Palbociclib combined with endocrine therapy in heavily pretreated HR +/HER2 - advanced breast cancer patients: Results from the compassionate use program in Spain (PALBOCOMP)
Luis Manso 1 , Cristina Hernando 2 , María Galán 3 , Mafalda Oliveira 4 , Miguel A Cabrera 5 , Raquel Bratos 6 , César A Rodríguez 7 , Manuel Ruiz-Borrego 8 , Salvador Blanch 9 , Antonio Llombart-Cussac 10 , Juan I Delgado-Mingorance 11 , Iñaki Álvarez-Busto 12 , Isabel Gallegos 13 , Lucía González-Cortijo 14 , Serafín Morales 15 , Elena Aguirre 16 , Blanca A Hernando 17 , Ana Ballesteros 18 , José E Alés-Martínez 19 , Cristina Reboredo 20 , Amparo Oltra 21 , María González-Cao 22 , Marta Santisteban 23 , Diego Malón 24 , Isabel Echeverría 25 , Elisa García-Garre 26 , Estela Vega 27 , Sònia Servitja 28 , Raquel Andrés 29 , Carlos E Robles 30 , Rafael López 31 , Elena Galve 32 , María J Echarri 33 , Marta Legeren 34 , Fernando Moreno 35
Background: This study evaluated efficacy and safety of palbociclib, a CDK4/6 inhibitor, in heavily-pretreated hormone receptor-positive and human epidermal growth factor receptor 2-negative (HR+/HER2-) metastatic breast cancer (mBC) patients during the compassionate use program in Spain from February 2015 to November 2017.
Patients and methods: Patient data were collected retrospectively from 35 hospitals in Spain. Patients with HR+/HER2- mBC who had progressed on ≥4 treatments for advanced disease were eligible.
Results: A total of 219 patients received palbociclib in combination with aromatase inhibitors (110; 50.2%), fulvestrant (87; 39.7%), tamoxifen (8; 3.6%) or as single agent (10; 4.6%). Mean age of the patients was 58 years; 31 patients (16.1%) were premenopausal and 162 (83.9%) were postmenopausal at the beginning of treatment with palbociclib. Patients had received a median of 3 previous lines of endocrine therapy (ET) for advanced disease. Real-world tumor response (rwTR) and clinical benefit rate were 5.9% (n = 13) and 46.2% (n = 101), respectively. The median real world progression-free survival (rwPFS) was 6.0 months (95% CI 5.7-7.0) and the median overall survival was 19.0 months (95% CI 16.4-21.7).
Subgroup analysis revealed a significant difference in median rwPFS in patients treated with palbociclib plus fulvestrant depending on the duration of prior treatment with fulvestrant monotherapy (>6 versus ≤6 months; HR 1.93, 95% CI 1.37-2.73, p < 0.001). The most frequently reported toxicities were neutropenia, asthenia, thrombopenia and anemia.
Conclusions: Palbociclib can be an effective and safe treatment option in patients with heavily pretreated endocrine-sensitive mBC, especially in those with longer PFS to previous ET.