RESUMEN
Positron emission tomography (PET) with 89Zr-labeled monoclonal antibodies (mAbs) or other targeted vehicles (e.g., peptides, nanoparticles and cells), collectively called "89Zr-immuno-PET", can be used for better understanding of disease targets and the in vivo behavior of targeted drugs. This will become increasingly important in the development of next generation mAbs, which are characterized by high potency and/or multiple binding domains. This review provides practical information for researchers who want to implement 89Zr-immuno-PET for answering their own biological and pathological questions or for steering their own drug development program. An overview is given of the reagents, labeling protocols, quality tests and critical steps to come to high quality 89Zr-conjugates, while possibilities for further improvement are discussed. Since PET has the advantage of allowing quantitative imaging, information is provided about standardization of 89Zr quantification. Issues are summarized for consideration when starting preclinical or clinical 89Zr-immuno-PET studies, to enable at the end unequivocal interpretation of results. Finally, many appealing examples are provided of what can be learned from 89Zr-immuno-PET studies, while future directions are outlined. Most of the current examples are still on the characterization of mAbs in oncology, but the review will show that 89Zr-immuno-PET harbors potential for many kinds of targeted drugs and diseases, as well as for elucidating biological processes.
Asunto(s)
Neoplasias/diagnóstico por imagen , Radioisótopos/inmunología , Circonio/inmunología , Anticuerpos Monoclonales/inmunología , Sistemas de Liberación de Medicamentos/métodos , Humanos , Marcaje Isotópico/métodos , Neoplasias/inmunología , Tomografía de Emisión de Positrones/métodos , Radiofármacos/inmunologíaRESUMEN
Photodynamic therapy (PDT) is a promising approach for the treatment of superficially localized tumors. A limitation, however, is the lack of selectivity of the photosensitizers, which can result in severe toxicity. In this overview, the possibilities for using monoclonal antibodies (MAbs) for selective delivery of photosensitizers to tumors, are discussed. This approach is called photoimmunotherapy (PIT). For PIT to be successful, sufficient amounts of sensitizer should be coupled to the MAb without altering its biological properties. A challenging aspect herein is the hydrophobicity of therapeutic photosensitizers. Options for direct and indirect coupling of photosensitizers to MAbs are evaluated, while pros and cons are indicated. Special attention is paid to the quality testing of photoimmunoconjugates, as this information is important for further optimization of PIT. Results obtained thus far with PIT in in vitro and in vivo model systems are discussed. Despite the encouraging progress made, showing the high selectivity of photoimmunoconjugates, PIT still awaits initial clinical evaluation.
Asunto(s)
Anticuerpos Monoclonales , Sistemas de Liberación de Medicamentos/métodos , Inmunoconjugados , Neoplasias , Fármacos Fotosensibilizantes , Animales , Anticuerpos Monoclonales/administración & dosificación , Anticuerpos Monoclonales/inmunología , Anticuerpos Monoclonales/uso terapéutico , Humanos , Inmunoconjugados/farmacocinética , Inmunoconjugados/uso terapéutico , Inmunoterapia/métodos , Neoplasias/diagnóstico , Neoplasias/inmunología , Neoplasias/terapia , Fármacos Fotosensibilizantes/administración & dosificación , Fármacos Fotosensibilizantes/efectos adversos , Fármacos Fotosensibilizantes/inmunologíaRESUMEN
UNLABELLED: A novel, facile procedure for efficient coupling of high doses of (131)I to monoclonal antibodies (MAbs) was developed with minimal chemical and radiation damage. METHODS: To diminish the radiation and chemical burden during labeling, iodination was performed in a large reaction volume and by temporarily coating the MAb with a minimal amount of IODO-GEN. The MAb was coated by injection of IODO-GEN (dissolved in acetonitrile [MeCN]) into the aqueous MAb solution, and the coating was subsequently removed by addition of ascorbic acid. For chemoprotection before, during, and after PD-10 purification of the (131)I-MAbs, ascorbic acid and human serum albumin were used. The effects of autoradiolysis in the starting (131)I solution were countered by treatment with NaOH and ascorbic acid. For this so-called IODO-GEN-coated MAb method, the sensitive chimeric MAb MOv18 (c-MOv18) and the more robust murine MAbs K928 and E48 were used. The high-dose (131)I-labeled MAbs were characterized for radiochemical purity and MAb integrity by thin-layer chromatography, high-performance liquid chromatography, and sodium dodecyl sulfate polyacrylamide gel electrophoresis followed by phosphor imager quantification. The high-dose (131)I-labeled MAbs were also characterized for immunoreactivity. The radiopharmacokinetics and biodistribution of (131)I-c-MOv18 were analyzed in human tumor-bearing nude mice. For comparison, (131)I-c-MOv18 batches were made using the conventional chloramine-T or IODO-GEN-coated vial method. RESULTS: Conventional high-dose labeling of 5 mg c-MOv18 with 4.4 GBq (131)I resulted in a labeling yield of 60%, a radiochemical purity of 90%, an immunoreactive fraction of 25% (72% being the maximum in the assay used), and the presence of aggregation and degradation products. Using similar amounts of (131)I and MAb in the IODO-GEN-coated MAb method, 85%-89% overall radiochemical yield, at least 99.7% radiochemical purity, and full preservation of MAb integrity and immunoreactivity were achieved. For this labeling, 5 mg MAb were coated with 35 microg IODO-GEN during 3 min in a reaction volume of 6 mL. Also, biodistribution was optimal, and tumor accumulation was superior to that of coinjected (125)I-c-MOv18 labeled according to the conventional IODO-GEN-coated vial method. CONCLUSION: A new, facile, high-dose (131)I-labeling method was developed for production of (131)I-labeled MAbs with optimal quality for use in clinical radioimmunotherapy.
