Why Did Larimar Therapeutics’ Stock Surge Over 30% Pre-Market Today?

The FDA has granted Breakthrough Therapy Designation to Larimar’s frataxin protein replacement therapy, nomlabofusp.

• The therapy is to treat adults and children with Friedreich’s ataxia, a progressive neurodegenerative disorder.
• Preliminary findings from the open-label study show that nomlabofusp increased FXN levels in patients’ skin to amounts observed in asymptomatic carriers. 
• FDA agreed that skin FXN could serve as a novel surrogate endpoint, supporting the planned Biologics License Application submission.

Larimar Therapeutics, Inc. (LRMR) announced on Tuesday that the U.S. Food and Drug Administration (FDA) has granted Breakthrough Therapy Designation (BTD) to its frataxin (FXN) protein replacement therapy, nomlabofusp. 

The therapy is to treat adults and children with Friedreich’s ataxia (FA), a progressive neurodegenerative disorder causing nervous system damage.

FDA Endorses Skin FXN As Surrogate Endpoint

The FDA’s decision follows encouraging clinical data from Larimar’s ongoing open-label study and a recent Support for Clinical Trials Advancing Rare Disease Therapeutics (START) pilot program meeting. 

The agency also agreed that skin FXN could serve as a novel surrogate endpoint reasonably likely to predict clinical benefit, supporting the planned Biologics License Application (BLA) submission targeted for June 2026. The FDA additionally confirmed that the planned analyses, reference population, and clinical endpoints are aligned with BLA requirements.

Following the FDA’s decision, Larimar stock traded over 30% higher in Tuesday’s premarket. On Stocktwits, retail sentiment around the stock jumped to ‘extremely bullish’ from ‘bearish’ territory the previous day. Message volume shifted to ‘extremely high’ from ‘high’ levels in 24 hours. 

Encouraging Clinical Data

Preliminary findings from the open-label study show that nomlabofusp increased FXN levels in patients’ skin to amounts observed in asymptomatic carriers. 

Improvements were seen across four key clinical measures, the modified Friedreich Ataxia Rating Scale (mFARS), FARS-Activities of Daily Living (ADL), 9-Hole Peg Test (9-HPT), and Modified Fatigue Impact Scale (MFIS) after one year of treatment. 

The results suggest that nomlabofusp could slow or reverse FA progression compared with the natural disease course observed in the Friedrich’s Ataxia Clinical Outcomes Measure Study (FACOMS).

LRMR stock declined by over 7% in the last 12 months. 

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