This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by van Schaijk, F. G. Articles by Boerman, O. C. Search for Related Content PubMed PubMed Citation Articles by van Schaijk, F. G. Articles by Boerman, O. C.

Pretargeting with Labeled Bivalent Peptides Allowing the Use of Four Radionuclides

¹¹¹In, ¹³¹I, ^99mTc, and ¹⁸⁸Re¹

University Medical Center Nijmegen, Nijmegen, the Netherlands [F. G. v. S., E. O., A. C. S., W. J. G. O., F. H. M. C., O. C. B.], and Immunomedics, Inc., Morris Plains, New Jersey 07950 [W. J. M., G. L. G., D. M. G.]

	ABSTRACT

Top ABSTRACT Introduction Materials and Methods Results Discussion REFERENCES

 
Purpose: The therapeutic effect of directly labeled antibodies in solid tumors is limited, mainly due to the relatively low uptake of the radiolabeled antibody in tumors as compared with their blood level. In previous studies, we have shown that renal cell carcinoma (RCC) can be targeted very effectively with the ¹¹¹In-labeled bivalent peptide di-diethylenetriamminepentaacetic acid diDTPA-FKYK, after pretargeting the tumor with a bispecific antibody. In this study, we further developed this pretargeting approach for radioimmunotherapy of renal cell cancer.

Experimental Design: Pretargeting with the biologically produced anti-RCC x anti-DTPA bispecific monoclonal antibody (bsMAb G250xDTIn1) was tested in mice with SK-RC-52 RCC tumors. Tumors were pretargeted with 15 µg of bispecific monoclonal antibody G250xDTIn1, and 24 h later, mice received 6 ng of the radiolabeled bivalent peptide. Two different peptides were used: (a) diDTPA-FKYK labeled with ¹¹¹In or ¹³¹I; and (b) thiosemicarbonylglyoxylcysteinyl-diDTPA(In)-KYKK labeled with ^99mTc or ¹⁸⁸Re. Mice were killed 6, 24, 48, and 72 h postinjection (p.i.), and biodistribution of the radiolabel was determined.

Results: The ¹¹¹In-labeled peptide showed excellent tumor uptake [42.6 ± 7.3% injected dose/gram (ID/g) at 6 h p.i. and 25.6 ± 7.7% ID/g at 72 h p.i.] and tumor:blood ratios (700 at 72 h p.i.). The specific tumor targeting of ¹⁸⁸Re- and ^99mTc-labeled peptides was similar (20–25% ID/g, 6 h p.i.). However, the uptake and the retention in the tumor of the ^99mTc- and ¹⁸⁸Re-labeled peptide were significantly lower than those of the ¹¹¹In-labeled peptide. Tumor uptake of the ¹³¹I-labeled peptide was significantly lower as compared with the other three radiolabeled peptides; furthermore, an almost complete washout of the radiolabel from the tumor over time was observed (14.5 ± 4.9% ID/g at 6 h p.i. and 0.33 ± 0.15% ID/g at 72 h p.i.).

Conclusions: Using a newly developed bivalent peptide, this pretargeting approach can now be used for targeting with the matched pair ¹⁸⁸Re and ^99mTc.

	Introduction

Top ABSTRACT Introduction Materials and Methods Results Discussion REFERENCES

 
MAbs³ against tumor-associated antigens can be applied as delivery vehicles for radionuclides to visualize tumors or treat tumors [RIT (1, 2, 3) ]. The specificity of MAbs for tumor-associated antigens can be exploited to direct radionuclides selectively to tumor cells after systemic administration. Whereas radioimmunoscintigraphy was found to be suitable for detection of a wide variety of tumors (4) , RIT has caused mainly objective therapeutic responses in patients with relative radiosensitive hematological tumors (5) . In patients with solid tumors, RIT has been less effective, mainly due to insufficient uptake of the labeled antibody in the tumor (6) . However, RIT may be suitable to treat micrometastatic lesions after resection of the primary tumor. The relatively long circulation time of the radiolabeled antibodies in the circulation exposes nontumor tissues to relatively high radiation doses, thereby limiting the total activity dose that can be administered.

