Translocation Testing Bolsters Personalized Treatments

Published in Hopkins Medicine - Spring/Summer 2021

Knowledge is power — particularly for cancers in the age of personalized medicine, says Johns Hopkins neurosurgeon Chetan Bettegowda, who notes that a growing number of tools are providing a deeper look inside tumor cells’ inner workings, giving insight that can shed light on prognosis and help doctors precisely target treatments.

The latest members of this armamentarium, he says, are translocation tests that can be performed at Johns Hopkins.

These tests identify rearrangements in genetic material that occur when a piece of one chromosome breaks off and fuses with another chromosome. Translocations are hallmarks of many types of cancers treated by Johns Hopkins’ neurosurgical service, including various types of gliomas, carcinomas and sarcomas. Identifying common translocations in these tumors can help providers understand the specific tumor subtype a patient has and might provide information on a patient’s short- and long-term prognosis.

More excitingly, Bettegowda says, for some tumor subtypes, translocation testing can identify rearrangements that can be targeted by newer medications.

And there are more benefits. “Historically, the only way we’ve been able to detect these translocations has been quite laborious, requiring a significant amount of time and effort to seek out potential rearrangements one by one. Patients often had to send samples, sometimes at significant personal expense, to outside companies for this service,” Bettegowda explains. “New technology has revolutionized this task, allowing us to identify many translocations at once.”

Patients can now access these tests through an order from their physicians at Johns Hopkins. Using a biopsy, the pathology department at Johns Hopkins will run one of three distinct panels to identify different types of fusions. One is an actionable fusion set, designed to recognize various types of translocations that can be treated with targeted drugs. Another is a carcinoma fusion set, which identifies translocations common to these tumors that arise in epithelial cells. The third is a comprehensive panel that searches for all known types of translocations — knowledge particularly useful for sarcomas, connective tissue cancers that tend to have few mutations but frequent fusions.

Besides benefitting current patients’ prognosis and treatment, the knowledge gathered from translocation tests is helping guide research efforts that could help those facing these cancers in the future, a boon in a field that is advancing quickly, Bettegowda says.