Immune therapy for brain tumors: A new promising avenue

Olivier Rixe, MD, PhD, Associate Center Director for Clinical Research at the UNM Comprehensive Cancer Center, serves as a National Principal Investigator for these clinical trials. He is working closely with a team of physicians at the UNM Cancer Center to conduct these trials: M. Omar Chohan, MD, a neurosurgeon who specializes in surgery for tumors of the brain and spinal cord; Gregory Gan, MD, PhD, a radiation oncologist who is an expert in the radiation therapy of brain tumors; and Yanis Boumber, MD, PhD, a newly recruited medical oncologist to the UNM Cancer Center who is an expert in cancers of the lung, brain and spinal cord, and early phase clinical trials.

The clinical trials test the combination of temozolomide and indoximod. Temozolomide kills cancer cells by damaging their DNA, but cancer cells can become resistant to it. Indoximod is a new immunotherapy drug made by NewLink Genetics, Inc. It disrupts a cellular process that cancer cells use to hide from the immune system and allows the immune system to recognize and attack the cancer. Half to 90 percent of glioblastoma cells use this cellular process so indoximod helps a patient's own immune system to find and attack their tumors.

Rixe and his colleagues presented their promising results at the Society for Neuro-Oncology Annual Scientific Meeting. They reported that four out of the 12 people in the phase 1b clinical trial responded strongly to the drug combination; their cancers did not grow for six months or more. All 12 people in that trial had already become resistant to standard therapies. They also reported that 40 people have joined the phase 2 trial so far; they are planning for 132 people to eventually join. Of these 40, nine have been on the drug combination for six months or more and seven of these nine are responding to the treatment so far.

"This is one of the first clinical trials testing an immune checkpoint inhibitor in glioblastoma," says Rixe. "It shows that indoximod is the first such therapy to produce an objective response in glioblastoma, an important milestone in the treatment of this serious condition."