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Oslo, Norway

Heyerdahl H.,University of Oslo | Abbas N.,University of Oslo | Brevik E.M.,Algeta ASA | Mollatt C.,University of Oslo | And 2 more authors.
PLoS ONE | Year: 2012

Background: The aim of this study was to investigate therapeutic efficacy and normal tissue toxicity of single dosage and fractionated targeted alpha therapy (TAT) in mice with HER2-expressing breast and ovarian cancer xenografts using the low dose rate radioimmunoconjugate 227Th-DOTA-p-benzyl-trastuzumab. Methodology/Principal Findings: Nude mice carrying HER2-overexpressing subcutaneous SKOV-3 or SKBR-3 xenografts were treated with 1000 kBq/kg 227Th-trastuzumab as single injection or four injections of 250 kBq/kg with intervals of 4-5 days, 2 weeks, or 4 weeks. Control animals were treated with normal saline or unlabeled trastuzumab. In SKOV-3 xenografts tumor growth to 10-fold size was delayed (p<0.01) and survival with tumor diameter less than 16 mm was prolonged (p<0.05) in all TAT groups compared to the control groups. No statistically significant differences were seen among the treated groups. In SKBR-3 xenografts tumor growth to 10-fold size was delayed in the single injection and 4-5 days interval groups (p<0.001) and all except the 4 weeks interval TAT group showed improved survival to the control groups (p<0.05). Toxicity was assessed by blood cell counts, clinical chemistry measurements and body weight. Transient reduction in white blood cells was seen for the single injection and 4-5 days interval groups (p<0.05). No significant changes were seen in red blood cells, platelets or clinical chemistry parameters. Survival without life threatening loss of body weight was significantly prolonged in 4 weeks interval group compared to single injection group (p<0.05) for SKOV-3 animals and in 2 weeks interval group compared with the 4-5 days interval groups (p<0.05) for SKBR-3 animals. Conclusions/Significance: The same concentration of radioactivity split into several fractions may improve toxicity of 227Th-radioimmunotherapy while the therapeutic effect is maintained. Thus, it might be possible to increase the cumulative absorbed radiation dose to tumor with acceptable toxicity by fractionation of the dosage. © 2012 Heyerdahl et al. Source

Heyerdahl H.,University of Oslo | Roe K.,Akershus University Hospital | Brevik E.M.,Algeta ASA | Dahle J.,Nordic Nanovector AS
International Journal of Radiation Oncology Biology Physics | Year: 2013

Purpose: The purpose of this study was to investigate the effect of α-particle-emitting 227Th-trastuzumab radioimmunotherapy on tumor vasculature to increase the knowledge about the mechanisms of action of 227Th-trastuzumab. Methods and Materials: Human HER2-expressing SKOV-3 ovarian cancer xenografts were grown bilaterally in athymic nude mice. Mice with tumor volumes 253 ± 36 mm3 (mean ± SEM) were treated with a single injection of either 227Th-trastuzumab at a dose of 1000 kBq/kg body weight (treated group, n=14 tumors) or 0.9% NaCl (control group, n=10 tumors). Dynamic T1-weighted contrast-enhanced magnetic resonance imaging (DCEMRI) was used to study the effect of 227Th-trastuzumab on tumor vasculature. DCEMRI was performed before treatment and 1, 2, and 3 weeks after therapy. Tumor contrast-enhancement curves were extracted voxel by voxel and fitted to the Brix pharmacokinetic model. Pharmacokinetic parameters for the tumors that underwent radioimmunotherapy were compared with the corresponding parameters of control tumors. Results: Significant increases of kep, the rate constant of diffusion from the extravascular extracellular space to the plasma (P<.05), and kel, the rate of clearance of contrast agent from the plasma (P<.01), were seen in the radioimmunotherapy group 2 and 3 weeks after injection, compared with the control group. The product of k ep and the amplitude parameter A, associated with increased vessel permeability and perfusion, was also significantly increased in the radioimmunotherapy group 2 and 3 weeks after injection (P<.01). Conclusions: Pharmacokinetic modeling of MRI contrast-enhancement curves evidenced significant alterations in parameters associated with increased tumor vessel permeability and tumor perfusion after 227Th-trastuzumab treatment of HER2-expressing ovarian cancer xenografts.© 2013 Elsevier Inc. Source

Nordic Nanovector AS | Date: 2012-12-12

The present invention relates to chimieric or humanized antibodies derived from the mouse monoclonal antibody HH1. The applications of the present invention include therapeutic applications in which pharmaceutical compositions comprising the antibodies of the present invention or radioimmunoconjugates hereof are used for treating B-cell malignancies.

Nordic Nanovector As | Date: 2014-06-06

The present invention relates to radioimmunoconjugates that are capable of upregulating expression of one or more antigens. The upregulated antigens can be the antigens that are targeted by the radioimmunoconjugates or different antigens expressed on the same cells. The present invention also relates to methods of treating cancer and diseases and disorders of the immune system by utilizing this enhanced expression of antigens.

Repetto-Llamazares A.H.V.,Nordic Nanovector AS | Repetto-Llamazares A.H.V.,University of Oslo | Larsen R.H.,Sciencons Ltd. | Mollatt C.,University of Oslo | And 2 more authors.
Current Radiopharmaceuticals | Year: 2013

The biodistribution of the anti-CD37 radioimmunoconjugate 177Lu-tetraxetan-tetulomab (177Lu-DOTA-HH1) was evaluated. Biodistribution of 177Lu-tetraxetan-tetulomab was compared with 177Lu-tetraxetan-rituximab and free 177Lu in nude mice implanted with Daudi lymphoma xenografts. The data showed that 177Lu-tetulomab had a relevant stability and tumor targeting properties in the human lymphoma model. The half-life of 177Lu allowed significant tumor to normal tissue ratios to be obtained indicating that 177Lu-tetraxetan-tetulomab could be suitable for clinical testing. The biological and effective half-life in blood was higher for 177Lu-tetraxetan-tetulomab than for 177Lu-tetraxetan-rituximab. The biodis-tribution of 177Lu-tetraxetan-tetulomab did not change significantly when the protein dose was varied from 0.01 to 1 mg/kg. Dosimetry calculations showed that the absorbed radiation doses to normal tissues and tumor in mice were not significantly different for 177Lu-tetraxetan-tetuloma b and 177Lu-tetraxetan-rituximab. The absorbed radiation doses were extrapolated to human absorbed radiation doses. These extrapolated absorbed radiation doses to normal tissues for 177Lu-tetraxetan-tetulomab at an injection of 40 MBq/kg were significantly lower than the absorbed radiation doses for 15 MBq/kg Zevalin, suggesting that higher tumor radiation dose can be reached with 177Lu-tetraxetan-tetulomab in the clinic. © 2013 Bentham Science Publishers. Source

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