Becotatug vedotin

Targeted payload delivery strategies, such as antibody‐drug conjugates (ADCs), have emerged as important therapeutics. Although considerable efforts have been made in the areas of antibody engineering and labeling methodology, improving the overall physicochemical properties of the linker/payload combination remains an important challenge. Here we report an approach to create an intrinsically hydrophilic linker domain. We find that benzyl α‐ammonium carbamates (BACs) undergo tandem 1,6–1,2‐elimination to release secondary amines. Using a fluorogenic hemicyanine as a model payload component, we show that a zwitterionic BAC linker improves labeling efficiency and reduces antibody aggregation when compared to a commonly used para‐amino benzyl (PAB) linker as well as a cationic BAC. Cellular and in vivo fluorescence imaging studies demonstrate that the model payload is specifically released in antigen‐expressing cells and tumors. The therapeutic potential of the BAC linker strategy was assessed using an MMAE payload, a potent microtubule‐disrupting agent frequently used for ADC applications. The BAC‐MMAE combination enhances labeling efficiency and cellular toxicity when compared to the routinely used PAB‐Val‐Cit ADC analogue. Broadly, this strategy provides a general approach to mask payload hydrophobicity and improve the properties of targeted agents.

Antibody-drug conjugates (ADCs) have advanced as a mainstay among the most promising cancer therapeutics, offering enhanced antigen targeting and encompassing wide diversity in their linker and payload components. Small-molecule inhibitors of tubulin polymerization have found success as payloads in FDA approved ADCs and represent further promise in next-generation, pre-clinical and developmental ADCs. Unique dual-mechanism payloads (previously designed and synthesized in our laboratories) function as both potent antiproliferative agents and promising vascular disrupting agents capable of imparting selective and effective damage to tumor-associated microvessels. These payloads have been incorporated into a variety of drug-linker constructs utilizing the clinically relevant cathepsin B cleavable Val-Cit dipeptide linker, employed within several FDA approved ADCs, along with other non-cleavable constructs. Various synthetic strategies were evaluated to prepare these drug-linker constructs. Aniline-based payloads were incorporated utilizing the Val-Cit dipeptide linker similar to FDA approved ADCs such as Adcetris^® (brentuximab vedotin). An additional self-immolative group, previously described in the literature for related model systems, was employed to tether the phenolic payloads. A variety of drug-linker constructs (with each bearing a unique dual mechanism payload) were synthesized and evaluated biologically for their enzyme-mediated release of payload and inhibition of tubulin polymerization. Following deactivation of the highly electrophilic maleimido terminus as its corresponding N-acetyl cysteine (NAC) derivative, the most promising construct (NAC-4) demonstrated approximately 90% release of an aniline-functionalized payload (1) upon treatment with cathepsins B or L over 90 minutes. Building on these promising results, future studies will examine the conjugation of drug-linker construct 4 to selected antibodies and engineered proteins and evaluate the biological activity of the resultant antibody-drug conjugates (ADCs).