Post-Trastuzumab Deruxtecan Outcomes in Metastatic Breast Cancer

In this study, the researchers investigated the outcomes of different treatment regimens for patients with metastatic breast cancer (MBC) after they had received a drug called trastuzumab deruxtecan (T-DXd). T-DXd is commonly used for treating certain types of breast cancer, but there was limited information on what treatments work best after T-DXd. The researchers aimed to understand how various treatments performed across different types of MBC.

This research is significant because it addresses a gap in knowledge about the best treatment options following T-DXd, a drug used by many patients with MBC. Understanding the effectiveness of subsequent treatments can help doctors make better-informed decisions, potentially improving patient outcomes. This is particularly important as ineffective treatments can lead to faster disease progression and unnecessary side effects.

The researchers conducted a retrospective study using data from a large electronic health record database in the United States. They reviewed information from 793 patients with MBC who started T-DXd between December 2019 and September 2023 and received another line of treatment afterward. The study analyzed how long patients lived without their cancer worsening (progression-free survival) and their overall survival, using statistical methods to compare different treatment regimens.

The study found that the effectiveness of treatments after T-DXd varied by the type of MBC and the specific treatment used. For HER2-positive MBC, patients had a median progression-free survival of 4.6 months, while those with hormone receptor-positive/HER2-negative MBC had 3.4 months, and triple-negative MBC had 2.8 months. Sacituzumab govitecan (SG), another drug, was associated with shorter progression-free survival across all cancer types, indicating possible resistance when used after T-DXd.

These findings suggest that the choice of treatment after T-DXd should be carefully considered, as some options may lead to better outcomes than others. The results highlight the potential need for developing treatments with different mechanisms to overcome resistance seen with certain drug sequences. This information can guide clinicians in selecting more effective treatment strategies for patients with MBC.

The authors suggest further research to explore new treatment options that can effectively follow T-DXd. They also recommend investigating different drug combinations and sequences to identify the most beneficial approaches for patients with T-DXd-refractory disease.

This research was supported by the Terri Brodeur Breast Cancer Foundation, a METAvivor Early Career Investigator Award, and a Saverin Award, all awarded to Paolo Tarantino. Yale University also provided funding and support for this research.