Twenty years after the identification of the mutant gene that causes Huntington’s disease, scientists are ready to take therapies that target it into human trials. Studies in mouse models suggest that transiently squelching production of the gene product, huntingtin, with antisense oligonucleotides improves motor skills and behavior for months, raising hopes that this approach might work in people (see ARF related news story). Recently, Isis Pharmaceuticals, Carlsbad, California, announced that it will partner with Roche, headquartered in Basel, Switzerland, to further develop HD antisense technology (see press release). At least three other companies expect similar strategies for lowering mutant huntingtin to enter clinical trials in the next two or three years.

The nonprofit foundation Cure Huntington’s Disease Initiative (CHDI) provided research support to all four companies. Cristina Sampaio, chief clinical officer at the foundation, told Alzforum that because mutant huntingtin causes the disease, suppressing the protein represents one of the most promising treatment strategies. “The rationale could not be more compelling. This is where we have most of our hopes,” she said. Other potential HD therapies, such as the antihistamine Dimebon®, have failed in trials (see ARF related news story).

Roche will pay Isis up to $392 million to license the HD antisense technology, and will also pay royalties on any drugs that come out of the program. Roche will work with Isis to improve delivery of the oligonucleotides into the brain. Because these are large molecules, they struggle to cross the blood-brain barrier. To enhance penetrance, Roche will make use of its “brain shuttle” program (see ARF related news story). Roche declined to provide details about the shuttle program to Alzforum.

Other companies are pursuing a range of methods to silence the gene. Sangamo Biosciences in Richmond, California, in collaboration with Shire AG, based in Dublin, Ireland, is developing a zinc finger DNA-binding protein to turn down expression of the mutant huntingtin gene while leaving the healthy gene untouched (see press release). Medtronic Inc., headquartered in Minneapolis, Minnesota, and Alnylam Pharmaceuticals, Cambridge, Massachusetts, will use a pump to deliver interfering RNA (RNAi) to the central nervous system (see press release). By contrast, Genzyme, also in Cambridge, is using a viral vector to deliver RNAi to neurons, Sampaio said, but that company, too, declined to provide information.

These programs still face many challenges, Sampaio said, including delivering the therapeutics to the right place and in the right quantities to halt the disease. Sampaio also noted the need for better biomarkers to measure drug effectiveness. Several ongoing studies, such as TRACK-HD, Track-On HD, and PREDICT-HD, are gathering data on imaging and behavioral changes that mark disease progression (see ARF related news story). Sampaio expects upcoming clinical trials to help answer many of these questions. “I’m very cautious about the first trials. I think we have a huge opportunity to learn in the next two years, but we will not have an immediate treatment, because we have to fine-tune issues about how to deliver, how to dose, and how to truly manage this technology,” Sampaio said.––Madolyn Bowman Rogers.

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References

News Citations

  1. “Huntingtin Holiday” Helps Mice Back to Health
  2. Paper Alert—HORIZON Trial Data Published
  3. Q&A With Roche’s CNS Leader Luca Santarelli
  4. Study Finds Ways to Predict, Track Huntington’s Disease

External Citations

  1. press release
  2. Cure Huntington’s Disease Initiative
  3. press release
  4. press release
  5. TRACK-HD
  6. Track-On HD
  7. PREDICT-HD

Further Reading

News

  1. Huntington’s Strategies Tap Transcription, Htt Phosphorylation
  2. “Huntingtin Holiday” Helps Mice Back to Health
  3. Paper Alert—HORIZON Trial Data Published
  4. Q&A With Roche’s CNS Leader Luca Santarelli
  5. Study Finds Ways to Predict, Track Huntington’s Disease
  6. Huntington Disease: Three Ways to Tackle Triplet Disorder
  7. Keystone: More Than Mere Nucleotides—miRNAs as Master Regulators, Part 2
  8. Research Brief: Targeting Trinucleotide Repeats Tamps Toxic RNAs
  9. Dimebon for HD—A Hint of Cognitive Benefit?
  10. No Effect Seen in Huntington’s Disease Trial of Dimebon
  11. Tracking Huntington’s: Could Histone Protein Hit The Mark?
  12. Sirtuin Bests Huntingtin in Tug-of-War for Neural Survival
  13. Stem Cell News: Can RNAi Get to the Htt of the Matter?