ProStorm® Cytokine Release Assay
Mitigate risk as you approach a first-in-man trial
Monoclonal antibody therapeutics (mAbs) can cause infusion-related reactions in patients, which may only become apparent in first-in-man trials. To provide more information to drug developers before drugs reach clinical trials, ProImmune has developed ProStorm®, an in vitro cytokine release assay which can help to predict the likelihood of first infusion reactions.
Various types of infusion-related reactions may occur in response to biotherapeutics. First infusion reactions occur within minutes of infusion and depend on mAb interacting with their target and/or stimulating the innate immune system. Such reactions include cytokine release syndrome, and the related tumour lysis syndrome (which also leads to cytokine release). Symptoms of cytokine release syndrome range from fever, headache and skin rashes to bronchospasm, hypotension and even cardiac arrest. Severe cytokine release syndrome is described as cytokine storm, and can be fatal. Fatal cytokine storms have been observed in response to infusion with several mAb therapeutics,[1,2,3] and the cytokine storm reactions observed in first-in-man trials of TGN1412 ignited public and industry concern relating to early-stage mAb trials. ProStorm® is designed specifically to indicate when a cytokine storm first infusion reaction may be a risk for a therapeutic.
The ProStorm® assay uses fresh whole blood sourced from 20-50 healthy volunteer donors recruited for your study by ProImmune. To maximise assay sensitivity, blood is used undiluted, and drugs are added in a range of concentrations to cover the peak exposure range of drugs in the body. Following incubation, cytokine release is measured using ProImmune’s high-sensitivity ProArray Ultra® platform, to give an accurate profile of cytokine release. TNFα, IFNɣ, IL-2, Il-4, Il-6, IL-8 and IL-10 levels are measured. As an option, Erbitux®(Cetuximab), associated with a low incidence of first infusion reactions in the clinic, is typically included in the ProStorm® assay to provide a baseline, and Campath® (Alemtuzamab), which frequently causes first infusion reactions, is typically included as a biologically relevant comparator. In reporting the assay data, we include analysis of the significance and dose-dependency of responses for test drugs.
To harmonize methods for prediction of cytokine release assays, the European Medicines Agency (EMA) held a workshop in 2009. They agreed that animal models are not predictive of first infusion reactions, so in vitro cytokine release assays (such as ProStorm®) are best for identifying this hazard. The EMA also advise that users of in vitro assays should consider absolute and relative changes in cytokine release profiles and use biologically relevant comparators in their analysis, exactly as ProStorm® does.
Predictive assays such as ProStorm® can be used by drug developers to mitigate risk when approaching first-in-man trials. ProStorm® cannot be used to quantify risk, but if a potential hazard is indicated then trials can be designed with this in mind. For example, a lower starting dose can be chosen, and antihistamines and steroids can be administered in advance of the drug infusion to mitigate potential reactions. TGN1412 was an unusual case: first-infusion reactions do not usually spell the end for a therapeutic. Many established therapeutics, including Ofatumamamb (Arzerra), Adalimumab (HUMIRA) and Infliximab (Remicade®), [7,8,9] have high incidences of first infusion reactions. Prior information on the risks of a first infusion reaction allows this risk to patients to be managed, so that the drugs can still be applied successfully and widely adopted by clinicians. ProStorm® can thus be a valuable tool, providing information that may help in bringing a therapeutic to market.