Phase III Equator Study Results

The study results did not demonstrate a meaningful difference in complete response (CR) or overall response rate (ORR) at Day 29 between patients treated with itolizumab and placebo; however, statistically significant and clinically meaningful benefit in longer-term outcomes were achieved, including complete response at Day 99, duration of complete response and failure-free survival. Itolizumab exhibited a favorable safety and tolerability profile and did not increase the risk of clinical sequelae, including infection or sepsis, primary drivers of the high mortality associated with aGVHD.

“While we did not observe improvements in Day 29 outcomes, itolizumab demonstrated compelling clinical results in several important longer-term outcomes, conferring potential patient benefit where there are no approved therapies,” said Bruce Steel, chief executive officer at Equillium. “Based on these data and prior FDA guidance, we have filed for Breakthrough Therapy designation and have been granted a meeting to discuss the potential for Accelerated Approval of itolizumab for first-line treatment of aGVHD, a rare disease where one-year mortality exceeds 40 percent and itolizumab has already received Orphan Drug and Fast Track designations. We expect feedback from the FDA during May and, if positive, we would plan to submit a biologics license application during the first half of 2026.”

“The longer-term outcomes are important,” said Dr. John Koreth, Professor of Medicine, Dana-Farber Cancer Institute, Harvard Medical School. “There are no approvals in first-line therapy for aGVHD, and no drug candidates have been able to demonstrate efficacy beyond four weeks. To demonstrate statistical significance in pre-specified endpoints of duration of complete response and failure-free survival, compared to standard of care therapy, is clinically meaningful.”

The Phase III EQUATOR study in first-line aGVHD demonstrated a favorable safety and tolerability profile, and clinically meaningful longer-term outcomes. There was no meaningful difference in CR or ORR, the primary endpoint and a key secondary endpoint of the study (respectively), at Day 29 between patients treated with itolizumab and placebo, but statistical significance was achieved in several critically important secondary endpoints demonstrating improvement in longer term outcomes:

• i.   Statistical significance in duration of CR favoring itolizumab, with a median 336 days vs. 72 days, p-value 0.017.
• ii.  Statistical significance in failure-free survival favoring itolizumab, with a median 154 vs. 70 days, p-value 0.043.
• iii. Statistical significance in complete response at Day 99 favoring itolizumab, with 35 (44.9%) vs. 22 (28.6%) patients, p-value 0.035.
• iv. Positive trend in overall survival favoring itolizumab, with mortality of 19 (24.4%) vs. 25 (32.5%) patients.
• v.  Steroid tapering and rates of primary disease relapse and chronic GVHD were similar for both treatment arms.