Durvalumab (anti-PD-L1) is a selective, high affinity human IgG1 mAb that blocks programmed cell death ligand-1 (PD-L1) binding to PD-1 (IC50=0.1 nM) and CD80 (IC50=0.04 nM). MW=146.3 kDa.
The labeled radioligand shows good affinity to high PD-L1 expression cells and could be blocked with excess unlabeled intact durvalumab.[1]
The peak tumor uptake of 124I-Durva-F(ab’)2 was close to 124I-Durva, but much earlier (5.29±0.42% ID/g for 124I-Durva-F(ab’)2 at 12 h vs 5.18±0.73% ID/g for 124I-Durva at 48 h). Compared with 124I-Durva, an accelerated blood clearance was observed for 124I-Durva-F(ab’)2, allowing for a higher tumor-to-background ratio.[1]
[1] Cheng Y, et al. Mol Pharm. 2022 Mar 4.