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Biomedical subjects

N K Cheung

Publications and source records attributed to N K Cheung.

At least 145 records · Page 8Linked to original sources
PubMed1989

In vitro chemopurification of neuroblastoma cells: comparison of 6-hydroxydopamine and ascorbic acid with 4-hydroperoxycyclophosphamide.

To develop an effective neuroblastoma (NB) purging condition, we have compared in vitro cytotoxicity of 6-hydroxydopamine (6-OHDA) and ascorbic acid, with 4-hydroperoxycyclophosphamide (4-HC) on three NB cell lines (SK-N-BE2, SMS-SAN, and LA-N-1) and also upon human hematopoietic stem cells. Our study included mixing NB cells with 20-fold excess of irradiated bone marrow buffy coat cells to simulate the borderline remission marrow. When NB cells were treated without marrow cells, all three NB cell lines were very sensitive to 6-OHDA; complete inhibition of SK-N-BE2 and SMS-SAN cells was achieved at 10 micrograms/ml, and greater than 4 log inhibition of LA-N-1 was observed at 100 micrograms/ml of 6-OHDA. Addition of marrow cells caused marked reduction of the 6-OHDA-induced cytotoxicity of NB cells, and under similar conditions, colony-forming units-granulocyte-macrophage (CFU-GM) growth was not inhibited significantly. In the absence of normal marrow cells, 60 minutes of treatment with 100 microM of 4-HC produced complete inhibition (greater than 4.5 log) of SK-N-BE2 and SMS-SAN cells, greater than 4 log inhibition of LA-N-1 cells, and 97% of CFU-GM. Addition of marrow cells reduced the cytotoxicity of 4-HC, and 100 microM of 4-HC produced 99.8% inhibition of LA-N-1 colony growth. Shortening incubation duration to 30 minutes resulted in further reduction of 4-HC cytotoxicity; 100 microM of 4-HC caused 98.3%, 45%, and 33% inhibition of LA-N-1 cells, marrow CFU-GM, and burst-forming units-erythrocytes (BFU-E), respectively. At 200 microM, complete inhibition (greater than 4 log) of LA-N-1 colony growth was noted, and 9.9% of CFU-GM and 9.3% of BFU-E growth was observed. These data favor the use of 4-HC for purging marrow of NB, cells in the clinical autologous marrow transplantation.

Antibodies, Monoclonal↗
PubMed1989

Biodistribution and dosimetry of 3F8 neuroblastoma monoclonal antibody.

A method has been developed for quantitating radiolabeled antibody concentrations from images obtained with standard gamma cameras. The method is based on orthogonal projections and accounts both for the effective attenuation of gamma rays and the finite depth dependent resolution of a gamma camera. The method was verified in experimental phantoms and subsequently used in patient studies to quantitate radiolabeled antibody concentrations in neuroblastoma tumors. The in vivo measurements of tumor radioactivity levels were confirmed at biopsy in one patient.

Antibodies, Monoclonal↗
PubMed1988

Decay-accelerating factor protects human tumor cells from complement-mediated cytotoxicity in vitro.

The disialoganglioside GD2 is expressed on a wide spectrum of human tumor types, including neuroblastomas and melanomas. Upon binding of 3F8, a murine monoclonal antibody (MAb) specific for GD2, neuroblastomas and some melanomas are sensitive to killing by human complement, whereas some melanomas are not. To investigate the mechanism underlying these differences in complement mediated cytotoxicity, complement-insensitive melanoma cell lines were compared with respect to expression of the decay-accelerating factor (DAF), a membrane regulatory protein that protects blood cells from autologous complement attack. While DAF was undetectable among neuroblastomas, it was present in complement-insensitive melanomas. When the function of DAF was blocked by anti-DAF MAb, C3 uptake and complement-mediated lysis of the insensitive melanoma lines were markedly enhanced. F(ab')2 fragments were as effective in enhancing lysis as intact anti-DAF MAb. The DAF-negative and DAF-positive melanoma cell lines were comparably resistant to passive lysis by cobra venom factor-treated serum. The data suggest that in some tumors, DAF activity accounts for their resistance to complement-mediated killing. The ability to render these cells complement-sensitive by blocking DAF function may have implications for immunotherapy.

