Glioblastoma has a grim arithmetic. Most people diagnosed with it die within 15 months, the five-year survival rate sits below 5 percent, and no immunotherapy has ever been shown to extend life in this cancer. On July 12, 2026, a Seattle company announced it would try again, in Montreal.
HDT Bio Corp. has set up a Canadian subsidiary, HDT Bio Canada Inc., and joined forces with McGill and with The Neuro, formally the Montreal Neurological Institute-Hospital, to take an experimental treatment called HDT-401 into a Phase 1 trial. The study will run with Roberto Diaz of The Neuro, and colleagues across McGill-affiliated institutions. The Canadian regulatory paperwork is not finished: the company has sat down with Health Canada for a pre-submission meeting on the trial application and says the feedback was constructive, which moves it toward a formal submission.
What is in the vial
Under the hood, HDT-401 is two things bolted together. One is Riboxxim, an engineered molecule that stimulates two innate immune sensors, TLR3 and RIG-I, licensed from the Dresden firm Riboxx GmbH. The other is HDT Bio’s own LION lipid delivery system, which the company says has been used in more than 6,000 patients across various programmes.
The idea is to put the drug where the tumour is, either into the growth itself or into the cavity left after surgery. There it is meant to switch the local environment from immune-suppressed to immune-engaged, prompting inflammatory signalling and drawing immune cells in. Keeping the dose local also limits how much reaches the rest of the body. Glioblastoma is notorious for shutting down immune activity around itself, so that is the lock being picked.
The treatment has already been given to some glioblastoma patients under compassionate use. Chief executive Steven Reed said what the company saw was encouraging, and that is why it is “moving as fast as we can to get this into a formal trial in Canada.” Those early results helped shape the design of the trial.
The surgeon’s view
Diaz put it in surgical terms. “When you operate on these patients, you understand the problem in a way that is difficult to convey,” he said. “You resect what you can. You know what remains. And you know the current tools are not enough.” The recurrence problem, he added, comes from a tumour that suppresses immune activity locally, and an approach aimed at that suppression at the tumour bed is where he thinks the science points.
Jacques Rohayem, who invented Riboxxim and runs Riboxx, said the molecule was engineered to give precise, repeatable immune activation, avoiding the unpredictability that held back earlier TLR3 agonists.
The company is also pursuing a breast cancer vaccine in Canada and has lined up Northern RNA of Calgary to make it under GMP standards. HDT-401 itself has no approval from Health Canada, the US Food and Drug Administration or any other regulator.
Sources
- A New Approach to Treating Brain Cancer: HDT Bio Launches Canadian Clinical Program at McGill University (PR Newswire)
- HDT Bio Launches Canadian Phase 1 Trial of HDT-401, a Locally Administered RNA Immune Activator for Glioblastoma (MedPath)
