P0453 - Durable Response to Trastuzumab Monotherapy in a Patient With Stage Four Esophageal Adenocarcinoma

Zohaib Ijaz, MD¹, Ilyas Sahin, MD¹, Zara Ijaz, BS², PranayRaj Kondapally, MD^3
1University of Florida Shands, Gainesville, FL; ²University of South Alabama College of Medicine, Mobile, AL; ³University of Alabama In Huntsville, Huntsville, AL

Introduction: Esophageal cancer (EC) presents itself as the seventh most common cancer in the world. EC has a high morbidity and ranks sixth in cancer mortality with a five-year survival rate of less than 21%. The United States has noted an increased incidence in Esophageal Adenocarcinoma (EAC). EAC has a high likelihood of early onset metastasis contributing to a low one-year survival rate of approximately 20%. Standard treatment of stage four disease involves chemotherapy consisting of a platinum base in combination with fluorouracil or oral capecitabine. HER2 is overexpressed in approximately 10-30% of EAC with studies identifying a direct correlation in amplification more proximal to the gastroesophageal junction. Nearly fifteen years ago blockade of HER2 with Herceptin in metastatic EAC was investigated yielding favorable results in overall survival rates with EAC treatment revised to include chemotherapy in combination with Herceptin demonstrated by the ToGA trial. In the group receiving trastuzumab plus chemotherapy, the median overall survival was 13.8 months, whereas in the group receiving chemotherapy alone, the median overall survival was 11.1 months. In metastatic EAC, the utility of trastuzumab as a single agent in the 1st line setting beyond combination therapy is not adequately investigated.

Case Description/Methods: The presented case involves a patient diagnosed with stage IV EAC, HER2-positive but declined chemotherapy. Thus, the patient was offered single agent trastuzumab therapy. To our knowledge, this is the first documented case of a stage IV HER2-positive EAC patient demonstrating a durable response to trastuzumab monotherapy as a first-line therapy for approximately one year.

Discussion: This case suggests that for stage IV EAC patients with HER2 positivity who are not suitable candidates for or decline chemotherapy, single-agent trastuzumab with HER2-targeted therapy may offer a potential clinical response.


Disclosures:


Zohaib Ijaz, MD¹, Ilyas Sahin, MD¹, Zara Ijaz, BS², PranayRaj Kondapally, MD³. P0453 - Durable Response to Trastuzumab Monotherapy in a Patient With Stage Four Esophageal Adenocarcinoma, ACG 2023 Annual Scientific Meeting Abstracts. Vancouver, BC, Canada: American College of Gastroenterology.