In 1986, Goodwin et al. (7) proposed to separate the administration of the MAb and the radioactive compound. In these so-called pretargeting approaches, the long-circulating nonlabeled MAb is administered first to allow specific localization in the tumor and clearance of the antibody from the blood. Thereafter, a fast-clearing radiolabeled hapten is injected. Various studies have confirmed the adequacy of this pretargeting strategy: tumor targeting comparable with the tumor targeting using directly labeled antibodies was achieved. Additionally, dramatic improvement of the T/B ratios was achieved as early as 1 h p.i. of the radiolabeled peptide (8, 9, 10, 11, 12) .

In previous studies, we have shown that the use of a bivalent peptide (substituted with two ¹¹¹In-labeled DTPA moieties) significantly improved tumor targeting as compared with a monovalent hapten (8) . This is most likely due to the affinity enhancement system (13) : by the formation of a bridge between two adjacent bispecific antibodies bound to the cell surface and one bivalent peptide, the peptide is more avidly bound to the cell surface. It has been postulated that the bivalent complex that is formed on the tumor cell surface is efficiently internalized, contributing to the more efficient accumulation of the radiolabeled bivalent peptide in the target cell. For scintigraphic applications, excellent tumor uptake was achieved (8) , but unfortunately, the yttrium-labeled bivalent peptide, suitable for therapy, proved unstable. Moreover, the affinity of the DTPA(In) recognition site of the bispecific antibody for the ⁹⁰Y-labeled DTPA is a factor 100 lower compared with the ¹¹¹In-labeled DTPA (14) . Therefore, we developed a two-step pretargeting strategy for RIT, using a radiolabeled bivalent peptide that can be labeled with both -emitters (imaging) as well as ß-emitters (therapy). The bispecific antibody recognizes both the G250 antigen, which is abundantly expressed on the cell surface of RCC, and an indium-labeled DTPA chelate (bsMAb G250xDTIn1). We investigated two bivalent peptides labeled with various radionuclides, transforming the strategy from a diagnostic approach using -emitters (¹¹¹In and ^99mTc) to a therapeutic approach using ß-emitters (¹³¹I and ¹⁸⁸Re).

	Materials and Methods

Top ABSTRACT Introduction Materials and Methods Results Discussion REFERENCES

 
bsMAb
The characteristics of MAb anti-G250 (IgG1), directed against the RCC-associated antigen G250, recently identified as carbonic anhydrase IX (MN/CA IX), have been described elsewhere (15 , 16) . The G250 antigen is expressed in virtually all clear cell RCCs. In normal tissues, G250 expression is restricted to gastric mucosal cells [cells of the small intestines and cells of the larger bile ducts (17) ].

The MAb anti-DTPA(In) (IgG2a) specifically recognizes In-labeled DTPA (14) . The production of bispecific antibody producing quadroma cells and the characterization and purification of the bsMAb anti-RCC x anti-DTPA-In (G250xDTIn1) have been described in detail elsewhere (14) .

Bivalent Peptides
IMP156.
The backbone of this peptide consists of four amino acids: phenylalanine; lysine; tyrosine; and lysine. The -amino group of each Lys residue was used to attach DTPA to obtain a bivalent peptide for the pretargeting approach as described by Gruaz-Guyon et al. (10) . To circumvent exo-peptidase activity in the circulation, the NH₂ terminus of the peptide was acetylated, and the COOH terminus was amidated. This bivalent peptide, Ac-Phe-Lys(DTPA)-Tyr-Lys(DTPA)-NH₂ [molecular weight 1377], was prepared by solid-phase synthesis and formulated in a lyophilized labeling kit, containing 11 µg of diDTPA-FKYK, 0.05 g of 2-hydroxypropyl-ß-cyclodextrin, and 0.0044 g of citrate (pH 4.2).

IMP192.
In this tetrapeptide, two lysine residues are conjugated with DTPA, and an additional chelate was conjugated to the COOH-terminal lysine residue Ac-Lys(DTPA)-Tyr-Lys(DTPA)-Lys(TscGC)-NH₂ [molecular weight 1590], where TscGC is thiosemicarbonylglyoxylcysteinyl. This peptide was formulated in two lyophilized labeling kits: a ^99mTc labeling kit containing 40 µg of peptide, 100 µg of SnCl₂, 1 mg of 2,5-dihydroxybenzoic acid, 10% 2-hydroxypropyl-ß-cyclodextrin, 200 mM glucoheptonate, 21 mM acetate (pH 5.3), and 6 molar equivalents of InCl₃; and a ¹⁸⁸Re labeling kit containing 40 µg of peptide, 8 mg of ascorbic acid, 10% 2-hydroxypropyl-ß-cyclodextrin, 6 molar equivalents of InCl₃, 166 mM glucoheptonate, 42 mM acetate (pH 4.4), and 1.32 mg of SnCl₂.

