P-139 Trastuzumab deruxtecan showed similar clinical benefit for frail HER2 positive gastric cancer patients: Retrospective observational study

Abstract

Trastuzumab deruxtecan(T-DXd) showed promising effect for HER2 positive advanced gastric cancer (AGC) patients who previously received two or more chemotherapy in DESTINY-Gastric01 trial. Few HER2-positive AGC patients can receive T-DXd after third-line or later line treatment. In addition, although there are many frail cases in AGC patients receiving third-line treatment, the effectiveness and safety of T-DXd for frail cases is not yet clear. In this multicenter retrospective study, we collected clinical data of HER2 positive AGC patients received T-DXd from Electronic medical record system. Frail is defined as 75 years or older with any PS. 19 AGC patients were received T-DXd after two or more prior chemotherapy. Frail patients were 6 patients (32%). There is no significant difference between frail and non-frail group in patients background. In all patients, response rate (RR) was 42%, disease control rate was 78%, median progression free survival (PFS) was 4 months (95% CI: 2.6-6.5) and median overall survival (OS) was 6.1 months (95%CI:3.7-9.4). There were no significantly difference in RR, DCR, PFS, OS between frail group and non-frail group. There was no significant difference in safety between frail and non-frail patients. However, dose reduction was required at 47% in all population and frail group tended to have more dose reductions (67% vs 38%). In the frail group, 3 cases of dose reduction from the initial administration were observed. No patients in the frail group could receive post therapy after T-DXd failure. T-DXd showed clinical benefit for AGC patients in clinical setting including frail patients. However, dose reduction was necessary in about 50% of all population, and there was a tendency that dose reduction was more often required in frail patients. Further large study including frail patients is needed.