Trastuzumab deruxtecan (T-DXd) in patients (pts) with HER2-expressing head and neck tumors: Outcomes from DESTINY-PanTumor02 (DP-02).

Abstract

6037 Background: In DP-02, T-DXd demonstrated an objective response rate (ORR) by investigator (INV) of 37.1% (95% CI 31.3, 43.2) and clinically meaningful survival outcomes in 267 pretreated pts with HER2-expressing tumors. In this post-hoc analysis, we report outcomes and characterize those with an objective response (OR) in a subset of pts with head and neck cancers (previously included in the ‘other tumor’ cohort), most of which were salivary gland tumors. 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 treatment or without treatment options. The primary endpoint was confirmed ORR by INV. Secondary endpoints included duration of response (DOR), progression-free survival (PFS), disease control rate (DCR), and safety. Exploratory endpoints included efficacy outcomes by HER2 expression. Results: At data cutoff (June 2023), 24 pts with head and neck tumors (n=19 salivary gland, n=3 squamous cell carcinoma [SCC], n=1 adenoid cystic carcinoma, n=1 lacrimal gland) had received treatment (median [m] follow up: 20.8 months [range: 4.7–31.6]). Of these pts, 15 (62.5%) had received ≥2 prior treatment regimens. 10/24 pts (41.7%; 95% CI 22.1, 63.4; n=8 salivary gland, n=1 SCC, n=1 lacrimal gland) had a confirmed OR by INV; 9 responders had received prior radiation therapy, and 4 had known PD-L1 immune cell status ≥1%. The Table shows efficacy outcomes in all pts and by HER2 expression (central testing). Grade (G) ≥3 drug-related adverse events occurred in 10/24 (41.7%) pts. Adjudicated drug-related interstitial lung disease / pneumonitis occurred in 3/24 (12.5%) pts (n=1 G1; n=1 G2; n=1 G5). Conclusions: T-DXd showed clinically meaningful benefit in pretreated pts with head and neck tumors. Responses were observed across HER2 expression levels. Safety was consistent with the known profile. These data support T-DXd as a potential treatment for pretreated pts with HER2-expressing head and neck tumors. Clinical trial information: NCT04482309 . [Table: see text]