Prostate-specific antigen (PSA) is widely used as a diagnostic marker for the detection of prostate cancer in men. We have generated stable hybridomas producing specific monoclonal antibodies (MAbs) of the IgG class against PSA from fusions of splenocytes from immunized mice with myeloma cells. The hybridomas were adapted into serum-free media and cultured in CELLine CL-1000 bioreactors to produce milligram quantities of MAbs. Cross-reactivity study demonstrated that all the MAbs reacted did not cross-react with several other types of tumor antigens. Two of the MAbs were successfully radiolabeled by the iodogen method. The (125)I-labeled MAbs demonstrated strong binding to PSA on the surface of the LNCaP cells (Kd of 1.16 x 10(-9) M and 1.4 x 10(-9) M). Thus the (125)I-labeled MAbs retained their immunoreactivity and possessed high affinity and is potentially useful for binding to tumor cells. In conclusion, the MAbs can be used to develop radioimmunodiagnostic, radioimaging, and immunohistochemistry techniques for the early detection and treatment of prostate cancer.
Early diagnosis of bone metastases is crucial to prevent skeletal-related events, and for that, the non-invasive techniques to diagnose bone metastases that make use of image-guided radiopharmaceuticals are being employed as an alternative to traditional biopsies. Hence, in the present work, we tested the efficacy of a gallium-68 (68Ga)-based compound as a radiopharmaceutical agent towards the bone imaging in positron emitting tomography (PET). For that, we prepared, thoroughly characterized, and radiolabeled [68Ga]Ga-NODAGA-pamidronic acid radiopharmaceutical, a 68Ga precursor for PET bone cancer imaging applications. The preparation of NODAGA-pamidronic acid was performed via the N-Hydroxysuccinimide (NHS) ester strategy and was characterized using liquid chromatography-mass spectrometry (LC-MS) and tandem mass spectrometry (MSn). The unreacted NODAGA chelator was separated using the ion-suppression reverse phase-high performance liquid chromatography (RP-HPLC) method, and the freeze-dried NODAGA-pamidronic acid was radiolabeled with 68Ga. The radiolabeling condition was found to be most optimum at a pH ranging from 4 to 4.5 and a temperature of above 60 °C. From previous work, we found that the pamidronic acid itself has a good bone binding affinity. Moreover, from the analysis of the results, the ionic structure of radiolabeled [68Ga]Ga-NODAGA-pamidronic acid has the ability to improve the blood clearance and may exert good renal excretion, enhance the bone-to-background ratio, and consequently the final image quality. This was reflected by both the in vitro bone binding assay and in vivo animal biodistribution presented in this research.