Could methylated reprimo cell-free DNA serve as a novel tumor marker to assess response in locally advanced gastric cancer treated with preoperative chemotherapy?

Abstract

101 Background: Gastric cancer (GC) is one of the leading causes of cancer death. Perioperative chemotherapy (CT) for locally advanced GC improves curative resection rates and survival compared to surgery alone. Response assessment is challenging and no tumor markers have been validated for this purpose. We conducted a pilot study to investigate the role of methylated Reprimo (RPRM) cell-free DNA (cfDNA) as tumor marker for assessment of response to preoperative CT in patients enrolled in the study GOCCHI 2009-01 (NCT01633203). Methods: Patients with locally advanced GC referred to receive preoperative CT with Epirubicin + Cisplatin + Capecitabine for 3 cycles were offered to enter the study. Patients had to have operable GC, with baseline CT showing a transmural tumor and/or regional lymphnode metastasis with no distant spread assessed by a multidisciplinary tumor board. After the approval of the amendment of the protocol to allow blood sampling for tumor marker measurement and only if informed consent had been given, blood samples were taken at day one of each cycle of preoperative CT. The status of methylated RPRM cfDNA was assessed by Methylight and the number of copies per mL was determined. Patients with at least 2 samples were analyzed. Results: Thirteen patients signed the informed consent form for this substudy, and 11 patients had blood samples available for analysis. Of these, 8 patients had detectable methylated RPRM cfDNA on Day 1 of the first cycle (i.e. baseline). Five patients showed decrease in methylated RPRM cfDNA, while 5 patients had increased levels of the tumor marker in subsequent measurements. In one patient, methylated RPRM cfDNA was not detected in either of two assessments. One patient with a marked increase in methylated RPRM cfDNA after two cycles of CT had metastatic disease at laparotomy. Correlation between pathological findings and changes in methylated RPRM cfDNA will be presented. Conclusions: Our findings suggest that methylated RPRM cfDNA could serve as a novel tumor marker to assess response in locally advanced GC treated with preoperative chemotherapy. Further validation of these preliminary results is warranted.