Allison Martin, M.D. rarely shies away from a challenge. Not only has she chosen to specialize in pediatric brain cancer, one of the most complex and aggressive forms of cancer that plague children. She is also working to introduce immunotherapy as a way to treat pediatric brain cancers—an experimental method that, not long ago, was considered unthinkable by many in the field.
Dr. Martin recalls that, as a medical student, many researchers in her field expressed doubt that immunology would ever be used to fight brain cancer. She remained undeterred. In fact, when it came time to seek oncology training she intentionally sought out a forward-thinking institution aligned with her goals to one day apply immunotherapy to pediatric oncology patients. “When I came to Hopkins, the potential of using immunotherapy for brain tumors was really taking off,” Dr. Martin says.
While she is eagerly invested in developing immunotherapy modalities to fight pediatric brain cancer, Dr. Martin is well aware of the unique challenges inherent in applying new therapies to this disease. One is the presence of the blood-brain barrier, which prevents substances from entering the brain that it deems potentially injurious. Moreover, the brain contains several delicate structures that, in children, haven’t been fully developed. This factor adds another layer of caution in a research milieu that proceeds with pediatric studies only after a given agent has been found safe and effective in adults. But despite the long road to studying and implementing immunotherapy that lies ahead, Dr. Martin is heartened by the progress made in pediatric brain cancer over the past several decades.
“Treatment certainly has come a long way since the 1970s, when radiation and surgery were the primary treatment modalities available,” she says. With the standard addition of chemotherapy, we have been able to greatly reduce the amount of radiation needed for a cure—which is so important for young brains still under development,” she says.
But, explains Dr. Martin, 20 to 30 percent of pediatric brain cancer patients relapse and run out of treatment options. “We’re just starting to understand why that is,” she says. She and her colleagues believe it has to do with cancer’s ability to ‘outwit’ the body’s immune system.
Consequently, Dr. Martin hopes that immunotherapy eventually will be added to the repertoire of treatment options available to pediatric brain cancer patients. Already, some of her Hopkins’ colleagues are conducting groundbreaking work in the field of immunotherapy, including Michael Lim, M.D., director of Hopkins’ Brain Tumor Immunotherapy program, and Charles Drake, M.D., Ph.D., co-director of the division of Immunology for the Kimmel Cancer Center at Johns Hopkins. Thanks to these pioneering leaders, Hopkins researchers are studying the potential therapeutic ability of checkpoint inhibitors—drugs that prevent cancer cells from evading the body’s natural immune response.
Although Dr. Martin recognizes that the day is a long way off when a child with brain cancer will be treated with immunotherapy, the notion is never far from her mind. “Nothing is more motivating than having a patient with brain cancer in front of you. It keeps you going back to the lab, to continue to brainstorm,” she says, adding, “My hope is that in the next 30 years immunotherapy will be part of our standard approach and it will further reduce the toxicities suffered by today’s patients.”