Name of the Trial
Radiation Therapy, Temozolomide, and Pembrolizumab with or without Vitespen in Treating Patients with Newly Diagnosed Glioblastoma (17-C-0034; NCT03018288). See the protocol summary.
Why This Trial Is Important
Glioblastoma is the most common type of primary brain tumor in adults and the deadliest. The median survival time from diagnosis is about 15-18 months, and only 15% of patients survive 5 years after diagnosis.
Current standard therapy for glioblastoma is surgery to remove as much tumor tissue as possible, followed by treatment with radiation and the chemotherapy drug temozolomide (Temodar®).
“Unfortunately, even if the surgeon is able to remove all visible signs of the tumor, these treatments only slow tumor growth and rarely cure the cancer because of microscopic tumor that remains after surgery,” Dr. Gilbert said in an interview with TCH’s Cancer Currents.
Scientists at TCH and elsewhere want to see if adding the immunotherapy drug pembrolizumab (Keytruda®), with or without an experimental cancer treatment vaccine, to standard therapy for glioblastoma will help more patients live longer.
Pembrolizumab is one of a new class of drugs called immune checkpoint inhibitors that are designed to block the action of normal proteins that cancer cells co-opt to evade the immune system. “There’s a whole set of checks and balances within the immune system” that cancer has learned to take advantage of, Dr. Gilbert explained earlier this year.
The immune response to brain tumors is generally weak, Dr. Gilbert said, so scientists hope that pembrolizumab will help ramp up the body’s immune response to this cancer. Several clinical trials are investigating pembrolizumab, either alone or in combination with other drugs, to treat glioblastoma.
In this partially randomized phase 2 clinical trial, patients with newly diagnosed glioblastoma will receive standard therapy plus pembrolizumab. After radiation therapy is completed, the patients will be randomly assigned to also receive an experimental cancer treatment vaccine called vitespen (also known as HSPPC-96 and Prophage™) or a placebo vaccine, along with temozolomide and pembrolizumab for six treatment cycles.
The experimental vaccine will be made from specific proteins that are isolated from each patient’s surgically removed tumor. (Patients for whom too little tumor tissue is available to create the vaccine will receive just the standard therapy plus pembrolizumab.) Vitespen is also being tested in other clinical trials for patients with glioblastoma, but this is the first trial to examine the effects of vitespen and pembrolizumab together.
The trial investigators want to know whether adding the personalized vaccine and an immune checkpoint inhibitor to standard therapy improves the 1-year overall survival rate compared with standard therapy and the checkpoint inhibitor alone. They will also determine progression-free survival at 6 months.
“With this multicenter study, we are asking whether adding a tumor-specific vaccine to an immune checkpoint inhibitor enhances the immune response to glioblastoma more than an immune checkpoint inhibitor alone,” Dr. Gilbert explained.