Usefulness of PET-guided surgery with 64Cu-labeled cetuximab for resection of intrapancreatic residual tumors in a xenograft mouse model of resectable pancreatic cancer

Preclinical Safety Evaluation of Intraperitoneally Administered Cu-Conjugated Anti-EGFR Antibody NCAB001 for the Early Diagnosis of Pancreatic Cancer Using PET

Detecting tumor lesions <1 cm in size using current imaging methods remains a clinical challenge, especially in pancreatic cancer. Previously, we developed a method to identify pancreatic tumor lesions ≥3 mm using positron emission tomography (PET) with an intraperitoneally administered 64Cu-labeled anti-epidermal growth factor receptor (EGFR) antibody (64Cu-NCAB001 ipPET). Here, we conducted an extended single-dose toxicity study of 64Cu-NCAB001 ipPET in mice based on approach 1 of the current ICH M3 [R2] guideline, as our new drug formulation contains 45 μg of the antibody. We used NCAB001 labeled with stable copper isotope instead of 64Cu. The total content of size variants was approximately 6.0% throughout the study. The relative binding potency of Cu-NCAB001 to recombinant human EGFR was comparable to that of cetuximab. The general and neurological toxicities of Cu-NCAB001 ipPET at 62.5 or 625 μg/kg were assessed in mice. The no-observed-adverse-effect level of Cu-NCAB001 was 625 μg/kg, a dose approximately 1000-fold higher at the μg/kg level than the dose of 64Cu-NCAB001 in our formulation (45 µg). The size variants did not affect the safety of the formulation. Therefore, clinical studies on the efficacy of 64Cu-NCAB001 ipPET for early detection of pancreatic cancer using PET imaging can be safely conducted.

Characterization and Stabilization of a New 64Cu-Labeled Anti-EGFR Antibody NCAB001 for the Early Detection of Pancreatic Cancer with Positron Emission Tomography

Early diagnosis of pancreatic cancer using current imaging modalities remains challenging. We have developed a new approach to identify tumor lesions ≥ 3 mm in the pancreas by positron emission tomography (PET) with a new intraperitoneally administered ⁶⁴Cu-labeled anti-epidermal growth factor receptor (EGFR) antibody (encoded as NCAB001), called ⁶⁴Cu-NCAB001 ipPET. Generally, in clinical research, a radiometal-antibody complex must be prepared immediately before use at the imaging site. To make ⁶⁴Cu-NCAB001 ipPET available to daily clinical practices in a sustainable way, the NCAB001-chelator conjugate and ⁶⁴Cu-NCAB001 must be characterized and stabilized. NCAB001 was manufactured under cGMP conditions. NCAB001 was conjugated with a bifunctional chelator (p-SCN-Bn-PCTA), and the antibody-chelator conjugate (PCTA-NCAB001) was characterized by LC/MS and ELISA. Thereafter, to effectively manufacture ⁶⁴Cu-NCAB001, we developed a new formulation to stabilize PCTA-NCAB001 and ⁶⁴Cu-NCAB001. An average of three PCTA chelators were conjugated per molecule of NCAB001. The relative binding potency of PCTA-NCAB001 was comparable to cetuximab. The formulation consisting of acetate buffer, glycine, and polysorbate-80 stabilized PCTA-NCAB001 for a year-long storage. Additionally, this formulation enabled the stabilization of ⁶⁴Cu-NCAB001 for up to 24 h after radiolabeling with a sufficient radioactivity concentration for clinical use. These results may accelerate the future use of ⁶⁴Cu-NCAB001 ipPET in clinical settings for the early diagnosis and treatment of pancreatic cancer.