Pharmacokinetics and tumor localization of 131I-labeled anti-tenascin monoclonal antibody 81C6 in patients with gliomas and other intracranial malignancies.

We previously have reported that radioiodinated anti-tenascin monoclonal antibody 81C6 exhibits therapeutic potential against both s.c. and intracranial human glioma xenografts in athymic mice and rats.

Increased melphalan activity in intracranial human medulloblastoma and glioma xenografts following buthionine sulfoximine-mediated glutathione depletion.

In previous studies we demonstrated that administration of buthionine sulfoximine (BSO) to athymic BALB/c mice bearing intracranial human glioma xenografts resulted in highly selective depletion of glutathione in neoplastic tissue with minimal effects on contralateral normal brain tissue. In the present study we treated athymic BALB/c mice bearing intracranial human glioma (D-54 MG) or medulloblastoma (TE-671) xenografts with melphalan alone or BSO followed by melphalan. Administration of BSO depleted intracellular glutathione to 7.

O6-alkylguanine-DNA alkyltransferase and sensitivity to procarbazine in human brain-tumor xenografts.

The level of O6-alkylguanine-deoxyribonucleic acid (DNA) alkyltransferase (AT) was determined in 15 human brain-tumor xenografts in athymic mice. This enzyme is a primary intracellular repair mechanism for lesions produced at the O6 position of guanine by a wide range of alkylating agents, including nitrosoureas and procarbazine. Its activity ranged from undetectable in five tumor lines to 2338 fmol/mg protein in N-1941, a human glioblastoma xenograft.

Ganglioside mapping of a human medulloblastoma xenograft.

The ganglioside patterns of medulloblastomas have never been established; in this study we report the ganglioside profile of the human medulloblastoma cell line TE-671 grown as a xenograft in nude mice. Gangliosides were isolated and structurally analyzed by fast atom bombardment mass spectometry following permethylation. Identification of individual gangliosides was also performed by immunostaining of high-performance thin-layer chromatography-separated bands.

Expression of O6-alkylguanine-DNA alkyltransferase in Mer+ and Mer- human cell extracts probed with specific monoclonal antibodies.

The response of human cells to the mutagenic, carcinogenic, and lethal effects of alkylating agents that produce O6-alkylguanine adducts in DNA is largely determined by the cellular content of O6-alkylguanine-DNA alkyltransferase. Because a subgroup of human tumor cell lines (termed Mer-) that are hypersensitive to such agents appears to lack the transferase activity, we questioned whether this DNA-repair protein is produced in a non-functional mutant form or is simply not expressed in such cells. Ten human cell lines were examined by immunoblot analysis of crude extracts with monoclonal antibodies specific for the human alkyltransferase.

GD3 expression by cultured human tumor cells of neuroectodermal origin.

Seven monoclonal antibodies (mAbs) reactive with ganglioside II3(NeuAc)2-LacCer (GD3) were generated; four of these mAbs (DMAb-21, DMAb-22, DMAb-23, and DMAb-24) by immunizing mice with GD3 adsorbed to Salmonella minnesota and the remaining three (DMAb-7, DMAb-8, and DMAb-17) with melanoma line SK-MEL 28, which contains 1.4 nmol sialic acid of GD3 per mg protein. The specificities of the mAbs were defined by high-performance thin-layer chromatography (HPTLC) immunostain and solid-phase radioimmunoassay (SP-RIA) with a panel of purified gangliosides.

Synthesis of radioiodinated N-succinimidyl iodobenzoate: optimization for use in antibody labelling.

N-succinimidyl-3-(tri-n-butylstannyl)benzoate (m-BuATE), N-succinimidyl-3-(tri-methylstannyl)benzoate (m-MeATE) and N-succinimidyl-4-(tri-n-butylstannyl)benzoate (p-BuATE) were synthesized and radioiodinated using either N-chlorosuccinimide (NCS) or t-butylhydroperoxide (TBHP) as the oxidant. Radiohalogenation of m-MeATE proceeded more rapidly than m-BuATE. NCS was the more efficient oxidant at reaction times less than 15 min; use of both TBHP and NCS resulted in nearly quantitative yields after 15 min when m-MeATE was used.

Phenotypic analysis of four human medulloblastoma cell lines and transplantable xenografts.

