NEW YORK – Molecular tumor profiling can uncover clinically relevant or targetable alterations in a significant subset of tumors from pediatric or young adult cancer patients, new research suggests.
"By providing a more accurate diagnosis or identifying a targeted therapy, molecular tumor profiling significantly impacts the care we provide," senior author Katherine Janeway, a researcher at Harvard Medical School and clinical genomics director at the Dana-Farber/Boston Children's Hospital, said in a statement. "The result is cancer treatment that is more effective and, in some cases, has fewer side effects."
Although US Food and Drug Administration-approved targeted tumor sequencing tests have already been incorporated into practice and insurance coverage guidelines for adult cancers in the US, the authors explained, pediatric cancer cases have only rarely been considered in trials informing such approvals.
"[T]here are no national coverage determinations or practice guidelines regarding [molecular tumor profiling] for pediatric solid malignancies," the authors noted in Nature Medicine on Thursday. "The situation in the United States is not unique, with regulatory approvals and consensus guidelines regarding multigene [next-generation sequencing] panel tests focused on adult cancers also existing in Europe and Asia."
As part of a prospective observational study called iCat2/genomic assessment informs novel therapy (GAIN), researchers at a dozen pediatric oncology centers performed targeted OncoPanel sequencing on one or more extracranial tumor samples for each of 345 children or young adults, ranging in age from infancy to almost 28 years old, with newly diagnosed, treatment refractory, or relapsed cancers. For a subset of cases, they also assessed RNA using tests including targeted fusion panels or transcriptome sequencing.
The team's results suggested that targetable molecular alterations are present in a significant subset of pediatric tumors. The analyses led to clinically relevant alterations in 298 of the cases, and 240 of the pediatric or young adult patients had alterations that were amenable to molecularly targeted therapies. The genomic data also offered diagnostic or prognostic clues for a subset of the cases.
"The results support the development of management guidelines and insurance reimbursement determinations addressing [molecular tumor profiling] with targeted panel tests in advanced pediatric solid malignancies," the authors suggested. "Given diagnostic significance in 61 percent of patients and real-time clarification of diagnostic classification in 5 percent of patients, performing [molecular tumor profiling] early in the disease course should be considered."
Within a group of 29 pediatric cancer patients who received molecularly targeted treatments, for example, the investigators saw objective responses in nearly one-quarter. They noted that gene fusions identified in tumors appeared to be particularly informative in cases with targeted treatment responses.
Fusions were the prevalent mutation type among the diagnostically informative variants, for instance, and they served as drug targets in almost all of the tumors that responded to molecularly targeted treatments.
"It's an exciting time because there are so many new drugs that can target these fusions and we have new tests that can reliably detect them," first and corresponding author Alanna Church, a researcher at Harvard Medical School and associate director of molecular pediatric pathology at BCH, said in a statement.
Even so, she cautioned that "there are patients who aren't getting access to these tests because they are not being reimbursed consistently," and emphasized the importance of broadening molecular profiling access "for every child with a solid tumor."