ctDNA Screening in Advanced HER2 Positive Gastric Cancer
ctDNA Screening in Advanced HER2 Positive Gastric Cancer
To identify molecular biomarker panel correlating with efficacy of trastuzuamb in advanced
 HER2 positive gastric cancer patients. To observe the molecular evolution of HER2 positive
 gastric cancer during treatment by ctDNA detection.
Molecular events including gene mutation, fusion and amplification will be detected by next
 generation sequencing platform (OncoScreen Plus panelTM) using ctDNA collected from
 peripheral blood samples of gastric cancer patients. For HER2 positive patients, samples will
 be collected at baseline, first surveillance after treatment and disease progression. For
 HER2 negative patients, samples will be collected at baseline as negative control.
Inclusion Criteria:

 1. Male/female patients aged over 18 years.

 2. Histologically confirmed gastric adenocarcinoma. Gastric tumors should be treatment
 naïve unresectable or metastatic disease, or recurrence over 6 months after finish of
 adjuvant chemotherapy.

 3. HER2 status is confirmed by IHC/FISH. HER2 positive: IHC 3+ or IHC 2+ plus FISH
 positive, HER2 negative: IHC 0/1+ or IHC 2+ plus FISH negative.

 4. At least one measurable lesion should be confirmed by imaging examination.

 5. Eligible peripheral blood samples

 6. Patients with enough organ function and performance status (ECOG 0-2) can tolerant
 chemotherapy.

 7. For HER2 positive patients, trastuzumab should be used as first-line treatment. The
 regimen of chemotherapy should be platinum plus oral fluorouracil.

 8. For HER2 negative patients, clinicopathological characteristics should be matched to
 HER2 positive patients.

 9. Willing to provide clinicopathological information and imaging information.

 Exclusion Criteria:

 1. Patients received systemic treatment before enrolled or finished adjuvant chemotherapy
 less than 6 months.

 2. With second primary malignant diseases.

 3. Other situations assessed by investigator can disturb quality control of the
 investigation.