Daiichi Sankyo & AstraZeneca start Phase 3 Trial of DESTINY-Gastric05 for Gastric Cancer treatment

DESTINY-Gastric05 Phase 3 Trial of ENHERTU® Initiated in Patients with Previously Untreated HER2 Positive Advanced Gastric Cancer

Tokyo and Basking Ridge, NJ – (March 31, 2025) – The first patient has been dosed in the DESTINY-Gastric05 phase 3 trial evaluating ENHERTU® (trastuzumab deruxtecan) in combination with a fluoropyrimidine chemotherapy (5-FU or capecitabine) and Merck’s (known as MSD outside of the US and Canada) anti-PD-1 therapy KEYTRUDA® (pembrolizumab) versus trastuzumab in combination with platinum-based chemotherapy (cisplatin plus 5-FU or oxaliplatin plus capecitabine) and pembrolizumab in previously untreated patients with unresectable, locally advanced or metastatic HER2 positive (IHC 3+ or IHC 2+/ISH+) gastric or gastroesophageal junction (GEJ) cancer with PD-L1 CPS ≥1. An exploratory cohort of patients with PD-L1 CPS <1 will be randomized to either ENHERTU plus fluoropyrimidine or trastuzumab plus platinum-based chemotherapy.

ENHERTU is a specifically engineered HER2 directed DXd antibody drug conjugate (ADC) discovered by Daiichi Sankyo (TSE: 4568) and being jointly developed and commercialized by Daiichi Sankyo and AstraZeneca (LSE/STO/Nasdaq: AZN).

Gastric cancer is associated with a poor prognosis, particularly in advanced stages of the disease where the five-year survival rate is 5% to 10%.1 Current recommended first-line treatment for HER2 positive advanced gastric cancer with PD-L1 CPS ≥1 is trastuzumab in combination with platinum-based chemotherapy (cisplatin plus 5-FU or oxaliplatin plus capecitabine) and pembrolizumab. New treatment strategies are needed to continue to improve survival, including additional HER2 directed treatment options.

“Following the positive overall survival results seen with DESTINY-Gastric04 in the second-line HER2 positive metastatic gastric cancer setting, the DESTINY-Gastric05 trial will explore the role of ENHERTU earlier in the metastatic setting as a first-line treatment,” said Mark Rutstein, MD, Global Head, Oncology Clinical Development, Daiichi Sankyo. “With DESTINY-Gastric05, we are evaluating whether a potential platinum-free chemotherapy regimen of ENHERTU combined with immunotherapy and a fluoropyrimidine chemotherapy can further improve survival in patients with previously untreated HER2 positive metastatic gastric cancer.”

ENHERTU is currently approved in more than 65 countries in the second-line or third-line metastatic setting of HER2 positive gastric cancer based on DESTINY-Gastric01, a randomized phase 2 trial, and DESTINY-Gastric02 and DESTINY-Gastric06, two single-arm phase 2 trials.