Chloroquine-d5 is intended for use as an internal standard for the quantification of chloroquine by GC- or LC-MS. Chloroquine is an aminoquinoline that is an inhibitor of autophagy and has antimalarial and anticancer activities.1,2,3 Chloroquine inhibits autophagosome-lysosome fusion in HeLa cells when used at a concentration of 100 μM.1 It is active against the chloroquine-sensitive GC03 strain of P. falciparum (IC50 = 29.2 nM) but has decreased activity against mutant pfcrt P. falciparum (IC50s = 100-150 nM).2 Chloroquine inhibits the growth of human SSC25 and CAL27 oral squamous cell carcinoma cells (IC50s = 29.9 and 17.3 μM, respectively), as well as A498, SN12C, RXF393, and 769-P renal cancer cells (IC50s = 16, 62, 81, and 25 μM, respectively).3,4 It reduces tumor growth in a CAL27 mouse xenograft model and a 4T1 mouse allograft model when administered at a dose of 50 mg/kg.3,5

|1. Mauthe, M., Orhon, I., Rocchi, C., et al. Chloroquine inhibits autophagic flux by decreasing autophagosome-lysosome fusion. Autophagy 14(8), 1435-1455 (2018).|2. Sidhu, A.B.S., Verdier-Pinard, D., and Fidock, D.A. Chloroquine resistance in Plasmodium falciparum malaria parasites conferred by pfcrt mutations. Science 298(5591), 210-213 (2002).|3. Jia, L., Wang, J., Wu, T., et al. In vitro and in vivo antitumor effects of chloroquine on oral squamous cell carcinoma. Mol. Med. Rep. 16(5), 5779-5786 (2017).|4. Grimaldi, A., Santini, D., Zappavigna, S., et al. Antagonistic effects of chloroquine on autophagy occurrence potentiate the anticancer effects of everolimus on renal cancer cells. Cancer Biol. Ther. 16(4), 567-579 (2015).|5. Jiang, P.-D., Zhao, Y.-L., Deng, X.-Q., et al. Antitumor and antimetastatic activities of chloroquine diphosphate in a murine model of breast cancer. Biomed. Pharmacother. 64(9), 609-614 (2010).