While the genetic mutations driving adult cancers can sometimes be targeted with drugs, most pediatric cancers lack good targets. That’s because their driving genetic alterations often create fusion proteins that aren’t easy for drugs to attack.
“This is one reason why it is notoriously hard to make targeted drugs against childhood cancers — their cancer-promoting proteins often lack good pockets for drugs to bind to,” says Kimberly Stegmaier, MD.
Our blood carries tiny amounts of DNA from broken-up cells. If we have cancer, some of that DNA comes from tumor cells. Studies performed with adult cancers have shown that this circulating tumor DNA (ctDNA) may offer crucial clues about tumor genetic mutations and how tumors respond to treatment.
Brian Crompton, MD, with colleagues at Dana-Farber/Boston Children’s Cancer and Blood Disorders Center and elsewhere, is now working to bring ctDNA “liquid biopsies” to pediatric solid tumors as well. The researchers hope that these blood tests will eventually improve early detection, choice of treatment and monitoring of young patients with these diseases without having to sample the tumor itself. …
Screening a class of recently-developed drug compounds — so-called “CDK inhibitors” capable of blocking CDK7/12/13 proteins — against hundreds of different human cancer cell lines, researchers at Dana-Farber/Boston Children’s Cancer and Blood Disorders Center have found that CDK12 inhibitors pack a particularly lethal punch to Ewing sarcoma, a rare cancer typically affecting children and young adults.
Some individuals were entirely cured of the disease
“Now, in mice, we’ve shown that Ewing sarcoma cells die if CDK12 is knocked out genetically or chemically inhibited,” Stegmaier says. What’s more, her team has discovered that CDK12 inhibition can be combined with another drug, called a PARP inhibitor, to double down on Ewing sarcoma cells.
The revelation that CDK12 inhibition can kill Ewing sarcoma cells brings a surge of hope to the field of pediatric oncology, which has long been challenged to find new drugs against childhood cancers. …
The war on pediatric cancer hasn’t been going so well in the past couple of decades, says Timothy Triche, MD, PhD, a cancer researcher at Children’s Hospital Los Angeles. The existing intensive chemotherapy regimens carry a lot of “unfortunate baggage” for children in terms of lifelong morbidity, and haven’t brought about a tremendous change in outcomes, he says.
“We really don’t have a lot of new drugs, if any, and we really don’t have new targets,” he said at Boston Children’s Hospital’s Global Pediatric Innovation Summit + Awards last month. “Underlying this is the fundamental problem that we don’t understand a lot more about childhood cancer than we did before.”
In a Discovery Roundup highlighting four big ideas in pediatric care, Triche made the case for targeting the genome’s “dark matter” — the vast number of RNAs made from the genome that do not code for proteins. …
The fact that childhood cancer is, thankfully, rare belies the fact that it is the leading cause of disease-related death in U.S. children age 1 to 19. The number of people with a direct stake in expanding research into pediatric cancer is quite large, well beyond the small number of children with cancer and their families. Not only are the life-long contributions of children cured of cancer enormous, but understanding cancers of young children could also hold the key to understanding a broad range of adult cancers. The time is ripe to allocate more resources, public and private, to research on pediatric cancer.
In an age of increased understanding of the genetic basis of diseases, one thing is striking about many childhood cancers. They are relatively “quiet” cancers, with very few mutations of the DNA. Young children haven’t lived long enough to acquire the large number of mutations that create the background “noise” associated with years of living. This makes it much easier to pinpoint the relevant genetic abnormalities in a young child’s cancer.
Add to this the growing realization that biology, including how various tumors use common “pathways,” is a major factor in how the cancer responds to treatment. Thus, a mechanism that’s relatively easier to observe in the cancers of young children could help scientists understand cancers in adults, in whom the same mechanism is hidden amid the clutter of mutations acquired over a longer life. …