REGN1908/1909 prevented cat allergen-induced early asthmatic responses in an environmental exposure unit.

BACKGROUND: The dominant allergen in cat dander, Felis domesticus allergen 1 (Fel d 1), is a persistent trigger for allergic rhinitis and asthma symptoms. OBJECTIVE: We evaluated the efficacy of Fel d 1 monoclonal antibodies (REGN1908/1909) in preventing cat allergen-induced early asthmatic responses (EARs) in cat-allergic patients with mild asthma. METHODS: Patients were randomized to single-dose REGN1908/1909 600 mg (n = 29) or placebo (n = 27). The FEV1 was measured for up to 4 hours in a cat allergen environmental exposure unit up to 85 days after dosing. Assessments included between-group differences in change from baseline in FEV1 area under the curve (AUC; 0-2 hours) and incidence of EAR (FEV1 reduction ≥20%). TRIAL REGISTRATION: NCT03838731. RESULTS: Single-dose REGN1908/1909 significantly prevented reductions in FEV1 on days 8, 29, 57, and 85. Most REGN1908/1909 patients did not have an EAR by 4 hours (the last time point tested). In contrast, placebo-treated patients experienced a ≥20% mean FEV1 reduction on days 8, 29, 57, and 85 after dosing, with most experiencing an EAR within 1 hour. REGN1908/1909-treated patients tolerated 3-fold higher allergen quantities (P < .05 at all time points) versus placebo. REGN1908/1909 substantially reduced skin test reactivity to cat allergen versus placebo at all time points tested (nominal P < .001). REGN1908/1909 was generally well tolerated; no serious adverse events or deaths were reported. CONCLUSION: Single-dose REGN1908/1909 significantly prevented reductions in FEV1 in cat-allergic patients with mild asthma on cat allergen environmental exposure unit exposure at 8 days and up to 85 days after dose.

Novel antibody cocktail targeting Bet v 1 rapidly and sustainably treats birch allergy symptoms in a phase 1 study.

BACKGROUND: The efficacy of an allergen-specific IgG cocktail to treat cat allergy suggests that allergen-specific IgG may be a major protective mechanism elicited by allergen immunotherapy. OBJECTIVES: Extending these findings, we tested a Bet v 1-specific antibody cocktail in birch-allergic subjects. METHODS: This was a phase 1, randomized, double-blind, study with 2 parts. Part A administered ascending doses of the Bet v 1-specific antibody cocktail REGN5713/14/15 (150-900 mg) in 32 healthy adults. Part B administered a single subcutaneous 900-mg dose or placebo in 64 birch-allergic subjects. Total nasal symptom score response to titrated birch extract nasal allergen challenge and skin prick test (SPT) with birch and alder allergen were assessed at screening and days 8, 29, 57, and 113 (SPT only); basophil activation tests (n = 26) were conducted. RESULTS: Single-dose REGN5713/14/15 significantly reduced total nasal symptom score following birch nasal allergen challenge relative to baseline. Differences in total nasal symptom score areas under the curve (0-1 hour) for subjects treated with REGN5713/14/15 versus those given placebo (day 8: -1.17, P = .001; day 29: -1.18, P = .001; day 57: -0.85, P = .024) and titration SPT with birch difference in area under the curve of mean wheal diameters for subjects treated with REGN5713/14/15 versus placebo (all P < .001) were sustained for ≥2 months; similar results were observed with alder SPT. REGN5713/14/15 was well tolerated. Basophil responsiveness to birch-related allergens was significantly decreased in subjects treated with REGN5713/14/15 versus those given placebo on days 8, 57, and 113 (all P < .01). CONCLUSIONS: Single-dose REGN5713/14/15 was well tolerated and provided a rapid (1 week) and durable (2 months) reduction in allergic symptoms after birch allergen nasal allergen challenge, potentially offering a new paradigm for the treatment of birch allergy symptoms.

Biological Function and Immunotherapy Utilizing Phosphatidylserine-based Nanoparticles.

