A new article published in the journal Nature is reporting promising results from a landmark Phase 1 human trial testing a novel vaccine designed to help a patient’s immune system better target brain tumors. The data suggests the experimental vaccine is safe and stimulates a significant immune response that slows tumor progression. A larger Phase 2 trial is currently being planned.
Diffuse gliomas are a particularly difficult kind of brain cancer to treat. They can spread across the brain making it difficult to easily eliminate them through traditional surgery, but these tumors do often share a common feature – over 70 percent of low-grade gliomas have a single gene mutation affecting an enzyme called isocitrate dehydrogenase 1 (IDH1).
This IDH1 mutation is unique to gliomas and leads to the creation of novel proteins called neo-epitopes. Michael Platten, from the German Cancer Research Center, has been working for years to create a vaccine that helps a patient’s immune system learn to target these IDH1 mutated cells.
“Our idea was to support patients’ immune systems and to use a vaccine as a targeted way of alerting it to the tumor-specific neo-epitope,” says Platten.
In 2015, after years of development and animal testing, the researchers finally began a human trial for their novel IDH1 vaccine. The first step was to investigate how safe the vaccine was in human subjects and explore what kind of immune response it triggered.
Around 33 patients with a newly diagnosed IDH1 glioma were recruited. The recently published results of that Phase 1 trial reveal the experimental vaccine is safe with no serious side effects noted.
Looking at immune responses the researchers found 93 percent of patients displayed an effective response to the vaccine. Immune T cells specifically targeting the IDH1 mutation were detected in those responsive patients.
Patients with large numbers of circulating T cells in their bloodstream also showed tumor pseudoprogression, a process where a tumor grows in size due to invading immune cells causing swelling. At the three-year follow-up point the cohort’s survival rate was 84 percent. No tumor growth was seen in 82 percent of patients displaying strong immunogenic responses to the vaccine after three years.
Platten is cautious about overstating the results from this phase 1 trial, saying no further efficacy conclusions can be made without larger trials and a control group. He does note a further phase 1 trial is already underway combining the experimental vaccine with checkpoint inhibitor immunotherapy, which is known to enhance immune system activity. The hope is the combination treatment will amplify immune responses.