Significance of circulating tumor cell monitoring in targeted therapy for gastrointestinal stromal tumors / 中华胃肠外科杂志

ABSTRACT

Objective: To explore the significance of circulating tumor cell (CTC) monitoring in evaluating the efficacy of targeted therapy for gastrointestinal stromal tumor (GIST). Methods: A prospective cohort study was performed. The data of patients with locally advanced GIST or liver metastasis who were admitted to The Affiliated Hospital of Nantong University from August 2013 to December 2018 were collected. Inclusion criteria (1) patients aged older than 18 years; (2) patients who were diagnosed with GIST based on pathology; (3) patients without surgery, whose preoperative imaging evaluation of GIST found the violations of the surrounding organs or partial transfer of an estimated difficulty to achieve R0 resection, or the maximum diameter of the tumor > 10 cm, or the liver metastasis, or the expectation of higher risk of surgical complications; (4) patients who were treated with the imatinib 400 mg/d for the first time; (5) Eastern Cooperative Oncology Group (ECOG) score of 0-2. Exclusion criteria (1) genetic testing revealed a D842V mutation in exon 18 of the PDGFRA gene; (2) alanine aminotransferase and/or aspartate aminotransferase > 2.5 times the normal upper limit; (3) serum total bilirubin >1.5 times of normal upper limit; (4) neutrophil count < 1.5×10(9)/L, or platelet count < 75×10(9)/L, or hemoglobin < 60 g/L; (5) creatinine > normal upper limit; (6) patients had serious cardiovascular and cerebrovascular diseases within 12 months before enrollment; (7) female patients were pregnant or lactating; (8) patients suffered from other serious acute and chronic physical or mental problems, and were not suitable for participating in this study judged by researchers. The patients who could not tolerate treatment regimen, or developed serious adverse reactions and did not follow the medication scheme after enrollment were excluded. Before imatinib treatment and 1-month and 2-month after treatment, quantitative PCR was used to detect the DOG-1 expression of monocytes in peripheral blood, and the ratio of DOG-1/β-actin > 3×10(-5) was used as the CTC positive threshold of GIST. The positive rate of CTC, the efficacy of imatinib treatment (complete response, partial response, stable disease, progressive disease, and occurrence of adverse reactions), and the relationship between CTC positive rate and clinicopathological characteristics of patients were analyzed. Furthermore, the ratio of DOG-1 decrease/baseline DOG-1 after 1-month of treatment was used as an indicator to evaluate whether targeted therapy was effective. The receiver operating characteristic (ROC) curve was rendered, and the area under the curve (AUC) was calculated. Results: A total of 68 GIST patients were enrolled in this study, including 39 cases of locally advanced GIST and 29 cases with liver metastases, 32 males and 36 females with the mean age of (51.2±11.8) (range 31 to 74) years. After 2-month of imatinib treatment, 43 cases were evaluated as partial response, 11 cases as stable disease, and 14 cases as progressive disease, with an effective rate of 79.4% (54/68). During the treatment of imatinib, the incidence of grade 3 or higher adverse reactions was 22.1% (15/68), including 12 cases of grade 3 neutropenia and 3 of grade 4 drug eruption, which were all relieved after conservative treatment. The positive rates of CTC in 68 patients before treatment, 1-month and 2-month after treatment were 66.2% (45/68), 41.2% (28/68) and 23.5% (16/68), respectively. The positive rate of CTC was associated with tumor size, liver metastasis, mitotic count and risk level (all P<0.05). By analyzing the effective group and the ineffective group of targeted therapy, it was found that the positive rate of CTC in the effective group showed a decreasing trend, while the positive rate of CTC in the ineffective group showed an increasing trend. The AUC of predicting the efficacy of targeted therapy for GIST was 0.823 by detecting the change trend of CTC 1-month after treatment (P<0.001). When the DOG-1 content decreased by more than 57.5% 1-month after treatment, it can be used as an indicator to judge the effectiveness of the treatment, whose sensitivity was 72.2% and specificity was 100%. Conclusion: The detection of peripheral blood CTC can evaluate the efficacy of targeted therapy in GIST patients and can provide decision-making basis for further clinical treatment.