β-Cell Function and Diabetes Outcomes 1 Year After Stopping Oral Baricitinib Immunotherapy for Type 1 Diabetes

The Baricitinib in New-Onset Type 1 Diabetes (BANDIT) trial showed that baricitinib treatment for 48 weeks preserved β-cell function and lowered insulin requirements and glucose in recent-onset type 1 diabetes. We aimed to determine the durability of these effects following treatment cessation.

The following posttreatment outcomes of the randomized, double-blind, placebo-controlled BANDIT trial were analyzed: C-peptide and glucagon responses to a mixed meal, HbA1c, continuous glucose monitoring (CGM) measures, CD8+ T-cell phenotype and function, and adverse events.

Of 91 randomized participants, 88 (58 baricitinib and 30 placebo) completed the week 96 follow-up. Mean ± SEM C-peptide was significantly greater in baricitinib-treated participants at week 72 (0.54 ± 0.05 vs. 0.38 ± 0.06 pmol/mL; P = 0.015) but not at week 96 (0.43 ± 0.05 vs. 0.35 ± 0.06 nmol/L; P = 0.336). No significant between-group differences in insulin dose, HbA1c, or CGM measures were observed during follow-up. Post hoc comparisons showed that when the study drug was ceased at week 48, baricitinib-treated adults (n = 28) experienced full preservation of β-cell function whereas C-peptide decreased relative to baseline by 0.09 pmol/mL in baricitinib-treated children (n = 32; P = 0.022). Baricitinib did not resolve paradoxical glucagon increase after a mixed meal. Decreased frequency and cytokine signaling of effector memory CD8+ T cells observed at week 48 resolved by week 96.

The benefits of oral baricitinib in type 1 diabetes wane over 48 weeks following treatment cessation. Durable benefit is likely to require continuous treatment.