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R A Stahel

Publications and source records attributed to R A Stahel.

At least 91 records · Page 5Linked to original sources
PubMed1993

Antibodies to the protein core of the small cell lung cancer workshop antigen cluster-w4 and to the leucocyte workshop antigen CD24 recognize the same short protein sequence leucine-alanine-proline.

We recently described the identity of the small cell lung cancer (SCLC) cluster-w4 antigen and the human B cell differentiation marker CD24, a glycosylphosphatidylinositol (GPI)-anchored, highly glycosylated surface molecule of only 31-35 amino acids [15]. The specificities of three anti-cluster-w4 and of eleven anti-CD24 MoAbs have been investigated with respect to their binding capacity to the protein core of cluster-w4/CD24 antigen. Four overlapping peptides spanning this protein core were synthesized. MoAbs shown to bind to two overlapping peptides by antibody binding inhibition using the cluster-w4/CD24-positive SCLC cell line SW2 and by direct peptide binding detected in an ELISA were investigated in more detail. To determine the exact epitopes recognized by these MoAbs, an epitope mapping assay using peptides synthesized onto polyethylene pins was established. The three anti-cluster-w4 MoAbs SWA11, SWA21 and SWA22 and the anti-CD24 MoAbs OKB2 and ALB9 recognized the same short leucine-alanine-proline (LAP) sequence in an area without potential glycosylation sites close to the GPI anchor of the protein core of the cluster-w4/CD24 antigen.

Amino Acid Sequence↗
PubMed1992

CD24, a signal-transducing molecule expressed on human B cells, is a major surface antigen on small cell lung carcinomas.

Cell lines derived from human small cell carcinoma of the lung express high levels of a surface polypeptide termed the cluster-w4 antigen, which was previously identified as a potential target for toxin-based immunotherapy of lung cancer. We have cloned a complementary DNA encoding the cluster-w4 antigen from COS-1 fibroblasts transfected with a SW2 small cell carcinoma library, by panning with a mixture of the cluster-w4-specific monoclonal antibodies SWA11, SWA21, and SWA22. The sequence of the cluster-w4 complementary DNA encodes an unusually short (80-amino acid) protein identical to that recently reported for the leukocyte activation molecule CD24 except for a single valine-alanine substitution due to a single-base polymorphism within the region of the gene coding for the extracellular domain. Biochemical analyses of the cloned cluster-w4 antigen confirmed both the presence of the phosphatidylinositol tail and the extensive glycosylation reported for the CD24 molecule. Furthermore, the cloned cluster-w4 antigen expressed on COS cells was shown to react with a comprehensive panel of CD24-specific monoclonal antibodies, as assessed by indirect immunofluorescence staining. Northern blot hybridization indicated the presence of several transcript sizes for the cluster-w4 antigen that were greatly overexpressed in small cell carcinoma cell lines, compared with normal hemopoietic cells and CD24-positive cell lines. Southern blot hybridization of restriction digests of genomic DNA identified a complex pattern of bands consistent with either a complex gene structure containing many exons or the presence of a family of closely related genes.

Alanine↗
PubMed1992

Hematopoietic growth factors secreted by seven human pleural mesothelioma cell lines: interleukin-6 production as a common feature.

Seven mesothelioma cell lines, established from patients with pleural mesothelioma, exhibited substantial heterogeneity regarding in vitro morphology and growth characteristics. Media conditioned by these cell lines and by MeT5A normal mesothelial cells were examined for (i) colony formation on human bone-marrow cells, (ii) hematopoietic growth-factor content and (iii) mitogenic activity on mesothelioma cells. Colony-stimulating activity was produced only by the ZL34 cell line. Analysis of conditioned media by ELISA revealed that all mesothelioma cell lines constitutively produced IL-6, while the MeT5A normal mesothelial cells did not; in addition, GM-CSF and G-CSF were detected in the supernatant of the ZL34 cell line. Using a 3H-thymidine incorporation assay, we showed that all mesothelioma cell lines produced mitogenic activity in the culture supernatant, in contrast to the MeT5A normal mesothelial cells. The mitogenic effect of the hematopoietic growth factors detected in mesothelioma culture supernatants was tested on mesothelioma cells and on MeT5A normal mesothelial cells: IL-6, GM-CSF and G-CSF did not stimulate any DNA synthesis. Our results suggest that these hematopoietic growth factors do not act as autocrine growth factors. A common feature of this panel of mesothelioma cell lines is the production of IL-6; although the biological significance of the aberrant production of cytokines by mesotheliomas remains unclear, IL-6 might be involved in paraneoplastic syndromes such as thrombocytosis.

