LGVN Stock Slips After Hours As FDA Flags Concerns On Rare Heart Defect Trial Design

• The agency explicitly stated that the trial’s current primary endpoint is “not an appropriate endpoint to demonstrate efficacy.”
• As a result, the FDA no longer considers the study to be “pivotal.”
• Top-line data from the 40-patient randomized, controlled study are still expected in August 2026.

Longeveron Inc. (LGVN) shares fell 4% in after-hours trading on Friday after the U.S. Food and Drug Administration expressed reservations on the trial design for its cell therapy laromestrocel.

Longeveron announced that it held a meeting with the FDA in late March 2026 to discuss the ongoing mid-stage trial of its investigational cell therapy laromestrocel in infants with hypoplastic left heart syndrome (HLHS), a severe, rare congenital heart defect where the left side of a baby's heart is severely underdeveloped and cannot properly pump blood to the body. Though the firm called the meeting ‘constructive’, investors seem more focused on the agency’s reservations about the trial’s design and its potential to support approval.

Meeting Outcomes

The FDA acknowledged that HLHS is a rare, life-threatening congenital heart defect with “significant morbidity and mortality” and a high unmet medical need. However, the agency explicitly stated that the trial’s current primary endpoint is “not an appropriate endpoint to demonstrate efficacy.”

Longeveron said it agreed with the FDA’s assessment that the endpoint alone is insufficient. Though the company had hoped to discuss alternative or composite endpoints, the FDA indicated it could not agree to a new primary endpoint while the trial is still ongoing, it said.

As a result, the FDA no longer considers the study to be “pivotal” — a designation the agency had previously discussed with the company.

The release noted that the FDA is “willing to meet with Longeveron again when the ongoing ELPIS II study is completed to discuss the study results and align on a potential path forward.” Top-line data from the 40-patient randomized, controlled study are still expected in August 2026

The agency emphasized that only the most objective clinical measures — all-cause mortality, cardiac transplant-free survival, events of cardiac transplantation, and well-defined major adverse cardiac events (MACE) — would be considered informative for efficacy. Longeveron said it is already capturing those endpoints, along with additional supportive measures.

The company plans to submit a revised plan featuring a composite primary endpoint and secondary endpoints for FDA review. It remains “optimistic” that the full dataset, combined with other evidence, will still support an application filing after the August readout.

How Did LGVN Retail Traders React?

On Stocktwits, retail sentiment around LGVN stock improved from ‘bearish’ to ‘neutral’ territory over the past 24 hours, while message volume increased from ‘low’ to ‘normal’ levels.

A Stocktwits user said that they will take their loss with the company.

Another highlighted the negative takeaways from the meeting.

LGVN stock has fallen 43% over the past 12 months. 

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