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Papers by David Colcher

Cancer Research, Aug 1, 1988

Four monoclonal antibodies (MoAbs) (35, 115, 17-1A, and B72.3) directed towards human carcinoma s... more Four monoclonal antibodies (MoAbs) (35, 115, 17-1A, and B72.3) directed towards human carcinoma surface antigens have been studied in athymic nude mice with LS174T, COI 12, or SW948 colon carcinoma xenografts or negative control melanoma (Ml-'.l -I ), lymphoma (Namalwa), and breast (MCF-7) carcinoma xenografts to evaluate the effects of antigenic heterogeneity and time after administration on localization and imaging. '"l-labeled 115 showed the highest uptake of any antibody in LS174T tumors. MoAbs 35 and B72.3 showed similar but lower levels of uptake in LS174T and COI 12 tumors, but B72.3 concentrated less in SW948 tumors. 17-1A showed the highest degree of accumulation in SW948 tumor xenografts. No specific uptake of the four anti-carcinoma MoAbs was observed in MEL-1, Namalwa, or MCF-7 xenografts. The specificity of the in viro tumor localization of the four anti-carcinoma MoAbs was confirmed by the low degree of accumulation of a control MoAb against influenza virus in LS174T tumors. Imaging studies with '"I-labeled colorectal cancer MoAbs showed specific uptake and reten tion in LS174T tumors, with progressive clearance from the whole body. The colorectal cancer MoAbs were compared for immunohistochemical binding against biopsies from patients with colorectal cancer and adjacent normal colonie tissue. Most colorectal cancer specimens showed moder ate to strong staining with the four MoAbs. The percentage of positive cells varied within and between tumors demonstrating antigenic hetero geneity. Absent to slight focal staining was seen with normal colon tissue. B72.3 showed the highest degree of staining specificity. This study indicates a difference in the immunohistochemical binding of a panel of MoAbs against biopsies of colon adenocarcinoma and a dependence of in vivo localization on the human colon cancer cell line used as target. This has important implications for future clinical diagnostic and therapeutic studies.

Cancer Research, Jul 1, 1987

Murine monoclonal antibodies (MAbs) reactive with distinct epitopes on carcinoembryonic antigen (... more Murine monoclonal antibodies (MAbs) reactive with distinct epitopes on carcinoembryonic antigen (CEA) have been analyzed systematically by radioimmunoassays, Western blotting, and immunohistochemical as says to define CEA expression in adenocarcinomas, benign lesions, and normal tissues of the stomach. Each of four COL-MAbs (COL-1, COL-4, COL-6, and COL-12) reacted preferentially with cell extracts of adenocarcinomas versus those of normal mucosae in solid-phase radioim munoassays. Using Western blotting analyses MAbs COL-1, COL-4, COL-6, and COL-12 detected only the M, 180,000 molecule character istic of CEA in adenocarcinoma of the stomach; no reactivity was observed in an extract of normal gastric mucosa. Antibody competition radioim munoassays were then carried out to define relations among COL-MAbs using '"I-radiolabeled MAbs, and nonradiolabeled MAbs as competitors. A spectrum of formalin-fixed, paraffin-embedded normal, benign, and malignant tissue sections of the stomach were examined for immunoreactivities with COL-MAbs using immunohistochemical assays to define whether the COL-MAbs were able to detect CEA expression in early foci of gastric carcinomas. All of the COL-MAbs generally demonstrated selective reactivities to adenocarcinomas (n = 40) versus benign lesions (n = 15) and normal mucosae (n = 6) of the stomach. From 72 to 100% of adenocarcinomas at early stage (n = 18) were reactive with the COL-MAbs, suggesting that these MAbs might serve as immunohistochemical diagnostic tools to detect early foci of gastric carcinoma. The data reported here indicate that the COL-MAbs can potentially be utilized as radioimmunological and immunohistochemical adjuncts to differentiate early adenocarcinomas from normal mucosae or benign lesions of the stomach on the basis of differential CEA expression. .

International Journal of Gastrointestinal Cancer, 1995

An adhesion factor, produced by the hamster pancreatic cancer cell line PC-1.0, was tested for it... more An adhesion factor, produced by the hamster pancreatic cancer cell line PC-1.0, was tested for its efficiency in promoting the in vitro adhesion of normal and tumor cells (pancreas, lung, kidney, colon, breast, skin, prostate, neuroblast, melanocyte) derived from human, monkey, bovine, hamster, and rat sources. Using a modification of the dimethylthyazol diphenyl tetrazolium (MTT) assay, the factor was found to induce adhesion in all cell lines in a dose-dependent manner. Although the effect was variously expressed, there was a statistically significant difference between the MTT absorbance of cells incubated in the presence or absence of the factor. Conditioned medium of each cell line tested showed significantly less adhesion effect than that produced by PC-1.0 cells. Because our previous study indicated that the adhesion factor produced by PC-1.0 cells differed from known growth factors and adhesion molecules including fibronectin, vibronectin, laminin, and collagen, it appears that PC-1.0 cells produce a novel adhesion factor that enhances adherence of normal and malignant cells of different species. this field have provided evidence for new adhesion factors and helped to identify families of known factors (8-10).

