Antibody Fragment F(ab') 2 Targeting Caveolae-Associated Protein PV1 for Selective Kidney Targeting and Retention

Mol Pharm. 2020 Feb 3;17(2):507-516. doi: 10.1021/acs.molpharmaceut.9b00939. Epub 2019 Dec 30.

Abstract

Targeted strategies to deliver and retain drugs to kidneys are needed to improve drug accumulation and efficacy in a myriad of kidney diseases. These drug delivery systems show potential for improving the therapeutic windows of drugs acting in the kidney. Biodistribution of antibody-based therapeutics in vivo is governed by several factors including binding affinity, size, and valency. Investigations of how the biophysical and biochemical properties of biologics enable them to overcome biological barriers and reach kidneys are therefore of interest. Although renal accumulation of antibody fragments in cancer diagnostics and treatment has been observed, reports on effective delivery of antibody fragments to the kidneys remain scarce. Previously, we demonstrated that targeting plasmalemma vesicle-associated protein (PV1), a caveolae-associated protein, can promote accumulation of antibodies in both the lungs and the kidneys. Here, by fine-tuning the binding affinity of an antibody toward PV1, we observe that the anti-PV1 antibody with reduced binding affinity lost the capability for kidney targeting while retaining the lung targeting activity, suggesting that binding affinity is a critical factor for kidney targeting of the anti-PV1 antibody. We next use the antibody fragment F(ab')2 targeting PV1 to assess the dual effects of rapid kidney filtration and PV1 targeting on kidney-selective targeting. Ex vivo fluorescence imaging results demonstrated that after rapidly accumulating in kidneys at 4 h, PV1-targeted F(ab')2 was continually retained in the kidney at 24 h, whereas the isotype control F(ab')2 underwent urinary elimination with significantly reduced signaling in the kidney. Confocal imaging studies confirmed the localization of PV1-targeted F(ab')2 in the kidney. In addition, the monovalent antibody fragment (Fab-C4) lost the capability for kidney homing, indicating that the binding avidity of anti-PV1 F(ab')2 is important for kidney targeting. Our findings suggest that PV1-targeted F(ab')2 might be useful as a drug carrier for renal targeting and highlight the importance of affinity optimization for tissue targeting antibodies.

Keywords: PET/CT imaging; antibody fragment F(ab′)2; confocal imaging; ex vivo fluorescence imaging system; kidney targeting; plasmalemma vesicle-associated protein; targeted delivery.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Monoclonal / administration & dosage
  • Antibodies, Monoclonal / immunology*
  • Antibodies, Monoclonal / pharmacokinetics
  • Antibody Affinity
  • Caveolae / metabolism*
  • Drug Carriers / administration & dosage
  • Drug Carriers / pharmacokinetics*
  • Female
  • HEK293 Cells
  • Humans
  • Immunoglobulin Fab Fragments / administration & dosage
  • Immunoglobulin Fab Fragments / immunology*
  • Kidney / drug effects*
  • Kidney / metabolism
  • Lung / drug effects
  • Lung / metabolism
  • Membrane Proteins / immunology*
  • Mice
  • Mice, Inbred BALB C
  • Tissue Distribution

Substances

  • Antibodies, Monoclonal
  • Drug Carriers
  • Immunoglobulin Fab Fragments
  • Membrane Proteins
  • PLVAP protein, human