Abstract LB491: PET imaging and response to amivantamab treatment of non-small cell lung cancer xenografts

Abstract Introduction: Amivantamab (AMI) a bispecific antibody, targets both epidermal growth factor receptor (EGFR) and mesenchymal-epithelial transition factor (c-MET) among other Fc mediated effector functions. AMI is approved as a monotherapy and in combination regimens for the treatment of locally advanced or metastatic NSCLC with activating EGFR mutations. However, there are currently no effective methods to project response to AMI treatment. Given its ability to noninvasively quantify antibody biodistribution and target engagement in tumors, PET imaging provides a powerful strategy to assess AMI response. We aim to determine in pre-clinical studies whether tumor uptake of [89Zr]Zr-DFO-AMI associates with response to AMI by quantifying the relationship between pretreatment tracer uptake and tumor growth inhibition. Methods: AMI was conjugated to p-SCN-Bn-deferoxamine (DFO) and radiolabeled with Zirconium-89 to generate [89Zr]Zr-DFO-AMI. Binding to EGFR and c-MET biotin-antigens was evaluated using a radioligand binding assay with a 5000-fold molar excess of unlabeled AMI for blocking the antigens. For in vivo studies, male and female xenografts were established using HCC827 (EGFR-mutant, high EGFR/cMET expression; n=16), H2170 (EGFR wild-type, moderate EGFR/cMET expression; n=20), and H520 (EGFR-null, no EGFR/cMET expression; n=10) NSCLC cell lines in athymic nude mice. Xenografts were injected with 1.85 MBq of [89Zr]Zr-DFO-AMI and imaged by PET at 4 days post-injection. Following imaging, mice were treated with AMI or isotype control (10 mg/kg) twice weekly for 30 days. Tumor volumes were monitored, and percent tumor growth inhibition (%TGI) was calculated and correlated with PET-derived standardized uptake values (SUVs). Results: [89Zr]Zr-DFO-AMI was synthesized with a specific activity of 0.148 MBq/µg and a radiochemical yield of 100%, as confirmed by radio-thin layer chromatography. Radioligand binding showed ∼4-fold higher EGFR binding and ∼7-fold higher c-MET binding in non-blocked vs. blocked conditions, confirming specificity. Pre-treatment PET imaging with [89Zr]Zr-DFO-AMI showed the highest uptake in HCC827 tumors (SUV = 4.84), followed by H2170 (SUV = 3.13) and H520 (SUV = 1.46). Treatment with AMI resulted in a 79% tumor growth inhibition in HCC827 xenografts, while minimal inhibition was observed in H2170 (%TGI = 20%) and H520 (%TGI = 4-14%) models. SUV in tumor strongly correlated with %TGI (r = 0.9446, Pearson). Conclusion: [89Zr]Zr-DFO-AMI specifically binds EGFR and c-MET. PET imaging with [89Zr]Zr-DFO-AMI is associated with response in the tested pre-clinical models.Acknowledgements: We thank Janssen for providing Amivantamab. We also acknowledge the UAB Small Animal Imaging Facility (P30CA013148) and the UAB Cyclotron Facility for Zirconium-89 production. This work was supported by NCI/NIH under Award Number 5R01CA255226. Citation Format: Mann Dangarwala, Aldred Mendez, Bernadette Marquez-Nostra. PET imaging and response to amivantamab treatment of non-small cell lung cancer xenografts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(8_Suppl):Abstract nr LB491.