Asunto(s)
Anticuerpos Monoclonales/uso terapéutico , Indicadores y Reactivos , Radioisótopos de Yodo/uso terapéutico , Radioinmunoterapia , Receptores de Superficie Celular , Urea , Animales , Anticuerpos Monoclonales/inmunología , Anticuerpos Monoclonales/farmacocinética , Proteínas Portadoras/inmunología , Femenino , Receptores de Folato Anclados a GPI , Radioisótopos de Yodo/farmacocinética , Ratones , Ratones Desnudos , Proteínas de Neoplasias/inmunología , Neoplasias Ováricas/inmunología , Neoplasias Ováricas/radioterapia , Distribución Tisular , Urea/análogos & derivadosRESUMEN
The use of monoclonal antibodies (MAbs) directed against tumor-associated antigens for targeting of photosensitizers is an interesting option to improve the selectivity of photodynamic therapy (PDT). Hydrophilic photosensitizers are most suitable for conjugation to MAbs because of their water solubility. The photosensitizer aluminum (III) phthalocyanine tetrasulfonate [AlPc(SO3H)4] has many ideal photochemical properties; however, because of its hydrophilicity, the free form of this sensitizer does not readily reach the critical intracellular target and, therefore, is ineffective in PDT. On the basis of our previous studies, we hypothesized that AlPc(SO3H)4 might be suitable for PDT when coupled to internalizing tumor-selective MAbs. In this study, a reproducible procedure is presented for coupling of AlPc(SO3H)4 to MAbs via the tetra-glycine derivative AlPc(SO2Ngly)4. Conjugation was performed to chimeric MAb (cMAb) U36 and murine MAbs (mMAb) E48 and 425 using a labile ester. Conjugates showed preservation of integrity and immunoreactivity and full stability in serum in vitro. At molar ratios >4, the solubility of the conjugates decreased. Data on the in vitro efficacy of PDT showed that in the chosen experimental setup the internalizing AlPc(SO2Ngly)4-mMAb 425 conjugate was about 7500 times more toxic to A431 cells than the free sensitizer (IC50s, 0.12 nM versus 900 nM). The AlPc(SO2Ngly)4-mMAb 425 conjugate was also more toxic than meta-tetrahydroxyphenylchlorin-mMAb 425 conjugates and free meta-tetrahydroxyphenylchlorin that had been tested previously (M. B. Vrouenraets et al., Cancer Res., 59: 1505-1513, 1999) in the same system (IC50s, 7.3 nm and 2.0 nM, respectively). Biodistribution analysis of AlPc(SO2Ngly)4-125I-labeled cMAb U36 conjugates with different sensitizer:MAb ratios in squamous cell carcinoma-bearing nude mice revealed selective accumulation in the tumor, although to a lesser extent than for the unconjugated 125I-labeled cMAb U36, whereas tumor:blood ratios were similar. These findings indicate that AlPc(SO3H)4 has high potential for use in PDT when coupled to internalizing tumor-selective MAbs.
Asunto(s)
Anticuerpos Monoclonales/química , Inmunoconjugados/química , Indoles/química , Compuestos Organometálicos/química , Fotoquimioterapia/métodos , Fármacos Sensibilizantes a Radiaciones/química , Animales , Anticuerpos Monoclonales/farmacocinética , Carcinoma de Células Escamosas/tratamiento farmacológico , Carcinoma de Células Escamosas/inmunología , Carcinoma de Células Escamosas/metabolismo , Neoplasias de Cabeza y Cuello/tratamiento farmacológico , Neoplasias de Cabeza y Cuello/inmunología , Neoplasias de Cabeza y Cuello/metabolismo , Humanos , Inmunoconjugados/farmacocinética , Inmunoterapia/métodos , Indoles/administración & dosificación , Indoles/farmacocinética , Ratones , Ratones Desnudos , Compuestos Organometálicos/administración & dosificación , Compuestos Organometálicos/farmacocinética , Control de Calidad , Fármacos Sensibilizantes a Radiaciones/farmacocinética , Reproducibilidad de los Resultados , Distribución Tisular , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Coupling of photosensitizers to tumor-selective monoclonal antibodies (MAbs) is an attractive option for improving the selectivity of photodynamic therapy (PDT). For this purpose, hydrophilic sensitizers would be most suitable because of their solubility in water. However, such sensitizers are known to be ineffective in PDT, probably because they cannot readily pass the cell membrane and reach the critical intracellular target. We used the model compound TrisMPyP-PhiCO(2)H, a hydrophilic porphyrin derivative, to test the hypothesis that hydrophilic photosensitizers might become of therapeutic value when directed into the tumor cell by use of internalizing MAbs. TrisMPyP-PhiCO(2)H was conjugated using a labile ester. Conjugates showed no impairment of integrity on SDS-PAGE, full stability in serum in vitro, and optimal immunoreactivity when the sensitizer:MAb ratio was
Asunto(s)
