{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T12:07:44Z","timestamp":1788955664997,"version":"build-2803163510"},"reference-count":30,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,9,7]],"date-time":"2026-09-07T00:00:00Z","timestamp":1788739200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Oncol."],"abstract":"<jats:sec>\n                    <jats:title>Objective<\/jats:title>\n                    <jats:p>This study aimed to characterize the tumor response rate, progression-free survival (PFS), and overall survival (OS) among patients with HR-positive, HER2-negative metastatic breast cancer receiving CDK4\/6 inhibitors plus endocrine therapy at Ho Chi Minh City Oncology Hospital. Secondary objectives included identifying clinical factors associated with survival outcomes and characterizing treatment-related toxicities.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Materials and methods<\/jats:title>\n                    <jats:p>We conducted a retrospective cohort study enrolling 107 patients who received first-line ribociclib or palbociclib in combination with an aromatase inhibitor or fulvestrant at Ho Chi Minh City Oncology Hospital between March 1, 2021, and April 1, 2023.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>The median follow-up duration was 29 months. The median PFS was 28.0 months. The Kaplan\u2013Meier-estimated PFS rates at 12 and 24 months were 66.4% (95% CI, 56.6%\u201374.4%) and 54.1% (95% CI, 44.2%\u201363.0%), respectively. The median OS was not reached; corresponding OS rates at 12 and 24 months were 88.8% and 87.8%, respectively. On multivariate Cox regression analysis, ER and PR expression levels emerged as independent prognostic determinants of PFS. Grade 3\u20134 neutropenia was observed in 58.8% of patients; all events were managed through dose interruption or reduction, and no cases of febrile neutropenia were documented.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>CDK4\/6 inhibitors (ribociclib or palbociclib) combined with endocrine therapy demonstrated favorable efficacy and tolerability in Vietnamese patients with HR-positive, HER2-negative metastatic breast cancer. Treatment outcomes and safety profiles were consistent with those reported in pivotal clinical trials and real-world studies. These findings should be interpreted in light of the retrospective single-center design, modest sample size, non-randomized treatment allocation, and immature OS data.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fonc.2026.1871703","type":"journal-article","created":{"date-parts":[[2026,9,7]],"date-time":"2026-09-07T04:22:52Z","timestamp":1788754972000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["First-line CDK4\/6 inhibitor treatment of HR-positive, HER2-negative metastatic breast cancer: real-world data from Ho Chi Minh City Oncology Hospital, Vietnam"],"prefix":"10.3389","volume":"16","author":[{"given":"Thi Hong Duc","family":"Phan","sequence":"first","affiliation":[{"name":"Department of Oncology, Pham Ngoc Thach University of Medicine","place":["Ho Chi Minh City, Vietnam"]},{"name":"Department of General Internal Medicine, Ho Chi Minh City Oncology Hospital","place":["Ho Chi Minh City, Vietnam"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hoang Quy","family":"Nguyen","sequence":"additional","affiliation":[{"name":"Department of Oncology, School of Medicine, University of Medicine and Pharmacy at Ho Chi Minh City","place":["Ho Chi Minh City, Vietnam"]},{"name":"Department of General Internal Medicine, Ho Chi Minh City Oncology Hospital","place":["Ho Chi Minh City, Vietnam"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,9,7]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.3322\/caac.21834","article-title":"Global cancer statistics 2022: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries","volume":"74","author":"Bray","year":"2024","journal-title":"CA Cancer J Clin"},{"key":"B2","doi-asserted-by":"publisher","first-page":"66","DOI":"10.1038\/s41572-019-0111-2","article-title":"Breast cancer","volume":"5","author":"Harbeck","year":"2019","journal-title":"Nat Rev Dis Primers"},{"key":"B3","doi-asserted-by":"publisher","first-page":"427","DOI":"10.1016\/j.ccell.2018.08.008","article-title":"The genomic landscape of endocrine-resistant advanced breast cancers","volume":"34","author":"Razavi","year":"2018","journal-title":"Cancer Cell"},{"key":"B4","doi-asserted-by":"publisher","DOI":"10.1038\/s41416-020-0979-3","article-title":"Survival in patients with HR+\/HER2- metastatic breast cancer treated with