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M S Mitchell

Publications and source records attributed to M S Mitchell.

At least 55 records · Page 3Linked to original sources
PubMed1991

Novel gene sequences expressed by human melanoma cells identified by molecular subtraction.

Despite the variety of approaches used, only a limited number of tumor-associated antigens have been described for each histological type of tumor. In this report, we present a new strategy involving molecular subtraction to identify novel melanoma-associated gene sequences. Toward this end, 156 complementary DNA clones were isolated with a subtracted melanoma complementary DNA probe (melanoma minus lung carcinoma) after screening 2 x 10(4) independent recombinants of a melanoma expression library by in situ plaque hybridization. These clones were then polymerase chain reaction amplified, screened for duplication, and categorized into 53 discrete genes. By applying poissonian distribution to the numbers of duplicate isolates, we found most of the genes to be rare messages, present at less than 1 copy/200 molecules of mRNA in a typical somatic cell. Messages specific for a type of tissue are usually expressed in this range. The expression of the 53 genes was further studied in human tumor cell lines and normal tissues. Partial sequence data obtained for 20 complementary DNA clones revealed 8 novel human genes. The mRNA transcripts for 5 of the novel genes were identified by Northern blot analysis. Thus, molecular subtraction appears to be applicable for the identification of novel tumor-associated sequences. Some of the potential advantages and limitations of this technology are discussed, including its application to the molecular characterization of immunogenic melanoma-associated antigens.

Antigens, Neoplasm↗
PubMed1991

Lymphocytes cytotoxic to uveal and skin melanoma cells from peripheral blood of ocular melanoma patients.

To study antitumor immunity in patients with choroidal melanoma, T cells were generated from the peripheral blood of choroidal melanoma patients by mixed lymphocyte/tumor cell culture (MLTC). Because autologous tumors are generally unavailable, an allogeneic choroidal melanoma cell line, OCM-1, was used as the specific stimulus. Lymphocyte cultures from 27 patients were characterized by cell-surface phenotypes, patterns of reactivity towards cells of the melanocytic origin and T-cell-receptor gene usage. Antimelanoma reactivity was found in cell-sorter-purified CD4+ and CD8+ T cell subsets. To analyze this reactivity, sorter-purified CD4+ and CD8+ cells from a MLTC were cloned by limiting dilution in the presence of exogenous interleukin-2 and interleukin-4 as well as irradiated OCM-1. Under these conditions, CD4+ T cells did not proliferate, perhaps because of the absence of antigen-presenting cells. However, CD8+ grew vigorously and 29 cytolytic CD8+ T cell clones were isolated. On the basis of their pattern of lysis of OCM-1, a skin melanoma cell line M-7 and its autologous lymphoblastoid cell line LCL-7, the clones were categorized into three groups. Group 1, representing 52% of the clones, lysed all three target cells, and are alloreactive. However, since OCM-1 and M-7 did not share class I antigens, these clones recognized cross-reactive epitope(s) of the histocompatibility locus antigen (HLA) molecule. Group 2, constituting 28% of the clones, lysed both the ocular and skin melanoma cell lines but not LCL-7, and were apparently melanoma-specific. Unlike classical HLA-restricted cytolytic T lymphocytes, these T cells might mediate the lysis of melanoma cells via other ligands or a more degenerate type of HLA restriction. For the latter, the HLA-A2 and -A28 alleles would have to act interchangeably as the restriction element for shared melanoma-associated antigen(s). Group 3, representing only 10% of the T cell clones, was cytotoxic only to OCM-1, but not to M-7 or LCL-7. These clones may recognize antigens unique to ocular melanoma cells. Our data suggest that choroidal melanoma patients can recognize melanoma-associated antigens common to both ocular and cutaneous melanoma cells, and presumbly their autologous tumor. Thus, choroidal melanoma, like its skin counterpart, may be responsive to immunotherapeutic regimens such as active specific or adoptive cellular immunotherapy.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1991

Evaluation of human monoclonal antibody (2-139-1) in cutaneous melanocytic neoplasms in fixed tissue sections.

