Larimar Therapeutics Stock Slumps Pre-market Over High Anaphylaxis Rate In Drug Study

The company said that anaphylaxis or a severe allergic reaction was reported in seven participants in the open-label study evaluating Nomlabofusp in participants with Friedreich’s ataxia.
Stock market down on a black background. | Image source: Yuichiro Chino via Getty Images
Stock market down on a black background. | Image source: Yuichiro Chino via Getty Images
Profile Image
Anan Ashraf·Stocktwits
Updated Sep 29, 2025   |   11:09 AM GMT-04
Share
·
Add us onAdd us on Google

Larimar Therapeutics, Inc. (LRMR) on Monday announced positive data from an ongoing long-term open-label study evaluating daily subcutaneous injections of Nomlabofusp in participants with Friedreich’s Ataxia.

Friedreich's Ataxia (FA) is a rare, inherited disorder causing progressive damage to the nervous system, leading to symptoms like poor coordination, difficulty walking, and sensory loss, as well as heart disease and scoliosis. It is caused by a mutation in the FXN gene, resulting in a deficiency of the mitochondrial protein frataxin.

In the study, an increase in skin frataxin (FXN) levels was observed with short- and long-term daily Nomlabofusp. All ten participants with data at six months achieved skin FXN levels over 50% of median levels in healthy volunteers, the company stated. It added that consistent directional improvement across multiple clinical outcomes was also observed after a year of Nomlabofusp treatment.

“These new data, as well as the improvement in abnormal lipid profiles observed in prior completed studies, provide support that nomlabofusp increases FXN in patients with FA and that the strategy of FXN replacement has the potential to result in a clinical benefit,” said CEO Carole Ben-Maimon.

Shares of the company tumbled 47% in the pre-market session after the company reported that anaphylaxis, or a severe allergic reaction, was observed in seven participants in the open-label study, and they were subsequently withdrawn from the study. Most instances of anaphylaxis occurred on the initial day of administration and most within the first six weeks of dosing, it noted.

Other discontinuations in the study included three cases of generalized urticaria, one seizure, one vasovagal event, and two non-treatment-related discontinuations, it said.

The company said that it consulted experts and decided to modify its starting dose regimen after the two most recent cases of anaphylaxis. The U.S. Food and Drug Administration has agreed with the approach, the company said. Larimar is looking to submit an application for approval of Nomlabofusp to the FDA in the second quarter of 2026.

On Stocktwits, retail sentiment around LRMR stock stayed within the ‘extremely bullish’ territory over the past 24 hours, while message volume stayed at ‘extremely high’ levels.

LRMR stock is down by 2% this year and by 42% over the past 12 months. 

Read also: Pharma Lobby Announces New Website To Connect Patients With Manufacturer-Direct Purchase Programs

For updates and corrections, email newsroom[at]stocktwits[dot]com.

Share
·
Add us onAdd us on Google
Read about our editorial guidelines and ethics policy