{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,16]],"date-time":"2026-04-16T16:24:54Z","timestamp":1776356694065,"version":"3.51.2"},"reference-count":26,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2026,4,16]],"date-time":"2026-04-16T00:00:00Z","timestamp":1776297600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Cancers"],"abstract":"<jats:p>Background: Hormone receptor-positive (HR+), Human Epidermal growth factor Receptor 2 (HER2-negative) metastatic breast cancer (MBC) represents a substantial proportion of breast cancer cases in Saudi Arabia. Despite the established efficacy of cyclin-dependent kinase 4 and 6 (CDK4\/6) inhibitors, particularly Palbociclib, in randomized control trials, real-world data from local institutions in Saudi Arabia remain limited. Objectives: This study aimed to evaluate progression-free survival (PFS), overall survival (OS), and toxicity profile among HR+, HER2-negative MBC female patients treated with Palbociclib at King Fahad Medical City (KFMC). Methods: A retrospective study was conducted on female patients with HR+\/HER2-negative MBC treated with oral palbociclib combined with endocrine therapy (ET) at KFMC between January 2021 and September 2024. Data were collected from electronic health records. Descriptive statistics were conducted using mean for continuous variables and frequency for categorical variables. Survival analyses were conducted using Cox regression, log-rank tests and Kaplan\u2013Meier analysis. Results: A total of 169 female patients with HR+\/HER2\u2212 MBC were included. In the first-line setting, the median PFS was 20.14 months (95% CI: 14.65\u201330.49), compared with 11.3 months (95% CI: 7.98\u2013not estimable) in the second-line setting. For OS, the median OS values were 53.1 months (95% CI: 41.2\u2013not estimable) in the first-line group and 23.7 months (95% CI: 18.5\u2013not estimable) in the second-line group. Significant predictors of shorter PFS included age, Body Mass Index (BMI), type of ET, cancer type, line of therapy, family history of cancer, and history of VTE. Visceral metastasis (HR = 3.087; p = 0.0229) and ECOG performance status of 4 (HR = 13.86; p = 0.0156) were associated with significantly shorter OS. The most common hematological adverse events (AEs) were neutropenia (45.6%), followed by anemia (5.9%), leukopenia (5.3%), and back pain (5.3%). Most toxicities were managed with dose reduction, holding treatment, or supportive care. Conclusions: Palbociclib demonstrated favorable survival outcomes and a manageable safety profile, with neutropenia being the most common AE. This study provides region-specific real-world evidence supporting the use of Palbociclib in HR+\/HER2\u2212 MBC. These findings align with global trial data and highlight the importance of individualized treatment in clinical practice.<\/jats:p>","DOI":"10.3390\/cancers18081270","type":"journal-article","created":{"date-parts":[[2026,4,16]],"date-time":"2026-04-16T15:14:12Z","timestamp":1776352452000},"page":"1270","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Real-World Outcomes of Palbociclib with Endocrine Therapy in HR+\/HER2\u2212 Metastatic Breast Cancer: A Retrospective Study from Saudi Arabia"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0754-7493","authenticated-orcid":false,"given":"Abdalrhman H.","family":"Alanizi","sequence":"first","affiliation":[{"name":"Pharmaceutical Care Services, King Abdullah bin Abdulaziz University Hospital, Riyadh 11671, Saudi Arabia"},{"name":"Department of Pharmacy Practice, College of Pharmacy, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-7559-9082","authenticated-orcid":false,"given":"Sarah N.","family":"Al-Shaiban","sequence":"additional","affiliation":[{"name":"Department of Pharmacy, Al Kharj Military Industries Corporation Hospital, Al-Kharj 16417, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0005-2324-1565","authenticated-orcid":false,"given":"Reema","family":"Alotaibi","sequence":"additional","affiliation":[{"name":"Pharmaceutical Care Services, King Abdullah bin Abdulaziz University Hospital, Riyadh 11671, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Reem","family":"Qubaiban","sequence":"additional","affiliation":[{"name":"National Cancer Center, Riyadh 13315, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Esra\u2019a","family":"Khader","sequence":"additional","affiliation":[{"name":"College of Pharmacy, Department of Pharmacy Practice and Science, University of Iowa, Iowa City, IA 52242, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ahmed S.","family":"Alanazi","sequence":"additional","affiliation":[{"name":"Clinical Pharmacy, Pharmacy Service Administration, King Fahad Medical City, Riyadh 11525, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hatoon","family":"Bakhribah","sequence":"additional","affiliation":[{"name":"Comprehensive Cancer Center, King Fahad Medical City, Riyadh 11525, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nawal","family":"Alsubaie","sequence":"additional","affiliation":[{"name":"Department of Pharmacy Practice, College of Pharmacy, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-5358-0305","authenticated-orcid":false,"given":"Amani S.","family":"Alrossies","sequence":"additional","affiliation":[{"name":"Department of Pharmacy Practice, College of Pharmacy, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sireen Abdul Rahim","family":"Shilbayeh","sequence":"additional","affiliation":[{"name":"Department of Pharmacy Practice, College of Pharmacy, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-7174-3839","authenticated-orcid":false,"given":"Ammena Y.","family":"Binsaleh","sequence":"additional","affiliation":[{"name":"Department of Pharmacy Practice, College of Pharmacy, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,4,16]]},"reference":[{"key":"ref_1","unstructured":"World Health Organization (2024, April 05). Cancer Today. International Agency for Research on Cancer. Available online: https:\/\/gco.iarc.who.int\/today."},{"key":"ref_2","first-page":"438","article-title":"Breast cancer statistics, 2019","volume":"69","author":"DeSantis","year":"2019","journal-title":"CA Cancer J. 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