Circulating epigenetic biomarkers for detection of recurrent colorectal cancer

Abstract

Background The sensitive detection of recurrent colorectal cancer (CRC) by the measurement of circulating tumor DNA (ctDNA) might improve the chance of a cure. This study compared a quantitative methylated ctDNA test with carcinoembryonic antigen (CEA) in the setting of surveillance for recurrence. Methods Blood samples collected either during surveillance or within 12 months of the confirmation of recurrence were assayed for ctDNA (methylated branched‐chain amino acid transaminase 1 [BCAT1]/Ikaros family zinc‐finger 1 protein [IKZF1]) and CEA. The optimal ctDNA threshold was determined by receiver operating characteristic analysis, and the test performance for the detection of recurrence was compared with CEA (5 ng/mL threshold). Results The study cohort comprised 144 eligible patients and included 50 recurrence events. The sensitivity of the methylated ctDNA test for recurrence was 66.0% (95% confidence interval [CI], 57.1%‐69.3%), which was significantly higher than the sensitivity of CEA (31.9%; 95% CI, 22.8%‐36.6%; P < .001). The sensitivity for resectable recurrence (n = 20) was also higher (ctDNA, 60.0%; CEA, 20.0%; P = .01). The specificity did not differ between the tests (ctDNA, 97.9%; 95% CI, 93.2%‐99.6%; CEA, 96.4%; 95% CI, 91.4%‐99.0%). When adjustments were made for other predictors of the presence of recurrence, a positive ctDNA test was an independent predictor (odds ratio, 155.7; 95% CI, 17.9‐1360.6; P < .001), whereas CEA was not (odds ratio, 2.5; 95% CI, 0.3‐20.6; P = .407). Conclusions The quantitative ctDNA test showed superior sensitivity in comparison with CEA without a difference in the specificity for detecting recurrent CRC. Longitudinal studies are warranted to further assess the utility (specifically the survival benefit) of methylated BCAT1/IKZF1 ctDNA in the surveillance of patients with CRC.

Evaluation of Circulating Tumor DNA for Methylated BCAT1 and IKZF1 to Detect Recurrence of Stage II/Stage III Colorectal Cancer (CRC)

“…Because earlier detection of CRC recurrence may facilitate potentially curable metastasectomy, the application of a more sensitive assay, such as one targeting hypermethylated BCAT1 and IKZF1 ctDNA, during surveillance might improve outcomes in recurrent CRC. Consistent with published data showing that methylation alterations to BCAT1 and IKZF1 can be identified in plasma well before radiographic recurrence (25,28,30,31,33), the current study demonstrated COLVERA positivity up to six months before imaging suggested recurrence. Nevertheless, without directly comparing results of regimented serial CEA and radiographic surveillance with serial ctDNA and radiographic surveillance, it is impossible to know whether application of ctDNA will lead to earlier radiographic detection and, most importantly, whether earlier radiographic detection will translate into improved cancer-related outcomes.…”

“…The findings of the present study are consistent with prior investigation into the utility of methylation biomarkers (30,33) for CRC surveillance. For example, Australian and Chinese studies showed that circulating methylated BCAT1/IKZF1 and SEPT9, respectively, were more sensitive than CEA in detecting CRC recurrence (33,39,40).…”

“…In summary, this study confirms the findings of prior studies using methylated BCAT1 and IKZF1 (30,33) to detect CRC recurrence. In both the U.S. and Australian cohorts, head-to-head comparison of COLVERA to CEA at a single time-point confirmed that COLVERA detected more radiologically confirmed recurrences.…”

“…Since CEA and COLVERA results were correlated with only one imaging test, it is possible that some subjects deemed without recurrence were later proven to have recurrent disease after further imaging. Indeed, a recent study showed that adding a second negative CT to confirm recurrence status improves ctDNA specificity (33). More than half of evaluable subjects without recurrence in the present study were still within the first two years of surveillance when their blood was sampled and CT report documented.…”

“…This high level of aberrant methylation in CRC makes these biomarkers an attractive choice for CRC recurrence monitoring regardless of underlying CRC molecular genotype. Retrospective observational studies conducted in Australia have already shown that COLVERA™, a qualitative blood test that detects methylated BCAT1 and IKZF1 in cfDNA, is more sensitive than and as specific as CEA for predicting recurrence in patients undergoing surveillance after resection of primary CRC (30,33). Because reliability of cancerspecific methylation assays may vary based on age, race, and ethnicity, validation of epigenetic biomarkers in a diverse population of patients is warranted to ensure generalizability (34).…”