Hopes have been dashed for a potential treatment for peanut allergies following the severe reactions suffered by two children during a clinical trial.

Biotech company Genentech, Inc. has now stopped the trials.

Genentech is one of the largest biotech companies in the world, and was conducting clinical trials of their drug Xolair in order to test whether the drug could prevent reactions to peanut allergies.

Of the 150 children in the trial, two apparently experienced “severe hypersensitivity reactions” to a trace amount of peanut protein.

It seems the children had not been given Xolair, but were given the protein to test their reactions.

According to a Genentech spokeswoman they will not carry out that procedure again.

Xolair is already available on the market as a treatment for allergic asthma and it is not uncommon for drug manufacturers to test products for additional uses after they’ve already been approved.

Genentech’s top-selling products are Rituxan, a treatment for non-Hodgkin’s lymphoma and Avastin, a treatment for colorectal cancer.