Investigational Gastric Cancer Drug Elicits High Disease Control Rate

Median progression-free survival was 5.8 months among patients with HER2-positive gastric cancer who were treated with DS-8201.

Daiichi Sankyo recently announced new safety and efficacy data for the investigational drug DS-8201 at the 2018 American Society of Clinical Oncology Gastrointestinal Cancers Symposium, according to a press release.

DS-8201 is an experimental human epidermal growth factor receptor 2 (HER2)-targeting antibody drug conjugate that is being investigated in patients with HER2-positive (HER2+) gastric cancer who were previously treated with trastuzumab and chemotherapy.

The updated analysis discusses results from 44 patients with HER2+ gastric cancer or gastroesophageal junction adenocarcinoma. The investigators noted that 17 patients were still on treatment at the time of the analysis.

The researchers found that treatment with DS-8201 resulted in a confirmed overall response rate of 45.5% and a disease control rate of 81.8% in these patients, according to the release.

Additionally, the median progression-free survival was 5.8 months among patients treated with DS-8201.

"Gastric cancer can be difficult to treat due to its molecular complexity, and currently there are no HER2-targeted therapies or antibody drug conjugates approved for HER2+ advanced gastric cancer that progresses following treatment with trastuzumab," said Toshihiko Doi, MD, PhD. "These phase 1 results are encouraging and demonstrate the importance of continuing to study the potential of DS-8201 in treating HER2-positive gastric cancer. The pivotal phase 2 study is currently underway."

A separate analysis of 23 patients previously treated with irinotecan demonstrated that DS-8201 resulted in a confirmed overall response rate of 43.5% and a disease control rate of 82.6%, according to the release.

The median duration of response was 6.9 months and the progression-free survival was 4.1 months for this group of patients, according to the release.

"These data from patients with HER2+ gastric cancer who have failed HER2-targeted therapy combined with chemotherapy, and for many who also failed irinotecan as a systemic chemotherapy suggest that the ADC technology of DS-8201 appears able to deliver on what it was specifically researched and innovated for: a smart chemotherapy approach to tumors expressing some degree of HER2 receptors, regardless of prior treatment with a topoisomerase I inhibitor," said Antoine Yver, MD, MSc, executive vice president and global head, Oncology Research and Development, Daiichi Sankyo.

Updated safety data were also presented for trastuzumab-treated patients. Common adverse events included nausea, decreased appetite, platelet count decrease, white blood cell decrease, and constipation.

Based on these findings, patients are being enrolled in the phase 2 DESTINY-Gastric01 clinical trial, according to the release.

"A comprehensive translational research effort is planned and underway to further understand the biological basis for the observed activity, including the role of tumor heterogeneity and HER2 expression, the mechanisms of resistance that may have contributed to failing prior lines of treatment, and factors more directly related to the unique pharmacological profile of DS-8201,” Dr Yver said.