New pathway discovered may improve success against an incurable type of children's brain cancer known as Diffuse Intrinsic Pontine Gliomas, reports a new study. The findings of the study are published in the journal Nature Communication.
The studysuggest that scientists have identified a unique way to disrupt the cellular process that contributes to Diffuse Intrinsic Pontine Gliomas (DIPG).
Earlier studies identified a genetic mutation called PPM1D, which is critical for cell growth and cell stress response as a contributor to DIPG. Previous efforts to directly attack the PPM1D mutation, however, proved futile in controlling DIPG.
Researchers found that mutated PPM1D silences a gene called NAPRT, which is key to the production of the NAD metabolite. With NAPRT unavailable, the cell switches to another protein needed to create NAD called NAMPT. By using a drug that inhibits the production of NAMPT, researchers found they could essentially starve to death those cancer cells with the PPM1D mutation.
"It is such a devastating disease, and we have been so stymied in our progress for new DIPG therapies. Many drugs have been tested with no success at all. These findings now offer new hope for children with this truly terrible disease," said another senior author Ranjit Bindra, M.D., Ph.D., Associate Professor of Therapeutic Radiology at the Yale Cancer Center, where he treats children with DIPG.
Researchers had long thought DIPG was a childhood version of adult brain tumors, and so similar treatments for adult gliomas were tested extensively in children and failed.
Frustration over the lack of effective therapy for DIPG led the researchers to take a different approach in the search for new drugs to treat this disease. They chose to look at the tumor in terms of its potential vulnerabilities, and thus began a year-long molecular journey to understand what role the PPM1D mutation played in altering cancer metabolism.
"When epigenetic silencing results were analyzed, we were gratified to discover that DIPG cells with the PPM1D mutation had created a vulnerability to a key enzyme for which small molecule inhibitors were already available," said Sen Peng, Ph.D., a bioinformatician in TGen's Cancer & Cell Biology Division, and one of the study's contributing authors.
While the number of patients affected in the U.S. is small -- about 300 annually -- DIPG is recognized as a profoundly tragic illness.
"Our study's potential translational impact should lead to clinical trials and renewed hope for these families who face such a difficult diagnosis for their child," said Charles Brenner, Ph.D., Chairman of Biochemistry at the University of Iowa, and an expert in nicotinamide adenine dinucleotide (NAD) metabolism. Dr. Brenner also was one of the study's senior authors.
Dr. Bindra said this study suggests that other cancers with PPM1D mutations, such as breast and gynecological cancers, could be similarly targeted.