Anticuerpos Monoclonales/farmacología , Inmunoconjugados/farmacología , Fotoquimioterapia/métodos , Fármacos Fotosensibilizantes/farmacología , Porfirinas/farmacología , Animales , Anticuerpos Monoclonales/química , Anticuerpos Monoclonales/farmacocinética , Carcinoma de Células Escamosas/tratamiento farmacológico , Carcinoma de Células Escamosas/inmunología , Carcinoma de Células Escamosas/metabolismo , Cromatografía Líquida de Alta Presión , Electroforesis en Gel de Poliacrilamida , Neoplasias de Cabeza y Cuello/tratamiento farmacológico , Neoplasias de Cabeza y Cuello/inmunología , Neoplasias de Cabeza y Cuello/metabolismo , Humanos , Inmunoconjugados/química , Inmunoconjugados/farmacocinética , Radioisótopos de Yodo , Marcaje Isotópico/métodos , Ratones , Ratones Desnudos , Trasplante de Neoplasias , Fármacos Fotosensibilizantes/química , Fármacos Fotosensibilizantes/farmacocinética , Porfirinas/química , Porfirinas/farmacocinética , Distribución Tisular , Células Tumorales CultivadasRESUMEN
UNLABELLED: We investigated the safety and pharmacokinetics of (131)I-labeled chimeric monoclonal antibody MOv18 ((131)I-c-MOv18 IgG) in patients with ovarian cancer and the estimated radiation dose to cancer-free organs and tumor. METHODS: Three patients were injected intravenously with 3 GBq (131)I-c-MOv18. Toxicity was evaluated according to the World Health Organization toxicity scales. Blood sampling was performed for 12 wk after injection. Whole-body and SPECT imaging was performed frequently. Dose rates were obtained with a portable dose-rate measure. Quantitative activity analysis of several organs was performed with the region-of-interest technique. Absorbed doses were calculated using MIRDOSE3. RESULTS: Transient changes in hematologic profiles were seen in 2 patients. Pancytopenia developed in 1 patient; on analysis, she entered the study probably with exhausted bone marrow reserves. Nonhematologic toxicity was mild. No human antichimeric antibody responses were observed. Mean isolation time was 12 d. The plasma elimination half-life increased almost 3-fold compared with that after tracer doses of c-MOv18. Dosimetry showed mean absorbed doses of 163, 380, 276, 338, 781, and 216 cGy, for whole-body, liver, kidney, spleen, lung, and red marrow, respectively. Tumor-absorbed doses ranged from 600 to 3800 cGy. All patients achieved a stable disease state, as confirmed by CT and carcinoma-associated antigen CA 125, lasting from 2 to >6 mo. CONCLUSION: (131)I-labeled c-MOv18 can safely be given to patients with noncompromised bone marrow reserves and may have therapeutic potential particularly in patients with minimal residual disease.
Asunto(s)
Anticuerpos Monoclonales/administración & dosificación , Radioisótopos de Yodo/administración & dosificación , Neoplasias Ováricas/radioterapia , Radioinmunoterapia , Anticuerpos Monoclonales/farmacocinética , Femenino , Humanos , Inmunoglobulina G , Inyecciones Intravenosas , Radioisótopos de Yodo/farmacocinética , Radioisótopos de Yodo/uso terapéutico , Persona de Mediana Edad , Neoplasias Ováricas/diagnóstico por imagen , Radioinmunoterapia/efectos adversos , Cintigrafía , Dosificación RadioterapéuticaRESUMEN
A limitation of photodynamic therapy is the lack of tumor selectivity of the photosensitizer. To overcome this problem, a protocol was developed for coupling of meta-tetrahydroxyphenylchlorin (mTHPC), one of the most promising photosensitizers, to tumor-selective monoclonal antibodies (MAbs). mTHPC was radiolabeled with 131I to facilitate the assessment of the in vitro and in vivo behavior. After the modification to 131I-mTHPC-(CH2COOH)4, thus increasing the water solubility and creating a functional moiety suitable for coupling, conjugation was performed using a labile ester. Insoluble aggregates were not formed when mTHPC-MAb conjugates with a molar ratio of up to 4 were prepared. These conjugates showed a minimal impairment of the integrity on SDS-PAGE, full stability in serum in vitro, and an optimal immunoreactivity. To test the in vivo behavior of the mTHPC-MAb conjugates, the head and neck squamous cell carcinoma-selective chimeric MAb U36 was used in head and neck squamous cell carcinoma-bearing nude mice. Biodistribution data showed that the tumor selectivity of cMAb U36-conjugated mTHPC was increased in comparison with free mTHPC, despite the fact that conjugates with a higher mTHPC:MAb ratio were more rapidly cleared from the blood. Preliminary results on the in vitro efficacy of photodynamic therapy with MAb-conjugated mTHPC showed that mTHPC coupled to the internalizing murine MAb 425 exhibited more phototoxicity than when coupled to the noninternalizing chimeric MAb U36.