Phosphatidylserine (PS) is a naturally occurring anionic phospholipid that is primarily located in the inner leaflet of eukaryotic cell membranes. The role of PS during apoptosis is one of the most studied biological functions of PS. Externalization of PS during apoptosis mediates an "eat me" signal for phagocytic uptake, leading to clearance of apoptotic cells and thus maintain self-tolerance by immunological ignorance. However, an emerging view is that PS exposure-mediated cellular uptake is not an immunologically silent event, but rather promoting an active tolerance towards self and foreign proteins. This biological property of PS has been exploited by parasites and viruses in order to evade immune surveillance of the host immune system. Further, this novel immune regulatory property of PS that results in tolerance induction can be harnessed for clinical applications, such as to treat autoimmune conditions and to reduce immunogenicity of therapeutic proteins. This review attempts to provide an overview of the biological functions of PS in the immune response and its potential therapeutic applications.

Evinacumab: Mechanism of action, clinical, and translational science.

Homozygous familial hypercholesterolemia (HoFH) is a rare and serious genetic condition characterized by premature cardiovascular disease due to severely elevated low-density lipoprotein cholesterol (LDL-C). HoFH primarily results from loss-of-function (LOF) mutations in the LDL receptor (LDLR), reducing LDL-C clearance such that patients experience severe hypercholesterolemia, exacerbating the risk of developing cardiovascular events. Treatment options such as statins, lomitapide, ezetimibe, proprotein convertase subtilisin/kexin type 9 inhibitors, and apheresis help lower LDL-C; however, many patients with HoFH still fail to reach their target LDL-C levels and many of these lipid-lowering therapies are not indicated for pediatric use. Angiopoietin-like protein 3 (ANGPTL3) has been identified as a target to treat elevated LDL-C by acting as a natural inhibitor of lipoprotein lipase (LPL) and endothelial lipase (EL), enzymes involved in the hydrolysis of the triglyceride and phospholipid content of very low-density lipoproteins. Persons heterozygous for LOF mutations in ANGPTL3 were reported to have lower LDL-C than non-carriers and lower risk of coronary artery disease. Evinacumab is a first-in-class human monoclonal antibody that specifically binds to ANGPTL3 to prevent its inhibition of LPL and EL. In clinical trials, a 15 mg/kg intravenous dose every 4 weeks has shown a mean percent change from baseline in LDL-C of ~50% in adult, adolescent, and pediatric patients with HoFH. This mini review article describes the mechanism of action of evinacumab, evinacumab population PK and PD modeling, and clinical development history of evinacumab for the treatment of HoFH.

Dupilumab in Adults With Moderate to Severe Atopic Dermatitis: A 5-Year Open-Label Extension Study.

Importance: Moderate to severe atopic dermatitis (AD) is a chronic inflammatory skin disease that often requires continuous long-term systemic management. Long-term safety and efficacy data for treatment options are critically important. Objective: To assess the safety and efficacy of dupilumab treatment for up to 5 years in adults with moderate to severe AD. Design, Setting, and Participants: The 5-year LIBERTY AD open-label extension study was conducted from September 2013 to June 2022 at 550 sites in 28 countries. The study enrolled adult patients with moderate to severe AD who had participated in previous dupilumab clinical trials. Data were analyzed from August 2022 to February 2023. Exposures: At enrollment, patients initiated a regimen of subcutaneous dupilumab, 200 mg, weekly (400-mg loading dose). The regimen was amended in June 2014 to dupilumab, 300 mg, weekly (600-mg loading dose) based on a dose-ranging study and again in November 2019 to dupilumab, 300 mg, every 2 weeks to align with the regulatory regimen approvals. Main Outcomes and Measures: The primary end points were the incidence and rate of treatment-emergent adverse events (TEAEs). Key secondary end points included incidence and rate of serious TEAEs and adverse events of special interest, proportion of patients achieving an Investigator's Global Assessment (IGA) score of 0 or 1 (clear or almost clear), and proportion of patients with 75% or more improvement in the Eczema Area and Severity Index (EASI) from the parent study baseline. Results: A total of 2677 patients were enrolled and treated in the open-label extension study; 1611 (60.2%) were male, and the mean (SD) age was 39.2 (13.4) years. A total of 334 patients (12.5%) completed treatment up to week 260. The most common reasons for withdrawal were due to regulatory approval of dupilumab in compliance with the study protocol (810 of 1380 [58.7%]), patient withdrawal (248 of 1380 [18.0%]), and adverse events (116 of 1380 [8.4%]). Exposure-adjusted rates of TEAEs were generally stable or declined throughout the study. Common TEAEs (incidence of 5% or greater) included nasopharyngitis, worsening AD, upper respiratory tract infection, conjunctivitis, conjunctivitis allergic, headache, oral herpes, and injection-site reaction. At week 260, 220 of 326 patients (67.5%) achieved an IGA score of 0 or 1 and 288 of 324 (88.9%) achieved 75% or greater improvement in the EASI. The mean (SD) EASI score was 16.39 (14.60) at baseline and 2.75 (5.62) at end of study. Conclusions and Relevance: In this study, there was sustained safety and efficacy of continuous long-term dupilumab treatment for adults with moderate to severe AD.

