The FDA on Friday said it has expanded the label for AstraZeneca and Daiichi Sankyo's Enhertu (fam-trastuzumab deruxtecan-nxki) to include adults with locally advanced or metastatic HER2-positive gastric or gastroesophageal (GEJ) adenocarcinoma previously treated with a trastuzumab-based regimen. The antibody-drug conjugate was granted an accelerated approval by the agency in late 2019 to treat unresectable HER2-positive breast cancer in patients who have received at least two prior anti-HER2-based regimens in the metastatic setting.
The latest filing, which was assessed under a priority review, was supported by data from the Phase II DESTINY-Gastric01 trial involving 188 patients with HER2-positive locally advanced or metastatic gastric or GEJ adenocarcinoma who had progressed on at least two prior regimens, including trastuzumab, a fluoropyrimidine- and a platinum-containing chemotherapy.
The confirmed objective response rate (ORR) was significantly higher among Enhertu-treated patients at 40.5% than among those given investigator's choice of chemotherapy, where the ORR was 11.3%. Complete and partial responses rates in the Enhertu group were 7.9% and 32.5%, respectively, compared with corresponding rates of 0% and 11.3% for patients treated with chemotherapy. Median overall survival was 12.5 months in the Enhertu arm versus 8.4 months in the comparator group, while median progression-free survival was 5.6 months and 3.5 months, respectively. The FDA had previously granted Enhertu both breakthrough therapy and orphan drug designations in the gastric cancer indication.
In 2019, AstraZeneca agreed to pay Daiichi Sankyo $1.35 billion upfront as part of a deal potentially worth as much as $6.9 billion to jointly develop and commercialise Enhertu. The companies are co-developing and marketing Enhertu worldwide, except in Japan, where Daiichi Sankyo holds exclusive rights. The drug was cleared in the HER2-positive metastatic gastric cancer indication in Japan last September.
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