Analysis of BRCAness with multiplex ligation-dependent probe amplification using formalin-fixed and paraffin-embedded pancreatic ductal adenocarcinoma tissue obtained via endoscopic ultrasound-guided fine-needle aspiration biopsy

Clinicopathological Significance of BRCAness in Resectable Pancreatic Ductal Adenocarcinoma and Its Association With Anticancer Drug Sensitivity in Pancreatic Cancer Cells

OBJECTIVE

The concept of BRCAness has been proposed as a homologous recombination repair dysfunction triggered by a genetic defect in the BRCA pathway including the BRCA1/2 mutations. A certain number of pancreatic ductal adenocarcinoma (PDAC) patients have BRCAness. However, a large-scale analysis of BRCAness in PDAC has not been performed. In addition, no basic studies have examined the significance of BRCAness in PDAC cell lines.

METHODS

Ninety-two patients who underwent surgery for PDAC were enrolled. Formalin-fixed and paraffin-embedded specimens of resected PDACs were used to analyze BRCAness by multiplex ligation-dependent probe amplification. We also analyzed BRCAness in pancreatic cancer cell lines and the sensitivity to cisplatin and olaparib using a colony formation assay.

RESULTS

Of the 92 patients with PDAC, 6 were detected to have BRCAness-positive PDAC (6.5%). No significant differences in overall survival and progression-free survival were observed between the BRCAness-positive and BRCAness-negative groups. One PDAC cell line, KP-2, was positive for BRCAness and was more sensitive to cisplatin and olaparib than the BRCAness-negative cell lines.

CONCLUSIONS

Our results revealed that a considerable number of PDACs are positive for BRCAness, suggesting that BRCAness status could be a useful biomarker for selecting anticancer treatments for advanced or relapsed PDAC.

Feasibility of BRCA1/2 Testing of Formalin-Fixed and Paraffin-Embedded Pancreatic Tumor Samples: A Consecutive Clinical Series

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer, with most patients diagnosed at advanced stages. First-line treatment based on a combined chemotherapy (FOLFIRINOX or gemcitabine plus nab-paclitaxel) provides limited benefits. Olaparib, a PARP inhibitor, has been approved as maintenance for PDAC patients harboring germline BRCA1/2 pathogenic mutations and previously treated with a platinum-based chemotherapy. BRCA1/2 germline testing is recommended, but also somatic mutations could predict responses to PARP inhibitors. Analysis of tumor tissues can detect both germline and somatic mutations and potential resistance alterations. Few data are available about BRCA1/2 testing on pancreatic tumor tissues, which often include limited biological material. We performed BRCA1/2 testing, by an amplicon-based Next Generation Sequencing (NGS) panel, on 37 consecutive PDAC clinical samples: 86.5% of cases were adequate for NGS analysis, with a success rate of 81.2% (median DNA input: 10 nanograms). Three BRCA2 mutations were detected (11.5%). Failed samples were all from tissue macrosections, which had higher fragmented DNA than standard sections, biopsies and fine-needle aspirations, likely due to fixation procedures. BRCA1/2 testing on pancreatic tumor tissues can also be feasible on small biopsies, but more cases must be analyzed to define its role and value in the PDAC diagnostic algorithm.