Gamma-interferon enhancement of carcinoembryonic antigen expression in human colon carcinoma xenografts

Operative probe scintimetry with indium and technetium for colorectal cancer

Surgeons introduced the hand-held gamma detection probe in combination with tumor-directed monoclonal antibodies in patients with colorectal cancer. The clinicians conducted innovative research involving antibody chemistry and variation as well as radioactive dosimetry and decay. The results of these studies represented an era when surgeons began reporting on specific lesion detection and the impact of the antibody administration on the management of the patient. The summary of the important early trials involving monoclonal antibodies and probe scintimetry provides a valuable look into the early development of the antibody technology and a glimpse of potential future applications using the gamma detection probe.

Modulation of molecular mechanisms involved in protein synthesis machinery as a new tool for the control of cell proliferation

In the past years, the attention of scientists has focused mainly on the study of the genetic information and alterations that regulate eukaryotic cell proliferation and that lead to neoplastic transformation. All therapeutic strategies against cancer are, to date, directed at DNA either with cytotoxic drugs or gene therapy. Little or no interest has been aroused by protein synthesis mechanisms. However, an increasing body of data is emerging about the involvement of translational processes and factors in control of cell proliferation, indicating that protein synthesis can be an additional target for anticancer strategies. In this paper we review the novel insights on the biochemical and molecular events leading to protein biosynthesis and we describe their involvement in cell proliferation and tumorigenesis. A possible mechanistic explanation is given by the interactions that occur between protein synthesis machinery and the proliferative signal transduction pathways and that are therefore suitable targets for indirect modulation of protein synthesis. We briefly describe the molecular tools used to block protein synthesis and the attempts made at increasing their efficacy. Finally, we propose a new multimodal strategy against cancer based on the simultaneous intervention on protein synthesis and signal transduction.

Identification of HLA-A24 epitope peptides of carcinoembryonic antigen which induce tumor-reactive cytotoxic T lymphocyte

Carcinoembryonic antigen (CEA), which is expressed in several cancer types, is a potential target for specific immunotherapy. HLA-A24 is the most frequent allele among Japanese and is also frequently present in Asians and Caucasians. We tested CEA-encoded HLA-A24 binding peptides for their capacity to elicit anti-tumor cytotoxic T lymphocytes (CTL) in vitro. For this purpose, we used CD8+ T lymphocytes from peripheral blood mononuclear cells (PBMC) of a healthy donor and autologous peptide-pulsed dendritic cells as antigen-presenting cells. This approach enabled us to identify 2 peptides, QYSWFVNGTF and TYACFVSNL, which were capable of eliciting CTL lines that lysed tumor cells expressing HLA-A24 and CEA. The cytotoxicity to tumor cells by the CTL lines was antigen-specific since it was inhibited by peptide-pulsed cold target cells as well as by anti-class I major histocompatibility complex (MHC) and anti-CD3 monoclonal antibodies (MAbs). The antigen specificity of the 2 CTL lines was examined using several tumor cell lines of various origins and for their peptide-dose responses. The identification of these novel CEA epitopes for CTL offers the opportunity to design and develop epitope-based immunotherapeutic approaches for treating HLA-A24+ patients with tumors that express CEA.

Interferon-gamma enhances susceptibility of cervical cancer cells to lysis by tumor-specific cytotoxic T cells

Recently we have demonstrated that tumor-specific cytotoxic T lymphocytes (CTLs) can be activated by cervical carcinoma cells expressing the costimulatory molecule CD80, which may be used as a therapeutic vaccine for patients with cervical cancer. For activated CTLs to be effective, appropriate amounts of MHC class I expression are required on target tumor cells. In this study, we found that some cervical carcinoma cells expressed only low levels of MHC class I and adhesion molecules such as CD54. We further demonstrated that tumor cells (CaSki and SiHa) expressing low levels of MHC class I were more resistant to lysis by specific CTLs than tumor cells (HeLa) expressing high levels of MHC class I. Treatment of CaSki or SiHa cells with interferon-gamma resulted in an increased expression of MHC class I, MHC class II, and CD54. Expression of CD58 and CD80 was not up-regulated or induced. Treatment of the tumor cells with interferon-gamma significantly enhanced the lysis of the tumor cells by specific CTLs which had been activated by the respective CD80-expressing tumor cells. The enhancement of cytolysis could be blocked by monoclonal antibodies to MHC class I and CD54, but not by that to MHC class II. Furthermore, we found that interferon-gamma induced apoptosis in cervical carcinoma cells but not in tumor-specific CTLs.