Despite the growing list of xenogeneic monoclonal antibodies (MAb) that recognize malignant melanoma-associated antigens (MAA) in formalin-fixed, paraffin-embedded tissue, none has been able to detect epitopes found in malignant melanomas and not in melanocytic nevi. A human MAb, 2-139-1, that showed promise in this regard was evaluated against 85 melanocytic neoplasms, including malignant melanoma and histological simulators, particularly Spitz's nevus. MAb 2-139-1 stained 18 (53%) of 34 melanomas, eight (57%) of 14 dysplastic nevi, six (38%) of 16 Spitz's nevi, and three (14%) of 21 banal nevi, which included three small congenital nevi. We observed a significant increasing trend in reactivity (% positive cells x intensity) associated with the potential for malignancy (p for linear trend = 0.002). We conclude that human MAb 2-139-1 is applicable to the study of melanocytic neoplasms in routinely processed tissue. Although the ability of this MAb to separate benign from malignant cells is not absolute, our results suggest that the expression of the 2-139-1 epitope may be an early event in melanocytic tumor progression.

Antibodies, Monoclonal↗
PubMed1991

Attempts to optimize active specific immunotherapy for melanoma.

During the past 5 years, we have been conducting clinical trials with a therapeutic melanoma vaccine (melanoma "theraccine"). Mechanical lysates of two melanoma cell lines chosen for their complementary characteristics were combined with the adjuvant DETOX and injected subcutaneously on weeks 1, 2, 3, 4 and 6 for one or two courses, and then monthly in patients with objective clinical responses. Of 109 patients, 22 (20%) have had objective clinical regression of tumor masses, with 5% complete responses. Ten patients have lived more than a year. Eight of the 10 are still alive, five of whom have lived more than 3 years. It was not necessary to achieve complete remissions to cause an increase in survival, and most of the long-surviving patients have one or more (stable) residual nodules. The pace of the disease process has clearly been slowed in those individuals. A rise in the level of cytotoxic T lymphocyte precursors in the blood (pCTL) has correlated with clinical response. Only one patient without such a rise in pCTL has had a response, and assays in that patient were considered unreliable. Both CD4+ and CD8+ CTL have been cloned from the blood of immunized patients. Both types of CTL killed a number of melanoma cell lines, but not other types of tumor or normal cells (lymphoblasts and melanocytes). CD8+ CTL have not been restricted to killing the autologous melanoma. MHC restriction by the HLA-A2 locus was identified. CD4+ CTL were not restricted only by Class II HLA antigens. Many CD4+ clones killed HLA Class II-negative melanomas, and we were able to block cytotoxicity of a particular clone with either anti-HLA Class I or anti-Class II MHC monoclonal antibodies, or both. An association of clinical response to the theraccine with certain HLA phenotypes, notably HLA-C3, -A2 (and the cross-reactive HLA-A28), B12 (and the related alleles (HLA-B44 and -B45) and perhaps DR4, particularly when combinations of those alleles were present, was suggested by our analysis of 70 patients. It is possible that this simply indicates the sharing of MHC antigens between the immunizing melanomas and the patient's melanoma. However, these MHC molecules may be important in their own right in presenting melanoma-associated antigens in CTL in vivo. Subtractive hybridization of mRNA from lung squamous carcinoma cells from cDNA of the M-1 melanoma cell line has yielded several DNA sequences unique to melanoma. Those are now being analyzed for possible immunogenicity, with cytotoxicity by CTL from immunized patients as the major criterion.(ABSTRACT TRUNCATED AT 400 WORDS)

Adjuvants, Immunologic↗
PubMed1990

Increased lysis of melanoma by in vivo-elicited human lymphokine-activated killer cells after addition of antiganglioside antibodies in vitro.

Thirty-nine melanoma patients were treated with cyclophosphamide (350 mg/m2) followed 3 days later by 5 daily doses of interleukin 2 (3.6 million units/m2 i.v.) weekly for 2 weeks. This cycle was repeated at least twice with a 1-week interval between cycles. Natural killer and lymphokine-activated killer (LAK) cell activity in peripheral blood mononuclear cells were measured before treatment and on the last day of each cycle by chromium release assays. Development of LAK activity of greater than 10 lytic units was correlated with a clinical response. There was no correlation between natural killer activity and clinical response. Antibody-dependent cell-mediated cytotoxicity of in vivo-induced LAK cells after the addition of mouse monoclonal antibodies (MAbs) in vitro was measured in 30 cases on the last day of each interleukin 2 cycle. Anti-GD3 MAbs MB3.6, 11C64, 6H4, and R24 increased LAK cell cytotoxicity against GD3-positive GD2 melanoma cells while anti-GD2 MAb 14.18 increased LAK cell cytotoxicity against GD3-negative GD2-positive melanoma cells. MAb 9.2.27 (IgG2a) directed against a chondroitin sulfate proteoglycan and its core protein with a molecular weight of 250,000 (p250) on human melanoma cells did not mediate antibody-dependent cell-mediated cytotoxicity. The effector cells in these antibody-dependent cell-mediated cytotoxicity. The effector cells in these antibody-dependent cell-mediated cytotoxicity reactions were Leu-19 positive. In preincubation experiments the MAbs showed superior binding to the melanoma target cells than to effector cells. Our results show that low dose interleukin 2 preceded by low dose cyclophosphamide effectively induces LAK cells in vivo. The cytotoxicity of these in vivo-activated LAK cells can be augmented in vitro by mouse MAbs against glycolipid antigens on the tumor.

