More than 10,000 children in the US will be diagnosed with cancer this year.
The idea of treating a child with a solid tumor based on their genetic traits falls into a field known as “precision medicine,” and it is a field that has gained increasing interest for the treatment of disease in adults.
According to the National Institutes of Health (NIH), “precision medicine is an emerging approach for disease treatment and prevention that takes into account individual variability in genes, environment, and lifestyle for each person.”
In simple terms, precision medicine is the opposite of the “one-size-fits-all” approach that has become the norm for the treatment of human disease. Instead, it refers to therapies that are tailored to each person.
In the case of a woman with breast cancer, for example, the patient may be treated based on the unique genetic mutations present in her breast tumor.
It is hoped that precision medicine will enable faster, more effective treatment for cancer and a wealth of other diseases.
But while the approach has gained acclaim as a feasible treatment strategy for adults with cancer, the development of personalized medicine for childhood cancers is lagging.
The barriers to precision medicine for childhood cancer
One factor that has been holding back precision medicine for childhood cancer is the inability to gather enough data on the genetic mutations that contribute to cancerous tumors in children.
Childhood cancers are far less common than adult cancers. This year, it is estimated that 10,380 children in the US under the age of 15 will receive a cancer diagnosis. For comparison, there will be more than 246,000 new cases of breast cancer alone diagnosed among women in the US this year.
It is obviously positive that childhood cancers are not more prevalent, but their rarity makes it harder for researchers to gather a sufficient amount of genetic data.
What is more, childhood cancers hold significantly fewer genetic mutations than adult cancers, primarily because children have been exposed to fewer environmental and lifestyle factors that can alter DNA.
Another barrier to precision medicine for pediatric cancer is that there are few targeted drugs – experimental and approved – available for children. Most drug companies focus on developing targeted therapies for adults, and for existing targeted drugs, current formulations or dosing guidelines are often unsuitable for children.
But it seems the idea of precision medicine for children with cancer may finally be gaining momentum.
Assessing the feasibility of genomic sequencing for pediatric cancer
In January this year, researchers of a study published in JAMA Oncology claimed their findings show genomic sequencing is viable for children with cancer and can be used to both diagnose and treat solid tumors.
The iCat study used genomic sequencing to identify gene mutations in the tumor samples of 100 young cancer patients.
The research – called the Individualized Cancer Therapy (iCat) Study – was led Dr. Katherine Janeway, clinical director of the Solid Tumor Center at Dana-Farber/Boston Children’s Cancer and Blood Disorders Center in Massachusetts.
Dr. Janeway and her team collected tumor samples from 100 cancer patients with a median age of 13.4 years.
All patients had visited one of four academic medical centers in the US between August 2012 and November 2013 for a relapsed pediatric solid tumor, and the patients were followed up for an average of 6.8 months.
The researchers used a number of sequencing techniques, including next-generation sequencing, that allowed them to assess the tumor samples for all known cancer mutations in 305 genes.
If the team identified any gene mutations in the tumor samples that were deemed “clinically actionable” – that is, a gene mutation for which experimental or approved therapies exist that can be given in doses and formulations suitable for children – then a treatment recommendation, or “iCat recommendation,” to the patient’s oncologist was made.
31% of pediatric patients had clinically actionable tumors
“We designed the study such that if we could make an iCat recommendation for 14% of participants, we could say that clinical sequencing was feasible,” says Dr. Janeway. “We exceeded this benchmark.”
The researchers were able to make a treatment recommendations for 31 of the 100 patients. Of these, three underwent the recommended treatment, although none of them responded.
For the remaining 28 patients, reasons for not receiving the recommended treatment included ineligibility, a good response to current therapy or death.
The team identified gene mutations in the tumors of a further 12 patients, which demonstrated either a predisposition to cancer and/or a change in cancer diagnosis.
Dr. Janeway and colleagues say their findings demonstrate the feasibility of using genome sequencing for pediatric solid tumors to help aid diagnosis and targeted treatment, and they note that theirs are not the first to do so.
On the next page, we further investigate how research is advancing the use of genomic sequencing in pediatric oncology, and how the pharmaceutical industry is hampering the progress of precision medicine.
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