Novel Phosphate Modified Cathepsin B Linkers: Improving Aqueous Solubility and Enhancing Payload Scope of ADCs

Abstract

In an effort to examine the utility of antibody-drug conjugates (ADCs) beyond oncology indications, a novel phosphate bridged Cathepsin B sensitive linker was developed to enable the targeted delivery of glucocorticoids. Phosphate bridging of the Cathepsin B sensitive linkers allows for payload attachment at an aliphatic alcohol. As small molecule drug-linkers, these aqueous soluble phosphate containing drug-linkers were found to have robust plasma stability coupled with rapid release of payload in a lysosomal environment. Site-specific ADCs were successfully made between these drug-linkers and an antibody against human CD70, a receptor specifically expressed in immune cells but also found aberrantly expressed in multiple human carcinomas. These ADCs demonstrated in vitro targeted delivery of glucocorticoids to a representative cell line as measured by changes in glucocorticoid receptor (GR) mediated gene mRNA levels. This novel linker expands the scope of potential ADC payloads by allowing an aliphatic alcohol to be a stable, yet cleavable attachment site. This phosphate linker may have broad utility for internalizing ADCs as well as other targeted delivery platforms.

The Role of Organic Synthesis in the Emergence and Development of Antibody–Drug Conjugates as Targeted Cancer Therapies

“…Encouragingly,t his ADC exhibited binding to its target as measured mRNAe xpression in ac ell-based assay thereby demonstrating its potential to improve the performance of the budesonide drug. [128] We predict that this paradigm will continue to grow in importance and scope as the drive toward more precision medicines devoid of serious sideeffects for patients intensifies.Arecently published book (2018) [129] provides more details of updates and previews of recent developments,a nd others yet to come,i nt he ADC area to address av ariety of medical indications.…”

Die Bedeutung der organischen Synthese bei der Entstehung und Entwicklung von Antikörper‐Wirkstoff‐Konjugaten als gezielte Krebstherapien

“…Das Anti‐αCD70‐Budesonid‐Konjugat ( 332 , Abbildung ) wurde aus einem Anti‐αCD70‐Antikörper hergestellt, indem ein kortikosteroider entzündungshemmender Wirkstoff (wenn auch mit unangenehmen Nebenwirkungen bei Verabreichung als Einzelpräparat) durch einen neuartigen Phosphat‐Valin‐Citrullin‐Linker angebracht wurde, um seine unerwünschten Nebenwirkungen zu beseitigen. Ermutigenderweise zeigte dieses ADC die Bindung an sein Ziel, wie die in einem zellbasierten Assay gemessene mRNA‐Expression zeigte und demonstrierte damit sein Potenzial zur Effizienzverbesserung von Budesonid als Medikament . Wir gehen davon aus, dass dieses Paradigma weiter an Bedeutung und Umfang gewinnen wird, da sich der Trend zu präziseren Medikamenten zur Vermeidung schwerwiegende Nebenwirkungen für Patienten verstärkt.…”

“…B. isolierte Ketogruppen oder Azidsubstituenten), die selektiv mit einer reziproken Einheit aus dem Linker‐Wirkstoff adressiert werden können (vgl. Konjugat 331 , Abbildung und Abbildung E) …”

Innovative Linker Strategies for Tumor‐Targeted Drug Conjugates

“…Moreover,t his design resulted in high plasma stability,w hile the release of free budesonide in rat lysosomal lysates was confirmed:u ponl inker cleavage mediated by cathepsin B, phosphatases efficiently release the free drugf rom phosphate metabolite 39.E fficacy was confirmed by activity assays in vitro, as the linker-drug module incorporated in an ADC structure promoted the expression of GILZ protein (glucocorticoidinducedl eucine zipper) in antigen-positive 786-O cells, as determined by RT-PCR. [76] In summary,t he large amounto fr ecent literaturer eports on chemical connectionsb etweend rugs and Figure 4. Evolution of PAB-based self-immolative spacers from the proteasepromoted releaseofp ayloads bearing secondaryamine (e.g.…”