Heregulin antagonists and methods for their use

A therapeutic method to inhibit cancer cell growth comprising administering to a mammal (i.e. a human) in need of such therapy, an amount of a compound of formula (I):

• ##STR17## wherein R.sub.1 is OH or --CH.sub.2 C(O)N((C.sub.1 -C.sub.4)alkyl).sub.2 ;
• R.sub.2 is --CH.dbd.N--N(R.sub.7)(R.sub.8), --CH.dbd.NO((C.sub.1 -C.sub.12)alkyl), --CH.dbd.NOCH(phenyl).sub.2, --CH.dbd.NO(CH.sub.2).sub.n -phenyl, --CH.dbd.N--NHR.sub.9, --CH.dbd.N--R.sub.10 ##STR18## n is 1-6;
• R.sub.3 and R.sub.4 are each independently H, (C.sub.1 -C.sub.4)alkyl, halo, halo(C.sub.1 -C.sub.4)alkyl, or (C.sub.5 -C.sub.7)aryl optionally comprising 1-2 N, S or non-peroxide O and optionally substituted with (C.sub.1 -C.sub.4)alkyl or halo;
• R.sub.5 and R.sub.6 are each independently H, OH, --NH.sub.2, --C(O)OH or --C(O)NH.sub.2 ;
• R.sub.7 is H or (C.sub.1 -C.sub.4)alkyl;
• and R.sub.8 is a bi- or tricyclic ring, said ring comprising 7 to 10 carbons, optionally comprising one or more heteroatoms selected from S, N or non-peroxide O, said ring optionally substituted with (C.sub.1 -.sub.4)alkyl, halo or halo(C.sub.1 -C.sub.4)alkyl;
• or R.sub.7 and R.sub.8 together with the nitrogen to which they are attached form a ring comprising 10 to 20 carbons, optionally comprising one or more heteroatoms selected from S, N or non-peroxide O, said ring optionally substituted with (C.sub.1 -C.sub.4)alkyl, halo or halo(C.sub.1 -C.sub.4)alkyl;
• R.sub.9 is (C.sub.1 -C.sub.4)alkyl, a peptidyl residue of naturally occuring amino acid, or a di-, tri-, or tetra-peptide;
• and
• R.sub.10 is a a piperazin-1-yl ring, optionally substituted on carbon with one or two substituents selected from the values defined for R.sub.3 and R.sub.4, and optionally substituted at the 4-position with a group R.sub.11, wherein R.sub.11 is (C.sub.1 -C.sub.4)alkyl, phenyl, benzyl, a peptidal residue of a naturally occuring amino acid, or a di-, tri-, or tetra-peptide;
• or a pharmaceutically acceptable salt thereof;
• wherein said amount is effective to inhibit growth of said cancer cells.