The biotechnology company SOM Biotech, headquartered at the Barcelona Science Park and dedicated to the discovery and development of innovative therapies for rare central nervous system disorders, has received the endorsement of the U.S. Food and Drug Administration (FDA) to continue the development of its drug SOM3355, intended for the treatment of Huntington’s disease, a rare and progressive neurological disorder. After reviewing the results of Phase 2, the FDA has given the green light to the Phase 3 study design, the step prior to potential drug approval, which will also include an open-label extension (OLE) to evaluate long-term effects.

SOM3355 is an innovative drug that acts on the brain in a multimodal way, combining the effect of a selective β-blocker with the inhibition of VMAT1 and VMAT2, two proteins that act as transporters of neurotransmitters such as dopamine within neurons. This mechanism helps regulate chemical messaging in the brain, contributing to the reduction of involuntary movements and the mood and behavioral changes typical of Huntington’s disease.

The drug has successfully completed an initial proof-of-concept study and a Phase 2b clinical trial, showing promising results that could improve patients’ quality of life and offer new hope for this hereditary neurodegenerative disease, which causes coordination and speech difficulties, anxiety, and depression.

“We are very pleased with this positive outcome with the FDA, in addition to the recent excellent feedback from the EMA; both agencies have confirmed the potential of SOM3355 for the treatment of Huntington’s disease,” said Silvia Panigone, CEO of SOM Biotech. “We appreciate the supportive and constructive discussions with the FDA and the alignment on the Phase 3 study design, which could lead to the approval of the first drug capable of addressing the complex symptomatology of Huntington’s disease, including chorea and behavioral and psychiatric symptoms such as depression and anxiety.”

Currently, authorized drugs only treat chorea, all carry a black box warning for increased risk of depression and suicidal thoughts, and have side effects difficult to distinguish from disease progression.

The results of SOM Biotech’s Phase 2b study in Huntington’s disease were very promising. Participants who received SOM3355 not only experienced a significant improvement in involuntary movements (chorea) but also showed a reduction in anxiety and improvement in depressive symptoms. Additionally, the study confirmed that the drug does not cause drowsiness, a common side effect in other treatments.

“These results, showing a positive effect on depression and anxiety, without drowsiness and with improvement in chorea, are unprecedented and address the unmet need for an effective and well-tolerated drug to treat Huntington’s disease across its different stages,” explained Rossella Medori, Chief Medical Officer (CMO) of SOM Biotech. “Efficacy on behavioral and psychiatric symptoms, along with a favorable safety profile, will make SOM3355 the symptomatic treatment of choice for Huntington’s disease,” added Panigone.

The Phase 3 clinical trial, double-blind and placebo-controlled, which will support drug approval, is scheduled to start in Q4 2026 and will test a single dose of SOM3355. Participants with mild to severe Huntington’s disease will be randomized to receive 600 mg of SOM3355 daily or a placebo for three months (12 weeks). Upon completion of the study, participants will have the option to join a nine-month open-label extension (OLE) to assess the potential positive impact on disease progression.

“We are fully committed to moving forward with the pivotal trial and continuing discussions with the FDA. The alignment with the Agency on a three-month study gives us a short timeframe for potential approval,” concluded Medori.

» Link to the news: SOM Biotech website [+]