The oral HER2 inhibitor tucatinib is approved, in combination with trastuzumab and capecitabine, for the treatment of previously treated HER2-positive metastatic breast cancer, based on the results of the randomized HER2CLIMB trial, which demonstrated a median overall survival of 21.9 months and progression-free survival of 7.8 months. The objective of the study was to describe the patient characteristics, treatment patterns, and clinical outcomes for tucatinib-based treatment in the real-world setting. The 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 metastatic breast cancer between January 1, 2017, and September 3, 2022, and initiated tucatinib treatment after its FDA approval in April 2020. The patient characteristics were described in the baseline period (≥6 months from tucatinib initiation). The key outcomes were the time to next treatment (TTNT), time to discontinuation (TTD), and persistence (proportion continuing treatment at each time point) in all patients who received tucatinib and in patients receiving tucatinib immediately after receiving fam-trastuzumab deruxtecan (T-DXd).
In all, 528 patients with HER2-positive metastatic breast cancer who received tucatinib-based treatment were identified. Of these, 57 (11%) received tucatinib as first-line treatment, 164 (31%) as second-line, 154 (29%) third-line, and 153 (29%) as fourth-line or later treatment. The median follow-up from the initiation of tucatinib was 9 months. A total of 400 patients (76%) had brain metastasis before initiating treatment with tucatinib.
In the overall population, the median TTNT was 10.7 months, the median TTD was 8.5 months, and tucatinib persistence was 46% (91/200) at 12 months. In patients receiving second- or third-line tucatinib, the median TTNT was 11.5 months, the median TTD was 9.1 months, and tucatinib persistence was 49% at 12 months. In the patients who received tucatinib immediately after T-DXd (n=61; 12%), 12 received tucatinib as second- or third-line treatment, 49 received tucatinib as fourth-line or later treatment, and 36 (59%) had brain metastasis before initiating treatment with tucatinib. In this cohort, the TTNT was 7.5 months and the 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 metastatic breast cancer across multiple lines of therapy and in the presence and absence of brain metastasis.
Source: 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.