Abstract P6-16-05: Early utilization pattern of palbociclib 1 year post-approval in the United States
Authors: Kish JK , Ward MA , Garofalo D , Ahmed HV , McRoy L , Laney J , Zanotti G , Yu H-T , Feinberg BA 
Published: March 2017

Background

Palbociclib was approved in the U.S. in February 2015 for the treatment of advanced/metastatic breast cancer (MBC) in combination with letrozole as initial endocrine based therapy for post-menopausal women with ER+/HER2- disease. We examined the demographic, clinical characteristics and treatment patterns of patients initiating palbociclib (PAL) + letrozole (LET) in real-world, community oncology practices.

Methods

This was a retrospective observational study of female breast cancer patients identified in the Navigating Cancer (NC) EMR database. The NC database collects EMR data, in both structured and unstructured fields (patient/clinical progress notes), from over 975 oncology and hematology providers across more than 50 locations in 25 states. Female patients with record of treatment with PAL after 01/31/2015 were selected. Combination treatment with LET was defined as having a record for LET within 30 days of the PAL prescription. Line of therapy (LOT) was assessed from the date of metastatic diagnosis and assigned by evaluating treatment plans pre-and post PAL initiation. Bi-monthly cohorts were constructed based on the month of initiation of PAL from 02/01/2015-01/31/2016. Interim results are presented; data from an additional three months of follow-up (through 03/31/2016) are pending.

Results

Overall, 931 unique patients were identified as having initiated PAL treatment. Of those, 608 (65.3%) received PAL + LET. Mean follow-up was relatively short at 5.4 mo (SD=3.5). Confirmed ER+/HER2- was observed in 71.6% of patients and 50.3% were age ≥65, mean age was 64.3 yrs. Of patients with available ECOG-PS at treatment initiation (n=424): 0/1=78.5%, 2=17.5% and 3=4.0%. Of patients with a known starting dose (n=418), 69.9% initiated with PAL 125mg, 22.0% at 100mg and 8.1% at 75mg. Compared to women &lt; 65, women ≥ 65 were more often started with 100mg (25.4% vs. 18.9%) and 75mg (10.0% vs 6.5%). Any dose reductions were observed in 20.6% of patients (21.5% of patients receiving 125mg). During the year following approval, 39.8% of patients initiated PAL + LET at LOT1, 15.6% at LOT2, 13.0% at LOT3 and 31.6% at LOT4+, following MBC diagnosis. Over time the proportion of late use (LOT4+) declined from 39.7% in Feb/Mar '15 to 23.9% in Dec '15/Jan '16 with more patients utilizing in LOT3 (from 7.9% in Feb/Mar '15 to 19.5% in Dec '15/Jan '16).

Number of Patients Initiating PAL + LET by LOT and Month. AllFeb/Mar '15Apr/May '15Jun/Jul '15Aug/Sep '15Oct/Nov '15Dec'15/Jan '16N (%)608(100)63(10.4)108(17.8)125(20.6)108(17.8)91(14.5)113(18.6)LOT1 (%)242(39.8)23(36.5)45(41.7)53(42.4)45(41.7)33(36.3)43(38.1)LOT2 (%)95(15.6)10(15.9)12(11.1)19(15.2)15(13.9)18(19.8)21(18.6)LOT3 (%)79(13.0)5(7.9)10(9.3)18(14.4)12(11.1)12(13.2)22(19.5)LOT4+ (%)192(31.6)25(39.7)41(38.0)35(28.0)36(33.3)28(30.8)27(23.9)

Conclusions

There was a trend toward earlier utilization of PAL + LET from Feb-Jul '15, an increase in later use during Aug/Sep '15, and a return towards earlier use in subsequent cohorts reaching the lowest proportion of LOT 4+ use observed in Dec '15/Jan '16. After a mean follow-up of 5.4 mo, 21.5% of patients receiving the 125 mg dose had a dose reduction. Final results, with additional follow-up, will be presented at conference.

Citation Format: Kish JK, Ward MA, Garofalo D, Ahmed HV, McRoy L, Laney J, Zanotti G, Yu H-T, Feinberg BA. Early utilization pattern of palbociclib 1 year post-approval in the United States [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-16-05.