brequinar brequinar brequinar (dup-785) is a drug that acts as a potent and selective inhibitor of the enzyme dihydroorotate dehydrogenase. it blocks synthesis of pyrimidine based nucleotides in the body and so inhibits cell growth. brequinar was invented by dupont pharmaceuticals in the 1980s. in 2001, bristol-myers squibb acquired dupont, and in 2017, clear creek bio acquired the rights to brequinar from bms. brequinarclinical datatrade namesbrequinaridentifiers iupac name 6-fluoro-2-(2'-fluoro-1,1'-biphenyl-4-yl)-3-methyl-4-quinolinecarboxylic acid cas number96187-53-0pubchem cid57030drugbankdb03523chemspider51422unii5xl19f49h6keggd03154chebichebi:177387chemblchembl38434comptox dashboard (epa)dtxsid00242165 chemical and physical dataformulac23h15f2no2molar mass375.4 g·mol−13d model (jsmol)interactive image smiles cc1=c(c2=c(c=cc(=c2)f)n=c1c3=cc=c(c=c3)c4=cc=cc=c4f)c(=o)o inchi inchi=1s/c23h15f2no2/c1-13-21(23(27)28)18-12-16(24)10-11-20(18)26-22(13)15-8-6-14(7-9-15)17-4-2-3-5-19(17)25/h2-12h,1h3,(h,27,28)key:phezjeyuwhetko-uhfffaoysa-n brequinar has been investigated as an immunosuppressant for preventing rejection after organ transplant and also as an anti-cancer drug, but was not accepted for medical use in either application largely due to its narrow therapeutic dose range and severe side effects when dosed inappropriately. it has been researched both as part of a potential combination therapy for some cancers, or alternatively as an antiparasitic, or antiviral drug. clear creek bio is currently developing brequinar as a potential treatment for covid-19. inhibition of dihydroorotate dehydrogenase activity by brequinar may represent an efficient approach to the elimination of undifferentiated cells for safe psc‐derived differentiated cells based therapies.