195P - Real-life experience of trastuzumab deruxtecan (T-DXd) in patients with HER2-positive advanced breast cancer: A multicentric Portuguese study

Background

Substantial improvement in survival has been seen in HER2+ advanced breast cancer (ABC) over the past years with the introduction and widespread use of multiple novel agents. The DESTINY-Breast02 trial compared the efficacy and safety of T-DXd versus physician’s choice therapy in HER2+ unresectable and/or metastatic breast cancer previously treated with trastuzumab emtansine (T-DM1). It showed a significant improvement in overall survival (OS) and progression-free survival (PFS).

Methods

We conducted a national, multicentric, retrospective study describing real-world treatment patterns and related PFS, OS, treatment safety and main toxicities of T-DXd in Portugal, as per DESTINY-Breast02 criteria. IBM SPSS Statistics 28.0.1 was used for analyzing procedures.

Results

One hundred women, from 17 different centers, with HER2+ ABC who had received at least 2 previous treatments for advanced disease and received T-DXd were included from July 2021 to May 2023. The median age were 53 years old. A total of 32 patients (pts) (34, 8%) had metastatic disease at the time of the diagnosis. The most common metastatic sites were bone (61%), visceral disease (72%) and brain (21%). The median follow-up was 10 months with 11 median cycles administered. The majority, 77, 2%, had received pertuzumab and 91, 7% T-DM1 previously. T-DXd was administered in a second-line setting in 52% and 3^rd line setting in 15% (range 1-7 lines). The objective response rate (ORR) was 44% and the clinical benefit rate (CBR) was 80%. The most frequent toxicities of any grade were emesis (49%), neutropenia (37%), alopecia (34%), pneumonitis (12%) and reduced ejection fraction (5%). Serious adverse events (AEs) (CTCAE ≥ grade 3) were observed in 16 pts (16%). Discontinuation or delay of T-DXd treatment because of AEs occurred in 46% of pts. Median OS was not reached. OS rate at 12 months (m) was 74%. Median PFS was 13 m (95% CI, 10-16 m). PFS rate at 12 m was 53, 7%.

Conclusions

In this analysis we found similarities between clinical trial efficacy and real-world effectiveness as well as safety, tolerability and adverse events in the Portuguese population treated with T-DXd after at least 2 previous lines for HER2+ ABC.

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.