Antibodies, Monoclonal↗
PubMed1990

Phase I trial of a 5-day course of carbetimer.

Carbetimer (carboxyimamidate) is a low molecular weight derivative of ethylene/maleic anhydride polymer. This compound has demonstrated antitumor activity against several animal models with a daily x 5 schedule appearing most effective. A phase I clinical study of the daily x 5 schedule repeated every 28 days was therefore performed. Forty-one evaluable patients received 66 evaluable cycles of Carbetimer at daily doses ranging from 100-11,000 mg/m2. Hypercalcemia was the dose limiting toxicity with both patients at the 11,000 mg/m2 daily dose level and one patient who received 6 cycles of drug at the 4200 mg/m2 dose level developing severe hypercalcemia not explained by the underlying malignancy. Mild nausea, concentration and rate dependent arm pain at the site of infusion, proteinuria, and coagulopathy were also seen. Calcium balance studies revealed hypercalciuria, suggesting increased mobilization of calcium rather than renal retention. In vitro coagulation studies revealed concentration dependent prolongation of the partial thromboplastin time and thrombin time. No complete or partial responses were seen. However mixed response or biochemical response (reduction in serum lactic dehydrogenase) were seen in 5 patients with melanoma or renal cancer. Due to unacceptable toxicity at the 11,000 mg/m2 daily dose level, Carbetimer 8500 mg/m2 is the recommended dose for a 5-day treatment schedule every 28 days. Special attention should be directed toward possible activity against melanoma and renal cancer.

Adult↗
PubMed1990

Active-specific immunotherapy for melanoma.

Twenty-five patients with metastatic melanoma were treated with a therapeutic vaccine ("theraccine") consisting of allogeneic melanoma lysates and a novel adjuvant, DETOX (Ribi ImmunoChem Research, Inc, Hamilton, MT). Each patient received 200 antigenic units (20 x 10(6) tumor cell equivalents) subcutaneously on weeks 1, 2, 3, 4, and 6. Clinical responses included one complete remission, three partial remissions, and a long-term (17-month) stability. Two other patients had mixed responses, with partial remissions of numerous subcutaneous nodules. Sites of responsive disease included primarily the skin, but ileal, breast, and a liver metastasis also responded. Removal of residual lesions in patients with partial remissions, whose other lesions had disappeared during treatment, led to long disease-free survivals. The median duration of remission was 17 months, with four of the five responders alive for at least 24 months after treatment. An increase in precursors of cytolytic T cells (CTLs) correlated with clinical outcome, when complete, partial, and mixed responses and long-term stability were considered. The CTLs recognized melanoma-associated antigens on many cell lines, but not other types of tumor or normal lymphocytes. Skin-test reactivity to melanoma antigens and serum antibodies against the melanoma cells was unrelated to clinical response. Toxicity was minimal, restricted largely to minor soreness at the site of injection. Only five patients, four of whom were treated with repeated courses, developed severe granulomas. These results confirm that active-specific immunization with allogeneic lysates of melanoma administered with the adjuvant DETOX can induce immunity to melanoma, and can induce regressions of disease in a proportion of patients with metastatic disease with little toxicity.

Adjuvants, Immunologic↗
PubMed1990

Transient focal neurologic deficits complicating interleukin-2 therapy.

We report 2 patients with transient, focal, repetitive, stereotyped episodes of neurologic deficits during treatment with interleukin-2. One patient had recurrent monocular blindness, while the 2nd had recurrent homonymous quadrantanopia. We suggest that these attacks are provoked by endothelial cell activation induced by interleukin-2.

Blindness↗
PubMed1989

Tumor-reactive human immunoglobulin G monoclonal antibody from a melanoma patient.

