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Background: Low-dose IL-2 (Ld-IL2) has shown favorable therapeutic effects in systemic lupus erythematosus (SLE) therapy. However, previous clinical trials reported an SLE Responder Index-4 (SRI-4) response rate of 65.52%-68%, with approximately half failing to achieve the primary endpoint by week 24. Our study aims to determine the real-world use of Ld-IL2 and to identify determinants of its effectiveness in SLE., Methods: We pooled data from 342 SLE patients undergoing sequential Ld-IL2 treatment, with 314 persisting for over 3 months were included in effectiveness and prediction analyses. All patients were categorized into responder (n = 136) and non-responder group (n = 178) according to SRI-4. Lupus Low Disease Activity State (LLDAS) was also analyzed to validate our results., Results: Rash, lower complement 3 (C3), and renal involvement including urine protein, urine occult blood and urine casts emerged as prominent predictors of achieving SRI-4. Adjusting for baseline values using the ratio of change to baseline revealed significant differences in CD4 + T cell immune profiles between responders and non-responders. ROC analysis confirmed a satisfactory performance of rash, renal involvement, percentage change of CD4 + T cells, and C3 in predicting SRI-4, yielding an AUC of 0.933. LLDAS analysis showed that hematological involvements and lower CLA + Treg were potent predictive markers in LLDAS attainment. Conversely, renal involvement failed to have significant association in achieving LLDAS. The analysis of background therapy in SLE patients showed that MMF was more likely to reach the SRI-4 response with the combination of Ld-IL2., Conclusions: These findings uncovered the predictors of Ld-IL2 treatment efficacy in SLE patients and provided guidance to physicians for rational utilization., (© 2024. The Author(s).)

The expansion of T follicular helper (Tfh) cells correlates with disease progression in human and murine systemic lupus erythematosus (SLE). Unfortunately, there are no therapies to deplete Tfh cells. Importantly, low-dose rIL-2-based immunotherapy shows potent immunosuppressive effects in SLE patients and lupus-prone mice, primarily attributed to the expansion of regulatory T cells (Tregs). However, IL-2 can also inhibit Tfh cell differentiation. In this study, we investigate the potential of low-dose rIL-2 to deplete Tfh cells and prevent autoantibody responses in SLE. Our data demonstrate that low-dose rIL-2 efficiently depletes autoreactive Tfh cells and prevents autoantibody responses in lupus-prone mice. Importantly, this immunosuppressive effect was independent of the presence of Tregs. The therapeutic potential of eliminating Tfh cells was confirmed by selectively deleting Tfh cells in lupus-prone mice. Our findings demonstrate the critical role of Tfh cells in promoting autoantibody responses and unveil, (to our knowledge), a novel Treg-independent immunosuppressive function of IL-2 in SLE., (Copyright © 2024 by The American Association of Immunologists, Inc.)

We have created a precisely pegylated IL-2 [SAR-444245 (SAR'245) or pegenzileukin, previously THOR-707] designed for proliferation of target CD8+ T and NK cells for anticancer activity, with minimal expansion of anti-target regulatory CD4+ T cells (Treg) that counter their action, or eosinophils that trigger vascular leak syndrome (VLS). We performed in vivo studies in nonhuman primates (NHP) to monitor the safety of SAR'245, pharmacokinetic profile, and pharmacodynamic parameters including expansion of peripheral CD8+ T and NK cells, and effects on Tregs and eosinophils. Studies included multiple ascending dosing and repeat dosing with different regimens (QW, Q2W, Q3W and Q4W). We also conducted ex vivo studies using human primary cells to further evaluate SAR'245 stimulation of target cells alone and in combination with programmed cell-death 1 (PD-1) checkpoint inhibitors. The pharmacokinetic profile of SAR'245 in NHP demonstrated dose-proportional exposure that was comparable with redosing. It elicited expansion of peripheral CD8+ T and NK cells that was comparable with each dose and with multiple dosing regimens. Once-weekly dosing showed no significant adverse effects, including no hallmark signs of VLS at dosing levels up to 1 mg/kg. Ex vivo, SAR'245 enhanced T-cell receptor responses alone and in combination with PD-1 inhibitors without inducing cytokines associated with cytokine release syndrome or VLS. Results support the clinical development of SAR'245 as a drug candidate for the treatment of solid tumors, alone or in combination with PD-1 inhibitory agents., Significance: SAR-444245 (SAR'245, pegenzileukin) is an extended half-life IL-2 that targets effector CD8+ T and NK cells, with little effect on regulatory T cells. We show that in the nonhuman primate model that closely approximates human immune function and response to IL-2, SAR'245 selectively activates CD8+ T and NK effectors without significant serious side effects (vascular leak syndrome or cytokine release syndrome), suggesting its potential for the treatment of solid tumors in humans., (©2024 The Authors; Published by the American Association for Cancer Research.)

Purpose: Cytokines IL2 and IL12 exhibit potent anticancer activity but suffer a narrow therapeutic window due to off-tumor immune cell activation. Engineering cytokines with the ability to bind and associate with tumor collagen after intratumoral injection potentiated response without toxicity in mice and was previously safe in pet dogs with sarcoma. Here, we sought to test the efficacy of this approach in dogs with advanced melanoma., Patients and Methods: This study examined 15 client-owned dogs with histologically or cytologically confirmed malignant melanoma that received a single 9-Gy fraction of radiotherapy, followed by six cycles of combined collagen-anchored IL2 and IL12 therapy every 2 weeks. Cytokine dosing followed a 3 + 3 dose escalation design, with the initial cytokine dose chosen from prior evaluation in canine sarcomas. No exclusion criteria for tumor stage or metastatic burden, age, weight, or neuter status were applied for this trial., Results: Median survival regardless of the tumor stage or dose level was 256 days, and 10/13 (76.9%) dogs that completed treatment had CT-measured tumor regression at the treated lesion. In dogs with metastatic disease, 8/13 (61.5%) had partial responses across their combined lesions, which is evidence of locoregional response. Profiling by NanoString of treatment-resistant dogs revealed that B2m loss was predictive of poor response to this therapy., Conclusions: Collectively, these results confirm the ability of locally administered tumor-anchored cytokines to potentiate responses at regional disease sites when combined with radiation. This evidence supports the clinical translation of this approach and highlights the utility of comparative investigation in canine cancers., (©2024 American Association for Cancer Research.)

Purpose: TILT-123 (igrelimogene litadenorepvec) is an oncolytic adenovirus armed with TNFa and IL2, designed to induce T-cell infiltration and cytotoxicity in solid tumors., Patients and Methods: TUNIMO (NCT04695327) was a single-arm, multicenter phase I dose-escalation trial designed to assess the safety of TILT-123 in advanced solid cancers refractory to standard therapy. Patients received intravenous and intratumoral TILT-123. The primary endpoint was safety by adverse events (AE), laboratory values, vital signs, and electrocardiograms. Secondary endpoints included tumor response, pharmacokinetics, and predictive biomarkers., Results: Twenty patients were enrolled, with a median age of 58 years. Most prevalent cancer types included sarcomas (35%), melanomas (15%) and ovarian cancers (15%). No dose-limiting toxicities were observed. The most frequent treatment-related AEs included fever (16.7%), chills (13.0%), and fatigue (9.3%). Ten patients were evaluable for response on day 78 with RECIST 1.1, iRECIST or PET-based evaluation. The disease control rate by PET was 6/10 (60% of evaluable patients) and 2/10 by RECIST 1.1 and iRECIST(20%of evaluable patients). Tumor size reductions occurred in both injected and non-injected lesions. TILT-123 was detected in injected and non-injected tumors, and virus was observed in blood after intravenous and intratumoral injections. Treatment resulted in reduction of lymphocytes in blood, with concurrent lymphocyte increases in tumors, findings compatible with trafficking., Conclusions: TILT-123 was safe and able to produce antitumor effects in local and distant lesions in heavily pre-treated patients. Good tolerability of TILT-123 facilitates combination studies, several of which are ongoing (NCT04217473, NCT05271318, NCT05222932, and NCT06125197). See related commentary by Silva-Pilipich and Smerdou, p. 3649., (©2024 The Authors; Published by the American Association for Cancer Research.)

