Immuno-PET imaging of CD30-positive lymphoma using ⁸⁹Zr-desferrioxamine-labeled CD30-specific ac-10 antibody

The CD30-specific antibody-drug conjugate, brentuximab vedotin, is approved for the treatment of relapsed, refractory Hodgkin lymphomas and systemic anaplastic large T-cell lymphomas. Multiple ongoing clinical trials are investigating brentuximab vedotin efficacy in other CD30-positive hematologic malignancies. Because CD30 expression varies among different types of lymphoma and can also change during the course of treatment, companion diagnostic imaging of CD30 could be a valuable tool in optimizing patient-specific brentuximab vedotin treatment regimens. Methods: The mouse antihuman CD30 antibody AC-10 was radiolabeled with the positron-emitting radionuclide ⁸⁹Zr. The stability and specificity of ⁸⁹Zr-desferrioxamine (DFO)-labeled CD30-specific AC-10 antibody (⁸⁹Zr-DFO-AC-10) was evaluated in vitro. The pharmacokinetics of ⁸⁹Zr-DFO-AC-10 was studied in BALB/c nude mice bearing subcutaneous human Karpas 299 tumors (CD30-positive model) or A-431 tumors (CD30-negative model) using PET/CT imaging, biodistribution studies, and autoradiography. Results: AC-10 was conjugated with a DFO B chelator and radiolabeled with ⁸⁹Zr to give formulated ⁸⁹Zr-DFO-AC-10 with a radiochemical yield of 80%, radiochemical purity greater than 99%, and specific activity of 111-148 MBq/mg. ⁸⁹Zr-DFOAC-10 was stable in mouse and human sera and preserved the immunoreactivity toward CD30. Biodistribution data showed the highest tissue accumulation of ⁸⁹Zr-DFO-AC-10 in CD30-positive tumors, with 37.9% ± 8.2% injected activity per gram of tissue at 72 h after injection, whereas uptake in CD30-negative tumors was 11.0% ± 0.4%. The specificity of ⁸⁹Zr-DFO-AC-10 binding to CD30 in vivo was confirmed by blocking studies. Time-activity curves showed that between 24 and 144 h after injection, tumor-to-muscle ratios increased from 18.9 to 51.8 in the CD30-positive model and from 4.8 to 8.7 in the CD30-negative model. Tumor-to-blood ratios also increased, from 3.2 to 13.6 and from 1 to 2 in the CD30-positive and-negative models, respectively. Conclusion: Our results demonstrate that for measuring CD30 expression, ⁸⁹Zr-DFO-AC-10 is a sensitive PET agent with high tumor-to-normal-tissue contrast. ⁸⁹Zr-DFO-AC-10 is a promising CD30-imaging radiotracer for clinical translation in patients with various lymphomas and other diseases.