Endotoxin and cancer chemo-prevention

Reduced rates of lung cancer have been observed in several occupational groups exposed to high levels of organic dusts contaminated by endotoxin. The underlying anti-neoplastic mechanism of endotoxin may be an increased secretion of endogenous anti-neoplastic mediators and activation of the toll-like receptors (TLR). A detoxified endotoxin derivative, Monophosphoryl Lipid A (MPL®) is marketed in Europe since 1999 as part of the adjuvant systems in allergy vaccines for treatment of allergic rhino-conjunctivitis and allergic asthma. Over 200,000 patients have used them to date (nearly 70% in Germany). Since detailed exposure (MPL® dose and timing of administration) and individual data are potentially available, an observational follow-up study could be conducted in Germany to investigate the protective effect of MPL® against cancer, comparing cancer incidence in two groups of patients with allergic rhinitis: those treated with allergoids plus MPL® and those treated with a vaccine including the same allergoids but not MPL®. The protective effect of MPL® could be quantified in ever and never smokers. If this proposed observational study provides evidence of protective effects, MPL® could be immediately used as a chemo-preventive agent since it is already in use as adjuvant in human vaccines against cancer.