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Biomedical subjects

N K Cheung

Publications and source records attributed to N K Cheung.

At least 109 records · Page 6Linked to original sources
PubMed1993

Treatment of spinal epidural neuroblastoma xenografts in rats using anti-GD2 monoclonal antibody 3F8.

Epidural neuroblastoma xenografts in nude rats causing paraparesis were treated with intravenous injection of an anti-GD2 monoclonal antibody 3F8. Metastatic or primary epidural tumors in humans cause rapid neurologic compromise. Treatment is often unsatisfactory. An animal model was established to study antibody targeted therapy of epidural tumor. Human neuroblastoma was xenotransplanted into the thoracic epidural space of nude rats. When paraparesis developed, animals were treated intravenously with an anti-GD2 monoclonal antibody, 3F8, either alone or radiolabeled with 131Iodine. Improvement in neurologic function occurred in 2 of 20 (10%) animals receiving no treatment or control antibody, 14 of 17 (82%) animals receiving 3F8 alone and all 9 animals receiving 131I-3F8 (p < 0.0001 for 3F8 or 131I-3F8 vs. control). Six animals treated with 3F8 alone recovered normal neurologic function and remained well until sacrifice 10 days later. Four animals treated with 3F8 alone had no tumor evident on pathologic examination. The percent injected dose of 131I-3F8/g tumor in 5 samples ranged from 0.73% to 3.8%. These observations demonstrate that neoplastic epidural compression of the spinal cord in the rat can be treated successfully with intravenous unmodified monoclonal antibody and that signs of neurologic dysfunction can be reversed. The potential of this approach in treating patients with epidural tumors and other neoplasms, especially those that are not sensitive to chemotherapy or radiotherapy, deserves to be explored.

Animals↗
PubMed1993

Preferential amplification of the paternal allele of the N-myc gene in human neuroblastomas.

Genomic imprinting plays a role in influencing the parental origin of genes involved in cancer-specific rearrangements. We have analysed 22 neuroblastomas with N-myc amplification to determine the parental origin of the amplified N-myc allele and the allele that is deleted from chromosome 1p. We analysed DNA from neuroblastoma patients and their parents, using four polymorphisms for 1p and three for the N-myc amplicon. We determined that the paternal allele of N-myc was preferentially amplified (12 out of 13 cases; P = 0.002). However, the paternal allele was lost from 1p in six out of ten cases, consistent with a random distribution (P > 0.2). These results suggest that parental imprinting influences which N-myc allele is amplified in neuroblastomas, but it does not appear to affect the 1p allele that is deleted in the cases that we have examined.

Adrenal Gland Neoplasms↗
PubMed1992

Expression of disialogangliosides GD2 and GD3 on human soft tissue sarcomas.

METHODS: Fifty-six freshly frozen human sarcomas were studied for expression of disialogangliosides by avidin-biotin immunohistochemical staining with purified monoclonal antibodies (MoAb) 3F8 (antidisialoganglioside GD2) and R24 (antidisialoganglioside GD3). RESULTS: Ninety-three percent of the tumors tested by the immunohistochemical staining expressed GD2 and 88% expressed GD3. The intensity of expression varied among sarcomas of different histologic types. Liposarcoma, fibrosarcoma, malignant fibrous histiocytoma, leiomyosarcoma, and spindle cell sarcoma reacted strongly with 3F8 and R24. Embryonal rhabdomyosarcoma and synovial sarcoma demonstrated substantially weaker staining by either MoAb. Weakly reactive or nonreactive tumors were, in general, high-grade or metastatic sarcomas. Ganglioside extraction and thin-layer chromatography/immunothin-layer chromatography of two liposarcomas confirmed the identities of these gangliosides. CONCLUSIONS: GD2 and GD3 may indicate sites for MoAb-targeted imaging and therapy for sarcomas. The association of a diminished stainability by 3F8 and R24 with aggressive sarcomas may indicate prognostic significance.

Gangliosides↗
PubMed1992

Absolute requirement of CD11/CD18 adhesion molecules, FcRII and the phosphatidylinositol-linked FcRIII for monoclonal antibody-mediated neutrophil antihuman tumor cytotoxicity.

