In vitro and in vivo study on the treatment of non-small cell lung cancer with radionuclide labeled PD-L1 nanobody

Abstract

Purpose: Nanobodies have become promising carriers due to excellent in vivo properties. Radiopharmaceutical therapy targeting programmed cell death ligand 1 (PD-L1) is an effective therapeutic strategy. Our study aimed to explore therapeutic efficacy of ¹³¹I labeled PD-L1 nanobody (Nb109) in non-small cell lung cancers (NSCLCs) in vitro and in vivo.

Methods: ¹³¹I-Nb109 was synthesized by chloramine-T method. We implemented stability analysis, SDS-PAGE and lipid-water partition coefficient test to assess its quality. Cell uptake assay and SPECT/CT scan were applied to evaluate its ability to target NSCLCs (H460 and A549). CCK8 assay and in vivo efficacy assay were conducted to estimate its therapeutic effect in H460 tumors. Damage-associated molecular patterns (DAMPs) release in H460 cells incubated with ¹³¹I-Nb109 was investigated by western blot and ATP test kit.

Results: ¹³¹I-Nb109 was hydrophilic with high labeling rate (69.51-98.06%), radiochemical purity (99.17% ± 0.76%) and stability. Cell uptake experiments showed that H460 cells (PD-L1 positive) compared with A549 cells (PD-L1 negative) had higher ¹³¹I-Nb109 uptake. SPECT/CT imaging revealed the accumulation of ¹³¹I-Nb109 in H460 tumor within 48 h. ¹³¹I-Nb109 inhibited H460 tumor growth without toxic side effects in contrast with control group. It also induced H460 cells to release DAMPs (adenosine triphosphate, high mobility group box 1, and heat shock protein 70).

Conclusion: ¹³¹I-Nb109 had high stability, excellent ability to target and treatment PD-L1 positive tumors, and can improve tumor immunogenicity. The results of our study were expected to inspire the development of more novel radiopharmaceuticals to treat NSCLCs.

Keywords: Nanobody; Non-small cell lung cancers; Programmed cell death ligand 1; Radiopharmaceutical.