To study tumor-associated antigens that are immunogenic to humans, we have generated human monoclonal antibodies by fusing lymph node lymphocytes of a melanoma patient with a mouse myeloma cell line. We examined in detail the reactivity of one IgG antibody, termed 2-139-1. Immunostaining was performed with purified antibody conjugated to biotin. Binding was visualized by the avidin-biotin-peroxidase complex. With cultured cells, 2-139-1 stained 12 of 12 melanomas and 12 of 16 carcinomas. Reactivity was not detectable in seven neural crest tumors, six sarcomas, and 45 lymphomas and leukemias. This spectrum of reactivity was confirmed with sections of human tissues. The human monoclonal antibody 2-139-1 reacted against melanomas and not banal nevi. While the antibody reacted strongly to adenocarcinomas of the colon, prostate, rectum, and pancreas, it did not stain all the carcinomas tested. Furthermore, reactivity was not seen against sarcomas. Interestingly, 2-139-1 did not bind to the majority of the cells in normal tissues, including fetal tissues. The reactivity of 2-139-1 may be representative of the humoral immune response found in the regional lymph nodes of cancer patients. The distribution of this epitope in various tumors was fairly limited and appeared to be associated with malignant transformation.

Antibodies, Monoclonal↗
PubMed1989

Human monoclonal antibodies reactive with colon carcinoma: identification by a novel screening procedure with xenografts.

To identify tumor-associated antigens immunogenic to man, human monoclonal antibodies (MAbs) were generated by fusing regional lymph node lymphocytes (LNLs) of each of three colon adenocarcinoma patients with the M5 mouse myeloma cell line. Heterohybridomas in 19 wells secreted human immunoglobulin (Ig) for at least 60 days. To identify immunoreactive MAbs, we devised an immunohistochemical assay with xenografts of six colon tumors. Binding was visualized with a biotin-conjugated goat antihuman Ig antibody followed by an avidin-biotin-peroxidase complex. This assay detected binding with a sensitivity of 0.5 microgram/ml human Ig. Reactivity against tumor-associated antigens (TAAs) in frozen sections of the colon xenografts was detected in 14 of the 19 supernates. However, only nine (three IgGs, five IgMs and one IgA) were reactive against formalin-fixed sections, showing that formalin-fixation destroyed some but not all antigenicity. Four MAbs were cloned and tested against the entire panel of 19 xenografts. One IgM MAb reacted only against colon carcinomas, while the other three (one each of IgA, IgG and IgM) had broader reactivities. Three of the four human MAbs did not cross-react with melanomas. In summary, human regional lymph nodes contain a high proportion of B lymphocytes sensitized to the autochthonous tumor. Immunostaining of human colon tumor xenografts can readily identify human MAbs reactive with colon carcinomas.

Animals↗
PubMed1989

Reactivity of a human monoclonal antibody against carcinomas and other lesions of the colon.

To identify tumor-associated antigens that may be immunogenic to man, human monoclonal antibodies (human mAb) were generated by fusing nonsecreting mouse myeloma cells with lymphocytes from regional mesenteric nodes of patients with adenocarcinomas of the colon. One IgG1 human mAb, designated as 14-31-10, was identified by its reactivity against human tumor xenografts. We have studied the reactivity of mAb 14-31-10 with formalin-fixed, paraffin-embedded specimens of human colon. A total of 86 cases were studied, including normal adult and fetal colons, adenocarcinomas of the colon, and a variety of colonic inflammatory diseases and preneoplastic lesions. Intense reactivity was found in 15 of 18 adenocarcinomas of the colon, but not in 10 specimens of normal adult or 4 specimens of fetal colonic mucosa. Interestingly, in four cases of carcinoma, reactivity was also observed in histologically normal mucosa situated 10 cm or more from the primary lesion. On the other hand, no staining was detected in any of the 16 inflammatory lesions. Of the 38 preneoplastic lesions, only 6 showed staining by the mAb: 1 of 5 benign tubular adenomatous polyps, 3 of 9 villous adenomas and tubovillous polyps, 1 of 5 specimens of ulcerative colitis and 1 of 19 specimens of familial polyposis. However, the intensity of staining was only moderate in those cases. Our data, therefore, suggest that the epitope identified by the human mAb 14-31-10 shows preferential expression in preneoplastic and neoplastic lesions of the colon, and in ostensibly normal mucosa at some distance from a primary colonic carcinoma. In all instances, the staining was cytoplasmic, suggesting a cytoplasmic or internal membrane location of the target antigen. This antigen appeared to be distinct from carcinoembryonic antigen, since staining by 14-31-10 was consistently different from that of a mouse monoclonal antibody to carcinoembryonic antigen in serial sections of the same specimens. The restricted reactivity of 14-31-10 suggests its potential application in immunohistochemistry. Moreover, the epitope identified by mAb 14-31-10 may be expressed during the progression of normal mucosa to neoplasia.

