The technology is a set of ligand dimers, comprised of two ligands and a linker with a coiled coil domain. The dimer can bind with higher affinity to HER receptors, and subsequently cause selective homo- and hetero- dimerization, oligomerization, or aggregation of these receptors. The ligand dimers modulate interactions between these receptors, thus biasing or inhibiting downstream signaling transduction. For example, the neuregulin-1β (NRG1) homodimer has high affinity for the HER4/ErbB4 receptor and promotes HER4 homodimerization on cardiomyocytes. This leads to initiation of the PI3 kinase signaling cascade which plays a prominent role in cell survival, and, more specifically, in the cardiomyocyte response to toxic stimulus. This technology exhibits greater control with these selective abilities and provides a safer, more effective, and more cardioprotective addition to anticancer therapy treatment.