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SIGNAL: A new investigational approach to early treatment of Huntington’s disease

NOTE: This study has concluded and is no longer enrolling.

Vaccinex and the Huntington Study Group (HSG) launched a trial for people with the gene mutation that causes HD who are either early in the progression of the disease or are not yet diagnosed with the disease.

The SIGNAL trial is designed to assess the safety, tolerability, and effectiveness of VX15, a novel monoclonal antibody, in people with late prodromal (not yet diagnosed) or early manifest (early in the progression of the disease) HD. It is a Phase 2, multi-center, randomized, double-blind, placebo-controlled study being conducted at approximately 30 sites across the United States and Canada. The trial seeks to enroll a total of 240 individuals, 21 or older.

The trial has two cohorts. Cohort A, which consisted of the trial’s first 36 participants, is now complete. Those participants were treated for six months with either drug or placebo (1:1); then all participants were treated with study drug for six months, followed by three months of follow up.

Enrollment in Cohort A is complete. To view the press release from Vaccinex, click here. To view a press release from Vaccinex about preliminary imaging data from Cohort A, click here. To view the HDSA webinar by Vaccinex President & CEO Maurice Zauderer, click here.

Enrollment in Cohort B is complete. To view the press release from Vaccinex, click here.

The investigational compound being studied in the trial is VX15, a monoclonal antibody. This is a different class of drug than any other drug used in previous HD clinical trials. Monoclonal antibodies are more specific than most other drugs because they bind to and neutralize their desired target with high specificity. Previous nonclinical research and the results of Cohort A (see HDSA webinar regarding interim results by clicking here) suggest that VX15 may have the potential to slow the progression of brain inflammation, which has been shown to impair thinking, movement, and behavior in HD animal models.

VX15 has not been approved by the FDA; its potential benefits for HD are being investigated within the SIGNAL trial.

The VX15 antibody is designed to bind specifically to the semaphorin 4D (SEMA4D) protein, a molecule that guides the activation and movement of cells within the body. In HD, VX15 has the potential to block SEMA4D, which may be responsible for inflammation in the brains of individuals who develop HD. Reducing brain inflammation may slow HD’s subsequent effects, including impaired cognition, movement, and behavior.

The Cohort B study procedures involve:

  • A screening visit to confirm eligibility. Approved subjects will complete a baseline visit and then begin the investigational period
  • Once a month study drug or placebo delivery through an intravenous infusion that takes at least one hour
  • Brain imaging and cognitive testing during specified visits – these monthly visits may take a full day to complete
  • Lumbar puncture for collection of cerebrospinal fluid on one occasion for subjects in Cohort B who volunteer
  • Safety, tolerability, and efficacy assessments will be performed at all visits
  • Participants will be treated with study drug or placebo intravenous infusion for 18 months and will take part in safety follow-up visits for up to six months after the final treatment

SIGNAL participants may enroll in observational studies, but they cannot participate in other clinical trials of investigational compounds while they are participating in SIGNAL. However, SIGNAL study participants may be eligible for other clinical studies once they complete the SIGNAL trial.

Participants may still be eligible for SIGNAL if they are taking other prescribed medications that are FDA approved.

If you would like additional information or have questions regarding the study, please contact the Huntington Study Group at 1-800-487-7671 or info@hsglimited.org.

UPDATE – Vaccinex Policy on Expanded Access and Compassionate Use