ANN ARBOR, MI — Even though extended-interval dosing of single-agent pembrolizumab isn’t often used, despite approval from the U.S. Food and Drug Administration, the practice has potential health system and public health benefits, according to a VA study.
The FDA approved extended-interval dosing of pembrolizumab (400 mg every 6 weeks) in April 2020 as an alternative to standard-interval dosing of 200 mg every 3 weeks. “Extended-interval dosing may enhance access, alleviate patient and health system financial toxicity and improve patient quality of life, particularly during the COVID-19 pandemic,” according to a report in JAMA Oncology, which added that the effects have not been adequately described.
To remedy that, researchers from the Ann Arbor, MI, VAMC, the University of Michigan and colleagues conducted a retrospective cohort study that used data from the VHA. Included were veterans who were prescribed single-agent pembrolizumab within the VHA between April 1, 2020, and July 1, 2021. A subcohort of veterans with non-small cell lung cancer (NSCLC) was also identified using claims-based codes.
The study excluded patients receiving combinations of pembrolizumab and cytotoxic chemotherapy or tyrosine kinase inhibitors.
The study team was focused on the number and proportion of single-agent pembrolizumab prescriptions that were extended compared with standard interval. The researchers described effectiveness in terms of time-to-treatment discontinuation (TTD) and extended- to standard-interval pembrolizumab prescriptions.
Of the 835 veterans (mean age [SD], 70.9 [8.7] years; 809 [96.9%] men) who began single-agent pembrolizumab during the study period (all-diseases cohort), 234 has NSCL. Those patients had a mean age of 71.6 and were 96.2% male.
Study results indicated that “extended-interval adoption” reached its steady-state plateau of approximately 35% by January 2021; 65% of participants who began standard-interval single-agent pembrolizumab received only standard-interval dosing during the treatment course. In analysis consistent with the intention-to-treat principle, no differences in TTD were observed between standard- and extended-interval dosing in either the all-diseases cohort (HR, 1.00; 95% CI, 1.00-1.00) or the NSCLC cohort (HR, 1.00; 95% CI, 1.00-1.00).
The authors pointed out that extended-interval dosing made up a minority of single-agent pembrolizumab prescriptions, despite the FDA approval and potential benefits. “The findings support the TTD equivalence of standard- and extended-interval pembrolizumab across indications, complementing clinical pharmacology and single-arm clinical trial data in melanoma,” they wrote. “This study provides further support for extended-interval pembrolizumab dosing.”
- Strohbehn GW, Holleman R, Burns J, Klamerus ML, et. al. Adoption of Extended-Interval Dosing of Single-Agent Pembrolizumab and Comparative Effectiveness vs Standard Dosing in Time-to-Treatment Discontinuation. JAMA Oncol. 2022 Nov 1;8(11):1663-1667. doi: 10.1001/jamaoncol.2022.4109. PMID: 36136314; PMCID: PMC9501784.