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| 2. |
- Feridani, Amir, et al.
(författare)
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Combined flow cytometry and confocal laser scanning microscopy for evaluation of BR96 antibody cancer cell targeting and internalization.
- 2007
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Ingår i: Cytometry Part A. - : Wiley. - 1552-4930 .- 1552-4922. ; 71A:6, s. 361-370
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Tidskriftsartikel (refereegranskat)abstract
- Background: Monoclonal antibodies (mAb) are important tools in the management of tumor disease, and the discovery of antibodies with both specific cancer cell targeting and capacity to enter the cells by internalization are critical to improve the therapeutic efficacy. Method: Antibody cancer cell targeting and internalization properties of fluoroscein-conjugated mAb made against Lewis Y (BR96) were evaluated quantitatively and qualitatively by means of flow cytometry (FCM) and confocal laser scanning microscopy (CLSM), respectively, on cells from a rat tumor cell line (BN7005-H1D2). Results: The study demonstrated a specific binding of BR96 to LewisY (LeY) located in the cell membrane and as BR96/LeY immunocomplexes (BR96/LeY) internalized into the cytoplasm. BR96/LeY was internalized into about 15% of the cells, usually distributed throughout the cytoplasm, but also located close to the nuclei. Cytotoxic effects by BR96 were indicated, and CLSM visualized subpopulations containing cells with bound or internalized BR96/LeY that possessed morphologically pyknotic nuclei and disrupted DNA. Conclusion: The spatial-temporal pattern by BR96 cell targeting and internalization processes of BR96/LeY into the cancer cells expressing LeY was demonstrated by FCM and CLSM. Used together, the FCM and CLSM techniques provide a valuable tool for preclinical analyses of antibody targeting and their capacities as carriers of cytotoxic conjugates for the use in cancer therapy.
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| 3. |
- Garkavij, Michael, et al.
(författare)
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Enhanced radioimmunotargeting of 125I-labeled L6-biotin monoclonal antibody (MAb) by combining preload of cold L6 MAb and subsequent immunoadsorption in rats
- 1995
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Ingår i: Cancer Research. - 1538-7445. ; 55:23 Suppl, s. 5874-5880
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Tidskriftsartikel (refereegranskat)abstract
- The present study investigates whether tumor:normal tissue uptake ratios of radiolabeled monoclonal antibodies can be further improved by a combination of extracorporeal immunoadsorption (ECIA) and preload with unlabeled idiotypic monoclonal antibody. Athymic rats, heterotransplanted with human lung carcinoma under the kidney capsule (SR tumor) and i.m. (IM tumor), were divided into four study groups: controls, ECIA, preload, and combined preload+ECIA. The preload+ECIA procedure reduced the whole-body and plasma activity by 48 and 89%, respectively. After such combined procedure, the uptake of 125I-labeled L6-biotin in SR tumors was unchanged, while the uptake in normal tissues was considerably reduced. Tumor (T):bone marrow ratio was then increased by 17.5 times (after ECIA) and by 4.5 times (24 h after ECIA). Similar enhancements were achieved for T:liver and T:kidney ratios. For the IM tumors, the ratios were not as high as for SR tumors. The effects on T:normal ratios of preload+ECIA in combination were synergistic. The combined procedure resulted both in an increased uptake and prolonged persistence of 125I-labeled L6-biotin in the SR tumors and also in a reduction of corresponding uptake values in organs critical for radiation.
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| 4. |
- Garkavij, Martin, et al.
