High-affinity Interleukin-2 Research Articles

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

Interleukin 2 (IL-2) is a vital cytokine in the induction of T and NK cell responses, the proliferation of CD8+ T cells, and the effective treatment of human cancers such as melanoma and renal cell carcinoma. However, widespread use of this cytokine is limited due to its short half-life, severe toxicity, lack of specific tumor targeting, and activation of Treg cells mediated by high-affinity interleukin-2 receptors. In this study, a tumor-targeting LIV-1 VHH-mutIL2 immunocytokine with reduced CD25 (α chain of the high-affinity IL-2 receptor) binding activity was developed to improve IL-2 half-life by decreasing its renal infiltration in comparison with wild and mutant IL-2 molecules. The recombinant immunocytokine was designed and expressed. The biological activity of the purified fusion protein was investigated in in vitro and in vivo experiments. The fusion protein represented specific binding to MCF7 (the breast cancer cell line) and more efficient cytotoxicity than wild-type IL-2 and mutant IL-2. The PK parameters of the recombinant immunocytokine were also improved in comparison to the IL-2 molecules. The observed results showed that LIV1-mIL2 immunocytokine could be considered as an effective agent in the LIV-1-targeted treatment of cancers due to its longer half-life and stronger cytotoxicity.

Regulatory T cells in skin mediate immune privilege of the hair follicle stem cell niche.

Immune tolerance is maintained in lymphoid organs (LOs). Despite the presence of complex immune cell networks in non-LOs, it is unknown whether self-tolerance is maintained in these tissues. We developed a technique to restrict genetic recombination to regulatory T cells (Tregs) only in skin. Selective depletion of skin Tregs resulted in T cell-mediated inflammation of hair follicles (HFs). Suppression did not rely on CTLA-4, but instead on high-affinity interleukin-2 (IL-2) receptor expression by skin Tregs, functioning exclusively in a cell-extrinsic manner. In a novel model of HF stem cell (HFSC)-driven autoimmunity, we reveal that skin Tregs immunologically protect the HFSC niche. Finally, we used spatial transcriptomics to identify aberrant IL-2 signaling at stromal-HF interfaces in a rare form of human alopecia characterized by HFSC destruction and alopecia areata. Collectively, these results reveal the fundamental biology of Tregs in skin uncoupled from the systemic pool and elucidate a mechanism of self-tolerance.

Interleukin-2 PET imaging in patients with metastatic melanoma before and during immune checkpoint inhibitor therapy

PurposeImmune checkpoint inhibitors can induce a T cell–mediated anti-tumor immune response in patients with melanoma. Visualizing T cell activity using positron emission tomography (PET) might allow early insight into treatment efficacy. Activated tumor–infiltrating T cells express the high-affinity interleukin-2 receptor (IL-2R). Therefore, we performed a pilot study, using fluorine-18-labeled IL-2 ([18F]FB-IL2 PET), to evaluate whether a treatment-induced immune response can be detected.MethodsPatients with metastatic melanoma received ~ 200 MBq [18F]FB-IL2 intravenously, followed by a PET/CT scan before and during immune checkpoint inhibitor therapy. [18F]FB-IL2 uptake was measured as standardized uptake value in healthy tissues (SUVmean) and tumor lesions (SUVmax). Response to therapy was assessed using RECIST v1.1. Archival tumor tissues were used for immunohistochemical analyses of T cell infiltration.ResultsBaseline [18F]FB-IL2 PET scans were performed in 13 patients. SUVmean at baseline was highest in the kidneys (14.2, IQR: 11.6–18.0) and liver (10.6, IQR: 8.6–13.4). In lymphoid tissues, uptake was highest in spleen (10.9, IQR: 8.8–12.4) and bone marrow (2.5, IQR: 2.1–3.0). SUVmax in tumor lesions (n = 41) at baseline was 1.9 (IQR: 1.7–2.3). In 11 patients, serial imaging was performed, three at week 6, seven at week 2, and one at week 4. Median [18F]FB-IL2 tumor uptake decreased from 1.8 (IQR: 1.7–2.1) at baseline to 1.7 (IQR: 1.4–2.1) during treatment (p = 0.043). Changes in [18F]FB-IL2 tumor uptake did not correlate with response. IL-2R expression in four archival tumor tissues was low and did not correlate with baseline [18F]FB-IL2 uptake. No [18F]FB-IL2-related side effects occurred.ConclusionPET imaging of the IL-2R, using [18F]FB-IL2, is safe and feasible. In this small patient group, serial [18F]FB-IL2-PET imaging did not detect a treatment-related immune response.Trial registrationClinicaltrials.gov: NCT02922283; EudraCT: 2014-003387.20

