MCT4-IN-1 is an orally active and selective monocarboxylate transporter 4 (MCT4/SLC16A3) inhibitor with an IC50 of 77 nM and a Ki of 11 nM. MCT4-IN-1 targets to the cytosolic domain of MCT4. MCT4-IN-1 results in lactate efflux inhibition and reduction of cellular viability in MCT4 high expressing cells. MCT4-IN-1 has the potential for MCT4 transporter inhibition research[1].

MCT4-IN-1 (compound 18n) inhibits lactate efflux in the MDA-MB-231 cell line with an IC50 of 1 nM. The on-target activity is confirmed with a Ki of 11 nM by fluorescence cross-correlation spectroscopy (FCCS)[1]. MCT4-IN-1 does not inhibit lactate efflux to a similar extent in SNU-398 and MiaPaca2, and only 600-fold less in RT-4 cell lines[1].

MCT4-IN-1 (compound 18n; 30 mg/kg; PO; single dose) only combined with MCT1/2 inhibitor exhibits a significant tumoral intracellular lactate accumulation[1]. MCT4-IN-1 (30 mg/kg/day; for 15 days) shows no significant antitumor activity[1]. MCT4-IN-1 (0.2 mg/kg; iv) has a T1/2 of 1 hours, a CL of 0.33 L/h•kg, a Cmax of 489 ng/mL and a Vss of 0.4 L/kg for mice[1].

[1]. Timo Heinrich, et al. Discovery of 5-{2-[5-Chloro-2-(5-ethoxyquinoline-8-sulfonamido)phenyl]ethynyl}-4-methoxypyridine-2-carboxylic Acid, a Highly Selective in Vivo Useable Chemical Probe to Dissect MCT4 Biology. J Med Chem. 2021 Aug 26;64(16):11904-11933.