The Pharmaceutical Journal
Vol 270 No 7244 p507
12 April 2003

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Monoclonal antibody may provide protection for peanut allergy sufferers

An experimental monoclonal antibody may provide protection against the effects of accidental peanut ingestion in peanut allergy sufferers, researchers report.

Dr Donald Leung, National Jewish Medical and Research Centre, Denver, and colleagues say that for patients with peanut allergy there is currently no adequate treatment for, or protection against, accidental ingestion of peanuts other than avoidance, although adrenaline modulates the reaction and can be lifesaving.

However, the researchers have found a humanised IgG1 monoclonal antibody against IgE, TNX-901, that, at a dose of 450mg administered subcutaneously every four weeks, substantially increases threshold peanut antigen sensitivity to a level that should provide at least partial protection against most unintended peanut ingestion. TNX-901 recognises and masks an epitope in a region of IgE responsible for binding to high-affinity receptors for IgE on mast cells and basophils.

Data were analysed for 82 patients with a history of peanut allergy manifested by urticaria, angioedema, lower respiratory tract symptoms or hypotension Subjects were randomly assigned to receive TNX-901 150mg, 300mg or 450mg or placebo subcutaneously every four weeks for four doses. Threshold doses of encapsulated peanut flour were established at screening.

THX-901 450mg increased the threshold of peanut sensitivity from a level equivalent to approximately half a peanut to one equal to almost nine peanuts (the average amount of peanut consumed in an accidental exposure is believed to be not more than one or two peanuts, although this has not been accurately quantified, the researchers say). A total of 21 per cent of patients in the 300mg group (n=19) and 24 per cent in the 450mg group (n=21) were effectively desensitised and able to ingest about 24 peanuts, the final dose in the food challenge, before having a reaction.

The researchers conclude that, although the results are encouraging, "TNX-901 is still an experimental drug and approval for general use will require confirmation of these results in additional studies" (New England Journal of Medicine 2003;348:986).