Updated Overall Survival Analysis of ROSET-BM Trial Shows Trastuzumab Deruxtecan Has Promising Effectiveness in HER2+ MBC

The multicenter ROSET-BM (UMIN000044995) study conducted a retrospective chart review to evaluate the efficacy and safety of trastuzumab deruxtecan (T-DXd) treatment in patients with HER2+ metastatic breast cancer (MBC) with brain metastases (BM) and/or leptomeningeal carcinomatosis (LMC). Updated overall survival (OS) analysis was conducted using 1-year follow-up data (data cutoff: October 31, 2022) to confirm the long-term effectiveness of T-DXd in HER2+ MBC patients with BM and/or LMC; these data were presented at the 2023 SABCS Annual Meeting and summarized here.

In this updated OS analysis, the ROSET-BM study included a total of 104 patients who received T-DXd treatment between May 25, 2020, and April 30, 2021. The study population had a median of 4 prior lines of therapy. Median time from first diagnosis of MBC to first administration of T-DXd was 37.5 months. Median time from first diagnosis of BM to first administration of T-DXd was 18.9 months. The majority of patients had HER IHC 3+ expression, active BM (86.5%), 5.8% had stable BM, 1.9% had LMC only, and 5.8% was unclassified (image not evaluated).

At a median duration of follow-up of 20.4 months, the 1-year OS rate in the total cohort was 74.8%, 2-year OS rate was 56.0%; median OS was not reached (NR). Median OS was 27.0 months in the active BM cohort Median progression-free survival (PFS) in the total cohort was 14.6 months. Median time to treatment failure was 9.3 months in the total cohort.

Discontinuation of T-Dxd treatment were reported in 71.2% of patients; of these, 26.9% was due to adverse events. The most common adverse event leading to discontinuation of T-DXd was interstitial lung disease (ILD; 24 patients, 23.1%). Median time to onset of an ILD event was 5.3 months.

Based on updated OS results of this retrospective chart review, the authors concluded that T-DXd has promising effectiveness in patients with HER2+ MBC with long-term and heavily pretreated BM and LMC.

Source:

Yamanaka T, Niikura N, Nakayama T, et al. Trastuzumab deruxtecan for the treatment of patients with HER2-positive breast cancer with brain and/or leptomeningeal metastases: an updated overall survival analysis using data from a multicenter retrospective study (ROSET-BM). Presented at the 46th San Antonio Breast Cancer Symposium Annual Meeting, December 5-9, 2023; San Antonio, TX: Abstract PO2-04-04.