Patient Case With HER2+ Gastric Carcinoma

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Bassel El-Rayes, MD: I’m Bassel El-Rayes from the Winship Cancer Institute at Emory University, and it’s my pleasure today to present a case that I’ve been involved in of a 66-year-old man with a 4-month history of decreased appetite and diffused abdominal pain.

Past medical history is significant for diabetes, which is medically controlled. The patient had a colonoscopy at age 55, which was unremarkable, and his physical examination reveals bloating and abdominal pain on deep palpation.

His laboratory work-up showed that he had anemia with a hemoglobin level of 9.5 g/dL and platelets of 104,000 per mm3. Otherwise his labs were within normal range.

An endoscopy revealed a mass in the patient’s stomach, and a biopsy showed a well differentiated papillary adenocarcinoma with invasion into the lamina propria. An EUS [endoscopic ultrasound] revealed an extraluminal surface with hyperechogenic spots. Then, we performed an abdominal CT scan on him that confirmed the presence of the 5.1-cm mass in the antrum of the stomach. The rest of the staging reveals stage IV gastric adenocarcinoma. The patient’s ECOG performance status is 1 and his immunohistochemistry score for HER2 revealed an expression of 3+. Biomarker testing for PD-L1 was 0%, and NTRK was negative. MSI [microsatellite instability] testing by PCR [polymerase chain reaction] revealed that he is MSS [microsatellite stable].

After the work-up, treatment was started with FOLFOX [folinic acid, fluorouracil, oxaliplatin] and trastuzumab. He tolerated the treatment well for 5 cycles. However, imaging unfortunately showed 3 new small pulmonary lesions, so his treatment was changed to docetaxel and ramucirumab. The patient tolerated treatment well for 4 cycles, until he developed neutropenia. Then, the patient was started on trastuzumab deruxtecan, and a repeat HER2/neu expression score was not indicated.

This case represents a typical presentation of gastric cancer. Unfortunately, we still diagnose this disease at an advanced stage. It is uncommon to find early stage gastric cancer; the majority is metastatic. Treatment of these patients is usually reliant on systemic therapy as is presented in this case.

The management of gastric cancer is a multidisciplinary effort because it entails evaluation by surgeons for surgical resection, gastroenterologists for staging, pathologists for histologic diagnosis and molecular testing, and of course, radiation oncologists and medical oncologists. At our institution we tend to present these cases at a tumor board for a multidisciplinary discussion.

Transcript edited for clarity.

Case: A 66-Year Old Male With HER2+ Gastric Cancer

Initial presentation

• A 66-year-old man complains of a 4-month history of decreased appetite and diffuse abdominal pain
• PMH: DM, medically controlled; colonoscopy at age 55 was unremarkable; no personal or family history of cancer
• PE: bloating; abdominal pain on deep palpation; otherwise unremarkable
  

Clinical Workup

• Labs: Hb 9.5 g/dL, plt 104 x 109/L; other lab values WNL
• Endoscopy with biopsy: showed well differentiated papillary adenocarcinoma with invasion into the lamina propria
• EUS: irregular borders on extraluminal surfaces with hyperechogenic spots
• Abdominal/pelvic CT confirmed a 5.1 cm lesion with indistinct margins in the antrum of the stomach
• Stage IV gastric adenocarcinoma; ECOG 1
• IHC score for HER2 expression 3+
• Biomarker testing: PD-L1 0%, NTRK -
• MSI by PCR/MMR by IHC: stable

Treatment

• He was started on FOLFOX + trastuzumab
  • Well tolerated for 5 cycles
  • Imaging showed 3 new small pulmonary lesions
• Treatment changed to docetaxel + ramucirumab
  • Treatment was well tolerated for 4 cycles when he developed neutropenia
• Patient was started on trastuzumab deruxtecan; repeat HER2 expression score was not indicated