Astrocytoma and glioblastoma are fast-growing brain cancers that often return after surgery. Survival for astrocytoma patients is generally four to five months. Medications that activate the body’s immune system, especially T-cells that fight cancer, help to stop most recurring cancers. This, however, does not apply to brain cancers such as astrocytoma, due to the tight layer of cells acting like a protective barrier around the brain called the blood brain barrier (BBB).
Invading the BBB
University of Southern California (USC) Keck Medicine researchers and three other sites nationwide, developed a method of breaking through the BBB making immune checkpoint inhibitors highly effective and providing patients with long periods of remission.
Clinical trial Phase 1/2b investigators have uncovered a minimally invasive therapy that destroys malignant tumor tissue and disrupts the BBB using pembrolizumab, an immune checkpoint inhibitor drug. Results of the study were published in Nature Communications. The patients (N-45) were in mid-to advanced stages of the disease. They received laser thermal therapy (LITT) then pembrolizumab and were alive eighteen months later as opposed to patients who received the standard treatment and surgery.
Dr. David Tran, Neuro-oncology chief and the study’s lead author, commented that trial results showed patients receiving LITT have few options. The new approach extends options and longer-term survival.
Breaking Through the BBB
Dr. Tran and his team relied on past research to show that heat produced by LITT disrupts the blood-brain barrier for weeks. That is just enough time for T-cells to target cancer cells. The trial involved those participating to either receive LITT or standard surgery and biopsy then pembrolizumab,
Patients who received LITT or surgery were monitored by MRI to locate the tumor in the brain, guide the LITT probe to the tumor then deliver the laser heat to the tumor where it is destroyed. As the heat destroys the tumor, surgeons are simultaneously working to ensure that healthy brain tissue has not been damaged. In addition, the heat disrupts the BBB and T-cells are then able to slide past it and into the blood.
Going Forward
The LITT and pembrolizumab combination was judged to be generally safe and also well tolerated. The USFDA recently cleared LITT in the treatment of several brain tumors Pembrolizumab received approval in the treatment of certain cancers.
