Fc-engineered monoclonal antibodies to reduce off-target liver uptake

BACKGROUND

Radiolabeled-antibodies usually display non-specific liver accumulation that may impair image analysis and antibody biodistribution. Here, we investigated whether Fc silencing influenced antibody biodistribution. We compared recombinant 89Zr-labeled antibodies (human IgG1 against different targets) with wild-type Fc and with mutated Fc (LALAPG triple mutation to prevent binding to Fc gamma receptors; FcγR). After antibody injection in mice harboring xenografts of different tumor cell lines or of immortalized human myoblasts, we analyzed antibody biodistribution by PET-CT and conventional biodistribution analysis.

RESULTS

Accumulation in liver was strongly reduced and tumor-specific targeting was increased for the antibodies with mutated Fc compared with wild-type Fc.

CONCLUSION

Antibodies with reduced binding to FcγR display lower liver accumulation and better tumor-to-liver ratios. These findings need to be taken into account to improve antibody-based theragnostic approaches.

Stratégies de ciblage spécifique de la tumeur fondées sur les caractéristiques des antigènes tumoraux et du microenvironnement tumoral

L’immunothérapie à base d’anticorps monoclonaux (AcM) connaît un plein essor en cancérologie. En 2020, plus de 40% des anticorps approuvés par la FDA (Food and Drug Administration) (34 sur 84 anticorps, selon The Antibody Society) ont une indication pour les thérapies anti-cancéreuses. Contrairement à la chimiothérapie standard, ils démontrent un bien meilleur profil de tolérance pour les patients. Malgré cela, des effets indésirables néfastes peuvent survenir en raison du ciblage de l’antigène qui est également exprimé au niveau des tissus sains. C’est pourquoi des stratégies émergentes visent à optimiser le format des anticorps et à tenir compte des particularités du microenvironnement tumoral pour conférer une action encore plus spécifique de l’anticorps au niveau tumoral.

Structured illumination fluorescence microscopy with distorted excitations using a filtered blind-SIM algorithm

Structured illumination microscopy (SIM) is a powerful technique for obtaining super-resolved fluorescence maps of samples, but it is very sensitive to aberrations or misalignments affecting the excitation patterns. Here, we present a reconstruction algorithm that is able to process SIM data even if the illuminations are strongly distorted. The approach is an extension of the recent blind-SIM technique, which reconstructs simultaneously the sample and the excitation patterns without a priori information on the latter. Our algorithm was checked on synthetic and experimental data using distorted and nondistorted illuminations. The reconstructions were similar to that obtained by up-to-date SIM methods when the illuminations were periodic and remained artifact-free when the illuminations were strongly distorted.

Integrated polarization rotator made of periodic asymmetric buried Ta2O5 / silica sol-gel waveguides

A ridge waveguide technology exhibiting high polarization dependency is developed for new efficient multi-section passive polarization rotator applications. In the presented configuration, the calculated mode coupling between the waveguide sections is very efficient and allows a polarization rotation with a high extinction ratio at lambda=1,55 mum. Experimental results show efficient polarization rotation with low cross-talk levels (-16dB) and no significant excess losses between sections. However, the overall transmission efficiency is limited by propagation losses and coupling losses to standard optical fibers.