A safety and pharmacodynamics study of temelimab, an antipathogenic human endogenous retrovirus type W envelope monoclonal antibody, in patients with type 1 diabetes.

AIM: To report the first study of temelimab, a monoclonal antibody neutralizing the pathogenic human endogenous retrovirus type W envelope, in patients with type 1 diabetes (T1D). MATERIALS AND METHODS: This double-blind, placebo-controlled, randomized clinical trial recruited adult patients with T1D within 4 years postdiagnosis and remaining C-peptide secretion. Sixty-four patients were randomized (2:1) to monthly temelimab 6 mg/kg or placebo during 24 weeks followed by a 24-week, open-label extension, during which all patients received temelimab. The primary objective was the safety and tolerability of temelimab. The secondary objective was to assess the pharmacodynamics response such as C-peptide levels, insulin use, HbA1c, hypoglycaemia and autoantibodies. RESULTS: Temelimab was well tolerated without any group difference in the frequency or severity of adverse events. Concerning exploratory endpoints, there was no difference in the levels of C-peptide, insulin use or HbA1c between treatment groups at weeks 24 and 48. The frequency of hypoglycaemia events was reduced with temelimab (P = 0.0004) at week 24 and the level of anti-insulin antibodies was lower with temelimab (P < 0.01); the other autoantibodies did not differ between groups. CONCLUSIONS: Temelimab appeared safe in patients with T1D. Pharmacodynamics signals (hypoglycaemia and anti-insulin antibodies) under temelimab were observed. Markers of ß-cell functions were not modified by treatment. These results need to be further explored in younger patients with T1D with earlier disease onset.

A High-dose Pharmacokinetic Study of a New IgG4 Monoclonal Antibody Temelimab/GNbAC1 Antagonist of an Endogenous Retroviral Protein pHERV-W Env.

PURPOSE: Temelimab/GNbAC1 is a humanized immunoglobulin G4 monoclonal antibody antagonist of the human endogenous retrovirus W envelope protein, which is associated with multiple sclerosis (MS) pathophysiology and possibly with other autoimmune disorders. Human endogenous retrovirus W envelope protein is expressed in the central nervous system of patients with MS, and sufficient amount of temelimab must reach the target. The safety of very high dosages of temelimab should be tested to support further clinical trials in MS. METHODS: This randomized, placebo-controlled, dose-escalation study evaluated the safety and pharmacokinetic profile of temelimab in 24 healthy volunteers after a single intravenous infusion at doses of 36, 60, 85, and 110 mg/kg administered sequentially. FINDINGS: Temelimab was well tolerated, with no particular adverse drug reactions at any dose. The maximal dose of 110 mg/kg could be administered, and no antidrug antibodies were induced. After administration of 36-110 mg/kg, mean temelimab Cmax increased from 859 to 2450 µg/mL, and AUC values increased from 319,900 to 1,030,000 µg·h/mL. There was an approximate dose-proportional increase in exposure, similar to observations at lower doses. IMPLICATIONS: The favorable data in terms of safety and pharmacokinetic variables support temelimab use at high doses in future MS trials to optimally neutralize the temelimab target in the central nervous system. ClinicalTrials.gov identifier: NCT03574428.

A new therapeutic approach for type 1 diabetes: Rationale for GNbAC1, an anti-HERV-W-Env monoclonal antibody.

We describe a newly identified therapeutic target for type 1 diabetes (T1D): an envelope protein of endogenous retroviral origin, human endogenous retrovirus W envelope (HERV-W-Env). HERV-W-Env was found to be detected in the blood of ~60% of patients with T1D and is expressed in acinar pancreatic cells of 75% of patients with T1D at post mortem examination. Preclinical experiments showed that this protein displays direct cytotoxicity on human ß-islet cells. In vivo HERV-W-Env impairs the insulin and glucose metabolism in transgenic mice expressing HERV-W-Env. GNbAC1, an IgG4 monoclonal antibody, has been developed to specifically target HERV-W-Env and to neutralize the effect of HERV-W-Env in vitro and in vivo. GNbAC1 is currently in clinical development for multiple sclerosis and > 300 subjects have been administered with GNbAC1 so far. GNbAC1 is now being tested in T1D in the RAINBOW-T1D study, which is a randomized placebo-controlled study with the objective of showing the safety and pharmacodynamic response of GNbAC1 in patients who have had T1D with a maximum of 4 years' duration. GNbAC1 is being tested vs placebo at the dose of 6 mg/kg in 60 patients during six repeated administrations for 6 months; a 6-month open-label extension will follow. The primary endpoint is to assess safety, and secondary endpoints are the pharmacodynamic responses to GNbAC1. GNbAC1 targeting HERV-W-Env is currently in clinical development in T1D, with the first safety and pharmacodynamic study. If the study results are positive, this may open the door to the development of an innovative non-immunomodulatory disease-modifying treatment for T1D.