Efficacy and Safety of Tamibarotene(AM80) for Lupus Nephritis

Tamibarotene is a synthetic retinoid presently approved in Japan for the treatment of APL, and in US, Europe and China it is still under development for APL. Compared to other retinoid drugs available, Tamibarotene has not just a higher activity as a retinoid, but also shows a higher receptor selectivity towards the Retinoic Acid Receptor (RAR) subtypes alfa and beta, but not gamma. All trans retinoic acid (ATRA) and its derivatives are usually pan-agonists to these subtypes, and often are know for the irritation to the skin as one of their major side effects which is due to the RAR gamma subtype. Moreover, unlike ATRA tamibarotene does not cause induction of drug metabolism by CRABP. Tamibarotene is known to moderate T1/T2 balance as well as Treg/Th17 balance through binding RAR-alfa receptor, and shows efficacy to various autoimmune and inflammatory animal models. In the preliminary clinical research, patients with lupus nephritis for whom prednisolone treatment was not sufficient enough was treated with oral administration of ATRA to show a remarkable decrease in their protein urea (ref. Kinoshita et al, Am.J.Kidney Dis., 2009 Jul 21). Based on these results, the investigators plan by this study to evaluate the efficacy of tamibarotene together with the safety to the patients of lupus nephritis. Tamibarotene is used clinically in Japan since 2005. It's side effects are known to be similar to that of other clinically used retinoids.