Radiolabeling
The minimum RCP of the labeled peptides used in these studies was set at 95%.

¹¹¹In-diDTPA.
Eleven µg of lyophilized diDTPA-FKYK (IMP156) were reconstituted with 1 ml of water. To 15 µl of the peptide solution, 63 µl of 40 mM HCl, 375 µl of H₂O, and 1.5 mCi of ¹¹¹InCl₃ (Tyco Health Care, Petten, the Netherlands) were added, and the reaction mixture was incubated for 60 min at room temperature. The RCP was determined by ITLC on silica gel strips with methanol:water (55:45) or citrate buffer (pH 6.0) as the mobile phase. When the RCP exceeded 95%, a 3-fold molar excess of InCl₃ was added to saturate the remaining DTPA chelates with stable In³⁺.

¹³¹I-diDTPA.
The chloramine-T method was used to radioiodinate IMP156. To 1.0 µg of diDTPA-FKYK, 15 µl of chloramine T (1.82 mg/ml) and 3.7 mCi of ¹³¹I were added. After a 2-min incubation at room temperature, the reaction was stopped by adding 100 µl of sodium metabisulphite (3.37 mg/ml). The DTPA moieties were saturated with a 3-fold molar excess of InCl₃. The solution was loaded on a C-18 Seppak cartridge (Waters, Milford, MA), washed with 10 ml of water, and eluted with 90% methanol. The RCP of the 90% methanol-eluted samples was determined both by ITLC on silica gel strips with citrate buffer (pH 6.0) as mobile phase and by using reverse-phase high-performance liquid chromatography on an Agilent 1100 series liquid chromatography system (Agilent Technologies, Palo Alto, CA). A Zorbax Rx-C18 column (5 µm, 4.6 x 250 mm) with a flow rate of 1 ml/min was used with a gradient from 100% 0.1% trifluoroacetic acid to 100% acetonitril within 20 min. Radiolabeled peptides were detected with an in-line Radiomatic A-500 series flow detector (Canberra-Packard, Meriden, CT).

^99mTc-diDTPA.
To a ^99mTc labeling kit containing 8 µg of lyophilized IMP192, 70 mCi of pertechnetate (^99mTcO₄^-) were added. Pertechnetate was obtained from an Ultratechnekow FM (Mo99/Tc99m) generator (Tyco Health Care). The reaction mixture was incubated for 10 min at room temperature, followed by a 30-min incubation at 100°C. The RCP was determined by ITLC on silica gel strips with saturated sodium chloride as the mobile phase. When the RCP was <95%, the labeled peptide was purified on a 10-ml gel filtration column (Biogel P-2; Bio-Rad, Hercules, CA).

¹⁸⁸Re-diDTPA.
¹⁸⁸Re was obtained from an in-house ¹⁸⁸W/¹⁸⁸Re generator (Oak Ridge National Laboratory, Oak Ridge, TN). After eluting the generator with 0.3 M NH₄OAc, approximately 20 ml of perrhenate eluate (160 mCi) were concentrated as described by Guhlke et al. (18) , with minor modifications. Briefly, the ¹⁸⁸ReO₄^- eluate was applied on a set of two cation exchange cartridges (IC-H-plus; Alltech, Deerfield, IL) at a flow of 0.4 ml/min. Fractions of 1 ml were collected. Fractions with a pH <2 were pooled and applied onto a QMA-light cartridge (anion exchange resin; Waters). The cartridge was washed with 10 ml of demineralized water, and the ¹⁸⁸ReO₄^- was eluted from the cartridge with a small volume of saline. Fractions (0.5 ml) were collected, and their radioactive content was determined in a dose calibrator (Capintec CRC-15R, Ramsey, NJ).

