What’s New in Research for Childhood Brain and Spinal Cord Tumors?

There is always research going on in the area of brain and spinal cord tumors. Scientists and doctors are looking for causes and ways to prevent them, better tests to help characterize these tumors, and better ways to treat them.

Finding and testing for gene changes in brain tumors

In recent years, researchers have found some changes in genes, chromosomes, and proteins inside brain tumor cells that can be used to help predict a child’s outlook (prognosis) or help guide treatment. Some examples of changes that can now be tested for include: 

• IDH1 or IDH2 gene mutations
• Chromosomal 1p19q co-deletions
• MGMT promoter methylation

For children with medulloblastomas, doctors can now also test for other gene changes that can help show if they are likely to have a better outlook (and therefore might require less intensive treatment).

For more on these tests, see "Lab tests of biopsy specimens" in Tests for Brain and Spinal Cord Tumors in Children.

Researchers are also looking for other changes in tumor cells that might help guide treatment.

Imaging and surgery techniques

Recent advances have made surgery for brain tumors much safer and more successful. Some of these newer techniques include:

• Magnetic resonance spectroscopy (MRS). In this approach, described in Tests for Brain and Spinal Cord Tumors in Children, specially processed MRS information is used to make a map of important chemicals involved in tumor metabolism. This can help surgeons direct their biopsies to the most abnormal areas in the tumor. It can also help doctors direct radiation to the right areas and evaluate the effects of chemotherapy or targeted therapy.
• Diffusion tensor imaging (DTI), also known as tractography. This is a type of MRI test that can show the major pathways (tracts) of white matter in the brain. This information can be used by surgeons to help avoid these important parts of the brain when removing tumors. 
• Fluorescence-guided surgery. For this approach, the patient drinks a special dye a few hours before surgery. The dye is taken up mainly by the tumor, which then glows when the surgeon looks at it under special lighting from the operating microscope. This lets the surgeon better separate tumor from normal brain tissue. Researchers are now looking to improve on the dyes currently in use.
• Newer surgical approaches for some types of tumors. For example, a newer approach to treat some tumors in or near the pituitary (such as some craniopharyngiomas) is to use an endoscope, a thin tube with a tiny video camera lens at the tip. The endoscope is passed through a hole made in the back of the nose, which allows the surgeon to operate through the nasal passages and limits the potential damage to the brain. A similar technique can be used for some tumors in the ventricles, where a small opening in the skull near the hairline serves as the point of endoscope insertion. The use of this technique is limited by the tumor’s size, shape, position, and by how many blood vessels it contains.

Radiation therapy

Children's brains are very sensitive to radiation, which can lead to side effects if normal brain tissue receives a large dose, especially if the child is very young. Several newer types of radiation therapy now let doctors aim radiation more precisely at the tumor, which helps spare normal brain tissue from getting too much radiation. Newer techniques such as stereotactic radiosurgery, 3-dimensional conformal radiation therapy (3D-CRT), intensity modulated radiation therapy (IMRT), and proton beam therapy are described in Radiation Therapy for Brain and Spinal Cord Tumors in Children.

Clinical trials have shown that in some situations, using chemotherapy can let doctors use lower doses of radiation therapy without lowering the chance that treatment will be effective. Doctors are now trying to determine if even lower doses of radiation can be used and still give the same results.

Chemotherapy

New approaches may help make chemotherapy (chemo) more useful against brain and spinal cord tumors.

Adjuvant chemotherapy

In some children and infants with brain tumors, chemo is given right after surgery to either delay radiation therapy (particularly in infants) or to decrease the radiation dose needed to treat the tumor. This is known as adjuvant chemotherapy. Some studies are looking at whether giving prolonged chemo can help avoid the need for radiation therapy at all in certain cases.

High-dose chemotherapy and stem cell transplant

One of the main factors that limits the doses of chemo that can be given safely is its effects on the bone marrow, where new blood cells are normally made. A stem cell transplant allows higher doses of chemo to be given than would normally be possible. First, blood stem cells are removed from either the child’s blood or the bone marrow and are stored in a deep freeze. The child is then treated with very high doses of chemo. The blood stem cells are then thawed and infused back into the body, where they settle in the bone marrow and start making new blood cells.