An extensive panel of monoclonal antibodies (MAb) and monospecific antisera reactive against neuroectodermal-, neuronal-, glial-, and lymphoid-associated antigens, extracellular matrix, HLA, and cell-surface receptors was used to characterize the phenotype of four continuous, karyotypically distinct medulloblastoma cell lines and transplantable xenografts. All four cell lines demonstrated significant reactivity with anti-neuroectodermal-associated MAb. No apparent pattern of reactivity with anti-lymphoid MAb was seen; notably, there was a uniform absence of detectable Thy-1.

Buthionine sulfoximine-mediated depletion of glutathione in intracranial human glioma-derived xenografts.

D-54 MG, a human glioma-derived continuous cell line growing as subcutaneous or intracranial xenografts in athymic mice, was found to be sensitive to the effects of D,L-buthionine-(SR)-sulfoximine, a selective inhibitor of gamma-glutamylcysteine synthetase. Intraperitoneal administration of one dose of buthionine sulfoximine (BSO, 5 mmol/kg) resulted in depletion of total intracellular glutathione to 57 and 47% of control 12 hr, and 73 and 23% of control 24 hr, after BSO in subcutaneous and intracranial xenografts respectively. Concurrent measurement of total glutathione in the contralateral (non-tumor-containing) cerebral hemisphere in mice bearing intracranial D-54 xenografts demonstrated insignificant depletion of glutathione.

Comparative localization of murine monoclonal antibody Me1-14 F(ab')2 fragment and whole IgG2a in human glioma xenografts.

Monoclonal antibodies (MAbs) targeted to glioma-associated antigens may allow the selective delivery of imaging and therapeutic agents to brain tumors; the use of MAb fragments may be a strategy to further improve tumor uptake of such agents relative to normal tissues. In this study, we have examined the in vivo localization of radioiodinated MAb Me1-14, a murine immunoglobulin G2a (IgG2a) reactive with gliomas, and its F(ab')2 fragment in s.c.

Melphalan transport, glutathione levels, and glutathione-S-transferase activity in human medulloblastoma.

Melphalan transport, glutathione levels, and glutathione-S-transferase activity were measured in two continuous human medulloblastoma cell lines and transplantable xenografts in athymic nude mice, TE-671 and Daoy. In vitro mean glutathione levels were 10.06 nmol/10(6) cells in TE-671 and 2.

Experimental chemotherapy of human medulloblastoma cell lines and transplantable xenografts with bifunctional alkylating agents.

A series of bifunctional alkylators were tested against the genotypically and phenotypically heterogeneous continuous human medulloblastoma cell lines, TE-671, Daoy, and D283 Med in vitro and against TE-671 and Daoy growing as s.c. and intracranial xenografts in athymic mice.

Enhanced melphalan cytotoxicity following buthionine sulfoximine-mediated glutathione depletion in a human medulloblastoma xenograft in athymic mice.

The effect and therapeutic consequences of buthionine-(SR)-sulfoximine (BSO)-mediated depletion of glutathione in the human medulloblastoma-derived cell line, TE-671, growing as s.c. xenografts in athymic nude mice were examined.

Treatment of intracranial human glioma xenografts with 131I-labeled anti-tenascin monoclonal antibody 81C6.

Lack of tumor specificity renders current modalities for treating malignant glioma ineffective. The administration of 131I-labeled monoclonal antibody (Mab) 81C6, which reacts with the glioma-associated extracellular matrix antigen, tenascin, to nude mice carrying s.c.

Gene amplification in malignant human gliomas: clinical and histopathologic aspects.

Gene amplification occurs in 45-50% of malignant human gliomas (MHG). In the present study, 64 genetically characterized gliomas were evaluated to determine if tumors with amplification of the epidermal growth factor receptor (EGFR), N-myc, c-myc, or gli genes had distinctive histopathologic features. There was no significant difference in age (p = 0.

Amplification and expression of the epidermal growth factor receptor gene in human glioma xenografts.

Xenografts from eight malignant human gliomas were established in athymic mice and were used to study amplification and expression of the epidermal growth factor receptor (EGFR) gene. Tissue identity between biopsy and xenografts was confirmed by karyotypic profiles, which showed that each glioma xenograft retained structural abnormalities, including double minute chromosomes, present in the parent glioma. EGFR gene amplification was found in six of the eight glioma biopsies and their corresponding xenografts.

