KRAS mutant circulating free DNA (cfDNA) in peripheral blood as a biomarker in patients diagnosed with pancreatic ductal adenocarcinoma

e14524 Background: Humoral tumor markers are used clinically for real-time assessment of therapeutic efficacy. In pancreatic ductal adenocarcinoma (PDAC) the predominant marker is CA19-9, which is not expressed by 10 to 30% of patients depending on race. We compared plasma cell-free DNA (cfDNA) copy number based assay with changes in serum CA19-9 levels and radiological responses to predict responses to systemic therapy. Methods: In a laboratory blinded, prospective multicenter pilot study, 40 non-resectable PDAC patients, treated with (m)FOLFIRINOX, CAPIRI, or gemcitabine +/- nab-paclitaxel) are currently enrolled. CA19-9 was determined in the local center’s laboratory. Tumor cfDNA was measured with a copy-number instability (CNI) scoring assay, determined by next generation sequencing in a centralized laboratory. The CNI score assesses the amount of cfDNA with somatic macro-alterations originating from malignant neoplasms. The difference of the values before commencing therapy (baseline) and prior to cycle 2 (either rising or falling) was calculated as a predictor of standardized radiological evaluation of chemotherapeutic efficacy. Results: 37 patients (3 drop-outs) had data for baseline and cycle 2, of which CA19-9 was elevated and evaluable in 29 patients. The direction from baseline to cycle 2 of CA19-9 and CNI scores were in agreement in 18/29 patients. 9 of 11 cases with discordant CNI score and CA19-9 had treatment response data, and CNI correlated with 7/9 (78%); in contrast 7/9 had rising CA19-9, when response was stable disease or better (22% concordance). In the 27 patients with available imaging, CNI predicted better (n = 18) than CA19-9 (n = 10) (p = 0.03 Fisher’s exact). Conclusions: This comparative study on cfDNA versus CA19-9 suggest that cfDNA CNI quantitation is a potentially more reliable blood based marker for early real-time assessment of efficacy in systemic PDAC therapy than CA19-9, compared to standard of care imaging. The better prediction after the first cycle might be due to the very short in vivo half-life of cfDNA ( < 1hr) compared to about one week for CA19-9. These results justify a larger prospective validation trial.

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Application of Circulating Tumor Cells and Circulating Free DNA from Peripheral Blood in the Prognosis of Advanced Gastric Cancer

Journal of Oncology ◽

10.1155/2022/9635218 ◽

2022 ◽

Vol 2022 ◽

pp. 1-9

Author(s):

Pengjie Yu ◽

Shengmao Zhu ◽

Yushuang Luo ◽

Ganggang Li ◽

Yongqiang Pu ◽

...

Keyword(s):

Gastric Cancer ◽

Neoadjuvant Chemotherapy ◽

Neoadjuvant Therapy ◽

Advanced Gastric Cancer ◽

Tumor Cells ◽

Circulating Tumor Cells ◽

Peripheral Blood ◽

Circulating Free Dna ◽

Free Dna ◽

N Stage

Objective. To explore the application value of circulating tumor cells (CTCs) and circulating free DNA (cfDNA) from peripheral blood in the prognosis of advanced gastric cancer (AGC). Here, we measured CTCs and cfDNA quantity for predicting the outcome of patients. Patients and Methods. Forty-five patients with advanced gastric cancer who underwent neoadjuvant chemotherapy and surgical treatment were enrolled in this study. All patients received neoadjuvant chemotherapy with paclitaxel + S-1 + oxaliplatin (PSOX) regimen, and CTCs and cfDNA of the peripheral blood were detected before and after neoadjuvant therapy. Relationships between the number/type of CTC or cfDNA and the efficacy of neoadjuvant chemotherapy were analyzed. Results. Among 45 patients, 43 (95.6%) were positive, and the positive rate of mesenchymal CTC was increased with the increase in the T stage. The proportion of mesenchymal CTC was positively correlated with the N stage ( P < 0.05 ), and the larger N stage will have the higher proportion of mesenchymal CTC. Patients with a small number of mesenchymal CTC before neoadjuvant chemotherapy were more likely to achieve partial response (PR) with neoadjuvant therapy. Patients with positive CA-199 were more likely to achieve PR with neoadjuvant therapy ( P < 0.05 ). Patients in the PR group were more likely to have decreased/unchanged cfDNA concentration after neoadjuvant therapy ( P = 0.119 ). After neoadjuvant therapy (before surgery), the cfDNA concentration was higher and the efficacy of neoadjuvant therapy (SD or PD) was lower ( P = 0.045 ). Conclusions. Peripheral blood CTC, especially interstitial CTC and cfDNA, has a certain value in predicting the efficacy and prognosis of neoadjuvant chemotherapy in advanced gastric cancer.

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