ADAM12 as a novel marker for the diagnosis of ectopic pregnancy

Abstract

OBJECTIVE: Ectopic pregnancy (EP) is major cause of maternal morbidity and mortality in the first trimester, and there is currently no single test for its early diagnosis and treatment. The goal of this study was to evaluate the performance of a novel biomarker, a disintegrin and metalloprotease-12 (ADAM12), to differentiate EP from normal intrauterine pregnancies (IUP).DESIGN: Case-control.MATERIALS AND METHODS: Serum was collected as part of the PEP study (predictors of EP) from patients who presented to three sites with a symptomatic first trimester pregnancy. 18 serum samples (9 EP and 9 IUP) were selected for proteomics evaluation. Samples were depleted of 20 abundant proteins, separated by SDS-PAGE, sliced into 20 fractions, and digested with trypsin. Digests were analyzed by LC-MS/MS followed by label-free pattern analysis to identify significant changes between EP and IUP. 5 candidate biomarkers from the discovery analysis were selected for initial validation with Multiple Reaction Monitoring (MRM). The best performing marker, ADAM12, was selected for further evaluation in serum from 99 women with EP and 100 women with IUP using a dissociation-enhanced lanthanide fluoroimmunoassay (DELFIA).RESULTS: The proteomics analysis found a statistically significant decrease in ADAM12 in the sera of patients with EP compared to those with an IUP with good discrimination (p=0.02, AUC=0.81). When we then looked at ADAM12 in the sera of 199 patients using the DELFIA method, we again found a highly significant decrease in ADAM12 in the EP group (median 2.5ng/ml) compared to IUP (median IUP 18.6ng/ml, p <0.0001). There is good discrimination between the groups as assessed by receiver operating characteristics (AUC=0.82). Depending on the cut off, the marker can maximize specificity (86%) or sensitivity (97%).CONCLUSION: Validating a proteomic discovery approach, ADAM12 is a promising serum marker for the diagnosis of ectopic pregnancy. OBJECTIVE: Ectopic pregnancy (EP) is major cause of maternal morbidity and mortality in the first trimester, and there is currently no single test for its early diagnosis and treatment. The goal of this study was to evaluate the performance of a novel biomarker, a disintegrin and metalloprotease-12 (ADAM12), to differentiate EP from normal intrauterine pregnancies (IUP). DESIGN: Case-control. MATERIALS AND METHODS: Serum was collected as part of the PEP study (predictors of EP) from patients who presented to three sites with a symptomatic first trimester pregnancy. 18 serum samples (9 EP and 9 IUP) were selected for proteomics evaluation. Samples were depleted of 20 abundant proteins, separated by SDS-PAGE, sliced into 20 fractions, and digested with trypsin. Digests were analyzed by LC-MS/MS followed by label-free pattern analysis to identify significant changes between EP and IUP. 5 candidate biomarkers from the discovery analysis were selected for initial validation with Multiple Reaction Monitoring (MRM). The best performing marker, ADAM12, was selected for further evaluation in serum from 99 women with EP and 100 women with IUP using a dissociation-enhanced lanthanide fluoroimmunoassay (DELFIA). RESULTS: The proteomics analysis found a statistically significant decrease in ADAM12 in the sera of patients with EP compared to those with an IUP with good discrimination (p=0.02, AUC=0.81). When we then looked at ADAM12 in the sera of 199 patients using the DELFIA method, we again found a highly significant decrease in ADAM12 in the EP group (median 2.5ng/ml) compared to IUP (median IUP 18.6ng/ml, p <0.0001). There is good discrimination between the groups as assessed by receiver operating characteristics (AUC=0.82). Depending on the cut off, the marker can maximize specificity (86%) or sensitivity (97%). CONCLUSION: Validating a proteomic discovery approach, ADAM12 is a promising serum marker for the diagnosis of ectopic pregnancy.