Radiosynthesis and evaluation of ytterbium-175 labeled bleomycin as therepeutic agent

Bleomycins are DNA-binding biomolecules, which can be used as targeted therapy carriers when labeled with particle-emitters such as Yb-175. In this work the development of Yb-175 bleomycin [[175]Yb-BLM] has been reported. Yb-175 chloride was obtained by thermal neutron irradiation [3 × 10[13] n.cm[-2].s[-1]] of natural Yb2O3 samples at various neutron fluxes and irradiation times. The radionuclide dissolved in acidic media [120mCi/mg] was used in the bleomycin [5 mg] labeling in buffer solution and warming at 60[degree sign]C for 48 h. Radiochemical purity was determined by ITLC as well as specific activity calculation followed by stability studies. Biodistribution studies of free Yb-175 and [175]Yb-BLM were performed in wild-type mice up to 8 days. At optimized conditions radiochemical purity of 97 +/- 0.88% and specific activity of 1360 MBq/mM was obtained. Biodistribution studies of free Yb-175 demonstrated liver and bone uptake while in case of [175]Yb-BLM the target tissues were lung, liver and spleen.[175]Yb-BLM complex was prepared at the optimized conditions and suitable characteristics. The accumulation of the radiolabeled compound in lungs, liver and spleen demonstrates a similar pattern to the other radiolabeled bleomycins. Further studies are to be performed for application of this labeled compound in tumor-bearing models

Production and quality control of [67Ga]-DOTA-trastuzumab for radioimmunoscintigraphy

Breast cancer radioimmunoscintigraphy targeting HER2/neu expression is a growing field of work in nuclear medicine research. In this study, trastuzumab was successively labeled with [[67]Ga] GaCl3 after conjugation with DOTA-NHS-ester. The conjugates were purified by molecular filtration, the average number of DOTA conjugated per mAb was calculated and total concentration was determined by spectrophotometric method. DOTA-Trastuzumab was labeled with [67]Ga. Radiochemical purity, integrity of protein after radiolabeling and stability of [67]Ga-DOTA-Trastuzumab were determined followed by biodistribution studies in wild-type rats [30 +/- 5.5 micro Ci, 2, 4 and 24 h p.i.]. The radioimmunoconjugate was prepared with a radiochemical purity of higher than 95% [RTLC]. The average chelate to antibody ratio [c/a] for the conjugate used in this study was 5.8:1. The final compound was stable in presence of PBS at 37[degree sign]C and room temperature. The sample was showed to have similar patterns of migration in the gel electrophoresis similar to the native protein. The accumulation of the radiolabeled antibody in liver, spleen, kidney, heart and other tissues demonstrates. [67]Ga-DOTA-Trastuzumab was prepared as a surrogate for important clinically applicable radionuclides used in SPECT and PET including In-111 and Cu-64 as a model of radiolabeling. It is also a potential compound for molecular imaging of SPECT for diagnosis and treatment studies and follow-up of HER2 expression in oncology

Production, quality control and imaging of [64]Cu-ATSM in healthy rabbits for clinical applications

[[64]Cu]diacetyl-bis[N[4]-methylthiosemicarbazone] [[[64]Cu]ATSM] is a well-established hypoxia imaging tracer with reproducible production and significant specifity. In this work the high yield production and quality control as well as imaging studies in healthy rabbits is reported. Copper-64 produced via the [68]Zn[p, alpha n] [64]Cu nuclear reaction [30 MeV protons at 180 micro A] was used for the preparation of [[64]Cu]diacetyl-bis[N4-methylthiosemicarbazone][[ [64]Cu]ATSM]. Followed by quality control and administration to healthy rats as well as healthy rabbits for biodistribution and imaging studies respectively. [64]Cu[2+] [500 mCi, separation yield> 95%, radionuclide purity>96%] was used for [[64]Cu]ATSM production [radiochemical purity>99%, specific activity of 300 Ci/mmol] followed by administration to healthy rabbits and coincidence imaging demonstrating uptake in liver, kidney and bowel as shown by other reports in various rodents and human. [[64]Cu]ATSM radiopharmaceutical is produced and now available in large quantities for research and/or clinical trials in the country

Preliminary imaging studies of [[61]Cu] diacetyl-bis [N[4]-methylthiosemi-carbazone] in normal and hypoxic tumor models

