Zenas BioPharma Completes Targeted Enrollment of the Phase 3 INDIGO Trial of Obexelimab in Immunoglobulin G4-Related Disease

Zenas BioPharma, Inc. recently announced the completion of its targeted enrollment for the Phase 3 INDIGO trial of its lead product candidate, obexelimab, for the treatment of patients with IgG4-RD.

“With the completion of targeted enrollment in our INDIGO trial, the largest IgG4-RD clinical trial ever conducted, Zenas has demonstrated its capabilities to execute on our expansive clinical development plans for obexelimab,” said Lonnie Moulder, Founder and Chief Executive Officer of Zenas. “Importantly, we expect to report topline results by the end of next year and advance the Company toward our goal of becoming a leader in the development and commercialization of transformative immunology-based therapies for patients in need.”

 The Phase 3 INDIGO trial is a global, registration-directed, double-blind, placebo-controlled trial designed to evaluate the safety and efficacy of obexelimab in approximately 190 patients with active IgG4-RD and is being conducted at approximately 100 sites in 20 countries. Following an initial screening period, patients were randomized 1:1 to 250 mg of obexelimab or placebo administered as a subcutaneous injection every seven days for 52 weeks, followed by an opportunity for eligible patients to continue in an open-label extension period where all patients will receive treatment with obexelimab.

The primary efficacy endpoint of INDIGO is the time to first IgG4-RD flare, as determined per protocol by the investigator and the adjudication committee. Secondary endpoints include annualized flare rate, the proportion of patients achieving complete remission, and use and quantity of rescue medication. More information on the INDIGO trial (NCT05662241) is available at clinicaltrials.gov.

Obexelimab is a bifunctional monoclonal antibody designed to bind both CD19 and FcγRIIb, which are broadly present across B cell lineage, to inhibit the activity of cells that are implicated in many autoimmune diseases without depleting them. This unique mechanism of action and self-administered, subcutaneous injection regimen may broadly and effectively address the pathogenic role of B cell lineage in chronic autoimmune disease.

Obexelimab has been evaluated in five completed clinical trials in a total of 198 patients who received obexelimab either as an intravenous infusion or as a subcutaneous injection. Obexelimab was well tolerated and demonstrated clinical activity across these five clinical trials, providing the Company an initial clinical proof of concept for obexelimab as a B cell inhibitor for the treatment of patients living with certain autoimmune diseases. Currently, Zenas is conducting multiple Phase 2 and Phase 3 trials of obexelimab in several autoimmune diseases including IgG4-RD, Multiple Sclerosis, Systemic Lupus Erythematosus, and warm Autoimmune Hemolytic Anemia.

IgG4-RD is a chronic fibro-inflammatory disease that can affect virtually all organ systems, including the pancreas, biliary tract, salivary and lacrimal glands, lungs, and kidneys. Patients with IgG4-RD may present with a single organ involved but more frequently present with multiple organ involvement. As the disease progresses and patients experience new or worsening symptoms (ie, flares), lesions develop in additional organs and the cellular inflammation characterizing early disease moves toward a more fibrotic stage, which can lead to major irreversible tissue damage and ultimately organ failure. We estimate that the currently diagnosed population of IgG4-RD patients in the US is approximately 20,000, with comparable prevalence rates globally.

Despite the growing recognition of IgG4-RD and advances in the understanding of its pathophysiology, there are no approved therapies for the treatment of this disease and there remains high unmet medical need. The current standard of care is treatment with glucocorticoids (GCs). Although GCs are initially effective, treatment with GCs can often result in various complications and co-morbidities. Most patients can relapse within 12 months of discontinuing GC treatment, and maintenance therapy with GCs has not been shown to prevent recurrence of disease.

The pathogenesis of IgG4-RD suggests that B cell-targeted therapies may provide therapeutic benefit. Although not approved by any regulatory authorities to treat IgG4-RD, certain B cell depleting agents (eg, rituximab) are occasionally administered to patients with IgG4-RD. However, B cell depleting agents are often associated with infections, including serious opportunistic infections, and can compromise a patient’s ability to mount a response to vaccinations.

Zenas is a clinical-stage global biopharmaceutical company committed to becoming a leader in the development and commercialization of transformative immunology-based therapies for patients in need. Our core business strategy combines our experienced leadership team with a disciplined product candidate acquisition approach to identify, acquire and develop product candidates globally that we believe can provide superior clinical benefits to patients living with autoimmune diseases. Zenas’ lead product candidate, obexelimab, is a bifunctional monoclonal antibody designed to bind both CD19 and FcγRIIb, which are broadly present across B cell lineage, to inhibit the activity of cells that are implicated in many autoimmune diseases without depleting them. We believe that obexelimab’s unique mechanism of action and self-administered, subcutaneous injection regimen may broadly and effectively address the pathogenic role of B cell lineage in chronic autoimmune disease. For more information, visit www.zenasbio.com.