Real-World Treatment Patterns of Tucatinib Therapy in HER2-Positive MBC

The oral HER2 inhibitor tucatinib is indicated for use in combination with trastuzumab and capecitabine for patients with previously treated HER2-positive metastatic breast cancer (MBC), based on results of the randomized HER2CLIMB trial, which demonstrated a median overall survival of 21.9 months and progression-free survival (PFS) of 7.8 months. The objective of the current retrospective study was to describe the patient characteristics, treatment patterns, and clinical outcomes for tucatinib-based treatment in the real-world setting. Findings of this trial were presented at the 2023 ASCO annual meeting.

This retrospective study identified patients in the Komodo Health claims database who were diagnosed with MBC (between January 1, 2017, and September 3, 2022) and initiated tucatinib following its approval by the FDA in April 2020. Patient characteristics were described in the baseline period (≥6 months from tucatinib initiation). Key outcomes were time to next treatment (TTNT), time to discontinuation (TTD), and persistence (proportion continuing treatment at each time point) in all tucatinib-treated patients and in patients receiving tucatinib immediately following fam-trastuzumab deruxtecan (T-DXd).

In all, 528 patients with HER2-positive MBC and who received tucatinib-based treatment were identified. Of these, 57 (11%) received tucatinib in the first line, 164 (31%) in the second line (2L), 154 (29%) in the third line (3L), and 153 (29%) in the fourth line or later (4L+). Median follow-up from tucatinib initiation was 9 months. A total of 400 patients (76%) had brain metastasis (BM) prior to initiating tucatinib.

In the overall population, median TTNT was 10.7 months, median TTD was 8.5 months, and tucatinib persistence was 46% at 12 months. In patients receiving 2L or 3L tucatinib, median TTNT was 11.5 months, median TTD was 9.1 months, and tucatinib persistence was 49% at 12 months. In the patients who received tucatinib immediately following T-DXd (n=61; 12%), 12 received tucatinib in 2L/3L, 49 received tucatinib in 4L+, and 36 (59%) had BM prior to initiating tucatinib. In this cohort, TTNT was 7.5 months and TTD was 7.3 months.

Real-world data from this large retrospective analysis suggest that tucatinib-based treatment exhibits durable effectiveness among women with HER2-positive MBC across multiple lines of therapy and in the presence/absence of BM.


Anders CK, Neuberger E, Schwartz NRM, et al. Real-world patient characteristics and treatment patterns associated with tucatinib therapy in patients with HER2+ metastatic breast cancer. Abstract presented at: ASCO Annual Meeting, June 2-6, 2023; Chicago, IL. Abstract 1051.

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