{
  "abstract": "Background and Importance Breast cancer (BC) is the most common malignant tumour in women worldwide and in Spain, with an estimated 286,664 cases in 2024. Despite therapeutic advances, early-stage high risk HR+/HER2− BC patients still face a 40% risk of developing incurable metastatic disease over 20 years. CDK4/6 inhibitors combined with endocrine therapy have doubled progression-free survival. Approved agents include abemaciclib, palbociclib, and ribociclib. In the MONARCH 2 trial, abemaciclib increased overall survival by 9.4 months and reduced progression or death risk by 44.7%, with no significant impact on quality of life. Main adverse events include neutropenia, diarrhoea, elevated aminotransferases, and venous thromboembolism.Aim and Objectives To evaluate the effectiveness and safety of abemaciclib in women diagnosed with metastatic breast cancer, hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2−), treated at the Regional University Hospital of Málaga.Material and Methods An observational, retrospective, single-centre study was conducted at the Regional University Hospital of Málaga (Hospital Pharmacy Service) from January 2021 to December 2024. Inclusion criteria: women aged 18–60 years, any race, with HR+/HER2− metastatic BC. Exclusion criteria: age <18, other BC subtypes, additional malignancies, or marker-modifying treatments. Variables included epidemiological and clinical data, disease stage (I–IV), HER2, HR, Ca 15.3 (>30 uU/ml), Ki67, and metastatic involvement. Treatment was abemaciclib 150 mg/12h, alone or combined with anastrozole, letrozole, or fulvestrant. Efficacy outcomes: overall survival (OS), progression-free survival (PFS), objective response rate (ORR), and duration of response (DoR). Safety outcomes: adverse event incidence, dose reductions, and treatment delays.Results Among 77 patients treated with abemaciclib, 13 (17%) had metastatic BC. Mean age was 52 years, all ER-positive/HER2−. Seventy-seven percent received abemaciclib as first-line therapy, most frequently with fulvestrant. At data cut-off, median OS was not reached; PFS lower limit was 16 months, ORR 84.6%, and mean DoR 382 days. Adverse events occurred in 85%, mainly neutropenia (46%) and diarrhoea (38%), leading to dose reductions (50%) and treatment delays (38%).Conclusion and Relevance Abemaciclib, in combination with hormone therapy, is an effective and well tolerated treatment for HR+/HER2− metastatic BC. Larger multicentre studies are needed to confirm these findings and strengthen the evidence base.Conflict of Interest No conflict of interest",
  "authors": [
    {
      "affiliations": [
        "Hospital Regional Universitario De Málaga, Farmacia Hospitalaria, Málaga, Spain"
      ],
      "name": "Á Ballesteros Fernández"
    },
    {
      "affiliations": [
        "Hospital Regional De Málaga, Farmacia Hospitalaria, Malaga, Spain"
      ],
      "name": "C Lara Ramos"
    },
    {
      "affiliations": [
        "Hospital Regional De Málaga, Farmacia Hospitalaria, Malaga, Spain"
      ],
      "name": "R Diaz Perales"
    },
    {
      "affiliations": [
        "Hospital Regional De Málaga, Farmacia Hospitalaria, Málaga, Spain"
      ],
      "name": "JC Del Rio Valencia"
    },
    {
      "affiliations": [
        "Hospital Regional De Málaga, Farmacia Hospitalaria, Málaga, Spain"
      ],
      "name": "A Jurado Romero"
    },
    {
      "affiliations": [
        "Hospital Regional De Málaga, Farmacia Hospitalaria, Málaga, Spain"
      ],
      "name": "S Martin Clavo"
    },
    {
      "affiliations": [
        "Hospital Regional De Málaga, Farmacia Hospitalaria, Málaga, Spain"
      ],
      "name": "M Rouco Blanco-Rajoy"
    },
    {
      "affiliations": [
        "Hospital Regional De Málaga, Farmacia Hospitalaria, Málaga, Spain"
      ],
      "name": "C Gallego Fernández"
    }
  ],
  "title": "4CPS-174 Effectiveness and safety of abemaciclib in women with hormone receptor-positive, her-2-negative metastatic breast cancer: results in routine clinical practice",
  "uid": "7cd827c9-fe04-5ff8-bfef-ebdb93b7e6dd"
}