Junfeng Yu

90Y-oxine-ethiodol, a potential radiopharmaceutical for the treatment of liver cancer

Ethiodol (or lipiodol) is selectively retained in hepatocellular carcinoma and is used as a vehicle to deliver radioactive agents following intraarterial hepatic infusion. We prepared the lipophilic complex 90Y-oxine with a radiolabeling efficiency of 97.6+/-1.1%. After extraction into ethiodol, a stability test in serum at 37 degrees C showed that 87.8% of the 90Y remained ethiodol-bound for 7 days. Bremsstrahlung imaging of a rabbit for 48 h confirmed that the homogeneous mixture of radiolabeled 90Y-oxine and ethiodol stayed in the targeted liver lobe. This radiopharmaceutical is thus a potential candidate for the treatment of non-resectable liver cancer.

Radiolabeling of magnetic targeted carriers (MTC) with indium-111

Magnetic targeted carriers (MTC) are magnetically susceptible microparticles that can be physically targeted to a specific site. MTC were radiolabeled with (111)In using three different methods. Reaction parameters were investigated in order to optimize the final properties of the labeled MTC. The reaction parameters studied were chelation agent, chelation time, temperature, radiolabeling time, solvent, and molar ratios. A 97.7 +/- 0.9% binding efficiency and plasma stability of 92.6 +/- 0.1% over 7 days were achieved when 2-p-aminobenzyl-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetra-acetic acid (ABz-DOTA) was used as the chelating agent. A preliminary animal biodistribution study confirmed the binding stability. The labeling of the MTC with the diagnostic isotope (111)In was undertaken to allow for quantitative imaging and dosimetry prior to therapy with (90)Y radiolabeled MTC.

Radiolabelling of poly(histidine) derivatized biodegradable microspheres with the 188Re tricarbonyl complex [188Re(CO)3(H2O)3]+

ObjectivesMany radiopharmaceuticals have been studied as radiation synovectomy agents. In this study, we developed a new potential agent for radiation synovectomy: poly(lactic acid)–histidine (PLA–his) microspheres radiolabelled with [188Re(CO)3(H2O)3]+. MethodsThe reaction conditions for the chelation of [188Re(CO)3(H2O)3]+ and the radiolabelling of PLA microspheres were optimized and the stabilities for both steps tested in vitro. ResultsThe chelation efficiency of [188Re(CO)3(H2O)3]+ reached 93.12±1.82% with >95% radiochemical purity once the colloidal and free 188Re were removed by a small Sep-Pak column (Plus QMA). More than 90% of radioactivity stayed in the [188Re(CO)3(H2O)3]+ form over 5 h. The radiolabelling efficiency of PLA–his microspheres with [188Re(CO)3(H2O)3]+ was above 92%. After 3 days incubation at 37°C in calf serum, more than 80% of the radioactivity was still bound to the microspheres. ConclusionSuch microspheres are potentially useful as a radiation synovectomy agent for the treatment of chronically inflamed arthritic joints. Furthermore, they might be valuable in cancer brachytherapy.

Applied radioactivity in radiation synovectomy with [188Re]rhenium sulfide suspension.

BackgroundEarly experience demonstrated absorbed dose in radiation synovectomy is about 100 Gy. For reaching this dose, the applied radioactivity should be calculated. MethodTwenty-nine synovitic models of rabbit were treated by intra-articular injection of [188Re]rhenium sulfide and histological changes of synovium and cartilage were examined. The applied radioactivity was calculated by method of absorbed dose factor. In clinical, eleven haemophilic patients with haemarthrosis were performed radiation synovectomy with treated [188Re]rhenium sulfide. The synovial thickness was evaluated by MR and its value was used to calculate the applied radioactivity. After radiation synovectomy, all patients were followed up by synovial thickness, regional inflammation, and clinical course including bleeding frequency. ResultsIn rabbit models, the synovitic membrane can be eliminated by calculated radioactivity as planed without damaging the joint cartilage. In patients study, all patients exhibited significant reductions in synovial thickness and inflammation after radiation synovectomy with the planed radioactivities of [188Re]rhenium sulfide. Post-procedure bleeding frequency reduction in excellent and good reached to 63.6% by 18 months. In the cases of joint bleeding, the need for antihaemophilic factor treatment decreased immensely. Most of the recurrent episodes of bleeding were mild, subsiding with local means. ConclusionThe applied radioactivity in radiation synovectomy could be calculated according to thickness of inflamed synovium. Further study including comparison therapeutic results from calculated individual activities with results from fixed activities and long-term follow-up is warranted.