LBA55 - Primary analysis of a phase II single-arm trial of trastuzumab deruxtecan (T-DXd) in western patients (Pts) with HER2-positive (HER2+) unresectable or metastatic gastric or gastroesophageal junction (GEJ) cancer who progressed on or after a trastuzumab-containing regimen

Background

Overexpression and/or amplification of HER2 occurs in ∼20% of gastric or GEJ cancers. In DESTINY-Gastric01, the HER2-targeted antibody-drug conjugate T-DXd improved response and overall survival vs physician’s choice irinotecan/paclitaxel in pts from Japan/Korea with locally advanced or metastatic HER2+ gastric/GEJ cancer who progressed on ≥2L therapy including trastuzumab. Here, we report data from the single-arm, phase 2 DESTINY-Gastric02 trial, the first 2L study of T-DXd in Western pts with HER2+ gastric/GEJ cancer.

Methods

Pts with centrally confirmed HER2+ (IHC3+ or IHC2+/ISH+ biopsy after trastuzumab-based therapy) unresectable/metastatic gastric/GEJ cancer who progressed on or after trastuzumab-containing 1L therapy were treated with T-DXd 6.4 mg/kg intravenously every 3 weeks. The primary endpoint was confirmed objective response rate (ORR) per RECIST v1.1 by independent central review (ICR). Progression-free survival (PFS), duration of response (DoR) by ICR, and safety were secondary endpoints.

Results

Between Dec 2019 and Apr 2021, 79 pts from the US/EU with a median 1.0 (range 1-2) prior therapies were treated with T-DXd for a median of 4.3 mo (range 0.7-15.9). Median duration of follow-up was 5.7 mo (range 0.7-15.2). Median age was 61 years (range 20-78). Confirmed ORR, median PFS, median DoR, and treatment emergent adverse events (TEAEs) are shown (Table). The most common TEAEs were nausea (66%), vomiting (42%) and fatigue (41%). Adjudicated drug-related interstitial lung disease occurred in 6 (7.6%) pts (grade 1-2, 5 pts; grade 5, 1 pt). Table: LBA55

T-DXd in pts with HER2+ gastric/GEJ adenocarcinoma

Conclusions

T-DXd demonstrated clinical efficacy and a manageable safety profile in 2L treatment of Western patients with HER2+ unresectable/metastatic gastric/GEJ cancer.

Clinical trial identification

NCT04014075.

Editorial acknowledgement

Under the guidance of authors, assistance in medical writing and editorial support was provided by Sara Duggan, PhD, of ApotheCom and was funded by Daiichi Sankyo, Inc.

Legal entity responsible for the study

Daiichi Sankyo, Inc., and AstraZeneca.

Funding

This study was funded by Daiichi Sankyo, Inc., and AstraZeneca.

