New Immunotherapy Study for Glioblastoma
, by Kristin Odom, NCI-CONNECT Communications Editor
A clinical trial investigates immune checkpoint inhibitors with standard treatment in people with aggressive brain cancers to understand the immune system response and improve long-term outcomes.
Glioblastoma is the most common type of primary brain cancer. The cancer begins in astrocyte cells in the brain and is very fast-growing. The brain tumor cells can also suppress the immune system making it ineffective against the cancer. Therefore, people with glioblastoma or a variant called gliosarcoma have poor long-term outcomes.
Mark Gilbert, M.D., chief and senior investigator at NCI’s Center for Cancer Research, Neuro-Oncology Branch, is studying a new immunotherapy treatment to slow or stop the spread of cancer cells in people with glioblastoma and gliosarcoma and improve outcomes.
The clinical trial is testing if immune checkpoint inhibitors given with standard treatment results in an immune response in the blood and if that results in better outcomes than people who do not get a response. The trial will also evaluate a test that may help determine who is likely to get that response.
Immune checkpoint inhibitors are drugs that block proteins called checkpoints. Checkpoints are made by immune system cells, such as T cells, and some cancer cells. These checkpoints can keep immune responses from being too strong and T cells from killing cancer cells. By blocking checkpoints, T cells can better kill cancer cells.
“The primary goal of our new immune monitoring study is to determine whether the response in the blood is associated with a response in the brain tumor. This would suggest that there is benefit to getting an immune checkpoint inhibitor,” says Dr. Gilbert.
Understanding the Trial Design
There are many types of immune checkpoint inhibitors. The type that are most effective at treating cancers target proteins on T cells or cancer cells are called PD-1 and CTLA-4.
Previously, an NIH-led national trial showed that a combination of drugs – ipilimumab, which targets the proteins CTLA-4 and PD-1, and nivolumab, an immunotherapy treatment – is safe in patients with glioblastoma. “Knowing that this combination of drugs is well tolerated with expected side effects in brain tumor patients allowed us to move forward in planning our study using these immunotherapy drugs in this patient population,” says Dr. Gilbert.
Researchers in the Neuro-Oncology Branch are uniquely taking their new trial a step further by intensely monitoring the immune function of people with glioblastomas and gliosarcomas.
We believe there is a subgroup of tumor types that may show response to these immunotherapy treatments.
The new immune monitoring study evaluates if there is an immune response in the participant’s blood, which could mean that some of the immune cells will cross the blood-brain-barrier to effectively reach and treat the tumor. Then, doctors could predict which patients are likely to get an immune response. This could also avoid expensive and potentially toxic therapy to patients who would not get a response.
The clinical trial is for adults (age 18 or older) who are diagnosed with glioblastoma or gliosarcoma. Additional criteria are based on blood counts, and liver and kidney function, and importantly, patients cannot be on any steroid medication. Patients can enroll after they complete initial radiation therapy.
Participants get standard chemotherapy (temozolomide or temodar) taken orally at home for the first six months, plus the immune therapy (ipilimumab and nivolumab) given intravenous during the first four months, then nivolumab for 12 additional months. Participants visit the NIH in Bethesda, Maryland, for an evaluation, blood draws and treatments.
“There are quite a few visits in the first four months, but that is when we get the most activation of the immune system,” says Dr. Gilbert. Patients receive treatments every two weeks during the first four months, then monthly for a total of 16 months.
“We designed the study based on quality science and built-in cutting-edge techniques so that we better understand the immune response in patients with brain tumors. The study results should be a very important contribution to the field,” says Dr. Gilbert.