Circulating cell free tumour derived nucleic acids are becoming recognised as clinically significant and extremely useful biomarkers for detection of cancer and for monitoring the progression of targeted drug therapy and immunotherapy. Screening programmes for colorectal cancer in Europe use the Fetal Immunochemical Test (FIT) test as a primary screener. FIT+ patients are referred to immediate colonoscopy and the positive predictive value (PPV) is usually 25%. In this article, we report a study employing the ColoScape assay panel to detect mutations in the APC, KRAS, BRAF and CTNNB1 genes, in order to collect preliminary performance indicators and plan a future, larger population study. The assay was evaluated on 52 prospectively collected whole-blood samples obtained from FIT+ patients enrolled in the CRC screening programme of ASL NAPOLI 3 SUD, using colonoscopy as confirmation. The assay’s sensitivity for advanced adenomas was 53.8% and the specificity was 92.3%. The PPV was 70.0% and negative predicitive value (NPV) was 85.7%. Workflow optimisation is essential to maximise sensitivity. Of note, four of the six positive cases missed by ColoScape had a less than suboptimal DNA input (data not shown). Had they been ruled out as inadequate, sensitivity would have increased from 53.8% to 69%. However, as stated previously, this is not a clinical trial, but rather an initial, preliminary technical evaluation. In conclusion this study shows that ColoScape is a promising tool and further studies are warranted in order to validate its use for the triage of FIT+ patients.
- mutational analysis
- liquid biopsy
- multiplex assay
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MS, JD and FP contributed equally.
Handling editor Runjan Chetty.
Contributors MS, FP-S, QS, MJP, UM and GT conceived the study and wrote the paper. FP and JD performed the experimental part. MAB and SRS performed the colonoscopy and tissue and blood samples collection.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests F-PS and MS are consultants of DiaCarta Inc. JD, QS and MJP are employees of DiaCarta Inc. Other authors have no competing interests to declare.
Patient consent Obtained.
Provenance and peer review Not commissioned; externally peer reviewed.
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