Improved Lysosomal Trafficking Can Modulate the Potency of Antibody Drug Conjugates

Abstract

Antibody drug conjugates (ADCs) provide an efficacious and relatively safe means by which chemotherapeutic agents can be specifically targeted to cancer cells. In addition to the selection of antibody targets, ADCs offer a modular design that allows selection of ADC characteristics through the choice of linker chemistries, toxins, and conjugation sites. Many studies have indicated that release of toxins bound to antibodies via noncleavable linker chemistries relies on the internalization and intracellular trafficking of the ADC. While this can make noncleavable ADCs more stable in the serum, it can also result in lower efficacy when their respective targets are not internalized efficiently or are recycled back to the cell surface following internalization. Here, we show that a lysosomally targeted ADC against the protein APLP2 mediates cell killing, both in vitro and in vivo, more effectively than an ADC against Trop2, a protein with less efficient lysosomal targeting. We also engineered a bispecific ADC with one arm targeting HER2 for the purpose of directing the ADC to tumors, and the other arm targeting APLP2, whose purpose is to direct the ADC to lysosomes for toxin release. This proof-of-concept bispecific ADC demonstrates that this technology can be used to shift the intracellular trafficking of a constitutively recycled target by directing one arm of the antibody against a lysosomally delivered protein. Our data also show limitations of this approach and potential future directions for development.

Manipulation of Cell-Type Selective Antibody Internalization by a Guide-Effector Bispecific Design

“…There are a few recent reports of bispecific ADC with the internalizing arm binding to either a lysosomal protein or an antigen that rapidly traffics to the lysosome (5)(6)(7). In most cases, the observation is empirical and the bispecific effect is rather moderate, suggesting that key parameters affecting bispecific-induced internalization have not been fully delineated.…”

“…For example, through the biparatopic design and the consequent cross-linking effect, HER2 antigen has been targeted for improved ADC internalization (4). In another example, a bispecific composed of a moderately internalizing antibody arm (anti-HER2) and an internalization-inducing antibody arm (anti-CD63, anti-PRLR, or anti-APLP2) was constructed and used to improve ADC uptake (5)(6)(7). However, despite those efforts, the bispecific ADC only showed limited improvement over the parental monospecific anti-HER2 ADC, suggesting that key parameters regarding this design remains to be delineated.…”

A novel enediyne‐integrated antibody–drug conjugate shows promising antitumor efficacy against CD30+ lymphomas

“…Furthermore, research had demonstrated that ADCs with a payload conjugated to the light chain of the mAb were shown to perform significantly higher in vivo efficacy compared with those conjugated to the heavy chain (Shen et al ., ). On the other hand, noncleavable linkers are intended to be more stable in the bloodstream and extracellular space, because ADCs release their toxins relying on the internalization and lysosomal degradation (DeVay et al ., ; Peters and Brown, ; Ritchie et al ., ). Therefore, ADC efficacy depends in part on antibody–antigen interaction at the cell surface triggering the internalization and lysosomal trafficking.…”

Bispecifics and antibody–drug conjugates: A positive synergy

“…Interestingly, whilst demonstrating the potential of such a "drag and degradation" approach, DeVay et al noted limitations to this strategy [36]. A model bispecific ADC with a HER2 arm and an Amyloid Precursor Like Protein 2 (APLP2) arm was prepared.…”