ELISA versus Mass Spectrometry for the Detection of HCPs
Host cell proteins or traces thereof can be found in the end products of biologics. This includes antibodies, antigens, peptides and proteins. These products can be frequently used for vaccines and the treatment of serious diseases, such as cancer and diabetes.
ELISA is a commonly used immunoassay for the detection of HCP. ELISA stands for "enzyme immunoassay" and is based on the use of polyclonal antibodies that have been raised against the host cells used in the fermentation process. ELISA assays have dominated HCP detection assays as they can provide high throughput, high sensitivity, and high selectivity. Moreover, ELISA is simpler and more economical compared to mass spectrometry.
ELISAs are able to detect most HCPs. However, due to the severe deleterious effect of HCPs, full reagent coverage of 100% immunoreactivity is required to ensure removal of all possible HCP impurities. But this cannot be achieved using ELISA.
The associated risk depends on the coverage of ELISA reagents and the likelihood of immunologically unreactive PHCs persisting downstream, which can be potentially harmful. In addition, the development of an ELISA test can take up to eight months.
Mass spectrometry
Mass spectrometry measures a range of parameters that is not possible with ELISA. With mass spectrometry it is possible to identify even low abundance PHCs in addition to measuring the impurity profile of the product.
Mass spectrometry has only recently been introduced as a viable alternative to ELISAs for HCP analysis, due to uncertainties surrounding the required sensitivity and dynamic range, in addition to reasonable time efficiency. Tandem time-of-flight (ToF) mass spectrometry is often used.
Mass spectrometry has successfully detected HCPs that have known effects on drug efficacy or patient safety and has been used to oversee the clearance of individual HCPs.