Tackling Rheumatoid Factor Interference in ADA Assays using IgMBRAZOR™
Researchers at Roche have recently described an elegant solution to address the persistent problem of rheumatoid interference (RF) in anti-drug antibody (ADA) immunoassays. IgMBRAZOR is a unique IgM-specific protease that digests human IgM at one specific site below the CH2 domain in the heavy chain, generating homogeneous F(ab’)2 and Fc fragments. By introducing IgMBRAZOR pretreatment into their experimental setup, the scientists looked to digest IgM antibodies, including those responsible for RF interference, and effectively remove them from serum samples before ADA testing.
In the development of biologic drugs such as monoclonal antibodies (mAbs), monitoring ADAs is essential. These assays track whether a patient’s immune system produces antibodies against a therapeutic, as such responses can raise safety concerns and reduce drug efficacy. ADA assays, however, face a well-known challenge which is RF interference. RF, most often IgM antibodies, naturally present in some patients and can mimic ADA signals, leading to false positive results during bioanalytical testing. This not only complicates data interpretation but also raises regulatory concerns, since misleading ADA results can obscure the true immunogenic impact of a drug candidate.
Figure 1. IgMBRAZOR is a unique IgM-specific protease that digests human IgM at one specific site below the CH2 domain in the heavy chain, generating homogeneous F(ab’)2 and Fc fragments.
False positives in ADA assays have broad implications. They can mask clinically relevant IgG responses, misrepresent immunogenicity risks, and ultimately slow down the development of safe and effective therapies. IgMBRAZOR directly addresses this by eliminating IgM interference while leaving IgG, the isotype most often associated with long-term and clinically meaningful immune responses, unaffected. Importantly, introducing this pretreatment step is simple to apply. Because IgMBRAZOR can be added directly to serum samples, existing assay formats remain unchanged. This “plug-and-play” feature means labs can integrate the approach without redeveloping their workflows.
When applied to ADA bridging assays, IgMBRAZOR pretreatment significantly reduced assay signals in 6 of 8 donor samples analysed. Follow-up IgM-specific assays confirmed that these signals originated from IgM antibodies. Conversely, signals that persisted after treatment correlated with IgG-specific responses. As IgMBRAZOR abolished IgM signals but left IgG signals intact, this approach effectively builds ADA isotyping into the assay itself. In essence, signals which are eliminated after pretreatment can be attributed to IgM, while signals which remain after pretreatment originate from IgG. This built-in control provides critical biological insight, since IgM responses often represent short-lived immune activity, whereas IgG responses are more likely to impact therapeutic safety and efficacy.
The introduction of IgMBRAZOR supports a promising novel approach for ADA testing. By removing RF interference and streamlining isotyping, it enhances the accuracy, reliability, and efficiency of immunogenicity assessments. While additional validation in regulated bioanalytical environments will be needed, this approach represents a breakthrough in addressing one of the most persistent problems in immunoassay design. Better ADA data ultimately means better-informed decisions about drug safety and efficacy, and IgMBRAZOR may soon become a groundbreaking tool in advancing the next generation of biologic medicines!
Reference
Poehler et al., 2025. A Tool to Eliminate IgM Immunoassay Interference. The AAPS Journal.
IgMBRAZOR™ – Digestion of IgM