(författare)
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Extracorporeal whole-blood immunoadsorption enhances radioimmunotargeting of iodine-125-labeled BR96-biotin monoclonal antibody
- 1997
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Ingår i: Journal of Nuclear Medicine. - 0161-5505. ; 38:6, s. 895-901
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the efficacy of tumor radioimmunotargeting with 125I-labeled BR96-biotin monoclonal antibody using a new method, whole-blood immunoadsorption (WBIA), based on direct adsorption of unbound monoclonal antibody (MAb) from blood without preceding separation of plasma. METHODS: Highly tumor-reactive, internalizing, chimeric BR96 MAb of isotype IgG1 binds to a tumor-associated Lewis-type (Le(Y)) cell surface antigen. Forty-six Brown Norwegian male rats were inoculated intramuscularly and beneath the liver or kidney capsule with syngeneic rat colon carcinoma BN7005, expressing Lewis-type antigen, and investigated. The rats were injected intravenously with 3.5-4.5 MBq 125I-labeled BR96-biotin. Twenty of the rats underwent WBIA starting 5 or 12 hr after injection. About six blood volumes were passed through an avidin-gel adsorption column during 2 hr. RESULTS: By using WBIA, whole-body radioactivity was reduced by 50%, and plasma activity by 85%. Both directly after completion of WBIA and 33 hr later, the activity uptake in tumors manifested only a nonsignificant decrease as compared with corresponding controls (p > 0.05) and had approximately similar time-activity curves. Uptake ratios for tumor (T):bone marrow, T:liver, T:kidney and T:lung were enhanced 2.3- to 3.5-fold in all three tumor models, as compared with controls. The ratio of liver tumor to bone marrow was improved from 10:1 to 30:1. CONCLUSION: This new method of WBIA yields significantly improved radioimmunotargeting of highly tumor-reactive, internalizing MAb BR96.
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| 5. |
- Garkavij, Michael, et al.
(författare)
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Improving radioimmonotargeting of tumors. Variation in the amount of L6 MAb administered, combined with an immunoadsorption system (ECIA)
- 1993
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Ingår i: Acta Oncologica. - : Informa UK Limited. - 1651-226X .- 0284-186X. ; 32:7-8, s. 853-859
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Tidskriftsartikel (refereegranskat)abstract
- Extracorporeal immunoadsorption (ECIA) is a new method for the selective removal of circulating radiolabeled monoclonal antibodies (MAb) from plasma to increase the uptake in tumor versus normal tissues (T/N-ratio). To ascertain whether the amount of MAb affects T/N ratios immediately and 24 h after ECIA, we used a rat model with two tumor sites--one intramuscular (im) and one below the subrenal capsule (SR). Extracorporeal immunoadsorption was done with an avidin-agarose column after injection of 125I-labeled biotinylated L6 MAb. The animals received 10, 50 or 250 micrograms of L6 only (controls), or followed by ECIA. The efficacy of the procedure in removing plasma activity was 80-95%. For both tumor sites, the highest T/N-ratios were obtained with 10 micrograms L6. All T/N-ratios significantly improved for SR tumors by a factor ranging from 3.2 (lung) to 12.6 (bone marrow). The T/N-ratios were still elevated 24 h after ECIA. Injection of larger amounts of MAb, probably causing a higher degree of tumor saturation, will not necessarily improve the T/N ratio after ECIA.
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| 6. |
- Mårtensson, Linda, et al.
(författare)
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A nonsurgical technique for blood access in extracorporeal affinity adsorption of antibodies in rats.
- 2007
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Ingår i: Artificial Organs. - : Wiley. - 0160-564X .- 1525-1594. ; 31:4, s. 312-316
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Tidskriftsartikel (refereegranskat)abstract
- Monoclonal antibodies for targeting cytotoxic conjugates to tumor cells are currently being evaluated together with extracorporeal affinity adsorption. The aim of the adsorption was to reduce undesired side effects in normal organs and to increase the tumor-to-normal tissue ratios. This technique is also applicable to several other therapeutic areas such as immune-mediated disorders, that is, autoimmunity, allergy, and transplantation rejection. We describe an improved technique for extracorporeal affinity adsorption of radiolabeled biotinylated antibodies in rats. Blood access is established through the tail artery and tail vein, without surgical insertion of permanent catheters. This technique is simple, does not require surgery, and causes only minimal stress to the animals. In addition, experiments can be carried out on several animals simultaneously. This new technique is of considerable benefit for studying extracorporeal affinity adsorption in rats, as experiments can be carried out with negligible anatomical and physiological interventions, compared to previously used techniques.
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| 7. |
- Mårtensson, Linda, et al.
