A potential asthma vaccine that received widespread media publicity last weekend has so far only undergone preliminary testing.
A British Association for the Advancement of Science meeting on September 17 heard an account of a phase II study with the vaccine (called SRL172) conducted by Professor Stephen Holgate's asthma research group at Southampton university.
The study was carried out to assess the effect of the vaccine on allergen-induced bronchoconstriction and airway hyper-responsiveness in patients with mild to moderate asthma. Twelve patients received a single dose of SRL172 and 12 received placebo. The average late-phase airway response to a standardised allergen challenge was significantly reduced in the active treatment group, and these patients also had beneficial changes in immunological markers of airway inflammation.
SRL172 is a killed suspension of a strain of Mycobacterium vaccae. Its manufacturer, SR Pharma, is now hoping to set up a phase III asthma study and is in negotiation with prospective licensing partners. The vaccine is designed to manipulate the immune system, switching the balance of CD4 T-helper cells from a Th2 response (associated with allergy) to a Th1 response (PJ 1998;261:890). It is also being tested in certain cancers.
SRL172 was originally investigated in tuberculosis. It was hoped that it would boost the immune response and act as an adjunct to chemotherapy. However, a major trial in tuberculosis found no benefit from treatment and SR Pharma has stopped this line of research.