While childhood cancer is relatively uncommon, it’s still something far too many families face.
Globally, about 400,000 children are diagnosed with cancer each year, according to the American Childhood Cancer Organization.
While nearly 80% of children with cancer in the U.S. will be cured, many face lifelong quality-of-life challenges or medical complications that come as a result of their treatment.
Side effects from chemotherapy and radiation can vary widely from patient to patient, and even from one treatment to the next. Patients can experience anything from loss of appetite, constipation, bruising and mouth sores to puberty problems, hearing loss and life-threatening infection.
Immunotherapy in pediatric cancer treatment
Researchers at Texas Children’s Hospital are working to develop new, more effective therapies for childhood cancer. They’re also seeking to enhance current immunotherapy treatments and to find ways to integrate targeted therapy earlier in pediatric cancer treatment.
Immunotherapy is especially promising for childhood cancers because of the toxicities associated with traditional treatments like chemotherapy and radiation therapy.
According to Texas Children’s Hospital, using a patient’s own immune system to fight their cancer can specifically target their cancer cells and help avoid damage to normal tissues while improving cure rates without lifelong side effects.
Dr. Shoba A. Navai, Assistant Professor of Pediatrics in the division of Pediatric Hematology Oncology at Texas Children’s Hospital, is on the frontlines of immunotherapy research at the hospital. She said the doctors who are conducting the research are, simply put, harnessing the body’s immune system and using it to fight cancer in these young patients.
She, along with fellow researchers, are pioneers in developing ‘CAR’ T or NK-T cells -- supercharged immune cells that are genetically modified to target certain proteins on cancers that have otherwise been resistant to traditional therapies.
“Most of the new treatments we develop at Texas Children’s Hospital are in a category called cellular immunotherapy, which is where we take a patient’s immune cells and turn them back on to fight their cancer,” Navai said. “One of our main focuses is called CAR T-cell therapy, which is where we collect white blood cells (T-cells) from the patient’s blood, take those to the lab where we purify them, and then we genetically engineer them using a specialized virus to deliver new DNA into the cell.”
Navai said this DNA codes for a new molecule, called a CAR, that specifically targets a protein found on a cancer cell.
“When we genetically engineer cells that express this CAR, we can make billions of them, freeze them and, when they’re ready to be used, we give them back to the patient through an IV,” she said.
Navai, who, along with running clinical trials, takes direct care of patients with solid tumors, said these CAR T-cells can also be delivered directly into the brain in patients with brain tumors to assist them in getting to the tumor more easily.
“Solid tumors have a lot of defenses,” Navai said. “When a tumor is being attacked by an immune cell (like a CAR T-cell), the tumor sends out many signals that trick the T-cells into turning off.”
This means those cancer-attacking cells are losing their ability to attack the tumor earlier on in the process.
”One strength of our center is that we’re focused on treating solid tumors, which are more challenging,” Navai said.
Part of the research she is doing uses strategies to sustain the longevity of the T-cells and to counteract these tumor defenses. It’s promising research, and doctors are confident they will continue to find new ways to fight the tumors.
“With our collaborative research and clinical teams, we are going to develop more ways to successfully overcome these obstacles,” Navai said.
Viral infections
In addition to cancer cells, immunotherapies can also be used to target viral infections in patients with cancer. Navai said Texas Children’s Hospital has a group that works on virus-specific T-cells, which is another type of cellular immunotherapy.
She said that patients who have no immune system after having bone marrow transplants are susceptible to many common infections, but those common illnesses can become life-threatening to these patients. Unfortunately, she said, there currently aren’t highly effective anti-viral drugs to treat these patients.
That’s where T-cell immunotherapy is showing promising results.
“Similar to how CAR T-cells can fight cancer, virus-specific T-cells can treat viral infections in bone marrow transplant recipients,” she said, adding that the patients can get quite sick after transplant. “Researchers in one recent trial at Texas Children’s Hospital gave T-cells that target six different viruses to patients who had life-threatening infections after transplant.”
The therapy was extremely effective.
“The overall response rate was 95% within six weeks of getting the infusion, with a 97% reduction of the amount of virus detectable in the blood,” Navai said.
Side effects
Chemotherapy and radiation, as mentioned above, can have some impactful and long-lasting side effects.
Navai said that while immunotherapy can have some of its own side effects, the cellular therapies generally don’t cause serious long-lasting effects like chemotherapy can.
“We try to design these therapies in a way that only targets the cancer,” she said. “The main side effects of immunotherapy are inflammation or flu-like systems. Sometimes when that gets severe, patients can get very ill, but we have many tools to reduce symptoms and prevent them from getting out of control. For example, we have some medications that can block inflammation in a way that doesn’t harm the CAR T-cells. If they occur, these side effects are generally only temporary.”
The future of immunotherapy
While there is still much to learn and overcome, the future of immunotherapy looks promising.
“If these therapies are successful, the hope is that they would reduce the need or replace chemotherapy,” Navai said. “In the setting of blood cancers like leukemia and lymphoma, we may see these therapies moving up into frontline treatment. On the solid tumor and brain tumor side, I hope they will be frontline therapies one day, as well, but it may take a bit longer. I envision that, through our research, we are going to learn much more about what’s happening inside the tumors to better understand how to counteract their defenses. As we gain that understanding, we are fully equipped and ready to translate those findings into meaningful new therapies for these patients.”
To learn more about pediatric cancer research being done at Texas Children’s Hospital, click or tap here.