Granulocyte Colony-Stimulating Factor↗
PubMed1992

An autocrine mitogenic activity produced by a pleural human mesothelioma cell line.

The pleural human mesothelioma cell line ZL5 established in our laboratory exhibits an unusual phenotype with adherent and floating cells. ZL5 cells grow in a chemically defined medium (ACL3*) and can be maintained over 3 weeks in protein-free basal medium alone (RPMI). Basal medium conditioned by ZL5 cells possesses a mitogenic activity with an autocrine effect, as measured by cell counting and by a 3H-thymidine incorporation assay. Moreover, the conditioned medium affects the DNA synthesis of a variety of other lung-derived cells. The active principle of medium conditioned by ZL5 cells is not identical to the defined growth-factors EGF, PDGF, and TGF-beta, known to stimulate the growth of normal human mesothelial cells: treatment with these factors does not mimic the effect of conditioned medium on ZL5 cells. Our observations suggest that the mesothelioma cell line ZL5 produces an unknown autocrine mitogen.

Adenocarcinoma↗
PubMed1992

Tumor-antigen-specific humoral immune response of animals to anti-idiotypic antibodies and comparative serological analysis of patients with small-cell lung carcinoma.

We have previously developed 3 monoclonal anti-idiotypic antibodies (Ab2) of LOU rat origin directed against the binding site of the murine monoclonal IgM LAM8, which recognizes the small-cell lung carcinoma (SCLC)-associated sialoglycoprotein antigen sGP 90-135. The aim of this study was to compare the efficiencies of these 3 Ab2, designated LY8-229, LX8-531 and LX8-632, to induce antigen-specific immunity in different animal species without prior exposure of the recipients to the nominal antigen, and thereby possibly select an Ab2 candidate for active immunotherapy against SCLC in patients. The feasibility of this approach was further evaluated by a serological analysis of patients with SCLC compared with healthy individuals, in whom the spontaneous antibody reactivities against SCLC cell lines and Ab2 were tested. LY8-229 was shown to be the most effective Ab2 in inducing antigen-specific antibodies in BALB/c mice, CBA/J/Zur mice and one NZW rabbit. Furthermore, LY8-229 was the only Ab2 against which significantly elevated idiotype-specific antibody reactivities existed in sera of patients with SCLC. These reactivities correlated positively with binding to antigen-positive tumor cells. Our findings suggest that LY8-229 represents in its reactivity pattern the nominal SCLC antigen in humans also, and therefore may be of diagnostic and possibly therapeutic relevance for patients with SCLC.

Animals↗
PubMed1992

Cytotoxic properties of a ricin A chain immunotoxin recognising the cluster-5A antigen associated with human small-cell lung cancer.

The cytotoxic properties of a ricin A chain immunotoxin made with the mouse monoclonal antibody SWA20, recognising a family of sialoglycoprotein antigens selectively expressed by human small-cell lung cancer (SCLC), were examined using a panel of tumour cell lines in tissue culture. SWA20-ricin-A-chain was selectively toxic to the SW2, NCI-H69 and GLC-8 SCLC cell lines, inhibiting the incorporation of [3H]leucine by 50% at a concentration of 0.2-2 nM, but had no selective activity against the NCI-H23 and NCI-H125 lung adenocarcinoma or the control CEM T-lymphoblastoid cell lines. The SWA20 immunotoxin intoxicated the SW2 cell line rapidly, inhibiting [3H]leucine incorporation by 50% within 2 h compared with 0.5 h for ricin. Analysis of the effects of SWA20-ricin-A-chain on the growth of SW2 cells using a limiting-dilution clonogenic assay revealed that the immunotoxin could eliminate 95% of clonogenic malignant cells. Although SWA20-ricin-A-chain was found to be rapidly active against the majority of tumour cells, its action was limited by the presence of insensitive cells expressing low levels of the target antigen.

Antibodies, Monoclonal↗
PubMed1992

Molecular and biological properties of an abrin A chain immunotoxin designed for therapy of human small cell lung cancer.