Therapeutic efficacy of antiglioma mesenchymal extracellular matrix 131I-radiolabeled murine monoclonal antibody in a human glioma xenograft model.

The development of Mabs, particularly those reactive with primary brain tumors but not with normal brain, provides a potential means of delivering therapeutic agents selectively to human malignant gliomas. Mab 81C6, an IgG2b immunoglobulin, which defines an epitope of the glioma-associated extracellular matrix protein tenascin, has been shown to bind to human glioma cell lines, glioma xenografts in nude mice, and primary human gliomas, but not to normal adult or fetal brain. To test the therapeutic potential of this Mab for targeted delivery of isotopes, nude mice bearing progressively growing s.

Specific chromosomal abnormalities in malignant human gliomas.

Karyotypic analysis of 54 malignant human gliomas (5 anaplastic astrocytomas, 43 glioblastoma multiformes, 3 gliosarcomas, 2 giant cell glioblastomas, 1 anaplastic mixed glioma) has demonstrated that 12 tumors contained normal stemlines or only lacked one sex chromosome. The 42 tumors with abnormal karyotypes included 38 tumors which could be completely analyzed. Six of these 38 cases had near-triploid or near-tetraploid stemlines and 32 had near-diploid stemlines.

Structural chromosomal abnormalities in human medulloblastoma.

Seven human medulloblastomas (four primary cerebellar, three recurrent or metastatic) were karyotyped in direct preparation and/or short-term or early culture. One tumor had a 46,XX stem line. Four of the six remaining tumors contained one or more i(17q), and three of these six tumors had deletions of extra copies of chromosome #1, resulting in trisomy of 1p, 1q, or both.

The localisation of radiolabelled murine monoclonal antibody 81C6 and its Fab fragment in human glioma xenografts in athymic mice.

The localisation of the radioiodinated Fab fragment of monoclonal antibody (Mab) 81C6, reactive with a glioma-associated extracellular matrix antigen, was studied in athymic mice bearing subcutaneous and intracranial xenografts of D-54 MG glioma cells. In vitro 81C6 Fab showed a marked loss of immunoreactivity and affinity for antigen compared to intact Mab 81C6. In vivo, the plasma half-life of 81C6 Fab was 7.

Growth effects of epidermal growth factor (EGF) and a monoclonal antibody against the EGF receptor on four glioma cell lines.

Epidermal growth factor (EGF) has been shown to stimulate DNA synthesis and cell division in normal glia. At least half of malignant human gliomas (MHG) express high levels of the EGF receptor (EGFR), which are above those detected in normal brain. The demonstration that antibodies against the EGFR inhibit the growth of squamous cell carcinoma line A-431, with large numbers of EGFR, in vitro and in vivo raises the possibility that these agents could be used therapeutically against malignant human gliomas either alone or conjugated to other agents.

Intravenous adenosine selectively increases blood flow to xenotransplanted intracerebral gliomas.

Adenosine was infused intravenously at 10 mumol/(kg.min) into athymic ("nude") rats with intracerebral D-54MG xenotransplanted brain tumors, in an attempt to increase tumor blood flow. Cerebral blood flow (F) was measured with 14C-iodoantipyrine and quantitative autoradiography.

Distribution of type VI collagen in human gliomas: comparison with fibronectin and glioma-mesenchymal matrix glycoprotein.

The distribution of type VI collagen was examined immunohistochemically in normal tissues and in 24 human gliomas and six medulloblastomas. Its localization in the neoplasms was compared with that of fibronectin and glioma-mesenchymal extracellular matrix (GMEM) glycoprotein. In normal non-neural tissues type VI collagen was demonstrated in the interstitial connective tissue and in some basement membranes.

Relationship between gene amplification and chromosomal deviations in malignant human gliomas.

Biopsies of 33 malignant human gliomas were karyotyped and evaluated for amplification (more than eight gene copies per cell) of the epidermal growth factor receptor (EGFR), N-myc, c-myc, and gli genes by Southern blot analysis. Fifteen of 33 tumors showed amplification of EGFR, none had amplified c-myc, one tumor had amplified N-myc, and one had amplification of gli. Thirteen of the 16 (81%) evaluable tumors with gene amplification contained double minutes (DM), and only four of 16 (25%) tumors without demonstrable amplification contained these structures.