Methods in Enzymology, Feb 1, 1986

Journal of Nuclear Medicine, Oct 1, 2001

Radioimmunopharmaceutical agents enabling rapid high-resolution imaging, high tumor-to-background... more Radioimmunopharmaceutical agents enabling rapid high-resolution imaging, high tumor-to-background ratios, and minimal immunogenicity are being sought for cancer diagnosis and imaging. Genetic engineering techniques have allowed the design of single-chain Fv's (scFv's) of monoclonal antibodies (mAbs) recognizing tumor-associated antigens. These scFv's show good tumor targeting and biodistribution properties in vivo, indicating their potential as imaging agents when labeled with a suitable radionuclide. Methods: Divalent (sc(Fv) 2 ) and tetravalent ([sc(Fv) 2 ] 2 ) scFv's of mAb CC49 were evaluated for radioimmunolocalization of LS-174T colon carcinoma xenografts in athymic mice. scFv's were radiolabeled with 99m Tc by way of the bifunctional chelator succinimidyl-6-hydrazinonicotinate hydrochloride using tricine as the transchelator. The immunoreactivity and in vitro stability of the scFv's were analyzed after radiolabeling. Biodistribution and pharmacokinetic studies were performed to determine the tumor-targeting potential of the radiolabeled scFv's. Whole-mouse autoradiography illustrated the possible application of these 99m Tc-labeled multivalent scFv's for imaging. Results: The radiolabeling procedure gave Ն95% radiometal incorporation, with a specific activity of Ͼ74 MBq/mg scFv. In solid-phase radioimmunoassay, both sc(Fv) 2 and [sc(Fv) 2 ] 2 exhibited 75%-85% immunoreactivity, with nonspecific binding between 0.8% and 1.2%. Size-exclusion highperformance liquid chromatography showed sc(Fv) 2 as a 60-kDa protein and [sc(Fv) 2 ] 2 as a 120-kDa protein. Blood clearance studies showed the elimination half-life of 99m Tc-labeled sc(Fv) 2 as 144 min and that of [sc(Fv) 2 ] 2 as 307 min. Whole-body clearance studies confirmed the rapid elimination of scFv's, with half-lives of 184 Ϯ 19 min for sc(Fv) 2 and 265 Ϯ 39 min for [sc(Fv) 2 ] 2 (P Ͻ 0.001). At 6 h after administration, the tumor localization was 7.2 Ϯ 0.7 percentage injected dose per gram of tumor (%ID/g) for 99m Tc-sc(Fv) 2 . 99m Tc-[sc(Fv) 2 ] 2 showed a tumor uptake of 19.1 Ϯ 1.1 %ID/g at the same time; the amount of radioactivity in the tumors was 4-fold higher than in the spleen and kidneys and 2-fold higher than in the liver. Macroautoradiography performed at 6 and 16 h after administration clearly detected the tumor with both scFv's. Conclusion: 99m Tclabeled multivalent scFv's show good tumor-targeting characteristics and high radiolocalization indices (tumor-to-background ratio). These reagents, therefore, have the potential for use in clinical imaging studies of cancer in the field of nuclear medicine.

Journal of Nuclear Medicine, May 1, 1987

ost ofthe initial efforts in the use of radiolabeled MAbS as radiopharmaceuticals for the localiz... more ost ofthe initial efforts in the use of radiolabeled MAbS as radiopharmaceuticals for the localization of occult malignant tumors were focused in the iodides as the radionuclides of choice. These radionuclides have enabled successful targeting of tumors, both in experi mental models and in patients with a variety of diseases (1,2). The high-energy beta (toxicity considerations) and higher than optimal energy gamma emissions (in efficient for gamma imaging) as well as the apparent in vivo dehalogenation (3,4) may restrict the utility of iodine-l 3 1 in clinical trials. Strong chelating groups can be covalently attached to proteins and labeled with ReceivedApr. 22, 1986;revision accepted Sept. 10, 1986. radioactive metals. Indium-i 11 (â€ẫ €ẫ€˜In) with its lower energy gamma and lack of beta emissions is a better choice ofradionuclide for radiolocalization studies. The different labeling methodologies currently available to link chelates to proteins, using the cyclic anhydride (CA) (5) and mixed anhydride (MA) (6) derivatives of DTPA (diethylenetriaminepentaacetic acid), form pro tein-diethylenetriaminetetraacetic acid (DTTA) com plexes. When â€ẫ€ẫ€˜In is placed in these chelates, the re sulting complexes are kinetically and thermodynami cally unstable in vivo (7). Release of the â€ẫ€ẫ€˜In from the conjugates produces a continuous leakage of radio nuclide into the blood resulting in transport through transferrmnto the liver and other organs of the reticu loendothelial system. This liver uptake (8â€"1 1) poses a significant problem that drastically limits the utility of I 1â€˜Inin clinical trials since many carcinomas metastas 861

