Immunohistochemical phenotyping of human solid tumors with monoclonal antibodies in devising biotherapeutic strategies

Individually Specified Drug Immunoconjugates in Cancer Treatment

Forty-three patients with disseminated refractory malignancies each received an individually-specified combination of either Adriamycin (24 patients) or mitomycin-C (19 patients) conjugated murine monoclonal antibodies. Tumors were typed using a panel of antibodies with both immunohistochemistry and flow cytometry. Cocktails of up to six antibodies were selected based on binding greater than 80% of the malignant cells in the biopsy specimen. These monoclonal antibody cocktails were drug conjugated and administered intravenously.

Seventeen out of twenty-four patients had reactions to the administration of Adriamycin immunoconjugates, but these were tolerable in all but two patients. Fever, chills, pruritis and skin rash were by far the most common transitory reactions. All were well controlled with premedication. In several patients it was demonstrated that there was limited antigenic drift among various biopsies within the same patient over time. Up to 1 gram of Adriamycin and up to 5 grams of monoclonal antibody were administered. The limiting factor appeared to be a variable dissociation of active Adriamycin from the antibody which unpredictably caused hemopoietic depression.

Similar findings were noted in 19 patients with mitomycin-C conjugates. Thrombocytopenia at a 60mg dose of mitomycin-C in this schedule was dose limiting. Preliminary serological evidence suggests that the development of an IgM antibody which is specific against the mouse monoclonal antibody has the specificity and sensitivity to predict clinical reactions. These antibodies were quantitatively less in mitomycin-C patients.

Selected patients were re-treated. One patient with chronic lymphocytic leukemia had re-treatment on three occasions and demonstrated regression of peripheral lymph nodes. Two patients with breast carcinoma had definite improvement in ulcerating skin lesions and two patients with tongue carcinoma had shrinkage of their lesions. No responses were seen with mitomycin-C conjugates but binding was noted to tumors and colon with likely drug induced colitis seen after colon binding. This study demonstrates the feasibility and illustrates technical considerations in preparing drug immunoconjugate cocktails for patients with refractory malignancies.

Cocktail formulation and antibody delivery was accomplished. The major technical hurdle appears to be the selection of effective conjugation methods that can be used to optimally bind drugs to monoclonal antibodies for targeted cancer therapy.

Complementation of Expression of Carcinoembryonic Antigen and Tumor Associated Glycoprotein-72 (TAG-72) in Human Colon Adenocarcinomas

Enzyme-labeled monoclonal antibodies (MAbs) were used in an immunohistochemical, dual-staining study of 10 colon adenocarcinomas. MAbs B72.3 and COL-4, reactive with the high molecular weight tumor-associated glycoprotein-72 (TAG-72) antigen and carcinoembryonic antigen (CEA), respectively, were labeled with horseradish peroxidase or alkaline phosphatase. Dual staining using the two MAbs on a single tissue section (formalin-fixed, paraffin-embedded) showed that greater numbers of carcinoma cells could be detected by using the combination of the two MAbs than could be detected by use of either MAb alone. In many tumors, some carcinoma cells reacted with MAb B72.3, some reacted with MAb COL-4, and some cells reacted with both MAbs. Only 1 of 10 carcinomas showed > 75% reactive cells when stained with each MAb individually. In 9 of 10 cases, however, > 75% of cells reacted when the combination of MAbs was used. Cell surface and cytoplasmic patterns of reactivity were observed with both MAbs while some pools of extracellular mucin were composed of both TAG- 72 and CEA. This study supports the rationalefor the use of a combination of anti-TAG-72 and anti-CEA MAbs for in vitro immunologic detection and potential in vivo immunodiagnostic and immunotherapeutic applications for these MAbs in colon adenocarcinoma patients.

Molecular events associated with epithelial to mesenchymal transition of nasopharyngeal carcinoma cells in the absence of Epstein-Barr virus genome

Epithelial-mesenchymal transition (EMT) is an important process in tumor metastasis. The EMT-related events associated with metastasis of NPC in the absence of EBV have not been elucidated. We established an EBV-negative NPC cell line from a bone marrow biopsy of an NPC patient. Using a Matrigel system we isolated an invasive and non-invasive sublines, designated NPC-BM29 and NPC-BM00. NPC-BM29 acquired an invasive-like phenotype characterized by EMT, marked by down-regulation of E-cadherin and β-catenin with concomitant increased expression of Ets1. NPC-BM29 cells expressed ≥ 10-fold higher of MMP-9 than NPC-BM00 cells. NPC-BM29 cells grew better in 2% serum than NPC-BM00 cells, with a population doubling-time of 26.8 h and 30.7 h, respectively. A marked reduction in colony-formation ability of NPC-BM00 cells compared to NPC-BM29 was observed. Wound-healing assay revealed that NPC-BM29 cells displayed higher motility than NPC-BM00 and the motility was further enhanced by cell treatment with TPA, a PKC activator. Cell surface markers and tumor-associated molecules, AE3, MAK6 and sialyl-Tn, were up-regulated in NPC-BM29 cells, whereas the expression of HLA-DR and CD54 was significantly increased in NPC-BM00 cells. NPC-BM29 consistently released higher levels of IL-8 and IL-10 than NPC-BM00, with low levels of IL-1α expression in both cell lines. Higher level of VEGF production was detected in NPC-BM00 than NPC-BM29 cells. These data show that EBV is not required for exhibiting multiple metastatic phenotypes associated with EMT. More studies that target right molecules/signalings associated with the EMT may offer new therapeutic intervention options for NPC invasion and metastasis.

