Patricia Horan Hand

Expression of ras Oncogene p21 in Prostate Cancer

The major neoplastic transformation-inducing genes of human solid tumors are members of the ras oncogene family. We used an immunohistochemical assay to assess expression of both the unaltered and the mutated ras oncogene protein (p21) in normal and neoplastic prostatic cells. With the concentration of monoclonal antibody used in this study, epithelial and stromal cells from subjects with normal prostates and from 19 patients with benign prostatic hyperplasia were negative for p21 antigen. This antigen was detected in 2 of 6 prostates with Grade I carcinoma, 4 of 6 with Grade II, and all of 17 with higher grades. A semiquantitative immunohistochemical method demonstrated that expression of the p21 antigen in a carcinoma strongly correlated with nuclear anaplasia and was inversely related to the degree of glandular differentiation. However, markedly anaplastic tumors were often more heterogeneous in expression of p21 and contained areas of low staining for the antigen. Comparison of p21 antigen with tumor carcinoembryonic antigen and prostate-specific antigen demonstrated that ras p21 was the only phenotypic marker that correlated with histologic tumor grade. Thus, ras oncogene p21 may represent a new class of biologically relevant tumor markers and may be a useful adjunct to histopathologic examination in determining the prognosis of patients with prostate cancer.

Anti-Tumor Activity of Human T Cells Expressing the CC49-zeta Chimeric Immune Receptor

A chimeric immune receptor consisting of an extracellular antigen-binding domain derived from the CC49 humanized single-chain antibody, linked to the CD3zeta signaling domain of the T cell receptor, was generated (CC49-zeta). This receptor binds to TAG-72, a mucin antigen expressed by most human adenocarcinomas. CC49-zeta was expressed in CD4+ and CD8+ T cells and induced cytokine production on stimulation. Human T cells expressing CC49-zeta recognized and killed tumor cell lines and primary tumor cells expressing TAG-72. CC49-zeta T cells did not mediate bystander killing of TAG-72-negative cells. In addition, CC49-zeta T cells not only killed FasL-positive tumor cells in vitro and in vivo, but also survived in their presence, and were immunoprotective in intraperitoneal and subcutaneous murine tumor xenograft models with TAG-72-positive human tumor cells. Finally, receptor-positive T cells were still effective in killing TAG-72-positive targets in the presence of physiological levels of soluble TAG-72, and did not induce killing of TAG-72-negative cells under the same conditions. This approach is being currently being utilized in a phase I clinical trial for the treatment of colon cancer.

The use of a rapid ELISPOT assay to analyze peptide-specific immune responses in carcinoma patients to peptide vs. recombinant poxvirus vaccines.

Abstract An enzyme-linked immunosorbent spot (ELISPOT) assay for interferon γ production has been used to analyze specific T cell responses to a Flu 9-mer peptide, and a 9-mer peptide of carcinoembryonic antigen (CEA). Assays were performed on peripheral blood mononuclear cells (PBMC) of HLA-A2-positive patients with CEA-expressing carcinomas, both before and after vaccination with CEA-based vaccines, and from HLA-A2-positive healthy blood donors. The ELISPOT assay utilized aliquots of frozen PBMC, and assays were performed after 24 h in culture with peptide to rule out any artifacts due to long-term in vitro stimulation cycles. An internal standard was used for each assay to define reproducibility of the assay, and all samples from a given patient (pre- and post-vaccination, with both the Flu and CEA peptides) were analyzed simultaneously. The results indicated a trend towards healthy blood donors having higher levels of Flu-specific T cell precursors than do colon carcinoma patients, but these results were not statistically significant (P = 0.06). On the other hand, slightly higher CEA-specific T cell responses were observed in cancer patients with CEA-expressing carcinomas than in healthy blood donors. PBMC from two CEA-based vaccine clinical trials were analyzed for T cell responses to the same CEA peptide and to the Flu control peptide. The first trial consisted of three monthly vaccinations of CEA peptide (designated PPP) in adjuvant. The second trial consisted of cohorts receiving three monthly vaccinations of avipox-CEA recombinant (designated AAA) or cohorts receiving a primary vaccination with recombinant vaccinia-CEA followed by two monthly vaccinations with avipox-CEA (designated VAA). Few, if any, CEA-specific T cell responses were seen in the PPP vaccinations, while the majority of patients receiving the poxvirus CEA recombinants demonstrated increases in CEA-specific T cell responses and no increases in Flu-specific responses. CEA-specific IgG responses were also demonstrated in patients following recombinant CEA poxvirus vaccinations. Statistical analyses of the T cell responses to the same CEA peptide demonstrated a P value of 0.028 for the recombinant poxvirus vaccines, as compared with the peptide vaccine. There were no differences seen (P = 0.37) in Flu-specific responses after these two types of CEA vaccination. These results thus provide the first evidence that poxvirus recombinant-based vaccines are more potent in the initiation of tumor-antigen-specific T cell responses than vaccines employing peptide in adjuvant, when assays are conducted in an identical manner, and in defining responses to the same peptide. These results also demonstrate for the first time that an ELISPOT assay, performed over a 24-h period and without in vitro sensitization, can be successfully used to monitor immune responses to a tumor-associated antigen in cancer patients.

