In a paper published by Banerjee et al in JAMA Network Open, researchers reported that genetic testing is cost-effective and beneficial for newly diagnosed patients with metastatic gastrointestinal stromal tumors (GIST), a type of soft-tissue sarcoma that develops in specialized nerve cells in the wall of the digestive system, most often occurring in the stomach or small intestine.
Imatinib for GIST
GIST is frequently driven by oncogenic KIT variations, and imatinib, which targets KIT, is often used to treat patients with metastatic disease. However, studies on the molecular biologic traits of GIST have found that patients may respond differentially to imatinib dosage based on the KIT exon with a variation.
To determine which patients with GIST may be most responsive to treatment with imatinib, the National Comprehensive Cancer Network® suggests that patients undergo genetic testing to identify each individual’s tumor mutations; yet only 30% of patients have genetic testing at the time of diagnosis, likely due to concerns over cost and utility of testing, said senior study author Jason Sicklick, MD, Professor of Surgery in the Division of Surgical Oncology at University of California, San Diego School of Medicine.
“We recommend that all patients with a new diagnosis of metastatic GIST undergo genetic testing prior to the initiation of first-line chemotherapy,” said Dr. Sicklick, who is also a surgical oncologist and Co-Leader of the Sarcoma Disease Team at Moores Cancer Center at UC San Diego Health. “In doing so, those who are unlikely to benefit from imatinib can be given a treatment better suited for their individual tumor.”
“Genetic testing is cost-effective, as it allows clinicians to prescribe chemotherapy in a tumor-specific manner. Patients who would not benefit from imatinib because of primary tumor resistance are given alternative therapy,” said first study author Sudeep Banerjee, MD, who contributed the research while in the Sicklick lab at Moores Cancer Center and who is now Chief Resident at the David Geffen Medical School at the University of California, Los Angeles. “Avoiding ineffective treatment and reduced rates of disease progression are the reasons why genetic testing is cost-effective.”
Methods and Findings
The team developed a model to compare the cost-effectiveness of targeted genetic testing and personalized therapy to patients with metastatic GIST who were prescribed imatinib. Data analyses were conducted from October 2019 to January 2020.
The primary outcomes of the study were quality-adjusted life-years and cost. Cost-effectiveness was defined using an incremental cost-effectiveness ratio, with an incremental cost-effectiveness ratio less than $100,000 per quality-adjusted life-year considered cost-effective.
Therapy directed by genetic testing was associated with an increase of 0.10 quality-adjusted life-years at a cost of $9,513 vs the empiric imatinib approach, leading to an incremental cost-effectiveness ratio of $92,100. Therapy directed by genetic testing remained cost-effective for testing costs up to $3,730. The researchers added that directed therapy was considered to be cost-effective 70% of the time.
“The treatment of cancer is becoming an increasingly personalized process,” said Dr. Banerjee. “There is a rapidly expanding body of research around gene-specific and even mutation-specific therapies that can be effective independent of the site of origin of a given tumor. Genetic testing provides the necessary information for patients to potentially benefit from those novel therapies.”
Disclosure: For full disclosures of the study authors, visit jamanetwork.com.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.