To a ¹⁸⁸Re labeling kit containing 8 µg of lyophilized IMP192 peptide, 154 µl of concentrated ¹⁸⁸Re solution (173 mCi/ml) were added. The reaction mixture was incubated for 10 min at room temperature, followed by a 60-min incubation at 100°C. The RCP was determined by ITLC on silica gel strips with saturated NaCl as mobile phase. The RCP of the ¹⁸⁸Re-labeled peptide exceeded 95%.

Biodistribution Study
The studies were approved by the local animal welfare committee and performed in accordance with its guidelines.

The biodistribution of the radiolabeled peptides was determined in female BALB/c nu/nu mice with s.c. SK-RC-52 tumors. Briefly, 6–8-week-old athymic mice were s.c. injected with SK-RC-52 cells (1.5 x 10⁶ cells/200 µl). Two to 4 weeks later, when the tumors were palpable, the biodistribution studies were initiated. All reagents were injected i.v. via the tail vein in a volume of 200 µl. Mice received 15 µg of bsMAb, and 24 h later, the radiolabeled peptide was administered. At various time points after injection of the radiolabeled peptides, mice were killed by CO₂ asphyxiation, and blood was obtained by heart puncture. The tissues (tumor, muscle, lung, spleen, kidney, liver, and small intestine) were dissected and weighed, and their radioactivity was counted in a gamma counter (Wallac wizard 3'' 1480 automatic gamma counter; Wallac, Turku, Finland). To permit calculation of the radioactive uptake in each organ as a fraction of the injected dose, an aliquot of the injection dose was counted simultaneously. Results were expressed in %ID/g. All groups consisted of four or five mice.

Statistical Analysis
All mean values are given ± SD. Statistical analysis was performed using the unpaired t test when two groups were analyzed, and one-way ANOVA was used when more than two groups were analyzed. The level of significance was set at P < 0.05.

	Results

Top ABSTRACT Introduction Materials and Methods Results Discussion REFERENCES

 
Optimization of the Doses of the Reagents.
To determine the optimum dose of bsMAb G250xDTIn1, SK-RC-52 tumor-bearing mice received i.v. injection of various doses of the bsMAb [0.1, 0.2, 0.5, or 1 nmol (15, 30, 75, or 150 µg, respectively)]. Twenty-four h later, 3.8 pmol (6 ng) of ^99mTc-labeled IMP192 peptide were administered. Six h after injection of the radiolabeled peptide, mice were killed, and the biodistribution of the radiolabel was determined (Table 1) . Highest uptake in the tumor was obtained at 0.1 and 0.2 nmol of bsMAb. Tumor uptake with these two low doses was not significantly different (26.3 ± 9.5% and 37.0 ± 19.4% ID/g, respectively; P = 0.30). At higher doses of bsMAb, the uptake of the radiolabel in the tumor was significantly lower. In addition, at the higher protein dose (>0.2 nmol), the radioactivity in the blood and in the normal tissues was more than 2-fold higher compared with the lower bsMAb doses (blood levels: 6.8 ± 0.6% ID/g at 0.1 nmol of bsMAb and 15.5 ± 1.8% ID/g at 1.0 nmol of bsMAb).

Biodistribution of ¹³¹I-IMP156 and ¹³¹I-IMP192 in Mice Pretargeted with bsMAb.
To investigate whether differences in peptide composition and the presence of an extra TscGC chelate in IMP192 affected the biodistribution of the peptide, the biodistribution of the two radiolabeled peptides (IMP156 and IMP192) was determined in mice with pretargeted SK-RC-52 tumors (Fig. 1) . The biodistribution, including tumor uptake of the two bivalent peptides, was highly similar. Only the blood levels of the two peptides were significantly different at all time points (P < 0.007). At each time point, the blood levels of the IMP192 peptide were 1.5x higher than the blood levels of IMP156.

View larger version (21K): [in this window] [in a new window]   Fig. 1. Biodistribution of s.c. SK-RC-52 tumor-bearing mice, pretargeted with 0.1 nmol of bsMAb G250xDTIn1 followed by administration, 24 h later, of 131I-IMP156 (A) or 131I-IMP192 (B). Mice were killed at various time points after injection of the radiolabel, and the biodistribution of the radiolabel was determined. At all time points, each group consisted of five mice. Uptake is expressed as %ID/g.