Disclosure

E. van Cutsem: Financial Interests, Personal, Advisory Role, Advisory/Consultancy: AbbVie, Array, Astellas, Astrazeneca, Bayer, Beigene, Biocartis, Boehringer Ingelheim, Bristol Myers Squibb, Celgene, Daiichi, Halozyme, GSK, Helsinn, Incyte, Ipsen, Janssen Research, Lilly, Merck Sharp & Dohme, Merck KGaA, Mirati, Novartis, Pierre Fabr; Financial Interests, Institutional, Research Grant: Amgen, Bayer, Boehringer Ingelheim, Bristol Myers Squibb, Celgene, Ipsen, Lilly, Merck Sharp & Dohme, Merck KGaA, Novartis, Roche, Servier. M. Di Bartolomeo: Financial Interests, Institutional, Other, Honoraria: Lilly; Financial Interests, Institutional, Research Grant: Lilly; Financial Interests, Personal, Speaker’s Bureau, Speaker Bureau/Expert Testimony: BMS, MSD, Lilly, Servier, Daiichi . E. Smyth: Financial Interests, Personal, Advisory Role, Advisory/Consultancy: Amal Therapeutics, Astellas, AstraZeneca , Beigene, BMS, Celgene, Five Prime, Merck, Roche, Pfizer, Servier, Zymeworks; Financial Interests, Personal, Leadership Role: EORTC Gastric Cancer Taskforce co-lead; ESMO GI Faculty; Financial Interests, Personal, Other, Travel expenses, including accommodations: Astellas, AstraZeneca , BMS, Celgene, Servier, Zymeworks; Financial Interests, Personal, Research Grant: AstraZeneca , Astellas, Basilea, BMS, Daiichi Sankyo, Roche, Macrogenics, MSD. I. Chau: Financial Interests, Personal, Advisory Role: Eli-Lilly, Bristol Meyers Squibb, MSD, Bayer, Roche, Merck-Serono, Five Prime Therapeutics, AstraZeneca, OncXerna, Pierre Fabre, Boehringer Ingelheim, Incyte, Astellas; Financial Interests, Institutional, Research Grant: Eli-Lilly, Janssen-Cilag; Financial Interests, Personal, Other, Honoraria: Eli-Lilly, Eisai. H. Park: Financial Interests, Institutional, Research Grant: Adlai Nortye USA, Alpine Immune Sciences, Ambrx, Amgen, Aprea Therapeutics AB, Array BioPharma, Bayer, BeiGene, BJ Bioscience, Bristol Myers Squibb, Daiichi Pharmaceutical, Eli Lilly, Elicio Therapeutics, EMD Serono, Exelixis, Genentech, Gilead Sciences,; Non-Financial Interests, Personal, Other, Non-remunerated activity: Jacobio; Jounce. S. Siena: Financial Interests, Personal, Advisory Role: Amgen, AstraZeneca, Bayer, BMS, CheckmAb, Daiichi Sankyo, Merck, and Seattle Genetics. S. Lonardi: Financial Interests, Personal, Advisory Role, Advisory/Consultancy: Amgen, Merck Serono, Lilly, AstraZeneca , Incyte, Daiichi Sankyo, Bristol Myers Squibb, Servier, MSD; Financial Interests, Personal, Speaker’s Bureau, Speaker Bureau/Expert Testimony: Roche, Lilly, Bristol Myers Squibb, Servier, Merck Serono, Pierre-Fabre, GSK, Amgen; Financial Interests, Institutional, Research Grant: Amgen, Merck Serono, Bayer, Roche, Lilly, AstraZeneca , Bristol Myers Squibb. Z.A. Wainberg: Financial Interests, Personal, Advisory Role, Advisory/Consultancy: Merck, Ibsen, Lilly, Five prime, QED, Molecular Templates, Daiichi, AstraZeneca; Other, Personal, Other, Travel expenses, including accommodations: Lilly, Merck, Novartis, Daiichi. J.A. Ajani: Financial Interests, Personal, Other, Honoraria: Daiichi Sankyo; Financial Interests, Institutional, Research Grant: Daiichi Sankyo; Financial Interests, Personal, Other, Travel/Accommodations/Expenses: Daiichi Sankyo. J. Chao: Financial Interests, Personal, Advisory Board: Amgen; Financial Interests, Personal, Advisory Board: Astellas; Financial Interests, Personal, Other, Consulting: AstraZeneca; Financial Interests, Personal, Invited Speaker: Bristol Myers Squibb; Financial Interests, Personal, Advisory Board: Bristol Myers Squibb; Financial Interests, Personal, Advisory Board: Daiichi Sankyo; Financial Interests, Personal, Other, Consulting: Lilly; Financial Interests, Personal, Advisory Board: Macrogenics; Financial Interests, Personal, Invited Speaker: Merck; Financial Interests, Personal, Advisory Board: Merck; Financial Interests, Personal, Other, Consulting: Ono Pharmaceuticals; Financial Interests, Personal, Other, Consulting: Roche; Financial Interests, Personal, Advisory Board: Turning Point Therapeutics; Financial Interests, Institutional, Research Grant: Brooklyn Immunotherapeutics; Financial Interests, Institutional, Research Grant: Merck. J. Seraj: Financial Interests, Personal, Full or part-time Employment: Daiichi Sankyo. Y. Kawaguchi: Financial Interests, Personal, Full or part-time Employment: Daiichi Sankyo, Inc.; Financial Interests, Personal, Stocks/Shares: Daiichi Sankyo, Inc. A. Qin: Financial Interests, Personal, Full or part-time Employment: Daiichi Sankyo Inc. J. Singh: Financial Interests, Personal, Full or part-time Employment: Daiichi Sankyo. G. Meinhardt: Financial Interests, Personal, Full or part-time Employment: Daiichi Sankyo; Financial Interests, Personal, Stocks/Shares: Daiichi Sankyo. G. Ku: Financial Interests, Personal, Advisory Role, Advisory/Consultancy: Apexigen, BMS, Eli Lilly, Merck, Pieris, Zymeworks; Financial Interests, Institutional, Research Grant: Arog, AstraZeneca, BMS, Daiichi Sankyo, Merck, Oncolys, Pieris, Zymeworks.