Differential Binding to Human Mammary and Nonmammary Tumors of Monoclonal Antibodies Reactive with Carcinoembryonic Antigen

Splenic lymphocytes of mice immunized with membrane enriched fractions of human mammary carcinomas were fused with the NS-1 nonsecretory++ myeloma cell line. The resulting hybridomas were screened for the synthesis of immunoglobulins reactive with human mammary tumor associated antigens, and two IgG monoclonal antibodies (B1.1 and F5.5) were identified as being reactive with purified carcinoembryonic antigen (CEA). These antibodies were shown to bind to different epitopes on CEA based on their differential reactivities to five different purified CEA preparations, and their differential binding to the surface of tumor cells derived from various organ sites. Monoclonal B1.1 bound equally to the surface of human breast, colon, and melanoma cell lines. Monoclonal F5.5, on the other hand, did not react with the surface of melanoma cell lines, and showed a differential binding to breast carcinoma versus colon carcinoma cells. Monoclonals F5.5 and B1.1 were both used in immunoperoxidase studies with fixed tissue sections of a variety of histologic types of human mammary carcinomas and were shown to be reactive with 55% and 66%, respectively, of tumor masses.

Monoclonal Antibodies Reactive With Breast Tumor-Associated Antigens

Publisher Summary Monoclonal antibodies (MAbs) led to the identification of novel tumor-associated antigens (TAAs) from various human carcinomas, melanomas, leukemias, and lymphomas. There are approximately two dozen characterized monoclonals reactive with human breast tumors. Several of these are chosen to elaborate those phenomena that are most relevant for the use of MAbs in the management of human breast cancer as well as in the study of the biology of human mammary carcinoma cell populations. This chapter describes numerous MAbs that are reactive with human mammary carcinomas. They can be classified into four groups based on the immunogen used to generate the MAb. These include using breast tumor cell lines, milk fat globule membrane, and membrane-enriched extracts of breast carcinoma metastases as immunogen, and lymph nodes from mastectomy patients. Each of the MAbs, including those prepared by several different groups to milk fat globule membrane, appears to be unique with respect to percentage of reactive mammary tumors, percentage of reactive cells within tumors, location of reactive antigen within the tumor cell, or degree of reactivity with nonmammary tumors as well as normal tissues.

Comparative biological properties of a recombinant chimeric anti-carcinoma mAb and a recombinant aglycosylated variant

SummaryIt has been demonstrated previously that the degree of glycosylation of a molecule may alter its pharmacokinetic properties and, in the case of an antibody, its metabolism and other biological properties. Transfectomas producing aglycosylated chimeric B72.3(γ1) pancarcinoma monoclonal antibody (mAb) were developed by introduction of the eukaryotic expression construct pECMgpB72.3 HuG1-agly, into SP2/0 murine myeloma cells producing the chimeric κ chain of mAb B72.3. After cell cloning, one subclone with the highest binding to the TAG-72-positive human colon carcinoma was designated mAb aGcB72.3, and its biological and biochemical properties were compared with those of the chimeric B72.3(γ1), designated mAb cB72.3. Polyacrylamide gel electrophoresis showed that under non-reducing conditions, the molecular masses of the aGcB72.3 and cB72.3 mAbs were 162 kDa and 166 kDa respectively. The heavy chain of mAb aGcB72.3 had a slightly faster mobility than that of cB72.3, while the mobility of the light chains of the two chimeric mAbs was similar. No difference was observed in the isoelectric points of either chimeric mAb. Liquid competition radioimmunoassays demonstrated that the aGcB72.3 and cB72.3 mAbs have comparable binding properties to TAG-72. These studies demonstrate that aglycosylation of the chimeric IgG1 mAb B72.3 at theCh2 domain, as has been shown for other mAbs [Dorai H., Mueller B., Reisfeld R. A., Gillies S. D. (1991) Hybridoma 10:211; Morrison S. L., Oi V. T. (1989) Adv Immunol 44:65], eliminates antibody-dependent cell-mediated cytotoxicity activity, but does not substantially alter affinity or plasma clearance in mice. These studies also demonstrate for the first time (a) no difference in plasma clearance of an aglycosylated and a chimeric mAb in a primate after i.v. inoculation; (b) a difference (P ⩽0.05) in mice in the more rapid peritoneal clearance of a chimeric mAb versus an aglycosylated chimeric mAb; (c) higher (0.05 ⩽P ⩽0.1) tumor:liver ratios at 24, 72 and 168 h using111In-labeled aglycosylated chimeric mAb versus chimeric mAb. Since the liver is the major site of metastatic spread for most carcinomas, slight differences in tumor to normal liver ratios may be important in diagnostic applications. These studies thus indicate that comparative analyses of a novel recombinant construct (i.e., aglycosylated) and its standard chimeric counterpart require documentation in more than one system and are necessary if one is ultimately to define optimal recombinant/chimeric constructs for diagnosis and therapy in humans.

