The worldwide impact of HER2-targeted treatments in women with breast cancer: An epidemiological modeling study.

Abstract

543 Background: HER2-targeted therapies (trastuzumab, pertuzumab, and T-DM1) have revolutionized the treatment and epidemiological landscape of HER2+ breast cancer, resulting in population-level increases in survival and decreases in disease recurrence. The aim of this epidemiological modeling study was to quantify the estimated global impact of HER2-targeted therapies, by estimating the number of women diagnosed with HER2+ early breast cancer (eBC) who have avoided (or will avoid) metastatic disease recurrence following treatment. Methods: We used data and projections from cancer registries, observational studies, clinical trials, and drug sales volumes (ie, utilization) to create annual country-level synthetic cohorts of patients diagnosed with HER2+ eBC, for the years 2004-2033 in 185 countries. The real-world uptake of HER2-targeted treatments and treatment flow was estimated in the main scenario. The impact of chemotherapy alone was estimated in the counterfactual scenario, assuming 100% chemotherapy worldwide. The occurrence of distant recurrences was modeled in both scenarios using weighted transitional probability averages based on invasive disease-free survival curves from clinical trials. Results: In total, during the 3-decade study period, we predicted that 11.9 million (M) women would be diagnosed with HER2+ eBC, out of which 7.5M were estimated to be treated with HER2-targeted therapies in a real-world uptake scenario. In the counterfactual scenario with only chemotherapy available, a total of 2.9M women were estimated to experience a metastatic disease recurrence, compared to only 2.1M women in the base scenario of predicted real-world uptake of HER2+ targeted therapies. This corresponds to a reduction of 26% or 768,000 women who may avoid metastatic recurrence since the introduction of HER2-targeted therapies (Table). Conclusions: HER2+ targeted therapies have substantially improved breast cancer outcomes and continue to contribute to the reduction in breast cancer recurrence rates. Further research may elucidate treatment-related reductions in costs to society as a result of population-level improvements in disease outcomes for breast cancer survivors. Given the expected rise in the burden of breast cancer globally, therapeutic advances and increased treatment utilization may further accelerate global patient benefit. [Table: see text]