Journal of Virology, Mar 1, 1977

Radioactive 60-70S RNA from the mouse mammary tumor virus (MMTV) produced by the C3H mouse mammar... more Radioactive 60-70S RNA from the mouse mammary tumor virus (MMTV) produced by the C3H mouse mammary tumor cell line (Mm5mt) hybridized to a greater extent, and at a lower Cotj/2 value, to the DNA of C3H mammary tumor

ABSTRACT The authors have previously reported that monoclonal antibody B6.2 and its fragments lab... more ABSTRACT The authors have previously reported that monoclonal antibody B6.2 and its fragments labeled with I-125 selectively localizes in human breast tumor (bt) xeongrafts in nude mice. Herein the authors compare I-125 B6.2 and its fragments with regard to (a) in vitro binding to bt extracts and (b) blood clearance. Antibody B6.2 and fragments were labeled using iodogen and then incubated with cell extracts of a human bt metastasis to the liver (Met.173), MCF-7 bt line, and normal human liver. Scatchard analysis of the data revealed that I-125-B6.2 and its fragments bound to both breast tumors with affinity constants of the order of 10â¹Mâ»Â¹; no specific binding to normal liver was observed. The affinity constant for both divalent fragments was higher than that observed for the monovalent Fab' fragment. Serial sampling of blood from tumor bearing mice indicated that the blood clearance of F(ab')â was more rapid than IgG and that Fab' cleared considerably faster still. A comparison of the biodistribution at 0.1 and 5 ..mu..g protein per mouse suggests that with 1 gm tumors, lower doses do not necessarily result in better tumor-to-tissue ratios. When the blood clearance of I-125-B6.2 was compared to that of a non-specific IgG (MOPC), a much faster clearance of I-125 activity, significantly greater than that resultant from uptake in the tumor, was observed. Accelerated blood clearance may be due to selective catabolism of the specific antibody. When I-125 labeled B6.2 was injected into mice bearing breast and melanoma tumors, the thyroid uptake of I-125 activity was 2-3 times greater in the bt mice. The authors conclude that catabolism may be an important factor in determining the optimal radiolabel for immunoscintigraphy.

ABSTRACT Monoclonal antibody B6.2 is promising for the detection of breast cancers; it binds to &... more ABSTRACT Monoclonal antibody B6.2 is promising for the detection of breast cancers; it binds to >80% of human breast carcinoma (hbc) lines, its antigen is not seen in serum, and it localizes selectively in hbc xenografts in nude mice. The authors have studied the biokinetics of I-131 activity following injection of I-131-IgG and F(ab')â each in 4 patients (pts). The antibody was labeled using iodogen and tested for specific binding to hbc membrane extracts prior to injection. Pts received 0.6-1.1 mCi of I-131 and 50-100 ..mu..g of protein. Blood clearance of I-131 activity was biphasic with half times of 2 and 15.4 hrs for IgG; 1 and 30 hrs for F(ab')â. Dehalogenation was noted: by 72 hrs post-injection, 22% (IgG) and 21% (F(ab')â) of the injected dose of I-131 was found in the urine. In 2 pts receiving I-131 IgG, stomach uptake was 7-10% at 24 hrs. Protein associated activity in the blood was >90% for the first 8 hrs and gradually decreased to 79% (IgG) and 58% (F(ab')â) at 48 hrs. High liver uptake, reported with other antibody systems, was not observed;

Society of Nuclear Medicine Annual Meeting Abstracts, May 1, 2008

Targeted Diagnosis and Therapy, Feb 1, 1992

The Journal of Nuclear Medicine, Jul 1, 1990

tigators have presented pharmacokinetic studies of var ious MAbs (3,19-24). These reports have sh... more tigators have presented pharmacokinetic studies of var ious MAbs (3,19-24). These reports have shown that the circulating half-lives for individual antibodies vary and are dependent upon tissue reactivities and the dose ofMAb administered. The plasma half-life ofone MAb (17-lA), administered intravenously to colorectal car