Animals↗
PubMed1989

Monoclonal antibody L/1C2 reactive with a human carcinoma associated antigen.

A murine IgG3 monoclonal antibody which defines a human carcinoma associated antigen is described. The antibody, designated L/1C2, was made against a human lung squamous cell carcinoma line designated USCLS-1. It reacts with the surface of 15 of 16 viable human carcinoma cell lines and was detected in 70 of 78 frozen sections of human carcinomas. Melanoma cell lines and frozen sections of melanomas and a lymphoma were unreactive. Normal tissue reactivity included vessels, plus some ducts, glandular structures, and epithelial surfaces. Similar normal tissue reactivity patterns were seen with Rhesus monkey tissue samples. Immunoprecipitation studies indicate that L/1C2 reacts with a glycoprotein doublet which migrates in the range of 110,000 to 140,000 Mr under reducing conditions. Fluorescence analysis suggests this antigen is internalized following reaction with the L/1C2 antibody. Using in vitro human tumor cell growth inhibition assays, it was possible to achieve significant growth inhibition with L/1C2, while another target cell-reactive antibody in the same assay had no inhibitory effect.

Adenocarcinoma↗
PubMed1989

Relapse in the central nervous system in melanoma patients successfully treated with biomodulators.

A number of partial or complete remissions have been induced within the past 3 years in patients with metastatic melanoma treated with biomodulators, such as low-dose cyclophosphamide (CY) and interleukin-2 (IL-2), or active specific immunotherapy. Six of the most successfully treated patients, with prolonged remissions in skin, lymph nodes, liver and/or lung, all had relapses in the brain. At the time of relapse in the CNS, remissions were continuing in the other viscera. A large single intracerebral metastasis was found in four of the six patients; the other two patients had three metastases each, one of which also had meningeal seeding. Resection was performed in the four patients with single lesions, without postoperative radiotherapy. Intrathecal IL-2 successfully controlled meningeal disease. To date, the median survival of the group exceeds 7 months, in contrast to the usual reported median of 1 to 4 months, reflecting the predominance of resectable single lesions. Immunological therapy failed to prevent or treat metastases to the CNS, but may have influenced the patients' reactivity to the disease, producing single rather than diffuse metastases. If melanoma is to be cured now by any systemic therapy, particularly biomodulation, new regional strategies must be devised to overcome the blood-brain barrier. By analogy with autoimmune disease of the CNS such as multiple sclerosis, in which excessive cell-mediated immunity is found, several possible immunological maneuvers are suggested.

Adult↗
PubMed1989

Low-dose cyclophosphamide and low-dose interleukin-2 for malignant melanoma.

We have studied the effects of low-dose recombinant interleukin-2 preceded by low-dose cyclophosphamide on malignant melanoma. Thirty eight outpatients aged from 25 to 75 years were treated with interleukin-2, 3.6 million Cetus units/m2 i.v. daily for five days on two successive weeks beginning three days after 350 mg/m2 of intravenous cyclophosphamide. This schedule was repeated at least twice more with a one-week interval between cycles, usually at the same dosage level. Ten of the 38 patients (26.3%) had clinically significant remissions: two complete (5.3%), seven partial (18.4%), and one ongoing, long-term (greater than 18 mo) "minor" response (2.6%). Four others (10.5%) had shorter minor responses and four (10.5%) a mixed response. One patient with disease restricted to the skin had a complete remission, while the other patient with a complete remission had had three lung nodules and an enlarged hilar lymph node. It was gratifying that one of the major sites of disease responding to treatment was the liver. Two complete and two partial remissions (i.e., greater than 50% regressions for greater than four weeks at this site) were obtained in 10 patients with liver involvement. Lung metastases also responded in four of 16 patients (one complete and three partial remissions). Subcutaneous nodules responded in seven of 21 patients (two complete, five partial remissions), while lymph node metastases diminished significantly in four of 14 patients (one complete, three partial remissions). The median duration of response was nine months (range, 1.5-20 months), with four patients treated for more than one year. Toxicity was moderate and controllable, and only two patients required hospitalization, both overnight. Lymphokine activated killer cell activation was induced in 24 of 38 patients, including all nine of the major responders. Conversely, none of 14 patients without lymphokine activated killer cell activation had a significant clinical remission. This regimen appeared to be as effective in melanoma as those involving ex vivo activation of lymphokine activated killer cells, and was more tolerable than therapy with high doses of interleukin-2.

Adult↗