Abstract 4508: Modulating the release rate of polyethylene glycol (PEG) polymers from interleukin-2 (IL-2) PEG conjugates to optimize anti-tumor efficacy

Abstract The cytokine interleukin-2 (IL-2) is an endogenous agonist of the IL-2 pathway that activates and expands tumor killing lymphocytes. High doses of IL-2 are needed to activate CD8 T cells and NK cells, through binding on low-affinity IL-2 receptor beta gamma subunits (IL-2Rβγ). Severe toxic side effects associated with high doses, as well as the poor PK profile of IL-2, have limited its clinical usage. In addition of the toxicities, IL-2 also stimulates proliferation and activation of regulatory T cells (Tregs) through binding on the high-affinity heterotrimeric IL-2 receptor alpha beta gamma subunits (IL-2Rαβγ), which may antagonize the intended anti-tumor immunity. We report on an IL-2 PEGylation strategy to improve the pharmacokinetic properties of IL-2. Utilizing our proprietary PEGylation technology, IL-2 was covalently connected with multiple polyethylene glycol (PEG) polymers through releasable linkers. Our technology enabled the conjugation of IL-2 with average of 5-6 polyethylene glycol (PEG) polymers in high efficiency and 80-90% isolated yield. Anti-tumor efficacy of IL-2 was optimized by modulating the hydrolysis rate of the releasable linkers connecting IL-2 and polymers. The releasable linkers used in the study had the hydrolysis rate in the range of 15 to 120 hours to release one PEG polymer from the conjugates. The conjugates with hydrolysis rate of 20-60 h showed the optimal anti-tumor efficacy in B16F10 animal model. These results suggest that our novel approach of IL-2 PEGylation may optimize IL-2 biological activity and anti-tumor efficacy. Modulating the releasable rate of the PEG polymer would optimize the pharmacokinetic properties of the released active IL-2 species and enable the optimized anti-tumor efficacy. We are currently exploring the usage of our technology platform to further engineer IL-2 as a non-IL2Rα binding conjugate for improved toxicity profile. Citation Format: Hui Li, Yuntao Song, Haiping Zhou, Chuan Liao, Meng Xu, Chuang Li. Modulating the release rate of polyethylene glycol (PEG) polymers from interleukin-2 (IL-2) PEG conjugates to optimize anti-tumor efficacy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4508.

Efficacy and Safety of Lebrikizumab, a High-Affinity Interleukin 13 Inhibitor, in Adults With Moderate to Severe Atopic Dermatitis

