palbociclib

palbociclib
Name	Palbociclib
Tradename	Ibrance
Synoyms	PD-0332991
Routes of administration	Oral
Legal status	Prescription-only
Metabolism	Hepatic (CYP3A)
Elimination half-life	~29 hours
CAS number	571190-30-2

palbociclib Palbociclib is a small-molecule cyclin-dependent kinase inhibitor used in oncology. It is primarily prescribed for certain hormone receptor–positive malignancies and is administered orally as part of combination regimens. The drug’s development involved collaborations among academic institutions and pharmaceutical companies and it has been evaluated in multiple phase II and phase III trials.

Medical uses

Palbociclib is indicated for treatment of hormone receptor–positive, human epidermal growth factor receptor 2–negative advanced or metastatic breast cancer in combination with endocrine therapies like fulvestrant and letrozole. Trials led by investigators at institutions such as Dana-Farber Cancer Institute, Memorial Sloan Kettering Cancer Center, University of Texas MD Anderson Cancer Center, Mayo Clinic, and Massachusetts General Hospital informed its use. Endorsements and guideline placements were considered by bodies including National Comprehensive Cancer Network, European Society for Medical Oncology, American Society of Clinical Oncology, National Institute for Health and Care Excellence, and regulatory agencies like the United States Food and Drug Administration.

Patients selected for therapy typically have progressed on prior endocrine therapy; pivotal studies compared combinations versus monotherapy in populations enrolled at centers affiliated with Johns Hopkins Hospital, Vanderbilt University Medical Center, Stanford University School of Medicine, University of California, San Francisco, and international sites including Royal Marsden Hospital, Gustave Roussy, Seoul National University Hospital, and Peter MacCallum Cancer Centre.

Mechanism of action

Palbociclib is a selective inhibitor of cyclin-dependent kinases 4 and 6, which regulate the G1 to S phase transition via phosphorylation of retinoblastoma protein. Studies from laboratories at Harvard Medical School, Yale School of Medicine, Princeton University, MIT, and Cold Spring Harbor Laboratory characterized its binding and selectivity profiles. Preclinical models from teams at Scripps Research Institute, Broad Institute, Wellcome Sanger Institute, Weizmann Institute of Science, and Riken demonstrated cell cycle arrest in sensitive tumor lines, with mechanistic insights cited alongside work on cyclin D–CDK complexes from researchers at Rockefeller University, Karolinska Institutet, University of Cambridge, and University of Oxford.

Resistance mechanisms studied by groups at Institut Curie, National Cancer Institute, Dana-Farber Cancer Institute, and German Cancer Research Center implicate alterations in RB1, cyclin E amplification, and other pathway adaptations similar to findings in reports involving European Molecular Biology Laboratory, Cold Spring Harbor Laboratory, and Fred Hutchinson Cancer Research Center.

Pharmacology

Pharmacokinetic characterization involved clinical pharmacology centers at Mayo Clinic, Cleveland Clinic, King's College Hospital, Imperial College London, and Addenbrooke's Hospital. Palbociclib is absorbed orally, exhibits hepatic metabolism predominantly via CYP3A (studied in laboratories at University of Washington, University of North Carolina at Chapel Hill, and Monash University), and has an elimination half-life supporting once-daily dosing. Drug–drug interaction evaluations referenced CYP3A modulators studied in trials coordinated with European Medicines Agency reviewers and pharmacology groups at University College London.

Dose-finding and formulation development were conducted with input from clinical pharmacologists at Pfizer Inc. and academic collaborators at University of Pennsylvania, University of Michigan, Ohio State University Comprehensive Cancer Center, and international pharmacology units at Tokyo Medical University, National University of Singapore, and Seoul National University.

Adverse effects

Common adverse events identified in multicenter studies at MD Anderson, Memorial Sloan Kettering Cancer Center, St. Bartholomew's Hospital, Hospital Clínic de Barcelona, and Karolinska University Hospital include neutropenia, leukopenia, anemia, fatigue, nausea, stomatitis, diarrhea, and alopecia. Serious adverse events documented in safety reviews overseen by panels from FDA Oncology Center of Excellence, EMA Committee for Medicinal Products for Human Use, Health Canada, and Therapeutic Goods Administration include febrile neutropenia and opportunistic infections; monitoring practices were established in guidelines by ASCO and ESMO. Laboratory abnormalities and myelosuppression management strategies were informed by hematology groups at Royal College of Physicians, European Hematology Association, and American Society of Hematology.

Case reports and pharmacovigilance signals were collected via collaborations with networks including Sentinel Initiative, VigiBase, ClinicalTrials.gov, and registries maintained by institutions such as Duke University Hospital and University of Toronto.

Contraindications and precautions

Contraindications focus on hypersensitivity to the active substance and severe myelosuppression, as outlined in labeling assessed by FDA, EMA, Health Canada, Swissmedic, and Japanese Pharmaceuticals and Medical Devices Agency. Precautions include regular complete blood counts informed by practice recommendations from NCCN, ASCO, ESMO, Royal College of General Practitioners, and specialty societies at Singapore Medical Association and Hong Kong College of Physicians. Considerations for hepatic impairment, pregnancy, and lactation were addressed in pharmacology reviews at NIH, European Medicines Agency, and ethics committees at major cancer centers including Dana-Farber and Memorial Sloan Kettering.

Drug interaction warnings with strong CYP3A inhibitors and inducers were developed drawing on work by clinical pharmacology groups at University of Toronto, University of British Columbia, Monash University, and Karolinska Institutet.

History and development

Discovery and early development occurred within collaborative programs linking Pfizer Inc. research teams and academic laboratories at Duke University, University of California, San Diego, Massachusetts Institute of Technology, and University of Cambridge. Preclinical characterization referenced studies from institutions such as Scripps Research Institute, Broad Institute, Wellcome Trust Sanger Institute, and European Molecular Biology Laboratory. Phase I–III trials were led by consortia including investigators from MD Anderson, Vanderbilt, Mayo Clinic, Royal Marsden, and Gustave Roussy with clinical endpoints published in journals affiliated with editorial boards at New England Journal of Medicine, Lancet Oncology, Journal of Clinical Oncology, Nature Medicine, and Cancer Research.

Key investigators, steering committees, and trial sponsors involved named academic leaders and cooperative groups including SWOG, EORTC, Alliance for Clinical Trials in Oncology, and NCI networks. Intellectual property, licensing, and commercialization negotiations occurred between Pfizer and regulatory/legal teams coordinating with agencies including European Commission and U.S. Department of Health and Human Services.

Regulatory approval and commercial availability

Regulatory approvals were granted by bodies such as the United States Food and Drug Administration and European Medicines Agency, with national approvals from Health Canada, Therapeutic Goods Administration, Swissmedic, and Pharmaceuticals and Medical Devices Agency in Japan. Market authorization and reimbursement decisions involved assessment by NICE, IQWiG, Haute Autorité de Santé, and national health technology assessment agencies in Germany, France, Italy, Spain, and Australia. Distribution and commercial partnerships were executed by Pfizer Inc. and affiliated distributors working with hospital pharmacies at institutions including Johns Hopkins Hospital, Cleveland Clinic, Seoul National University Hospital, Royal Marsden Hospital, and Peter MacCallum Cancer Centre.

Category:Antineoplastic agents