Antibodies, Monoclonal↗
PubMed1988

Neuroblastoma.

The identification of prognostic factors has greatly facilitated the rational choice of therapies in individual patients. Intensive chemotherapy, supplemented with radiation and surgery, has increased the remission rate of patients with widespread disease. The persistence of microscopic foci of malignant cells, however, remains a difficult hurdle for long-term disease-free survival. Highly toxic myeloablative therapies have had at most a modest impact on the overall cure rate of poor-risk patients. The use of novel biological therapies has provided new information on the mechanisms and potentials of immune-mediated tumor cytotoxicity. Timely clinical trials are needed to test their role in adjuvant treatment of occult microscopic disease.

Antineoplastic Agents↗
PubMed1988

High-dose cytosine arabinoside and fractionated total-body irradiation: an improved preparative regimen for bone marrow transplantation of children with acute lymphoblastic leukemia in remission.

Twenty children with acute lymphoblastic leukemia in second (18 patients) or third (two patients) complete remission after bone marrow relapse received allogeneic bone marrow transplants from histocompatible sibling donors. The preparative regimen for marrow transplantation consisted of 12 doses of 3,000 mg/m2 cytosine arabinoside twice daily for six days followed by 1,200 cGy total-body irradiation (six doses of 200 cGy twice daily for three days). The preparative regimen was well tolerated, and all patients showed marrow engraftment promptly. Twelve patients are alive in complete remission 12+ to 79+ months posttransplant; eight patients are over 48 months posttransplant. Six patients died 1 to 9 months posttransplant of nonleukemic causes: (two each of graft-v-host disease, interstitial pneumonitis, and infection). Two patients developed recurrent leukemia at 15 and 30 months posttransplant. Both have died at 19 and 36 months posttransplant. Life table analysis reveals an actuarial survival and event-free survival rate of 58% and a marrow relapse rate of 17%. These results suggest that high-dose cytosine arabinoside and fractionated total-body irradiation is a relatively nontoxic and highly effective preparative regimen for allogeneic bone marrow transplantation for acute lymphoblastic leukemia that deserves further evaluation.

Adolescent↗
PubMed1987

Interleukin-2 enhancement of monoclonal antibody-mediated cellular cytotoxicity against human melanoma.

Disialoganglioside GD2 is present on human neuroblastoma and melanoma cells. 3F8 is a murine IgG3 monoclonal antibody specific for GD2, which has shown antitumor effects in patients in preliminary clinical studies. Since antibody mediated cellular cytotoxicity (ADCC) was one of the likely mechanisms producing these observed tumor regressions, the current study was carried out to investigate the activation of ADCC by interleukin-2 (IL-2). ADCC (against human neuroblastoma and melanoma cell lines in vitro) mediated by normal human peripheral blood lymphocytes was increased 100 to 330% after preincubation with IL-2. At limiting concentrations of 3F8 antibody (10 to 100 times less than the amount required by unactivated peripheral blood lymphocytes), activated peripheral blood lymphocytes still mediated efficient ADCC. Activation of ADCC was detected earlier than lymphokine activated killer cell (LAK) activity, required less IL-2 for optimum induction (50 versus 1000 units/ml), and was of equal or greater absolute magnitude (+10 to +200%) against the cell lines tested. ADCC and LAK were independent and additive when measured against the same cell line. The precursor cells for both LAK and activated ADCC bore IgG Fc receptors, but by day 4 of culture with IL-2 much of the LAK activity resided in the Fc negative, Leu11 negative population, and did not mediate ADCC. IL-2 activated ADCC may be of value alone or in conjunction with LAK cells in the therapy of tumors which bind the antibody 3F8.

Antibodies, Monoclonal↗
PubMed1987

Localization of GD2-specific monoclonal antibody 3F8 in human osteosarcoma.