[[61]Cu] diacetyl-bis [N[4] -methylthiosemicarbazone] [[[61]Cu] ATSM] is a well-established hypoxia imaging tracer with simple production and significant specifity. In this work the accumulation of the tracer is studied in wild-type, necrotic and hypoxic fibrosarcoma tumors. [[61] Cu] ATSM was prepared using ATSM ligand and [[61]Cu] CuOAc followed by i.v. administration and imaging studies in wid-type rats and hypoxic fibrosarcoma-bearing mic.e [[61] Cu] ATSM with high radiochemical purity [>99%, HPLC, RTLC] was injected to wild-type rats as well as hypoxic and necrotic fibrosarcoma-bearing mice followed by imaging up to 3 hours. [[61] Cu] ATSM was mainly accumulated in liver, as well as kidney and bladder and less but still significant in brain of wild-type rats. A significant and hypoxia-specific tumor/non tumor ratio in hypoxic models was observed by co-incidence imaging 2h post inection, while in necrotic and 12-week tumor-induced mice very slight tumor uptakes were detected. [[61]Cu] ATSM is a positron emission tomography [PET] radiotracer for selective tumor hypoxia imaging from necrotic and proliferative tumors

Production, quality control and biological evaluation of [153]Sm-EDTMP in wild-type rodents

Nowadays various bone pain palliative therapeutic agents have been developed for bone metastases. Among those, [153]Sm-ethylenediamine tetramethylene phosphonic acid [[153]Sm-EDTMP] is the major therapeutic agent which is widely used in the world. In this study, production, quality control and biodistribution studies of this therapeutic radiopharmaceutical have been presented and followed by imaging studies in a wild-type rabbit for the first time in order to make preparations for this agent to be officially approved in the country. [153]Sm-EDTMP was produced using [153]Sm-SmCl[3], prepared by neutron activation of an enriched [152]Sm sample [purity >98%], and in-house synthesized EDTMP in 4h at 100°C. The analytical data for the structure determination and purity of the ligand was obtained and shown to be identical to an authentic sample from a European vendor. The Radiochemical purity of [153]Sm-EDTMP was checked by RTLC and ITLC. The biodistribution of [153]Sm-EDTMP in wild-type rodents was checked and SPECT imaging as well as following sacrificing the animal. The radiolabeled Sm complex was prepared in high radiochemical purity [>99%, RTLC] followed by initial biodistribution data with the significant bone accumulation [>70%] of the tracer in 48h which is comparable with the reported methods. The produced [153]Sm-EDTMP properties suggest good potential for efficient use of this radiopharmaceutical for bone pain palliation and as substitute for other agents, such as [89]SrCl[2] and [32]P, currently used in the country

Evaluation of [[67]Ga] citrate in the detection of various microorganism infections in animal models

Gallium-67 citrate has been known as a good infection agent in nuclear medicine for decades. In this work the value of [67]Ga-citrate has been investigated in infected animal models using SPECT imaging at optimized/standardized conditions. The bacterial [Staphylococcus aureus; S.a. and Escherichia coli; E.c.] and fungal [Candidae albicans; C.a.] species from standard sources were cultured according to the standard procedures and wild-type NMRI rats were inoculated by the injection of 5x10[7] microorganisms [MO] into their thighs and animals incubated for infection site formation for 2 and 3 days followed by iv injection of freshly prepared [67]Ga-citrate [45-50 micro Ci] and SPECT imaging performed at 2, 4 and 24 hours post injection in parallel with control groups. In S.a.-infected rats [67]Ga-citrate demonstrated hot spot foci at all time intervals esp. 24h post injections in contrast with normal animal scans. In case of C.a., the infected animals also demonstrated significant accumulation foci being most significant after 24h. In E.c.-infected animals however weak positive scans were obtained even after 24 hours. Our animal models developed for the evaluation of new infection-targeting agents were successfully positive using [67]Ga scan. These models can also be used in the evaluation of newly developed antibiotics in animal models for in vivo studies. The efficacy of [67]Ga-scan in our microorganism infection models can be summarized as S.A.>C.a.>E.c.

Preparation, biodistribution and stability of [65 ZN] bleomycincomplex

Bleomycin [BLM] has been labeled with various radioisotopes and widely used in therapy and diagnosis. In this study BLM was labeled with [65Zn] zinc chloride and its distribution and stability in normal and tumor bearing mice was determined. The complex was obtained at the pH=2 in normal saline at 90 °C in 60 minutes. Radio-TLC showed an overall radiochemical yield of 95-97% [radiochemical purity >97%].The in vitro stability of the complex was determined in mice and human plasma. Preliminary studies were performed to determine distribution of [65Zn]BLM in normal and tumor bearing mice on the basis of these results. [65Zn]BLM may be used in therapeutic studies due to its suitable physico-chemical properties