Ki: 0.5-27 nM for RAR; 3.8-12 nM for RXR

9-cis-Retinoic acid (9cRA) is a RAR and RXR activator.

Metabolism activates vitamin A into retinoic acid (RA), which controls physiological processes such as nervous system function, immune response, cell proliferation and differentiation, as well as reproduction. Much of the activity of RA is mediated via two subfamilies of nuclear receptors, retinoic acid receptor (RAR) and retinoid X receptor (RXR).

In vitro: The 9cRA effect in pancreatic β-cells line INS-1 832/13 led to a decreased expression of Mptn associated to a concomitant increase of miR-375. Moreover, in the breast cancer model, 9cRA showed different effect on both Mtpn and miR-375 expression. Moreover, in INS-1 832/13, 3T3-L1 pre-adipocytes and MCF-7 but not in MDA-MB-231, the effect of 9cRA on Mptn gene expression and its miR was under the control of RARs and RXRs receptors [1].

In vivo: A chemoprevention study was conducted to evaluate the activity of 9cRA as an inhibitor of prostate carcinogenesis in male Wistar-Unilever rats. Results showed that continuous dietary administration of 9cRA reduced cancer incidence in the dorsolateral + anterior prostate. Similarly, 9cRA with same doses reduced the incidence of cancer in all accessory sex glands. Moreover, chronic dietary administration of 9cRA induced no gross or organ-specific toxicity and did not suppress group mean body weight gain [2].

Clinical trial: The impact of 9cRA on quality of life of alitretinoin in severe chronic hand eczema has been evaluated. At baseline, most patients had CHE characterized as severe by PGA (83 %). At last visit, 48 % of patients had a PGA response of clear/almost clear. Mean improvement in DLQI scores at week 24 was 58 % and 70 %. The overall incidence of AEs was low and similar in both groups [3].

References:
[1] Perri M, Caroleo MC, Liu N, Gallelli L, De Sarro G, Kagechika H, Cione E.? 9-cis Retinoic acid modulates myotrophin expression and its miR in physiological and pathophysiological cell models. Exp Cell Res. 2017 Mar 12. pii: S0014-4827(17)30126-X.
[2] McCormick DL, Rao KV, Steele VE, Lubet RA, Kelloff GJ, Bosland MC.? Chemoprevention of rat prostate carcinogenesis by 9-cis-retinoic acid. Cancer Res. 1999 Feb 1;59(3):521-4.
[3] Augustin M, Thai D, Kamps A.? Impact on quality of life of alitretinoin in severe chronic hand eczema: FUGETTA real-world study. J Dtsch Dermatol Ges. 2016 Dec;14(12):1261-1270.