Introduction

Although there is growing interest on prognostic and therapeutic value of KRAS mutations detection in pancreatic ductal adenocarcinoma (PDAC) patients’, the limited availability of sensitive, cost-effective and efficient molecular technologies has restricted its use. We present the fast single-step methodology utilizing amplification refractory mutation system (ARMS) coupled with high-resolution melting analysis (HRMA) to evaluate KRAS mutations and their prognostic value.

Aims & Methods

This is a prospective bicentric cohort study including PDAC patients with tumor samples collected at diagnosis. Codon-12/13 KRAS mutations were tested by Sanger Sequencing (SS) and the most frequent mutations were tested by ARMS/HRMA (G12D, G12V, G12R and G12C). Primary endpoint was the frequency of KRAS mutations by both techniques and their concordance. Secondary endpoints were the association of KRAS mutations and progression free survival (PFS) and overall survival (OS).

Results

83 patients, 57% male, with median-age at diagnosis of 70 (IQR 63-75) years-old, 55% submitted to upfront-surgery, 45% to palliative-chemotherapy or best-supportive care were included. SS detected KRAS mutations in 67% of tumor samples (G12D=47%, G12V=30%, G12R=13%, G12C=4%, G13V=4%, G12A=2%) and ARMS/HRMA in 82% (G12D=48%, G12V=35%, G12R=10%, G12C=2%, G12V/G12D=3%, G12D/G12C=2%) with a moderate concordance in mutation detection (kappa=0.517, p<0.001). Operated patients with G12C-mutated tumors had lower PFS (0 vs 8.5 months, HR=14.08 95%CI 1.435-138.207, p=0.023) and OS (0 vs 10 months, HR=11.49 95%CI 1.190-110.988, p=0.035) compared with wildtype tumors. No other differences were found in PFS and OS between KRAS-mutated and wildtype patients.

Conclusion

ARMS/HRMA appears to offer greater accuracy than SS in evaluating KRAS mutations in PDAC tumor samples, with the added benefits of speed and reduced costs. The presence of the G12C mutation was associated to lower OS and PFS, with early relapse after surgery. As such and with the recent emergence of drugs targeting G12C mutation (adagrasib), even resectable tumors might have indication for medical therapy, opening new avenues for personalized therapy in PDAC patients.