title: Preparation and radiolabeling of a lyophilized (kit) formulation of DOTA-rituximab with ⁹⁰Y and ¹¹¹In for domestic radioimmunotherapy and radioscintigraphy of non-Hodgkin's lymphoma.
abstract: BACKGROUND
  On the basis of results of our previous investigations on 90Y-DTPA-rituximab and in order to fulfil national demands to radioimmunoconjugates for radioscintigraphy and radioimmunotherapy of Non-Hodgkin's Lymphoma (NHL), preparation and radiolabeling of a lyophilized formulation (kit) of DOTA-rituximab with 111In and 90Y was investigated.
  
  
  METHODS
  111In and 90Y with high radiochemical and radionuclide purity were prepared by 112Cd (p,2n)111In nuclear reaction and a locally developed 90Sr/90Y generator, respectively. DOTA-rituximab immunoconjugates were prepared by the reaction of solutions of p-SCN-Bz-DOTA and rituximab in carbonate buffer (pH = 9.5) and the number of DOTA per molecule of conjugates were determined by transchelation reaction between DOTA and arsenaso yttrium(III) complex. DOTA-rituximab immunoconjugates were labeled with 111In and 90Y and radioimmunoconjugates were checked for radiochemical purity by chromatography methods and for immunoreactivity by cell-binding assay using Raji cell line. The stability of radiolabeled conjugate with the approximate number of 7 DOTA molecules per one rituximab molecule which was prepared in moderate yield and showed moderate immunoreactivity, compared to two other prepared radioimmunoconjugates, was determined at different time intervals and against EDTA and human serum by chromatography methods and reducing SDS-polyacrylamide gel electrophoresis, respectively. The biodistribution of the selected radioimmunoconjugate in rats was determined by measurement of the radioactivity of different organs after sacrificing the animals by ether asphyxiation.
  
  
  RESULTS
  The radioimmunoconjugate with approximate DOTA/rituximab molar ratio of 7 showed stability after 24 h at room temperature, after 96 h at 4°C, as the lyophilized formulation after six months storage and against EDTA and human serum. This radioimmunoconjugate had a biodistribution profile similar to that of 90Y-ibritumomab, which is approved by FDA for radioimmunotherapy of NHL, and showed low brain and lung uptakes and low yttrium deposition into bone.
  
  
  CONCLUSIONS
  Findings of this study suggest that further investigations may result in a lyophilized (kit) formulation of DOTA-rituximab which could be easily radiolabeled with 90Y and 111In in order to be used for radioimmunotherapy and radioscintigraphy of B-cell lymphoma in Iran.
authors: Department of Radiopharmacy, Faculty of Pharmacy, Tehran University of Medical Sciences, P,O, Box: 14155-6451, Tehran, Iran. gholipour@razi.tums.ac.ir.
authors: Nazila
authors: N
authors: Gholipour
authors: Amir Reza
authors: AR
authors: Jalilian
authors: Ali
authors: A
authors: Khalaj
authors: Fariba
authors: F
authors: Johari-Daha
authors: Kamal
authors: K
authors: Yavari
authors: Omid
authors: O
authors: Sabzevari
authors: Ali Reza
authors: AR
authors: Khanchi
authors: Mehdi
authors: M
authors: Akhlaghi
mesh_terms: D000818:Animals; D058846:Antibodies, Monoclonal, Murine-Derived / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D045744:Cell Line, Tumor; D004339:Drug Compounding; D005612:Freeze Drying; D006573:Heterocyclic Compounds, 1-Ring / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D006801:Humans; D018796:Immunoconjugates / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D007205:Indium Radioisotopes; D007553:Isotope Labeling; D008228:Lymphoma, Non-Hodgkin / Q000532:radiotherapy; D008297:Male; D016499:Radioimmunotherapy; D011877:Radionuclide Imaging; D051381:Rats; D000069283:Rituximab; D012709:Serum Albumin / Q000737:chemistry; D014018:Tissue Distribution; D015021:Yttrium Radioisotopes
chemical_list: D058846:Antibodies, Monoclonal, Murine-Derived; D006573:Heterocyclic Compounds, 1-Ring; D018796:Immunoconjugates; D007205:Indium Radioisotopes; D012709:Serum Albumin; D015021:Yttrium Radioisotopes; C071349:1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid; D000069283:Rituximab