Purpose: The aim of the study was to evaluate the safety/tolerability and pharmacokinetics of simlukafusp alfa (FAP-IL2v), an immunocytokine containing an anti-fibroblast activation protein-α (FAP) antibody and an IL2 variant, administered alone or with the PDL1 inhibitor atezolizumab, in Japanese patients with advanced solid tumors., Patients and Methods: In this phase 1, open-label, dose-escalation study, patients received i.v. FAP-IL2v at 10 or 15/20 mg alone or 10 mg when combined with i.v. atezolizumab. The primary objectives were identification of dose-limiting toxicities (DLT), recommended dose, and maximum tolerated dose, and evaluation of the safety/tolerability and pharmacokinetics of FAP-IL2v alone and combined with atezolizumab., Results: All 11 patients experienced adverse events (AE) during FAP-IL2v treatment. Although most AEs were of mild severity, four treatment-related AEs led to study treatment discontinuation in two patients: one with infusion-related reaction, hypotension, and capillary leak syndrome, and the other with increased aspartate aminotransferase. No AE-related deaths occurred. One DLT (grade 3 hypotension) occurred in a patient receiving FAP-IL2v 15/20 mg alone. The recommended dose and maximum tolerated dose could not be determined. The pharmacokinetics of FAP-IL2v remained similar with or without atezolizumab. The study was terminated early as FAP-IL2v development was discontinued because of portfolio prioritization (not for efficacy/safety reasons)., Conclusions: This study describes the safety/tolerability of FAP-IL2v 10 mg alone and in combination with atezolizumab in Japanese patients with advanced solid tumors; one DLT (hypotension) occurred with FAP-IL2v 15/20 mg. However, dose escalation of FAP-IL2v was not conducted because of early study termination., Significance: This phase I study assessed the safety/tolerability and PK of simlukafusp alfa alone or combined with atezolizumab in Japanese patients with advanced solid tumors. No notable differences in PK were noted with the combination versus simlukafusp alfa alone; however, high-dose simlukafusp alfa treatment was associated with recombinant IL2-related toxicity, despite the drug's FAP targeting and IL2Rβγ-biased IL2 variant design., (©2024 The Authors; Published by the American Association for Cancer Research.)

Purpose: Bempegaldesleukin (BEMPEG) is a pegylated interleukin (IL)-2 cytokine prodrug engineered to provide controlled and sustained activation of the clinically validated IL-2 pathway, with the goal of preferentially activating and expanding effector CD8 + T cells and natural killer cells over immunosuppressive regulator T cells in the tumor microenvironment. The open-label, phase III randomized controlled PIVOT-09 trial investigated the efficacy and safety of BEMPEG plus nivolumab (NIVO) as first-line treatment for advanced/metastatic clear cell renal cell carcinoma (ccRCC) with intermediate-/poor-risk disease., Methods: Patients with previously untreated advanced/metastatic ccRCC were randomly assigned (1:1) to BEMPEG plus NIVO, or investigator's choice of tyrosine kinase inhibitor (TKI; sunitinib or cabozantinib). Coprimary end points were objective response rate (ORR) by blinded independent central review and overall survival (OS) in patients with International Metastatic RCC Database Consortium (IMDC) intermediate-/poor-risk disease., Results: Overall, 623 patients were randomly assigned to BEMPEG plus NIVO (n = 311) or TKI (n = 312; sunitinib n = 225, cabozantinib n = 87), of whom 514 (82.5%) had IMDC intermediate-/poor-risk disease. In patients with IMDC intermediate-/poor-risk disease, ORR with BEMPEG plus NIVO versus TKI was 23.0% (95% CI, 18.0 to 28.7) versus 30.6% (95% CI, 25.1 to 36.6; difference, -7.7 [95% CI, -15.2 to -0.2]; P = .0489), and median OS was 29.0 months versus not estimable (hazard ratio, 0.82 [95% CI, 0.61 to 1.10]; P = .192), respectively. More frequent all-grade treatment-related adverse events (TRAEs) with BEMPEG plus NIVO versus TKI included pyrexia (32.6% v 2.0%) and pruritus (31.3% v 8.8%). Grade 3/4 TRAEs were less frequent with BEMPEG plus NIVO (25.8%) versus TKI (56.5%)., Conclusion: First-line BEMPEG plus NIVO for advanced/metastatic ccRCC did not improve efficacy in patients with intermediate-/poor-risk disease but led to fewer grade 3/4 TRAEs versus TKI.

High-dose (HD) IL-2 was the first immuno-oncology agent approved for treating advanced renal cell carcinoma and metastatic melanoma, but its use was limited because of substantial toxicities. Multiple next-generation IL-2 agents are being developed to improve tolerability. However, a knowledge gap still exists for the genomic markers that define the target pharmacology for HD IL-2 itself. In this retrospective observational study, we collected PBMC samples from 23 patients with metastatic renal cell carcinoma who were treated with HD IL-2 between 2009 and 2015. We previously reported the results of flow cytometry analyses. In this study, we report the results of our RNA-sequencing immunogenomic survey, which was performed on bulk PBMC samples from immediately before (day 1), during (day 3), and after treatment (day 5) in cycle 1 and/or cycle 2 of the first course of HD IL-2. As part of a detailed analysis of immunogenomic response to HD IL-2 treatment, we analyzed the changes in individual genes and immune gene signatures. By day 3, most lymphoid cell types had transiently decreased, whereas myeloid transcripts increased. Although most genes and/or signatures generally returned to pretreatment expression levels by day 5, certain ones representative of B cell, NK cell, and T cell proliferation and effector functions continued to increase, along with B cell (but not T cell) oligoclonal expansion. Regulatory T cells progressively expanded during and after treatment. They showed strong negative correlation with myeloid effector cells. This detailed RNA-sequencing immunogenomic survey of IL-2 pharmacology complements results of prior flow cytometry analyses. These data provide valuable pharmacological context for assessing PBMC gene expression data from patients dosed with IL-2-related compounds that are currently in development., (Copyright © 2024 by The American Association of Immunologists, Inc.)

Purpose: Simlukafusp alfa [fibroblast activation protein α-targeted IL2 variant (FAP-IL2v)], a tumor-targeted immunocytokine, comprising an IL2 variant moiety with abolished CD25 binding fused to human IgG1, is directed against fibroblast activation protein α. This phase I, open-label, multicenter, dose-escalation, and extension study (NCT02627274) evaluated the safety, pharmacokinetics, pharmacodynamics, and antitumor activity of FAP-IL2v in patients with advanced/metastatic solid tumors., Patients and Methods: Participants received FAP-IL2v intravenously once weekly. Dose escalation started at 5 mg; flat dosing (≤25 mg) and intraparticipant uptitration regimens (15/20, 20/25, 20/20/35, and 20/35/35 mg) were evaluated. Primary objectives were dose-limiting toxicities, maximum tolerated dose, recommended expansion dose, and pharmacokinetics., Results: Sixty-one participants were enrolled. Dose-limiting toxicities included fatigue (flat dose 20 mg: n = 1), asthenia (25 mg: n = 1), drug-induced liver injury (uptitration regimen 20/25 mg: n = 1), transaminase increase (20/25 mg: n = 1), and pneumonia (20/35/35 mg: n = 1). The uptitration regimen 15/20 mg was determined as the maximum tolerated dose and was selected as the recommended expansion dose. Increases in peripheral blood absolute immune cell counts were seen for all tested doses [NK cells, 13-fold; CD4+ T cells (including regulatory T cells), 2-fold; CD8+ T cells, 3.5-fold] but without any percentage change in regulatory T cells. Clinical activity was observed from 5 mg [objective response rate, 5.1% (n = 3); disease control rate, 27.1% (n = 16)]. Responses were durable [n = 3, 2.8 (censored), 6.3, and 43.4 months]., Conclusions: FAP-IL2v had a manageable safety profile and showed initial signs of antitumor activity in advanced/metastatic solid tumors., (©2024 The Authors; Published by the American Association for Cancer Research.)

Regulatory T cells (Treg), a subset of CD4 + T cells, are potent regulators of immune reactions, which have been shown to be a promising therapeutic alternative to toxic immunosuppressive drugs. Data support the utility of Treg in managing immunopathologies, including solid organ transplant rejection, graft-versus-host disease, and autoimmune disorders. Notably, reports suggest that interleukin-2 (IL-2) is critical to survival of Treg, which constitutively express high levels of CD25, that is, the IL-2 receptor α-chain, and are exquisitely sensitive to IL-2, even at very low concentrations in contrast to effector T cells, which only upregulate IL-2 receptor α-chain on activation. This has led to the notion of using low doses of exogenous IL-2 therapeutically to modulate the immune system, specifically Treg numbers and function. Here, we summarize developments of clinical experience with low-dose IL-2 (LD-IL-2) as a therapeutic agent. So far, no clinical data are available to support the therapeutic use of LD-IL-2 therapy in the solid organ transplant setting. For the latter, fine-tuning by biotechnological approaches may be needed because of the narrow therapeutic window and off-target effects of LD-IL-2 therapy and so to realize the therapeutic potential of this molecule., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)

Amyotrophic lateral sclerosis (ALS) is a devastating motor neuron disease. The immunosuppressive functions of regulatory T lymphocytes (Tregs) are impaired in ALS, and correlate to disease progression. The phase 2a IMODALS trial reported an increase in Treg number in ALS patients following the administration of low-dose (ld) interleukin-2 (IL-2). We propose a pharmacometabolomics approach to decipher metabolic modifications occurring in patients treated with ld-IL-2 and its relationship with Treg response. Blood metabolomic profiles were determined on days D1, D64, and D85 from patients receiving 2 MIU of IL-2 (n = 12) and patients receiving a placebo (n = 12). We discriminated the three time points for the treatment group (average error rate of 42%). Among the important metabolites, kynurenine increased between D1 and D64, followed by a reduction at D85. The percentage increase of Treg number from D1 to D64, as predicted by the metabolome at D1, was highly correlated with the observed value. This study provided a proof of concept for metabolic characterization of the effect of ld-IL-2 in ALS. These data could present advances toward a personalized medicine approach and present pharmacometabolomics as a key tool to complement genomic and transcriptional data for drug characterization, leading to systems pharmacology., (© 2024 The Authors. Annals of the New York Academy of Sciences published by Wiley Periodicals LLC on behalf of The New York Academy of Sciences.)

