In an important highlight from the 2010 CHDI meetings, Dr. Joakim Tedroff from NeuroSearch presented very encouraging preliminary results from the Phase 3 ACR-16 (Huntexil) trial in Europe. This trial will almost certainly bring forward a new drug treatment for Huntington's (HD) that significantly improves, not just stabilizes motor ability. Trial results also showed a trend toward cognitive improvement, and very importantly that there were no significant drug side effects. This drug is not only effective, it has safety features to allow its use in all those with HD. And in other promising news outside of the trial, NeuroSearch has shown that metabolic improvement occurs in the the brains of Huntington's patients who have taken the drug.
As in North America, the trial had 3 different groups: those on placebo, or a lower dose of drug (45 mg/day), or a higher dose (90 mg/ day). But differing from the North American trial, a fraction of those in each group were allowed to take neuroleptic (antipsychotic) medication.
Results from the preliminary analysis
- The benefits of Huntexil were seen only in those on the larger dose of drug.
- For those on the larger dose, there was significant improvement in the TMS (total motor score) on an average of about 3 points. This translates to an average of about 1 year of the motor change that is predicted to occur for disease progression in HD.
- The improvement occurred only in the voluntary movement component of the TMS which means those aspects of HD that cause slowness of movement and rigidity, but had no effect on chorea.
- The improvement in voluntary movement persisted through the 6-month duration of the trial and seemed to increase with time.
- There was improved oculomotor (eye movement) function, as well as dystonia (involuntary rigid muscle contractions).
- There was trend in improvement in several cognitive (thinking) measures.
- There were no significant side effects.
- There was no change in total functional capacity (TFC) scores.
- The use of neuroleptic (antipsychotic) medication had no effect on Huntexil benefit.
Remaining questions: NeuroSearch will be able to assess whether the drug benefit varies with the stage of the disease when they complete the analysis. But as happens in all clinical trials there are unanswered questions that will require more human study.
- What is best effective dosage? While the lowest effective dose was established in the trial, it is unknown whether a larger dose might - or might not -- be more effective.
- What is the effect when Huntexil is combined with Xenazine® (tetrabenazine)?
Editor's comments: Although some might be disappointed that the beneficial effects seen in this trial aren't greater, these results are truly cause for celebration. This drug improves voluntary motor function and probably improves aspects of cognition as well. We've learned that the effect lasts 6 months with possible improvement for a longer period of time. And if this weren't enough, Huntexil might modify the course of the disease since the effect of Huntexil seemed to increase with time. And it is safe for use in all people with HD.
Bottom line: This drug is a real winner. And as fast as possible we need to push enrollment over the top for ACR16 in North America. Sign up today.