Pharmacogenomic Results Clear to Young Cancer Patients’ Families

LAS VEGAS — Families who received the results of pharmacogenomic testing for their children at one center understood the results they received but didn’t often share the test results with other outside providers, a survey showed.

Among 128 family members surveyed on their perceptions of pharmacogenomic testing, 90% of those who said they received results endorsed understanding the report from reading it on their own, Rachael Stone, PharmD, a clinical pharmacogenomics resident at St. Jude Children’s Research Hospital in Memphis, Tennessee, reported in a poster presentation at the Midyear American Society of Health-System Pharmacists meeting.

“I was pleasantly surprised by their independent understanding of pharmacogenomic results, because it is a more complex thing that not a lot of us learned about in school,” Stone told MedPage Today.

But 75% of guardians said they hadn’t shared the test results that could alert providers to drugs that would interact with genetic variations with any providers that might be caring for their child outside of St. Jude. Only 19% said they had done so, and 6% said they didn’t remember or know.

At the center, guardians receive the results in a patient portal for their child and can navigate to descriptions of any of the 14 pharmacologically-relevant genes evaluated. They can then read more about, for example, enzymes that the gene is responsible for and how the enzyme could affect the metabolism of certain medicines.

Of those that took the survey, 70% said their child had not needed a modification in therapy based on the pharmacogenomic testing, while 2% said they had needed to modify therapy and the remaining 28% said they weren’t sure.

That so many guardians weren’t sure if their child’s treatment had changed as a result of gene-drug interactions revealed by the testing could be both a positive and a negative, Stone said. “Maybe that means we caught the change before we even prescribed medication. Or it means that we just weren’t explaining well enough the things that we’re doing because of it. So it’s a double-edged sword.”

She noted that if parents weren’t aware a change was made to their child’s drugs, the child likely hadn’t experienced any adverse effects from a gene-drug interaction. At the same time, the parents might also be less likely to then share the testing information with other providers.

Stone explained that a high-risk phenotype shown in testing could be for a drug the child wasn’t currently taking, and thus wouldn’t prompt a change in treatment but would be available in the electronic health record (EHR) for future reference. For example, testing of a patient’s CYP2C19 gene could reveal a high-risk phenotype, or highly active CYP2C19 enzymes that could rapidly break down drugs like antithrombotic clopidogrel, voriconazole for fungal infections, and some depression medication. That kind of information, she said, would be good for other physicians to have.

The results moved St. Jude to hire another person who would educate guardians on the importance of sharing results with other providers.

Of the survey respondents who didn’t share results with other physicians, 32% didn’t have the results or didn’t know how to access them, 27% hadn’t seen other providers since testing, 22% indicated they forgot or it hadn’t occurred to them, 15% didn’t consider it necessary, and 4% gave no reason.

Some providers and researchers have expressed mixed opinions on the usefulness of pharmacogenomic testing, both because of the limited data on outcomes and because of the difficulty in communicating the results.

But Stone said this program has benefits for the St. Jude population in particular. “Our kids get a lot of meds sometimes, and so they might be exposed to certain medications that the general population wouldn’t be,” she said.

Fully 95% of the patients enrolled in the larger pharmacogenomic testing program did end up having at least one high-risk phenotype. Stone noted a study by a former resident finding that 95% of providers did act on EHR alerts that warned them of drug-gene interactions.

Her group’s study surveyed participants in a larger St. Jude protocol called PG4KDS, which tests all enrollees for variations in genes that could affect drug therapy. PG4KDS has enrolled some 7,000 patients so far, with a median age of 8 years. Patients and families also receive general education about pharmacogenomics and its implications for treatment. The survey was initially sent to 523 families of patients.