A basic mathematical model for IL-2-based cancer immunotherapy is proposed and studied. Our analysis shows that the outcome of therapy is mainly determined by three parameters, the relative death rate of CD4 + T cells, the relative death rate of CD8 + T cells, and the dose of IL-2 treatment. Minimal equilibrium tumor size can be reached with a large dose of IL-2 in the case that CD4 + T cells die out. However, in cases where CD4 + and CD8 + T cells persist, the final tumor size is independent of the IL-2 dose and is given by the relative death rate of CD4 + T cells. Two groups of in silico clinical trials show some short-term behaviors of IL-2 treatment. IL-2 administration can slow the proliferation of CD4 + T cells, while high doses for a short period of time over several days transiently increase the population of CD8 + T cells during treatment before it recedes to its equilibrium. IL-2 administration for a short period of time over many days suppresses the tumor population for a longer time before approaching its steady-state levels. This implies that intermittent administration of IL-2 may be a good strategy for controlling tumor size., Competing Interests: Declaration of competing interest On behalf of all coauthors, I state that: There is non-financial interest in this research., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Regulatory T cells (T regs ) are essential for maintaining immune homeostasis by serving as negative regulators of adaptive immune system effector cell responses. Reduced production or function of T regs has been implicated in several human autoimmune diseases. The cytokine interleukin 2 plays a central role in promoting T reg differentiation, survival, and function in vivo and may therefore have therapeutic benefits for autoimmune diseases. mRNA-6231 is an investigational, lipid nanoparticle-encapsulated, mRNA-based therapy that encodes a modified human interleukin 2 mutein fused to human serum albumin (HSA-IL2m). Herein, we report the development of a semi-mechanistic kinetic-pharmacodynamic model to quantify the relationship between subcutaneous dose(s) of mRNA-6231, HSA-IL2m protein expression, and T reg expansion in nonhuman primates. The nonclinical kinetic-pharmacodynamic model was extrapolated to humans using allometric scaling principles and the physiological basis of pharmacological mechanisms to predict the clinical response to therapy a priori. Model-based simulations were used to inform the dose selection and design of the first-in-human clinical study (NCT04916431). The modeling approach used to predict human responses was validated when data became available from the phase I clinical study. This validation indicates that the approach is valuable in informing clinical decision-making., (© 2024 Modernatx, Inc. CPT: Pharmacometrics & Systems Pharmacology published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Background: Tumor-infiltrating lymphocyte (TIL) therapy has been restricted by intensive lymphodepletion and high-dose intravenous interleukin-2 (IL-2) administration. To address these limitations, we conducted preclinical and clinical studies to evaluate the safety, antitumor activity, and pharmacokinetics of an innovative modified regimen in patients with advanced gynecologic cancer., Methods: Patient-derived xenografts (PDX) were established from a local recurrent cervical cancer patient. TILs were expanded ex vivo from minced tumors without feeder cells in the modified TIL therapy regimen. Patients underwent low-dose cyclophosphamide lymphodepletion followed by TIL infusion without intravenous IL-2. The primary endpoint was safety; the secondary endpoints included objective response rate, duration of response, and T cell persistence., Results: In matched patient-derived xenografts (PDX) models, homologous TILs efficiently reduced tumor size (p < 0.0001) and underwent IL-2 absence in vivo. In the clinical section, all enrolled patients received TIL infusion using a modified TIL therapy regimen successfully with a manageable safety profile. Five (36%, 95% CI 16.3-61.2) out of 14 evaluable patients experienced objective responses, and three complete responses were ongoing at 19.5, 15.4, and 5.2 months, respectively. Responders had longer overall survival (OS) than non-responders (p = 0.036). Infused TILs showed continuous proliferation and long-term persistence in all patients and showed greater proliferation in responders which was indicated by the Morisita overlap index (MOI) of TCR clonotypes between infused TILs and peripheral T cells on day 14 (p = 0.004) and day 30 (p = 0.004). Higher alteration of the CD8 + /CD4 + ratio on day 14 indicated a longer OS (p = 0.010)., Conclusions: Our modified TIL therapy regimen demonstrated manageable safety, and TILs could survive and proliferate without IL-2 intravenous administration, showing potent efficacy in patients with advanced gynecologic cancer., Trial Registration: NCT04766320, Jan 04, 2021., (© 2024. The Author(s).)

Patients with advanced cancer, previously treated with immune checkpoint blockade therapy, may retain residual treatment when undergoing the initial infusion of experimental monotherapy in phase 1 clinical trials. ANV419, an antibody-cytokine fusion protein, combines interleukin-2 (IL-2) with an anti-IL-2 monoclonal antibody, aiming to stimulate the expansion of CD8 T and natural killer lymphocytes while restricting regulatory T lymphocytes. In the recent publication of the phase 1 dose escalation study of ANV419, a notable gap exists in detailed information regarding patients' prior antitumoral treatments, specifically programmed death-1/programmed death-ligand 1 (PD-1/PD-L1) targeted monoclonal antibodies. Some patients likely retained residual anti-PD-1/PD-L1 monoclonal antibodies, potentially influencing the outcomes of ANV419. In a separate clinical cohort, we retrospectively measured the residual concentration of nivolumab and pembrolizumab, revealing persistent serum concentrations of anti-PD-1/PD-L1 antibodies even months after treatment cessation. This underscores the importance of comprehensively documenting prior immunotherapy details in clinical trials. Such information is crucial for understanding potential interactions that may impact both immunological and clinical effects., Competing Interests: Competing interests: LM, DC, JC, JD, SB have not conflict of interest to declare. KO, AM, SP, YL, SC and F-XD, as part of the Drug Development Department (DITEP): Principal/sub-investigator of Clinical Trials for AbbVie, Adaptimmune, Adlai Nortye USA Inc, Aduro Biotech, Agios Pharmaceuticals, Amgen, Anaveon, Argen-X Bvba, Astex Pharmaceuticals, AstraZeneca Ab, Aveo, Basilea Pharmaceutica International Ltd, Bayer Healthcare Ag, Bbb Technologies Bv, Beigene, BicycleTx Ltd, Blueprint Medicines, Boehringer Ingelheim, Boston Pharmaceuticals, Bristol Myers Squibb, Ca, Celgene Corporation, Chugai Pharmaceutical Co, Clovis Oncology, Cullinan-Apollo, Curevac, Daiichi Sankyo, Debiopharm, Eisai, Eisai Limited, Eli Lilly, Exelixis, Faron Pharmaceuticals Ltd, Forma Tharapeutics, Gamamabs, Genentech, GlaxoSmithKline, H3 Biomedicine, Hoffmann La Roche Ag, Imcheck Therapeutics, Innate Pharma, Institut De Recherche Pierre Fabre, Iris Servier, Iteos Belgium SA, Janssen Cilag, Janssen Research Foundation, Kura Oncology, Kyowa Kirin Pharm. Dev, Lilly France, Loxo Oncology, Lytix Biopharma As, Medimmune, Menarini Ricerche, Merck Sharp & Dohme Chibret, Merrimack Pharmaceuticals, Merus, Millennium Pharmaceuticals, Molecular Partners Ag, Nanobiotix, Nektar Therapeutics, Novartis Pharma, Octimet Oncology Nv, Oncoethix, Oncopeptides, Orion Pharma, Ose Pharma, Pfizer, Pharma Mar, Pierre Fabre, Medicament, Roche, Sanofi Aventis, Seattle Genetics, Sotio A.S, Syros Pharmaceuticals, Taiho Pharma, Tesaro, Turning Point Therapeutics, Xencor. Research Grants from AstraZeneca, BMS, Boehringer Ingelheim, GSK, INCA, Janssen Cilag, Merck, Novartis, Pfizer, Roche, Sanofi. Non-financial support (drug supplied) from AstraZeneca, Bayer, BMS, Boringher Ingelheim, GSK, Medimmune, Merck, NH TherAGuiX, Pfizer, Roche., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Immunotherapy targeting factors related to immune imbalance has been widely employed for RA treatment. This study aimed to evaluate the efficacy and safety of low-dose interleukin (IL)-2 combined with tocilizumab (TCZ), a biologics targeting IL-6, in RA patients., Methods: Fifty adults with active RA who met the criteria with complete clinical data were recruited, and divided into three groups: control group (n=15), IL-2 group (n=26), and IL-2+TCZ group (n=9). In addition to basic treatment, participants in the IL-2 group received IL-2 (0.5 MIU/day), while participants in the IL-2+TCZ group received IL-2 (0.5 MIU/day) along with one dose of TCZ (8 mg/kg, maximum dose: 800 mg). All subjects underwent condition assessment, laboratory indicators and safety indicators detection, and records before treatment and one week after treatment., Results: Compared with the baseline, all three groups showed significant improvement in disease conditions, as evidenced by significantly reduced disease activity indicators. The low-dose IL-2 and combination treatment groups demonstrated a violent proliferation of Tregs, while the absolute number of Th1, Th2, and Th17 cells in the latter group showed a decreasing trend. The decrease in the Th17/Treg ratio was more pronounced in the IL-2+TCZ groups. No significant adverse reactions were observed in any of the patients., Conclusion: Exogenous low doses of IL-2 combined TCZ were found to be safe and effective in reducing effector T cells and appropriately increasing Treg levels in RA patients with high effector T cell levels. This approach helps regulate immune homeostasis and contributes to the prevention of disease deterioration., Clinical Trial Registration: https://www.chictr.org.cn/showprojEN.html?proj=13909, identifier ChiCTR-INR-16009546., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Zhang, Chen, Wang, Shao, Cheng, Pei, Su, Zhang and Li.)

