Background: On the basis of phase 2 studies, trastuzumab deruxtecan was approved for patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic gastric cancer or gastroesophageal junction adenocarcinoma who had previously received trastuzumab-based therapy. Ramucirumab plus paclitaxel is also a standard second-line treatment option regardless of HER2 status.
Methods: We conducted an international, randomized, phase 3 trial comparing second-line trastuzumab deruxtecan at a dose of 6.4 mg per kilogram of body weight with ramucirumab plus paclitaxel in patients with HER2-positive metastatic gastric cancer or gastroesophageal junction adenocarcinoma confirmed on tumor biopsy conducted after the patient had progression while receiving trastuzumab-based therapy. The primary end point was overall survival. Secondary end points included progression-free survival, confirmed objective response (complete or partial response lasting ≥4 weeks), disease control, duration of response, and safety.
Results: Among 494 patients who had undergone randomization, overall survival was significantly longer with trastuzumab deruxtecan than with ramucirumab plus paclitaxel (median, 14.7 vs. 11.4 months; hazard ratio for death, 0.70; 95% confidence interval, 0.55 to 0.90; P = 0.004). Significant results were also seen with regard to progression-free survival (hazard ratio for disease progression or death, 0.74; 95% CI, 0.59 to 0.92) and confirmed objective response (in 44.3% of the patients in the trastuzumab deruxtecan group vs. 29.1% of those in the ramucirumab-paclitaxel group). The incidence of drug-related adverse events of any grade was 93.0% with trastuzumab deruxtecan and 91.4% with ramucirumab plus paclitaxel; the incidence of drug-related adverse events of grade 3 or higher was 50.0% and 54.1%, respectively. Adjudicated drug-related interstitial lung disease or pneumonitis occurred in 13.9% of the patients who received trastuzumab deruxtecan (grade 1 or 2 in 33 patients and grade 3 in 1) and in 1.3% of those who received ramucirumab plus paclitaxel (grade 3 in 2 patients and grade 5 in 1).
Conclusions: Trastuzumab deruxtecan led to significantly longer overall survival than ramucirumab plus paclitaxel among patients with HER2-positive metastatic gastric cancer or gastroesophageal junction adenocarcinoma. Adverse events were common in both groups. Events of interstitial lung disease or pneumonitis with trastuzumab deruxtecan, a known risk, were mainly low-grade. (Funded by Daiichi Sankyo and AstraZeneca; DESTINY-Gastric04 ClinicalTrials.gov number, NCT04704934.).
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