Interleukin 13 (IL-13) is a central pathogenic mediator driving multiple features of atopic dermatitis (AD) pathophysiology. To evaluate the efficacy and safety of lebrikizumab, a novel, high-affinity, monoclonal antibody targeting IL-13 that selectively prevents formation of the IL-13Rα1/IL-4Rα heterodimer receptor signaling complex, in adults with moderate to severe AD. A phase 2b, double-blind, placebo-controlled, dose-ranging randomized clinical trial of lebrikizumab injections every 4 weeks or every 2 weeks was conducted from January 23, 2018, to May 23, 2019, at 57 US centers. Participants were adults 18 years or older with moderate to severe AD. Patients were randomized 2:3:3:3 to placebo every 2 weeks or to subcutaneous injections of lebrikizumab at the following doses: 125 mg every 4 weeks (250-mg loading dose [LD]), 250 mg every 4 weeks (500-mg LD), or 250 mg every 2 weeks (500-mg LD at baseline and week 2). The primary end point was percentage change in the Eczema Area and Severity Index (EASI) (baseline to week 16). Secondary end points for week 16 included proportion of patients achieving Investigator's Global Assessment score of 0 or 1 (IGA 0/1); EASI improvement of at least 50%, 75%, or 90% from baseline; percentage change in the pruritus numeric rating scale (NRS) score; and pruritus NRS score improvement of at least 4 points. Safety assessments included treatment-emergent adverse events. A total of 280 patients (mean [SD] age, 39.3 [17.5] years; 166 [59.3%] female) were randomized to placebo (n = 52) or to lebrikizumab at doses of 125 mg every 4 weeks (n = 73), 250 mg every 4 weeks (n = 80), or 250 mg every 2 weeks (n = 75). Compared with placebo (EASI least squares mean [SD] percentage change, -41.1% [56.5%]), lebrikizumab groups showed dose-dependent, statistically significant improvement in the primary end point vs placebo at week 16: 125 mg every 4 weeks (-62.3% [37.3%], P = .02), 250 mg every 4 weeks (-69.2% [38.3%], P = .002), and 250 mg every 2 weeks (-72.1% [37.2%], P < .001). Differences vs placebo-treated patients (2 of 44 [4.5%]) in pruritus NRS improvement of at least 4 points were seen as early as day 2 in the high-dose lebrikizumab group (9 of 59 [15.3%]). Treatment-emergent adverse events were reported in 24 of 52 placebo patients (46.2%) and in lebrikizumab patients as follows: 42 of 73 (57.5%) for 125 mg every 4 weeks, 39 of 80 (48.8%) for 250 mg every 4 weeks, and 46 of 75 (61.3%) for 250 mg every 2 weeks; most were mild to moderate and did not lead to discontinuation. Low rates of injection-site reactions (1 of 52 [1.9%] in the placebo group vs 13 of 228 [5.7%] in all lebrikizumab groups), herpesvirus infections (2 [3.8%] vs 8 [3.5%]), and conjunctivitis (0% vs 6 [2.6%]) were reported. During 16 weeks of treatment, lebrikizumab provided rapid, dose-dependent efficacy across a broad range of clinical manifestations in adult patients with moderate to severe AD and demonstrated a favorable safety profile. These data support the central role of IL-13 in AD pathophysiology. If these findings replicate in phase 3 studies, lebrikizumab may meaningfully advance the standard of care for moderate to severe AD. ClinicalTrials.gov Identifier: NCT03443024.

Regulatory T Cells in the Tumor Microenvironment.

Regulatory T cells (Tregs) are an immunosuppressive subpopulation of CD4+ T cells that are endowed with potent suppressive activity and function to limit immune activation and maintain homeostasis. These cells are identified by the hallmark transcription factor FOXP3 and the high-affinity interleukin-2 (IL-2) receptor chain CD25. Tregs can be recruited to and persist within the tumor microenvironment (TME), acting as a potent barrier to effective antitumor immunity. This chapter will discuss [i] the history and hallmarks of Tregs; [ii] the recruitment, development, and persistence of Tregs within the TME; [iii] Treg function within TME; asnd [iv] the therapeutic targeting of Tregs in the clinic. This chapter will conclude with a discussion of likely trends and future directions.

Blocking CD30 on T Cells by a Dual Specific CAR for CD30 and Colon Cancer Antigens Improves the CAR T Cell Response against CD30- Tumors.

Chimeric antigen receptor (CAR)-engineered Tcells are efficacious in controlling advanced leukemia and lymphoma, however, they fail in the treatment of solid cancer, which is thought to be due to insufficient Tcell activation. We revealed that the immune response of CAR Tcells with specificity for carcinoembryonic antigen (CEA) was more efficacious against CEA+ cancer cells when simultaneously incubated with an anti-CD30 immunotoxin or anti-CD30 CAR Tcells, although the targeted cancer cells lack CD30. The same effect was achieved when the anti-CD30 single-chain variable fragment (scFv) was integrated into the extracellular domain of the anti-CEA CAR. Improvement in Tcell activation was due to interfering with the Tcell CD30-CD30L interaction by the antagonistic anti-CD30 scFv HRS3; an agonistic anti-CD30 scFv or targeting the high-affinity interleukin-2 (IL-2) receptor was not effective. Tcells with the anti-CD30/CEA CAR showed superior immunity against established CEA+ CD30- tumors in a mouse model. The concept is broadly applicable since anti-CD30/TAG72 CAR Tcells also showed improved elimination of TAG72+ CD30- cancer cells. Taken together, targeting CD30 on CAR Tcells by the HRS3 scFv within the anti-tumor CAR improves the redirected immune response against solid tumors.

Daclizumab: Mechanisms of Action, Therapeutic Efficacy, Adverse Events and Its Uncovering the Potential Role of Innate Immune System Recruitment as a Treatment Strategy for Relapsing Multiple Sclerosis.

