Advances in the management of metastatic breast cancer (MBC) have increased rapidly in recent years; however, there is little information on treatment sequencing patterns of oncologic agents or on the cost that these regimens incur.

To help address this gap in knowledge, researchers conducted an economic evaluation of data from January 1, 2011, to May 31, 2021, obtained from the nationwide Flatiron Health database, which is an electronic health record–derived deidentified database that houses longitudinal information from about 800 sites of car, including community and academic practices sites. The purpose of this study was to identify treatment patterns by MBC subtype and associated oncologic and supportive drug costs based on cost data from the healthcare sector and Medicare.

In particular, investigators were interested in identifying the frequency of different drug regimens in order of preference based on MBC subtype. A particular focus was placed on the first five lines of treatment. Investigators also examined the mean medical costs of anticancer and supportive care regimens based on MBC subtype.

To have their Flatiron Health data included in the study, women had to be aged 18 years or older; be diagnosed with MBC; have generated at least 6 months of follow-up data; had their hormone-receptor (HR) status and their human epidermal growth factor receptor 2 (HER2, now referred to as ERBB2) status known; and were administered at least one documented line of therapy.

The study results were reported as treatment patterns (which included only the first five lines of sequential therapy for MBC and limited drug regimens to those that captured 73% of all unique first-line therapies and no more than 105 unique treatment regimens per subtype and line of therapy); therapy duration/frequency and drug dosage (which divided drugs into oral whose duration of therapy was the time between the start and end date of treatment and nonoral medications, whose total number of treatments were based on drug administrative dates); annual costs, which was cost per year since MBC diagnosis, were calculated based on the treatment administered in the previous 12 months; use of supportive drugs (including bone marrow stimulating factors, chemoprotective agents, and antiemetics that cost $100 or more per administration); and cost estimation (which was based on either average whole price using McKesson’s pricing information or Centers for Medicare & Medicaid Services (CMS) Medicare Part B payment limit data for Part B–covered drugs).

Given that oral medications are not covered by Medicare part B, mean spending per dosage unit in 2019 was based on the CMS Medicare Part D Drug Spending Dashboard. Prices were indexed to October 2021, and 2021 prices were applied to all years. A standard body surface area of 1.8 m2 and a weight of 80 kg was used for dose calculations. When both a brand and generic were available for a drug product, the generic pricing was utilized.

Total overall drug costs were calculated using patient-level data. Calculations were performed based on mean and median price per patient per line for each regimen and were classified by MBC subgroup and line of therapy. Costs were also calculated for each drug regimen to determine their contribution to the total price for the MBC subgroup and line of therapy.

A total of 15,215 patients with a median age of 64 years were included in the study. This group was ethnically diverse with whites comprising 64.4%, African Americans comprising 11.7%, and Asians making up 2.4% of the group. Based on hormonal and ERRB2 status, women were divided into four groups: 66.9% were HR+/ERBB2-, 18.3% were HR+/ERBB2+, 5.3% were HR-/ERBB2+, and 9.6% had triple negative MBC (TNMBC).

Details of the various regimens are beyond the scope of this article and the reader is encouraged to visit the study’s supplemental content for specifics. Different drug regimens ranged from 22 to 105 based on MBC subtype. Across the years, the most frequent first-line therapies were anastrozole (14.5%) for the HR+/ERBB2-; docetaxel, pertuzumab, and trastuzumab for the HR+/ERBB2+ (12.6%) and for HR-/ERBB2+ (18.2%); and capecitabine (19.0%) for TNMBC. Supportive care drugs were most often used in TNMBC (40.2%-46.1% of patients).

The most expensive mean first-line regimen was for those with HR-/ERBB2+ MBC disease, with a 1-year mean cost of $131,548, followed by $118,062 for HR-/ERBB2+ MBC and $46,712 for HR+/ERBB2- MBC; the least expensive regimen was for TNMBC at $26,150 reflecting the limited treatment options for this subtype of BC.

The cost for supportive-care regimens decreased over time. When the cost for first-line therapy was added to the cost for the supportive-care regimens, HR-/ERBB2+ MBC was still associated with the highest total treatment cost at $334,812, followed again by HR-/ERBB2+ at $284,609 and HR+/ERBB2- MBC at $104.774; TNMBC’s total treatment costs were only $54,355.

As pharmacists are involved in drug procurement, budgeting, dispensing, and counseling on the chemotherapeutic regimens, this article provides valuable insight that can assist oncology pharmacists in the management of their patients with MBC.

The content contained in this article is for informational purposes only. The content is not intended to be a substitute for professional advice. Reliance on any information provided in this article is solely at your own risk.

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