Immunotherapy of tumor-bearing mice utilizing virus help

Follow-up analysis of a randomized phase III immunotherapeutic clinical trial on melanoma

Development of a melanoma-specific vaccine is of clinical necessity. Therefore, a phase III, randomized, double-blind trial was performed (June 1988-June 1991) to assess the clinical effectiveness of our vaccinia melanoma oncolysate (VMO) vaccine in stage III melanoma patients. Patient data were collected from 11 institutions, as well as from the Social Security Death Index and were analyzed from April through August 2008 for disease-free interval (DFI) and overall survival (OS). The median OS for patients who were administered the VMO vaccine was 7.71 years, compared to 7.95 years for patients administered the vaccinia virus vaccine (V) (p=0.70). The median DFI for the VMO group was six years, while the median DFI for the V group has not yet been reached. This analysis demonstrated a statistically significant difference in OS in females in both groups (VMO, 79%; V, 92%), as compared to males (VMO, 57%; V, 68%) (p=0.0473). This follow-up analysis demonstrated that females had a survival advantage over males, thus warranting further investigation. This significant observation may facilitate the recruitment of patients for future clinical trials, as well as determine which patients are more likely to benefit from receiving the VMO vaccine.

Oncolytic vaccinia virus: a theranostic agent for cancer

Vaccinia virus (VACV) is arguably the most successful live biotherapeutic agent because of its critical role in the eradication of smallpox, one of the most deadly diseases in human history. VACV has been exploited as an oncolytic therapeutic agent for cancer since 1922. This virus selectively infects and destroys tumor cells, while sparing normal cells, both in cell cultures and in animal models. A certain degree of therapeutic efficacy also has been demonstrated in patients with different types of cancer. In recent years, several strategies have been successfully developed to further improve its tumor selectivity and antitumor efficacy. Oncolytic VACVs carrying imaging genes represent a new treatment strategy that combines tumor site-specific therapeutics with diagnostics (theranostics).

The treatment of melanoma with an emphasis on immunotherapeutic strategies

Melanoma continues to be one of the most difficult to treat of all solid tumors. Many new advances have been made in the surgical management of melanoma, including new guidelines for margins of excision, as well as sentinel node biopsy for the diagnosis of lymph node micrometastases. The search continues for an effective adjuvant melanoma treatment that can prevent local and distant recurrences. Melanoma is one of the most immunogenic of all tumors, and several clinical trials testing the immunotherapy of melanoma have been conducted, including trials in interferon, interleukin-2, and melanoma vaccines. Here we discuss many of the recent clinical trials in the surgical management of melanoma, in addition to the advances that have been made in the field of immunotherapy. A new second-generation melanoma vaccine, DC-MelVac (patent # 11221/5), has recently been granted FDA approval for Phase I clinical trials and will be introduced in this review.

Membrane-bound complement regulatory activity is decreased on vaccinia virus-infected cells

Decay accelerating factor (DAF), membrane cofactor protein (MCP), complement receptor 1 and mouse Crry are cell surface-bound complement regulatory proteins capable of inhibiting C3 convertase activity on cell membranes, and therefore provide a substantial protection from attack by homologous complement activated either by the classical or by the alternative pathway. Decrease in complement regulatory activity might lead to spontaneous complement deposition and subsequent cell injury. MoAb 5I2 can inhibit the complement regulatory activity of molecules on rat cells, resulting in deposition of homologous complement. The antigen recognized by 5I2 MoAb in rats is homologous to mouse Crry. Fifteen to 20 h after infection with vaccinia virus, in vitro cultured KDH-8 rat hepatoma cells show a strong decrease in expression of Crry-like antigen, and proved to be sensitive to complement deposition when 1:5 diluted normal rat serum was added to the culture medium as a source of complement. Addition of complement to the cultured KDH-8 cells infected with a very low dose of vaccinia virus (1 plaque-forming unit (PFU)/1000 cells) substantially reduced spreading of virus infection in the cell culture, while inactivation of complement by heat or zymosan treatment abrogated the protective effect.

Establishment of cytotoxic CD4+ T cell clones from cancer patients treated by local immunotherapy

We have previously reported that the antitumor effect of OK-432, a Streptococcal preparation, is markedly augmented when injected intratumorally together with fibrinogen (Cancer, 69: 636-642, 1992). In order to elucidate the mechanism of the antitumor effects, we established T cell clones from regional lymph nodes of colorectal cancer patients who received this local immunotherapy. By culture of lymph node lymphocytes, in the presence of IL-2 and OK-432, 4 clones of T cells were established from 4 patients treated by local immunotherapy. These clones had a helper T cell phenotype (CD3+, CD4+, CD8-, CD56-, WT31+) and were successfully maintained for several months. The cells strongly expressed CD25 when stimulated with OK-432 and exhibited a high level of cytotoxic activity in part explained by the increased expression of ICAM-1 and LFA-1, and the release of TNF beta. These results suggest that the CD4+ T cells play a role in the antitumor mechanism of local immunotherapy.