Twenty-four h after pretargeting SK-RC-52 RCC with 0.1 nmol of bsMAb G250xDTIn1, mice received i.v. injection with 3.8 pmol of each of the radiolabeled peptides. The results of the biodistribution studies are summarized in Table 3 and Fig. 2 .

View larger version (14K): [in this window] [in a new window]   Fig. 2. Biodistribution of 111In-IMP156, 188Re-IMP192, 99mTc-IMP192, and 131I-IMP156. s.c. SK-RC-52 tumors were pretargeted with 0.1 nmol of bsMAb G250xDTIn1, followed by administration of 3.8 pmol of the peptides 24 h later. Mice were killed 6, 24, 48, and 72 h p.i., and the biodistribution of the radiolabels was determined. Uptake is expressed as %ID/g.

The tumor uptake of the ¹³¹I-labeled IMP156 was considerably lower at 6 h p.i. From 6 h p.i. onward, the radiolabel cleared from the tumor (14.5 ± 4.9% ID/g at 6 h p.i., decreasing to 0.3 ± 0.2% ID/g at 72 h p.i.). The radioactivity in the blood and the normal organs decreased very rapidly, similar to the ¹¹¹In-labeled IMP156.

The biodistribution of ^99mTc-IMP192 was very similar to that of ¹⁸⁸Re-IMP192 at 6 and 24 h p.i. From 24 h p.i. onward, the uptake of the ¹⁸⁸Re-labeled peptide was stable at a level of 8.1 ± 3.8% ID/g. Compared with the ¹¹¹In-labeled peptide, the tumor uptake of the ^99mTc- and ¹⁸⁸Re-labeled IMP192 peptides was significantly lower at all time points (P < 0.02). Conversely, at all time points, tumor uptake of the ^99mTc- and ¹⁸⁸Re-labeled IMP192 peptides was significantly higher than that obtained with the ¹³¹I-labeled peptide (P < 0.03). In addition, the uptake in the kidney is remarkably low, suggesting that the bivalent tetrapeptides used in these studies are inefficiently reabsorbed in the renal tubular cells.

	Discussion

Top ABSTRACT Introduction Materials and Methods Results Discussion REFERENCES

 
For the development of an effective pretargeting strategy for RIT, the use of ß-emitting radionuclides is required. In previous studies, we showed that with the pretargeting approach, based on the use of a biologically produced anti-RCC x anti-DTPA bispecific antibody, RCC tumors could be targeted very effectively with an ¹¹¹In-labeled bivalent peptide (8) . In the present study, we compared the biodistribution of four different radionuclides (¹¹¹In, ¹³¹I, ¹⁸⁸Re, and ^99mTc) labeled to different bivalent peptides (IMP156 or IMP192) to develop a two-step pretargeting approach suitable for RIT using ß-emitting radionuclides.

In earlier studies, we have investigated the use of yttrium as a ß-emitting radionuclide in this strategy (14) . For therapeutic application, this radionuclide has excellent features [⁹⁰Y: t_1/2 = 64.1 h; ß_max = 2.28 MeV (100%); Ref. 19 ]. However, unlike ¹¹¹In, ⁹⁰Y is incorporated in the bone after release from the chelate. Unfortunately, although the peptide IMP156 can be labeled with yttrium, the compound is not stable in serum. Moreover, the affinity of the bispecific antibody for ⁹⁰Y-labeled DTPA was at least 100x lower compared with ¹¹¹In-labeled DTPA (14) . Consequently no specific localization of ⁹⁰Y-labeled IMP156 in the tumor was observed (14) .

In the present study, the highest tumor uptake in the SK-RC-52 mouse model was achieved with the ¹¹¹In-labeled bivalent peptide IMP156. After 6 h p.i., tumor uptake of this peptide (42.6 ± 7.3% ID/g) slightly decreased (30.5 ± 15.0% ID/g at 24 h p.i.), and thereafter, the tumor uptake stabilized. This peptide was well retained in the tumor.

