A decapeptide of the formula: N-Ac-A1-A2-A3-Ser-A4-A5-A6-A7-A8-A9, wherein each A1, A2, and A3, independently, is D- beta -Nal, D-p-X-Phe (where X is halogen, H, NH2, NO2, OH, or C1-3 alkyl), D-Trp, D-benzothienyl (2)-Ala, or D-benzothienyl (1)-Ala; A4 is p-X-Phe (where X is halogen, H, NH2, NO2, or C1-3 alkyl), Tyr, Lys, Arg, Leu, Trp, or Nal; A5 is D-Lys, D-Tyr, D-Arg, D-Phe, D- beta -Nal, D-Trp, D-homo-Arg, D-diethyl-homo-Arg, D-p-X-Phe (where X is halogen, H, NH2, NO2, or C1-3 alkyl), or D-Lys- epsilon -NH-R (where R is H, a branched or straight chain C1-C10 alkyl group, or an aryl group); A6 is Leu, beta -Nal, p-X-Phe (where X is halogen, H, NH2, NO2, OH, C2F5, C1-3 alkyl), or Trp; A7 is Arg, Lys, or Lys epsilon -NH-R (where R is H, a branched or straight chain C1-C6 alkyl group, or an aryl group); A8 is Pro; and A9 is D-Ala, D-Ala-NH2, Ala-NH2, aminoisobutyric acid amide, or Gly-NH2; provided that at least one of A2 or A3 must be D-Phe or D-Tyr, and provided further that when A4 is Lys or Arg, A5 must not be D-Arg, D-Lys, D-homo-Arg, D-diethyl-homo-Arg, or D-Lys- epsilon -NH-R, or a pharmaceutically acceptable salt thereof. The invention also features a method of treating T-cell-deficient patients, e.g., those suffering from Acquired Immune Deficiency Syndrome, by administering a therapeutically effective amount of an LH-RH antagonist.
Therapeutic decapeptides