Background: Despite recent advances in immunotherapy, a substantial population of late-stage melanoma patients still fail to achieve sustained clinical benefit. Lack of translational preclinical models continues to be a major challenge in the field of immunotherapy; thus, more optimized translational models could strongly influence clinical trial development. To address this unmet need, we designed a preclinical model reflecting the heterogeneity in melanoma patients' clinical responses that can be used to evaluate novel immunotherapies and synergistic combinatorial treatment strategies. Using our all-autologous humanized melanoma mouse model, we examined the efficacy of a novel engineered interleukin 2 (IL-2)-based cytokine variant immunotherapy., Methods: To study immune responses and antitumor efficacy for human melanoma tumors, we developed an all-autologous humanized melanoma mouse model using clinically annotated, matched patient tumor cells and peripheral blood mononuclear cells (PBMCs). After inoculating immunodeficient NSG mice with patient tumors and an adoptive cell transfer of autologous PBMCs, mice were treated with anti-PD-1, a novel investigational engineered IL-2-based cytokine (nemvaleukin), or recombinant human IL-2 (rhIL-2). The pharmacodynamic effects and antitumor efficacy of these treatments were then evaluated. We used tumor cells and autologous PBMCs from patients with varying immunotherapy responses to both model the diversity of immunotherapy efficacy observed in the clinical setting and to recapitulate the heterogeneous nature of melanoma., Results: Our model exhibited long-term survival of engrafted human PBMCs without developing graft-versus-host disease. Administration of an anti-PD-1 or nemvaleukin elicited antitumor responses in our model that were patient-specific and were found to parallel clinical responsiveness to checkpoint inhibitors. An evaluation of nemvaleukin-treated mice demonstrated increased tumor-infiltrating CD4 + and CD8 + T cells, preferential expansion of non-regulatory T cell subsets in the spleen, and significant delays in tumor growth compared with vehicle-treated controls or mice treated with rhIL-2., Conclusions: Our model reproduces differential effects of immunotherapy in melanoma patients, capturing the inherent heterogeneity in clinical responses. Taken together, these data demonstrate our model's translatability for novel immunotherapies in melanoma patients. The data are also supportive for the continued clinical investigation of nemvaleukin as a novel immunotherapeutic for the treatment of melanoma., Competing Interests: Competing interests: JL, RW and HL hold stock in Alkermes. Research performed at the Cleveland Clinic in the laboratory of BRG was funded by Alkermes., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: To evaluate the effect of low-dose recombinant interleukin-2 (rIL-2) therapy on immunocyte subsets and its side effects in children with solid tumor., Methods: A total of 22 children (11 males and 11 females) with solid tumor in our department from December 2012 to November 2017 were selected, with a median age of 9 (3-16) years old when starting IL-2 therapy. ALL surgeries and chemotherapy of children had been completed before low-dose rIL-2 therapy, and 17 cases achieved complete remission (CR) and 5 cases achieved partial remission (PR). A low-dose rIL-2 therapy was given 1 month after chemotherapy for 1 year: 4×10 5 IU/(m 2 ·d), s.c. for every other day, 3 times per week. The immunocyte subsets were detected every 3 months until the end of treatment, meanwhile, disease condition and therapy-related side effects were followed up., Results: After low-dose rIL-2 therapy in 22 children, the absolute values of CD3 + T cells, CD3 - CD56 + natural killer cells, CD3 + CD4 + helper T cells (Th) and CD3 + CD8 + cytotoxic T cells were up-regulated remarkably, as well as Th/suppressor T cells (all P < 0.05). While, there were no significant differences in absolute value and proportion of CD4 + CD25 + CD127 - Treg cells during therapy. Among the 17 children who achieved CR before rIL-2 therapy, 14 cases continued to maintain CR after therapy, while 3 cases relapsed, and with 2 died after treatment abandonment. The 5 children who achieved PR before low-dose rIL-2 therapy were evaluated CR by PET/CT scan after treatment. In the early stage of low-dose rIL-2 therapy, 1 child developed skin rashes at the injection sites, and 2 children ran a slight to mild transient fever. Their symptoms disappeared without any organ damage after symptomatic treatment., Conclusion: Low-dose rIL-2 therapy has good drug tolerance, and changes the distribution of anti-tumor immune-cell subgroup in peripheral blood of children with solid tumor remarkably without up-regulation of absolute value and ratio of Treg cells.

Importance: Chickens immunized with the infectious laryngotracheitis chicken embryo origin (CEO) vaccine (Medivac, PT Medion Farma Jaya) experience adverse reactions, hindering its safety and effective use in poultry flocks. To improve the effect of the vaccine, we sought to find a strategy to alleviate the respiratory reactions associated with the vaccine. Here, we confirmed that co-administering the CEO vaccine with chIL-2 by oral delivery led to significant alleviation of the vaccine reactions in chickens after immunization. Furthermore, we found that the co-administration of chIL-2 with the CEO vaccine reduced the clinical signs of the CEO vaccine while enhancing natural killer cells and cytotoxic T lymphocyte response to decrease viral loads in their tissues, particularly in the trachea and conjunctiva. Importantly, we demonstrated that the chIL-2 treatment can ameliorate the replication of the CEO vaccine without compromising its effectiveness. This study provides new insights into further applications of chIL-2 and a promising strategy for alleviating the adverse reaction of vaccines., Competing Interests: The authors declare no conflict of interest.

As a pleiotropic cytokine, interleukin-2 (IL-2) can effectively regulate lymphocyte proliferation, survival, and active antitumor immune responses in tumor microenvironments. Although the ability of IL-2 to boost immune responses was reported in cancer patients, its short circulating half-life and high toxicity hinder its broad and continual clinical application. Herein, we developed a novel tumor target agent by fusing pH low insertion peptides (pHLIP) with IL-2, forming the fusion protein pHLIP-IL2. Based on the low pH insertion property of pHLIP, the pHLIP-IL2 fusion protein could be selectively delivered to the acidic tumor microenvironments and then promote the proliferation of killer immune cells to elicit tumor regression. We found that pHLIP-IL2 fusion proteins can be significantly enriched in tumor tissues and can effectively reduce tumor size in diverse tumor models, including breast cancer and melanoma, without apparent adverse effects. These data suggest that the pHLIP-IL2 fusion protein may be a promising solution for the continual and extensive application of IL-2, and pHLIP-IL2 is a potential and valuable therapeutic drug for cancer patients with antitumor immunotherapy.

The majority of patients with chronic graft-versus-host disease (cGVHD) are steroid refractory (SR), creating a need for safe and effective therapies. Subcutaneous low-dose interleukin-2 (LD IL-2), which preferentially expands CD4+ regulatory T cells (Tregs), has been evaluated in 5 clinical trials at our center with partial responses (PR) in ∼50% of adults and 82% of children by week 8. We now report additional real-world experience with LD IL-2 in 15 children and young adults. We conducted a retrospective chart review of patients with SR-cGVHD at our center who received LD IL-2 from August 2016 to July 2022 not on a research trial. The median age at start of LD IL-2 was 10.4 years (range, 1.2-23.2 years) at a median of 234 days from cGVHD diagnosis (range, 11-542 days). Patients had a median of 2.5 (range, 1-3) active organs at LD IL-2 start and received a median of 3 (range, 1-5) prior therapies. The median duration of LD IL-2 therapy was 462 days (range, 8-1489 days). Most patients received 1 × 106 IU/m2 per day. There were no serious adverse effects. The overall response rate in 13 patients who received >4 weeks of therapy was 85% (complete response, n = 5; PR, n = 6) with responses in diverse organs. Most patients significantly weaned corticosteroids. Tregs preferentially expanded with a median peak fold increase of 2.8 in the ratio of Tregs to CD4+ conventional T cells (range, 2.0-19.8) by 8 weeks on therapy. LD IL-2 is a well-tolerated, steroid-sparing agent with a high response rate in children and young adults with SR-cGVHD., (© 2023 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Face transplantation is a life-changing procedure for patients with severe composite facial defects. However, it is hampered by high acute rejection rates due to the immunogenicity of skin allograft and toxicity linked to high doses of immunosuppression. To reduce immunosuppression-associated complications, we, for the first time in face transplant recipients, used low-dose interleukin 2 (IL-2) therapy to expand regulatory T cells (Tregs) in vivo and to enhance immune modulation, under close immunological monitoring of peripheral blood and skin allograft. Low-dose IL-2 achieved a sustained expansion (∼4-fold to 5-fold) of circulating Tregs and a reduction (∼3.5-fold) of B cells. Post-IL-2 Tregs exhibited greater suppressive function, characterized by higher expression of TIM-3 and LAG3co-inhibitory molecules. In the skin allograft, Tregs increased after low-dose IL-2 therapy. IL-2 induced a distinct molecular signature in the allograft with reduced cytotoxicity-associated genes (granzyme B and perforin). Two complications were observed during the trial: one rejection event and an episode of autoimmune hemolytic anemia. In summary, this initial experience demonstrated that low-dose IL-2 therapy was not only able to promote immune regulation in face transplant recipients but also highlighted challenges related to its narrow therapeutic window. More specific targeted Treg expansion strategies are needed to translate this approach to the clinic., (Copyright © 2023 American Society of Transplantation & American Society of Transplant Surgeons. Published by Elsevier Inc. All rights reserved.)