Asunto(s)
Anticuerpos Monoclonales/uso terapéutico , Inmunoconjugados/uso terapéutico , Mesoporfirinas/uso terapéutico , Fotoquimioterapia , Fármacos Fotosensibilizantes/uso terapéutico , Animales , Anticuerpos Monoclonales/farmacocinética , Humanos , Radioisótopos de Yodo , Mesoporfirinas/farmacocinética , Ratones , Distribución Tisular , Células Tumorales CultivadasRESUMEN
Four 99mTc-MAG3-biotin conjugates were synthesized to determine their potential use in antibody pretargeting strategies for radioimmunoscintigraphy (RIS). To use these 99mTc-MAG3-biotin conjugates as model compounds for 186Re-MAG3-biotin conjugates for radioimmunotherapy (RIT), nanomolar amounts of 99Tc were added as carrier to 99mTc. The biotin derivatives used for the preparation of the conjugates-biocytin, biotin hydrazide, biotinyl-piperazine, and biotinyl-diaminosuccinic acid-differed at the site that is regarded to be susceptible to hydrolysis by biotinidase present in human plasma. All four conjugates were produced with high radiochemical purity, were stable in PBS, and demonstrated full binding capacity to streptavidin. The 99mTc/99Tc-MAG3-labeled biotinyl-piperazine and biotinyl-diaminosuccinic acid conjugates were stable in mouse as well as human plasma, whereas the corresponding biocytin and biotin hydrazide conjugates were rapidly degraded. The biodistribution in nude mice at 30 min after injection was similar for all conjugates, and a rapid blood clearance and high intestinal excretion were both observed. It is concluded that the metabolic routing of a conjugate containing biotin and MAG3 is dominated by these two moieties. For this reason, MAG3-biotin conjugates do not seem suited for pretargeted RIT, for which quantitative and fast renal excretion is a prerequisite to minimize radiation toxicity. However, in a pretargeted RIS approach the 99mTc-MAG3-biotin conjugates might have potential.
Asunto(s)
Biotina/química , Tecnecio Tc 99m Mertiatida/análogos & derivados , Tecnecio Tc 99m Mertiatida/química , Animales , Biotina/análogos & derivados , Estabilidad de Medicamentos , Femenino , Ratones , Ratones Desnudos , Trazadores Radiactivos , Radioinmunodetección/métodos , Tecnecio Tc 99m Mertiatida/farmacocinética , Distribución TisularRESUMEN
BACKGROUND: Rhenium-186 (186Re) has ideal properties for adjuvant radioimmunotherapy (RIT). However, the lack of suitable methods for high dose 186Re labeling of monoclonal antibodies (MAbs) has hampered the use of 186Re in clinical RIT. After development of a chemically identical multistep procedure for the production of 186Re-MAG3-MAb and 99mTc/99Tc-MAG3-MAb conjugates for use as a matched pair, the authors now report on further progress to make this labeling method broadly applicable for high dose 186Re labeling. METHODS: The number of metal-MAG3 groups that can be coupled to a MAb without alteration of the biodistribution was investigated by radioimmunoscintigraphy (RIS) in patients with head and neck squamous cell carcinoma (HNSCC). For labeling with 500 mCi [186Re]ReO4-, an efficient chemoprotection was introduced to suppress the damaging effects of radiation during conjugation and conjugate purification. Furthermore, the authors developed strategies that make the procedure easy and safe to perform at any medical center. RESULTS: MAbs showed a minor variation in biodistribution in HNSCC patients when the number of metal-chelate groups per MAb varied between < 1 and 4.3. High dose 186Re-MAb conjugates (150-250 mCi) with a Re-MAG3:MAb ratio of 3.4 were obtained with a radiochemical purity of > 95% and minimal aggregate formation (< or = 6%). Furthermore, a semiautomated labeling device and a convenient 100 mCi labeling kit in the form of a dried 186Re-MAG3-TFP ester were developed. RIT studies in HNSCC-bearing nude mice showed that high dose 186Re-labeled MAb U36 is more effective than iodine-131-labeled MAb U36. CONCLUSIONS: High dose 186Re-MAb conjugates were prepared that exhibit an optimal stability, immunoreactivity, and pharmacokinetic behavior. The availability of a kit procedure for coupling 186Re to MAbs might open the possibility of a broad application of 186Re in RIT.
Asunto(s)
Anticuerpos Monoclonales/uso terapéutico , Carcinoma de Células Escamosas/radioterapia , Neoplasias de Cabeza y Cuello/radioterapia , Marcaje Isotópico/métodos , Radioinmunoterapia , Renio/uso terapéutico , Animales , Anticuerpos Monoclonales/farmacocinética , Humanos , Radioisótopos de Yodo , Ratones , Ratones Desnudos , Distribución TisularRESUMEN
The tissue distribution and biodynamics of 18F-labelled 5-fluorouracil (FU) are described and studied for correlation with its in vivo antitumor activity. The in vivo model consisted of Balb/c mice bearing a FU sensitive (Colon 26-10 carcinoma) tumor in the left and a less responsive (Colon 26 carcinoma) tumor in the right abdominal side of the animal. Distribution and efflux of 18F-label from tumor, blood, and other tissues were determined by obduction at 0.5, 1, 2, 4, and 6 h postintravenous injection. For a comparison, the 18F-labeled 5-fluoro-6-hydroxy and cis-5-fluoro-6-ethoxy uracil adducts were studied in the same in vivo model. For 18F-FU it was found that the 18F-label tumor kinetics rapidly fell into a biphasic mode: a relatively short 18F beta phase (18F t1/2 beta 21 +/- 3 min), linked with the total body metabolic capacity and clearance of the animal, and a longer 18F gamma phase, linked with the intrinsic intratumoral FU metabolism (Colon 26-10: 18F t1/2 gamma 10.3 h; Colon 26: 18F t1/2 gamma 5.6 h). It is proposed that the observed faster 18F efflux of the less responsive Colon 26 corresponds to an enhanced breakdown of 5-fluoronucleotides to 5-fluoronucleosides and subsequent elimination from the tumor cells. It is concluded that on PET scanning, measurement of the dynamic 18F t1/2 gamma and 18F t1/2 beta parameter is of prime importance for an insight in the in vivo tumor biology of a patient.