TM-601, a 36-amino-acid peptide, selectively binds to glioma cells but not normal brain parenchym... more TM-601, a 36-amino-acid peptide, selectively binds to glioma cells but not normal brain parenchyma. A phase I/II clinical trial of intracavitary 131 I-TM-601 in adult patients with recurrent highgrade glioma was performed to determine the biodistribution and toxicity of this potential therapy. We evaluated imaging and biodistribution data from this trial to assess whether 131 I-TM-601 might be useful in determining tumor extent. Methods: Adult patients with recurrent high-grade gliomas underwent tumor resection, implantation of an intracavitary reservoir, and a single-dose injection of 370 MBq (10 mCi) 131 I-TM-601 (0.25-1.0 mg of 131 I-TM-601) 2-4 wks after surgery. Total-body planar scans and whole-brain SPECT scans were obtained on days 0, 1, 2, 3, and 6 -8 after injection. Postresection MR images were coregistered to the SPECT scans using image analysis software. Analysis of the rate of radioactive decay and biologic elimination from the body and at the cavity site was performed. T1-weighted with gadolinium contrast (T1-Wc), T2-weighted (T2), and SPECT volumes were estimated by stereological Cavalieri sections and compared for overlap. Results: Nonbound 131 I-TM-601 was eliminated by 48 h after injection with the remaining radiolabeled peptide bound to tumor for at least 6 -8 d. Biologic decay rates from 24 to 168 h after injection were only slightly shorter than the physical decay of 131 I (6.3 vs. 8.0 d). A comparison of tumor volume estimates using all 3 imaging parameters indicated that 131 I-TM-601-determined tumor volumes more closely paralleled T2 volumes than T1-Wc volumes. Overlap between coregistered MRI and SPECT scans corroborated the presence of radiolabeled peptide in the vicinity of infiltrating tumor up to 168 h after injection. Conclusion: 131 I-TM-601 provides a reliable estimate for primary tumor extent. Further modification of this radiopeptide with other better imaging isotopes may provide an important tool for determining tumor extent and differentiating regions of viable tumor from necrosis.

Antibody fragments with optimized pharmacokinetic profiles hold potential for detection and thera... more Antibody fragments with optimized pharmacokinetic profiles hold potential for detection and therapy of tumor malignan- cies. We studied the behavior of three anti-carcinoembryonic antigen (CEA)single-chain Fv-Fc (scFv-Fc)variants (I253A, H310A, and H310A/H435Q; Kabat numbering system)that exhibited differential serum persistence. Biodistribution studies done on CEA-positive tumor xenografted mice revealed that the 111In-labeled I253A fragment with the slowest clearance kinetics (T1/2B, 27.7 h)achieved

The quarterly journal of nuclear medicine : official publication of the Italian Association of Nuclear Medicine (AIMN) [and] the International Association of Radiopharmacology (IAR), 1999

Monoclonal antibodies (MAbs) may be considered 'magic bullets' due to their ability to re... more Monoclonal antibodies (MAbs) may be considered 'magic bullets' due to their ability to recognize and eradicate malignant cells. MAbs, however, have practical limitations for their rapid application in the clinics. The structure of antibody molecules can be engineered to modify functional domains such as antigen-binding sites and/or effector functions. Advances in genetic engineering have provided rapid progress in the development of new immunoglobulin constructs of MAbs with defined research and therapeutic application. Recombinant antibody constructs are being engineered, such as human-mouse chimeric, domain-dispositioned, domain-deleted, humanized and single-chain Fv fragments. Genetically-engineered antibodies differ in size and rate of catabolism. Pharmacokinetic studies show that the intact IgG (150 kD), enzymatically derived fragments Fab' (50 kD) and single chain Fv (28 kD) have different clearance rates. These antibody forms clear 50% from the blood pool in 2.1 d...

Cancer research, Jan 15, 1988

The B72.3 reactive antigen, TAG-72, has been purified and a series of second generation monoclona... more The B72.3 reactive antigen, TAG-72, has been purified and a series of second generation monoclonal antibodies (MAbs), designated CC (colon cancer), have been characterized by a range of in vitro immunological assays. Six CC MAbs (CC11, CC30, CC46, CC49, CC83, and CC92) were chosen for analyses of the in vivo binding to a human colon carcinoma xenograft. All 6 MAbs were previously shown to be distinct from B72.3 and each other by a series of reciprocal competition radio-immunoassays, and all were shown to have a Ka higher than that of B72.3. In this study we demonstrate that all six CC MAbs evaluated are superior to B72.3 in an in vivo tumor targeting model, using human colon carcinoma (LS-174T) xenografts in athymic mice, in terms of both the percentage of the injected dose of radiolabeled MAb delivered per g of tumor and tumor:normal tissue ratios. Differences in the in vivo binding patterns and pharmacokinetics among the CC MAbs are also evaluated. Thus, in light of the fact that ...

Cancer research, 1988