# Quantification of endogenous and therapeutic IgG crossing the kidney barrier from bloodstream to urine

## TL;DR

This study shows how a therapeutic antibody, rituximab, moves from the blood to urine through the kidney, similar to natural antibodies.

## Contribution

The study quantifies the predictable pharmacokinetic profile of therapeutic IgG1 in urine relative to serum.

## Key findings

- Rituximab's urinary concentration correlates with its serum levels.
- Therapeutic IgG1 crosses the kidney barrier similarly to endogenous IgG.
- Findings support optimal dosing for urothelium-targeting antibodies.

## Abstract

This study investigates the biodistribution of a therapeutic antibody from serum to urine across the kidney endothelial barrier, contextualizing the findings with existing literature. Our analysis shows the quantitative correlation between serum levels of the intravenously administered antibody rituximab and its urinary concentration, indicating a predictable pharmacokinetic profile. The results align with previous quantitative studies on the biodistribution of endogenous and vaccination induced IgG between serum and urine, confirming that recombinant therapeutic IgG1 passes the kidney endothelial barrier and exhibits similar biodistribution to endogenous IgG. These insights may inform the determination of optimal dosages for therapeutic antibodies targeting the urothelium or renal epithelium.