3F8 is a murine IgG3 monoclonal antibody specific for the antigen disialoganglioside GD2. Immunofluorescence staining showed strong binding of 3F8 to 15 of 17 human osteosarcomas, including primary and metastatic tumors. The targeting potentials of the native monoclonal antibody (3F8) and the F(ab')2 fragment (p-3F8) were tested in BALB/c athymic nude mice xenografted with human osteosarcomas. After radiolabeling with iodine using the chloramine T method, both 3F8 and p-3F8 retained immunoreactivities. The irrelevant IgG3 antibody TIB114 and its F(ab')2 fragment were used as negative controls. A Ewing's sarcoma xenograft, which was low in GD2 antigen, was also studied for comparison. Mice were sacrificed 1 day and 4 days after i.v. antibody injection. 3F8 and p-3F8 showed preferential accumulation in osteosarcoma over normal tissues with tumor:nontumor ratios of 2.7-58:1 and 1.4-82:1, respectively, on Day 1. These ratios improved to 10-163:1 and 6.0-75:1 on Day 4. The intact antibody 3F8 showed selective tumor uptake with a much higher percentage of injected dose per g than the fragment p-3F8 and exhibited a longer tissue half-life than p-3F8. These data indicate that anti-GD2 monoclonal antibodies may be useful for imaging and targeted therapy of human osteogenic sarcoma. The F(ab')2 fragment has the advantage of achieving favorable tumor:nontumor ratios sooner after antibody injection while the intact antibody shows better retention by tumor tissues.

Animals↗
PubMed1987

An assessment of monocyte procoagulant activity in patients with solid tumors.

Generation of thromboplastin by monocytes has been shown to play a vital role in hypercoagulable states seen in malignancy. The purpose of this study was to compare the procoagulant activity in cancer patients and controls. Recalcification times (RT) of whole blood from 19 normal volunteers, 8 patients with benign polyps, 12 patients previously treated by surgery for head and neck (H&N) or colon cancer, and 13 untreated patients with various stages of H&N or colon cancer were determined. Tests were performed with and without stimulation with Escherichia coli endotoxin. The mean RT in saline (RTS) of untreated patients with early cancer (4.58 +/- 0.83 min) and that of patients with advanced cancer (5.23 +/- 1.16 min) were lower than that of controls (6.55 +/- 0.82 min), P less than 0.01 and P less than 0.05, respectively. The RTS of patients previously treated and of those with benign polyps were no different from those of controls. Activation with endotoxin significantly lowered the recalcification times (RTE) in the early (3.90 +/- 0.58 min) and advanced cancer patients (4.23 +/- 0.66 min) compared to the RTE of controls (5.69 +/- 0.75 min, P less than 0.01 for both groups) as well as compared to those with benign tumors, P less than 0.05. The mean RTE of previously treated patients (4.72 +/- 0.58 min) was also lower than that of controls, P less than 0.05. Our results suggest that RT is significantly reduced in cancer patients compared to that of controls. Furthermore, monocyte activation with endotoxin may enable us to distinguish cancer patients from controls as well as from those with benign tumors.

Adenoma↗
PubMed1987

Differentiation of presumed sepsis from acute graft-versus-host disease by C-reactive protein and serum total IgE in bone marrow transplant recipients.

Fever after bone marrow transplantation may indicate the onset of bacterial or opportunistic infection, or acute graft-versus-host disease (GVHD). In an attempt to differentiate between infection and GVHD, we prospectively studied 41 bone marrow transplants in 38 patients (24 allogeneic, 17 autologous). Elevation of C-reactive protein (CRP) proved to be a good indicator of disseminated infections. In 40 episodes of documented (11) or presumed (29) sepsis, CRP rose above 5 mg/dl in 38 episodes (95%), and above 10 mg/dl in 32 episodes (80%). The CRP concentration paralleled the clinical course of the infectious episodes. Elevated CRP values were not observed in the 15 episodes of acute GVHD without concurrent infection. High peak values of serum total IgE, ranging from 4-fold to over 4000-fold baseline, were observed posttransplant in 18/22 allogeneic BMT recipients, temporally associated with activation of acute GVHD. IgE was elevated neither in episodes of sepsis without concurrent GVHD, nor in viral or focal bacterial infections. In general, septic infections were characterized by high CRP but low IgE levels. Acute GVHD without concurrent infection was characterized by high IgE but low CRP. We conclude that CRP and serum total IgE utilized together in serial fashion are helpful in distinguishing sepsis from acute GVHD.

