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Idelalisib: Worse Outcomes in the Clinical Setting vs Clinical Trials

Follicular lymphoma.

Idelalisib is used as monotherapy to treat relapsed follicular lymphoma (FL) and in conjunction with rituximab for relapsed chronic lymphocytic leukemia (CLL). There is a dearth of data on real-world population outcomes of this therapy. Researchers set out to discover how treatment outcomes of idelalisib for relapsed follicular lymphoma and chronic lymphocytic leukemia in the clinical setting compare with outcomes in clinical trials and found that in the clinical setting, there were less favorable results for patients treated with idelalisib.

Two clinical trials were used in this study to compare with outcomes in the clinical setting. Study 101-09 was a phase 2, single-group, open-label trial that supported accelerated approval of idelalisib for relapsed or refractory FL. The other clinical trial, 312-0116, was a phase 3, multicenter, randomized, double-blind trial that supported approval of idelalisib and rituximab for relapsed CLL. Clinical trial participants were compared with 305 Medicare beneficiaries who received idelalisib for FL and 294 Medicare beneficiaries who received idelalisib plus rituximab for CLL.

Results revealed that overall, Medicare beneficiaries were older with increased comorbidity, in addition to having a decreased median treatment duration for CLL but not for FL. Compared with trial participants, Medicare beneficiaries also had a higher mortality rate and a higher fatal infection rate per 100 person-years for both CLL and FL. Clinical trial participants underwent twice as many dose reductions as Medicare beneficiaries. A hospitalized infection within 6 months prior to receiving idelalisib was linked to a 2.11-fold higher rate for on-treatment fatal infections in the Medicare group compared to the clinical trial group.

"We observed substantial imbalances in baseline comorbidities and treatment outcomes between Medicare beneficiaries and trial participants aged 65 years or older," conclude the study authors, led by Steven T. Bird, PhD, PharmD, MS, of the Office of Pharmacovigilance and Epidemiology, Food and Drug Administration. "Immunosuppression-related toxic effects, including infections, may have somewhat reduced in trials by more frequent dose reductions and exclusion of patients with ongoing infections. Selective eligibility criteria and closer monitoring of trial patients may be responsible for limited generalizability of trial data to clinical practice."

For More Information

Bird ST, Tian F, Flowers N, et al (2019). Idelalisib for treatment of relapsed follicular lymphoma and chronic lymphocytic leukemia: a comparison of treatment outcomes in clinical trial participants vs Medicare beneficiaries. JAMA Oncol. [Epub ahead of print] DOI:10.1001/jamaoncol.2019.3994

Image Courtesy of Wikimedia Commons. Licensed under CC-BY-SA-3.0

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