Genetic Testing Appears Cost Effective for Newly Diagnosed GIST

A cost-effective analysis of genetic testing and tailored first-line therapy for patients with metastatic gastrointestinal stromal tumors (GIST) suggested that using genetic testing to match treatment of KIT variations to imatinib (Gleevec) dosing is a cost-effective approach compared with empirical imatinib.¹

Researchers indicated that this economic evaluation, published in JAMA Network Open, supports the widespread adoption of standard genetic testing for newly diagnosed patients with metastatic GIST.

“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,” first author Sudeep Banerjee, MD, who did the research while in the Sicklick lab at Moores Cancer Center and who is now chief resident at David Geffen Medical School at UCLA, said in a press release.² “Avoiding ineffective treatment and reduced rates of disease progression are the reasons why genetic testing is cost-effective.”

To determine whether targeted gene testing is a cost-effective diagnostic for patients with metastatic GIST from the US payer perspective, researchers developed a Markov model to compare the cost-effectiveness of targeted gene testing and tailored first-line therapy versus empirical imatinib therapy among patients with a new diagnosis of metastatic GIST.

The primary end point was quality of life years (QALYs) and cost. Cost-effectiveness was defined using an incremental cost-effectiveness ratio, with an incremental cost-effectiveness ratio less than $100,000 per QALY considered cost-effective.

Therapy directed by targeted gene testing was found to be associated with an increase of 0.10 QALYs at a cost of $9513 compared with the empirical imatinib approach, which led to an incremental cost-effectiveness ratio of $92,100. Importantly, these findings were sensitive to the costs of targeted gene testing, drugs, and health utility model inputs.

Moreover, therapy directed by targeted gene testing continued to be cost-effective for genetic testing costs up to $3730. Overall, probabilistic sensitivity analyses demonstrated that targeted gene testing was considered cost-effective 70% of the time.

“Our results demonstrate that [targeted gene testing]-directed therapy could become progressively more cost-effective as generic imatinib continues to comprise a larger market share,” the authors explained.

Of note, clinical trial patient populations typically differ from the general patient population due to strict inclusion criteria, which may limit the generalizability of this study. However, the clinical trials analyzed in this model had permissive inclusion criteria, such as adult age, confirmed pathologic diagnosis, and only excluded patients with severe comorbidities, which the researchers suggested is a fair representation of the true patient population. Further, comparisons of clinical trials and population-based observational data demonstrate that clinical trial outcomes are generally reliable in spite of restrictive inclusion criteria.

“We recommend that all patients with a new diagnosis of metastatic GIST undergo genetic testing prior to the initiation of first-line chemotherapy,” Jason Sicklick, professor of surgery in the Division of Surgical Oncology at the University of California San Diego School of Medicine as well as surgical oncologist and co-leader of the Sarcoma Disease Team at Moores Cancer Center at UC San Diego Health, said in a press release. “In doing so, those who are unlikely to benefit from imatinib can be given a treatment better suited for their individual tumor.”

References:

1. Banerjee S, Kumar A, Lopez N, et al. Cost-effectiveness Analysis of Genetic Testing and Tailored First-Line Therapy for Patients With Metastatic Gastrointestinal Stromal Tumors. JAMA Network Open. doi: 10.1001/jamanetworkopen.2020.13565

2. Genetic Testing Cost Effective for Newly Diagnosed GIST [news release]. UC San Diego News Center. Published September 28, 2020. Accessed October 1, 2020. https://ucsdnews.ucsd.edu/pressrelease/genetic-testing-cost-effective-for-newly-diagnosed-gist