Although some children with certain brain or spinal cord tumors (such as medulloblastomas) have responded well to this very intensive treatment, it can have serious side effects, and it is not yet known if it is effective enough to become a standard treatment. For now, most doctors consider this treatment experimental for brain and spinal tumors. Clinical trials are being done to determine how useful it is.

Improving chemotherapy drugs

Many chemo drugs are limited in their effectiveness because the tightly controlled openings in the brain capillaries, sometimes referred to as the blood-brain barrier, prevents the drugs from getting from the bloodstream to some parts of the brain tumor. Researchers are now trying to modify some of these drugs by coating them with tiny layers of fat (liposomes) or attaching them to molecules that normally cross the blood-brain barrier, to help them work better. This is an area of active research.

Getting chemotherapy directly to tumors

Some newer approaches might help doctors get chemo directly to brain and spinal cord tumors.

For example, in one method called convection enhanced delivery, small tubes are placed into the tumor in the brain through a small hole in the skull during surgery. The tubing extends through the scalp and is connected to an infusion pump, through which chemo drugs can be given. This can be done for hours or days and might be repeated more than once, depending on the drug used. This technique can also be used to get other, newer types of drugs into the tumor. This is still an investigational method, and studies are continuing.

Researchers are also looking at the possibility of using lasers or other means to disrupt the blood-brain barrier and allow drugs to more readily reach brain tumors.

Other new treatments

Researchers are also testing some newer approaches to treatment that may help doctors target tumors more precisely. The hope is to develop more effective treatments that cause fewer side effects. Although these treatment approaches are promising, most are still experimental at this time and are only available through clinical trials.

Targeted drugs

As researchers have learned more about the gene changes in tumor cells that help them grow, they have developed newer drugs that target these changes. These targeted drugs work differently from standard chemo drugs. Here are some examples of targeted drugs now being studied or in use:

• Everolimus (Afinitor) is a drug that targets mTOR, a protein involved in cell growth. This drug may shrink or slow the growth of subependymal giant cell astrocytomas (SEGAs) that can’t be removed with surgery.
• A small portion of low-grade gliomas have been found to have a change in the BRAF gene known as a V600E mutation, which can help them grow. Research has shown that drugs that target the BRAF protein (or related proteins) might be helpful in treating tumors with BRAF V600E mutations if other treatments are no longer working. The targeted drugs dabrafenib (Tafinlar) and trametinib (Mekinist) are now approved for use in treating these tumors, and other drugs are also being studied.
• Some types of medulloblastomas tend to have mutations (changes) in genes that are part of a cell signaling route called the sonic hedgehog (SHH) pathway. This pathway is crucial for the development of the embryo and fetus, but it can be overactive in some medulloblastoma cells. Drugs that target proteins in this pathway are now being tested against medulloblastoma in clinical trials.

Many other targeted drugs are already being used to treat other types of cancer, and some are being studied to see if they will work for brain tumors as well.

Angiogenesis inhibitors

Tumors have to create new blood vessels (a process called angiogenesis) to keep their cells nourished. Targeted drugs that attack these blood vessels are used to help treat some cancers, including some brain tumors in adults. Several drugs that impair blood vessel growth are now being studied for use against brain tumors in children.

Hypoxic cell sensitizers

Some drugs increase the oxygen content in the tumor, which makes tumor cells more likely to be killed by radiation therapy if the drugs are given before treatment. Studies are now looking to see if this affects treatment outcomes.

Immunotherapy

The goal of immunotherapy is to help the body’s own immune system fight the tumor.

Several types of vaccines are being developed against brain tumor cells. Unlike vaccines against infectious diseases, these vaccines are meant to help treat the disease instead of prevent it. The goal of the vaccines is to stimulate the body’s immune system to attack the brain tumor cells.

Early study results of some of these vaccines have shown promise, but more research is needed to determine how effective they are. At this time, brain tumor vaccines are available only through clinical trials.

Other types of drugs that affect the immune system are also being studied.

Therapeutic viruses

Researchers have done a great deal of lab work with viruses that reproduce only within brain tumor cells and then cause those cells to die, while leaving normal cells alone. Research using these viruses in humans with brain tumors is still in very early stages.