We have previously shown that 3F8, a murine IgG3, monoclonal antibody (MoAb) specific for the ganglioside GD2, mediates tumor cell kill in vitro and in vivo. We now describe receptor requirements of polymorphonuclear leukocytes (PMN) in 3F8-mediated cytotoxicity (ADCC) of human GD2 (+) melanoma and neuroblastoma cell lines. PMN from a child with leukocyte adhesion deficiency (LAD) were devoid of CD11/CD18 adhesion molecules and mounted no detectable ADCC. MoAb to CD11b, CD11c, and CD18 each efficiently blocked ADCC by normal PMN. In contrast, a panel of different MoAbs to CD11a had no significant inhibitory effect on ADCC, a finding consistent with the low-to-absent expression of the CD11a ligand, intercellular adhesion molecule-1, on the target cells. Granulocyte-macrophage colony-stimulating factor (GM-CSF) significantly increased the expression of CD11b, CD11c, and CD18 on normal PMN, decreased the expression of Fc receptors (FcR), and enhanced ADCC by normal but not by LAD PMN. MoAbs to FcRII and FcRIII each efficiently blocked ADCC; anti-FcRI MoAb had no effect. Flow cytometry using anti-FcRII MoAb versus anti-FcRIII MoAb did not show cross competition, suggesting that inhibition of ADCC was not a steric effect resulting from FcRII proximity to FcRIII. PMN deficient in FcRIII (obtained from patients with paroxysmal nocturnal hemoglobinuria) and PMN depleted of FcRIII by treatment with elastase or phosphatidylinositol (PI)-specific phospholipase C produced low ADCC, supporting a role for the PI-liked FcRIII. Thus, optimal ADCC using human PMN, human solid tumor cells, and a clinically active MoAb (conditions that contrast with the heterologous antibodies and nonhuman or nonneoplastic targets used in most models of PMN ADCC) required CD11b, CD11c, FcRII, and the PI-linked FcRIII. Furthermore, in this clinically relevant system, GM-CSF enhancement of antitumor PMN ADCC correlated with increased expression of CD11/CD18 molecules.

Antibodies, Monoclonal↗
PubMed1992

A novel O-acetylated ganglioside detected by anti-GD2 monoclonal antibodies.

Murine monoclonal antibody (MAb) 3F8 was previously shown to react with disialoganglioside GD2, but not with GD3, GT1b, GD1b, GD1a, GM1, GM3 and GM4. However, when the base-treatment step was ommitted from the standard neuroblastoma ganglioside extraction procedure, immuno-thin-layer-chromatography (ITLC) using 3F8 and other anti-GD2 MAbs revealed a new ganglioside band, abbreviated as NG (Rf 0.342) besides GD2 (R 0.183). It migrated below GD3 (Rf 0.358) on high-performance (HP) TLC plate and its binding to 3F8 on ITLC could be inhibited by rat anti-3F8 idiotypic antibody Idio-2, while the binding of GD2 to MAb 3F8 was not affected. Immunochemical analysis showed that this new neuroblastoma ganglioside contained alkali-sensitive O-acetylated sialic-acid residues recognized by MAb DI.I. After base treatment, its subsequent identity on ITLC was confirmed to be GD2. Lactonization of GD2 yielded 2 major bands, with Rf values (0.401, 0.583) distinct from that of the new ganglioside band. In addition, MAb DI.I did not bind to any of these GD2 lactones. Of 15 anti-GD2 MAbs studied, 13 reacted strongly with the novel ganglioside NG. By ITLC, this NG was found in ganglioside extracts of fresh surgical tumor specimens (4/4 neuroblastomas, I/I schwannoma and I/I anaplastic astrocytoma), and nude mice/rat xenografts (2/2 neuroblastomas, 2/2 osteogenic sarcomas). These data provided the first evidence that O-acetylated GD2 is a naturally occurring ganglioside derivative in human tumors and that it could cross-react with most anti-GD2 antibodies.

Acetylation↗
PubMed1991

Clinically effective monoclonal antibody 3F8 mediates nonoxidative lysis of human neuroectodermal tumor cells by polymorphonuclear leukocytes.

