Clinical significance of clonal hematopoiesis in the interpretation of blood liquid biopsy

Abstract

As the use of next‐generation sequencing (NGS) for plasma cell‐free DNA (cfDNA) continues to expand in clinical settings, accurate identification of circulating tumor DNA mutations is important to validate its use in the clinical management for cancer patients. Here, we aimed to characterize mutations including clonal hematopoiesis (CH)‐related mutations in plasma cfDNA and tumor tissues using the same ultradeep NGS assay and evaluate the clinical significance of CH‐related mutations on the interpretation of liquid biopsy results. Ultradeep targeted NGS using Oncomine Pan‐Cancer Panel was performed on matched surgically resected tumor tissues, peripheral blood cells (PBCs), and 120 plasma cfDNA samples from 38 colorectal cancer patients. The clinical significance of the CH‐related mutations in plasma cfDNA was evaluated by longitudinal monitoring of the postoperative plasma samples. Among the 38 patients, 74 nonsynonymous mutations were identified from tumor tissues and 64 mutations from the preoperative plasma samples. Eleven (17%) of the 64 mutations identified in plasma cfDNA were also detected in PBC DNA and were identified to be CH‐related mutations. Overall, 11 of 38 (29%) patients in this cohort harbored at least one CH‐related mutation in plasma cfDNA. These CH‐related mutations were continuously detected in subsequent postoperative plasma samples from three patients which could be misinterpreted as the presence of residual disease or as lack of treatment response. Our results indicated that it is essential to integrate the mutational information of PBCs to differentiate tumor‐derived from CH‐related mutations in liquid biopsy analysis. This would prevent the misinterpretation of results to avoid misinformed clinical management for cancer patients.

Evolution of Mutational Landscape and Tumor Immune-Microenvironment in Liver Oligo-Metastatic Colorectal Cancer

“…Liver is the most typical site of distant spread (about 50% of patients), followed by non-regional lymph nodes, lungs, and peritoneum. Bone, brain, and other sites are infrequent targets of metastatic spread [ 7 , 8 ].…”

Clonal Hematopoiesis in Liquid Biopsy: From Biological Noise to Valuable Clinical Implications

“…CH mutations detected from plasma are similar to the mutations detected from white blood cells, involved both canonical CH genes, DNMT3A , TET2 , ASXL1 and JAK2 , and actionable mutations in genes related to solid tumors, KRAS , PIK3CA and EGFR [ 56 , 64 , 73 , 75 ]. Majority of these identified CH variants have been previously reported as tumor-associated somatic mutations which complicate the curation of the variants detected in cfDNA analysis [ 76 , 77 ]. A total of 656 distinct TP53 variants have been reported as CH mutations in 14 previous studies [ 5 , 50 , 51 , 52 , 55 , 58 , 64 , 72 , 73 , 74 , 75 , 76 , 77 , 78 ] and up to 99% (650/656) of these mutations have been documented in the COSMIC database as somatic mutations detected in solid tumors.…”

“…Majority of these identified CH variants have been previously reported as tumor-associated somatic mutations which complicate the curation of the variants detected in cfDNA analysis [ 76 , 77 ]. A total of 656 distinct TP53 variants have been reported as CH mutations in 14 previous studies [ 5 , 50 , 51 , 52 , 55 , 58 , 64 , 72 , 73 , 74 , 75 , 76 , 77 , 78 ] and up to 99% (650/656) of these mutations have been documented in the COSMIC database as somatic mutations detected in solid tumors. Further stratification to focus on the most frequently mutated TP53 variants in CH showed these hotspot variants coincide with the most frequently mutated TP53 variants in solid tumors ( Figure 3 ).…”

“…VAF of CH mutations detected from plasma are highly correlated and indifferent to the VAF detected in white blood cells [ 73 , 75 ] which highlights the importance of sequencing white blood cells to at least the same depth as cfDNA to correctly exclude the CH mutations and avoid misinterpretation. Furthermore, our group has recently shown there are no significant differences between the VAF of CH-related and tumor-derived ctDNA detected in plasma samples [ 76 ]. The indifferences in the type of variant and VAF between CH and ctDNA mutations reinforce the difficulties to differentiate them without performing paired deep sequencing of plasma cfDNA and DNA from white blood cells.…”

“…The theory that underlies this approach is that all mutations detected from tumor tissues would be specific to the malignancy. However, such an approach should also be carefully considered as CH mutations may also be present in tumor tissues due to tumor-infiltrating blood cells [ 53 , 63 , 76 ]. Two large retrospective studies analyzed existing NGS data of paired tumor tissues and white blood cells from thousands of cancer patients with various solid tumors to assess the prevalence of CH mutations in tumor tissues [ 53 , 63 ].…”