Specially designed non-mammalian GnRH analogs resistant to degradation by the
tumor tissue enzymes, post-
proline peptidases as well as endopeptidases, are disclosed. The GnRH analogs are further defined as analogs of chicken II GnRH, salmon GnRH, or
herring GnRH, but can include any non-mammalian GnRH analog with similar
amino acid structure. These non-mammalian analogs incorporate D-
arginine, D-
leucine, D-tBu-
Serine or D-Trp or other similar amino acids at position 6 and ethylamide or aza-Gly-
amide or similar amides at position 10. These analogs demonstrate preferential binding to tumor
cell GnRH receptors that is greater relative to the binding of the mammalian analogs to the tumor
cell GnRH receptor. These non-mammalian GnRH analogs may be used in pharmaceutical preparations, and it specifically in various treatments as an anti-tumor, anti-proliferation, anti-metastatic and / or an apoptotic agent. The non-mammalian GnRH analogs are also provided in pharmaceutical preparations that may be used clinically for
tumor regression when used in very low doses and administered in pulsatile fashion.