{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,4]],"date-time":"2026-06-04T13:12:13Z","timestamp":1780578733452,"version":"3.54.1"},"reference-count":50,"publisher":"Oxford University Press (OUP)","issue":"6","license":[{"start":{"date-parts":[[2026,5,7]],"date-time":"2026-05-07T00:00:00Z","timestamp":1778112000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100004319","name":"Pfizer Inc","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100004319","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,5,8]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Cyclin-dependent kinase 4\/6 inhibitors (CDK4\/6is), palbociclib, ribociclib, and abemaciclib, are approved for HR+\/HER2\u2212 metastatic breast cancer (mBC). This real-world study evaluated treatment durations and subsequent treatments of patients with HR+\/HER2\u2212 mBC who received CDK4\/6is plus aromatase inhibitor (AI) in the United States.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Adult patients with HR+\/HER2\u2212 mBC who initiated first-line (1L) CDK4\/6is plus AI (February 2015-July 2024) were selected from the US-based Flatiron Health Research database. Stabilized inverse probability of treatment weighting (sIPTW) was conducted. Kaplan\u2212Meier analyses estimated treatment durations.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Of 11\u2009557 patients, 8109, 2006, and 1442 received 1L palbociclib, ribociclib, and abemaciclib, respectively. After sIPTW, treatment duration was longer for the palbociclib group (median: 20.7\u2009months) than the ribociclib (18.3\u2009months) and abemaciclib (17.1\u2009months) groups (ribociclib vs palbociclib: hazard ratio [HR] = 1.12 [95% confidence interval (CI), 1.05-1.20], P\u2009=\u2009.0008; abemaciclib vs palbociclib: HR\u2009=\u20091.13 [95% CI, 1.05-1.22], P\u2009=\u2009.0012). Treatment durations were similar between the ribociclib and abemaciclib groups (HR\u2009=\u20091.01 [95% CI, 0.92-1.11], P\u2009=\u2009.8280). Twelve-month treatment discontinuation rates were higher among patients initiating ribociclib or abemaciclib, at 39.4% and 41.1%, respectively, than among patients initiating palbociclib (33.3%). In the analysis of patients who initiated palbociclib, ribociclib, or abemaciclib from 2017 onward, 49.9%, 37.3%, and 39.4%, respectively, received subsequent treatments; CDK4\/6i-containing regimens accounted for 42.3%, 54.1%, and 55.7%, respectively; notably, more patients initially treated with ribociclib or abemaciclib transitioned to palbociclib than those who switched oppositely.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Treatment durations, discontinuation rates, and subsequent treatments differ between CDK4\/6is for HR+\/HER2\u2212 mBC in US routine clinical practice.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Clinical Trial Registration Number<\/jats:title>\n                    <jats:p>NCT06495164<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1093\/oncolo\/oyag182","type":"journal-article","created":{"date-parts":[[2026,5,6]],"date-time":"2026-05-06T11:41:40Z","timestamp":1778067700000},"source":"Crossref","is-referenced-by-count":0,"title":["Real-world treatment durations, subsequent treatments, and switching of CDK4\/6 inhibitors among patients with HR+\/HER2\u2212 metastatic breast cancer"],"prefix":"10.1093","volume":"31","author":[{"ORCID":"https:\/\/orcid.org\/0009-0006-2725-3579","authenticated-orcid":false,"given":"Adam","family":"Brufsky","sequence":"first","affiliation":[{"name":"Division of Hematology\/Oncology, Department of Medicine, UPMC Hillman Cancer Center, University of Pittsburgh Medical Center , Pittsburgh, PA 15213,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rachel M","family":"Layman","sequence":"additional","affiliation":[{"name":"Department of Breast Medical Oncology, The University of Texas MD Anderson Cancer Center , Houston, TX 77030,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xianchen","family":"Liu","sequence":"additional","affiliation":[{"name":"US Oncology Medical Affairs, Pfizer Inc. , New York, NY 10001,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Benjamin","family":"Li","sequence":"additional","affiliation":[{"name":"Global Biometrics & Data Management, Pfizer Inc. , New York, NY 10001,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lynn","family":"McRoy","sequence":"additional","affiliation":[{"name":"US Oncology Medical Affairs, Pfizer Inc. , New York, NY 10001,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aaron","family":"Cohen","sequence":"additional","affiliation":[{"name":"Research Oncology, Flatiron Health Inc. , New York, NY 10013,","place":["United 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