by Thibaut
Sanglier, Jinjoo Shim, Neil Lamarre, Claudia Peña-Murillo, Vincent Antao,
Filippo Montemurro
The Breast: Published: January 15, 2023
Background
Trastuzumab
emtansine (T-DM1) has demonstrated improvements in survival and neurological
symptoms in patients with breast cancer with brain metastases (BCBM). This
real-world study investigated the effectiveness of T-DM1 versus lapatinib plus
capecitabine (LC) in patients with BCBM.
Methods
This retrospective,
observational study evaluated patients with HER2–positive BCBM using a
real-world database. Eligible patients had initiated T-DM1 or LC with a prior
diagnosis of brain metastasis and ≥1 prior metastatic breast cancer treatment.
The primary endpoint was overall survival (OS); secondary endpoints were time
to next relevant treatment or death (TTNT) and real-world progression-free
survival (rwPFS). An inverse probability of treatment weighting (IPTW) approach
was used to account for differences in potential baseline characteristics
between treatment groups. Outcomes were described using the Kaplan-Meier
method, and the average treatment effect of initiating T-DM1 versus LC was
estimated using weighted Cox proportional hazard models and hazard ratio (HR).
Results
A total of 214
patients were available for analysis (T-DM1, n = 161; LC,
n = 53). Demographics and baseline characteristics were generally
well-balanced between treatment groups after weighting. After weighting, median
OS was 17.7 (T-DM1) versus 9.6 (LC) months (HR, 0.55 [95% CI, 0.34–0.89]; P=0.013).
Median TTNT was 9.0 (T-DM1) versus 6.0 (LC) months (HR, 0.55 [95% CI,
0.36–0.85]; P = 0.005). After weighting, median rwPFS was 6.0
(T-DM1) versus 4.0 (LC) months (HR, 0.50 [95% CI, 0.36–0.69]; P < 0.001).
Conclusions
These results
support the superior effectiveness and clinical relevance of T-DM1 versus LC in
patients with HER2-positive BCBM in the real world.
