Real-world experience with trastuzumab deruxtecan among patients with gastric cancer: 4 month-interim analysis of an all-patient post-marketing surveillance study in Japan.

Abstract

273 Background: Interstitial lung disease (ILD) is an important identified risk in the Japanese risk management plan of trastuzumab deruxtecan (T-DXd). In Japan, all-patient post-marketing surveillance (PMS) is underway to investigate the risk of ILD among patients with gastric cancer treated with T-DXd in a real-world setting. We present an interim analysis of the large-scale all-patient PMS. Methods: This is an observational, multicenter, all-patient PMS (jRCT2001200001) with an observation period of 12 months that enrolled all patients treated with T-DXd for HER2-positive unresectable advanced or recurrent gastric cancer between Sep 2020 and Dec 2021. This interim analysis is based on safety data from the first 4 months of all enrolled patients. All potential ILD (identified based on the pre-specified list of AE terms) reported by physicians were adjudicated by an independent ILD adjudication committee (ILD-AC). The incidence of ILD was calculated from adjudicated drug-related ILD. Results: The interim analysis set included 1074 patients with median age of 70 years (range: 23-100). Of the 1074 patients, 1051 (97.9%) received T-DXd as third-line or later treatment. One hundred and eight patients (10.1%) had an Eastern Cooperative Oncology Group performance status (ECOG PS) 2 or greater, and 32 (3.0%), 3 (0.3%), and 23 (2.1%) patients had severe renal impairment (15≤ creatinine clearance (CL) <30 mL/min), end-stage renal disease (CL <15 mL/min), and ILD/radiation pneumonitis at baseline, respectively (all of which were defined as exclusion criteria in clinical trials of T-DXd). Median initial dose of T-DXd was 6.4 mg/kg (range: 3.1-6.4). Median treatment duration of T-DXd was 4.0 months (range: 0.7-4.0). During the first 4 months from the initial treatment, T-DXd was discontinued in 50.9% (547/1074) of patients. The most common reasons for treatment discontinuation were disease progression (n=390, 71.3%), adverse events other than ILD (n=76, 13.9%), and ILD (n=56, 10.2%). All potential ILD that occurred during the first 4 months were adjudicated by ILD-AC, and the incidence of all grades, grade ≥3, and grade 5 adjudicated drug-related ILD were 5.2% (n=56), 1.5% (n=16) and 0.7% (n=7), respectively. Of the 56 patients with adjudicated drug-related ILD, 54 (96.4%) discontinued T-DXd. The incidence of adjudicated drug-related ILD by time from initial treatment of T-DXd were 0.7% (7/1074) at ≤ 1 month, 2.0% (19/949) at 1-2 months, 2.7% (22/829) at 2-3 months, and 1.2% (8/652) at 3-4 months. Conclusions: The interim analysis revealed patient experiences and treatment profiles of T-DXd and the incidence of ILD during the first 4 months since initial treatment in a real-world setting in Japan. The final analysis including a risk factor analysis for ILD of the ongoing PMS is planned.