Immunotherapy can effectively treat patients with recurrent glioblastoma

In recent years, immunotherapy has become increasingly popular in the treatment of cancer, a method of killing cancer cells using the body's own immune system. Among them, immunotherapeutics have been shown to be helpful in the treatment of patients with advanced or metastatic cancer.

However, for glioblastoma, these drugs do not show any benefit. Glioblastoma is a malignant invasive brain tumor. Patients with glioblastoma survive less than 15 months after diagnosis, even brain surgery, radiation therapy, and chemotherapy. More than 90 percent of patients will relapse after more than two years of survival after the first treatment. Unfortunately, these patients are often ineligible for second brain surgery, because recurrent tumors are resistant to chemotherapy and radiation. On average, most people with recurrent glioblastoma can only live for 6 to 9 months.

Research led by the University of California, Los Angeles, has shown that preoperative immunotherapy drugs are more effective than postoperative medication for patients with recurrent glioblastoma.

The study, published in Nature Medicine, revealed for the first time that pembrolizumab is an immunological checkpoint inhibitor drug sold under the trade name Keytruda, which is effective in treating patients with recurrent glioblastoma.

Pembrolizumab is a humanized antibody that cuts off the protection of cancer cells by blocking the checkpoint protein called PD-1 (programmed cell death 1), allowing the immune system to destroy cancer cells. Cancer cells typically use PD-1 to block T cells. However, binding the inhibitory protein to checkpoint inhibitor drugs like pembrolizumab permits the immune system to better attack cancer.

The trial was conducted at seven medical centers in the United States and evaluated 35 patients with recurrent and surgically resectable glioblastoma, which means that the tumor can be surgically removed. Sixteen of them received pembrolizumab before surgery and 19 were subsequently treated with medication.

Patients who were given the drug before surgery had an average survival of 417 days, and patients who received the drug after surgery had an average survival of 228 days. It almost doubled the survival time of these patients. 

This result is very encouraging, and it is the first suggestion that immunotherapy can help patients with malignant brain tumors prolong life and help prevent future recurrence.

It is possible to activate T cells in cancer patients with previously impaired tumors by performing immunotherapy before surgery; on the contrary, after surgery, the drug does not stimulate the patient's T cells because these T cells are removed along with the tumor.

This finding could be important because the treatments of glioblastoma almost have not any significant advances over the past two decades. And it may be a step toward developing new biomarkers for the disease.

These data may provide a better understanding of the mechanisms by which some patients develop a significant immune response to this therapy, while others do not. It also helps us determine which combination of drugs is most successful for each patient.

The team is now testing immunotherapy with a combination of vaccines and other checkpoint inhibitors.