Daclizumab (DAC) is a humanized, monoclonal antibody that blocks CD25, a critical element of the high-affinity interleukin-2 receptor (IL-2R). DAC HYP blockade of CD25 inhibits effector T cell activation, regulatory T cell expansion and survival, and activation-induced T-cell apoptosis. Because CD25 blockade reduces IL-2 consumption by effector T cells, it increases IL-2 bioavailability allowing for greater interaction with the intermediate-affinity IL-2R, and therefore drives the expansion of CD56bright natural killer (NK) cells. Furthermore, there appears to be a direct correlation between CD56bright NK cell expansion and DAC HYP efficacy in reducing relapses and MRI evidence of disease activity in patients with RMS in phase II and phase III double-blind, placebo- and active comparator-controlled trials. Therapeutic efficacy was maintained during open-label extension studies. However, treatment was associated with an increased risk of rare adverse events, including cutaneous inflammation, autoimmune hepatitis, central nervous system Drug Reaction with Eosinophilia Systemic Symptoms (DRESS) syndrome, and autoimmune Glial Fibrillary Acidic Protein (GFAP) alpha immunoglobulin-associated encephalitis. As a result, DAC HYP was removed from clinical use in 2018. The lingering importance of DAC is that its use led to a deeper understanding of the underappreciated role of innate immunity in the potential treatment of autoimmune disease.

Skin Lesions in a Daclizumab-treated Patient with Multiple Sclerosis

Abstract Background: Daclizumab is a humanized monoclonal antibody against the D-subunit (CD25) of the high-affinity interleukin (IL)–2 receptor, used for the treatment of relapsing-remitting multiple sclerosis with a large spectrum of cutaneous adverse reactions. Case presentation: We present the case of a middle-aged man treated with daclizumab for multiple sclerosis, who developed skin reactions difficult to evaluate. A 4 mm punch-biopsy was taken from the plantar area. Histological examination of the biopsy revealed hyperkeratosis and acanthosis but no parakeratosis, while a discrete inflammatory infiltrate was noticed around vessels in the dermis. Treatment with fluconazole 50 mg/day for 10 days, moisturizers, and grade I topical steroids was followed by slight improvement of the clinical picture. Treatment with daclizumab was not discontinued. Conclusion: The clinical efficacy and side effects of daclizumab have to be reported and confirmed in clinical practice in the following years. Any clinical report can contribute to validate the efficacy and risk of the drug’s administration. Any type of adverse skin reaction must be reported for clarifying the diagnosis.

Severe meningo-/encephalitis after daclizumab therapy for multiple sclerosis

Background: Daclizumab is a monoclonal antibody that binds the high-affinity interleukin-2 receptor and was approved for the treatment of relapsing multiple sclerosis. Due to severe inflammatory brain disorders, the approval was suspended in March 2018. Objective and Methods: This retrospective cohort study summarizes clinical, laboratory, radiological, and histological findings of seven patients who developed meningo-/encephalitis after daclizumab therapy. Results: Patients presented with encephalitis and/or meningitis and suffered from systemic symptoms such as fever (5/7), exanthema (5/7), or gastrointestinal symptoms (4/7). Secondary autoimmune diseases developed. Blood analysis revealed an increase in eosinophils (5/7). Six patients fulfilled the diagnostic criteria for a drug reaction with eosinophilia and systemic symptoms (DRESS). Magnetic resonance imaging (MRI) showed multiple contrast-enhancing lesions, and enhancement of the ependyma (6/7), meninges (5/7), cranial or spinal nerves (2/7), and a vasculitic pattern (3/7). Histology revealed a pronounced inflammatory infiltrate consisting of lymphocytes, plasma cells and eosinophils, and densely infiltrated vessels. Most patients showed an insufficient therapeutic response and a high disability at last follow-up (median Expanded Disability Status Scale (EDSS) 8). Two patients died. Conclusion: Meningoencephalitis and DRESS may occur with daclizumab therapy. This potential lethal side effect is characterized by a dysregulated immune response. Our findings underline the importance of postmarketing drug surveillance.

Daclizumab Therapy for Multiple Sclerosis.

