Longeveron Reports Mixed Results from Hypoplastic Left Heart Syndrome Clinical Trial
News related to:Longeveron Inc · 3 min read
Longeveron Inc., a clinical-stage biotechnology company, has announced the top-line results of its Phase 2b clinical trial, ELPIS II, evaluating the investigational stem cell therapy laromestrocel as an adjunct to Stage 2 palliative surgery in infants with hypoplastic left heart syndrome (HLHS). The trial did not meet its primary endpoint of improvement in right ventricular ejection fraction (RVEF) at month 12. However, the company is continuing to analyze exploratory clinical endpoints and plans to discuss the results with the U.S. Food and Drug Administration (FDA) to determine a potential path forward.
The ELPIS II trial involved 40 infants with HLHS, randomized 1:1 to receive a single intramyocardial dose of laromestrocel during Stage 2 palliative surgery or standard-of-care surgery alone. The primary endpoint was the difference between groups' change from baseline in RVEF at 12 months, assessed by cardiac magnetic resonance (CMR). In the intent-to-treat (ITT) population, the least-squares mean difference between treatment groups was -0.7 percentage points (95% CI: -7.3 to 5.9; p=0.8336).
Despite the primary endpoint not being met, the trial did show some positive outcomes. Over a 12-month period, there were no deaths in patients that received laromestrocel, compared to one patient in the control group. Long-term follow-up of transplant-free survival (up to five years across all patients) showed that the laromestrocel arm had one event (out of 17 patients) versus two events (out of 21 patients) in the standard-of-care arm. Hospitalization burden was similar between the two arms.
Additionally, the trial demonstrated a safety profile consistent with prior clinical trials. Treatment-emergent adverse events (TEAEs) and treatment-emergent serious adverse events (TE-SAEs) were reported in 94.1% and 64.7% of laromestrocel-treated participants, respectively, compared with 100% and 71.4% of control participants. No new safety signals were identified, and no TEAEs or TE-SAEs were assessed by investigators as related to laromestrocel.
Sunjay Kaushal, M.D., Ph.D., a professor of surgery at the University of Nevada, Las Vegas, commented, "There remains a significant unmet medical need to boost the survival of the babies undergoing standard-of-care surgeries, which still have only a 50-60% survival rate to adolescence with approximately 20% requiring heart transplants. ELPIS II provides evidence of the safety of using stem cells to address this unmet need."
Longeveron plans to conduct additional analyses of the complete dataset and intends to discuss the results with the FDA to determine potential next steps for the HLHS development program. The company has initiated a process to review all options with the goal of maximizing shareholder value, including engaging an investment bank to act as a strategic advisor.
The company is also exploring funding sources and potential revenue opportunities to advance laromestrocel in longevity and aging-related frailty. Results from a Phase 2b clinical trial demonstrated that intravenous laromestrocel improved the physical condition of patients with age-related clinical frailty after nine months, compared to placebo. These results were published in Cell Stem Cell in February 2026. Longeveron was selected as a Milestone 2 Awardee team in the XPRIZE Healthspan competition and received a $1,000,000 Milestone 2 Award to be used towards future competition clinical trials.
Longeveron's lead investigational product, laromestrocel (Lomecel-B®), is an allogeneic mesenchymal stem cell (MSC) therapy product isolated from the bone marrow of young, healthy adult donors. The company is pursuing four pipeline indications: hypoplastic left heart syndrome (HLHS), Alzheimer’s disease, pediatric dilated cardiomyopathy (DCM), and aging-related frailty. Laromestrocel development programs have received five distinct and important FDA designations: for the HLHS program - Orphan Drug designation, Fast Track designation, and Rare Pediatric Disease designation; and, for the AD program - Regenerative Medicine Advanced Therapy (RMAT) designation and Fast Track designation.