Trastuzumab deruxtecan (T-DXd) in patients (pts) with HER2-expressing biliary tract cancer (BTC) and pancreatic cancer (PC): Outcomes from DESTINY-PanTumor02 (DP-02).

Abstract

Background: Existing late-line treatment (Tx) options for BTC and PC offer limited long-term benefit. In DP-02, T-DXd showed tumor-agnostic potential, with an objective response rate (ORR) of 37.1% (95% CI 31.3, 43.2) and clinically meaningful survival outcomes in 267 pts with HER2-expressing tumors. Here we report subgroup analyses in the BTC and PC cohorts and characterize pts with an objective response (OR). Methods: This open-label Phase 2 study (NCT04482309) evaluated T-DXd (5.4 mg/kg Q3W) in pts with HER2-expressing (immunohistochemistry [IHC] 3+/2+ by local or central testing) locally advanced/metastatic disease after ≥1 systemic Tx, or without Tx options. The primary endpoint was confirmed ORR by investigator (INV). Secondary endpoints included progression-free survival (PFS) and safety. Exploratory endpoints included efficacy outcomes by HER2 expression. Results: At data cutoff (June 2023), 41 pts with BTC and 25 pts with PC had received T-DXd (median [m] follow up [range]: 6.01 [0.7–29.1] and 4.99 [1.1–27.2] months [mo], respectively); 27 (65.9%) and 18 (72.0%) pts had ≥2 prior Tx regimens, 7 (17.1%) and 2 (8.0%) pts had prior anti-HER2 Tx, and 8 (19.5%) and 18 (72.0%) pts had prior topoisomerase 1 inhibitor Tx, respectively. In pts with BTC and IHC 3+ expression, 9 pts (56.3%; 95% CI 29.9, 80.2; primary tumor locations: n=2 ampulla of Vater; n=2 extrahepatic; n=4 gallbladder; n=1 intrahepatic) had confirmed OR by INV; of these pts, 6 had received ≥2 prior Tx regimens and 4 had PD-L1 immune cell status ≥1%. The Table shows efficacy outcomes in all pts and by central HER2 expression. In pts with BTC and PC, Grade (G) ≥3 drug-related adverse events occurred in 16/41 (39.0%) and 7/25 (28.0%) pts, respectively; adjudicated drug-related interstitial lung disease / pneumonitis occurred in 7/41 (17.1%; n=5 G2; n=1 G3; n=1 G5) and 1/25 (4.0%; n=1 G1) pts, respectively. Conclusions: T-DXd showed clinically meaningful benefit in pts with BTC across primary tumor locations. Low pt numbers limit interpretation of the PC cohort; however, data support further exploration of T-DXd in this population. Safety was consistent with the known profile. These data support T-DXd as a potential Tx for pts with HER2-expressing BTC. Clinical trial information: NCT04482309.