initial endocrine therapy versus initial chemotherapy. A French population-based study","volume":"123","author":"Simon","year":"2020"},{"key":"B5","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa1607303","article-title":"Palbociclib and letrozole in advanced breast cancer","volume":"375","author":"Finn","year":"2016","journal-title":"N Engl J Med"},{"key":"B6","doi-asserted-by":"publisher","DOI":"10.1093\/annonc\/mdy155","article-title":"Updated results from MONALEESA-2, a phase III trial of first-line ribociclib plus letrozole versus placebo plus letrozole in hormone receptor-positive, HER2-negative advanced breast cancer","volume":"29","author":"Hortobagyi","year":"2018","journal-title":"Ann Oncol"},{"key":"B7","doi-asserted-by":"publisher","DOI":"10.1038\/s41523-018-0097-z","article-title":"MONARCH 3 final PFS: a randomized study of abemaciclib as initial therapy for advanced breast cancer","volume":"5","author":"Johnston","year":"2019","journal-title":"NPJ Breast Cancer"},{"key":"B8","doi-asserted-by":"publisher","first-page":"PO5","DOI":"10.1158\/1538-7445.SABCS23-PO5-05-07","article-title":"Abstract PO5-05-07: Efficacy and safety of first line CDK4\/6 inhibitor plus endocrine therapy for patients with HR+\/HER2- metastatic breast cancer:initial real-world experience at Ho Chi Minh city oncology hospital, Viet Nam","volume":"84","author":"Quy","year":"2024","journal-title":"Cancer Res"},{"key":"B9","doi-asserted-by":"publisher","DOI":"10.38103\/jcmhch.88.1","article-title":"Efficacy of endocrine therapy combined with CDK4\/6 inhibitors in patients with hormone receptor-positive, HER2-negative recurrent or metastatic breast cancer","volume":"88","author":"Le","year":"2023","journal-title":"J Clin Medicine Hue Cent Hosp"},{"key":"B10","doi-asserted-by":"publisher","DOI":"10.1007\/s10549-021-06334-0","article-title":"Full population results from the core phase of CompLEEment-1, a phase 3b study of ribociclib plus letrozole as first-line therapy for advanced breast cancer in an expanded population","volume":"189","author":"De Laurentiis","year":"2021","journal-title":"Breast Cancer Res Treat"},{"key":"B11","doi-asserted-by":"publisher","DOI":"10.1177\/17588359221139678","article-title":"Real-world outcomes from use of CDK4\/6 inhibitors in the management of advanced\/metastatic breast cancer in Asia","volume":"14","author":"Low","year":"2022","journal-title":"Ther Adv Med Oncol"},{"key":"B12","doi-asserted-by":"publisher","DOI":"10.1016\/j.breast.2020.11.008","article-title":"Real life efficacy of palbociclib and endocrine therapy in HR positive, HER2 negative advanced breast cancer","volume":"54","author":"Porte","year":"2020","journal-title":"Breast"},{"key":"B13","doi-asserted-by":"publisher","first-page":"994","DOI":"10.1200\/JCO.23.00137","article-title":"OS with palbociclib plus letrozole in advanced breast cancer","volume":"42","author":"Slamon","year":"2024","journal-title":"J Clin Oncol"},{"key":"B14","doi-asserted-by":"publisher","DOI":"10.1136\/esmoopen-2020-000774","article-title":"Real-world clinical outcome and toxicity data and economic aspects in patients with advanced breast cancer treated with cyclin-dependent kinase 4\/6 (CDK4\/6) inhibitors combined with endocrine therapy: the experience of the Hellenic Cooperative Oncology Group","volume":"5","author":"Fountzilas","year":"2020","journal-title":"ESMO Open"},{"key":"B15","doi-asserted-by":"publisher","first-page":"1056","DOI":"10.1200\/JCO.2022.40.16_suppl.1056","article-title":"CDK4\/6 inhibitors outcomes in patients with advanced breast cancer based on HER2-low expression","volume":"40","author":"Lapuchesky","year":"2022","journal-title":"J Clin Oncol"},{"key":"B16","doi-asserted-by":"publisher","first-page":"27","DOI":"10.1038\/s41523-023-00534-1","article-title":"Prognostic significance of HER2-low status in HR-positive\/HER2-negative advanced breast cancer treated with CDK4\/6 inhibitors","volume":"9","author":"Zattarin","year":"2023","journal-title":"NPJ Breast Cancer"},{"key":"B17","doi-asserted-by":"publisher","DOI":"10.1158\/1557-3265.SABCS24-PS2-03","article-title":"Abstract PS2-03: Comparative OS of CDK4\/6 inhibitors plus an aromatase inhibitor (AI) in HR+\/HER2- MBC in the US real-world setting","volume":"31","author":"Rugo","year":"2025","journal-title":"Clin Cancer Res"},{"key":"B18","doi-asserted-by":"publisher","DOI":"10.4143\/crt.2020.451","article-title":"Real-world clinical data of palbociclib in Asian metastatic breast cancer patients: experiences from eight institutions","volume":"53","author":"Lee","year":"2021","journal-title":"Cancer