Background: It is now accepted that immune tolerance disorders caused by inadequate Treg cell function or number are important factors in the development and progression of rheumatic diseases. There is increasing evidence that ld IL-2 treatment increases the proportion of Treg cells in patients' peripheral blood, but this conclusion is still controversial. Here, we performed a meta-analysis of reports documenting the proportion of Treg cells and the rate of adverse events in patients with rheumatic disease before and after the administration of ld IL-2 to better understand its effect and safety on Treg cells in the field of rheumatic diseases., Methods: We systematically searched PubMed, Embase, Scopus, Cochrane Library, and Web of science databases up to 15th November 2022 and identified studies that reported the proportion of peripheral blood Treg cells before and after ld IL-2 treatment in patients with rheumatic disease. Random-effects model was used to perform a meta-analysis of Treg cell proportions before and after ld IL-2 administration, and a meta-regression analysis was performed to explore heterogeneity. Inconsistency was evaluated using the I-squared index (I 2 ), and publication bias was assessed by examining funnel plot asymmetry using the Egger tests., Results: Eighteen studies involving 1608 patients were included in the meta-analysis. The proportion of Treg cells in peripheral blood of these patients increased significantly after receiving ld IL-2 treatment [1.07 (95% CI 0.86,1.27), p < 0.001, I 2  = 67.3%]. Next, Meta-regression was performed for 5 variables including publish year, disease type, trail type and dosage and duration of the medication. The results suggest that these variables do not lead to high heterogeneity. (p = 0.698, 0.267, 0.502, 0.843, 0.560, respectively). And finally, statistical analysis showed no difference in adverse reactions between ld IL-2 group and control group in treatment [1.06 (95% CI 0.86,1.31), p = 0.586, I2 = 53.8%], which is unreliable because the data is so small., Conclusions: Ld IL-2 does increase the proportion of peripheral blood Treg cells in patients with rheumatism, and single and cumulative doses must be considered when using ld IL-2. In addition, more studies on the safety of ld IL-2 are urgently needed., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Bempegaldesleukin (BEMPEG: NKTR-214) is an immunostimulatory IL-2 cytokine prodrug engineered to deliver a controlled, sustained and preferential IL-2 pathway signal. Nivolumab (NIVO), a PD-1 inhibitor, has been shown to prolong survival in patients with advanced melanoma and recurrence-free survival in the adjuvant setting. PIVOT-02 showed that BEMPEG plus NIVO was well-tolerated and demonstrated clinical activity as first-line therapy in metastatic melanoma. PIVOT-12 is a randomized, phase III, global, multicenter, open-label study comparing adjuvant therapy with BEMPEG plus NIVO versus NIVO alone in adult and adolescent patients with completely resected cutaneous stage III/IV melanoma at high risk of recurrence. The primary objective is to compare the efficacy, as measured by recurrence-free survival, of BEMPEG plus NIVO versus NIVO.

BACKGROUND: Atherosclerosis is a chronic inflammatory disease of the artery wall. Regulatory T cells (Tregs) limit inflammation and promote tissue healing. Low doses of interleukin (IL)-2 have the potential to increase Tregs, but its use is contraindicated for patients with ischemic heart disease. METHODS: In this randomized, double-blind, placebo-controlled, dose-escalation trial, we tested low-dose subcutaneous aldesleukin (recombinant IL-2), given once daily for 5 consecutive days. In study part A, the primary end point was safety, and patients with stable ischemic heart disease were randomly assigned to receive placebo or to one of five dose groups (range, 0.3 to 3.0 × 106 IU daily). In study part B, patients with acute non-ST elevation myocardial infarction or unstable angina were randomly assigned to receive placebo or to one of two dose groups (1.5 and 2.5 × 106 IU daily). The coprimary end points were safety and the dose required to increase circulating Tregs by 75%. Single-cell RNA-sequencing of circulating immune cells was used to provide a mechanistic assessment of the effects of aldesleukin. RESULTS: Forty-four patients were randomly assigned to either study part A (n=26) or part B (n=18). In total, 3 patients withdrew before dosing, 27 received active treatment, and 14 received placebo. The majority of adverse events were mild. Two serious adverse events occurred, with one occurring after drug administration. In parts A and B, there was a dose-dependent increase in Tregs. In part B, the estimated dose to achieve a 75% increase in Tregs was 1.46 × 106 IU (95% confidence interval, 1.06 to 1.87). Single-cell RNA-sequencing demonstrated the engagement of distinct pathways and cell–cell interactions. CONCLUSIONS: In this phase 1b/2a study, low-dose IL-2 expanded Tregs without adverse events of major concern. Larger trials are needed to confirm the safety and to further evaluate the efficacy of low-dose IL-2 as an anti-inflammatory therapy for patients with ischemic heart disease. (Funded by the Medical Research Council, the British Heart Foundation, and others; ClinicalTrials.gov number, NCT03113773)

Patients with chronic hepatitis B (CHB) undergoing interferon (IFN)-α-based therapies often exhibit a poor HBeAg serological response. Thus, there is an unmet need for new therapies aimed at CHB. This study comprised two clinical trials, including 130 CHB patients, who were treatment-naïve; in the first, 92 patients were systematically analyzed ex vivo for interleukin-2 receptor (IL-2R) expression and inhibitory molecules expression after receiving Peg-IFN-α-2b therapy. In our second clinical trial, 38 non-responder patients, in whom IFN-α therapy had failed, were treated with or without low-dose IL-2 for 24 weeks. We then examined the hepatitis B virus (HBV)-specific CD8 + T-cell response and the clinical outcome, in these patients. Although the majority of the participants undergoing Peg-IFN-α-2b therapy were non-responders, we observed a decrease in CD25 expression on their CD4 + T cells, suggesting that IFN-α therapy may provide a rationale for sequential IL-2 treatment without increasing regulatory T cells (Tregs). Following sequential therapy with IL-2, we demonstrated that the non-responders experienced a decrease in the numbers of Tregs and programmed cell death protein 1 (PD-1) expression. In addition, sequential IL-2 administration rescued effective immune function, involving signal transducer and activator of transcription 1 (STAT1) activation. Importantly, IL-2 therapy significantly increased the frequency and function of HBV-specific CD8 + T cells, which translated into improved clinical outcomes, including HBeAg seroconversion, among the non-responder CHB patients. Our findings suggest that sequential IL-2 therapy shows efficacy in rescuing immune function in non-responder patients with refractory CHB., (© 2021. The Author(s).)

Nemvaleukin alfa (nemvaleukin, ALKS 4230) is a novel cytokine created by the fusion of circularly permuted interleukin-2 (IL-2) to the IL-2R α subunit of the IL-2 receptor (IL-2R) complex that confers selectivity for the intermediate-affinity IL-2R expressed on CD8 + T cells and natural killer (NK) cells. The pharmacokinetics and selective pharmacodynamic properties of nemvaleukin have been demonstrated using in vitro and in vivo mouse models. The pharmacokinetic/pharmacodynamic effects of nemvaleukin on immune cell subtypes were evaluated in cynomolgus monkeys after intravenous and subcutaneous administration to inform dose selection and predict pharmacodynamic effects in humans. Male drug-naïve cynomolgus monkeys ( N = 15) were administered either single-dose (0.3 mg/kg i.v.; 0.3 mg/kg or 1.0 mg/kg s.c.) or repeated doses (0.1 mg/kg i.v. on days 1-5 or 0.5 mg/kg s.c. on days 1 and 4) of nemvaleukin. Serial blood samples were collected for pharmacokinetic assessment, immunophenotyping by flow cytometry, and profiling of serum cytokines. Repeat-dose subcutaneous administration of nemvaleukin with less frequent dosing resulted in total systemic exposure and trough serum concentrations comparable to those seen with intravenous administration, with lower peak serum concentrations. Transient elevation of interferon- γ and IL-6 peaked at 2 and 8 hours after intravenous and subcutaneous administration, respectively. Selective expansion of immunoprotective central memory, effector memory, terminal effector CD8 + T cells, and CD56 + NK cells, and minimal expansion of immunosuppressive CD4 + CD25 + FoxP3 + regulatory T cells was observed after both intravenous and subcutaneous administration. These data support the ongoing clinical evaluation of intravenous and subcutaneous nemvaleukin. SIGNIFICANCE STATEMENT: Administration of the novel interleukin-2 receptor agonist nemvaleukin alfa to cynomolgus monkeys resulted in selective expansion of immune effector cells, including CD8 + T and natural killer cells with minimal effects on immunosuppressive CD4 + regulatory T cells, confirming the design of nemvaleukin and highlighting its potential as a cancer immunotherapy. Subcutaneous administration of nemvaleukin achieved systemic exposure and immunostimulatory effects similar to those observed after more frequent intravenous dosing and may represent a practical alternative in a clinical setting., (Copyright © 2021 by The Author(s).)