Tolerogenic form of Factor VIII to prevent inhibitor development in the treatment of Hemophilia A.

BACKGROUND: The development of antidrug antibodies, also termed inhibitors, against administered factor VIII (FVIII) is one of the major complications in the clinical management of hemophilia A. Once formed, these inhibitory antibodies abrogate the activity of FVIII, resulting in loss of hemostatic efficacy and patients are subjected to increased risk of bleeding tendencies. Current treatment options after inhibitor development are expensive and ineffective in some cases. Therefore, treatment strategies that can prevent inhibitor formation is an effective approach in the management of hemophilia A. OBJECTIVES: We aimed to evaluate and discuss the use of a tolerogenic form of FVIII as an immunotherapy strategy to prevent inhibitor risk. METHODS: FVIII was associated with nanoparticles containing lysophosphatidylserine (Lyso-PS) and administered to hemophilia A mice via intravenous route. These animals then received weekly rechallenge injections with free FVIII, and plasma was collected at the end of the study to evaluate for inhibitor development. To investigate whether Lyso-PS nanoparticles influence the plasma survival of FVIII, a pharmacokinetic study following a single intravenous administration of FVIII in the presence and absence of Lyso-PS nanoparticles was performed. For dosing convenience, the tolerogenic effect of Lyso-PS nanoparticles following oral administration was also examined. RESULTS AND CONCLUSIONS: The results demonstrated that FVIII associated with Lyso-PS nanoparticles significantly reduced inhibitor development while improving plasma survival of FVIII following intravenous administration, suggesting a multifunctional FVIII form to improve clinical utility. Additionally, reduction in inhibitor formation can also be achieved using Lyso-PS nanoparticles through the user-friendly oral route of administration.

REGN1908-1909 monoclonal antibodies block Fel d 1 in cat allergic subjects: Translational pharmacokinetics and pharmacodynamics.

REGN1908-1909, a 1:1 cocktail of two fully human IgG4 monoclonal antibodies (mAbs), REGN1908 and REGN1909, is being evaluated for treatment of cat allergy. Both REGN1908 and REGN1909 bind to the dominant cat allergen, Fel d 1. Adults with cat allergy confirmed by skin prick test (SPT) were randomized to single subcutaneous administration of placebo (n = 6) or REGN1908-1909 at doses of 150 (n = 6), 300 (n = 6), or 600 mg (n = 6). Blood samples were taken at prespecified time points for pharmacokinetic (PK) analysis and exploratory evaluation of biomarkers (IgE and SPT). Safety was assessed. Drug concentration-time profiles in serum for ascending doses of REGN1908-1909 were consistent with linear PKs. Noncompartmental analysis showed that maximum concentration (Cmax ) and exposure increased proportionately with dose, with similar time to maximum concentration (Tmax ) for REGN1908 and REGN1909 (6.2 to 8.2 days across doses), and a longer terminal half-life for REGN1908 (~ 30 days) relative to REGN1909 (~ 21 days). Adverse events were not dose dependent; there were no dose-limiting toxicities. REGN1908-1909 is characterized by linear and dose-proportional kinetics of the two individual mAb components. A single 600 mg dose maintains total mAb mean concentrations in serum above the target (mean of ~ 10 mg/L) for 8-12 weeks. Maintaining this mean target concentration resulted in translational pharmacodynamic effects: maximal mast cell degranulation in a passive cutaneous anaphylaxis mouse model, and maintenance of clinical efficacy measured by Total Nasal Symptom Score in a previous proof-of-mechanism study.