Asunto(s)
Neoplasias del Colon/metabolismo , Radioisótopos de Flúor/farmacocinética , Fluorouracilo/farmacocinética , Animales , Línea Celular , Neoplasias del Colon/tratamiento farmacológico , Femenino , Fluorodesoxiuridilato/metabolismo , Fluorouracilo/sangre , Fluorouracilo/uso terapéutico , Marcaje Isotópico/métodos , Cinética , Ratones , Ratones Endogámicos BALB C , Timidilato Sintasa/metabolismo , Distribución TisularRESUMEN
UNLABELLED: Our previous studies on the preparation of 186Re-MAb conjugates for clinical radioimmunotherapy (RIT) were extended with the aim to derive conjugates which have a high Re:MAb molar ratio, are stable in vitro and in vivo, have favorable biodistribution characteristics and can be used together with 99mTc-MAb conjugates as a matched pair in combined radioimmunoscintigraphy/RIT studies. METHODS: Rhenium and 99mTc-conjugates of intact MAb E48 were prepared according to our previously described multistep procedure using the MAG3 chelate and analyzed by protein mass spectrometry for the number of chelate molecules coupled to the MAb. For biodistribution analysis, tumor-free nude mice were simultaneously injected with 186Re-, 99mTc/99Tc- and/or 125I-labeled E48 IgG and dissected 1-48 hr postinjection. RESULTS: Rhenium-186-MAb conjugates with up to 20 Re-MAG3 groups per MAb molecule were prepared with an overall radiochemical yield of 40%-60%. The conjugates did not contain empty MAG3 groups and no aggregates were formed. Only conjugates with a 186Re-MAG3:MAb molar ratio higher than 12 demonstrated slightly impaired immunoreactivity to a maximum of 15% decrease at the 20:1 molar ratio. Biodistribution experiments revealed that a proportion of the conjugate became rapidly eliminated from the blood for conjugates with a Re-MAG3:MAb molar ratio higher than 8. In this case, an increased uptake of activity was observed in the liver and intestines. The 99mTc/99Tc-MAb conjugates showed a similar enhanced blood clearance when containing more than eight Tc-MAG3 groups, while dual labeling of MAbs revealed that the in vivo stability of the conjugated Re-MAG3 complex itself does not differ from the corresponding Tc-MAG3 complex. CONCLUSION: With the method described in this study, it is possible to prepare 186Re-MAG3-MAb conjugates that fulfil all the aforementioned criteria for use in clinical RIT. Coupling of too many metal-MAG3 groups to MAbs results in rapid blood clearance. At the same metal-MAG3:MAb molar ratio, 99mTc/99Tc-MAb conjugates show a similar pharmacokinetic behavior as 186Re-MAb conjugates and can thus be used to predict the localization of 186Re-labeled MAbs and make dosimetric predictions in individual patients.
Asunto(s)
Radioinmunodetección , Radioinmunoterapia , Radioisótopos , Renio , Tecnecio Tc 99m Mertiatida , Animales , Carcinoma de Células Escamosas/radioterapia , Neoplasias de Cabeza y Cuello/radioterapia , Ratones , Ratones Desnudos , Radioisótopos/farmacocinética , Radioisótopos/uso terapéutico , Renio/farmacocinética , Renio/uso terapéutico , Tecnecio Tc 99m Mertiatida/farmacocinética , Tecnecio Tc 99m Mertiatida/uso terapéutico , Distribución TisularRESUMEN
In previous studies we have shown that in mice bearing head and neck squamous cell carcinoma (HNSCC) xenografts, radioimmunotherapy (RIT) with 186Re-labeled MAb E48 resulted in complete regressions in one-third of the tumors (followup > 150 d). MAb E48 was labeled with 186Re following a novel labeling procedure developed at our institute. The injected dose was 600 microCi, which was the maximum tolerated dose (MTD; < 15% wt loss) in these studies. The mean size of the tumors was 140 +/- 60 mm3. To investigate whether the therapeutic efficacy of RIT in our xenograft model would be improved when treating smaller xenografts, mice bearing 2 HNSCC xenografts with a vol of 75 +/- 17 mm3 (number of mice, n = 6; number of tumors, t = 12) were treated with 600 microCi of 186Re-labeled MAb E48 IgG. All tumors completely regressed and did not regrow during followup (> 150 d). In all mice, weight loss did not exceed 10%. To obtain biodistribution data, mice bearing two xenografts with a vol of 58 +/- 31 mm3 were injected with 100 microCi of 186Re-labeled MAb E48 IgG. The maximum uptake in blood was 26.4% injected dose/g (%ID.g-1) at 2 h pi and was 53.1%ID.g-1 in the tumor at d 7 pi. In normal tissues, no nonspecific accumulation was observed. Based on these biodistribution data, the absorbed cumulative radiation dose was calculated. The accumulated dose in blood and tumor was 2004 cGy and 8580 cGy, respectively. In other tissues, the dose was less than 8.1% of the dose delivered to tumor.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Carcinoma de Células Escamosas/radioterapia , Radioinmunoterapia/métodos , Radioisótopos/uso terapéutico , Renio/uso terapéutico , Animales , Anticuerpos Monoclonales , Relación Dosis-Respuesta en la Radiación , Ratones , Ratones Desnudos , Trasplante de Neoplasias , Trasplante HeterólogoRESUMEN