High-dose interleukin-2 (HD IL-2) has curative potential in metastatic melanoma (MM) and renal cell carcinoma (RCC). Radiotherapy (RT) kills cancer cells and induces immunomodulatory effects. Prospective trials exploring clinical and immunological properties of combined RT/HD IL-2 are still needed. We designed a phase II, single-arm clinical trial for patients with MM and RCC. The treatment schedule consisted of 3 daily doses of 6-12 Gy of RT to 1-5 non-index metastatic fields, before IL-2 at the first and third treatment cycle. HD IL-2 was administered by continuous infusion for 72 hours and repeated every 3 weeks for up to 4 cycles, thereafter every 4 weeks for a maximum of 2 cycles. The primary endpoint was the immunological efficacy of the combined RT/HD IL-2 treatment (assessed by IFN-γ ELISPOT). Nineteen out of 22 patients were evaluable for immunological and clinical response. Partial response occurred in 3 (15.7%) patients and stable disease was observed in 7 (36.8%). The disease control rate was 52.6% after a median follow up of 39.2 months. According to Common Terminology Criteria for Adverse Events 4.0 (CTCAE 4.0), the majority of toxicities were grade 1-2. Immunological responses were frequent and detected in 16 (84.2%) patients. Increased levels of IL-8 and IL-10 in melanoma, circulating effector memory CD4+ and intratumoral CD8+ T cells in both tumor types were detected after therapy. Overall the treatment was well tolerated and immunologically active. Immunomonitoring and correlative data on tumor and peripheral blood cell subsets suggest that this combination treatment could be a promising strategy for patients progressing after standard treatments., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Bulgarelli, Piccinini, Petracci, Pancisi, Granato, de Rosa, Guidoboni, Petrini, Ancarani, Foschi, Romeo, Tontini, De Giorgi, Lolli, Gentili, Valmorri, Rossi, Ferroni, Casadei, Cortesi, Crudi and Ridolfi.)

BACKGROUNDA previous phase I study showed that the infusion of autologous Tregs expanded ex vivo into patients with recent-onset type 1 diabetes (T1D) had an excellent safety profile. However, the majority of the infused Tregs were undetectable in the peripheral blood 3 months postinfusion (Treg-T1D trial). Therefore, we conducted a phase I study (TILT trial) combining polyclonal Tregs and low-dose IL-2, shown to enhance Treg survival and expansion, and assessed the impact over time on Treg populations and other immune cells.METHODSPatients with T1D were treated with a single infusion of autologous polyclonal Tregs followed by one or two 5-day courses of recombinant human low-dose IL-2 (ld-IL-2). Flow cytometry, cytometry by time of flight, and 10x Genomics single-cell RNA-Seq were used to follow the distinct immune cell populations' phenotypes over time.RESULTSMultiparametric analysis revealed that the combination therapy led to an increase in the number of infused and endogenous Tregs but also resulted in a substantial increase from baseline in a subset of activated NK, mucosal associated invariant T, and clonal CD8+ T cell populations.CONCLUSIONThese data support the hypothesis that ld-IL-2 expands exogenously administered Tregs but also can expand cytotoxic cells. These results have important implications for the use of a combination of ld-IL-2 and Tregs for the treatment of autoimmune diseases with preexisting active immunity.TRIAL REGISTRATIONClinicalTrials.gov NCT01210664 (Treg-T1D trial), NCT02772679 (TILT trial).FUNDINGSean N. Parker Autoimmune Research Laboratory Fund, National Center for Research Resources.

Alloreactive memory cells play a critical role after a second transplant and are difficult to suppress. This study investigated the effect of an immunotherapeutic strategy that combines anti-OX40L, rapamycin (Rapa), and a low dose of IL-2 in a memory cell-based adoptive model. In this model, the median survival time (MST) of the grafts of the combined treatment group was significantly extended compared to that of the control group and other treatment groups. A similar effect was observed regarding a reduction in memory T cells (Tm) and inflammatory cytokines production. Also, the percentages of Foxp3 + regulatory T cells (Tregs) increased in our model. In addition, mounting evidence has shown CD8 + CD122 + T cells are also Tregs. We found that the group of CD8 + CD122 + PD1 + T cells was markedly increased in the combined treatment group, especially in the graft. We further demonstrated that CD8 + CD122 + PD1 + T cells could suppress activated T cells. Our data suggest that anti-OX40L combined with Rapa and a low dose of IL-2 can suppress Tm, modulate CD4 and CD8 Tregs, and induce long-term heart allograft survival in sensitized mice., (Copyright © 2021. Published by Elsevier B.V.)

To evaluate the feasibility of adoptive cell therapy (ACT) using ex vivo-expanded tumor-infiltrating lymphocytes (TILs) in Japanese patients with melanoma who failed immune-checkpoint inhibitor therapy, an open-label, single-arm, pilot study was conducted. We investigated the immunological and genetic factors of the pretreatment tumor and expanded TILs that may be associated with the clinical response. The treatment protocol comprised preparation of TIL culture, lympho-depleting non-myeloablative preconditioning with cyclophosphamide and fludarabine, TIL infusion, and intravenous administration of low-dose IL-2. Three patients of clinical subtypes mucosal, superficial spreading, and acral melanoma underwent TIL-ACT. Most severe adverse events, including fever and leukopenia, were manageable with the supportive regimen specified in the protocol, suggesting that the TIL-ACT regimen is suitable for Japanese patients with melanoma. One patient showed a short-term partial response, one relatively long-stable disease, and one experienced disease progression. Whole-exome and transcriptional sequencing of isolated tumor cells and immunohistochemical analyses before TIL-ACT revealed various immunostimulatory factors, including a high tumor mutation burden and immune cell-recruiting chemokines, as well as various immunosuppressive factors including TGF-β, VEGF, Wnt/β-catenin, and MAPK signaling and epithelial-to-mesenchymal transition, which might influence the efficacy of TIL-ACT. Our results imply mechanisms for the antitumor effect of and resistance to TIL-ACT. Further studies of immune-resistant mechanisms of TIL-ACT are warranted. This study is registered with the UMIN Clinical Trial Registry (UMIN 000011431)., (© 2021 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.)

Objectives: Systemic inflammatory and autoimmune diseases can be associated with myelodysplastic syndromes. Current treatments (steroids, immunosuppressive agents, biologics) are unsatisfactory because of their low response rate, dependence or adverse events. We aimed at evaluating the effects of low doses of IL-2 (ld-IL2) as a regulatory T-cell inducer in this context., Methods: We treated three patients with ld-IL2 with myelodysplastic syndromes and an associated dysimmune disorder (polymyalgia rheumatic, relapsing polychondritis associated with Sweet's syndrome and vasculitis with cutaneous and joint involvement, respectively). All three patients were dependent on steroids and refractory to biologics or azacitidine. They received doses of 1-1.5 million units of proleukin/day during 5 days and then every fortnight., Results: The treatment led to a clinical improvement and steroid sparing in 2/3 patients with no serious adverse events, and no progression of the disease., Conclusion: Our results support the investigation of ld-IL2 in MDS associated with immune disorders in controlled clinical studies., (© The Author(s) 2020. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objective: Multiple sclerosis (MS) is a progressive autoimmune-mediated inflammation of the central nervous system (CNS), and experimental autoimmune encephalomyelitis (EAE) is a suitable model to study the pathogenesis of MS. IL-2 has been considered as both a T cell growth factor and an anti-inflammatory cytokine. In the present study, we investigated the effects of a low dose IL-2 treatment on mouse EAE therapy., Method: The expression of IL-2 and IL-2 receptor were predicted using public microarray data and verified by real-time PCR and ELISA in mouse EAE model. Mice were injected with Myelin Oligodendrocyte Glycoprotein (35-55)(MOG 35-55 ) subcutaneously to induce EAE model. IL-2 treatment was initiated during 5 consecutive days from day 15 post MOG 35-55 immunization. Flow cytometry was applied to investigate the proportions of Th17 and Treg cells. ELISA was used to detect the concentrations of IL-17a, IFNr, IL-10 and TGFb., Results: In this study, we showed that the IL-2 treatment ameliorates the clinical severity of EAE. Flow cytometry results indicated that the therapeutic effect was related to a reduction of Th17 cells and an expansion of Treg cells in the EAE spinal cord. In vitro experiments also confirmed the anti-inflammatory effect of IL-2 in EAE-reactivated T cells., Conclusion: Low-dose IL-2 is a potential therapeutic strategy for EAE and MS., (© 2021 by the Association of Clinical Scientists, Inc.)

