Design, synthesis and optimization of nucleotide-derived inhibitors and probes for the ecto-nucleotidases CD39 and CD73

Abstract

Cell damage or cell lysis as a consequence of organ injury, shock, or inflammtory conditions leads to a massive release of intracellular ATP. ATP activates purinergic P2Y and P2X cell membrane receptors. ATP signaling is stopped by its hydrolysis to adenosine by ecto-nucleotidases, in particular by nucleoside triphosphate diphosphohydrolase1 (CD39) and ecto- 5'-nucleotidase (CD73). Adenosine exerts anti-inflammatory, immunosuppressive, tumor growth-stimulating, and angiogenic effects by activating G protein-coupled adenosine receptors. Therefore, inhibitors of CD39 and CD73 possess great potential as novel drugs for the (immuno)therapy of cancer and infections. <br /> The first objective of this thesis was to identify potent, selective, and metabolically stable inhibitors for CD39 based on the lead structures of 8-BuS-AMP and ARL67156. Analogs were synthesized and structure-activity relationships (SARs) were analyzed. <br /> The second objective of this thesis was to synthesize and develop various tool compounds for CD73 and to investigate a new class of CD 73 inhibitors. In the past, potent, selective and metabolically stable nucleotide-based inhibitors for CD73 had been developed. To provide those compounds to collaborators for extended studies, large amounts have to be obtained. Therefore the synthetic route towards 2-chloro-N6-substituted AOPCP derivatives was optimized and two AOPCP derivatives, PSB-12379 and PSB-12489, were synthesized on a large scale (>100 mg). <br /> To allow further investigation of CD73 as a potential drug target, tool compounds were designed and synthesized including a tritium-labeled radioligand, fluorescent probes, and a potential tracer for positron emission tomography. Moreover, a new class of CD73 inhibitors was investigated based on the structure of 7-deaza-AOPCP. The CD73-inhibitory potency, however, was significantly decreased upon replacing the nitrogen at the 7-position by carbon. <br /> With this work, we have been able to significantly advance the development of new CD39 and CD73 inhibitors and probes, which will be useful to further explore their potential as drug targets for the immunotherapy of cancer or in the context of inflammatory diseases.