# Design and methods of the Ixekizumab Diabetes Intervention Trial (I-DIT): protocol for a phase 2, randomised, multicentre, placebo-controlled, double-blind trial of anti-interleukin 17 as a treatment option for adults with new-onset type 1 diabetes

## TL;DR

This study tests whether blocking IL-17 can preserve insulin-producing cells in newly diagnosed type 1 diabetes patients.

## Contribution

The trial introduces a novel approach using IL-17 inhibition to potentially slow beta cell loss in early type 1 diabetes.

## Key findings

- The trial will assess changes in residual insulin secretion over 52 weeks using C-peptide measurements.
- Secondary outcomes include glucose control metrics and patient-reported outcomes over multiple time points.
- Long-term follow-up will evaluate endogenous insulin production and glycaemic control up to three years post-treatment.

## Abstract

Type 1 diabetes is characterised by progressive loss of pancreatic beta cells. Studies have shown that interleukin (IL)−17 is likely a mediator for this destruction. Whether inhibition of IL-17 could preserve beta cell function in people with new-onset type 1 diabetes is unknown.

In this phase 2, randomised, multicentre, placebo-controlled, double-blind trial conducted at 17 study sites in Sweden, 127 adults aged 18–45 years old with newly diagnosed type 1 diabetes will be enrolled. Participants will be randomised to receive either subcutaneous IL-17 inhibitor or placebo for 52 weeks, in addition to their conventional therapy. The primary endpoint will be change in residual insulin secretion measured by the area under the curve for C-peptide in response to 2-hour mixed meal tolerance test between baseline and week 52. Additionally, masked continuous glucose monitoring will be performed during 14 days at the run-in period, week 13, week 26 and week 52. Secondary endpoints will be change in time in glucose range (3.9–10 mmol/L), time in hypoglycaemia (<3.9 mmol/L), HbA1c and mean insulin dosage per kilogram body weight. Patient-reported outcomes will be evaluated with questionnaires at baseline, week 26 and 52. Additionally, 1 and 3 years after the end of the treatment period, the participants will be examined during a visit regarding endogenous insulin production, glycaemic control, glucose metrics and insulin doses.

Approvals were obtained from the Swedish Ethical Review Authority (Dnr 2020–05098) and the Swedish Medical Products Agency (Dnr 5.1-2021-105808) before participant enrolment. Participants provide informed consent before inclusion. Results of this study will be submitted for publication in international peer-reviewed journals and key findings will be presented at international scientific conferences.

ClinicalTrials.gov, NCT04589325.