Background: The generation of long-term durable tumor immunity and prolonged disease-free survival depends on the ability to generate and support CD8+ central memory T-cells. Microsatellite-stable colon cancer is resistant to currently available immunotherapies; thus, development of novel mechanisms to increase both lymphocyte infiltration and central memory formation are needed to improve outcomes in these patients. We have previously demonstrated that both interleukin-2 (IL-2) and LIGHT (TNFSF14) independently enhance antitumor immune responses and hypothesize that combination immunotherapy may increase the CD8+ central memory T-cell response., Methods: Murine colorectal cancer tumors were established in syngeneic mice. Tumors were treated with control, soluble, or liposomal IL-2 at established intervals. A subset of animal tumors overexpressed tumor necrosis superfamily factor LIGHT (TNFSF14). Peripheral blood, splenic, and tumor-infiltrating lymphocytes were isolated for phenotypic studies and flow cytometry., Results: Tumors exposed to a combination of LIGHT and IL-2 experienced a decrease in tumor size compared with IL-2 alone that was not demonstrated in wild-type tumors or between other treatment groups. Combination exposure also increased splenic central memory CD8+ cells compared with IL-2 administration alone, while not increasing tumor-infiltrating lymphocytes. In the periphery, the combination enhanced levels of circulating CD8 T-cells and central memory T-cells, while also increasing circulating T-regulatory cells., Conclusions: Combination of IL-2, whether soluble or liposomal, with exposure to LIGHT results in increased CD8+ central memory cells in the spleen and periphery. New combination immunotherapy strategies that support both effector and memory T-cell functions are critical to enhancing durable antitumor responses and warrant further investigation., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Intralesional injection of interleukin-2 (IL-2) for in-transit melanoma (ITM) is associated with a high rate of complete response. However, there is a paucity of data on treatment durability and long-term outcomes., Objectives: To provide long-term data on patients with a complete response to IL-2 therapy for ITM., Methods: Consecutive patients with ITM, treated with intralesional IL-2 therapy, at the Tom Baker Cancer Center were identified from April 2009 to August 2019. All patients received at least 4 cycles (every 2 weeks) of IL-2 (5 MIU/mL). Complete response was defined as sustained (ie, 3 months) clinical complete remission of all known in-transit disease., Results: Sixty-five patients were treated with curative intent for in-transit disease with intralesional IL-2. Complete clinical response was identified in 44.6% (29/65). In this subset of patients, the median number of lesions per patient was 9 (range 1-40). The median total dose of IL-2 was 0.8 mL (IQR 0.4-1.5) per lesion. One patient received isolated limb infusion and 13.8% (4/29) received systemic immunotherapy as part of their initial management. At a median follow-up of 27 months (IQR 16-59), 34.5% (10/29) developed recurrent disease. Of these patients, 50.0% (5/10) presented with synchronous in-transit and distant metastases. The median time to recurrence was 10.5 months (IQR 5.8-16.3)., Conclusion: With long-term follow-up, 65.5% of complete responders have a durable response to intralesional IL-2 therapy. In this cohort of patients, local in-transit recurrence is most likely to occur within 12 months and is often associated with concomitant distant disease.

Tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) are two cytokines involved in the perpetuation of the chronic inflammation state characterizing rheumatoid arthritis (RA). Significant advances in the treatment of this pathology have been made over the past ten years, partially through the development of anti-TNF and anti-IL-1 therapies. However, major side effects still persist and new alternative therapies should be considered. The formulation of the micro-immunotherapy medicine (MIM) 2LARTH ® uses ultra-low doses (ULD) of TNF-α, IL-1β, and IL-2, in association with other immune factors, to gently restore the body's homeostasis. The first part of this review aims at delineating the pivotal roles played by IL-1β and TNF-α in RA physiopathology, leading to the development of anti-TNF and anti-IL-1 therapeutic agents. In a second part, an emphasis will be made on explaining the rationale of using multiple therapeutic targets, including both IL-1β and TNF-α in 2LARTH ® medicine. Particular attention will be paid to the ULD of those two main pro-inflammatory factors in order to counteract their overexpression through the lens of their molecular implication in RA pathogenesis.

E7777 is a recombinant cytotoxic fusion protein composed of the diphtheria toxin fragments A and B and human interleukin-2. It shares an amino acid sequence with denileukin diftitox, but has improved purity and an increased percentage of active monomer. We undertook a multicenter, single-arm phase II study of E7777 in patients with relapsed or refractory peripheral T-cell lymphoma (PTCL) and cutaneous T-cell lymphoma (CTCL) to evaluate its efficacy, safety, pharmacokinetics, and immunogenicity. A total of 37 patients were enrolled, of which 17 and 19 patients had PTCL and CTCL, respectively, and one patient with another type of lymphoma (extranodal natural killer/T-cell lymphoma, nasal type), diagnosed by the Central Pathological Diagnosis Committee. Among the 36 patients with PTCL and CTCL, objective response rate based on the independent review was 36% (41% and 31%, respectively). The median progression-free survival was 3.1 months (2.1 months in PTCL and 4.2 months in CTCL). The common adverse events (AEs) observed were increased aspartate aminotransferase (AST) / alanine aminotransferase (ALT), hypoalbuminemia, lymphopenia, and pyrexia. Our results indicated that a 9 µg/kg/d dose of E7777 shows efficacy and a manageable safety profile in Japanese patients with relapsed or refractory PTCL and CTCL, with clinical activity observed across the range of CD25 expression. The common AEs were manageable, but increase in ALT / AST, hypoalbuminemia, and capillary leak syndrome should be carefully managed during the treatment., (© 2021 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.)

Cutaneous squamous cell carcinoma (cSCC) is the second most common non-melanoma skin cancer worldwide, with ever increasing incidence and mortality. While most patients can be treated successfully with surgical excision, cryotherapy, or radiation therapy, there exist a subset of patients with aggressive cSCC who lack adequate therapies. Among these patients are solid organ transplant recipients who due to their immunosuppression, develop cSCC at a dramatically increased rate compared to the normal population. The enhanced ability of the tumor to effectively undergo immune escape in these patients leads to more aggressive tumors with a propensity to recur and metastasize. Herein, we present a case of aggressive, multi-focal cSCC in a double organ transplant recipient to frame our discussion and current understanding of the immunobiology of cSCC. We consider factors that contribute to the significantly increased incidence of cSCC in the context of immunosuppression in this patient population. Finally, we briefly review current literature describing experience with localized therapies for cSCC and present a strong argument and rationale for consideration of an IL-2 based intra-lesional treatment strategy for cSCC, particularly in this immunosuppressed patient population., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Vidovic, Simms, Pasternak, Walsh, Peltekian, Stein, Helyer and Giacomantonio.)

Survival of patients with relapsed/refractory osteosarcoma has not improved in the last 30 years. Several immunotherapeutic approaches have shown benefit in murine osteosarcoma models, including the anti-programmed death-1 (anti-PD-1) and anti-cytotoxic T-lymphocyte antigen-4 (anti-CTLA-4) immune checkpoint inhibitors. Treatment with the T-cell growth factor interleukin-2 (IL-2) has shown some clinical benefit but has limitations due to poor tolerability. Therefore, we evaluated the efficacy of bempegaldesleukin (BEMPEG; NKTR-214), a first-in-class CD122-preferential IL-2 pathway agonist, alone and in combination with anti-PD-1 or anti-CTLA-4 immune checkpoint inhibitors in metastatic and orthotopic murine models of osteosarcoma. Treatment with BEMPEG delayed tumor growth and increased overall survival of mice with K7M2-WT osteosarcoma pulmonary metastases. BEMPEG also inhibited primary tumor growth and metastatic relapse in lungs and bone in the K7M3 orthotopic osteosarcoma mouse model. In addition, it enhanced therapeutic activity of anti-CTLA-4 and anti-PD-1 checkpoint blockade in the DLM8 subcutaneous murine osteosarcoma model. Finally, BEMPEG strongly increased accumulation of intratumoral effector T cells and natural killer cells, but not T-regulatory cells, resulting in improved effector:inhibitory cell ratios. Collectively, these data in multiple murine models of osteosarcoma provide a path toward clinical evaluation of BEMPEG-based regimens in human osteosarcoma., (© 2020 The Authors. International Journal of Cancer published by John Wiley & Sons Ltd on behalf of Union for International Cancer Control.)