Daclizumab is a humanized monoclonal antibody that prevents formation of high-affinity interleukin (IL)-2 receptor (IL-2R). Because activated T cells up-regulate high-affinity IL-2R and IL-2 is used to grow activated T cells in vitro, daclizumab was envisioned to selectively inhibit activated T cells. However, the mechanism of action (MOA) of daclizumab is surprisingly broad and it includes many unanticipated effects on innate immunity. Specifically, daclizumab modulates the development of innate lymphoid cells, leading to expansion of immunoregulatory CD56bright natural killer (NK) cells. Activated CD56bright NK cells migrate to the intrathecal compartment in multiple sclerosis (MS) and regulate autoreactive T cells via cytotoxicity. Finally, daclizumab also restricts initial steps of T-cell activation by blocking trans-presentation of IL-2 by dendritic cells to antigen-specific T cells. In conclusion, daclizumab has complex immunomodulatory effects with resultant inhibition of central nervous system inflammation in MS.

Pharmacokinetic drug evaluation of daclizumab for the treatment of relapsing-remitting multiple sclerosis

ABSTRACT Introduction: Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system. Despite the availability of several disease-modifying therapies for relapsing MS, there is a need for highly efficacious targeted therapy with a favorable benefit–risk profile and a high level of treatment adherence. Daclizumab is a humanized monoclonal antibody directed against CD25, the α subunit of the high-affinity interleukin 2 (IL-2) receptor, that reversibly modulates IL-2 signaling. Areas covered: Daclizumab blocks the activation and expansion of autoreactive T cells that plays a role in the immune pathogenesis of MS. As its modulatory effects on the immune system, daclizumab’s potential for use in MS was tested extensively showing a high efficacy in reducing relapse rate, disability progression and the number and volume of gadolinium-enhancing lesions on brain magnetic resonance imaging. Moreover, phase II and III trials showed a favorable pharmacokinetic (PK) profile with slow clearance, linear pharmacokinetics at doses above 100 mg and high subcutaneous bioavailability, not influenced by age, sex or other clinical parameters. Expert opinion: Among the new emerging drugs for MS, daclizumab also, thanks to a favorable PK profile, may represent an interesting and promising therapeutic option in the wide MS therapies armamentarium.

Daclizumab for the treatment of adults with relapsing forms of multiple sclerosis

ABSTRACTIntroduction: The goal of the article is to review the mechanism of action and the use of daclizumab, a humanized monoclonal antibody (mAb) against the alpha subunit of the high affinity interleukin-2 (IL-2) receptor, in the treatment of Multiple Sclerosis (MS).Areas covered: PubMed was searched for the terms ‘daclizumab’ and ‘multiple sclerosis’. The mechanisms of action, pharmacokinetics and pharmacodynamics, major studies, side effects and drug interactions of daclizumab in MS are discussed.Expert commentary: Monthly daclizumab-beta [DAC-beta, formerly daclizumab high yield process (DAC HYP), approved as ZINBRYTA®, which has a different form and structure than an earlier form of daclizumab], is an effective and convenient treatment option for patients with relapsing forms of MS who have failed other treatment, or as a first-line option in highly active MS patients. IL-2 signaling modulation by daclizumab constitutes a novel mechanism of action which may also underlie the adverse and serious adverse events and risk profile of the drug that requires appropriate patient selection, monitoring and risk-mitigation programs.

Daclizumab: Development, Clinical Trials, and Practical Aspects of Use in Multiple Sclerosis.

Daclizumab is a humanized monoclonal antibody directed towards CD25, the alpha subunit of the high-affinity interleukin (IL)-2 receptor. Daclizumab exerts its effects via multiple mechanisms, including reduction of IL-2-mediated lymphocyte activation and upregulation of CD56-bright natural killer cells. Intravenous daclizumab (Zenapax™) was initially approved for prevention of rejection in renal transplant. In subsequent early testing, followed by larger-scale phase II and phase III trials, both intravenous and subcutaneous daclizumab have demonstrated clinical efficacy in the treatment of multiple sclerosis. The subcutaneous daclizumab prepared by high-yield process was utilized in the advanced phase II and phase III trials (SELECT and DECIDE). High-yield process daclizumab is now approved by the US Food and Drug Administration for relapsing-remitting multiple sclerosis, and is now formally termed daclizumab beta (DAC-beta; Zinbryta™). In this review, the early development of anti-IL-2 receptor alpha monoclonal antibodies and the properties of IL-2 and its receptor are discussed, and diverse mechanisms of action for daclizumab are presented. Results of the CHOICE, SELECT, and DECIDE clinical trials are discussed in detail. Adverse events observed in clinical trials included cutaneous reactions, liver enzyme elevations, infections, and autoimmune phenomena. DAC-beta is a monthly, patient-administered subcutaneous injection that requires enrollment in a safety monitoring (REMS) program for monthly liver function testing. Prescribers should be aware of the potential adverse events, as early recognition and management is important, particularly in cutaneous and hepatic reactions. Continued clinical experience with DAC-beta, including observations from the REMS program, will define its place in the armamentarium of immunotherapeutics for relapsing-remitting multiple sclerosis.

