The study compared pixantrone with the related drug, mitoxantrone, an agent currently approved to treat severe multiple sclerosis, also an autoimmune disease that attacks the central nervous system. In the current study, pixantrone was found to be more effective than mitoxantrone at improving both the laboratory and the clinical manifestations of the myasthenia gravis (MG) equivalent in rats.
In an in vitro rodent model, pixantrone demonstrated a dose-dependent inhibition of T cell responses up to complete suppression of the proliferation in EAMG. EAMG was induced in subject animals using acetylcholine (T-cell) receptor, the autoantigen at the neuromuscular junction. Doses of both pixantrone and mitoxantrone were equal to one-fourth of LD10 for single i.v. injection in animals. Although both pixantrone and mitoxantrone improved clinical symptoms, reduced weight loss and increased muscle acetylcholine receptor content compared with vehicle-treated rats, pixantrone appeared to be more effective at equitoxic doses.