Targeted Drug Delivery Using a Plug-to-Direct Antibody–Nanogel Conjugate

Abstract

Targeted drug delivery using antibody–drug conjugates has attracted great attention due to its enhanced therapeutic efficacy compared to traditional chemotherapy. However, the development has been limited due to a low drug-to-antibody ratio and laborious linker-payload optimization. Herein, we present a simple and efficient strategy to combine the favorable features of polymeric nanocarriers with antibodies to generate an antibody–nanogel conjugate (ANC) platform for targeted delivery of cytotoxic agents. Our nanogels stably encapsulate several chemotherapeutic agents with a wide range of mechanisms of action and solubility. We showcase the targetability of ANCs and their selective killing of cancer cells over-expressing disease-relevant antigens such as human epidermal growth factor receptor 2, epidermal growth factor receptor, and tumor-specific mucin 1, which cover a broad range of breast cancer cell types while maintaining low to no toxicity to non-targeted cells. Overall, our system represents a versatile approach that could impact next-generation nanomedicine in antibody-targeted therapeutics.

Optimizing Conjugation Chemistry, Antibody Conjugation Site, and Surface Density in Antibody–Nanogel Conjugates (ANCs) for Cell-Specific Drug Delivery

“…The resulting polymer was characterized by the comparison of spectra with the literature. 14 Polymers P1, P2, and P4 Were Prepared in Two Steps. (1) Boc deprotection to obtain P0: 200 mg of Bocprotected BCP was dissolved in a mixture of 1 mL of DCM and 1 mL of TFA and stirred for 5 min at 0 °C.…”

“…The precipitate was collected and dried under vacuum. The resulting polymer was characterized by the comparison of spectra with the literature …”

“…The polymeric nanogels were prepared according to a previously published procedure. 14 A 1:1 (wt) mixture of P1 or P2 (polymers with Ab-conjugation handles) and P3 (OMe-terminal polymer) was utilized to produce the nanogels. Briefly, P1, P2, and P3 were freshly prepared at 50 mg/mL in DMSO.…”

“…10−12 Compared to ADCs and these antibody−polymer conjugates (APCs), antibody−nanogel conjugates (ANCs) offer an excellent option to conveniently improve the DAR by 10 2 −10 5 times. 13,14 In addition to significantly increasing drug exposure to the tumor site due to the high DAR, ANCs prevent the premature release of the payload because of the enhanced drug stability within nanogel formulations. 15−19 However, for ANCs to be a clinically realistic platform, antibody conjugation efficiency and batch-to-batch consistency must be substantially improved.…”

“…Small-molecule-based targeting ligands such as folic acid or peptides can be efficiently conjugated to polymer backbones or nanoparticles for the precise control of surface ligand density and high batch-to-batch consistency. , Due to the limited stability of proteins and antibodies in organic solvents, ANCs are typically constructed through postformulation conjugation chemistries such as thiol–maleimide chemistry, 1-ethyl-3-(3-(dimethylamino)­propyl)­carbodiimide (EDC) coupling, and strain-promoted alkyne–azide cycloadditions (SPAACs). , SPAAC between dibenzocyclooctyne (DBCO) and azide (N 3 ) is preferably used in most of the ANC constructs due to its robust conjugate stability and mild reaction conditions. ,,− However, considering that the low k 2 value of SPAAC for small molecules is ∼0.1 M –1 s –1 , conjugation kinetics between antibodies and nanogels with significantly higher molecular weights would be even slower . Indeed, ANC preparation using SPAACs typically requires long conjugation times (>24 h at 4 °C) and the associated inefficiency demands an additional purification step to remove unconjugated antibodies, , which further increase difficulties in quality control, optimizations, and characterizations.…”