An immunotoxin (IT) comprising abrin A chain attached to the mouse monoclonal antibody SWA11, recognising a cell surface antigen highly associated with human small cell lung cancer (SCLC), was synthesised using a hindered disulphide crosslinker, N-succinimidyl 3-(2-pyridyldithio) butyrate (SPDB), and purified by Blue Sepharose CL-6B affinity chromatography. The IT preparation contained monomeric conjugate, composed of one abrin A chain molecule linked to one SWA11 molecule, and was free from unconjugated A chain or antibody. The IT fully retained the cell-binding capacity of the antibody component and the ribosome-inactivating activity of the A chain. In cytotoxicity assays using the SW2 SCLC cell line in tissue culture, SWA11-SPDB-abrin A chain inhibited the incorporation of 3H-leucine by 50% at a concentration of 10 pM and by 99% at a concentration of 1 nM. The anti-tumour efficacy of the IT was tested in nude mice bearing established s.c. solid SW2 tumour xenografts. A single i.v. injection of SWA11-SPDB-abrin A chain at a non-toxic dose induced a significant 7 to 10 day growth delay that could not be matched by administration of equivalent doses of either unconjugated SWA11 or abrin A chain alone. The results of this study indicate that the antigen recognised by SWA11 is an effective target for therapy of SCLC with A chain ITs in vivo.

Abrin↗
PubMed1992

Potent cytotoxic action of the immunotoxin SWA11-ricin A chain against human small cell lung cancer cell lines.

The cytotoxic activity profile of an immunotoxin, SWA11-ricin A chain, recognising a cell-surface antigen associated with human small cell lung cancer (SCLC), was examined in detail using a panel of SCLC, non-SCLC and non lung tumour cell lines in tissue culture. SWA11-ricin A chain was potently and selectively active against three SCLC cell lines of both classic and variant morphologies, inhibiting the incorporation of 3H-leucine with an IC50 of 5 x 10(-11) M. At a concentration of 1 x 10(-8) M, the SWA11 immunotoxin could selectively eliminate in excess of 99.9% of clonogenic tumour cells. Intoxication proceeded rapidly following a 4 h lag phase; the initial rate of protein synthesis inhibition occurred with a t50 of 2 h and a t10 of 7 h. The cytotoxic activity of SWA11-ricin A chain was potentiated by 100-fold in the presence of the carboxylic ionophore monensin at 1 x 10(-7) M. Kinetic studies revealed that monensin enhanced the rate of protein synthesis inhibition by two-fold and eliminated the lag phase suggesting a rapid effect on either the rate or route of internalisation. Studies with SWA11 could detect no influence of monensin on the rate of antibody internalisation and a transient delay in the delivery of internalised antibody to lysosomes was observed by immunoelectron microscopy.

Antibodies, Monoclonal↗
PubMed1992

Chemotherapy with MACOP-B and VACOP-B for intermediate- and high-grade non-Hodgkin's lymphoma: clinical results and analysis of prognostic factors.

Eighty-three previously untreated patients with aggressive non-Hodgkin's lymphomas were treated with either MACOP-B (23 patients) or VACOP-B (60 patients) as originally described by Klimo and Conners [1, 2]. Their median age was 46 years. Thirty-seven patients had stage I or II and 46 stage III or IV disease. The tumor histopathology was reviewed in all cases. Sixty-five patients had intermediate grade and 18 high-grade non-Hodgkin's lymphomas according to the International Working Formulation. The rate of complete response was 74% for MACOP-B and 76% for VACOP-B. At the time of analysis the duration of follow-up was 50 months for the MACOP-B and 22 months for the VACOP-B group. The actuarial three-year progression-free survival was 35 +/- 10% for the MACOP-B group, 48 +/- 11% for the VACOP-B group, and 46 +/- 7% for all patients. Treatment mortality was 6%. A univariate and a multivariate analysis of selected pretreatment parameters and of regimen demonstrated that stage III or IV, high-grade lymphoma, and elevated serum LDH, but not the type of regimen, are significantly associated with poor progression-free survival in our patient population.

Adolescent↗
PubMed1992

Morphology, surface antigens, staging, and prognostic factors of small cell lung cancer.

Morphologic as well as biologic properties of small cell lung cancer change under chemotherapy toward a non-small cell and well-differentiated neuroendocrine phenotype. These biologic changes may be partly responsible for the acquisition of drug resistance. With the lack of significant advances with currently available chemotherapy, the development of new treatment strategies has become a major focus of research. Among others, these could include the use of antibodies to small cell lung cancer antigens. Several antigens associated with small cell lung cancer have now been biochemically and molecularly defined in the International Workshop of Small Cell Lung Cancer Antigens. In vitro and in vivo models have demonstrated the selective cytotoxic effect of immunoconjugates with radionuclides and plant toxins. Since recent clinical studies suggested a survival advantage for the use of radiotherapy in limited disease small cell lung cancer, anatomical staging to exclude distant sites of metastasis is likely to continue in clinical practice. Studies with a focus on cost-effective ways of anatomic staging are therefore of great importance. Continued efforts are under way to analyze pretreatment prognostic factors. The likely association of female gender with good prognosis and the in vitro data on stimulation of proliferation of small cell lung cancer cells by androgens may lead to the investigation of new therapeutic approaches based on endocrine manipulation.

