Noninvasive ImmunoPET imaging of PD-L1 expression in non-small cell lung cancer and bladder cancer using [Zr]Zr-DFO-Durvalumab.

PURPOSE

ImmunoPET imaging of PD-L1 has emerged as a promising strategy for patient stratification and treatment response monitoring in immunotherapy. This study aimed to evaluate [Zr]Zr-DFO-Durvalumab in noninvasive imaging of PD-L1 expression in non-small cell lung cancer (NSCLC) and bladder cancer.

MATERIALS AND METHODS

Durvalumab was conjugated with -SCN-Bn-DFO and labeled with [Zr]Zr-oxalate, achieving high radiochemical purity (> 99 %) and stability. PD-L1 expression in human NSCLC (H1975, A549) and bladder cancer (HT1376, T24) cell lines was characterized via flow cytometry and immunofluorescence. binding and uptake studies were conducted to assess specificity. ImmunoPET imaging and biodistribution analyses were performed in mouse xenograft models. Additionally, fluorescence-guided imaging using IRDye 800CW-labeled Durvalumab was evaluated.

RESULTS

H1975 and HT1376 cells exhibited strong PD-L1 expression and high tracer uptake, while A549 and T24 cells were low in PD-L1 expression. PET imaging revealed significantly higher uptake in PD-L1-positive tumors. At 48 h p.i., the accumulation in H1975 tumor was 10.73 ± 1.89 %ID/g, compared to 4.47 ± 0.55 %ID/g in A549 tumor ( = 0.0219) and 4.60 ± 0.46 %ID/g in blocking control ( = 0.0228). HT1376 tumor reached 10.63 ± 1.35 %ID/g, significantly higher than T24 (4.10 ± 0.89 %ID/g, = 0.0037), blocking (4.10 ± 0.92 %ID/g, = 0.0036), and [Zr]Zr-DFO-IgG control (5.67 ± 0.90 %ID/g, = 0.0089). Tumor-to-muscle ratios at 48 h for H1975 and HT1376 tumors were 14.30 ± 2.02 and 15.00 ± 1.62, respectively, indicating excellent contrast. Fluorescence imaging with IRDye 800CW-Durvalumab further confirmed the uptake in PD-L1-specific tumors. No significant histological abnormalities were observed in major organs. The estimated human effective dose was 0.0522 mSv/MBq.

CONCLUSION

[Zr]Zr-DFO-Durvalumab enables specific, high-contrast ImmunoPET and fluorescence imaging of PD-L1-expressing NSCLC and bladder cancers. This dual-modality imaging platform holds potential for noninvasive assessment of PD-L1 status and personalized immunotherapy planning.