SOM3355 reduces chorea in Huntington's disease

Treatment with bevantolol hydrochloride (SOM3355) is well tolerated and results in a reduction in chorea among patients with Huntington’s disease (HD), a study has shown.

A research team conducted this randomized, placebo-controlled, proof-of-concept study in 32 HD patients assigned to two arms of four sequential 6-week periods each. Patients received placebo and SOM3355 at 100 and 200 mg twice daily in a crossover design.

The researchers then assessed whether participants improved by at least two points in the total maximal chorea score (primary endpoint) in any active drug period relative to the placebo period.

More than half of the patients (57.1 percent) met the primary endpoint. Of these, 28.6 percent achieved an improvement of ≥3 points, 25.0 percent ≥4 points, 17.9 percent ≥5 points, and 10.7 percent ≥6 points compared with placebo.

On mixed-model analysis, SOM3355 200 mg twice daily demonstrated a significant improvement in the total maximal chorea score of ‒1.14 (95 percent confidence interval, ‒2.11 to ‒0.16; p=0.0224) relative to placebo treatment. These results were consistent with the Clinical and Patient Global Impression of Change ratings (secondary endpoints).

The research team recorded a 1.7‒1.9-fold increase in the levels of plasma prolactin (p<0.005), which potentially indicated the effect on the dopamine pathway, consistent with vesicular monoamine transporter type 2 inhibition. In addition, they observed mostly mild to moderate adverse events during SOM3355 administration.

“Larger studies are necessary to confirm its therapeutic utility as an antichoreic drug,” the researchers said.