Since its approval in Europe in November 2016, the CDK4/6 inhibitor palbociclib (PA) has been widely used for treatment of hormone receptor-positive (HR+) metastatic breast cancer (MBC). This study evaluates as a quality assurance measure the treatment with PA at the breast center of the University of Munich (LMU).
Patients (pts) who started PA-treatment for HR+ MBC between 9/16-9/18 (n = 75) were retrospectively included. Data were obtained from pt medical files in 12/18 (54.7 % still under ongoing therapy). Statistical analyses were performed using Chi-squared-test and Kaplan-Meier-estimates.
Median age was 62 years; the main localization of metastases was bone (77.3 % of all pts, lymphatic 41.3 %, liver 36 %). 72 % received PA as 1st or 2nd line therapy for MBC, most had a history (adjuvant or in MBC) of at least one endocrine therapy (78.7 %) or chemotherapy (64.4 %). Most pts (50.7 %) received fulvestrant (letrozole 44 %, exemestane 5.3 %) and a starting dose of 125 mg PA (77.3 %). Dose reduction (DR) to 100 or 75 mg PA occurred in 52.1 % and 24 % of all pts - mainly due to grade 3 neutropenia (shown in 64 % of all pts, reason for 86.7 % of 1st and 88.9 % of 2nd DR). Main non-hematological complications were fatigue (41.3 %) and gastrointestinal symptoms (40 %), especially in the first therapy cycles with improvement over time. Complications and need for DR did not significantly correlate with localization of metastasis, therapy line or prior therapies. 45.3 % stopped PA-therapy during the observation period, mainly (85.3 %) due to progression. Median progression-free survival (PFS) estimated by Kaplan-Meier was 16 (95 % CI 9.1 - 22.9) months. Estimated median PFS was significantly shorter in pts with liver metastasis (7 months, without liver metastasis median not reached, p = 0.01), if PA was used in 3rd line or later (9 vs. 18 months, p = 0.01) and in pts receiving fulvestrant compared to letrozole (11 months, in letrozole therapy median not reached; p = 0.04).
Our data show that in daily clinical use, PA is a well-tolerated therapy for MBC with grade 3 neutropenia as the main complication. Pts with liver metastasis should be monitored carefully as progression seemed to occur earlier in this group.
Department of Obstetrics and Gynaecology, Breast Center and CCC Munich, University Hospital, LMU Munich.
Has not received any funding.
A. Hester: Research grants: The “Walter Schulz Stiftung”; Speaker, advisory board honorarium: Roche, Germany; Travel and accommodation costs, honorarium for symposium: Pfizer. T. Degenhardt: Honoraria for consultant activity: Pfizer; Travel support: Celgene S. Mahner: Research support, advisory board, honoraria, travel expenses: AstraZeneca, Clovis, Medac, MSD, PharmaMar, Roche, Sensor Kinesis, Tesaro, Teva. N. Harbeck: Honoraria for consulting / Lectures: Novartis, Lilly, Pfizer. R. Wuerstlein: Honoraria, consulting: Agendia, Amgen, AstraZeneca, BI, Carl Zeiss, Celgene, Daiichi-Sankyo, Eisai, Genomic Health, GSK, Hexal, Lilly, MSD, Mundipharma, NanoString, Novartis, Odonate, Paxman, Palleos, Pfizer, Pierre Fabre, PBYI, Riemser, Roche, Sandoz/Hexal, SGEN, Tesaro, Teva. All other authors have declared no conflicts of interest.