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

Abstract

A panel of 14 monoclonal antibodies (MoAbs) (4 raised against breast cancer, 6 against colon cancer and 4 against melanoma) were used to phenotype frozen sections of tumor biopsies obtained from 110 patients, by avidin-biotin-peroxidase complex techniques. We observed heterogeneity of antigen expression among the multiple metastatic lesions of single patients, as well as among tumor lesions from different patients with similar tumor histotypes. A wide range of cross-reactivity of anti-(breast-carcinoma) and anti-(colon-carcinoma) MoAbs with other carcinoma histotypes and limited reactivity with melanoma and sarcoma was detected. Some of our anti-melanoma MoAbs were also found to cross-react with selected carcinomas. Nine of the 14 MoAbs most reactive with carcinomas of diverse histotypes have been identified. A mixture or 'cocktail' of different MoAbs could be selected for each individual patient in order to achieve binding of MoAbs with most, if not 100% of tumor cells. This study illustrates the approach that we have taken to individualize the cocktail of MoAbs for the development of patient-specific therapeutic immunoconjugates.

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

“…Heterogeneous antigen expression may also reduce therapeutic efficacy as non-antigen expressing cells will be left untargeted even if the saturation criteria (Γ<1, φ 2 <1) are achieved [100]. Combinations of antibodies against different antigens or therapeutics capable of initiating bystander effects may improve therapeutic efficacy in these cases [101,102].…”

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

“…Double-label, 2-color, sequential IH studies comparing CA6 to CA125 demonstrated that MAbs DS6 and OC125, while showing extensive overlap, also show areas in which only 1 is expressed, providing additional, complementary coverage of the tumor. Such complementarity of TAA expression can have important clinical implications, whether for tailoring MAb-based cancer therapies as "cocktails" matched to a given tumor's antigenic phenotype (Liao et al, 1989;Oldham, 1991) or for devising panels of tumor markers to monitor tumor progression (Cane et al, 1995).…”

Human tumor and normal tissue reactivity of the anti-(breast cancer) monoclonal antibody BA-Br-3 and its similarity to the anti-(epithelial membrane antigen) monoclonal antibody E29

“…The additional breast tumor lines (BRXBr4 and BRXBrl) and two colon tumor lines (BRXCo6 and BRXCo3X) were established in our laboratory [26]. [30]. All cells were grown as monolayers in RPMI-1640 medium (Gibco, Grand Island, NY) with 10% heat-inactivated fetal bovine serum without antibiotics, The cultures were monitored for mycoplasma contamination using the Genprobe system (Gibco) and were found to be free of mycoplasma during the course of this study.…”

“…Test antibody samples (5 ~tg/ml and 10 gg/tal) were added (100 gl/tube) and incubated for 30 min at 4°C. Immunofluorescent staining and flow cytometry were performed according to procedures previously described [30].…”

“…We have recently generated a murine mAb, BA-Br-3, raised against cell lysates prepared from the breast carcinoma cell line, CAMA-1 [27,30]. Using mixed hemadsorption assays, we have initially shown that this antibody reacts with carcinoma cell lines of diverse origin but not with neuroectodermal tumor cell lines.…”