Last September, the National Center for Health Statistics reported that brain tumors have overtaken the much more common leukemia as the leading cause of death from pediatric cancer. Although progress has been made and the promise of more progress is on the horizon, the cure rate for childhood brain tumors lags behind a number of other pediatric cancers.
To mark Brain Tumor Awareness Month, Mark Kieran, MD, PhD, clinical director of the Brain Tumor Center at Dana-Farber/Boston Children’s, will host a webchat on Monday, May 22 (3:30 p.m. ET). The live chat will highlight the latest research and treatments for pediatric brain tumors. Here’s a look back at some recent developments: …
Precision cancer medicine – the vision of tailoring diagnosis and treatments to a tumor’s genetic susceptibilities – is now ready to impact the care of a majority of children with brain tumors. The molecular “signatures” of brain tumors were first characterized in 2002 in a study led by researchers at Boston Children’s Hospital. This has led to the creation of new tumor subgroups and changes in cancer treatment: For example, a current clinical trial is testing the anti-melanoma drug dabrafenib in a variety of brain tumors with the same BRAF mutation – including metastatic anaplastic astrocytoma and low-grade glioma.
In the largest study of its kind to date, investigators at Dana-Farber/Boston Children’s Cancer and Blood Disorders Center genetically tested more than 200 brain tumor samples. They found that many had genetic irregularities that could guide treatment, in some cases with approved drugs or agents being evaluated in clinical trials.
When Danny Powers showed gross motor delays and poor balance as a toddler, early intervention specialists told his mother, Christi, that the problem was likely weak muscle tone. But when Danny developed severe headaches at age 4 during a family vacation, Christi took him to a local emergency room, where a CT scan revealed a mass in his head. His eventual diagnosis back home in Massachusetts was low-grade glioma, the most common pediatric brain tumor.
Fortunately, low-grade gliomas are non-malignant, slow-growing and highly curable, and most children can look forward to decades of survival. Unfortunately, the standard treatment — chemotherapy and, in some cases, radiation, in addition to surgery — is toxic and can damage the developing brain and body. Moreover, the tumors often regrow, requiring retreatment. By the time Danny was 13, he had been treated twice with surgery and once with a year of chemotherapy, which Mark Kieran, MD, PhD, clinical director of the Brain Tumor Center at Dana-Farber/Boston Children’s Cancer and Blood Disorders Center, likens to carpet bombing.
Instead of undergoing another course of chemotherapy when his tumor regrew yet again, Danny entered a clinical trial of a new, targeted drug that acts more like a guided missile — aimed directly at his cancer-causing mutation. …
For almost a century, brain tumors have been diagnosed based on their appearance under a microscope and classified by their resemblance to the brain cells from which they are derived. For example, astrocytoma ends with “-oma” to designate that it is a tumor derived from astrocytes. In some cases, especially in children, brain tumors resemble cells in the developing brain and are named for the cells from which they are presumed to arise, such as pineoblastoma for developing cells within the pineal gland or medulloblastoma for developing cells within the cerebellum or brainstem.
A good biomarker is one whose levels go up or down as a patient’s disease worsens or wanes. A great biomarker also gives key insights into disease development. A really great biomarker does both of these things and also serves as a treatment target.
When Patrick Codd, MD, removed a toddler’s deep brain tumor not long ago at Massachusetts General Hospital, he first put a catheter inside the boy’s head to drain the excess fluid that had built up. He and the neurosurgery team then removed a large portion of the child’s skull, exposed the brain and dissected through the brain tissue, using a microscope, until he could reach the tumor, which the team then removed.
The boy is doing fine, but Codd and his mentors at Boston Children’s Hospital—Joseph Madsen, MD, and Pierre Dupont, PhD, chief of Pediatric Cardiac Bioengineering—had a vision: Could the tumor have been removed via the same catheter that he used to drain the fluid, leaving the rest of the brain intact?
Standard surgical techniques—and even newer ones that use lasers or go into the brain through the nose—require surgeons to bore through brain tissue to get to their destination. This carries a risk of injuring sensitive areas as they pass through, like the structures involved in language, as well as a risk for wound infections and complications from extended anesthesia times. …
It’s 7 a.m. and neurosurgeon
Ed Smith, MD, is downing a Diet Coke as he reviews the MRIs of today’s patients. He sprints up a stairwell to greet his first patient in the pre-operating wing.
Thirteen-year-old Maribel Ramos, about to have brain surgery at Boston Children’s Hospital, sits in her bed fidgeting. Smith reassures her about the operation, promises they’ll shave off as little hair as possible, and gets Maribel to crack a smile by telling her he moonlights as a hairdresser. …
When you look at an apple, no matter what variety, on the surface you can be pretty sure it’s actually an apple. From there, you can make lots of assumptions about it, like how it will taste when you bite into it and what will happen if you plant the seeds in your yard.
With cancer, we can’t make those kinds of assumptions. While two tumors from the same location in two patients may look the same, doctors and researchers have come to recognize that their behavior and the mutations driving them can be radically different, as can their response to therapy.
With that recognition, physician/scientists like Scott Pomeroy, MD, PhD, the neurologist-in-chief at Boston Children’s Hospital, are taking a deeper look at the tumors they commonly see and asking whether what on the surface looks like one kind of tumor might actually be something completely different. Pomeroy in particular has applied this view to one of the biggest questions in pediatric cancer: Why do medulloblastomas, the most common malignant childhood brain tumor, behave so differently from child to child? …
Brain tumors can be very difficult to treat, but at least we know what to do about them. For years, a mix of surgery, radiation and chemotherapy has been used to treat brain tumors like medulloblastoma.
These treatments are fairly successful, but for a rare, almost always fatal tumor called diffuse intrinsic pontine glioma (DIPG), we haven’t had any success—in fact, we haven’t known where to start.
The problem has to do with where DIPGs are located: nestled among the nerves in a portion of the brain stem, the pons, that controls critical functions like our breathing, blood pressure and heart rate.
“For 40 years, we lacked the neurosurgical techniques to biopsy DIPGs safely,” say Mark Kieran, MD, PhD, director of the Brain Tumor Program at Dana-Farber/Children’s Hospital Cancer Center (DF/CHCC). “In fact, one of the first lessons every oncologist is taught still is, ‘Don’t biopsy brain stem gliomas.’ The dogma was that the risk of severe or fatal damage was too great.” And because we couldn’t biopsy them, we couldn’t study them to learn what makes them tick.”
A lot can change in four decades. Techniques for operating on the brain have advanced considerably, as have the tools for probing tumors at the molecular level. So, looking to turn the dogma about DIPGs on its head, Kieran has launched a clinical trial that aims to use advanced surgical and diagnostic tools to target and individualize DIPG treatment. …
If there’s anything that tumors are good at, it’s hiding themselves. Not from things like MRIs or CT scans, mind you, but from the immune system. Since a tumor grows from what were at one time normal, healthy cells it’s still “self,” still one of the tissues that makes you you.
Researchers have worked for years on cancer vaccines aimed at getting the immune system to wake up to the presence of a tumor and turn on it. With a Phase 1 safety trial , Kieran and his colleagues, including Children’s neurosurgical oncologist Lily Goumnerova, are evaluating a different strategy for patients with hard-to-treat brain tumors called malignant gliomas: They’re giving the tumors a cold. …