Res Treat"},{"key":"B19","doi-asserted-by":"publisher","DOI":"10.1093\/oncolo\/oyac089","article-title":"Real-world experience with CDK4\/6 inhibitors for metastatic HR+\/HER2- breast cancer at a single cancer center","volume":"27","author":"Knudsen","year":"2022","journal-title":"Oncologist"},{"key":"B20","doi-asserted-by":"publisher","DOI":"10.1177\/1758835920987651","article-title":"Patterns of treatment and outcome of palbociclib plus endocrine therapy in hormone receptor-positive\/HER2 receptor-negative metastatic breast cancer: a real-world multicentre Italian study","volume":"13","author":"Palumbo","year":"2021","journal-title":"Ther Adv Med Oncol"},{"key":"B21","doi-asserted-by":"publisher","DOI":"10.1177\/1758835918786451","article-title":"CDK4\/6 inhibition in breast cancer: current practice and future directions","volume":"10","author":"Pernas","year":"2018","journal-title":"Ther Adv Med Oncol"},{"key":"B22","doi-asserted-by":"publisher","first-page":"1063","DOI":"10.1200\/JCO.2023.41.16_suppl.1063","article-title":"Outcomes with first-line (1L) ribociclib (RIB) + endocrine therapy (ET) vs physician\u2019s choice combination chemotherapy (combo CT) by age in pre\/perimenopausal patients (pts) with aggressive HR+\/HER2- advanced breast cancer (ABC): a subgroup analysis of the RIGHT Choice trial","volume":"41","author":"El Saghir","year":"2023","journal-title":"J Clin Oncol"},{"key":"B23","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa1609709","article-title":"Ribociclib as first-line therapy for HR-positive, advanced breast cancer","volume":"375","author":"Hortobagyi","year":"2016","journal-title":"N Engl J Med"},{"key":"B24","doi-asserted-by":"publisher","DOI":"10.1055\/a-2074-0125","article-title":"Update breast cancer 2023 part 2 - advanced-stage breast cancer","volume":"83","author":"Lux","year":"2023","journal-title":"Geburtshilfe Frauenheilkd"},{"key":"B25","doi-asserted-by":"publisher","DOI":"10.1016\/j.esmorw.2024.100064","article-title":"UK multicentre real-world data of the use of cyclin-dependent kinase 4\/6 inhibitors in metastatic breast cancer","volume":"5","author":"Gullick","year":"2024","journal-title":"ESMO Real World Data Digital Oncol"},{"key":"B26","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa2114663","article-title":"OS with ribociclib plus letrozole in advanced breast cancer","volume":"386","author":"Hortobagyi","year":"2022","journal-title":"N Engl J Med"},{"key":"B27","doi-asserted-by":"publisher","first-page":"362","DOI":"10.21037\/atm-22-1002","article-title":"Efficacy and safety of palbociclib plus endocrine therapy for patients with HR+\/HER2- advanced breast cancer in real-world clinical practice","volume":"10","author":"Zhong","year":"2022","journal-title":"Ann Transl Med"},{"key":"B28","doi-asserted-by":"publisher","first-page":"37","DOI":"10.1186\/s13058-021-01409-8","article-title":"Comparative effectiveness of first-line palbociclib plus letrozole versus letrozole alone for HR+\/HER2- metastatic breast cancer in US real-world clinical practice","volume":"23","author":"DeMichele","year":"2021","journal-title":"Breast Cancer Res"},{"key":"B29","doi-asserted-by":"publisher","first-page":"JGO. 18.00239","DOI":"10.1200\/jgo.18.00239","article-title":"Real-world treatment patterns and clinical outcomes in patients receiving palbociclib for hormone receptor\u2013positive, human epidermal growth factor receptor 2\u2013negative advanced or metastatic breast cancer in Argentina: the IRIS study","volume":"5","author":"Waller","year":"2019","journal-title":"J Global Oncol"},{"key":"B30","doi-asserted-by":"publisher","first-page":"114","DOI":"10.1038\/s41523-022-00479-x","article-title":"Real-world study of OS with palbociclib plus aromatase inhibitor in HR+\/HER2- metastatic breast cancer","volume":"8","author":"Rugo","year":"2022","journal-title":"NPJ Breast Cancer"}],"container-title":["Frontiers in Oncology"],"original-title":[],"link":[{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fonc.2026.1871703\/full","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T11:32:37Z","timestamp":1788953557000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fonc.2026.1871703\/full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,7]]},"references-count":30,"alternative-id":["10.3389\/fonc.2026.1871703"],"URL":"https:\/\/doi.org\/10.3389\/fonc.2026.1871703","relation":{},"ISSN":["2234-943X"],"issn-type":[{"value":"2234-943X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,7]]},"article-number":"1871703"}}