3477 - Impact of adjuvant trastuzumab emtansine (T-DM1) on incidence of metastatic breast cancer (mBC): an epidemiological model of patients with HER2-positive breast cancer (BC) who did not achieve pathological complete response (pCR) after neoadjuvant treatment (non-pCR)

Background

Progression from early BC (eBC) to mBC creates a substantial burden for pts and healthcare systems. The KATHERINE trial showed adjuvant T-DM1 reduced the risk of disease recurrence or death by 50% vs trastuzumab (T) in pts with HER2-positive eBC with residual disease after neoadjuvant tx. The population level impact of T-DM1 on preventing relapsed mBC cases of HER2-positive, non-pCR eBC in 5 European countries (EU5) was estimated.

Methods

An epidemiological model was developed and data from observational and clinical trial studies were used to inform BC variables (Table). Weighted averages of non-pCR rates by neoadjuvant tx and hormone receptor (HR) subtype were calculated and extrapolations from KATHERINE data were used to model disease progression and death.Table:

193P Epidemiology model variables and sources to determine prevented relapsed mBC cases over the time period 2020-2029

EU5 = France, Germany, Italy, Spain, United Kingdom (UK) ESMO, European Society for Medical Oncology; SEER, Surveillance, Epidemiology, and End Results.

Results

Projected incidence of HER2-positive eBC in EU5 increased from 36,966 to 39,039 pts between 2020 -2029. Annual population eligible for adjuvant T-DM1 tx was stable at approximately 10,000 pts over the study time period. Total cases of mBC prevented with adjuvant T-DM1 from 2020 -2029 is projected to increase from 46 to 1732 with a cumulative total of 10,139 or 27% of total projected incident-relapsed mBC cases among pts with HER2-positive, non-pCR eBC. At year 10 (2029), the model projects 3798 pts prevented from developing mBC with T, thus a 46% decrease with TDM-1 relative to T. Findings were similar across EU5. Modeling estimates may not consider shifts in incidence or reflect actual practice or events occurring outside of the study period.

Conclusions

Model outputs show a reduction of mBC due to T-DM1 beyond the maximum impact of T in eBC in EU5, thereby changing the epidemiology of HER2-positive BC over time, illustrating an even further decrease in current clinical and economic burden of this disease in these high-risk pts.

Clinical trial identification

Editorial acknowledgement

Purvi Shah, MD, of Ashfield Healthcare Communications (a UDG Healthcare plc company), supported by F Hoffmann-La Roche Ltd/Genentech, Inc.

Legal entity responsible for the study

F Hoffmann-La Roche Ltd/Genentech, Inc.

Funding

F Hoffmann-La Roche Ltd/Genentech, Inc.

Disclosure

M.Y. Williamson: Shareholder / Stockholder / Stock options, Full / Part-time employment: F. Hoffmann -La Roche Ltd. A. Tomar: Full / Part-time employment: ZS Associates International Inc. G.S. Jhuti: Shareholder / Stockholder / Stock options, Full / Part-time employment: F. Hoffmann -La Roche Ltd. C. Revil: Shareholder / Stockholder / Stock options, Full / Part-time employment: F. Hoffmann -La Roche Ltd. A. Kotzeva: Full / Part-time employment: F. Hoffmann -La Roche Ltd. K. Gururaj: Full / Part-time employment: ZS Associates International Inc.