PCN38 - Long-Term Epidemiological Impact of Pertuzumab+Trastuzmab on Metastatic Breast Cancer Incidence in Canada

Abstract

To estimate the impact of pertuzumab+trastuzumab (PH) on avoided relapsed metastatic breast cancer (mBC) cases in the Canadian HER2+ early breast cancer (eBC) population. An epidemiology model was developed to assess the reduction in incident HER2+ mBC cases as a result of HER2+ eBC treatment with PH in Canada. Age-specific BC incidence rates from the Canadian Cancer Registry and the Canadian Cancer Society were applied to population estimates and projections for Canada to determine BC incidence estimates over time. Staging distribution and HER2 and hormone receptor (HR) status data were taken from publicly available databases and published literature sources. Adjuvant treatment rates and disease-free survival (DFS) curves of H regimens and PH were applied to quantify the projected decline in the number of HER2+ eBC patients relapsing to mBC over a 10-year period post-H launch as well as the additional decline 10 years post-PH launch. DFS estimates for H were derived from the BCIRG-006 and NSABP studies with incremental benefit of PH over H based on the APHINITY study. Model outputs for HER2+ eBC node positive (N+) and HER2+ eBC HR-negative (HR-) subgroups were provided. Among HER2+ eBC N+ patients, assuming 100% peak treatment uptake of PH, the number of mBC cases projected to be prevented in this Canadian population is 372 over 10 years or a 9.2% reduction. For HER2+ eBC HR-, assuming peak PH treatment uptake of 100%, the number of mBC cases projected to be prevented in this population is 262 over 10 years or a 9.7% reduction. Progression from eBC to mBC can incur a substantial economic and societal burden. Early treatment with PH can lead to further reductions in HER2+ mBC incidence over the long-term and may translate into significant cost savings in Canada.