Doctors treating patients with bladder cancer prescribed immunotherapies less often, and chemotherapy more, following the Food and Drug Administration’s decision to restrict the approvals of Keytruda and Tecentriq in the tumor type, new research published Tuesday in JAMA found. The two cancer immunotherapies were approved in 2017 for certain previously untreated bladder cancer patients, based on data from single-arm Phase 2 trials. Results from Phase 3 follow-up studies, however, showed patients receiving platinum-based chemotherapy were living longer than those given immunotherapy. Those findings led the FDA in June 2018 to limit the labeling for both drugs to only patients who test positive for PD-L1, a biomarker shown in some cases to be correlated with response to immunotherapy. Researchers from Flatiron Health, the FDA, the University of Pennsylvania and the Icahn School of Medicine were able to link that label modification with changes in practice.
Quick approvals for both Roche’s Tecentriq (atezolizumab) and Merck & Co.’s Keytruda (pembrolizumab) in the tumor type were later narrowed when fuller evidence became available suggesting worse survival rates — a relatively rare regulatory revision.
The new JAMA research suggests physicians are responsive to such changes.
“Given the rapid growth of oncology therapies receiving accelerated approval, how regulatory response to postmarket safety events affect use of such drugs is important,” the researchers wrote.
“This study suggests that the FDA label changes were associated with changes in practice, even when the decision was based on emerging trial data.”
The study authors used a database of deidentified electronic health records kept by Flatiron Health, now owned by Roche. Utilization rates for cancer immunotherapy, chemotherapy and PD-L1 testing were tracked across 1,965 patients, and assessed for changes following the FDA’s June 2018 label restriction.
Prescribing of immunotherapy, which had been rising, decreased following that decision, the research showed. Chemotherapy and PD-L1 testing use, on the other hand, increased. All changes met the threshold for statistical significance.
The findings put a brighter spotlight on forthcoming data from a Phase 3 Roche study of Tecentriq in previously untreated bladder cancer. Results, expected Monday at the European Society of Medical Oncology’s annual meeting, will give doctors a better sense of how immunotherapy could help patients whose tumors test positive for PD-L1.
The trial, along with a Merck study, was the source of the FDA’s initial warning, which spurred Roche and Merck to stop enrolling low PD-L1 expressing patients to monotherapy treatment.
Results showing a strong benefit could reverse the declining use of immunotherapy in first-line bladder cancer that researchers observed.