(författare)
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Determining maximal tolerable dose of the monoclonal antibody BR96 labeled with 90Y or 177Lu in rats: establishment of a syngeneic tumor model to evaluate means to improve radioimmunotherapy.
- 2005
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Ingår i: Clinical Cancer Research. - 1078-0432. ; 11:19 Pt 2, s. 7104-7108
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To evaluate therapeutic strategies, it is essential to use biological models reflecting important aspects of the clinical situation. The aim of the present study was to compare the maximal tolerable dose of the monoclonal antibody BR96 labeled with Y-90 or Lu-177 in immunocompetent rats. Maximal tolerable dose was defined as the highest activity that allows 100% of the animals to survive without clinical signs, such as infections, bleeding, or diarrhea, and with < 20% loss in body weight. Experimental Design: Increasing activity levels of BR96 labeled with Y-90 or Lu-177 were administered to groups of rats. Blood parameters, body weight, and general performance were monitored for 8 weeks. Results: Two days postinjection, all groups had decreased leukocyte counts down to 5% to 15% of initial values. Initiation of recovery (at 14-21 days) showed a dose-response relationship. All groups, except the group given the highest activity of Y-90 had complete resolution in their leukopenia. The decrease in platelets was delayed to days 7 to 14 postinjection with a dose dependent response regarding both severity of the nadir (10-40% of initial value) and the start of recovery. Animals in the groups given the highest activities of both Y-90 and Lu-177 exhibited skin infections on day 21. Conclusions: The results showed good reproducibility and dose-dependent toxicity for both radionuclides, indicating that the maximal tolerable dose for Lu-177 - BR96 (1,000 MBq/kg) is 1.7 times that for Y-90 - BR96 (600 MBq/kg) in rats. This model makes it feasible to evaluate strategies to escalate therapeutic doses to tumors without increasing normal tissue toxicity.
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| 8. |
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| 9. |
- Mårtensson, Linda, et al.
(författare)
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Reduced myelotoxicity with sustained tumor concentration of radioimmunoconjugates in rats after extracorporeal depletion.
- 2007
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Ingår i: Journal of Nuclear Medicine. - 0161-5505. ; 48:2, s. 269-276
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate the possibility of decreasing the myelotoxicity associated with radioimmunotherapy (RIT) by extracorporeal depletion of radioimmunoconjugates (RIC) from the circulation. The optimal combination of radionuclide and the time interval between injection of the RIC and the subsequent extracorporeal depletion procedure was assessed in immunocompetent rats, with respect to both myelotoxicity and tumor concentration of RIC. Methods: Rats were injected with (177)tumor Y-90-labeled antibody conjugate (mAb-DOTA-biotin) (mAb is monoclonal antibody; DOTA is 1,4,7,10-tetraazacyclododecane-N,N',N",N'''-tetraacetic acid) and subjected to removal of the conjugate from the circulation by extracorporeal affinity adsorption treatment (ECAT) 12, 24, or 48 h after injection. Myelotoxicity was assessed by analysis of blood parameters for 10 wk. The effect of ECAT on the tumor concentration of RIC was evaluated in parallel by scintillation camera imaging in rats injected with In-111-labeled RIC. Results: ECAT reduced the blood content of RIC by 95%. Thus, myelotoxicity was significantly milder in animals subjected to ECAT than that in controls. The timing of ECAT influenced the rate and level of bone marrow recovery, with an earlier recovery in animals subjected to ECAT early after injection. The toxicity-reducing effect of ECAT was more distinct in animals injected with Lu-177-labeled RIC than in animals injected with 90Y-labeled RIC. Scintillation camera imaging of tumors before and after ECAT revealed that subjecting animals to ECAT at 12 h after injection considerably reduced the total activity in tumors (34%), whereas the effect was lower at both 24 h (18%) and 48 h (18%) after injection. Conclusion: ECAT can efficiently reduce myelotoxicity associated with RIT, and the concentration of RIC in tumor can be sustained, provided ECAT is performed at an optimal time after antibody administration. The choice of radionuclide for RIT in combination with ECAT is important, as the physical half-life is crucial for the toxicity-reducing potential of ECAT at a specific time.
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