In one of the first trials of personalized vaccines for cancer, the European-funded Glioma Actively Personalized Vaccine Consortium (GAPVAC) is about to launch a Phase 1 clinical trial for patients with glioblastoma, the most aggressive of brain cancers.
The goal of nearly all cancer treatments is honing in on antigens, the target structures on tumors, in order to kill only the cancer cells. One of the best strategies in developing precision treatments like these personalized vaccines, scientists believe, is to tailor the drug to the specific tumor antigens of the individual.
For each patient in the study, researchers will collect relevant genetic information from their tumors as well as their immune system and based on this information will administer two vaccine "cockatails." The first will contain previously-identified peptides relevant to the general treatment of glioblastoma. At least 72 of these peptide targets have been isolated and manufactured and are ready to be vaccinated into patients.
The second cocktail contains the personalized pattern of peptides expressed by the individual's tumor.
"A patient may express 20 of these 72 targets on their tumor, for example," said Dr. Harpreet Singh during an October symposium on Immuno-Oncology in Geneva, Switzerland. "If we find that the patient's immune system can mount responses to five of the 20 targets, we mix five peptides and give them to the patient."
Singh cites the use of trastuzumab, or Herceptin, in the treatment of breast cancer, as one of the first steps medicine took to personalized cancer treatment a decade ago. Originally, Herceptin was given to all breast cancer patients, Singh said, but its efficacy was limited to just 20 percent of cases. In a nationwide clinical trial 10 years ago, herceptin was found to be particularly effective for the subset of breast cancer victims who tested positive for the HER2 oncogene.
"...the personalized aspect is just based on the low abundance of HER2, the target," Singh said.
The Actively Personalized Vaccine, or APVAC, which Singh and his team are going to be studying in the clinical trial, is taking the science of personalized medicine one step further. And the possibilities, he believes, are profound.
"Personalization is not limited to vaccines but is a general principle that could be applied to cancer immunotherapy more broadly," Singh said. "We are starting with vaccines, but we are also thinking about how to use personalized antigens in adoptive cell therapy."