Scientific research have used a combination of gene therapy and chemotherapy drugs to increase a patient's tolerance for cancer medication and boost their effectiveness against the attack of brain cancer, while also protecting healthy cells from the devastating their effects.
The study was conducted on patients with glioblastoma, a type of cancer where less than half of the affected patients are expected to live for a year. Dr. Hans-Peter Kiem, stem cell transplant researcher from Fred Hutch, led the research and expects that this gene therapy with stem cells could potentially be a protocol that can be used with other types of malignant tumors. Over the past year, treatments and trials had to be suspended due to a shortage in the key drug component O6-benzylguanine, or O6BG, but now researchers are getting ready to move patients into the next phase of the trials.
The primary treatment for glioblastoma is temozolomide, or TMZ, but the brain tumors of patients with this disease produce the protein methylguanine that makes them resistant to the effects of TMZ. O6BG can undo the resistance but its combination with TMZ has a potentially deadly side effect.
By genetically inserting the engineered TMZ-O6BG combination directly into the patient's cells, Dr. Kiem and his team was able to shield them from the destructive effects of the combination drug, allowing it to target the cancer cells instead. This method also increases the tolerance of the patient for the chemotherapy. Most patients with brain cancer can only normally endure one to two sessions of chemotherapy, but with this type of gene therapy, one research subject was able to go through nine sessions.
Prior to the study, subjects were also injected with an additional drug, Carmustine, which conditioned the patients before the administration of the gene-modified blood cells. According one of the co-researchers, Dr. Jennifer Adair, " the drug helped the patients' bodies accept and use the gene-modified blood cells, but also treated any residual brain tumor. The gene therapy might not have worked without the conditioning."