The newly synthesized peptide IMP192 can be labeled very efficiently with ¹⁸⁸Re, a ß-emitter, or with ^99mTc, a -emitter. ¹⁸⁸Re has excellent characteristics for therapeutic application (20) : high ß_max energy emission (2.12 MeV), comparable with ⁹⁰Y, and 140 keV -radiation (10% abundance), allowing scintigraphic imaging of therapeutic doses. The half-life (t_1/2 = 17 h) is considered too short for use with directly labeled antibodies, but it can be used in this two-step approach. ^99mTc has chemical properties similar to ¹⁸⁸Re. ^99mTc and ¹⁸⁸Re form a so-called "matched pair": ^99mTc can be used for imaging to predict the targeting and dosimetry of therapeutic doses of ¹⁸⁸Re. Both radionuclides were labeled to the peptide IMP192 via a TscGC chelate as described by Karacay et al. (9) . The biodistribution of the ^99mTc-labeled diDTPA showed similar tumor uptake characteristics as the ¹⁸⁸Re-labeled peptide, confirming the matched pair concept.

The order of tumor retention was ¹¹¹In > ¹⁸⁸Re/^99mTc > ¹³¹I. ¹³¹I was readily lost from the tumor, whereas the uptake of ¹⁸⁸Re in the tumor decreased from approximately 21% ID/g (6 h p.i.) to approximately 8% ID/g (24–72 h p.i.). Karacay et al. (9) performed similar experiments in vivo with ¹⁸⁸Re-labeled IMP192 using mice with GW-39 human colonic cancer xenografts and a chemically linked bispecific F(ab')₂ fragment (F6 x m734). Their biodistribution results with the ¹⁸⁸Re-labeled peptide were very similar to ours (tumor uptake: 19.3 ± 4.2% ID/g at 3 h p.i. to 6.5 ± 2.6% ID/g at 72 h p.i.). In contrast, Gestin et al. (11) showed that the uptake and retention of a ¹²⁵I-labeled peptide exceeded the values obtained with the ¹⁸⁸Re-labeled peptide. This difference is most likely caused by the use of different peptides (octapeptides) and/or a non-MAb-internalizing tumor model (LS174-T).

The uptake and retention of the ¹³¹I- and ¹¹¹In-labeled peptide IMP156 were markedly different in our model. It is generally known that ¹¹¹In is better retained in the tumor after internalization than the nonmetal ¹³¹I. The rapid clearance of the ¹³¹I-labeled IMP156 peptide from the tumor suggests that the labeled IMP156 peptide, once bound to the cell surface of SK-RC-52 tumor cells, is internalized by the target cell.

In vitro, Shih et al. (21) , using directly labeled MAbs, observed a similar washout of ¹²⁵I- and ¹⁸⁸Re-labeled antibodies (¹⁸⁸Re was conjugated to thiol groups of mildly reduced antibodies, and for labeling the antibody with ¹²⁵I, the chloramine-T method was used). Only 10% of the ¹⁸⁸Re and ¹²⁵I activity that was initially targeted to the tumor cells was retained in the cells after 72 h. In our study as well as the study of Karacay et al. (9) , the nonresidualizing radionuclide ¹⁸⁸Re, incorporated in a TscGC chelate, showed an improved tumor retention (compared with targeting of ¹²⁵I- or ¹³¹I-labeled peptides) that could possibly be due to the use of the TscGC chelate. This suggests that the TscGC chelate gives ¹⁸⁸Re as well as ^99mTc residualizing properties.

Despite successful specific uptake of these radiolabeled peptides using the pretargeting approach, the retention of ß-emitters in the tumor is suboptimal and can be further improved. We now aim to make our pretargeting strategy suitable for use of residualizing radionuclides such as ¹⁷⁷Lu or ⁹⁰Y.

These studies showed that the pretargeting approach can be used for RIT. Due to lack of retention in the tumor, the ¹³¹I-labeled peptide is not suitable. IMP192 labeled with ¹⁸⁸Re or ^99mTc can be used as a matched pair. The use of residualizing radionuclides such as ¹⁷⁷Lu and ⁹⁰Y in this two-step pretargeting approach could further improve the accumulation and retention of the ß-emitting radiolabel in the tumor.

	ACKNOWLEDGMENTS

 
We thank G. Grutters, H. Eijkholt, and B. Lemmers (University of Nijmegen, Central Animal Laboratory) for technical assistance in the animal experiments.

	FOOTNOTES

 
¹ Presented at the "Ninth Conference on Cancer Therapy with Antibodies and Immunoconjugates," October 24–26, 2002, Princeton, NJ. This work was supported by Research Grant KUN 2000-2306 from the Dutch Cancer Society.