Antigens, Neoplasm↗
PubMed1992

Potentiation of a weakly active ricin A chain immunotoxin recognizing the neural cell adhesion molecule.

A ricin A chain immunotoxin, SEN36-ricin A chain, directed against the neural cell adhesion molecule (N-CAM) had no selective cytotoxic activity against three different small cell lung cancer (SCLC) cell lines in tissue culture despite expression of the target antigen on more than 98% of cells in each line detected by indirect immunofluorescence. Treatment of the SW2 SCLC cell line with suramin and interferons alpha and gamma increased the level of N-CAM expression only slightly and had no significant effect on the cytotoxic activity of the SEN36 immunotoxin. In the presence of the carboxylic ionophore monensin at a concentration of 0.1 microM, the toxicity of SEN36-ricin A chain to the SW2 cell line was enhanced by 12,000-fold. In contrast, lysosomotropic amines showed little or no potentiation of activity, suggesting that lysosomal degradation was not the major factor limiting the action of the anti-N-CAM immunotoxin. The findings of this study indicate that ricin A chain immunotoxins directed against N-CAM on SCLC are unlikely to have sufficient activity to be useful therapeutic agents in the absence of potentiating agents such as monensin, which can interfere with the normal intracellular pathways of antigen routing.

Carcinoma, Small Cell↗
PubMed1991

Selective immunotherapy of small cell cancer xenografts using 131I-labelled SWA11 antibody.

Intact SWA11 antibody was evaluated as a potential radioimmunotherapeutic agent against small cell lung cancer xenografts in a nude mouse model system. 131I-labelled SWA11 was given either in a single injection regimen (1 x 300 microCi) or as a multiple injection regimen achieving a total of 900 microCi (3 x 300 microCi with a 2 week interval between injections). Treatment of both small (mean volume approximately 0.2 cm3) and large (mean volume approximately 1.0 cm3) established xenografts resulted in significant anti-tumour effects and, in the case of the fractionated protocol, the failure of the xenografts to regrow within the period of observation (84 days). Xenograft histology following radioimmunotherapy showed large areas of necrosis, fibrosis and very few residual cells of SCLC origin.

Animals↗
PubMed1991

Clinical and immune modulatory effects of alternative weekly interleukin-2 and interferon alfa-2a in patients with advanced renal cell carcinoma and melanoma.

The clinical and immune modulatory effects of interleukin-2 (IL-2) and interferon (INF) alfa-2a were examined in a phase II study in patients with metastatic renal cell carcinoma (six patients) and melanoma (eight patients). Treatment consisted in IL-2 3 MU/m2 continuous infusion days 1-4 and INF alfa-2a 6 MU/m2 subcutaneously day 1 and 4, both given on alternate weeks. Tumour response was assessed after four cycles of treatment or earlier, if necessary. Patients with stable disease or response were to be continued for another nine cycles or up to disease progression. The 14 patients received a total of 60 cycles of treatment. Major toxicities (WHO Grade III/IV) were fever, capillary leak syndrome with hypotension, nausea and vomiting, erythema with pruritus, leuco- and thrombopenia and sepsis with staphylococcus aureus. Five of 14 patients (36%) developed a self limiting autoimmune thyroiditis with HLA-DR expression on thyrocytes. Long term treatment toxicity was moderate with an average weight loss of 5% and an average fall in Karnofsky index of 10% compared to baseline. No responses were seen in renal cell carcinoma, two patients with melanoma had a partial and two a minor response with a duration of 1-7 months. Serial measurements of immune modulatory parameters showed a functional response to treatment with an increase of NK- and LAK-activity during the first two cycles, followed by a plateau and decrease during the third and fourth cycles. These findings were paralleled by a successive decline in treatment induced INF gamma response. These findings suggest, that alternative weekly treatment with IL-2 and INF alfa-2a results in an exhaustion of lytic capacity of NK- and LAK-cells and an attenuation of secondary cytokine release.

Adult↗
PubMed1991

Diagnosis, staging, and prognostic factors of small cell lung cancer.

The proportion of small cell-large cell or combined small-cell subtypes is very low, and the clinical outcome in patients with these subtypes appears not to be significantly different from that of the majority of patients with small-cell lung cancer. Anatomic staging of small-cell lung cancer remains necessary if the outcome influences treatment decisions and for treatment in many clinical trials. The influence of simple clinical and biochemical variables on prognosis has been confirmed by the analysis of very large numbers of patients. Patients with small-cell lung cancer surviving at 2 years after chemotherapy continue to be at risk for relapse for up to 5 more years independent of the initial stage of disease. Major future directions will include the investigation into possible correlations of biologic properties of tumors with prognosis and the use of simple clinical and biochemical parameters to preselect patients for treatment strategies according to risk groups.

