Development of Anti-CD74 Antibody–Drug Conjugates to Target Glucocorticoids to Immune Cells

Abstract

Glucocorticoids (GCs) are excellent anti-inflammatory drugs but are dose-limited by on-target toxicity. We sought to solve this problem by delivering GCs to immune cells with antibody-drug conjugates (ADCs) using antibodies containing site-specific incorporation of a non-natural amino acid, novel linker chemistry for in vitro and in vivo stability, and existing and novel glucocorticoid receptor (GR) agonists as payloads. We directed fluticasone propionate to human antigen-presenting immune cells to afford GR activation that was dependent on the targeted antigen. However, mechanism of action studies pointed to accumulation of free payload in the tissue culture supernatant as the dominant driver of activity and indeed administration of the ADC to human CD74 transgenic mice failed to activate GR target genes in splenic B cells. Suspecting dissipation of released payload, we designed an ADC bearing a novel GR agonist payload with reduced permeability which afforded cell-intrinsic activity in human B cells. Our work shows that antibody-targeting offers significant potential for rescuing existing and new dose-limited drugs outside the field of oncology.

Antibody Conjugates-Recent Advances and Future Innovations

“…cleavage (Figure 7) [51]. In this study, the fluticasone propionate derived payload has a high intrinsic binding affinity to target, but also bears a charged phosphate moiety.…”

“…Linker-payload design is critical in modulating bystander effect of payloads. A diphosphatase-cleavable linker has been reported for the selective delivery of immune suppressing payloads to immune cells following ADC internalization and diphosphate cleavage ( Figure 7) [51]. In this study, the fluticasone propionate derived payload has a high intrinsic binding affinity to target, but also bears a charged phosphate moiety.…”

“…Genentech has pioneered antibody-antibiotic conjugates [41,42] to target intracellular Staphylococcus aureus within host cells. Others have leveraged the internalization mechanism of antibodies to deliver immunosuppressive, cardiovascular or metabolic disorder small molecule drugs to specific cells using cell surface targets such as E-selectin [43], CD11a [44,45], CD25 [46], a3(IV)NC1 [47], CXCR4 [40,48], CD45 [49], CD70 [50], CD74 [51], and CD163 [52,53]. Examples of linker payloads as well as formulation and delivery challenges for non-oncology indications are discussed below.…”

“…Expanding on these preliminary experiments, an anti-CD163 conjugate was used to deliver dexamethasone to macrophages showing a synergistic anti-inflammatory effect of the conjugate versus its components alone, and a significant reduction in the systemic steroidal side-effects of orally dosed dexamethasone at the same efficacy [52]. Known glucocorticoid receptor (GR) agonists (i.e., dexamethasone j, budesonide k, and fluticasone propionate l) have also been attached to anti-CD74, anti-CD70, and anti-CD25 antibodies showing an immune cell targeted anti-inflammatory response, as well as highlighting the complexities of developing ADCs in this therapeutic area [46,50,51,106]. This novel modality promises treatment to larger populations of patients with autoimmune disorders, in a disease specific fashion that could potentially replace traditional steroid treatments as the standard of care.…”

Innovative Linker Strategies for Tumor‐Targeted Drug Conjugates

“…[5] Noteworthy,w hilethis research field has historically found widespread application in oncology (due to the medical need for potent cytotoxic agentsw ith improvedt herapeutic indexes), the preparation of targeted formulations and conjugatesh as also been recently proposed for other illnesses, such as bacterial infections, [6] osteoporosis, [7] bone fractures, [8] rheumatoid arthritis, [9] and other inflammatory diseases. [10] Among the structuralc omponents of tumor-targetingd evices, the carrier is the key regulator of the pharmacokinetic properties, since its size and structural features modulate the circulatory half-life,e xtravasationr ates, and residence time in the tumor ande xcretion. Nanosized materials such as engineeredt herapeutic nanoparticles, [11] and polymer-drug conjugates (PDCs) [12] often show ap referential accumulationi n Figure 1.…”