{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,13]],"date-time":"2026-10-13T19:24:16Z","timestamp":1791919456093,"version":"4.3.4"},"reference-count":14,"publisher":"American Society of Clinical Oncology (ASCO)","issue":"5","content-domain":{"domain":["ascopubs.org"],"crossmark-restriction":true},"short-container-title":["JGO"],"published-print":{"date-parts":[[2019,12]]},"abstract":"<jats:sec><jats:title>PURPOSE<\/jats:title><jats:p> In PALOMA-2, palbociclib plus letrozole significantly improved progression-free survival (PFS) as initial treatment of estrogen receptor\u2013positive\/human epidermal growth factor receptor 2\u2013negative advanced breast cancer. We assessed the benefit of palbociclib plus letrozole in Asians. <\/jats:p><\/jats:sec><jats:sec><jats:title>PATIENTS AND METHODS<\/jats:title><jats:p> Of 666 enrolled postmenopausal women with estrogen receptor\u2013positive\/human epidermal growth factor receptor 2\u2013negative advanced breast cancer (no prior treatment of advanced disease), 95 were Asian. Patients were randomly assigned 2:1 to receive palbociclib plus letrozole or placebo plus letrozole. The primary end point was investigator-assessed PFS. Secondary end points were overall survival, objective response, patient-reported outcomes, pharmacokinetics, and safety. <\/jats:p><\/jats:sec><jats:sec><jats:title>RESULTS<\/jats:title><jats:p> Median PFS was significantly longer in Asian patients who received palbociclib plus letrozole versus placebo plus letrozole (25.7 months [95% CI, 19.2 months to not estimable] v 13.9 months [95% CI, 7.4 to 22.0 months]; hazard ratio, 0.48; 95% CI, 0.27 to 0.87; P = .007). The most common toxicities with palbociclib were hematologic and more frequent among Asians versus non-Asians: neutropenia (any grade, 95.4% v 76.8%; grade 3\/4, 89.2% v 62.5%), leukopenia (43.1% v 38.3%; 32.3% v 23.5%), and thrombocytopenia (27.7% v 13.5%; 4.6% v 1.1%). No Asians had febrile neutropenia. Discontinuation rates as a result of adverse events were similar among Asian and non-Asian patients who received palbociclib plus letrozole (10.8% and 9.5%). In Asians, quality of life (QOL) was maintained with no significant differences observed between treatments from baseline in breast cancer\u2013specific QOL and general health status scores. Change from baseline in EuroQol five dimensions index scores was significantly higher with palbociclib plus letrozole (0.013 v \u20130.069; P = .0132). Geometric mean palbociclib trough concentration values were higher in Asians versus non-Asians (93.8 v 61.7 ng\/mL). <\/jats:p><\/jats:sec><jats:sec><jats:title>CONCLUSION<\/jats:title><jats:p> Consistent with the overall study population, the addition of palbociclib to letrozole significantly improved PFS in Asians. Hematologic toxicities were more frequent in Asians versus non-Asians but manageable with early dose modifications while maintaining QOL. <\/jats:p><\/jats:sec>","DOI":"10.1200\/jgo.18.00173","type":"journal-article","created":{"date-parts":[[2019,5,24]],"date-time":"2019-05-24T19:58:14Z","timestamp":1558727894000},"page":"1-19","update-policy":"https:\/\/doi.org\/10.1200\/crossmark","source":"Crossref","is-referenced-by-count":27,"title":["Palbociclib Plus Letrozole as First-Line Therapy in Postmenopausal Asian Women With Metastatic Breast Cancer: Results From the Phase III, Randomized PALOMA-2 Study"],"prefix":"10.1200","author":[{"given":"Seock-Ah","family":"Im","sequence":"first","affiliation":[{"name":"Seoul National Hospital, Cancer Research Institute, Seoul National University College of Medicine, Seoul, South Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hirofumi","family":"Mukai","sequence":"additional","affiliation":[{"name":"National Cancer Center Hospital East, Chiba, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"In Hae","family":"Park","sequence":"additional","affiliation":[{"name":"National Cancer Center, Gyeonggi-do, South Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Norikazu","family":"Masuda","sequence":"additional","affiliation":[{"name":"National