A chimeric ErbB ligand binding molecule is disclosed along with its pharmaceutically acceptable salt forms. The molecule is a protein that as part of its sequence includes the sequence of SEQ ID NOS: 1, 2, or 3. The molecule can be fused to an IgGFc and especially IgGFc containing cysteine to serine changes in the hinge region. For example, the fusion can be to IgG 1Fc DNA sequences that encode the binding molecules are also contemplated as well as vectors containing such DNA sequences and hosts that contain such vectors. Pharmaceutical compositions are contemplated that contain the binding molecule along with a pharmaceutically acceptable excipient.
