LHRH ANTAGONISTS

2079461 9213883 PCTABS00014 Disclosed herein are analogues of the luteinizing hormone-releasing hormone (LH-RH), which are potent antagonists of LH-RH. These peptides inhibit the release of gonadrotropins from the pituitary in mammals, including humans and possess antitumor activity. Formula (I): X-R1-R2-R3-Ser-R5-R6(AY2)-Leu-Arg-Pro-D-Ala-NH2 represents peptides which are within the scope of this invention and the pharmaceutically acceptable salts thereof, wherein R1 is D-Phe, D-Phe(4Cl), D-Nal(1) or D-Nal(2), R2 is D-Phe or D-Phe(4Hl), R3 is D-Trp, D-Phe, D-Phe(4Hl), D-Nal(1), D-Nal(2) or D-Pal(3), R5 is Tyr or Arg, R6 is D-Lys or D-Orn, Hl is fluoro, chloro or bromo, X is a lower alkanoyl group of 2-5 carbon atoms, A is a diaminoacyl residue having formula (II), where m is 0 or 1, n is 0 or 1, Y is hydrogen or Y1 or Y2, wherein Y1 is an acyl group derived from straight or branched chain aliphatic, alicyclic carboxylic acids having from 3 to 12 carbon atoms or aromatic carboxylic acid of 6 or 10 ring carbon atoms, Y2 is carbamoyl or alkyl-substituted carbamoyl group having formula (III): H-(CH2)n-NH-CO-, where n is 0-3.