168P - Usefulness of liquid biopsy in the management of patients with advanced or metastatic pancreatic cancer

Background

Routine genomic profiling in metastasic solid tumors has an impact on survival by selecting targeted therapies and montoring treatment response. Moreover, feasibility and efficiency of liquid biopsy (LB) in pancreatic cancer has been studied as tissue is not always available in these tumors given the frequent lack of tissue in these tumors.

Methods

We present an ambispective observational study in patients with locally advanced or metastatic pancreatic cancer who underwent LB before starting chemotherapy. The primary end point was to determine the prevalence of pathological molecular alterations in circulating tumor DNA (ctDNA) and their concordance with next generation sequencing in tumor tissue (TNGS). A secondary end point was the study of circulating tumor cells (CTCs) as a poor prognostic factor for survival.

Results

A total of 30 patients were included between May 2020 and September 2022. Women were 53.3% of them, and the median age was 65.5 years (37-85). At the time of LB, 86.7% had metastatic disease, 6.7% had stage III, and 6.7% had stage II. 83.4% were about to initiate a first-line chemotherapy. 86.7% of the patients had also undergone TNGS. In both LB and TNGS, one or more molecular alterations were found in 80% of patients. Fourteen different molecular alterations were found in LB, with the most prevalent mutations in TP53 (56.6%), KRAS (53.3%), ERBB2 (16.6%), MET (4%), and EGFR (4%). In TNGS, 12 alterations were found, with the most prevalent being TP53 (46.6%), KRAS (60%), MET (23.3%), and EGFR (13.3%). The concordance rate between BL and TNGS was > 70%. The median overall survival (OS) was 5.5 months (95%CI:3.6-7.4). In patients without CTCs, the OS was 6.3 months (95%CI:4.7-8.0), while patients with CTCs had an OS of 3.6 months (95%CI:1.6-5.6).

Conclusions

80% of patients presented molecular alterations in both LB and TNGS with a matching rate > 70%. The most prevalent mutations were TP53, KRAS, MET, EGFR and ERBBE in the two analyses. The presence of CTCs is a poor prognostic factor.

Editorial acknowledgement

Clinical trial identification

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.