Longeveron HLHS stem cell trial misses primary endpoint
Longeveron has reported that its Phase 2b ELPIS II trial of laromestrocel in hypoplastic left heart syndrome (HLHS) failed to meet its primary efficacy endpoint. The study, conducted in 40 infants undergoing Stage 2 palliative surgery, measured change from baseline in right ventricular ejection fraction (RVEF) at 12 months. The least-squares mean difference between treatment groups was −0.7 percentage points (95% CI: −7.3 to 5.9; p=0.8336), indicating no statistically significant improvement over standard of care.
The Miami-based company said it will conduct additional analyses of the complete dataset and intends to request a meeting with the US Food and Drug Administration to discuss potential next steps. Longeveron noted that the FDA had previously signalled its willingness to meet following completion of the study, and had already indicated that RVEF alone would not be sufficient to demonstrate efficacy for regulatory approval.
Exploratory signals and safety data
Despite missing the primary endpoint, Longeveron pointed to several exploratory findings it intends to discuss with regulators. Over a 12-month period, no deaths occurred among infants who received laromestrocel in the as-treated population, compared with one death in the control group. In longer-term follow-up of up to five years, the laromestrocel arm recorded one transplant-free survival event among 17 patients versus two events among 21 patients in the standard-of-care arm. The company also reported approximately 31% fewer adjudicated major adverse cardiovascular events in the treated arm (12 versus 19 events), though this finding was not statistically significant in the negative binomial analysis.
The safety profile was consistent with prior studies. Treatment-emergent adverse events were reported in 94.1% of laromestrocel-treated participants and 100% of controls; serious adverse events in 64.7% and 71.4% respectively. No new safety signals were identified, and no adverse events were assessed by investigators as related to the therapy. Sunjay Kaushal, professor of cardiovascular and thoracic surgery at the University of Nevada, Las Vegas, said the trial "provides evidence of the safety of using stem cells to address this unmet need," citing the 50–60% survival rate to adolescence under current surgical approaches and a roughly 20% rate of heart transplant requirement.
Strategic review and pivot to ageing
Longeveron simultaneously announced that it has initiated a formal review of all strategic options with the aim of maximising shareholder value, and will engage an investment bank as adviser. The company said it would implement cash conservation measures while pursuing the process. Chief executive Stephen Willard described the ELPIS II readout as adding to the body of knowledge around laromestrocel and emphasised the company's intent to pursue funding for the therapy's longevity and ageing-related frailty indication, where Phase 2b results published in Cell Stem Cell in February 2026 showed improvement in physical condition versus placebo at nine months.
The strategic-review announcement alongside a trial failure is a familiar pattern for small-cap biotechs facing a narrowing cash runway. HLHS is a rare congenital heart defect affecting approximately 1,000 infants per year in the United States, and the broader paediatric cardiovascular field has seen limited late-stage activity, with most cell-therapy development concentrated in oncology and haematology. The FDA's Rare Pediatric Disease designation held by laromestrocel for HLHS carries potential priority review voucher value, which could be relevant in any licensing or asset-sale discussion.
Longeveron said it has been invited to six longevity-focused investor conferences in the fourth quarter of 2026, and remains a Milestone 2 Finalist in the XPRIZE Healthspan competition, having received a $1 million milestone award toward a future competition trial.