Purpose: Previously our randomized phase III trial demonstrated that immunotherapy including dinutuximab, a chimeric anti-GD2 mAb, GM-CSF, and IL2 improved survival for children with high-risk neuroblastoma that had responded to induction and consolidation therapy. These results served as the basis for FDA approval of dinutuximab. We now present long-term follow-up results and evaluation of predictive biomarkers., Patients and Methods: Patients recieved six cycles of isotretinoin with or without five cycles of immunotherapy which consists of dinutuximab with GM-CSF alternating with IL2. Accrual was discontinued early due to meeting the protocol-defined stopping rule for efficacy, as assessed by 2-year event-free survival (EFS). Plasma levels of dinutuximab, soluble IL2 receptor (sIL2R), and human anti-chimeric antibody (HACA) were assessed by ELISA. Fcγ receptor 2A and 3A genotypes were determined by PCR and direct sequencing., Results: For 226 eligible randomized patients, 5-year EFS was 56.6 ± 4.7% for patients randomized to immunotherapy ( n = 114) versus 46.1 ± 5.1% for those randomized to isotretinoin only ( n = 112; P = 0.042). Five-year overall survival (OS) was 73.2 ± 4.2% versus 56.6 ± 5.1% for immunotherapy and isotretinoin only patients, respectively ( P = 0.045). Thirteen of 122 patients receiving dinutuximab developed HACA. Plasma levels of dinutuximab, HACA, and sIL2R did not correlate with EFS/OS, or clinically significant toxicity. Fcγ receptor 2A and 3A genotypes did not correlate with EFS/OS., Conclusions: Immunotherapy with dinutuximab improved outcome for patients with high-risk neuroblastoma. Early stoppage for efficacy resulted in a smaller sample size than originally planned, yet clinically significant long-term differences in survival were observed., (©2021 American Association for Cancer Research.)

IL-2 is the master-regulator cytokine for T cell dependent responses and is crucial for proliferation and survival of T cells. However, IL-2-based treatments remained marginal, in part due to short half-life. Thus, we aimed to extend IL-2 half-life by flanking the IL-2 core with sequences derived from the extensively glycosylated hinge region of the NCR2 receptor. We termed this modified IL-2: "S2A". Importantly, S2A blood half-life was extended 14-fold compared to the clinical grade IL-2, Proleukin. Low doses inoculation of S2A significantly enhanced induction of Tregs (CD4 + Regulatory T cells) in vivo, as compared to Proleukin, while both S2A and Proleukin induced low levels of CD8 + T cells. In a B16 metastatic melanoma model, S2A treatment was unable to reduce the metastatic capacity of B16 melanoma, while enhancing induction and recruitment of Tregs, compared to Proleukin. Conversely, in two autoimmune models, rheumatoid arthritis and DSS-induced colitis, S2A treatment significantly reduced the progression of disease compared to Proleukin. Our results suggest new avenues for generating long-acting IL-2 for long-standing treatment and a new technique for manipulating short-life proteins for clinical and research uses.

High-dose IL-2 induces cancer regression but its therapeutic use is limited due to high toxicities resulting from its broad cell targeting. In one strategy to overcome this limitation, IL-2 has been modified to selectively target the intermediate affinity IL-2R that broadly activates memory-phenotypic CD8 + T and NK cells, while minimizing Treg-associated tolerance. In this study, we modeled an alternative strategy to amplify tumor antigen-specific TCR transgenic CD8 + T cells through limited application of a long-acting IL-2 fusion protein, mIL-2/mCD25, which selectively targets the high-affinity IL-2R. Here, mice were vaccinated with a tumor antigen and high-dose mIL-2/mCD25 was applied to coincide with the induction of the high affinity IL-2R on tumor-specific T cells. A single high dose of mIL-2/mCD25, but not an equivalent amount of IL-2, amplified the frequency and function of tumor-reactive CD8 + T effector (Teff) and memory cells. These mIL-2/mCD25-dependent effects relied on distinctive requirements for TLR signals during priming of CD8 + tumor-specific T cells. The mIL-2/mCD25-amplified tumor-reactive effector and memory T cells supported long-lasting antitumor responses to B16-F10 melanoma. This regimen only transiently increased Tregs, yielding a favorable Teff-Treg ratio within the tumor microenvironment. Notably, mIL-2/mCD25 did not increase non-tumor-specific Teff or NK cells within tumors, further substantiating the specificity of mIL-2/mCD25 for tumor antigen-activated T cells. Thus, the selectivity and persistence of mIL-2/mCD25 in conjunction with a tumor vaccine supports antitumor immunity through a mechanism that is distinct from recombinant IL-2 or IL-2-based biologics that target the intermediate affinity IL-2R.

An important component of research using animal models is ensuring rigor and reproducibility. This study was prompted after two experimenters performing virtually identical studies obtained different results when syngeneic B78 murine melanoma cells were implanted into the skin overlying the flank and treated with an in situ vaccine (ISV) immunotherapy. Although both experimenters thought they were using identical technique, we determined that one was implanting the tumors intradermally (ID) and the other was implanting them subcutaneously (SC). Though the baseline in vivo immunogenicity of tumors can depend on depth of their implantation, the response to immunotherapy as a function of tumor depth, particularly in immunologically 'cold' tumors, has not been well studied. The goal of this study was to evaluate the difference in growth kinetics and response to immunotherapy between identically sized melanoma tumors following ID versus SC implantation. We injected C57BL/6 mice with syngeneic B78 melanoma cells either ID or SC in the flank. When tumors reached 190-230 mm 3 , they were grouped into a 'wave' and treated with our previously published ISV regimen (12 Gy local external beam radiation and intratumoral hu14.18-IL2 immunocytokine). Physical examination demonstrated that ID-implanted tumors were mobile on palpation, while SC-implanted tumors became fixed to the underlying fascia. Histologic examination identified a critical fascial layer, the panniculus carnosus, which separated ID and SC tumors. SC tumors reached the target tumor volume significantly faster compared with ID tumors. Most ID tumors exhibited either partial or complete response to this immunotherapy, whereas most SC tumors did not. Further, the 'mobile' or 'fixed' phenotype of tumors predicted response to therapy, regardless of intended implantation depth. These findings were then extended to additional immunotherapy regimens in four separate tumor models. These data indicate that the physical 'fixed' versus 'mobile' characterization of the tumors may be one simple method of ensuring homogeneity among implanted tumors prior to initiation of treatment. Overall, this short report demonstrates that small differences in depth of tumor implantation can translate to differences in response to immunotherapy, and proposes a simple physical examination technique to ensure consistent tumor depth when conducting implantable tumor immunotherapy experiments., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Regulatory T cells (Treg) are crucial for the maintenance of peripheral tolerance and for the control of ongoing inflammation and autoimmunity. The cytokine interleukin-2 (IL-2) is essentially required for the growth and survival of Treg in the peripheral lymphatic tissues and thus plays a vital role in the biology of Treg. Most autoimmune and rheumatic diseases exhibit disturbances in Treg biology either at a numerical or functional level resulting in an imbalance between protective and pathogenic immune cells. In addition, in some autoimmune diseases, a relative deficiency of IL-2 develops during disease pathogenesis leading to a disturbance of Treg homeostasis, which further amplifies the vicious cycle of tolerance breach and chronic inflammation. Low-dose IL-2 therapy aims either to compensate for this IL-2 deficiency to restore a physiological state or to strengthen the Treg population in order to be more effective in counter-regulating inflammation while avoiding global immunosuppression. Here we highlight key findings and summarize recent advances in the clinical translation of low-dose IL-2 therapy for the treatment of autoimmune and rheumatic diseases., Competing Interests: GR and JH are members of the steering committee for a currently ongoing multi-center phase 2 clinical trial on low-dose IL-2 therapy in SLE (LUPIL-2) sponsored by ILTOO Pharma. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Graßhoff, Comdühr, Monne, Müller, Lamprecht, Riemekasten and Humrich.)

Minimal residual disease (MRD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) heralds high risk of relapse. Whether preemptive recombinant interleukin-2 (pre-IL2) is effective for patients with late-onset MRD (LMRD) remains unknown. We retrospectively compared the efficacy and safety of pre-IL2 (n = 30) and pre-DLI (n = 25) for LMRD in patients receiving allo-HSCT for acute leukemia or myelodysplastic syndrome. The 1-year overall survival (OS) and disease-free survival (DFS) rates were 86.7% and 78.4% (P = 0.267), 83.3% and 75.6% (P = 0.329), the cumulative incidence of grades III-IV acute graft-versus-host disease (aGVHD) at 100 days post-preemptive intervention was 3.3% and 12.0% (P = 0.226) in the pre-IL2 group and pre-DLI group, respectively. The 1-year cumulative incidence of moderate/severe chronic GVHD (cGVHD), relapse (CIR), and non-relapse mortality (NRM) were 7.7% and 27.9% (P = 0.018), 13.6% and 20.0% (P = 0.561) and 3.3% and 5.5% (P = 0.321) in the two groups, respectively. No remarkable differences in CIR, OS, and DFS between the two intervention groups were found in multivariate analysis. The GVHD-free and relapse-free survival (GRFS) were better in the pre-IL2 group than in the pre-DLI group (HR = 0.31, 95% confidence interval (CI), 0.12-0.76; P = 0.011). In conclusion, preemptive low-dose IL2 and preemptive DLI yield comparable outcomes for patients with LMRD receiving allo-HSCT, in terms of aGVHD, NRM, relapse, OS, and DFS. However, preemptive low-dose IL2 has a lower incidence of moderate/severe cGVHD and a higher CRFS. Preemptive low-dose IL2 may be an alternative method for patients who develop LMRD after allo-HSCT, particularly for patients who cannot receive preemptive DLI.