Abstract P4-01-28: PALBOSPAIN: OBSERVATIONAL ANALYSIS OF FIRST-LINE THERAPY WITH PALBOCICLIB IN PATIENTS WITH HR+/HER2- METASTATIC BREAST CANCER (MBC) IN REAL-LIFE CONDITIONS
Authors: Martínez-Jáñez Noelia , Ezquerra Meritxell Bellet , Henao Fernando , Manso Luis , Antón Antonio , Zamora Pilar , Murillo Serafin Morales , Tolosa Pablo , Andrés Raquel , Calvo Lourdes , Galve Elena , Lopez Rafael , de la Peña Francisco Ayala , López-Tarruella Sara , Boronat Laia , Martos Tamara , Chacón J. Ignacio , Álvarez Isabel , de la Haba-Rodríguez Juan , Antón Fernando Moreno 
Published: March 2023

INTRODUCTION AND OBJECTIVES Palbociclib associated with hormone therapy (HT) has shown significant benefit in progression-free survival (PFS) and response rate versus HT alone in patients with HR+, HER2- MBC. The PALBOSPAIN study evaluates the efficacy and safety of palbociclib treatment under real-life conditions. The main objective of the study was to assess PFS, and secondary objectives were overall survival (OS), response rate, time to next line of treatment, percentage of dose reduction and safety.

MATERIAL AND METHODS This is an observational, ambispective, multicenter, nation-wide study. Patients diagnosed with HR+/HER2- MBC who had started first-line treatment with palbociclib between November 2017 and November 2019 were included. Patients treated within a clinical trial were excluded, as were those who had received any previous systemic treatment for advanced disease.

RESULTS 762 patients from 35 centers were included. 79% (n=600) were postmenopausal, 54.9% (n=418) had visceral disease, and 30.6% (n=233) had de-novo metastatic disease. Palbocliclib was combined with an aromatase inhibitor in 69.6% of patients and fulvestrant in 30.2% Four groups were established to assess efficacy (table 1): overall population; patients with de-novo metastatic disease (cohort A); patients relapsing &gt;12 months after the end of adjuvant hormonal therapy (cohort B); and patients relapsing within 12 months after the end of adjuvant hormonal therapy (cohort C). Median PFS was 24 months (CI 95%; 25-27) overall and 28 (IC 95%; 23-39), 29 (IC 95%;25-35) and 14 months (IC 95%;11-17) for cohorts a, B and C, respectively. Median overall survival was 42 months (40-NA). The most common side effects were neutropenia (71.3%, grade 3-4 in 52.5%, no episodes of febrile neutropenia), fatigue (38.6%), leucopenia (29.8%), anemia (28.9%), articular pain (19%), and thrombocytopenia (2,2%). 49% (n=385) of patients required dose reduction of palbociclib (one level in 27.6% and two levels in 21.4%).

CONCLUSION In the first two years after its approval in Spain, palbociclib in first line of HR+/HER2- MBC in real-life conditions yielded PFS and safety results comparable to those of PALOMA 2 and PALOMA 3 clinical trials. OS results were poorer, although the population included in this retrospective study is heterogeneous and median survival values have not been reached in some subgroups.

Table 1. Efficay results of palbociclib in real world

Citation Format: Noelia Martínez-Jáñez, Meritxell Bellet Ezquerra, Fernando Henao, Luis Manso, Antonio Antón, Pilar Zamora, Serafin Morales Murillo, Pablo Tolosa, Raquel Andrés, Lourdes Calvo, Elena Galve, Rafael Lopez, Francisco Ayala de la Peña, Sara López-Tarruella, Laia Boronat, Tamara Martos, J. Ignacio Chacón, Isabel Álvarez, Juan de la Haba-Rodríguez, Fernando Moreno Antón. PALBOSPAIN: OBSERVATIONAL ANALYSIS OF FIRST-LINE THERAPY WITH PALBOCICLIB IN PATIENTS WITH HR+/HER2- METASTATIC BREAST CANCER (MBC) IN REAL-LIFE CONDITIONS [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-01-28.