Molecular insights into dimerization inhibition of c-Maf transcription factor

The Maf protein family belongs to the activator protein 1 (AP-1) superfamily of transcription factors that bind specific DNA target sequences through a basic region and exploit a leucine zipper (LZ) motif for protein-protein interactions leading to homo- or hetero-dimerization. Mafs unique DNA-binding domain contains a highly conserved extended homology region (EHR) that allows to recognize longer DNA sequences than other basic leucine zipper (bZIP) transcription factors. Inspired by the fact that overexpression of Mafs is observed in about 50% of cases of multiple myeloma, a hematological malignant disorder, we undertook a peptide inhibitor approach. The LZ domain of c-Maf, one of large Mafs, was produced by solid phase peptide synthesis. We characterized its secondary structure and dimerization properties, and found that dimerization and folding events are strictly coupled. Moreover, potential peptidic c-Maf dimerization inhibitors were computationally designed and synthesized. These compounds were demonstrated by circular dichroism (CD) spectroscopy and MALDI-TOF mass spectrometry to bind to c-Maf LZ monomers, to drive folding of their partially disordered structure and to efficiently compete with dimerization, suggesting a way for interfering with the function of c-Maf and, more generally, of intrinsically disordered proteins, till now considered undruggable targets.

Pertuzumab for the treatment of breast cancer

HER2-targeted therapies have revolutionized the outcome of patients with HER2-positive breast cancer. Pertuzumab is the first in a new class of monoclonal antibodies that target the extracellular dimerization domain of HER2 receptors, also known as HER dimerization inhibitors. The development of pertuzumab and preclinical and clinical data in breast cancer are reviewed. Regulatory affairs related to pertuzumab and the recent accelerated approval granted by the FDA for the treatment of breast cancer in the neoadjuvant setting are also covered. This process opens doors for further approvals which could considerably shorten the time between initial drug development and availability.