Abstract
This study explores the impact of antibody surface charge on tissue distribution into various tissues including tumor. Tumor-bearing mice were dosed intravenously with a mixture comprising three antibodies engineered to carry negative charge patches, a balanced charge distribution, or positive patches, respectively (cassette dosing). Tissue levels were analyzed with a specific LC-MS/MS method. In addition, the antibody mix was administered to non-tumor bearing mice. Muscle and skin interstitial fluid were obtained by centrifugation and analyzed by LC-MS/MS. An in vitro endothelium model was explored for its feasibility to mimic the observed distribution differences.A balanced charge distribution was optimal in terms of total tumor exposure, while in other tissues, negatively charged and balanced charged antibodies gave similar results. In contrast, positive charge patches generally resulted in increased serum clearance but markedly enhanced tumor and organ uptake, leading to higher tissue-to-serum ratios. The uptake and availability in the interstitial space were confirmed by specific assessment of antibody levels in the interstitial fluid of the muscle and skin, with similar charge impact as in total tissue. The in vitro model was able to differentiate the transport propensity of this series of antibody variants. In summary, our results show the differential effects of charge patches on an antibody surface on biodistribution and tumor uptake. These insights may help in the design of molecules with biodistribution properties tailored to their purpose, and an optimized safety profile.
Highlights
Monoclonal antibodies have gained tremendous importance in the treatment of a wide range of diseases over the last two decades (Kaplon and Reichert 2018)
Twenty-four hour post seeding, the baseline trans-endothelial electrical resistance (TEER) was measured and cells were incubated with the various antibodies (100 μM) in presence or absence of Charge patches affect tumor uptake and biodistribution To investigate the impact of charge patches on in vivo tumor uptake and distribution into selected tissues, we employed variants of an IgG1 antibody, which was derived from an anti-CD44 antibody and developed as a non-binding antibody, i.e., it had no detectable affinity to a specific target
The charge differences lead to differences in systemic clearance (clearance in hFcRn TG32 transgenic mice for antibody with negative charge patches (AbNeg), AbBal, and antibody with positive patches (AbPos): 4.0, 5.3, and 41 mL/day/kg)
Summary
Monoclonal antibodies have gained tremendous importance in the treatment of a wide range of diseases over the last two decades (Kaplon and Reichert 2018). The distinctive combination of high target binding affinity, exquisite specificity, and extraordinarily long plasma half-lives have been pivotal to their clinical success (Conner et al 2020). The exceptional plasma residence time is afforded by salvage mediated through the neonatal Fc. Arguably, it is the delivery to the target site, which restricts efficacy of antibody therapy in many cases. Improving uptake into solid tumors is an important challenge for current research (Tang and Cao 2021). The presence of cells exposed to insufficient amounts of antibody within a tumor under treatment restricts efficacy, but may foster the development of resistance against a targeted treatment (Thurber et al 2008).
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