² To whom requests for reprints should be addressed, at Department of Nuclear Medicine, University Medical Center Nijmegen, P. O. Box 9101, 6500 HB Nijmegen, the Netherlands. Phone: 31-24-3613813; Fax: 31-24-3618942; E-mail: O.Boerman{at}nucmed.umcn.nl

³ The abbreviations used are: MAb, monoclonal antibody; bsMAb, bispecific MAb; DTIn1, indium-labeled DTPA; DTPA, diethylenetriamminepentaacetic acid; TscGC, thiosemicarbonylglyoxylcysteinyl group; RIT, radioimmunotherapy; p.i., postinjection; ID/g, injected dose/gram; T/B, tumor:blood; RCC, renal cell carcinoma; RCP, radiochemical purity; ITLC, instant thin-layer chromatography.

	REFERENCES

Top ABSTRACT Introduction Materials and Methods Results Discussion REFERENCES

 

1. Goldenberg D. M., DeLand F., Kim E., Bennett S., Primus F. J., van Nagell J. R., Estes N., DeSimone P., Rayburn P. Use of radiolabeled antibodies to carcinoembryonic antigen for the detection and localization of diverse cancers by external photoscanning. N. Engl. J. Med., 298: 1384-1386, 1978.[Abstract]
2. Goldenberg D. M. An introduction to the radioimmunodetection of cancer. Cancer Res., 40: 2957-2959, 1980.
3. Goldenberg D. M., Gaffar S. A., Bennett S. J., Beach J. L. Experimental radioimmunotherapy of a xenografted human colonic tumor (GW-39) producing carcinoembryonic antigen. Cancer Res., 41: 4354-4360, 1981.[Medline]
4. Knox S. J., Meredith R. F. Clinical radioimmunotherapy. Semin. Radiat. Oncol., 10: 73-93, 2000.[CrossRef][Medline]
5. Jurcic J. G., Scheinberg D. A. Radioimmunotherapy of hematological cancer: problems and progress. Clin. Cancer Res., 1: 1439-1446, 1995.[Medline]
6. Sharkey R. M., Pykett M. J., Siegel J. A., Alger E. A., Primus F. J., Goldenberg D. M. Radioimmunotherapy of the GW-39 human colonic tumor xenograft with ¹³¹I-labeled murine monoclonal antibody to carcinoembryonic antigen. Cancer Res., 47: 5672-5677, 1987.[Abstract/Free Full Text]
7. Goodwin D. A., Mears C. F., McTigue M., David G. S. Monoclonal antibody hapten radiopharmaceutical delivery. Nucl. Med. Commun., 7: 569-580, 1986.[Medline]
8. Boerman O. C., Kranenborg M. H., Oosterwijk E., Griffiths G. L., McBride W. J., Oyen W. J., de Weijert M., Oosterwijk-Wakka J., Hansen H. J., Corstens F. H. Pretargeting of renal cell carcinoma: improved tumor targeting with a bivalent chelate. Cancer Res., 59: 4400-4405, 1999.[Abstract/Free Full Text]
9. Karacay H., McBride W. J., Griffiths G. L., Sharkey R. M., Barbet J., Hansen H. J., Goldenberg D. M. Experimental pretargeting studies of cancer with a humanized anti-CEA x murine anti-[In-DTPA] bispecific antibody construct and a ^99mTc-/¹⁸⁸Re-labeled peptide. Bioconjug. Chem., 11: 842-854, 2000.[CrossRef][Medline]
10. Gruaz-Guyon A., Janevik-Ivanovska E., Raguin O., Labriolle-Vaylet C., Barbet J. Radiolabeled bivalent haptens for tumor immunodetection and radioimmunotherapy. Q. J. Nucl. Med., 45: 201-206, 2001.[Medline]
11. Gestin J. F., Loussouarn A., Bardies M., Gautherot E., Gruaz-Guyon A., Sai-Maurel C., Barbet J., Curtet C., Chatal J. F., Faivre-Chauvet A. Two-step targeting of xenografted colon carcinoma using a bispecific antibody and ¹⁸⁸Re-labeled bivalent hapten: biodistribution and dosimetry studies. J. Nucl. Med., 42: 146-153, 2001.[Abstract/Free Full Text]
