AMO DM1 Therapy Misses Primary Endpoint in Pivotal Study

Rare Daily Staff

AMO Pharma its experimental therapy AMO-02 to treat myotonic dystrophy in children and adolescents failed to reach its primary endpoint of a statistically significant benefit over placebo based on the FDA-authorized physician-completed rating scale the pivotal REACH-CDM clinical study.

The company said the topline results from the study showed a positive benefit in both the treatment and placebo groups, which may be attributed to difficulties in patient monitoring and compliance with reporting protocols caused by the COVID pandemic.

AMO said the study did show a statistically significant benefit over placebo based on the FDA-authorized physician-completed rating scale. Clinically and statistically significant benefit was achieved during analysis of a range of functional and objective assessments in the treatment group compared to placebo.

Results will be reviewed on Saturday, September 9 at 3:30 PM ET in a briefing event during the 2023 Annual Meeting of the Myotonic Dystrophy Foundation being held at the Renaissance Washington D.C. Downtown Hotel.

Myotonic dystrophy type I, also known as DM1, is the most common form of the disease. Adults with DM1 may eventually become physically disabled and loss of muscle control can make it difficult to perform simple physical tasks such as holding a cup, writing or opening a door. Loss of control in muscles in the mouth and throat can affect the ability to talk, eat, and drink. If swallowing difficulties become extreme, patients may need to be fed through a feeding tube. The range and severity of symptoms of DM1 can make it difficult or impossible for many patients to work, care for themselves or their families, or live independently. Symptoms can progress to the point where they become life threatening. Babies born with the congenital form of DM1 are more severely affected and may experience life-threatening symptoms.

AMO-02 is in development for the treatment of congenital myotonic dystrophy and has potential for use in adult-onset myotonic dystrophy, and additional central nervous system, neuromuscular, and other orphan indications. AM0-02 is a clinical stage investigational medicine for the treatment of the severe form of congenital myotonic dystrophy known as CDM1 or Steinert disease. AMO-02 has a dual mechanism disrupting the pathogenic RNA repeat in CDM1 and inhibiting excess levels of the kinase GSK3β.

Treatment with AMO-02 was associated with clinically significant improvements in cognitive performance, reduction in a widely used biomarker of skeletal and cardiac muscle integrity, and improvement in the 10m walk/run test. A composite statistical analysis of outcomes assessing motor skills, muscle strength, cognitive ability, daily living skills, and biomarker data showed a statistically significant benefit of treatment with AMO-02 compared to placebo.

The benefits seen with AMO-02 were related to pharmacokinetic parameters showing that increased plasma levels of AMO-02 resulted in greater clinical improvement.

Patients enrolled in the REACH-CDM trial were invited to continue treatment in an open-label extension study (OES) and 98 percent of patients opted to continue treatment in that study. Patients were again given the option of continuing treatment at the conclusion of the 1-year OES study and 85 percent of patients opted to continue treatment.

“These results provide strong further validation of the potential benefits of treatment with AMO-02 in multiple key areas that represent the most severe symptoms and disabilities associated with DM1,” said Ibs Mahmood, CEO at AMO Pharma. “We are now working to discuss next steps with regulators in order to advance this program.”

Photo: Ibs Mahmood, CEO at AMO Pharma