Daclizumab: A Review in Relapsing Multiple Sclerosis.

Daclizumab (Zinbryta®; previously known as daclizumab high-yield process) is a therapeutic monoclonal antibody that has recently been approved for the treatment of relapsing forms of multiple sclerosis (MS) in adults. Daclizumab is a humanized IgG1 monoclonal antibody directed against CD25, the alpha subunit of the high-affinity interleukin-2 receptor. As demonstrated in the phaseIII DECIDE trial, once-monthly subcutaneous daclizumab was superior to once-weekly intramuscular interferon (IFN) β-1a in reducing the clinical relapse rate and radiological measures of disease in patients with relapsing-remitting MS. In addition, daclizumab has demonstrated efficacy in reducing disability progression and in improving health-related quality of life in patients with relapsing MS. Ongoing open-label clinical trials indicate that daclizumab's efficacy is maintained in the longer term (3years or more). Daclizumab appears to be generally well tolerated, with adverse events of interest (including hepatic, infectious and cutaneous events) generally manageable with regular monitoring and/or standard therapies. The place of daclizumab in MS treatment remains to be fully determined. However, based on available evidence, daclizumab provides a useful alternative option to other currently available disease-modifying therapies in the treatment of relapsing MS.

Therapeutic efficacy of monthly subcutaneous injection of daclizumab in relapsing multiple sclerosis.

Despite the availability of multiple disease-modifying therapies for relapsing multiple sclerosis (MS), there remains a need for highly efficacious targeted therapy with a favorable benefit–risk profile and attributes that encourage a high level of treatment adherence. Daclizumab is a humanized monoclonal antibody directed against CD25, the α subunit of the high-affinity interleukin 2 (IL-2) receptor, that reversibly modulates IL-2 signaling. Daclizumab treatment leads to antagonism of proinflammatory, activated T lymphocyte function and expansion of immunoregulatory CD56bright natural killer cells, and has the potential to, at least in part, rectify the imbalance between immune tolerance and autoimmunity in relapsing MS. The clinical pharmacology, efficacy, and safety of subcutaneous daclizumab have been evaluated extensively in a large clinical study program. In pivotal studies, daclizumab demonstrated superior efficacy in reducing clinical and radiologic measures of MS disease activity compared with placebo or intramuscular interferon beta-1a, a standard-of-care therapy for relapsing MS. The risk of hepatic disorders, cutaneous events, and infections was modestly increased. The monthly subcutaneous self-injection dosing regimen of daclizumab may be advantageous in maintaining patient adherence to treatment, which is important for optimal outcomes with MS disease-modifying therapy. Daclizumab has been approved in the US and in the European Union and represents an effective new treatment option for patients with relapsing forms of MS, and is currently under review by other regulatory agencies.

Association between the IL2RA polymorphism and type 1 diabetes risk: Family based association study

As part of an ongoing search for genes associated with type 1 diabetes (T1D), a common autoimmune disease, we tested the candidate genes; IL2RA (CD25), which encodes a subunit (IL2Rα) of the high-affinity interleukin-2 (IL2) receptor complex and IL2RB, encodes a subunit (IL-2Rβ). In order to underline the role of these genes involved in control of T-cell immune responses and autoimmunity, we investigated, using the Sequenom MassARRAY platform, thirty five variants from two genes: 25 SNPs from IL2RA gene and ten SNPs from IL2RB gene in 59 T1D Tunisian families.Using the Family-based association test (FBAT), which uses generalized score statistics to perform a variety of transmission disequilibrium tests (TDT), we performed a statistical analysis under the default model (additive) in order to evaluate allelic and genotypic transmission from parent to affect offspring. We observed an overtransmission of alleles from parents to affected child at tow variants of IL2RA: (rs2104286, allele T, P=0.027; z=2.209; rs791589, allele G, P=0.043; z=2.021). When haplotypes were constructed, we also identified an overtransmission of TTCCA haplotype (P=0.017) derived from the haplotype analysis across the five IL2RA markers (rs706778 rs2104286/rs7072793/rs7073236/rs11597367), while CCTTA haplotype was undertransmitted to affect children (P=0.0124).These findings confirm the role of IL2RA involved in the T cell regulation pathway in the development of T1D in Tunisian families. The association of IL2RA/CD25 with a fifth autoimmune disease suggests that this gene appears to play a vital role in immune regulation and function as well as predisposition to autoimmunity in general. Further investigation of the gene using both genetic and functional approaches is required.