Carcinoma, Small Cell↗
PubMed1991

Clinical experience with the combined use of recombinant interleukin-2 (IL2) and interferon alfa-2a (IFN alpha) in metastatic melanoma.

A multicentre study of IL2 and IFN alpha has been performed in 58 patients with metastatic melanoma. The scheme consisted of IL2 3.0 BRMP MU/m2/d as a continuous infusion for 4 d combined with subcutaneous administration of IFN alpha 6 MU/m2/d, day 1 + 4. The cycle was repeated every 2 weeks for a maximum duration of 26 weeks. 54 patients were evaluable for response. One (2%) achieved a complete and 10 (19%) a partial response. 19 (35%) patients were stable and 24 (44%) showed progressive disease. Common side-effects included fever, chills, fatigue, skin rash, anorexia, nausea and diarrhoea. Hypothyroidism was noted in 10% of the patients. These results show that this regimen of IL2 and IFN alpha is active but, in contrast to what could be expected, not superior to IL2 alone possibly due to suboptimal dosing. In an ongoing study in Rotterdam and Nijmegen, a more intense schedule was chosen, consisting of three daily i.v. doses of IL2 4.5 BRMP MU/m2 and IFN alpha 3.0 MU/m2 for 5 d. This regimen is repeated at intervals of 3 weeks for a total of three cycles. Presently, nine patients have been entered. One patient achieved a complete response, four a partial response (overall 56%), three had stable disease and one progressed. Toxicity was severe and treatment was prematurely stopped in five patients: myocardial infarction (one patient), atrial fibrillation (one patient), negative T waves and myocardial hypokinesia (one patient) and psychosis (two patients). This regimen can only be justified if the therapeutic results are superb, which has yet to be awaited.

Adolescent↗
PubMed1991

Monoclonal antibodies defining the cluster-5A small cell lung carcinoma antigen.

The cluster-5A antigen on small cell lung cancer has been previously identified by the murine IgG2a monoclonal antibody SWA20. We now describe four new murine monoclonal antibodies. SEN3 (IgG1), SEN11 (IgG3), SEN12 (IgG2b) and SEN31 (IgG1) which recognise the same antigen. The antibodies have similar binding characteristics as antibody SWA20 on cell lines and on a limited number of frozen sections of human tissues when examined by immunofluorescence and immunohistochemistry. Radioimmunoassays on fixed cells showed competitive binding of all antibodies with radiolabelled antibody SWA20. Solid phase radioimmunoassays with the new antibodies on biochemically treated target cells showed similar characteristics to antibody SWA20, including sensitivity to treatment with periodate and neuraminidase. Immunoblotting experiments with all antibodies revealed similar bands at molecular weights of 180, 100 and 50 kD. Binding studies after incubation of cells with inhibitors of glycoprotein synthesis suggest the cluster-5A antigen to be a N-linked sialoglycoprotein.

Antibodies, Monoclonal↗
PubMed1991

Modulation of neuroendocrine surface antigens in oncogene-activated small cell lung cancer lines.

Small cell lung cancer (SCLC) manifests a number of neuroendocrine differentiation features and antigenic characteristics that distinguish the tumour from non-small cell lung cancer (NSCLC). Several surface antigens on SCLC cells, identified by clusters of monoclonal antibodies (MAbs), distinguish SCLC and other neuroendocrine tumours of NSCLC. Stable transfection of the c-myc proto-oncogene has been reported to confer upon classic SCLC cells the growth properties and morphology of the variant subtype of SCLC (SCLC-v). Furthermore, insertion of the v-Ha-ras oncogene into such SCLC-v cells has been found to induce features typical of NSCLC. We have used classic SCLC cells transfected with c-myc, or co-transformed with c-myc and v-Ha-ras, to examine the expression of characteristics SCLC cluster antigens. Flow cytometric assays reveal that SCLC cells co-transformed with c-myc and v-Ha-ras oncogenes down-modulate SC-1, SC-2 and SC-5A surface antigens to levels approaching, in some cases, those seen with NSCLC cells. The SC-4 surface antigen is not modulated by activation of these oncogenes. These findings support clinical and laboratory observations that important transitions can occur between subtypes of human lung cancer cells, and that these shifts may play a role in the clinical progression of lung cancer.

Adenocarcinoma↗