The United States Food and Drug Administration has approved palbociclib for patients with advanced hormone receptor-positive and HER2-positive breast cancer, making the treatment available ahead of European regulatory decisions.
In Europe, the new indication remains pending regulatory evaluation, meaning that the combination therapy is not yet generally available to patients in Spain.
The decision by the US Food and Drug Administration allows palbociclib to be used alongside trastuzumab, with or without pertuzumab, and endocrine therapy. The approval applies to patients with locally advanced or metastatic hormone receptor-positive (HR+) and HER2-positive (HER2+) breast cancer whose condition has not progressed after initial treatment with chemotherapy and anti-HER2 therapy.
Clinical Trial Shows Extended Survival
The regulatory approval is based on results from the pivotal phase III Patina trial, also known as AFT-38. The study demonstrated that adding palbociclib to standard first-line maintenance therapy extends progression-free survival by more than 15 months compared to standard care alone.
Patients who received palbociclib achieved a median progression-free survival of 44.3 months, compared with 29.1 months for those on standard maintenance therapy alone. This represents a 24 percent reduction in the risk of disease progression or death, with no new safety signals identified during the trial.
Hormone receptor-positive and HER2-positive tumors account for approximately 10 percent of all breast cancer cases. Hormone receptor-positive cells depend on hormones such as estrogen to grow, while HER2-positive cells produce excessive amounts of the HER2 protein, which drives aggressive tumor growth. Although treatment advances have improved survival, resistance to anti-HER2 therapies and endocrine treatments remains a central clinical challenge in advanced stages of the disease.
Palbociclib is a targeted medication belonging to a class of drugs known as CDK4/6 inhibitors. These drugs function by inhibiting cyclin-dependent kinases 4 and 6, key enzymes that cancer cells require to divide and replicate. By halting cell cycle progression, the combination therapy aims to sustain disease control for a longer period.
International Study Leadership
The Patina trial investigated whether adding palbociclib to anti-HER2 and endocrine therapy, following four to eight cycles of induction chemotherapy, could delay disease progression. Prior to the publication of the final data, clinical observers had noted that the study was expected to mark a significant milestone in treating hormone receptor-positive, HER2-positive breast cancer.
Dr. Otto Metzger, principal investigator of Patina and associate medical director of international strategic initiatives at the Dana-Farber Cancer Institute, said in a statement that the trial answered an important clinical question by establishing that adding palbociclib to standard maintenance therapy can significantly prolong progression-free survival in this patient group. He added that the regulatory approval translates those scientific findings into a concrete new treatment option for patients.
Dr. Aleix Prat, a member of the trial steering committee and director of the Clínic Barcelona Comprehensive Cancer Centre, said the approval by the US regulator confirms the clinical relevance of the Patina results. He highlighted that extending the period without disease progression by around 15 months represents a benefit of major clinical importance for patients.
The study was conducted between June 2017 and July 2021 across 109 clinical centers in the United States, Europe, Australia, and New Zealand, enrolling 518 patients in total. Led internationally by Alliance Foundation Trials, the trial results were published in The New England Journal of Medicine.
Spanish Research Participation
Spanish research groups had a significant role in the trial, which was coordinated across Spain and Portugal by the academic research group SOLTI. A total of 23 active centers participated across the Iberian peninsula, including 19 in Spain and four in Portugal. Together, they enrolled 122 patients, with 113 recruited in Spain and nine in Portugal, making Spain the third largest contributor of trial participants worldwide.
Key medical figures oversaw the trial in Spain. Dr. Santiago Escrivá, a medical oncologist at Hospital Universitario Vall d'Hebron and researcher in the Breast Cancer Group at the Vall d'Hebron Institute of Oncology (VHIO), acted as the leading patient recruiter in Spain. Dr. Xavier González, medical oncologist and department head at the Instituto Oncológico Dr. Rosell at Hospital Universitario General de Cataluña, served as medical supervisor for Spain and Portugal to ensure clinical supervision and scientific rigor throughout the trial.
Dr. Eva Ciruelos, vice president of SOLTI and principal investigator for the study in Spain, said Patina serves as an example of the value of international collaboration between academic research groups. She explained that SOLTI participated in all aspects of the study, from initial design and setup to patient recruitment, allowing patients in Spain to access the therapeutic strategy through the trial while European regulatory clearance remains pending.