Interferon alpha enhances expression of TAG-72 and carcinoembryonic antigen in patients with primary colorectal cancer

Interferons up-regulate the expression of human tumor-associated antigens in animal models and in vitro. The use of interferons may enhance the immunodetection and immunotherapy of tumors by monoclonal antibodies that detect tumor antigens. For this strategy to be effective, however, the interferon must have an effect at the site of the tumor. In this study, the induction by interferon alpha (IFN alpha) of two tumor surface antigens was evaluated in six patients with primary colorectal cancer. Patients were treated with IFN alpha and 48 h later underwent resection of the tumor. The interferon treatment induced expression of a tumor-associated glycoprotein (TAG-72) in two patients without antigen expression prior to interferon but had no effect on one TAG-72-negative tumor. IFN alpha did not induce expression of carcinoembryonic antigen (CEA) in the two patients whose tumors were CEA-negative prior to interferon. In all patients with heterogeneous expression of CEA and TAG-72 prior to IFN alpha treatment, preoperative interferon increased the percentage of cells positive for CEA in two patients and TAG-72 in one patient. This study supports the addition of interferon induction to immunotherapy regimens directed at the CEA and TAG-72 cell-surface antigens.

gamma-Interferon administration after 90yttrium radiolabeled antibody therapy: survival and hematopoietic toxicity studies

PURPOSE

Hematopoietic toxicity is the dose-limiting factor for radioimmunotherapeutic regimens. Cytokines have been shown to decrease hematopoietic toxicity in animals exposed to whole-body irradiation. The purpose of this study was to investigate the effects of murine gamma-interferon (gamma-IFN) on survival and hematopoietic toxicity in mice treated with high dose 90yttrium labeled anticarcinoembryonic antigen (CEA) monoclonal antibody.

METHODS AND MATERIALS

Balb/c nu/nu mice were injected intravenously with 250 Ci 90Y-T84.66 (a murine anti-CEA monoclonal antibody). Thirty thousand units of gamma-IFN was administered i.v. 24 h later. Control mice received either 250 Ci 90Y-T84.66 alone or 30,000 units gamma-IFN alone. Survival, antibody biodistribution, and bone marrow histologic studies were then performed.

RESULTS

Only 7% of the animals treated with 90Y-T84.66 survived up to 40 days posttreatment, when the study was terminated. In contrast, 52% of the mice treated with both 90Y-T84.66 and gamma-IFN survived 40 days posttherapy. No toxic deaths were seen in the control group administered gamma-interferon alone. Histologic examination of the bone marrow of animals receiving 90Y-T84.66 and gamma-IFN showed cellular depletion of 40-70% of the hematopoietic cells by 48 h. Cell depletion was 50-70% and 20% by 72 h and 8 days posttherapy, respectively. The marrow of the 90Y-T84.66-treated control group was depleted to a level of 50-80% at 48 h, and remained depleted at 90% at 72 h and 8 days posttherapy. No marrow cell reduction was seen in the gamma-IFN-only treated group. Biodistribution studies showed no alterations in antibody biodistribution or kinetics that could account for the changes in bone marrow toxicity after gamma-IFN.

CONCLUSION

These results demonstrate that gamma-IFN can reduce the hematologic toxicity resulting from high dose radioimmunotherapy. Histologic studies of bone marrow suggest that gamma-IFN acts primarily to accelerate myelorestoration of the bone marrow. Further studies exploring the use of gamma-IFN as an adjunct to radioimmunotherapy are therefore warranted.