Garth W Strohbehn1,2,3,4,5, Robert Holleman1, Jennifer Burns1, Mandi L Klamerus1, Michael J Kelley6,7,8, Eve A Kerr1,4, Nithya Ramnath2,3,4,5, Timothy P Hofer1,4. 1. Veterans Affairs Center for Clinical Management Research, Ann Arbor, Michigan. 2. Rogel Cancer Center, University of Michigan, Ann Arbor. 3. Division of Oncology, LTC Charles S Kettles VA Medical Center, Ann Arbor. 4. Department of Internal Medicine, University of Michigan, Ann Arbor. 5. Veterans Affairs Lung Precision Oncology Program, Ann Arbor, Michigan. 6. Durham Veterans Affairs Health Care System, Durham, North Carolina. 7. Department of Medicine, Duke University Medical Center, Durham, North Carolina. 8. Department of Veterans Affairs, National Oncology Program Office, Office of Specialty Care, Durham, North Carolina.
Abstract
Importance: Extended-interval dosing of pembrolizumab (400 mg every 6 weeks) was approved by US Food and Drug Administration (FDA) in April 2020 as an alternative to standard-interval dosing (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. Neither adoption nor effectiveness of extended interval in the US has been adequately described. Objective: To describe adoption of extended-interval dosing of pembrolizumab since its FDA approval and to measure its preliminary real-world effectiveness compared with standard-interval dosing. Design, Setting, and Participants: This was a retrospective cohort study that used data from the Veterans Health Administration (VHA), a US-based, nationwide single-payer health system. Participants were veterans who were prescribed single-agent pembrolizumab within the VHA between April 1, 2020, and July 1, 2021. Patients receiving combinations of pembrolizumab and cytotoxic chemotherapy or tyrosine kinase inhibitors were excluded. A subcohort of veterans with non-small cell lung cancer (NSCLC) was also identified using claims-based codes. Exposures: Single-agent pembrolizumab at extended or standard intervals. Main Outcomes and Measures: The number and proportion of single-agent pembrolizumab prescriptions that were extended compared with standard interval. Effectiveness was described in terms of time-to-treatment discontinuation (TTD) and extended- to standard-interval pembrolizumab prescriptions were compared using Cox proportional hazards regression. Results: A total of 835 veterans (mean age [SD], 70.9 [8.7] years; 809 [96.9%] men) began single-agent pembrolizumab during the study period (all-diseases cohort), and of these, 234 (mean [SD] age, 71.6 [7.3] years; 225 [96.2%] men) had NSCLC (NSCLC cohort). 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). Conclusions and Relevance: This retrospective cohort study found that extended-interval dosing comprised a minority of single-agent pembrolizumab prescriptions despite the FDA approval and its potential health system and public health 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. This study provides further support for extended-interval pembrolizumab dosing.
Importance: Extended-interval dosing of pembrolizumab (400 mg every 6 weeks) was approved by US Food and Drug Administration (FDA) in April 2020 as an alternative to standard-interval dosing (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. Neither adoption nor effectiveness of extended interval in the US has been adequately described. Objective: To describe adoption of extended-interval dosing of pembrolizumab since its FDA approval and to measure its preliminary real-world effectiveness compared with standard-interval dosing. Design, Setting, and Participants: This was a retrospective cohort study that used data from the Veterans Health Administration (VHA), a US-based, nationwide single-payer health system. Participants were veterans who were prescribed single-agent pembrolizumab within the VHA between April 1, 2020, and July 1, 2021. Patients receiving combinations of pembrolizumab and cytotoxic chemotherapy or tyrosine kinase inhibitors were excluded. A subcohort of veterans with non-small cell lung cancer (NSCLC) was also identified using claims-based codes. Exposures: Single-agent pembrolizumab at extended or standard intervals. Main Outcomes and Measures: The number and proportion of single-agent pembrolizumab prescriptions that were extended compared with standard interval. Effectiveness was described in terms of time-to-treatment discontinuation (TTD) and extended- to standard-interval pembrolizumab prescriptions were compared using Cox proportional hazards regression. Results: A total of 835 veterans (mean age [SD], 70.9 [8.7] years; 809 [96.9%] men) began single-agent pembrolizumab during the study period (all-diseases cohort), and of these, 234 (mean [SD] age, 71.6 [7.3] years; 225 [96.2%] men) had NSCLC (NSCLC cohort). 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). Conclusions and Relevance: This retrospective cohort study found that extended-interval dosing comprised a minority of single-agent pembrolizumab prescriptions despite the FDA approval and its potential health system and public health 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. This study provides further support for extended-interval pembrolizumab dosing.
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