Impact of progression sites and line of therapy on survival outcomes in patients with HER-2 positive metastatic breast cancer treated with T-DM1.

OBJECTIVE

Ado-trastuzumab emtansine (T-DM1) is a key treatment for HER2-positive metastatic breast cancer (HER2+ MBC), yet the influence of progression sites and therapy lines on outcomes remains unclear.To assess the relationship between progression sites and the line of T-DM1 therapy with survival outcomes in HER2+ MBC.

METHODS

We retrospectively analyzed 123 patients with HER2+ MBC treated with T-DM1. Data on metastatic progression sites (brain, liver, bone, lung, lymph nodes), line of T-DM1 therapy (2nd-line vs ≥3rd-line), and death status were examined. Due to limited survival time data, mortality was used as the primary outcome. Death rates were compared across subgroups using descriptive statistics.

RESULTS

Brain and lung progression were associated with the highest mortality rates (76.7% and 73.1%, respectively). Liver and bone progression also showed elevated death rates (70.0% and 64.3%). Notably, more patients who used T-DM1 as the second-line therapy had a higher mortality rate at 66.7% compared to those treated with it in the third line or after (45.1%).

CONCLUSION

Progression to brain and lung during T-DM1 treatment correlates with higher mortality. Early-line use of T-DM1 may be linked with worse outcomes, possibly due to more aggressive disease biology. The obtained data could inform the decision-making process when treating patients with HER2+ MBC and predict their prognosis.