A conjugate of formula: V--(Y).sub.a-Z-T (I), T-X--B--(Y).sub.a-Z-T' (II), V--(Y).sub.a-Z-(Y').sub.a--V' (III), T-X--B--(Y).sub.a-Z-(Y').sub.a--X'--B'-T' (IV), V--(Y).sub.a-Z-(Y').sub.a--X--B-T (V), V--(Y).sub.a-Z-X--B-Z'-(Y').sub.a--(V').sub.b (VI), or (W).sub.a--(Y).sub.b-[(Z).sub.c-(Y').sub.d--(X--B).sub.e--(Y'').sub.f-(Z')- .sub.g].sub.h-(Y''').sub.i--(W').sub.j (VII), in which W and W' are independently a DNA intercalator or terminal subunit, V and V' are independently a DNA intercalator, X and X' are independently a DNA alkylator, B and B' are the same or different and each is a heteroaromatic residue that is attached to the N-terminus of an alkylator subunit (X or X'), Y, Y', Y'' and Y''' are independently a linker, T and T' are independently terminal subunits, Z and Z' are independently a polyamide group that binds to the minor groove of DNA, a, b, c, d, f, g, i, and j are independently 0 to 5, and e and h are independently 1 to 5, a composition comprising a conjugate of any of formulae (I)-(VII) and a carrier, and a method for treating cancer in a mammal comprising administering an effective amount of a conjugate of any of formulae (I)-(VII) or a composition comprising same.