AstraZeneca and Daiichi Sankyo Company, Limited's (Daiichi Sankyo) announced the detailed results from the positive registrational, randomized controlled Phase II DESTINY-Gastric01 trial showed ENHERTU® (fam-trastuzumab deruxtecan-nxki) demonstrated a statistically significant and clinically meaningful improvement in objective response rate (ORR) and overall survival (OS), a key secondary endpoint, against chemotherapy. The trial evaluated patients with HER2-positive unresectable or metastatic gastric or gastroesophageal junction adenocarcinoma that had progressed following two or more treatment regimens including trastuzumab and chemotherapy. Gastric cancer is the third leading cause of cancer mortality with a five-year survival rate of 5% for metastatic disease.

Approximately one in five gastric cancers are considered HER2 positive. The confirmed ORR, assessed by independent central review, was 42.9% with ENHERTU monotherapy (6.4mg/kg) compared to 12.5% with investigator's choice of chemotherapy (paclitaxel or irinotecan). Ten complete responses (CRs) and 41 partial responses (PRs) were seen in patients treated with ENHERTU versus no CRs and seven PRs seen in patients treated with chemotherapy.

Patients treated with ENHERTU had a 41% reduction in the risk of death versus patients treated with chemotherapy (based on a hazard ratio [HR] of 0.59; 95% confidence interval [CI] 0.39-0.88; p=0.0097) at a pre-specified interim analysis. The median OS was 12.5 months versus 8.4 months with chemotherapy. The estimated OS rate at one year in the ENHERTU arm was 52.1% and 28.9% with the chemotherapy arm.

The trial evaluated patients with HER2-positive unresectable or metastatic gastric or gastroesophageal junction adenocarcinoma that had progressed following two or more treatment regimens including trastuzumab and chemotherapy. Gastric cancer is the third leading cause of cancer mortality with a five-year survival rate of 5% for metastatic disease. Approximately one in five gastric cancers are considered HER2 positive.

The confirmed ORR, assessed by independent central review, was 42.9% with ENHERTU monotherapy (6.4mg/kg) compared to 12.5% with investigator's choice of chemotherapy (paclitaxel or irinotecan). Ten complete responses (CRs) and 41 partial responses (PRs) were seen in patients treated with ENHERTU versus no CRs and seven PRs seen in patients treated with chemotherapy. Patients treated with ENHERTU had a 41% reduction in the risk of death versus patients treated with chemotherapy (based on a hazard ratio [HR] of 0.59; 95% confidence interval [CI] 0.39-0.88; p=0.0097) at a pre-specified interim analysis.

The median OS was 12.5 months versus 8.4 months with chemotherapy. The estimated OS rate at one year in the ENHERTU arm was 52.1% and 28.9% with the chemotherapy arm.