Liz Bond (1,6), Grégoire Thomas (2), Caroline Nolan (1,6), Peter Christensen (3), Phil Baker (4,6,7), Louise Kenny( 5,6,7), Robin Tuytten (1,6)
(1) Metabolomic Diagnostics, (2) Squ4Re, (3) Agilent Technologies, (4) The University of Auckland (5) Cork University Maternity Hospital ,on behalf of the IMPROvED (6) /SCOPE (7) consortium
Preeclampsia is one of the major complications of pregnancy. First time pregnant women have an increased risk for preeclampsia, yet routine prenatal care fails to accurately identify the 1st time pregnant women at risk. Basic biomarker research revealed that blood borne metabolites bear potential to risk-stratify for preeclampsia early in pregnancy. In a dedicated translational research effort, a prototype multiplex metabolite LC-MS assay was developed and then applied to a large case:control study focusing on 1st time pregnant women. This study confirmed that the newly discovered metabolite biomarkers enable prediction of preeclampsia risk early in pregnancy.
Preeclampsia is a hypertensive condition of pregnancy which is a leading cause of maternal and perinatal mortality and morbidity. First time pregnant women have an increased risk for preeclampsia, with about 5% of pregnancies affected. Screening for preeclampsia is a focus of prenatal care in many countries and is largely based on the use of clinical risk factors. Yet, the vast majority of first time pregnant women don’t have these risk factors, making the current screening unfit to determine preeclampsia risk in 1st time pregnant women.
Biomarkers have the potential to address this clinical need for a screening test for this group of pregnancies. In recent years it emerged that single biomarkers will not suffice to accurately predict preeclampsia as it is a very heterogeneous syndrome without a clear etiological pathway. As a result unbiased biomarker discoveries have been performed to identify panels of markers with combined preeclampsia prediction potential. Metabolite based solutions using mass spectrometry have gained significant interest as they are considered more readily translatable to clinical practice.
Here we report on the progress made in translating a biomarker discovery finding, which showcases that specific combinations of blood-borne metabolite biomarkers can risk-stratify pregnant women early in pregnancy (~15 weeks) according to their risk to develop pre-eclampsia (1), into a commercial LC-MS based clinical assay.
To tap into the large install base of quadrupole mass spectrometers (QqQ-MS) in clinical laboratories world-wide, a targeted LC -QqQ –MS approach was adopted. An analysis pipeline has been put in place constituting 1) a single step metabolite extraction, 2) multiplex LC-QqQ –MS assays for 40+ metabolites using stable isotope labelled standards for relative quantification and 3) a dedicated data processing protocol.
To verify the biomarker potential within the suite of metabolite biomarkers under investigation, one has to perform large scale studies in clinically relevant samples. In collaboration with the Screening fOr Pregnancy Endpoints (SCOPE) consortium (2), i.e., a large scale international prospective collection of first-time pregnancy biospecimens, a 1st case:control study constituting 15 weeks’ plasma samples from a group of 50 preclampsia destined women and a group of 500 control pregnant women was executed.
The possibility to risk stratify low risk 1st time pregnant women according to their preeclampsia risk later in pregnancy using panels of blood-borne metabolites was confirmed. Moreover, it was found that metabolites present in the blood of women at 15 weeks of gestation allows prediction of all types of preeclampsia. This underpins the potential of metabolite-centric multimarker panels to encapsulate a complex syndrome like preeclampsia well-in advance of its clinical manifestation.
These results pave the way for the further development of a novel, LC-MS based test which can complement current prenatal care screening programs with a test to identify preeclampsia risk within a group of women for whom current screening methodologies fail.
Further developments steps will include, amongst other, performing of additional case:control studies and subsequent clinical validation of this metabolite based test in the large scale European, multinational, multicentre phase IIa clinical study IMproved Pregnancy Outcomes by Early Detection (IMPROvED) (3) which is currently recruiting 1st time pregnant women in 5 European countries.
The authors gratefully acknowledge funding from the EU-HEALTH Project IMPROvED (305169) of the Seventh Framework Programme (FP7).
Metabolomic Diagnostics gratefully acknowledge the instrumentation and technical support received from Agilent Technologies – Ireland and Agilent Technologies US.
(1) Kenny, L. C. et al. Robust early pregnancy prediction of later preeclampsia using metabolomic biomarkers. Hypertension 56, 741–9 (2010).
(2) North, R. A. et al. Clinical risk prediction for pre-eclampsia in nulliparous women: development of model in international prospective cohort. BMJ 342, d1875 (2011).
(3) Navaratnam, K. et al. A multi-centre phase IIa clinical study of predictive testing for preeclampsia: improved pregnancy outcomes via early detection (IMPROvED). BMC Pregnancy Childbirth 13, 226 (2013).