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Dosing Patterns and Economic Burden of Drug Wastage Among Postmenopausal Women With HR+/HER2− Metastatic Breast Cancer Receiving Palbociclib

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Dosing Patterns and Economic Burden of Drug Wastage Among Postmenopausal Women
with HR+/HER2− Metastatic Breast Cancer Receiving Palbociclib

• Approximately 80% of breast cancers (BCs) are diagnosed as positive for estrogen/progesterone
hormone receptor (HR+) and negative for human epidermal growth factor receptor 2 (HER2−),
called HR+/HER2− BC1,2
• While the vast majority of BCs are detected in early stage, around 30% of BCs will eventually
develop into metastatic BC (mBC)3
• Recently, the management of HR+/HER2− mBC has significantly advanced with the approval of
novel targeted therapies—cyclin-dependent kinases 4/6 (CDK4/6) inhibitors palbociclib, ribociclib,
and abemaciclib4-6
• As for many oncology drugs, the dosage of CDK4/6 inhibitors may need to be adjusted over time.7,8
However, based on the dosage form and strengths available, dose modification may lead to drug
wastage for some treatments when the dose cannot be split or saved for later use
• This is the case for palbociclib, which is available in capsules that come in three different strengths,
125 mg, 100 mg, and 75 mg. The recommended starting dose is 125 mg/day and, should a dose
reduction be required, the label recommends a first dose reduction to 100 mg/day and, if needed,
a second dose reduction to 75 mg/day4
• Drug wastage may arise given that the palbociclib dose cannot be modified without requiring a new
prescription fill
• To describe dosing patterns and estimate the economic burden of drug wastage associated with
dose modifications in postmenopausal women with HR+/HER2− mBC who received palbociclib
Data Source
• Truven Health Analytics MarketScan® Commercial Claims and Encounters, and Medicare
Supplemental databases (January 1, 2006, to December 31, 2015)
• Data are de-identified and comply with the confidentiality requirements of the Health Insurance
Portability and Accountability Act

• Lines of therapy for mBC were constructed by identifying changes in treatment regimens over
time (i.e., discontinuation [treatment interruption of ≥90 days], treatment add-on, treatment drop
[discontinuation of one agent—for regimens combining multiple agents], or treatment switch)
• All agents received during the first 28 days of the line of therapy constituted the treatment
regimen—could include a single agent or combine multiple agents
Dose modification
• Dose modification was defined as a dose decrease/increase of ≥25 mg daily compared to the
preceding dose
• Crude dose modification rates during the studied line of therapy were reported
Drug wastage
• The costs of drug wastage were estimated by multiplying the number of days with drug wastage
(i.e., days with overlapping palbociclib prescriptions due to dosage change) by the average cost
reimbursed from a payer’s perspective for one unit of palbociclib—costs of drug wastage were
reported in 2015 USD
• Results were reported separately for patients treated with palbociclib in first, second, or third line
of therapy

• The majority of patients started palbociclib on the recommended 125 mg dose: 89.7% of patients
in first line, 87.3% in second line, and 94.2% in third line

• Dose modification rates varied across lines of therapy

• Over an average period of approximately 4 months:
–– 38 (17.8%) patients who used palbociclib in first line, 49 (31.2%) in second line, and 42 (35.0%) in third line
had a dose modification
–– During the first, second, and third line, drug wastage resulted in an average cost of $4,376, $4,740, and
$2,592 per patient, respectively
• Dose modifications and drug wastage were estimated based on prescription fills—however, claims
data do not include information to confirm that the drug was consumed by the patient
• Drug wastage was assessed based on dose modification and number of overlapping days.
However, there is no information in claims data to confirm if the drug was disposed after the dose
change or kept for later use
• Given that there is no information in claims data to directly identify women with HR+/HER2− mBC,
or postmenopausal status, patients were identified using an algorithm based on treatment
and procedures
• The generalizability of the study is limited to the patient population and time period studied

Discussion and Conclusions
• Drug wastage in oncology is the focus of growing concerns
• Among a sample of patients with HR+ HER2− mBC, this study showed that drug wastage due
to palbociclib dose modification is associated with a substantial economic burden for payers
• Treatment options with more flexible dosing may help reduce the costs associated with
drug wastage
–– For example, instead of requiring a new prescription, the dose of ribociclib can be modified by advising
the patient to alter the number of tablets taken daily (e.g., from 3 tablets of
200 mg to 2 tablets of 200 mg)
–– While abemaciclib is also available in multiple strengths, the recommended starting dose and dose
modification may be less flexible (e.g., from 150 mg bid to 100 mg bid, or from 200 mg bid to 150 mg bid).
Studies assessing abemaciclib treatment patterns would be needed to assess potential drug wastage

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