Conclusions
This study demonstrates the effectiveness and tolerability of palbociclib within the first cohort of patients with HR-positive/HER2-negative advanced/MBC treated in routine clinical practice in the UK NHS prior to the funding agreement. It highlights that patients with de novo MBC appear to derive greater benefit than those with relapsed MBC and that delaying the initiation of palbociclib may compromise clinical efficacy. Patient access schemes like the IPP can bridge the gap between regulatory approval and NHS funding for new medicines, providing benefits to patients as well as facilitating the collection of data to evaluate real-world outcomes.