12. Boerman O. C., Van Schaijk F. G., Oyen W. J. G., Corstens F. H. M. Pretargeted radioimmunotherapy of cancer: progress step-by-step. J. Nucl. Med., 44: 400-411, 2003.[Abstract/Free Full Text]
13. Barbet J., Kraeber-Bodere F., Vuillez J. P., Gautherot E., Rouvier E., Chatal J. F. Pretargeting with the affinity enhancement system for radioimmunotherapy. Cancer Biother. Radiopharm., 14: 153-166, 1999.[Medline]
14. Kranenborg M. H., Boerman O. C., Oosterwijk-Wakka J. C., de Weijert M. C., Corstens F. H., Oosterwijk E. Development and characterization of anti-renal cell carcinoma x antichelate bispecific monoclonal antibodies for two-phase targeting of renal cell carcinoma. Cancer Res., 55: 5864s-5867s, 1995.[Medline]
15. Pastorek J., Pastorekova S., Callebaut I., Mornon J. P., Zelnik V., Opavsky R., Zat’ovicova M., Liao S., Portetelle D., Stanbridge E. J., et al Cloning and characterization of MN, a human tumor-associated protein with a domain homologous to carbonic anhydrase and a putative helix-loop-helix DNA binding segment. Oncogene, 9: 2877-2888, 1994.[Medline]
16. Uemura H., Nakagawa Y., Yoshida K., Saga S., Yoshikawa K., Hirao Y., Oosterwijk E. MN/CA IX/G250 as a potential target for immunotherapy of renal cell carcinomas. Br. J. Cancer, 81: 741-746, 1999.[CrossRef][Medline]
17. Oosterwijk E., Ruiter D. J., Hoedemaeker P. J., Pauwels E. K., Jonas U., Zwartendijk J., Warnaar S. O. Monoclonal antibody G 250 recognizes a determinant present in renal-cell carcinoma and absent from normal kidney. Int. J. Cancer, 38: 489-494, 1986.[Medline]
18. Guhlke S., Beets A. L., Oetjen K., Mirzadeh S., Biersack H. J., Knapp F. F., Jr. Simple new method for effective concentration of ¹⁸⁸Re solutions from alumina-based ¹⁸⁸W-¹⁸⁸Re generator. J. Nucl. Med., 41: 1271-1278, 2000.[Abstract/Free Full Text]
19. Sharkey R. M., Motta-Hennessy C., Pawlyk D., Siegel J. A., Goldenberg D. M. Biodistribution and radiation dose estimates for yttrium- and iodine-labeled monoclonal antibody IgG and fragments in nude mice bearing human colonic tumor xenografts. Cancer Res., 50: 2330-2336, 1990.[Abstract/Free Full Text]
20. Griffiths G. L., Goldenberg D. M., Knapp F. F., Jr., Callahan A. P., Chang C. H., Hansen H. J. Direct radiolabeling of monoclonal antibodies with generator-produced rhenium-188 for radioimmunotherapy: labeling and animal biodistribution studies. Cancer Res., 51: 4594-4602, 1991.[Abstract/Free Full Text]
21. Shih L. B., Thorpe S. R., Griffiths G. L., Diril H., Ong G. L., Hansen H. J., Goldenberg D. M., Mattes M. J. The processing and fate of antibodies and their radiolabels bound to the surface of tumor cells in vitro: a comparison of nine radiolabels. J. Nucl. Med., 35: 899-908, 1994.[Abstract/Free Full Text]

This article has been cited by other articles:

				F. G. van Schaijk, E. Oosterwijk, A. C. Soede, M. Broekema, C. Frielink, W. J. McBride, D. M. Goldenberg, F. H.M. Corstens, and O. C. Boerman Pretargeting of Carcinoembryonic Antigen-Expressing Tumors with a Biologically Produced Bispecific Anticarcinoembryonic Antigen x Anti-Indium-Labeled Diethylenetriaminepentaacetic Acid Antibody Clin. Cancer Res., October 1, 2005; 11(19): 7130s - 7136s. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by van Schaijk, F. G. Articles by Boerman, O. C. Search for Related Content PubMed PubMed Citation Articles by van Schaijk, F. G. Articles by Boerman, O. C.