Lateral Flow Assay for Detection of Through Tumor Necrosis Factor Alpha (Infliximab) levels

The chimeric monoclonal antibody to tumor necrosis factor (TNF-α), infliximab,
is effective as an induction and maintenance therapy for patients with
moderate-to-severe Crohn*s disease including fistula closure. However, it*s use
is associated with the formation of antibodies to infliximab (ATIs) in 60% of
the patients, which may lead to infusion reactions, loss of efficacy and
delayed hypersensitivity reactions. The formation of infliximab-anti-infliximab
complexes leads to fast clearance of infliximab and lower serum infliximab
levels. This immunogenicity has important consequences for treatment outcome,
since lower drug levels are associated with shorter duration of response after
infusion9. In short, a good clinical response to treatment with infliximabi
correlates with the presence of high serum trough infliximab levels and the
absence of anti-infliximab antibodies, and inefficacy with the reverse. There
are several strategies that may prevent or overcome a loss of response. It has
been shown that ATI formation is less frequent when the drug is given as
scheduled maintenance therapy. Also, concomitant immunosuppressive therapy
(azathioprine or methotrexate) reduces immunogenicity and is associated with a
longer duration of response.

Monitoring of serum drug levels may help to optimize dosing schedules and
decrease the risk of infusion reactions and subsequent treatment failure. In
the future we want to routinely measure anti-TNF levels in IBD patients that
are treated with infliximab and correlate prospectively drug levels with
clinical and laboratory parameters (C-reactive protein and calprotectin). This
way we expect to gain insight whether and how drug level monitoring can predict
response to therapy and the development of adverse effects. The results could
be implicated in a therapeutic drug-monitoring-guided-therapy-strategy that may
have a safety and efficacy advantage for the individual patient. However, in
the current project we want to test lateral flow (LF)strips (see below) for
measuring serum levels of infliximab. Results will be compared to standard
laboratory testing by enzyme linked immunosorbent assay (ELISA). The ultimate
aim of this feasibility study is to develop a *lab on chip* analysis that can
be used in the future for therapeutic drug monitoring in a home care setting.

In the proposed study IBD patients that are treated with infliximab will be
asked to participate. A total of two blood samples will be taken from the
patients: pre- infusion and four weeks before/after infusion (the scheduled
time interval between two infusions is eight weeks). This will necessitate one
extra visit to the clinic for the four week sample. Blood samples will be
analyzed for serum infliximab levels by two methods: 1) standard ELISA test and
2) rapid assay format for multiplex detection (*lab on chip*). Results of both
analyses will be compared.

Burden: one extra venapuncture at week 4. No risk or imediate benefit.