloid Leukemia

FMS-like tyrosine kinase 3 (FLT3) mutations are genetic changes found in approximately thirty percent of patients with acute myeloid leukemia (AML). FLT3 mutations in AML represent a challenging clinical scenario characterized by a high rate of relapse, even after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The advent of FLT3 tyrosine kinase inhibitors (TKIs), such as midostaurin and gilteritinib, has shown promise in achieving complete remission. However, a substantial proportion of patients still experience relapse following TKI treatment, necessitating innovative therapeutic strategies. This review critically addresses the current landscape of TKI treatments for FLT3+ AML, with a particular focus on gilteritinib. Gilteritinib, a highly selective FLT3 inhibitor, has demonstrated efficacy in targeting the mutant FLT3 receptor, thereby inhibiting aberrant signaling pathways that drive leukemic proliferation. However, monotherapy with TKIs may not be sufficient to eradicate AML blasts. Specifically, we provide evidence for integrating gilteritinib with mammalian targets of rapamycin (mTOR) inhibitors and interleukin-15 (IL-15) complexes. The combination of gilteritinib, mTOR inhibitors, and IL-15 complexes presents a compelling strategy to enhance the eradication of AML blasts and enhance NK cell killing, offering a potential for improved patient outcomes.

Resident memory T cells and cancer

Tissue-resident memory T (TRM) cells positively correlate with cancer survival, but the anti-tumor mechanisms underlying this relationship are not understood. This review reconciles these observations, summarizing concepts of T cell immunosurveillance, fundamental TRM cell biology, and clinical observations on the role of TRM cells in cancer and immunotherapy outcomes. We also discuss emerging strategies that utilize TRM-phenotype cells for patient diagnostics, staging, and therapy. Current challenges are highlighted, including a lack of standardized T cell nomenclature and our limited understanding of relationships between T cell markers and underlying tumor biology. Existing findings are integrated into a summary of the field while emphasizing opportunities for future research.

First-in-human phase I/Ib study of NIZ985, a recombinant heterodimer of IL-15 and IL-15Rα, as a single agent and in combination with spartalizumab in patients with advanced and metastatic solid tumors

BACKGROUND

Preclinically, interleukin-15 (IL-15) monotherapy promotes antitumor immune responses, which are enhanced when IL-15 is used in combination with immune checkpoint inhibitors (ICIs). This first-in-human study investigated NIZ985, a recombinant heterodimer comprising physiologically active IL-15 and IL-15 receptor α, as monotherapy and in combination with spartalizumab, an anti-programmed cell death protein-1 (anti-PD-1) monoclonal antibody, in patients with advanced solid tumors.

METHODS

This phase I/Ib study had two dose-escalation arms: single-agent NIZ985 administered subcutaneously thrice weekly (TIW, 2 weeks on/2 weeks off) or once weekly (QW, 3 weeks on/1 week off), and NIZ985 TIW or QW administered subcutaneously plus spartalizumab (400 mg intravenously every 4 weeks (Q4W)). The dose-expansion phase investigated NIZ985 1 µg/kg TIW/spartalizumab 400 mg Q4W in patients with anti-PD-1-sensitive or anti-PD-1-resistant tumor types stratified according to approved indications. The primary objectives were the safety, tolerability, and the maximum tolerated doses (MTDs) and/or recommended dose for expansion (RDE) of NIZ985 for the dose-expansion phase.

RESULTS

As of February 17, 2020, 83 patients (median age: 63 years; range: 28-85) were treated in dose escalation (N=47; single-agent NIZ985: n=27; NIZ985/spartalizumab n=20) and dose expansion (N=36). No dose-limiting toxicities occurred nor was the MTD identified. The most common treatment-related adverse event (TRAE) was injection site reaction (primarily grades 1-2; single-agent NIZ985: 85% (23/27)); NIZ985/spartalizumab: 89% [50/56]). The most common grade 3-4 TRAE was decreased lymphocyte count (single-agent NIZ985: 7% [2/27]; NIZ985/spartalizumab: 5% [3/56]). The best overall response was stable disease in the single-agent arm (30% (8/27)) and partial response in the NIZ985/spartalizumab arm (5% [3/56]; melanoma, pancreatic cancer, gastric cancer). In dose expansion, the disease control rate was 45% (5/11) in the anti-PD-1-sensitive and 20% (5/25) in the anti-PD-1-resistant tumor type cohorts. Pharmacokinetic parameters were similar across arms. The transient increase in CD8+ T cell and natural killer cell proliferation and induction of several cytokines occurred in response to the single-agent and combination treatments.

CONCLUSIONS

NIZ985 was well tolerated in the single-agent and NIZ985/spartalizumab regimens. The RDE was established at 1 µg/kg TIW. Antitumor activity of the combination was observed against tumor types known to have a poor response to ICIs.

TRIAL REGISTRATION NUMBER

NCT02452268.