Antibody tumor penetration: transport opposed by systemic and antigen-mediated clearance

Antibodies have proven to be effective agents in cancer imaging and therapy. One of the major challenges still facing the field is the heterogeneous distribution of these agents in tumors when administered systemically. Large regions of untargeted cells can therefore escape therapy and potentially select for more resistant cells. We present here a summary of theoretical and experimental approaches to analyze and improve antibody penetration in tumor tissue.

Monoclonal antibody DS6 detects a tumor-associated sialoglycotope expressed on human serous ovarian carcinomas

A newly developed murine monoclonal antibody, DS6, immunohistochemically reacts with an antigen, CA6, that is expressed by human serous ovarian carcinomas but not by normal ovarian surface epithelium or mesothelium. CA6 has a limited distribution in normal adult tissues and is most characteristically detected in fallopian tube epithelium, inner urothelium and type 2 pneumocytes. Pre-treatment of tissue sections with either periodic acid or neuraminidase from Vibrio cholerae abolishes immunoreactivity with DS6, indicating that CA6 is a neuraminidase-sensitive and periodic acid-sensitive sialic acid glycoconjugate ("sialoglycotope"). SDS-PAGE of OVCAR5 cell lysates has revealed that the CA6 epitope is expressed on an 80 kDa non-disulfide-linked glycoprotein containing N-linked oligosaccharides. Two-dimensional non-equilibrium pH gradient gel electrophoresis indicates an isoelectric point of approximately 6.2 to 6.5. Comparison of the immunohistochemical distribution of CA6 in human serous ovarian adenocarcinomas has revealed similarities to that of CA125; however, distinct differences and some complementarity of antigen expression were revealed by double-label, 2-color immunohistochemical studies. The DS6-detected CA6 antigen appears to be distinct from other well-characterized tumor-associated antigens, including MUC1, CA125 and the histo-blood group-related antigens sLea, sLex and sTn.

Culture medium induced morphological changes of melanoma cells associated with change in sensitivity to lysis by lymphokine-activated killer cells

Three sublines (Clones 1, 2 and 7) of the human melanoma CaCL 73-36 cell line with different cellular morphology, growth patterns, melanin content and surface antigenic profile were maintained in RPMI-1640 medium plus 10% fetal bovine serum (abbreviated as RPMI). Each subline was divided into two groups: one grown in RPMI and the other in Dulbecco's modified Eagle's medium plus 10% fetal bovine serum (abbreviated as DMEM) for 96 h. Phenotypically, Clone 2 expressed Class I and II MHC and ICAM-1 on the surface and in the cytoplasm, while Clones 1 and 7 failed to express these antigens in both the cytoplasm and on the cell surface. Melanotic Clones 1 and 7 cells became even more pigmented, had slower growth rates, and exhibited lower saturation densities when incubated in DMEM than when they were incubated in RPMI. On the other hand, Clone 2 cells maintained in RPMI were grossly amelanotic, contained defective-like melanosomes detected ultrastructurally, and had distinct clusters of microvilli polarly located in most of the cells. Such specialized ultrastructures were not affected by medium conditions. Analysis of sensitivity of the clonal sublines to cytolysis by allogeneic effector cells revealed that in spite of low levels of natural killer (NK) cytotoxicity noted, DMEM produced a 2- to 14-fold increase in sensitivity to NK cells, irrespective of which medium was used. Different levels of lymphokine-activated killer (LAK) cytolytic activity were clearly observed in sublines maintained in RPMI, with Clone 2 being the most sensitive and both Clones 1 and 7 being less sensitive. Cells grown in DMEM exhibited significantly higher levels of sensitivity to LAK cytolysis than cells grown in RPMI as revealed by their differences in lytic units (p < 0.05). This was likely due to the high levels of surface ICAM-1 expression in cells incubated in DMEM vs little expression of this adhesion molecule by cells grown in RPMI. Taken together, these results demonstrate the presence of heterogeneous subpopulations within the CaCL 73-36 melanoma cell line regarding their pigmentary status, antigenic profile, growth pattern and responsiveness to NK/LAK cytolysis. The results also call attention to the importance of utilizing a same medium in short- and long-term cultures of melanomas for biological studies and response evaluations of therapeutic agents such as LAK cells, when multiple cell targets from different patients or multi-metastatic cell lines from individual patients are to be compared. Finally, these melanoma sublines may be valuable for further elucidation of the relationship between MHC expression, and increased sensitivity to LAK cytolysis, and the role of the components of DMEM in the mechanism for the observed induction of cell differentiation and enhanced LAK cytolysis.