Pharmacokinetics of daclizumab high-yield process with repeated administration of the clinical subcutaneous regimen in patients with relapsing-remitting multiple sclerosis.

BackgroundDaclizumab high-yield process (DAC HYP), a humanized immunoglobulin G1 monoclonal antibody specific for the α subunit (CD25) of the high-affinity interleukin-2 receptor, has demonstrated efficacy for treatment of relapsing forms of multiple sclerosis in Phase II and III clinical trials.ObjectiveTo characterize the pharmacokinetics (PK) of DAC HYP following repeated administration of the 150 mg subcutaneous (SC) dose every 4 weeks (q4wk), the proposed clinical regimen in patients with relapsing-remitting multiple sclerosis (RRMS).MethodsTwenty-six patients with RRMS received DAC HYP 150 mg SC q4wk for a total of six doses. Serial PK blood samples were collected over the first and last dosing intervals and trough PK samples were collected between these doses. Blood samples for immunogenicity assessment were collected throughout the study. Serum DAC HYP levels and anti-DAC HYP antibodies were characterized using validated immunoassays. PK parameters were estimated using noncompartmental analysis.ResultsDAC HYP showed slow SC absorption with a median time to reach maximum observed concentration (Cmax) value of ~1 week. Steady state was reached by the fourth injection. At steady state, DAC HYP mean serum Cmax, minimum observed concentration (Cmin), and area under the concentration–time curve within a dosing interval (AUCtau) values were 29.1 µg/mL, 14.9 µg/mL, and 638 µg · day/mL, respectively, with intersubject variability of 35%–40%. The AUC accumulation ratio was ~2.5 at steady state. DAC HYP had a long elimination half-life of ~22 days and low apparent clearance (0.274 L/day). Nine patients tested positive for anti-DAC HYP antibodies, with no impact on DAC HYP clearance in this limited data set.ConclusionThe PK of DAC HYP in patients with RRMS are consistent with those previously reported in healthy volunteers. The half-life of ~3 weeks and the low fluctuations in peak and trough concentrations of serum DAC HYP support the once-monthly SC dosing regimen.

IL-2 Induces Selective Activation of Helios-Positive Regulatory T Cells and CD56bright NK Cells in Vitro and in Patients with Chronic Gvhd Receiving Low-Dose IL-2 Therapy