Evaluation of human carcinoembryonic-antigen (CEA)-transduced and non-transduced murine tumors as potential targets for anti-CEA therapies

The MC-38 C57BL/6 mouse colon adenocarcinoma cell line has been transduced with a retroviral construct containing cDNA encoding the human carcinoembryonic antigen (CEA) gene [Robbins PF, Kantor JA, Salgaller M, Horan Hand P, Fernsten PD, Schlom J (1991) Cancer Res 51: 3657]. Two clones, MC-38-ceal and MC-38-cea2, expressed high levels of CEA on their cell surface. A third CEA-expressing cell line, MCA-102-cea3, was similarly derived by transduction of the MCA-102 C57BL/6 mouse fibrosarcoma cell line and is described here. In this study, the three CEA-transduced murine tumor cell lines (MC-38-cea1, MC-38-cea2, MCA-102-cea3) were evaluated for their tumorigenic potential, as well as their ability to serve as in vivo model systems for active and passive immunotherapy studies. Parameters that were investigated include tumor growth rate, the antibody response of the host to CEA, and the CEA content of the tumors. The MC-38-cea2 model appeared to be the most appropriate for immunotherapy studies. Biodistribution studies, using an125I-labeled anti-CEA mAb, demonstrated efficient tumor targeting of MC-38-cea2 tumors in C57BL/6 and athymic mice.

Potential for recombinant immunoglobulin constructs in the management of carcinoma.

Background. Numerous monoclonal antibodies (MoAb) have been developed and currently are being evaluated in both diagnostic and therapeutic clinical trials. Despite the major advances fostered by MoAb technology, several limitations inherent to the use of MoAb exist. For example, MoAb may not have the desired plasma pharmacokinetics and metabolic properties, and they may be immunogenic, thus reducing the possibility of numerous administrations.

Interspecies radioimmunoassay for the major internal protein of mammary tumor viruses.

Abstract An interspecies radioimmunoassay has been developed which detects antigenic determinants shared by type-B mammary tumor viruses (MTVs). This interspecies assay is specific for antigenic sites which the 28,000-dalton major internal protein of MMTVs of laboratory mice (Mus musculus) has in common with polypeptides of MC-MTV. MC-MTV is a new type-B retrovirus isolated from the Asian rodent, Mus cervicolor ( J. Schlom, P. H. Hand, Y. A. Teramoto, R. Callahan, G. Todaro, and G. Schidlovsky, 1978 , J. Nat. Cancer Inst. 61, 1509–1519). Other retrovirus isolates of Mus cervicolor, i.e., M432, CERV-CI, and CERV-CII, as well as other type-C and type-D retroviruses, do not compete in the interspecies assay. The interspecies assay detected MTV cross-reactive antigenic determinants with equal efficiency in milks, lactating mammary glands, and in spontaneous mammary tumors of three distinct species. Particles morphologically indistinguishable from MMTV and MC-MTV have also been detected in Mus cookii mammary tumor cells. The interspecies MTV p28 radioimmunoassay thus provides a potentially useful tool for the detection of etiologically related viruses or viral translational products in species other than the laboratory mouse.

TAG-72 as a Tumor Marker

In 1981, the murine IgG monoclonal antibody (MAb) B72.3 was isolated. The immunogen employed was a membrane-enriched fraction of human mammary carcinoma metastasis (Colcher et al., 1981). The B72.3-reactive antigen has subsequently been purified and characterized and has been termed TAG-72, for tumor-associated glycoprotein (Johnson et al., 1986). As a result of the purification of TAG-72, a second generation of anti-TAG-72 MAbs has been generated and characterized (Muraro et al., 1988); because the TAG-72 was obtained from a human colon cancer xenograft (LS-174T), these second-generation MAbs have been given the designation CC (i.e., CC49 and so on).