[<sup>64</sup>Cu]Cu-NOTA-Ivonescimab: a novel PET tracer for imaging VEGF expression in colorectal carcinoma

Colorectal cancer (CRC) has high rates of recurrence and metastasis, underscoring the need for improved diagnostic imaging methods to support accurate disease monitoring and inform treatment decisions. In this study, we present ⁶⁴CuCu-NOTA-Ivonescimab, a novel ImmunoPET tracer that specifically targets vascular endothelial growth factor-A (VEGF-A), which is upregulated in CRC. Ivonescimab was conjugated to a NOTA chelator and radiolabeled with copper-64, achieving over 99% radiochemical purity and demonstrating robust in vitro stability. <i>In vivo</i> PET imaging of HCT-116 CRC xenograft models showed specific, time-dependent tumor uptake of ⁶⁴CuCu-NOTA-Ivonescimab, peaking at 13.73 ± 0.95 %ID/g at 48 h post-injection. This was significantly higher than in the blocking group (5.20 ± 0.10 %ID/g, <i>P</i> = 0.00011). Furthermore, Ivonescimab conjugated with the near-infrared dye IRDye 800CW allowed complementary optical imaging, displaying significantly higher fluorescence intensity in tumors (25.49 ± 8.69 × 10⁸ p/s/cm²/sr) compared to blocking controls (4.66 ± 0.95 × 10⁸ p/s/cm²/sr, <i>P</i> = 0.0145) at 48 hours post-injection. Together, these findings establish ⁶⁴CuCu-NOTA-Ivonescimab as a promising imaging agent that offers precise, noninvasive quantification of VEGF expression, with potential to enhance diagnostic accuracy and guide therapy in CRC.