There is encouraging news from Cedars-Sinai Medical Group – 50% of patients participating in an experimental treatment for aggressive brain tumors have survived longer than 5 years since diagnosis.

Presenting their findings at the Fourth Quadrennial Meeting of the World Federation of Neuro-Oncology in San Francisco this month, the researchers reported eight of the original 16 participants in the study had defied the odds by surviving 5 years.

The original trial was testing a new immune system therapy against the most malignant form of tumor – glioblastoma multiforme.

According to the American Brain Tumor Association (ABTA), glioblastomas are particularly troublesome as the cells can reproduce quickly and are supported by a large network of blood vessels.

ABTA estimates that 17% of all primary brain tumors are glioblastomas and notes that their frequency increases with age, affecting more men than women.

The Cedars-Sinai study participants signed up for a new trial testing the safety of the ICT-107 vaccine, which alerts the immune system to the presence of cancer cells and triggers a tumor-killing response. The vaccine targets six antigens involved in the development of the cancer cells.

After receiving conventional treatment for the tumor – surgery to remove as much of the tumor as possible, followed by radiation and chemotherapy – study participants also received a vaccine three times at 2-week intervals after radiation and chemotherapy.

According to the information presented at the meeting, seven of the original participants are still living, with length of survival ranging from 60.7 to 82.7 months after diagnosis.

Six of the patients were also “progression-free” for more than 5 years, meaning the tumors did not return or need more treatment during that time.

Four participants still remain free of disease with good quality of life at lengths ranging from 65.1 to 82.7 months following diagnosis. One patient who remained free of brain cancer for 5 years died of leukemia.

The researchers explained that the study showed median overall survival of 38.4 months. Typically, when tumor-removal surgery is followed by standard care, median length of survival is about 15 months.

Median progression-free survival – the time from treatment to tumor recurrence – was 16.9 months at study’s end. With standard care, the median is about 7 months.

The Cedars-Sinai team explained that all eight long-term survivors had tumors with at least five antigens, 75% had tumors with all six, and 100% had tumors with at least four antigens associated with cancer stem cells – cancer-originating cells that appear to help tumors resist radiation and chemotherapy, and even regenerate after treatment.

Dr. Surasak Phuphanich, director of the Neuro-Oncology Progam at the Cochran Brain Tumor Center, says:

Our findings suggest that targeting antigens that are highly expressed by cancer stem cells may be a viable strategy for treating patients who have glioblastomas. Long-term remission of disease in this group of patients was correlated with the expression of cancer stem cell tumor-associated antigens.”

The vaccine is tailor-made for each patient using dendritic cells taken from their own white blood cells. Dendritic cells are one of the immune system’s most powerful antigen-presenting cells – cells that enable the immune system to identify invaders.

Researchers grow the dendritic cells in a laboratory with synthetic peptides of the six target antigens – essentially training the cells recognize these antigens as invaders. These new cells are then re-introduced to the patient, where they will hunt down and destroy any lingering tumor cells.

Based on the success of the trial so far, the ICT-107 vaccine has entered Phase II testing with a multicenter, randomized placebo-controlled trial that began in 2011.