Work

Light-enhanced cytotoxicity and intracellular trafficking of the PD-L1-targeting photoimmunoconjugate EITC-atezolizumab

Year: 2025

Type: article

Abstract: BACKGROUND: Photodynamic therapy (PDT) uses light to generate reactive oxygen species (ROS) that initiate cytotoxic responses in cancer cells. Photoimmunotherapy (PIT) improves PDT specificity by linking photosensitizers (PS) to monoclonal antibodies. A promising monoclonal antibody (mAb) for immunoconjugates is atezolizumab (Tecentriq), an EMA/FDA-approved PD-L1 immune checkpoint inhibitor for treating non-small cell lung cancer (NSCLC). OBJECTIVE: Our goal was to: Optimize the cytotoxic efficacy of a photoimmunoconjugate of eosin-5-isothiocyanate and atezolizumab (EITC-atezolizumab) in NSCLC cells; Study the uptake and intracellular transport of atezolizumab; Evaluate EITC-atezolizumab as a candidate for photochemical internalization (PCI) of the ribosome-inactivating protein gelonin. METHODS: Cytotoxic efficacy of EITC-atezolizumab was evaluated in NSCLC cell lines H1975 (PD-L1-high) and A549 (PD-L1-low) using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. Confocal microscopy was employed to observe the uptake and intracellular localization of AlexaFluor647-atezolizumab and its colocalization with either LysoTracker™Blue or an anti-CD63 antibody labelled with Alexa488. RESULTS: organelles peaking at 6 h. In A549 cells, AlexaFluor647-atezolizumab showed sustained accumulation in LysoTracker™ Blue+ vesicles for up to 24 h. CONCLUSION: NSCLCs.

Source: Biomedicine & Pharmacotherapy

DOI: 10.1016/j.biopha.2025.118550