Hospital Organization Osaka National Hospital, Osaka, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chikako","family":"Shimizu","sequence":"additional","affiliation":[{"name":"National Center for Global Health and Medicine, Tokyo, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sung-Bae","family":"Kim","sequence":"additional","affiliation":[{"name":"University of Ulsan College of Medicine, Seoul, South Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Young-Hyuck","family":"Im","sequence":"additional","affiliation":[{"name":"Sungkyunkwan University School of Medicine, Seoul, South Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shoichiro","family":"Ohtani","sequence":"additional","affiliation":[{"name":"Hiroshima City Hospital, Hiroshima, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Cynthia","family":"Huang Bartlett","sequence":"additional","affiliation":[{"name":"Pfizer, Collegeville, PA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dongrui R.","family":"Lu","sequence":"additional","affiliation":[{"name":"Pfizer, La Jolla, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shrividya","family":"Iyer","sequence":"additional","affiliation":[{"name":"Pfizer, New York, NY"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuko","family":"Mori","sequence":"additional","affiliation":[{"name":"Pfizer Japan, Tokyo, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ave","family":"Mori","sequence":"additional","affiliation":[{"name":"Pfizer Srl, Milan, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eric","family":"Gauthier","sequence":"additional","affiliation":[{"name":"Pfizer, San Francisco, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Richard S.","family":"Finn","sequence":"additional","affiliation":[{"name":"David Geffen School of Medicine, Los Angeles, CA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Masakazu","family":"Toi","sequence":"additional","affiliation":[{"name":"Kyoto University, Kyoto, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"233","reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.3322\/caac.21262"},{"key":"B2","doi-asserted-by":"publisher","DOI":"10.1158\/1055-9965.EPI-10-0437"},{"key":"B3","doi-asserted-by":"publisher","DOI":"10.1093\/jnci\/djv107"},{"key":"B4","doi-asserted-by":"publisher","DOI":"10.1016\/S1470-2045(14)71159-3"},{"key":"B5","doi-asserted-by":"publisher","DOI":"10.1093\/annonc\/mdu385"},{"key":"B7","doi-asserted-by":"publisher","DOI":"10.1186\/bcr2419"},{"key":"B8","doi-asserted-by":"publisher","DOI":"10.1200\/JGO.2016.008318"},{"key":"B9","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa1607303"},{"key":"B10","doi-asserted-by":"publisher","DOI":"10.1634\/theoncologist.2014-0033"},{"key":"B11","doi-asserted-by":"publisher","DOI":"10.1111\/ajco.12116"},{"key":"B12","doi-asserted-by":"publisher","DOI":"10.1634\/theoncologist.2016-0097"},{"key":"B13","doi-asserted-by":"publisher","DOI":"10.1016\/j.ejca.2008.10.026"},{"key":"B15","doi-asserted-by":"crossref","first-page":"425","DOI":"10.1016\/S1470-2045(15)00613-0","volume":"17","author":"Cristofanilli 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Oncology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/ascopubs.org\/doi\/pdfdirect\/10.1200\/JGO.18.00173","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,5,29]],"date-time":"2022-05-29T10:55:12Z","timestamp":1653821712000},"score":1,"resource":{"primary":{"URL":"https:\/\/ascopubs.org\/doi\/10.1200\/JGO.18.00173"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,12]]},"references-count":14,"journal-issue":{"issue":"5","published-print":{"date-parts":[[2019,12]]}},"alternative-id":["10.1200\/JGO.18.00173"],"URL":"https:\/\/doi.org\/10.1200\/jgo.18.00173","relation":{},"ISSN":["2378-9506"],"issn-type":[{"value":"2378-9506","type":"electronic"}],"subject":[],"published":{"date-parts":[[2019,12]]},"assertion":[{"value":"2019-03-12","order":2,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication 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