Acute Disease↗
PubMed1987

Ganglioside GD2 specific monoclonal antibody 3F8: a phase I study in patients with neuroblastoma and malignant melanoma.

The murine IgG3 monoclonal antibody (MoAb) 3F8, specific for the ganglioside GD2, activates human complement, is active in antibody-dependent cell-mediated cytotoxicity (ADCC), and can target specifically to human neuroblastoma in patients with metastatic disease. In a phase I study, 3F8 was administered intravenously (IV) to 17 patients with metastatic GD2 positive neuroblastoma or malignant melanoma at doses of 5, 20, 50, and 100 mg/m2. Serum 3F8 levels achieved were proportional to the dose of 3F8 infused. However, serum antimouse antibody levels did not increase with the amount of 3F8 administered. Toxicities included pain, hypertension, urticaria, and complement depletion. All acute side effects were controllable with symptomatic therapy. No long-term side effects were detected in patients observed for more than 14 months. None of the 17 patients received any antitumor therapy postantibody treatment. Antitumor responses occurred in seven of 17 patients. These ranged from complete clinical remissions to mixed responses. The murine monoclonal antibody (MoAb) 3F8 has clinical utility for the diagnosis and therapy of neuroblastoma and melanoma.

Adolescent↗
PubMed1987

Targeting of ganglioside GD2 monoclonal antibody to neuroblastoma.

The biodistribution of 3F8, and IgG3 murine monoclonal antibody (MoAb) specific for the disialoganglioside GD2, was studied in nude mice xenografted with human neuroblastoma (NB). 3F8 conjugated to radioactive iodine and injected intravenously localized selectively to seven human NB when compared with Ewing's sarcoma and Hela cell xenograft controls. Uptake in NB was shown to be specific for MoAb 3F8 when contrasted with pooled mouse IgG or irrelevant IgG3 MoAb controls. Both small (50 mg) and large tumors greater than 2 g) showed radiolocalization. The percent injected dose uptake per gram tumor ranged from 8 to 50% and was inversely correlated with tumor size. Optimal tumor to normal tissue ratios were reached by 24-48 hr. There was no abnormal uptake in the reticuloendothelial system and the MoAb did not cross the blood-brain barrier. Based on the kinetics of the amount of radioactivity deposited in tissues, the relative radiation dose to normal organs was estimated to be 1% to 20% of the tumor dose. The MoAb 3F8 is useful for targeting radioactivity to human NB in vivo and the nude mice xenograft model may allow optimization of parameters that influence such biodistribution.

Animals↗
PubMed1986

Complete tumor ablation with iodine 131-radiolabeled disialoganglioside GD2-specific monoclonal antibody against human neuroblastoma xenografted in nude mice.

The antibody 3F8, an IgG3 murine monoclonal antibody (MoAb) against disialoganglioside GD2, could target iodine-131 (131I) to established subcutaneous human neuroblastoma (NB) xenografts in BALB/c nude mice. 131I-radiolabeled MoAb (0.125-1 mCi) was injected iv. Tumor radioactivity over time was calculated from scintigraphy, and radiation dose to individual tumors was calculated. Tumor shrinkage occurred only with 131I-labeled 3F8, but not with nonradioactive 3F8 or radiolabeled irrelevant antibody. While the tumor of the control mice enlarged by tenfold, the treated tumor showed over 95% shrinkage by 12 days. Both the rate of shrinkage and duration of tumor response were dose dependent. Calculated doses of more than 10,000 rad could be achieved. Only those tumors that received more than 4,200 rad were completely ablated without recurrence. Recurrent tumors were not antigen negative or radioresistant. These results confirmed the prediction based on imaging studies that human NB xenografts could be effectively eradicated with the use of 131I-labeled MoAb 3F8 with tolerable toxicities.

Animals↗