Response of Palbociclib in Old Age Metastatic Breast Cancer Patient

Background and Aims: Metastatic breast cancer (MBC) poses significant treatment challenges especially in elderly patients due to physiological changes associated with age, reduced tolerability of treatment, and comorbidities. Palbociclib, a cyclin-dependent kinase 4/6 inhibitor, has shown clinical efficacy in HR+/HER2- MBC; however, its tolerability and dose adjustment requirements in older populations remain inadequately explored. This study aimed to evaluate the response and tolerability of Palbociclib among elderly female MBC patients aged 65-80 years. Patients and Methods: This prospective observational study investigated 60 MBC cases at the Department of Medical Oncology, Hameed Latif Hospital, Lahore, from December 2024 to June 2025. Eligible female patients aged 65-80 years with HR+/HER2- MBC and ECOG performance status 0–2 were included using non-probability consecutive sampling. Oral Palbociclib 125 mg daily dosage for 21 days on and 7 days off prescribed to each patient. Demographic data, number of metastases, metastatic sites, and baseline ECOG status recorded. Three months follow-up done for treatment response (dose modification and withdrawals) and adverse effects. A 125 mg dose reduced to 100 mg, then 75 mg if required. Drug withdrawal occurred upon persistent or intolerable adverse events. Adverse events such as anemia, febrile neutropenia, Thrombocytopenia, Diarrhea, Elevated LFTs, Renal Function Impairment, Fatigue, Vomiting, and QTc Prolongation recorded. Results: The overall median age was 72 years (IQR 65-80 years). The prevalence of newly diagnosed and recurrent or progressive disease was 16 (26.7%) and 44 (73.3%), respectively. The Starting dose of palbociclib 125 mg (standard), 100 mg, and 75 mg among 60 cases utilized in 55 (91.7%), 4 (6.7%), and 1 (1.6%), respectively. Of the total, 32 (53.3%) patients had Grade 3-4 toxicity. Palbociclib received in first-line, second-line, and subsequent lines by 20 (33.3%), 22 (36.7%), and 18 (30%), respectively. Out of 32 (53.3%) cases, which developed, grade 3–4 palbociclib related toxicity, the incidence of hematological and non-hematological toxicities was 26 (43.3%) and 6 (10%), respectively. Dose reduction, treatment discontinuation, and hospitalization due to toxicity reported in 30 (50%), 5 (8.3%), and 2 (3.3%), respectively. Febrile Neutropenia was the most prevalent adverse event found in 23 (38.3%) cases. Conclusion: Palbociclib shows clinical utility in elderly HR+/Her2-Her2-MBC patients; however, close monitoring is necessary due to frequent adverse effects requiring dosage adjustment or dissection. These findings support individual dose strategies to increase drug tolerance while maintaining medical efficacy in the old population.