▪Introduction: CD4+ FoxP3+ CD25+ regulatory T cells (Treg) play a central role in the maintenance of immune tolerance and prevention of chronic graft-versus-host disease (cGVHD) after allogeneic stem cell transplantation (SCT). Treg constitutively express high-affinity interleukin-2 (IL-2) receptors and murine models have established that IL-2 is a critical homeostatic regulator of Treg in vivo. We previously reported that daily administration of low-dose IL-2 in patients with cGVHD induces selective expansion of Treg and NK cells and results in clinical improvement in approximately 50% of patients. However, the mechanisms responsible for these selective effects and the influence of IL-2 therapy on other lymphocytes have not been established due to the limited resolution of traditional cell analytic methods such as flow cytometry.Methods: Single cell mass cytometry (CyTOF) with a panel of 33 markers was used to simultaneously examine the phenotypic and functional effects of low-dose IL-2 on lymphocyte populations in vitro and in vivo. The analytic panel included 22 cell surface markers to identify distinct T, B and NK cell subsets and 11 intracellular markers to measure functional status and activation of specific signaling pathways. viSNE, a cytometry analysis tool, was used to visualize high-dimensional cytometry data on a two-dimensional map.Results: In unstimulated lymphocytes from healthy donors, constitutive expression of CD25 (IL-2Ra) at high levels was restricted to Treg and CD56bright NK cells. Central memory (CM) and effector memory (EM) subsets of conventional CD4 T cells (Tcon) and CM CD8 T cells expressed low levels of CD25. Within the Treg population, the highest expression of CD25 was closely associated with expression of Helios transcription factor. Helios+ Treg also express higher levels of FoxP3, HLA-DR and CD95 and lower levels of BCL2 compared to Helios- Treg. To examine responses to IL-2, we stimulated peripheral blood mononuclear cells (PBMC) from healthy donors with IL-2 for 15 min in vitro (Figure 1). At low IL-2 concentrations (1 to 10 IU/ml), pSTAT5 was preferentially activated in Treg. Notably, pSTAT5 activation was more robust in memory Treg than naïve Treg and in Helios+ Treg than Helios- Treg. In addition, we observed activation of pSTAT5 in CD56bright NK cells at low concentrations of IL-2 (10 IU/ml). Higher IL-2 concentrations (100-1000 IU/ml) were required to activate pSTAT5 in Tcon, CD8 T cells and CD56dim NK cells. At high IL-2 concentrations, pSTAT5 was activated in all Treg, NK, Tcon and CD8 subsets. To examine the response to IL-2 in vivo, we examined PBMC from 14 patients with chronic GVHD receiving daily low-dose IL-2 using the same CyTOF panel of markers. Without additional in vitro stimulation, pSTAT5 expression was increased preferentially in Helios+ Treg. Peak pSTAT5 expression occurred 1 week after starting IL-2 and decreased with continued IL-2 therapy. Similarly, increased expression of FoxP3, CD25, HLA-DR and Ki67 occurred primarily in Helios+ Treg with peak expression at 1 week. At later time points during IL-2 therapy, changes in Treg included increased expression of CD95, CTLA4, PD-1, BIM and BCL2. Although there was no activation of pSTAT5 in CD4 Tcon and CD8 T cells, expression of PD-1 increased in effector memory subsets of Tcon and CD8 T cells 1 week after starting IL-2 therapy. Selective expansion of CD56bright NK cells was also noted, with peak activation at 1 week. No other changes were noted in Tcon, CD8 T cells and B cells. All changes observed during IL-2 therapy returned to baseline levels 4 weeks after treatment was stopped. However, examination of PBMC from 8 patients who received continuous daily low-dose IL-2 therapy for approximately 1 year showed that all of the changes noted above persisted during extended therapy.Conclusion: Comprehensive analysis of T, B and NK cells from healthy donors revealed that low concentrations of IL-2 result in selective activation of Helios+ Treg and CD56bright NK cells. Higher concentrations of IL-2 are required for activation of CD4 Tcon, CD8 T cells and CD56dim NK cells. Identical populations are activated in patients with cGVHD receiving daily low-dose IL-2 and these functional effects persist during extended IL-2 therapy. Although the function of Helios transcription factor is not well defined, Helios expression identifies those Treg most primed to respond to low concentrations of IL-2 in vitro and in vivo. [Display omitted] DisclosuresArmand:Infinity Pharmaceuticals: Consultancy; Merck: Consultancy, Research Funding; Bristol-Myers Squibb: Research Funding. Antin:Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Gentium S.p.A.: Membership on an entity's Board of Directors or advisory committees. Soiffer:Gentium SpA/Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees.

Tregalizumab (BT-061) increases regulatory T cell function. Boosting regulatory T-cell function with the humanized CD4-specific humanized monoclonal antibody Tregalizumab (BT-061).

Regulatory T cells (Tregs) represent a subset of CD4+ T cells that express the forkhead box protein 3 factor (FOXP3) in their nuclei1 and the high-affinity interleukin 2 (IL-2) receptor CD25 on their cell surface as they are dependent on IL-2 for their homeostasis.2 Since their discovery 20 years ago,3 Tregs have proven to be indispensable for maintaining immunological self-tolerance. Indeed, Treg depletion results in a wide spectrum of autoimmune manifestations,3 whereas mutations of FOXP3 lead to fatal autoimmunity both in mice (scurfy mice) and humans (Immune dysfunction, polyendocrinopathy, enteropathy, X-linked syndrome).1 Further, restoring the T-cell balance in favor of Tregs has allowed the control of autoimmunity in a number of animal rheumatologic models.4