Rational design of a nanoparticle platform for oral prophylactic immunotherapy to prevent immunogenicity of therapeutic proteins.

The safety and efficacy of several life-saving therapeutic proteins are compromised due to their immunogenicity. Once a sustained immune response against a protein-based therapy is established, clinical options that are safe and cost-effective become limited. Prevention of immunogenicity of therapeutic proteins prior to their initial use is critical as it is often difficult to reverse an established immune response. Here, we discuss a rational design and testing of a phosphatidylserine-containing nanoparticle platform for novel oral prophylactic reverse vaccination approach, i.e., pre-treatment of a therapeutic protein in the presence of nanoparticles to prevent immunogenicity of protein therapies.

Immunogenicity of Protein Pharmaceuticals.

Protein therapeutics have drastically changed the landscape of treatment for many diseases by providing a regimen that is highly specific and lacks many off-target toxicities. The clinical utility of many therapeutic proteins has been undermined by the potential development of unwanted immune responses against the protein, limiting their efficacy and negatively impacting its safety profile. This review attempts to provide an overview of immunogenicity of therapeutic proteins, including immune mechanisms and factors influencing immunogenicity, impact of immunogenicity, preclinical screening methods, and strategies to mitigate immunogenicity.

Lipidic Nanoparticles Comprising Phosphatidylinositol Mitigate Immunogenicity and Improve Efficacy of Recombinant Human Acid Alpha-Glucosidase in a Murine Model of Pompe Disease.

Enzyme replacement therapy with recombinant human acid α-glucosidase (rhGAA) is complicated by the formation of anti-rhGAA antibodies, a short circulating half-life, instability in the plasma, and limited uptake into target tissue. Previously, we have demonstrated that phosphatidylinositol (PI) containing liposomes can reduce the immunogenicity and extend plasma survival of factor VIII (FVIII) in a mouse model of hemophilia A. In this article, we investigate the ability of PI liposomes to be used as a delivery vehicle to overcome the issues that complicate therapy with rhGAA. In a murine model of Pompe disease, administration of PI-rhGAA mitigated the immunogenicity of rhGAA, resulting in a significantly lower formation of anti-rhGAA antibodies. PI-rhGAA also showed minimal improvements to the pharmacokinetic parameters and efficacy measures compared to free rhGAA. Overall, these data suggest that PI-rhGAA may have the potential to be a useful therapeutic option for improving the treatment of Pompe disease.

Phosphatidylserine Is Not Just a Cleanup Crew but Also a Well-Meaning Teacher.

Phosphatidylserine (PS) exposure during apoptosis leads to silent clearance of cells without adverse immune reactions to self-proteins. Given the biological functions of PS in cellular cleanup and global immunosuppression, we hypothesized that administration of PS-protein complexes would reduce immunogenicity. Here, we report that exposing Pompe disease mice to acid alpha glucosidase (rhGAA) with PS or immunosuppressant dexamethasone resulted in lower anti-rhGAA antibodies than in animals receiving rhGAA alone. However, upon rechallenge with rhGAA, only PS-rhGAA pre-exposed mice displayed a durable hyporesponsiveness even after PS administration was ceased. Thus, pre-exposure of antigens administered together with PS were not silently cleared, but the immune system acquired memory about the antigen that averted mounting of a response during rechallenge. In hemophilia A mice, PS hyporesponsiveness toward Factor VIII was reversed by administration of function-blocking antibody against the PS receptor T-cell immunoglobulin and mucin 4, implicating this receptor in PS's effect. Moreover, pre-exposure of myelin oligodendrocyte glycoprotein peptide with PS delayed the onset and reduced the severity of experimental autoimmune encephalomyelitis. These observations suggest that PS's function in apoptosis is not limited to silent antigen clearance without immune responses toward self-proteins but shows that PS reduces immune response during rechallenge to several antigens that also involves initiation of antigen tolerance.