Zenas BioPharma (ZBIO) Study Result summary

INDIGO Phase III Trial Design and Objectives

• The INDIGO Phase III trial was a multicenter, randomized, double-blind, placebo-controlled study evaluating obexelimab in IgG4-RD, enrolling 194 patients globally with balanced baseline characteristics.

• The primary endpoint was time to first disease flare through week 52; key secondary endpoints included flare rate, remission, and rescue medication use.

• Weekly subcutaneous dosing was used, and all participants could enter an open-label extension.

Efficacy Results

• Obexelimab reduced the risk of IgG4-RD flare by 56% versus placebo (HR=0.443, p=0.0005), with 27% of obexelimab patients experiencing flares versus 55% on placebo.

• All four key secondary endpoints were met, including time to flare, flare rate, complete remission, and reduced glucocorticoid rescue therapy use.

• Over 70% of patients on obexelimab were protected from flares at 52 weeks.

Safety, Tolerability, and Subgroup Insights

• Obexelimab showed a favorable safety profile, with lower rates of serious adverse events (10% vs. 19%) and infections compared to placebo; injection site reactions were similar between groups.

• No new safety signals or increased risk of malignancy were observed.

• No correlation was found between B-cell count and infection rates.

• Flare events in the obexelimab arm leveled off after steroid taper, with separation from placebo seen post-taper.