Vaccinex’s Drug Flounders Huntington’s Trial, but Shows Promise against Another Neurodegenerative Disease
By Ruchi Jhonsa, Ph.D.
Huntington disease is a progressive brain disorder characterized by selective loss of neurons in the striatum and cortex. This causes uncontrolled movements, emotional problems, and loss of cognition in patients affected by the disease. So far, there is no treatment to reverse or stop the disease progression; however, there are treatments such as antipsychotic drugs, antidepressants, and tranquilizers that could keep the symptoms at bay.
While the cause of this genetic disorder is well understood, the ultimate cause of neuronal death is still uncertain. It is believed that apart from factors like impairment in systems handling abnormal proteins, inflammation of the brain caused by immune system infiltration could be responsible for rapid neuronal degeneration. Therefore, by keeping the immune system in check, it is possible to dampen brain degeneration.
Vaccinex, a clinical-stage immunotherapy company, is working on HD treatments that control neuroinflammation in the brain. Its HD drug, pepinemab, is a humanized monoclonal antibody that binds and blocks the activity of semaphorin 4D, an extracellular signaling molecule that regulates the migration and function of immune and inflammatory cells. While the company hoped its HD treatment could be the first one to treat the disease, it failed to top the placebo in 179 patients with early-stage Huntington’s disease, missing the primary endpoint mark. Although the study was unable to beat the placebo with a wide margin, it showed a strong trend for beneficial change in cognition associated with disease progression.
The trial had two co-primary endpoints, which are a group of two cognitive assessments picked up from the Huntington’s Disease Cognitive Assessment Battery and Clinical Global Impressive of Change. Vaccinex believes that a combination of inappropriate endpoints, wrong patient population, and a smaller patient population is the reason for the failure of the trial. The company selected a patient population that was early in the disease progression and chose tasks that would measure the cognitive ability of the patient. Since early on, patients have lesser cognitive defects, the trial failed to detect a significant improvement in the cognitive abilities with the drug treatment over placebo.
Nevertheless, the trend is positive, and the company is planning a follow-up study that would involve patients who are beginning to show cognitive decline. To that end, the company is pushing the drug in Alzheimer’s trials where the patients’ primary symptom is cognition deficit. Vaccinex has received $3 million from the Alzheimer’s Drug Discovery Foundation to test the drug in Alzheimer’s patients.
Dr. Zauderer further noted that “The insights gained from this study also suggest that pepinemab might be an important treatment option for Alzheimer’s and other neurodegenerative diseases known to affect frontal cortex primarily and to impact cognition. As previously reported, imaging data indicate that these are the brain regions most affected by pepinemab treatment. The company has, accordingly, initiated screening and expects to begin enrolling patients this month in a new Alzheimer’s disease study of pepinemab at 15 clinical sites in the United States. In line with the company’s ongoing efforts in Alzheimer’s, as well as in head and neck cancer, the company also intends to examine and, as appropriate, prioritize and balance its budget and expenditures.”
Vaccinex also believes that a higher dose of the drug could be beneficial and will test it in the future. Additional results from the trials, including a broader examination of motor activity and outcomes for a smaller group of 86 pre-manifest subjects, will be reported in detail at the upcoming 2020 Huntington’s Study Group Conference on October 30.
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