A promising new treatment for patients with an aggressive form of brain cancer has been found to extend survival and longevity for years, a team of researchers from the United States revealed.

Doctors from University of California Los Angeles, UC San Diego and Cleveland Clinic injected patients who had recurrent glioblastoma, a hard-to-treat brain tumor, with a genetically engineered virus during the phase 1 study.

Glioblastoma is the most deadly of all kinds of brain cancers. Often, if the tumor recurs even after radiation and chemotherapy, there are few treatment options left and patients only have a few months to live.

Now, in the new study, experts found that among the 43 patients given the treatment called Toca 511 and Toca FC, survival increased by 13.6 months, compared to 7.1 months in an extended control.

Survival increased by more than two years for 42 percent of the participants, albeit with side effects.

The new report, which was led by Timothy Cloughesy of UCLA, is the first published data on the new type of modified virus called retroviral replicating vector (RRV).

RRVs are effective as they can deliver a gene with special function to a cancer cell, insert the gene and then debilitate the cell.

Here is how it works: Toca 511 selectively infects aggressively dividing cancer cells and transports a gene to activate an enzyme called cytosine deaminase (CD).

As the gene moves throughout the tumor, Toca 511 "orders" the cancer cell to produce CD. Once the cancer cells obey, they are prepared for the second step.

Patients then receive oral cycle of the antifungal drug Toca FC for seven days every four to eight weeks.

Toca 511 has already caused genetic changes in the tumor, and so this will allow infected cancer cells to turn Toca FC into the anticancer drug 5-fluorouracil (5-FU), which has been approved by the Food and Drug Administration (FDA).

As a result, cancer cells and immunosuppressive cells infected by both treatments are selectively killed, activating the immune system to recognize and target cancer cells while leaving healthy cells unharmed.

Meanwhile, Cloughesy says the use of RRVs shows promise in the development of new therapies for all kinds of brain cancer. It may also be applied in treatment for metastatic breast and colorectal cancers.

The research has now moved on to the phase 2 of the clinical trial called Toca 5. Details for phase 1 are published in the journal Science Translational Medicine.

Photo : W.Y. Inoue | Flickr

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