Friday, August 22, 2008

Commentary on Cytos' study for allergen-independent immunotherapy

Cytos is a Swiss-based company that is trying to develop vaccines that will fight diseases in human. On July 10, 2008, Cytos announced the results of trials studying CYT003-QbG10 in two randomized, double-blind, placebo-controlled, multicentre phase II studies with CYT003-QbG10 as monotherapy for the treatment of house dust mite and cat allergy, and with CYT005-AllQbG10 combination therapy for the treatment of house dust mite allergy. What were my thoughts on this?

The immune system has two functions: first, to recognize normally functioning cells from all other types of cells, bacteria, fungi, and viruses; second, to destroy this second group or remove it from the body. Some times the body mistakenly attacks something that it should ignore. In allergies, the body overreacts against allergens, like pollen, when it should take the milder approach of inactivating it. The immune system's reaction is very complex. Yet, scientist are getting closer and closer each year to understanding this reaction and then crafting a therapy to shut down this over-reaction in the case of allergies. Short sequences of synthetically made DNA were given the patients to distract their immune system from over-reacting to allergens. This type of immunotherapy was allergen-independent, in contrast to traditional allergen-dependent immunotherapy.

The trials involved 80 and 93 patients respectively, which is appropriate for a phase 2 study. However, remember that phase 2 trials are designed to demonstrate efficacy compared to a control group and further safety in humans. The trials did this, according to their announcement. I reserve further comments until after the trial is formally presented at scientific meetings and full details are published in a peer-reviewed medical journal. These two steps are essential. Cytos is the first company to my knowledge to be able to announce positive results with this type of therapy. They are not the only company working on this type of therapy. Allergen-independent immunotherapy is a concept that has been discussed for over 10 years. Getting a product approved is a monumental and expensive undertaking these days.

I hope Cytos will proceed with phase 3 trials, meaning larger numbers of subjects will be included in the trials. Some words of caution, many encouraging phase 2 trials did not pan out in phase 3 trials. Cytos' report hints that the testing was done only in Europe. I do not know if Cytos is testing their products with the U.S. F.D.A.'s approval in the U.S. If not, then these products will not be available for use for even longer, because the trials would have to be repeated in the U.S. and to the satisfaction of the U.S. F.D.A. Until then, allergists in the U.S. and the rest of the world will rely on traditional allergen-dependent immunotherapy. This was first described in a report by Dr. Noon in the Lancet in 1911. So we have nearly 100 years of experience using it. Immunotherapy can be very effective at increasing an allergic person's immune tolerance levels back up to normal, thus reducing their symptoms, signs, and medication use. We would also need long-term data about the efficacy, safety and duration of effects before having this therapy supplant traditional immunotherapy. Until then, allergists will keep using allergen-independent immunotherapy until a more effective, safer, and more cost-effective therapy becomes available. To quote the last line of The Count of Monte Cristo by Alexandre Dumas, "Wait and hope."

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