Improvement in psoriasis after intradermal administration of delipidated, deglycolipidated Mycobacterium vaccae (PVAC (TM)): results of an open-labeltrial

The aim of new treatments for psoriasis is to induce extended remissions wi th fewer side-effects. Previous studies suggest that Mycobacterium vaccae, a harmless organism prepared as a heat-killed suspension, may induce period s of remission in some psoriasis patients after intradermal administration. To assess a more potent derivative of M. vaccae, we conducted an open-labe l study in which 20 patients with moderate to severe psoriasis (Psoriasis A rea and Severity Index of 12-35) received two intradermal inoculations of h eat-killed, delipidated, deglycolipidated M. vaccae (DD-MVAC or 'PVAC') in lesion-free deltoid skin, separated by a period of 3 weeks. Twelve weeks af ter the injections, 13 out of 20 patients (65%) showed marked improvement i n the PASI score (> 50% reduction), three were unchanged (< 25% reduction), three had worsened (> 5% increase), and one was withdrawn from the trial b ecause of an exfoliative flare. At 24 weeks, 13 out of 19 patients continue d to show > 50% improvement that, in some, lasted for 6 months or longer. P atients classified as good responders at 12 or 24 weeks were then offered a dditional PVAC injections after 24 weeks if the PASI reached 8 or higher. I ntra-dermal administration of PVAC was safe, well tolerated, and induced cl inically significant improvement in many psoriasis patients. A randomized, double-blind, controlled study is warranted.