Differentiation between viable myocardium and scar tissue in segments with abnormal contraction has important consequences in the clinical management of patients with coronary artery disease. Positron emission tomography (PET) can identify viable tissue using 18F-fluorodeoxyglucose (FDG). However, application of PET for daily routine is limited. In this study, FDG uptake was visualized with single photon emission computed tomography (SPECT) and compared with regional perfusion assessed with thallium-201 (201Tl) SPECT. The scintigraphic findings were related to regional wall motion determined with two-dimensional echocardiography. Patients (n = 9) with wall motion abnormalities underwent FDG SPECT and resting 201Tl SPECT. To control the metabolic status patients were studied with a hyperinsulinaemic euglycemic clamp during FDG SPECT. Analysis of reconstructed data was performed visually and semiquantitatively using circumferential profiles. High-quality images were obtained. Eight 201Tl defects showed concordantly decreased FDG uptake (metabolism-perfusion matches) indicating scarred tissue, whereas six regions of hypoperfusion demonstrated a relatively increased FDG uptake (mismatches), suggesting viable myocardium. Semiquantitative analysis confirmed visual findings. Mean 201Tl and FDG activities were not significantly different in matching defects. In mismatches the mean FDG activity was 81 +/- 11% vs 64 +/- 9% mean 201Tl activity (P < 0.0001). In four of six segments with increased FDG uptake, two-dimensional echo revealed hypokinesia. Seven of eight regions with a matching defect in contrast were akinetic. Thus, in the areas with a mismatch contractility was preserved. We conclude that FDG uptake can be visualized with SPECT. Furthermore, our preliminary observations suggest that this approach can identify viable tissue.
Asunto(s)
Desoxiglucosa/análogos & derivados , Radioisótopos de Flúor , Corazón/diagnóstico por imagen , Infarto del Miocardio/diagnóstico por imagen , Adulto , Anciano , Ecocardiografía , Estudios de Factibilidad , Fluorodesoxiglucosa F18 , Técnica de Clampeo de la Glucosa , Humanos , Masculino , Persona de Mediana Edad , Contracción Miocárdica , Infarto del Miocardio/metabolismo , Miocardio/metabolismo , Radioisótopos de Talio , Tomografía Computarizada de Emisión de Fotón ÚnicoRESUMEN
A detailed technical protocol is provided for reproducible and aseptical production of stable 186Re-monoclonal antibody conjugates. Labeled Mab E48 IgG and its F(ab')2 fragment which are promising candidates for radioimmunotherapy of squamous cell carcinoma of the head and neck were used for evaluation. S-benzoylmercaptoacetyltriglycine (S-benzoyl-MAG3) was used as a precursor. Rhenium-186-MAG3 was prepared via a unique solid-phase synthesis, after which known strategies for esterification and conjugation to Mab IgG/F(ab')2 were applied. The biodistribution of 186Re-E48 F(ab')2 in tumor-bearing nude mice was found to be comparable to that of analogously labeled 99mTc-E48 F(ab')2 or 131I-E48 F(ab')2, indicating that the intrinsic behavior of the antibody remains preserved when using this labeling technique. Radiolytic decomposition of 186Re-E48 IgG/F(ab')2 solutions of 10 mCi.ml-1 was effectively reduced by the antioxidant ascorbic acid. Upon increase of the Re-MAG3 molar amount, a conjugation of seven to eight Re-MAG3 molecules per Mab molecule was generally the maximum ratio that could chemically be obtained. Such a ratio did not impair the immunoreactivity or alter the in vivo biodistribution characteristics of the immunoconjugate, making this labeling procedure suitable for general clinical application.
Asunto(s)
Carcinoma de Células Escamosas/radioterapia , Neoplasias de Cabeza y Cuello/radioterapia , Radioinmunoterapia , Radioisótopos/uso terapéutico , Renio/uso terapéutico , Tecnecio Tc 99m Mertiatida/uso terapéutico , Animales , Anticuerpos Monoclonales , Femenino , Humanos , Ratones , Ratones Desnudos , Trasplante de NeoplasiasRESUMEN
Clinical oncology needs flexible techniques for routine monitoring of treatment response. We therefore compared planar 18F-fluorodeoxyglucose (FDG) with a conventional gamma-camera and a special collimator to 67Ga scintigraphy in 26 patients with malignant lymphoma during chemotherapy. The scintigraphic appearance of involved sites was essentially the same with both tracers: in patients eventually achieving complete remission, tracer distribution had normalized after two courses; high uptake reflected treatment failure; faint uptake was associated with variable outcome. For (re)staging, 67Ga may be preferable (higher contrast). To document the initial response, we performed FDG scintigraphy during the first course (n = 11). Effective treatment sharply reduced metabolic tumor activity within days and prior to volume response, whereas abnormal uptake persisted in treatment failure. Planar FDG scintigraphy may be a tool to assess the potentially prognostic initial response rate, preventing over-treatment and allowing a timely switch to more aggressive therapy.
