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Update on GENERATION HD1 and GEN-EXTEND

Today, April 27, was the first day of the annual CHDI Conference. Roche had the opportunity to present about the data and results from their recently halted clinical trials, Roche’s GENERATION HD-1 and GEN-EXTEND studies. Unfortunately, the data released today give rise to some significant concerns. This news will be hard for our patients and patient families. If you need support, a series of resources is listed below.

In our note on March 23 (https://www.huntingtonsociety.ca/roche-generation-hd1-clinical-trial-prematurely-stopped/), we discussed Roche’s decision to stop dosing in GENERATION HD1, based on a recommendation from the independent data monitoring committee (iDMC). Their decision was made after considering study drug tominersen’s potential benefit–risk profile for study participants. At that time, we were not told of the reason for stopping; we were just made aware of the reason for that today.

Here is what we learned today after Roche’s preliminary review of the data:

  • Treatment Groups: Patients receiving the drug did not have a reduced rate of progression of their HD symptoms compared to those on placebo. The study did not achieve its goal of slowing HD progression.
  • Patients receiving tominersen deteriorated faster than those on placebo, identifying that the drug treatment had worse outcomes based on the results of many motor and cognitive tests.
  • Patients receiving tominersen every 8 weeks (120 mg Q8W): On average, this group’s progression was worse than those receiving less frequent dosing or placebo.
  • Patients receiving tominersen every 16 weeks (120 mg Q16W): This group had results that were slightly worse than placebo but they were not statistically significant.
  • Safety Issues and Side Effects: The study also showed that there was a dose-related enlargement of the fluid-filled structures called ventricles in the brain.
  • Take-home message: Tominersen did not help slow or stop HD symptoms from getting worse. Patients getting treatment did worse than placebo treatment and this was an unexpected result and was the reason why the study dosing was stopped.
  • It is unclear if the deterioration is temporary or permanent and further study is needed.

Background

  • Roche’s clinical trial program involved a series of studies which included the original phase 1 study, the Natural History Study and the GENERATION HD1 study. All three studies were conducted in Canada and patients who participated in the studies were able to participate in open label studies and received tominersen over time, in some cases a duration of years. The first patient treated in these studies was in Canada.
  • These clinical trials were designed to evaluate if treatment with tominersen would slow disease progression. This is very different than what would be expected if a drug is meant to improve symptoms. A placebo controlled study is required to show a difference in disease progression. Studies involve assessments that include the primary outcome measure to identify if the drug achieves its goals. Dosing in the studies varied but after the phase 1 study identified that 120 mg was the best dose, patients were dosed initially every month or every second month and then a modification was made to change to every 8 weeks or every 16 weeks.
  • Independent data monitoring committees (iDMCs) are important to have for the ongoing evaluation of the study to make sure that the study is not causing harm to participants and to identify any safety issues.

Future Work

GENERATION HD-1 and GEN-EXTEND will follow patients for clinical and safety outcomes and continually add to the understanding of huntingtin (HTT) lowering as a potential treatment for HD.

Roche’s next steps for the tominersen program will be guided by data and shared with the HD community, with a focus on the following:

  • While the early stop of dosing in GENERATION HD-1 is a setback, it is still a learning opportunity
  • Roche is committed to the timely analysis of the data and to sharing the lessons and next steps of their findings with the HD community

We can appreciate that this is a lot of scientific information to take in and process. For more of an explanation, please sign up for a free research webinar offered by HDSA on Thursday April 29 from 12-1:30 pm ET. Click here to register: https://hdsa-org.zoom.us/webinar/register/WN_2NZojYk6Q-q0HbwdREIffg?fbclid=IwAR0bKG6B7txi4ds1y1NT9r746873jzGAS6emi_QTagq9reH7nECLD7w7sgM

While today’s news is not good and demonstrates the real risk patients face, even bad news is a step forward in learning more about the disease. Our research pipeline contains a variety of potential treatments and is full of hope. Please remember that HSC Family Services (FS) are available to provide support, education on HD, resources and referrals. Individuals and families can find the contact information for the nearest FS team member here: https://www.huntingtonsociety.ca/family-services-team-list/

Whether you are a person living at risk, mutation positive, symptomatic of HD, or a carer, strong emotions can surface with an announcement such as the one concerning this study. Please know there are people and places you can turn to get more information and support.

Should you or a family member be in crisis, you can contact:

As always, it is the patients who participate and their families who are the real Huntington Heroes and we are so full of gratitude and respect for their commitment and bravery.

Sincerely,

Shelly Redman
CEO
Huntington Society of Canada


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