Circulating tumour DNA (ctDNA) as a biomarker in metachronous melanoma and colorectal cancer- a case report

• Published in: BMC cancer Vol. 19; no. 1; pp. 1109 - 5
• Main Authors: Calapre, Leslie, Warburton, Lydia, Millward, Michael, Gray, Elin S
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 14-11-2019; BioMed Central; BMC
• Subjects: Aged; Antineoplastic agents; Apoptosis; Bevacizumab; Biomarkers, Tumor - blood; BRAF; Cancer genetics; Cancer metastasis; Cancer patients; Cancer treatment; Case Report; CAT scans; Circulating tumor DNA; Circulating Tumor DNA - blood; Colon cancer; Colorectal cancer; Colorectal Neoplasms - blood; Colorectal Neoplasms - pathology; CTLA-4 Antigen - antagonists & inhibitors; CTLA-4 Antigen - genetics; Dabrafenib; Development and progression; Diagnostic imaging; Disease Progression; DNA; EDTA; Humans; Immunotherapy; Ipilimumab; Male; Melanoma; Melanoma - blood; Melanoma - pathology; Melanoma - secondary; Mutation; Necrosis; Neoplasms, Second Primary - blood; Neoplasms, Second Primary - drug therapy; Neoplasms, Second Primary - genetics; Neoplasms, Second Primary - pathology; Patient monitoring equipment; Pembrolizumab; Programmed Cell Death 1 Receptor - antagonists & inhibitors; Programmed Cell Death 1 Receptor - genetics; Proto-Oncogene Proteins B-raf - blood; Proto-Oncogene Proteins p21(ras) - blood; Survivorship; Trametinib; Tumors; Case report; BRAF; Colon cancer; Survivorship; Circulating tumor DNA; Melanoma
• ISSN: 1471-2407; 1471-2407
• DOI: 10.1186/s12885-019-6336-3

Circulating tumour DNA (ctDNA) has emerged as a promising blood-based biomarker for monitoring disease status of patients with advanced cancers. The presence of ctDNA in the blood is a result of biological processes, namely tumour cell apoptosis and/or necrosis, and can be used to monitor different cancers by targeting cancer-specific mutation.
We present the case of a 67 year old Caucasian male that was initially treated with BRAF inhibitors followed by anti-CTLA4 and then anti-PD1 immunotherapy for metastatic melanoma but later developed colorectal cancer. The kinetics of ctDNA derived from each cancer type were monitored targeting BRAF V600R (melanoma) and KRAS G13D (colon cancer), specifically reflected the status of the patient's tumours. In fact, the discordant pattern of BRAF and KRAS ctDNA was significantly correlated with the clinical response of melanoma to pembrolizumab treatment and progression of colorectal cancer noted by PET and/or CT scan. Based on these results, ctDNA can be used to specifically clarify disease status of patients with metachronous cancers.
Using cancer-specific mutational targets, we report here for the first time the efficacy of ctDNA to accurately provide a comprehensive outlook of the tumour status of two different cancers within one patient. Thus, ctDNA analysis has a potential clinical utility to delineate clinical information in patients with multiple cancer types.