The Cancer Biotherapy Research Group [CBRG], formerly the National Biotherapy Study Group [NBSG]: a 10-year perspective

The Cancer Biotherapy Research Group [CBRG], formerly known as the National Biotherapy Study Group [NBSG], celebrated its 10th anniversary in 1997. CBRG is a not-for-profit cancer clinical trials group of community oncologists whose activities for the most part have been funded by their associated community hospitals. From its inception the Group has focused on clinical investigations of biological agents in the treatment of patients with advanced cancer. This article reviews the history of the Group, its structure, accomplishments, and its current objectives and challenges.

Newly established MST-1 tumour cell line and tumour-infiltrating lymphocyte culture from a patient with soft tissue melanoma (clear cell sarcoma) and their potential applications to patient immunotherapy

The establishment and characterisation of paired autologous tumour cell line (MST-1) and tumour-infiltrating lymphocyte (TIL) culture from a tumour mass of a 14-year-old Taiwanese girl with soft tissue melanoma are described. MST-1 cells grown in vitro were heterogeneous in morphology, ranging from floating round cells, loosely attached round/oval or elongated cells with prominent pseudopod-like processes, to well-attached spindle and elongated dendritic cells without obvious pseudopods. Immunostaining revealed that major melanoma-associated antigens, such as S100 protein, HMB-45, melanotransferrin, chondroitin sulphate proteoglycan, and the gangliosides GD2 and GD3, were consistently expressed by the tumour tissue, severe combined immunodeficiency (SCID) mouse xenograft and derived cell lines. Flow cytometric analysis of the tumour DNA content showed an index of 1.8 relative to normal peripheral blood lymphocyte DNA. Chromosome analysis revealed all cells at a hypotetraploid level with several clonal chromosome aberrations, including deletions at 10p and 12q, an addition at 12q, translocations t(1;14) and t(5;6). Electron microscopy showed melanosome structures. This observation and the expression of the major melanoma-associated antigens were all indicative of the melanocytic origin of MST-1 tumour. Interleukin-2 (IL-2) expanded TILs had the predominant CD8+ phenotype and the capacity to lyse cells of the cultured autologous tumour. The availability of the soft tissue melanoma cell line, the SCID mouse xenograft tumour system as well as autologous TILs described herein would provide useful materials for identifying T-cell-defined antigens as well as a model system for devising individualised cancer biotherapeutic strategies. This cell line can also be used for further studies aimed at uncovering the histogenesis of this rare cancer.

Activation of human complement by totally human monoclonal antibodies

A uniquely developed series of totally human monoclonal antibodies (mAbs) were examined for their complement fixing properties in comparison to human myeloma preparations and to commercially available human polyclonal immunoglobulins. C3b and C4b deposition was measured using a kinetic ELISA technique. When the IgG myeloma proteins were tested for classical pathway activation, our findings were similar to those previously described, where IgG1 and IgG3 were more potent activators of the classical pathway than IgG2 and IgG4. However, those same studies determined that IgG2 was the best activator of the alternative pathway followed by IgG1 and IgG3 while IgG4 does not activate complement via either pathway. In our studies of alternative pathway activation, the IgG2 myeloma exhibited strong activation of the alternative pathway, but, at levels lower than the other three IgG subtypes. Using this test system, we examined the complement activating potential of four totally human mAbs that were constructed from the peripheral blood lymphocytes of a colon carcinoma patient in long term remission. We found that our uniquely constructed totally human IgG2 mAbs (A3, E1, F6 and F8) were able to activate complement by both the classical and alternative pathways to varying degrees. In addition, we found that the complement activating ability of the human mAbs was greater than that of the human IgG2 myeloma immunoglobulins or normal human IgG2 preparations. This study represents the first report of complement activation by totally human mAbs and confirms more recent findings which indicate that levels of complement activation by human IgG immunoglobulins cannot be predicted based solely on their subclass identity.

A microplate method for the determination of amino groups in monoclonal antibodies

The total number of amino groups in monoclonal antibodies can be estimated via a colorimetric assay using trinitrobenzene sulfonic acid (A.F.S.A. Habeeb (1966) Anal. Biochem. 14, 328-336). This work describes the adaptation of this method to a microtiter plate in order to rapidly and reliably assay large numbers of samples.

Tumor acquisition, propagation, and preservation. The culture of human colorectal cancer

Fourteen new colorectal cancer cell lines were developed as part of a tumor acquisition, propagation, and preservation program for biotherapy. Fifty-six specimens were received. Nine cell lines were generated from biopsies; seven of these cell lines were from metastatic lesions. Five additional cell lines were developed from xenografts grown in nude mice. Biopsies that produced three of these xenografts gave rise to parallel culture cell lines. Biopsy-derived and xenograft-derived cell lines from the same tumor behaved similarly in culture and exhibited similar markers when assessed immunohistochemically. Collagen substrate was beneficial in the primary culture of 50% of the specimens tested. Collagen was required for the successful propagation of two cell lines.