Most studies of antibody-dependent cellular cytotoxicity (ADCC) by polymorphonuclear leukocytes (PMN) have supported oxidative lytic processes. This may be because the studies used nonhuman or nonneoplastic cells that were highly sensitive to reactive oxygen species or were small enough to be phagocytosed by PMN. We therefore investigated whether oxygen radicals participate in PMN cytotoxicity toward human neuroectodermal solid tumor cells sensitized by 3F8, which is an anti-ganglioside GD2 murine IgG3 monoclonal antibody with documented anticancer activity in humans. A 4-h 51Cr release assay was used to assess tumor cell lysis by hydrogen peroxide, superoxide, and hypochlorite. Nine of 11 GD2(+) human melanoma and neuroblastoma cell lines had equal or greater resistance to these oxidants as compared to a GD2(-) human carcinoma line (SKBr1-III) found by others (and confirmed by us) to be significantly more resistant to oxidative lysis than a murine cell line (P388D1) representative of those commonly used in cytotoxicity assays. To facilitate detection of oxidant-mediated lysis, subsequent studies of 3F8-mediated ADCC used GD2(+) targets that were relatively sensitive and others that were relatively resistant to oxygen radicals. Normal PMN and PMN obtained from children with chronic granulomatous disease, which do not generate reactive oxygen species, were equally effective in ADCC. Granulocyte-macrophage colony-stimulating factor, which primes oxidative responses of normal but not of chronic granulomatous disease PMN, enhanced ADCC by both kinds of PMN. During ADCC of 3F8-sensitized targets, with or without granulocyte-macrophage colony-stimulating factor, GD2(-) "innocent bystander" tumor cells (including P388D1) were not lysed, a finding consistent with unimportant extracellular release of cytotoxic mediators. Finally, antioxidant and antimyeloperoxidase moieties did not block ADCC. We conclude that oxidants are not key factors in 3F8-mediated lysis by PMN of human neuroectodermal tumor cells.

Antibodies, Monoclonal↗
PubMed1991

High-dose melphalan with 6-hydroxydopamine-purged autologous bone marrow transplantation for poor-risk neuroblastoma.

Long-term results are presented of 28 patients who were diagnosed with neuroblastoma at more than 12 months of age and who received melphalan 180 mg/m2 (n = 6) or 240 mg/m2 (n = 22) to consolidate remissions of Stage IV disease or to control refractory disease. Twenty-four patients also received dianhydrogalactitol 180 to 240 mg/m2, and 11 received total body irradiation 450 to 600 cGy. Autologous bone marrow transplantation (ABMT) was performed with marrow that was unpurged (n = 2) or purged ex vivo (n = 26) with 6-hydroxydopamine (6-OHDA) 20 micrograms/ml plus ascorbate 200 micrograms/ml. The median time to an absolute neutrophil count of 500/microliters was 21 days and to self-sustaining platelet counts more than 20,000/microliters, 28 days. One patient required infusion of unpurged reserve marrow. Two groups of patients underwent ABMT: (1) 17 patients (Group I) who were in first remission a median of 7 months after diagnosis; and (2) 11 patients (Group II) who had refractory disease or were in second remission. For Group I, event-free survival was 29% at 12 months and 6% at 24 months post-ABMT. All Group II patients died of disease or ABMT-related toxicity. Overall, of the 28 patients, one is a long-term relapse-free survivor; five died of ABMT-related toxicity; ten patients with tumors present at ABMT had progressive disease within 6 months of ABMT; and 12 patients with no measurable disease at ABMT relapsed 4 to 32 months (median, 12) post-ABMT. Among the latter, six relapses involved the primary site, and six were restricted to distant sites. These results--in accord with the long-term outcome in other series--suggest that for neuroblastoma high-dose melphalan cannot be relied on to ablate residual disease or to salvage patients with refractory tumors. In addition, the pattern of relapse in several patients could be explained by infusion of incompletely purged autografts; this would support recent laboratory evidence that 6-OHDA/ascorbate is a suboptimal purging method.

Adolescent↗
PubMed1991

Role of low-affinity Fc receptors in antibody-dependent tumor cell phagocytosis by human monocyte-derived macrophages.

