Real-Life Experience of HER2 (Human Epidermal Growth Factor Receptor 2)-Positive Advanced Breast Cancer Patients
Rita Bizarro1, Isabel Pazos2, Alexandra Teixeira3
1Medical Oncology, Beatriz Ângelo Hospital, Loures, PRT.
Background:
Substantial improvements in survival have been observed in HER2 (human epidermal growth factor receptor 2)-positive (HER2+) inoperable or metastatic breast cancer (advanced breast cancer [ABC]) in recent years, driven by the introduction and widespread use of multiple novel agents. The DESTINY-Breast02 trial compared the efficacy and safety of trastuzumab deruxtecan (T-DXd) in patients with HER2+ ABC formerly treated with trastuzumab emtansine (T-DM1), demonstrating significant improvements in both overall survival (OS) and progression-free survival (PFS).
Methods:
We conducted a national, multicentric, retrospective study to describe real-world treatment patterns, PFS, OS, safety, and key toxicities associated with T-DXd use in Portugal, following the DESTINY-Breast02 inclusion criteria.
Results:
A total of 100 women with HER2+ ABC from 17 centers were included, all of whom had received at least two prior treatments for advanced disease and were treated with T-DXd between July 2021 and May 2023. The mean age was 53.9 years n(standard deviation: 9.9). Thirty-six patients presented with synchronous metastatic disease. The most common metastatic site was bone, in 61 (61%) patients; 72 (72%) had visceral metastases, and 21 patients (21%) had brain metastases. The median follow-up was 10 months, with a median of 11 T-DXd cycles administered. Prior treatments included pertuzumab in 71 (71%) patients and T-DM1 in 84 (84%). T-DXd was administered as third-line therapy in 52 (52%) patients, as fourth-line therapy in 15 (15%), and as fifth-line therapy and beyond in 23 (23%) patients. The overall response rate (ORR) was 44%, and the clinical benefit rate (CBR) was 80%. The most frequent toxicities of any grade were nausea in 49 patients (49%), neutropenia in 37 (37%), and alopecia in 34 (34%). Serious adverse events (grade ≥ 3) occurred in 16 (16%) patients, with treatment discontinuation or delays due to adverse events observed in 46 cases (46%). Median OS was not reached, with a 12-month OS rate of 74%. The median PFS was 13 months (95% CI: 10-16 months), and the 12-month PFS rate was 54%.
Conclusions:
This real-world analysis revealed that the efficacy, safety, and tolerability of T-DXd in the Portuguese population are consistent with the outcomes observed in the DESTINY-Breast02 clinical trial.
