Ultrasound-detected gastric changes related to zolbetuximab-induced emesis: a case series

Kazuaki Harada^1*Koichi Ishida²Shiho Kaneko²Tatsuya Yokoyama²Shintaro Sawaguchi²Takeaki Nakamura²Yasuyuki Kawamoyo²Satoshi Yuki²Nishida Mutsumi³Naoya Sakamoto²Yoshito Komatsu¹

• ¹Division of Cancer Center, Hokkaido University Hospital, Sapporo, Japan
• ²Department of Gastroenterology and Hepatology, Hokkaido University Hospital, Sapporo, Japan
• ³Department of Management Strategy, Hokkaido University Hospital, Sapporo, Japan

Background: Zolbetuximab prolongs survival in patients with claudin18.2 (CLDN18.2)-positive gastric cancer (GC) and gastroesophageal junction cancer. However, it is associated with an increased risk of emesis, and its underlying mechanism remains unclear. Case Presentation: This report presents three cases of advanced GC that underwent abdominal ultrasonography (US) during zolbetuximab administration. In two patients with primary gastric lesions, severe nausea occurred during the first treatment cycle. US findings revealed increased echogenicity of the submucosal layer, enhanced layer stratification, and increased blood flow signals, which improved as the emesis subsided. During the second cycle, emesis was milder, and US findings revealed only slight changes. In the third patient who underwent total gastrectomy, no nausea or abnormal US findings were observed. Conclusion: These US findings indicate gastric tumor tissue injury due to zolbetuximab, which is associated with emesis. US is a valuable tool for further elucidating the mechanisms underlying zolbetuximab-induced emesis and may also contribute to the prediction and prevention of this adverse event.