Production of 177Lu and formulation of Ethylene diamine tetramethylene phosphonate [EDTMP] kits as a bone-seeking radiopharmaceutical

Owing to its favourable decay characteristics 177Lu [T1/2= 6.71 d, Ebeta[max]= 497 keV] is an attractive radionuclide for various therapeutic applications. Ethylene diamine tatramethylene phosphonate [EDTMP] is one of the most widely used ligands which form stable complexes with various radionuclides and all the complexes. Enriched 176Lu2O3 was dissolved in 0.1 N HCl and evaporated several times and 176LuCl3 target was irradiated at 2.6x1013 n.Cm- 2.S-1 thermal neutron flux for 14 days.177LuCl3 was dissolved in 1N HCl. EDTMP was dissolved in double distilled water at pH=7.5-8.5 and freeze-dried kits was radiolabeled with 177LuCl3. Distribution studies were done in healthy mice. The yield of 177Lu was [220 TBq/g; 6000 Ci/g], the radionuclidic purity was 99%.The radiolabeling yield of EDTMP kits at 37°C after 30 min and 4 hours was 98 +/- 0.5% and after 72 hours was 90 +/- 2.1%, the in vitro stability in human serum at 37°C up to 72 hours post radiolabeling was 85 +/- 1.8%.The biodistribution studies of 177Lu-EDTMP and 177LuCl3 in normal mice showed skeleton uptake and low soft-tissue concentration. In this study, we produce 220 TBq/g [6000 Ci/g] of 177Lu by neutron activation of 176Lu in the Tehran Research Reactor. Our results showed 177Lu-EDTMP as a bone-seeking radiopharmaceutical. Due to its suitable nuclear characteristics 177Lu appears to be worthwhile for palliative therapy of bone metastasis

[Production and quality control of technetium-99m radiolabeled monoclonal antibody against colon cancer cells]

Binding a monoclonal antibody to tumor associated antigens is an effective method for cancer therapy because these agents can specifically target malignant cells. In fact, monoclonal antibodies are effective agents for diagnosis, grading and treatment of different kinds of cancers. In this research, a new monoclonal antibody against colon cancer cells was prepared and radiolabeling with technetium-99m evaluated. This research was done in three parts: preparation of hybridoma cell against colon cancer cell line [HT29], production of monoclonal antibody, determination of its characterizations and radiolabeling with technetium-99m. mAb-D2 is an IgG1 with affinity constant of 7.2x10[9] M[-1] which can recognize CEA in tumor cells. Radiolabeling showed that [99m]Tc-HYNIC-mAb-D2 complex is stable, immunoradioactive, and has a desirable biodistribution. In this study, we gained a new radiopharmaceutical that may be a good candidate for radioimmunoscintigraphy

Synthesis, development and preclinical comparison of two new peptide based freeze-dried kit formulation 99mTc-EDDA-Tricine-HYNIC-TOC and 99mTc-EDDA-Trinice-HYNIC-TATE for somatostatin receptor positive tumor scintigraphy

Somatostatin receptor [sstr] scintigraphy with [111In diethylenetriaminepentaacetic acid]-octreotide [[111In-DTPA]-OC] has became a routine diagnostic procedure in oncology. However, it suffers from some drawbacks concerning the limited availability, suboptimal imaging properties and elevated radiation burden of 111In. In this study synthesis, conjugation and preclinical evaluation of two new freeze-dried kit formulation based on somatostatin analogues, Tyr3-Octreotide [TOC] and Tyr3-octreotate [TATE], designed for the labeling with 99mTc are described. After cleavage from the resin and preparation of the cyclized peptides, these compounds were conjugated with 6-hydrazinopyridine-3-carboxylic acid [HYNIC] in solution. Radiolabeling of HYNIC peptide conjugates was performed at high specific activity using one-step kits formulation based on tricine and ethylenediamine-N,N? -diacetic acid [EDDA] as co-ligands. Both, 6-hydrazinopyridine-3-carboxylic acid0-Tyr3-Octreotide [HYNIC-TOC] and 6-hydrazinopyridine-3-carboxylic acid0-Tyr3-Octreotate [HYNIC-TATE], showed a specific and high rate of internalization after 4 h in AR4-2J rat pancreatic tumor cells, [11.2 +/- 0.8 and 18.1 +/- 1.2 respectively]. Biodistribution studies in AR4-2J tumor-bearing rats showed rapid clearance of both analogues from all sstr-negative tissues except the kidneys. The specific uptake in tumor and sstr-positive tissues especially pituitary, pancreas and adrenals were observed. After 4 h the adrenals to pancreas uptake ratio for HYNIC-TOC was higher than that of HYNIC-TATE. Although both compounds had high kidney and low liver excretion, for HYNIC-TATE, it was lower. The results suggest these two new peptide based freeze-dried kits might be of great promise for clinical application in imaging of somatostatin receptor-positive tumors

[Application of radioimmunoassay technique for determination of antigen concentration in different cells with a new monoclonal antibody]

Binding a monoclonal antibody to tumor associated antigens is an effective method for cancer therapy because these agents can specifically target malignant cells, in fact monoclonal antibodies are effective agents for diagnosis, grading and treatment of different kinds of cancers. In this research, a new monoclonal antibody against colon cancer cells was prepared and antigen concentration in different cells determined by a radioimmunoassay method using iodine [I-125] labeled protein G. 125I-labeled protein G percent binding to white blood cell, HT29, LS180 and MCF7 cell lines were 7.1%, 91.2%, 75.8% and 40.2%, respectively. Regarding importance of monoclonal antibody applications, it is necessary to find an efficient method for their evaluation in cancer therapy. In this method, a radioactive agent with no count restriction was used. Also by this method, amount of the antigen can be easily quantified

Preparation, formulation and quality control of one step Kit - 99mTc -EDDA/HyNic - Tyr - Octreotide as a peptide radiopharmaceutical for imaging somatostatin receptor positive tumors

The high expression of somatostatin receptors in many tumours, have made receptor scintigraphy with 111In-DTPA-Octreotide a widly used procedure in nuclear medicine. Despite its clinical success, some limitation and drawbacks of radiolabelling with 111In remain, especially those concerned with the cost, availability and physical decay properties of this radionuclide. 99mTc-EDDA/HYNIC-Tyr3-TOC was studied as a new agent with the potential to replace Octreoscan in somatostatin receptor scintigraphy. This hydrazinonicotinic acid derivatized somatostatin complex contains ethylenediamine N,N diacetic acid [EDDA] as a co-ligand resulting in a high in vitro and in vivo stability. High labeling yields [>90%] were achieved at high specific activities. Charactrization via HPLC, biodistribution and receptor binding of the resulting complex are described. The formulation developed enables rapid and simple labeling of 99mTc-EDDA/HYNIC-TOC in a manner suitable for clinical setting