Immunoassays Compared for Serum HE4 Estimation for Ovarian Cancer

Ovarian cancer is the sixth most common cancer in women and the leading cause of death from gynecological malignancy in the UK. Cancer antigen 125 (CA125) is the most widely used diagnostic biomarker for ovarian cancer; however it lacks the diagnostic accuracy to reliably detect ovarian cancer at an early stage.

There has been growing interest in human epididymis protein 4 (HE4), a protein found on cells that line the lungs and reproductive organs, such as the ovaries, as an additional serum biomarker for ovarian cancer. With clinical use of HE4 expanding, a high throughput automated assay that allows multiple samples to be analyzed rapidly is needed.

Medical Scientists at the Manchester Academic Health Science Centre (Manchester UK) and their colleagues compared two immunoassay methods for the measurement of serum HE4. The study population included all primary care requested serum CA125 samples received by the Manchester University NHS Foundation Trust (MFT) Clinical Biochemistry laboratory between April 2018 and April 2019.

The team analyzed 1,348 serum samples for serum HE4 using both the conventional manual enzyme immunometric-assay (EIA), and an automated chemiluminescent immunoassay (CLEIA) methods. Samples were analyzed using the HE4 EIA (Fujirebio, Gent, Belgium) and the Lumipulse G600II analyzer also from Fujirebio. The EIA is a solid phase non-competitive immunoassay using mouse monoclonal antibodies (MAb) 2H5 and 3D8 directed against different HE4 epitopes. The maximum detection limit is 900 pmol/L. The CLEIA uses a two-step sandwich immunoassay technique. The immunoreaction cartridges contain two monoclonal antibodies, MAb 2H5 and alkaline phosphatase (ALP)-labeled MAb 12A2. The maximum detection limit is 1,500 pmol/L.

The investigators demonstrated in their study a significant difference in serum HE4 values measured using CLEIA and conventional EIA. There was moderate agreement between the two methods, but CLEIA significantly overestimated HE4 values when compared to EIA, with a mean percentage bias of 16.25%. Identified biases of 7.2 pmol/L and 10 pmol/L, at the thresholds of 70 pmol/L and 140 pmol/L respectively, are likely to significantly impact clinical interpretation and decision making when using values measured by the CLEIA, highlighting the importance of assay-specific cut-offs for clinical application.

The authors concluded that the CLEIA significantly overestimates HE4 values compared to the EIA, suggesting that a common clinical decision limit may not be appropriate. The study was published in the August, 2021 issue of the journal Practical Laboratory Medicine.

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Manchester Academic Health Science Centre
Fujirebio