Glioblastomas are the most common type of brain tumors in adults. They’re difficult to treat due to their location, making them one of the deadliest cancers. The tumors are aggressive, forming new blood vessels and growing rapidly and they can also use connection fibers to spread to the other side of the brain. Treating glioblastomas is difficult, as surgery can be impossible depending on the location within the brain and few drugs can cross the blood-brain barrier to treat the tumors. 

Recently, scientists at Cedars-Sinai in Los Angeles created a treatment by combining an immuno-oncology drug and a polymer-based delivery system that is capable of crossing the blood-brain barrier. In the study, researchers tested the drug combination in mice with gliblastomas. The study’s results, published in Nature Communications, showed that the treatment, called nano-immunotherapy, was able to cross the blood-brain barrier and stopped the tumor cells from multiplying. The polymer delivered two immune checkpoint inhibitors, blocking either CTLA-4 or PD-1. When injected into the mice’s bloodstream, the drugs were able to cross into the tumor cells and treat them, but didn’t affect health brain tissue. 

Past research has shown that brain tumors are able to suppress immune attacks with macrophages and T regulatory cells (Tregs). The researchers at Cedars-Sinai found that after they treated the mice with nano-immunotherapy, the checkpoint inhibitors blocked Tregs and macrophages, allowing the tumor-killing cells to treat the tumors. 

Additional preclinical trials are needed before the nano-immunotherapy is ready to be tested on humans, but Cedars-Sinai’s Julia Ljubimova, lead author of the study, is optimistic about the results. 

“The horizon for treatment of brain cancer is getting clearer,” she said. “We hope that by delivering multifunctional new-generation drugs through the blood-brain barrier, we can explore new therapies for many neurological conditions.”