Asunto(s)
Desoxiglucosa/análogos & derivados , Enfermedad de Hodgkin/diagnóstico por imagen , Linfoma no Hodgkin/diagnóstico por imagen , Fluorodesoxiglucosa F18 , Radioisótopos de Galio , Enfermedad de Hodgkin/tratamiento farmacológico , Humanos , Linfoma no Hodgkin/tratamiento farmacológico , Inducción de Remisión , Tomografía Computarizada de Emisión de Fotón ÚnicoRESUMEN
A class of new 5-fluorouracil (FU) analogues, the 5-fluoro-5,6-dihydro-6- alkoxy-uracils was synthesised with a modification at the 6-position of the pyrimidine ring. At this position the analogues have a hydroxy or alkoxy group of different chain lengths either in the cis- or trans-configuration. The antiproliferative effect of these compounds was tested on five cell lines of different origin. Generally, the analogues with a cis-configuration had a higher activity than those with a trans-configuration. The growth inhibitory effect of the compounds decreased with increasing alkoxy chain length, but the compound with a hydroxy group had the lowest growth inhibitory effect. One analogue, cis-5-F-5,6-dihydro-6-methoxy-uracil had a higher antiproliferative effect than FU in one of the cell lines. Effects on thymidylate synthase (TS), the possible target of these analogues, were evaluated by thymidine rescue of growth inhibition and incorporation of tritiated deoxyuridine (3H-UdR) into DNA. In solid tumour cell lines addition of TdR reversed the antiproliferative effect. Inhibition of TS in intact cells was determined by measuring 3H-UdR incorporation in two cell lines. The effect of cis-5-F-5,6-dihydro-6-methoxy-uracil on incorporation of 3H-UdR was 2- to 5-fold stronger than that of FU in both cell lines. All other compounds produced a higher 3H-UdR incorporation than FU both at equimolar and equi-toxic concentration. Concluding from these results we regard cis-5-F-5,6-dihydro-6-methoxy-uracil as the most promising FU analogue of this series, because of its higher antiproliferative activity than FU and marked inhibition of TS in intact cells.
Asunto(s)
Carcinoma de Células Escamosas/tratamiento farmacológico , Fluorouracilo/análogos & derivados , Fluorouracilo/uso terapéutico , Neoplasias Laríngeas/tratamiento farmacológico , Neoplasias de la Boca/tratamiento farmacológico , Timidilato Sintasa/metabolismo , Carcinoma de Células Escamosas/enzimología , Carcinoma de Células Escamosas/patología , División Celular/efectos de los fármacos , ADN de Neoplasias/metabolismo , Desoxiuridina/metabolismo , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Neoplasias Laríngeas/enzimología , Neoplasias Laríngeas/patología , Neoplasias de la Boca/enzimología , Neoplasias de la Boca/patología , Células Tumorales CultivadasRESUMEN
In our laboratory, a solid-phase synthesis of 186Re-mercaptoacetyltriglycine for reproducible and aseptic production of stable 186Re-monoclonal antibody conjugates was recently developed. Monoclonal antibody (MAb) E48 IgG, when labeled with 99mTc according to the same labeling procedure, was recently shown to be highly capable of detecting recurrent and metastatic disease in patients with head and neck squamous cell carcinoma. In the present study, MAb E48 was labeled with 186Re and tested for its capacity to eradicate established human head and neck squamous cell carcinoma xenografts growing s.c. in nude mice. Experimental groups received a single bolus injection of 200 [number of mice (n) = 6, number of tumors (t) = 11], 400 (n = 6, t = 11), 500 (n = 6, t = 12), or 600 (n = 5, t = 9) microCi 186Re-labeled MAb E48 IgG; control animals were given diluent (n = 4, t = 8). In the 200 microCi group, 5 of 11 tumors showed regression while the remaining tumors showed a decreased growth rate. In the other treatment groups, all tumors regressed. In all treatment groups, remissions were observed (no regrowth within 4 months after injection). The number of remissions in the 200, 400, 500, and 600 microCi group were 2 of 11 (18.2%), 3 of 11 (27.3%), 6 of 12 (50%), and 3 of 9 tumors (33.3%), respectively. In comparison with the median tumor volume doubling time of the controls, the tumor volume doubling time in the remaining tumors in the groups receiving 200, 400, 500, or 600 microCi was increased 5.5-, 7.8-, 8.7-, and 11.3-fold, respectively. Dosimetry was based on the biodistribution of 200 microCi 186Re-labeled MAb E48 IgG. In the group receiving 600 microCi, the absorbed cumulative radiation dose was 3432 cGy for tumor and 1356 cGy for blood. In other tissues, the accumulated dose was < 17% of the dose delivered to tumor. The whole-body dose was 11-fold lower than the dose delivered to tumor. Apparent toxicity was limited to weight loss, which did not exceed 12% and which returned to control levels within 2 weeks. No treatment-related deaths occurred. These data suggest radioimmunotherapy with 186Re-labeled MAb E48 IgG to be a feasible approach for the treatment of head and neck cancer.
