Real-world treatment patterns and clinical outcomes with tucatinib-based therapy in patients with HER2-positive metastatic breast cancer: analyses of two nationwide administrative health claims databases

Purpose To describe real-world characteristics and clinical outcomes among patients with HER2+ MBC receiving tucatinib-based treatments. Methods This retrospective study included patients diagnosed with HER2+ MBC between January 2017 and December 2022 from two administrative health claims databases, Merative TM MarketScan ® and the Komodo Healthcare Map ™ . Patient characteristics were captured at baseline (≤ 6 months prior to tucatinib initiation). Outcomes were assessed starting from tucatinib-based treatment initiation and included real-world time to discontinuation (rwTTD) and treatment persistence. Results There were 150 patients in MarketScan ® who received tucatinib-based therapy: median (IQR) prior lines of therapy (LOT) was 2 (2–4) and 110 patients (73.3%) had brain metastases. 436 patients in Komodo ™ received tucatinib-based therapy: median (IQR) prior LOTs were 2 (1–3), and 307 (70.4%) had brain metastases. Median (95% CI) rwTTD was 7.4 (5.0–13.1) months in MarketScan ® (median follow-up 9.7 months) and 9.0 (7.4–9.8) months in Komodo ™ (median follow-up 10.3 months). In patients who received tucatinib in combination with trastuzumab and capecitabine immediately following trastuzumab deruxtecan (T-DXd) and after ≥ 2 prior HER2-directed therapies (MarketScan ® : n = 26, median prior LOT 4; Komodo: n = 34, median prior LOT 3), median (95% CI) rwTTD was 5.5 (3.4–not reached [NR]) months in MarketScan ® and 4.8 (3.2–NR) months in Komodo. Conclusion These results reinforce the real-world effectiveness of tucatinib in patients with HER2+ MBC, including patients with prior T-DXd treatment. Further research is needed to determine the optimal treatment sequencing for patients with HER2+ MBC.