Novel Selective Estrogen Receptor Ligand Conjugates Incorporating Endoxifen-Combretastatin and Cyclofenil-Combretastatin Hybrid Scaffolds: Synthesis and Biochemical Evaluation Nuclear receptors such as the estrogen receptors (ERα and ERβ) modulate the effects of the estrogen hormones and are important targets for design of innovative chemotherapeutic agents for diseases such as breast cancer and osteoporosis. Conjugate and bifunctional compounds which incorporate an ER ligand offer a useful method of delivering cytotoxic drugs to tissue sites such as breast cancers which express ERs. A series of novel conjugate molecules incorporating both the ER ligands endoxifen and cyclofenil-endoxifen hybrids covalently linked to the antimitotic and tubulin targeting agent combretastatin A-4 were synthesised