The combination of palbociclib with hormone therapy significantly increases progression free survival (PFS) compared with hormone therapy in first and second treatment line of HR+ HER2- metastatic breast cancer (MBC). However, the activity and security of palbociclib in MBC patients progressing after multiple treatment lines, has not been tested in clinical trials.
Spanish compassionate use program of palbociclib enabled drug access to patients with HR+/HER2- MBC previously treated with at least 4 treatments for advanced disease and adequate organ function (bone marrow reserve, QTc interval and renal/liver function). Patients received palbociclib 125 mg once daily for 3 weeks followed by 1 week off alone or in combination with endocrine therapy (tamoxifen, fulvestrant, aromatase inhibitor and LHRH-agonists in premenopausal patients).
Between February 2015 and November 2017, 385 patients received treatment with palbociclib. Considering the dispersion of the centers that hindered the analysis, PALBOCOMP study has considered only those that included ≥ 3 patients in the compassionate use program. We report the results of the 70 first patients analyzed. The median age was 46.1 years (range 33.5–58.7 years) at the time of inclusion. 67 (95.7%) and 65 (92.9%) patients had received previous hormonal treatment and chemotherapy for advanced disease respectively. Concomitant hormonal therapy was fulvestrant in 55.7% patients and aromatase inhibitors in 34.3%. Best objective response was partial or complete response in 3 patients (4.3%), stable disease in 25 patients (35.7%) and progressive disease in 33 patients (47.1%) Evaluation of response was not available in 9 patients (12.9%) at the moment of the analysis. Median progression free survival was 5 months (95% CI 3.2-6.8 months).
Palbociclib in combination with endocrine therapy shows encouraging activity in heavily pretreated endocrine-resistant HR+ MBC.
Fundación para la Investigación Biomédica Hospital Clínico San Carlos.
Pfizer.
L. Manso: Consultant or advisory role: Pfizer, Tesaro, AstraZeneca, Roche, Novartis, Celgene; Research funding: Tesaro. Speaking: Roche, AstraZeneca, Novartis. M. Gonzalez: Advisory role: BMS, Pierre Fabre; Speaker: AstraZeneca. D. Malón: Advisory role: Roche, Novartis, Ipsen, Pfizer, BMS, MSD, Eisai; Travel expenses: Roche, Novartis, MSD, BMS. J.E. Ales: Travel expenses: Pfizer. F. Moreno: Advisory role: Roche, Pfizer, Novartis, AstraZeneca, Eisai; Travel expenses: Roche, Pfizer. All other authors have declared no conflicts of interest.