Human monocyte-derived macrophages (MDM) mediate efficient antibody-dependent cellular cytotoxicity (ADCC) against a variety of human tumor cell types in the presence of an anti-tumor monoclonal antibody. We have recently shown that the mechanism of this ADCC in our in vitro system involves phagocytosis of intact tumor cells. Some forms of macrophage ADCC have been reported to be inhibited by serum immunoglobulin, which competes with monoclonal antibodies for binding to the high-affinity Fc receptor (FcRI). In this study we investigated the role of the three macrophage FcR-gamma in antibody-dependent tumor cell phagocytosis. Hybridoma cells bearing surface antibody directed against either of the two low-affinity Fc receptors (FcRII or FcRIII) were efficiently phagocytosed by MDM, compared to hybridomas bearing irrelevant antibody. Soluble anti-receptor antibodies against FcRII and FcRIII were able to inhibit ADCC but only when both antibodies were simultaneously present. These data suggest that either low-affinity Fc receptor is capable of functioning independently to mediate phagocytosis of tumor cells. Consistent with a mechanism involving the low-affinity receptors rather than FcRI, antibody-dependent phagocytosis occurred in the presence of human serum, purified human IgG, and irrelevant murine antibody. Greater than 75% of the MDM in our culture system were able to ingest tumor cells when a suitable target was available. Optimal phagocytosis occurred at monoclonal antibody concentrations of 10-100 ng/ml. Like other forms of macrophage phagocytosis, ingestion of tumor cells required the presence of divalent cations (either Ca2+ or Mg2+) and an intact actin cytoskeleton (as indicated by sensitivity to cytochalasin D). Because FcRI is normally occupied in vivo by serum immunoglobulin, the participation of low-affinity FcR in tumor cell phagocytosis is potentially important in establishing the in vivo applicability of this efficient form of cytotoxicity.

Animals↗
PubMed1991

Technical challenges associated with the radiolabeling of monoclonal antibodies utilizing short-lived, positron emitting radionuclides.

Many factors, both physical and chemical, affect the radiolabeling of a chemical compound. These factors add a new dimension of complexity when the labeling of monoclonal antibodies is attempted with short-lived, positron emitting radionuclides. A lack of appreciation for the unique chemical separations associated with the radionuclide incorporated into the synthetic precursor can often lead to unexpected or non-reproducible results.

Antibodies, Monoclonal↗
PubMed1991

Immunotherapy. Neuroblastoma as a model.

Combinations of aggressive therapy and radiotherapy directed at the primary tumor site as well as dose intensive chemotherapy against metastases can effectively induce complete remissions in patients with stage IV neuroblastomas. By virtue of its tumor specificity, the use of immunotherapy at the time when microscopic residual disease is present holds great promise in eradicating the tumors permanently. Monoclonal antibodies can accumulate selectively and at high concentrations in neuroblastomas. They have the potential of initiating complement activation and inflammation at the tumor site. Hematopoietic factors and cytokines can reinforce the body with tumoricidal leukocytes. Ex vivo activation of autologous white cells as well as arming by genetic manipulation can also produce tumor-seeking vehicles that may be therapeutically useful. As the knowledge of tumor and host immunobiology accumulates, the optimal combination of these approaches will become apparent.

Antibodies, Monoclonal↗
PubMed1991

Myeloablative combination chemotherapy without total body irradiation for neuroblastoma.

Myeloablative treatment intensification in 25 patients diagnosed when older than 12 months of age with stage IV neuroblastoma included sequential delivery of cisplatin 120 mg/m2 x 1, hyperfractionated radiation (2,100 cGy) to the primary site and adjacent lymph nodes, carmustine (BCNU) 200 mg/m2 x 1, melphalan 60 mg/m2/d x 3 (n = 13) or thiotepa 300 mg/m2/d x 3. (n = 12), and etoposide (VP 16) 300 mg/m2/d x 3. Seventy-two hours after the last dose of VP 16, histologically tumor-free and 4-hydroperoxycyclophosphamide (4-HC; 100 mumol/L)-purged autologous bone marrow (ABMT) was infused. Acute toxicities included grade 3 to 4 oral mucositis, grade 1 to 2 diarrhea, and fevers. No patient required infusion of unpurged reserve autografts. At ABMT, 16 patients (group I) were progression-free 6.5 months to 14 months (median, 9 months) from diagnosis: seven remain progression-free 20 months to 46 months (median, 39 months) off therapy, six relapsed 4 months to 17 months post-ABMT, and three died of toxicity (candidiasis, metabolic derangement, and venoocclusive disease [VOD]). The event-free survival of group I patients is 44% at 24 months post-ABMT. Nine patients (group II) were in second remission at ABMT, including three who had relapsed after other transplant procedures: two are progression-free 24 months and 41 months off therapy, four relapsed 3 months to 12 months post-ABMT, and three died of toxicity (aspergillosis, hemorrhagic cystitis, VOD). Only one of 10 relapses involved a primary site, suggesting a beneficial effect of local radiation. In terms of survival or toxicity, an advantage for melphalan or thiotepa was not evident. Regimens such as this may prolong the survival of selected patients with poor-risk neuroblastoma, but concerns over late relapses and toxicity mandate continuing efforts to devise alternative, less risky, and more clearly beneficial approaches for definitive ablation of neuroblastoma.

Adrenal Gland Neoplasms↗