The Development and Scale-Up of an Antibody Drug Conjugate Tubulysin Payload

Significant development and scale-up work was completed on the synthesis of an antibody drug conjugate payload based on the tubulysin natural products. This work included the development of new routes to the tubuvaline and tubuphenylaniline portions of the molecules, as well as extensive optimization of the solid phase peptide synthesis used to assemble the molecule. The initial route (21 steps longest linear sequence, 0.01% overall yield) was improved to a new, more robust route (19 steps longest linear sequence, 2.4% overall yield) affording a 240-fold increase in overall yield and allowing delivery of over 86 g of the required molecule

Structure–Cytotoxicity Relationships of Analogues of <i>N</i>¹⁴-Desacetoxytubulysin H

Herein we report structure–cytotoxicity relationships for analogues of <i>N</i>¹⁴-desacetoxytubulyisn H <b>1</b>. A novel synthetic approach toward <b>1</b> enabled the discovery of compounds with a range of activity. Calculated basicity of the <i>N</i>-terminus of tubulysins was shown to be a good predictor of cytotoxicity. The impact of structural modifications at the C-terminus of <b>1</b> upon cytotoxicity is also described. These findings will facilitate the development of new tubulysin analogues for the treatment of cancer

Pyrimidinone Nicotinamide Mimetics as Selective Tankyrase and Wnt Pathway Inhibitors Suitable for in Vivo Pharmacology

The canonical Wnt pathway plays an important role in embryonic development, adult tissue homeostasis, and cancer. Germline mutations of several Wnt pathway components, such as Axin, APC, and ß-catenin, can lead to oncogenesis. Inhibition of the poly­(ADP-ribose) polymerase (PARP) catalytic domain of the tankyrases (TNKS1 and TNKS2) is known to inhibit the Wnt pathway via increased stabilization of Axin. In order to explore the consequences of tankyrase and Wnt pathway inhibition in preclinical models of cancer and its impact on normal tissue, we sought a small molecule inhibitor of TNKS1/2 with suitable physicochemical properties and pharmacokinetics for hypothesis testing in vivo. Starting from a 2-phenyl quinazolinone hit (compound <b>1</b>), we discovered the pyrrolopyrimidinone compound <b>25</b> (AZ6102), which is a potent TNKS1/2 inhibitor that has 100-fold selectivity against other PARP family enzymes and shows 5 nM Wnt pathway inhibition in DLD-1 cells. Moreover, compound <b>25</b> can be formulated well in a clinically relevant intravenous solution at 20 mg/mL, has demonstrated good pharmacokinetics in preclinical species, and shows low Caco2 efflux to avoid possible tumor resistance mechanisms