Persistent measles virus infection enhances major histocompatibility complex class I expression and immunogenicity of murine neuroblastoma cells

The effect of persistent measles virus infection on the expression of major histocompatibility complex (MHC) class I antigens was studied. Mouse neuroblastoma cells C1300, clone NS20Y, were persistently infected with the Edmonston strain of measles virus. The persistently infected cell line, NS20Y/MS, expressed augmented levels of both H-2Kk and H-2Dd MHC class I glycoproteins. Activation of two interferon(IFN)-induced enzymes, known to be part of the IFN system: (2'-5')oligoadenylate synthetase and double-stranded-RNA-activated protein kinase, was detected. Measles-virus-infected cells elicited cytotoxic T lymphocytes that recognized and lysed virus-infected and uninfected neuroblastoma cells in an H-2-restricted fashion. Furthermore, immunization of mice with persistently infected cells conferred resistance to tumor growth after challenge with the highly malignant NS20Y cells. The rationale for using measles virus for immunotherapy is that most patients develop lifelong immunity after recovery or vaccination from this infection. Patients developing cancer are likely to have memory cells. A secondary response induced by measles-virus-infected cells may therefore induce an efficient immune response against non-infected tumour cells.

Augmentation of antimetastatic effect on Lewis lung carcinoma (3LL) in C57BL/6 mice by priming with Lactobacillus casei

The augmentation of the antimetastatic effect of heat-killed cells of Lactobacillus casei YIT9018 (LC9018) on Lewis lung carcinoma (3LL) in C57BL/6 mice by presensitization (priming) with LC9018 was examined. Intralesional injection of LC9018 into 3LL-bearing mice inhibited both the growth of the primary tumors and the formation of lung metastases, and this effect was significantly augmented by subcutaneous injection of LC9018 before the tumor inoculation. In the LC9018-primed mice, intraperitoneal administration of LC9018 into syngeneic hosts after priming induced a high level of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) in the peritoneal cavity. At this time, T cells of the spleen cells from the LC9018-primed mice proliferated and produced IL-2 when co-cultured with LC9018 as antigen in vitro. Also, the phenotype of these T cells was found to be L3T4+ and Ly-2.2- T cells by analysis by flow cytometry. These results suggest that LC9018-reactive helper T (Th) cells were induced by the priming and subsequent challenge with LC9018, and that IL-2 or IFN-gamma, which was produced by the activated LC9018-reactive Th cells, augmented a host immune response resulting the antitumor activity.

Active specific immunotherapy with vaccinia colon oncolysate enhances the immunomodulatory and antitumor effects of interleukin-2 and interferon alpha in a murine hepatic metastasis model

The role of cytokines as primary or adjuvant antineoplastic agents has been well established. Interleukin-2 (IL-2) and the interferons have, particularly, proven to be effective antitumor agents when given alone, and seem to act synergistically on the eradication of metastases from immunogenic tumors. Active specific immunotherapy, in the form of viral oncolysates, has also shown effectiveness in cancer therapy. Bearing this in mind, we decided to combine these agents in an adjuvant triple regimen and compare their effectiveness to other treatments in terms of tumor burden and survival in a murine colon cancer hepatic metastases model. BALB/c mice were injected with CC-36, a weakly immunogenic murine colon adenocarcinoma, intrasplenically, to produce artificial liver metastases. The animals were divided into one control group and seven treatment groups receiving either vaccinia colon oncolysate (VCO), IL-2, interferon-alpha (IFN alpha) alone, or combinations of these agents. Half the animals were followed for survival and the other half were sacrificed at the end of the experiment for quantification of tumor burden. The blood of the sacrificed animals was utilized in a series of immunological tests in order to demonstrate the cytolytic potential of the peripheral blood lymphocytes (PBL) in each treatment group, as well as to characterize phenotypically the cells acting as effectors. The triple-adjuvant regimen group was by far the most effective treatment group, demonstrating 100% survival and a significant reduction in tumor burden when compared to other groups. Furthermore, the PBL from the animals in this group showed 69.4% lysis of the CC-36 target cells in vitro. These effector lymphocytes were characterized as ASMG1-/Lyt2.2+ cytolytic lymphocytes. We conclude that these lymphocytes were stimulated by the administration of VCO and further augmented by the immunomodulation of the cytokines given in the triple regimen, and that such a regimen might prove beneficial in the treatment of established hepatic metastases from weakly immunogenic tumors.