Asunto(s)
Anticuerpos Monoclonales/uso terapéutico , Carcinoma de Células Escamosas/radioterapia , Neoplasias de Cabeza y Cuello/radioterapia , Inmunoglobulina G/uso terapéutico , Radioinmunoterapia , Radioisótopos/uso terapéutico , Renio/uso terapéutico , Animales , Femenino , Humanos , Ratones , Trasplante de Neoplasias , Dosificación Radioterapéutica , Trasplante HeterólogoRESUMEN
The diagnostic value of 99mTc-labeled monoclonal antibody E48 F(ab')2 (750 MBq, 1 mg) was evaluated in 10 patients with a histologically proven squamous cell carcinoma of the head and neck and with clinical evidence of cervical lymph node involvement. Preoperative findings on lymph node status obtained by radioimmunoscintigraphy (RIS), computerized tomography, magnetic resonance imaging, and palpation were defined per side (left and/or right side of the neck) as well as per lymph node level (I through V) and compared with the histopathological outcome of the neck dissection specimen. In 10 patients, all 8 known tumors at the primary site were detected by RIS. Furthermore, RIS was correct in 13 of 13 tumor involved neck sides and in 17 of 20 tumor involved lymph node levels. False-negative observations comprised 3 levels containing tumor deposits smaller than 1 cm in diameter, 2 of which were not detected by any other diagnostic modality. Palpation, computerized tomography, and magnetic resonance imaging were correct in, respectively, 13, 15, and 15 of the 20 tumor involved levels. There were 2 false-positive observations with monoclonal antibody E48 and 3 with palpation. No false-positive detections occurred with computerized tomography or magnetic resonance imaging. In two of the patients, RIS provided clinically important information which was not provided by any other diagnostic method. In one patient, recurrence of laryngeal carcinoma was established at the primary site after previous radiotherapy. In another patient, bilateral instead of unilateral lymph node involvement became apparent. These preliminary data indicate that radioimmunoscintigraphy with monoclonal antibody E48 may be helpful in the diagnosis of metastatic and recurrent head and neck cancer.
Asunto(s)
Anticuerpos Monoclonales , Carcinoma de Células Escamosas/diagnóstico por imagen , Neoplasias de Cabeza y Cuello/diagnóstico por imagen , Fragmentos Fab de Inmunoglobulinas , Tecnecio , Adolescente , Adulto , Anciano , Carcinoma de Células Escamosas/patología , Femenino , Neoplasias de Cabeza y Cuello/patología , Humanos , Metástasis Linfática , Masculino , Persona de Mediana Edad , Radioinmunodetección , Tomografía Computarizada de Emisión de Fotón ÚnicoRESUMEN
The in vitro growth inhibitory activity of eight novel 5-fluorinated uracil nucleosides was assessed in four human tumour cell lines, one of colon and three of head and neck squamous cell origin. These compounds are ribose or deoxyribose sugars with an acetoxy or an hydroxyl-group at the 6-position in the uracil part of the molecule, and their respective diastereoisomers. Antiproliferative effects were tested in an automated microculture assay based on the reduction of a tetrazolium dye, the MTT assay. Using a continuous drug exposure for four days, all novel nucleosides were more potent inhibitors of cell growth than 5-fluorouracil (5-FU). Most drugs were very active, having an IC50 value at least 10 fold lower than that of 5-FU, and this was consistently found for all cell lines. The 6-acetoxy compounds were generally more active than the compounds with a hydroxyl-group at the 6-position, while diastereoisomerism did not seem to influence the antiproliferative effect. Their capacity to inhibit the incorporation of tritiated deoxyuridine into DNA, which reflects the inhibition of thymidylate synthase, was measured in a short term assay. When tested at a concentration of 10(-6) mol/l, most of the compounds were found to block this incorporation more efficiently than 5-FU.
Asunto(s)
Neoplasias del Colon/metabolismo , Desoxiuridina/farmacología , Neoplasias de Cabeza y Cuello/metabolismo , ADN/biosíntesis , Desoxiuridina/análogos & derivados , Desoxiuridina/metabolismo , Fluorouracilo/metabolismo , Fluorouracilo/farmacología , Humanos , Mitosis/efectos de los fármacos , Estereoisomerismo , Células Tumorales Cultivadas/metabolismoRESUMEN
In a study investigating the usefulness of 5-fluorouracil labelled with fluorine 18 [( 18F]-5-FU) in cancer chemotherapy, the tissue distribution of the radiolabel was determined in mice at 2, 4 and 6 h after administration by varying several parameters such as the mode of administration, the strain of mouse, the presence of a tumour and the total dose of 5-FU. The tissue distribution of fluorine 18 after i.p. injection pointed to an altered behaviour of the drug and/or its metabolites when compared with values obtained after i.v. injection, but no difference was found in the accumulation of radiolabel in the tumour. A comparison of non-tumour-bearing BALB/c and C57Bl/6 mice revealed that the latter showed a higher radiolabel accumulation of the drug and its metabolites in the liver, kidney, intestines and coecum (P less than 0.05 at 2 and 4 h). In tumour-bearing mice, especially at 2 h, the tissue accumulation of radiolabel was found to be significantly higher than in non-tumour-bearing controls (in BALB/c mice bearing colon 26 carcinoma, P less than 0.05 for all tissues; in C57Bl/6 mice bearing colon 38 carcinoma, P less than 0.05 for the blood, lung, liver, kidney, large intestines, coecum and muscle). Finally, a comparison of injections of a tracer dose of [18F]-5-FU (2.5 mg/kg) vs a therapeutic dose (100 mg/kg) revealed only small differences in the accumulation of fluorine 18 in the liver and kidney.