Summary p97 is a AAA-ATPase with multiple cellular functions, one of which is critical regulation of protein homeostasis pathways. We describe the characterization of CB-5083, a potent, selective and orally bioavailable inhibitor of p97. Treatment of tumor cells with CB-5083 leads to accumulation of poly-ubiquitinated proteins, retention of endoplasmic reticulum associated degradation (ERAD) substrates and generation of irresolvable proteotoxic stress leading to activation of the apoptotic arm of the unfolded protein response (UPR). In xenograft models, CB-5083 causes modulation of key p97-related pathways, induces apoptosis and has antitumor activity in a broad range of both hematological and solid tumor models. Molecular determinants of CB-5083 activity include expression of genes in the ERAD pathway providing a potential strategy for patient selection.

No abstract

The AAA-ATPase p97 plays vital roles in mechanisms of protein homeostasis, including ubiquitin-proteasome system (UPS) mediated protein degradation, endoplasmic reticulum-associated degradation (ERAD), and autophagy. Herein we describe our lead optimization efforts focused on in vitro potency, ADME, and pharmaceutical properties that led to the discovery of a potent, ATP-competitive, D2-selective, and orally bioavailable p97 inhibitor 71, CB-5083. Treatment of tumor cells with 71 leads to significant accumulation of markers associated with inhibition of UPS and ERAD functions, which induces irresolvable proteotoxic stress and cell death. In tumor bearing mice, oral administration of 71 causes rapid accumulation of markers of the unfolded protein response (UPR) and subsequently induces apoptosis leading to sustained antitumor activity in in vivo xenograft models of both solid and hematological tumors. 71 has been taken into phase 1 clinical trials in patients with multiple myeloma and solid tumors.

Pregabalin exhibits robust activity in preclinical assays indicative of potential antiepileptic, anxiolytic, and antihyperalgesic clinical efficacy. It binds with high affinity to the alpha(2)-delta subunit of voltage-gated calcium channels and is a substrate of the system L neutral amino acid transporter. A series of pregabalin analogues were prepared and evaluated for their alpha(2)-delta binding affinity as demonstrated by their ability to inhibit binding of [(3)H]gabapentin to pig brain membranes and for their potency to inhibit the uptake of [(3)H]leucine into CHO cells, a measure of their ability to compete with the endogenous substrate at the system L transporter. Compounds were also assessed in vivo for their ability to promote anxiolytic, analgesic, and anticonvulsant actions. These studies suggest that distinct structure activity relationships exist for alpha(2)-delta binding and system L transport inhibition. However, both interactions appear to play an important role in the in vivo profile of these compounds.

No abstract