Immunotherapy for colorectal cancer

Immunotherapeutic effects of recombinant colorectal cancer antigen produced in tomato fruits

The production of pharmacological vaccines in plants has been an important goal in the field of plant biotechnology. GA733-2, the protein that is also known as colorectal carcinoma (CRC)-associated antigen, is a strong candidate to produce a colorectal cancer vaccine. Tomato is the one of the major targets for production of an edible vaccine, as tomato is a fruit consumed in fresh form. It also contains high content of vitamins that aid activation of immune response. In order to develop an edible colorectal cancer vaccine, the transgene rGA733-Fc that encodes a fusion protein of GA733-2, the fragment crystallizable (Fc) domain, and the ER retention motif (rGA733-Fc) was introduced into tomato plants (Solanumlycopersicum cv. Micro-Tom). The transgenic plants producing rGA733-Fc (rGA733-Fc^OX) protein were screened based on stable integration of transgene expression cassette and expression level of rGA733-Fc protein. Further glycosylation pattern analysis revealed that plant derived rGA733-Fc protein contains an oligomannose glycan structure, which is a typical glycosylation pattern found on ER-processing proteins. The red fruits of rGA733-Fc^OX transgenic tomato plants containing approximately 270 ng/g FW of rGA733-Fc protein were orally administered to C57BL/6 mice. Oral administration of tomato fruits of the rGA733-Fc expressing transgenic plants delayed colorectal cancer growth and stimulated immune responses compared to oral administration of tomato fruits of the h-Fc expressing transgenic plants in the C57BL/6J mice. This is the first study showing the possibility of producing an edible colorectal cancer vaccine using tomato plants. This research would be helpful for development of plant-derived cancer edible vaccines.

Vaccination with Viable Human Umbilical Vein Endothelial Cells Prevents Metastatic Tumors by Attack on Tumor Vasculature with Both Cellular and Humoral Immunity

PURPOSE

Because tumor endothelium is rarely targeted by immunity but is critically important for tumor growth, the immunity against tumor endothelium is to be developed as a novel antitumor strategy.

EXPERIMENTAL DESIGN

First, viable human umbilical vein endothelial cells (HUVEC) were immunized to C57BL/6 and BALB/c mice to evoke specific CTLs as well as antibodies against tumor endothelium. Lewis lung carcinoma or myeloma cells were subsequently inoculated to evaluate the effect on tumor growth by vaccination. Second, the effect on tumor metastasis by vaccination was studied using tumor-resected mice receiving HUVEC immunization 3 days after excision. Third, the immune sera and T lymphocytes from HUVEC-immunized mice were transferred to tumor-bearing mice and added to cultured HUVECs to investigate their antiproliferative effect.

RESULTS

Viable HUVEC immunization showed potent antitumor effects in Lewis lung carcinoma and myeloma tumor models. Both immune sera and CTL inhibited tumor growth and specifically suppressed proliferation of HUVECs. Particularly, tumors entirely disappeared on day 90 after tumor inoculation in four of six tumor-bearing mice receiving CTL therapy. In a metastatic tumor model, we found that the HUVEC vaccination prolonged life span from 30.9 to 41.5 days after tumor resection compared with PBS-treated mice without apparent side effects.

CONCLUSIONS

Vaccination with viable HUVECs evoked both humoral and cellular immunity against tumor microvasculature, and therefore significantly inhibited tumor growth and prolonged life span of tumor-resected mice. This may provide with a novel treatment for metastatic tumors. Moreover, we have established a convenient method to evoke specific CTL against tumor angiogenesis.

Active specific immunotherapy in colon cancer

Colorectal cancer is one of the leading causes of cancer-related mortality. After a series of clinical trials, the adjuvant 5-FU-based chemotherapy has established a definitive role in the management of stage III colon cancer. While the precise role for chemotherapy in stage II disease remains under investigation, less toxic treatment modalities such as active specific immunotherapy (ASI) have emerged as potentially attractive alternatives. In a randomized trial it was demonstrated that ASI, using autologous tumor cells and BCG, had a significant clinical benefit in the adjuvant treatment of stage II colon cancer. In addition, it was found that the delayed-type cutaneous hypersensitivity reactions (DTH) against autologous cells correlated significantly with survival, confirming its suitability for immunomonitoring. Nowadays, 5-FU-based chemotherapy is a standard treatment for stage III colon cancer and because there is preclinical evidence for synergism between chemotherapy and ASI, we performed a phase II study to investigate whether the combined treatment with 5-FU and ASI is tolerable and feasible. We demonstrated that 5-FU treatment hardly affected the DTH response against autologous tumor cells and that the combination treatment was well tolerated. A randomized phase III trial is now warranted to show that the combination of ASI and chemotherapy is superior to chemotherapy alone.

Immunization with a plant-produced colorectal cancer antigen

Cancer vaccination has become an important focus of oncology in recent years. Active immunization with tumor-associated antigens such as colorectal cancer antigen GA733-2 is thought to potentially overcome the reoccurrence of metastasis. As recombinant protein production in bioreactors is costly and subject to growing safety concerns, we tested plants as an alternative for the expression of a potential colorectal cancer vaccine. Comparing colorectal cancer antigen GA733-2 produced in tobacco plants with the same antigen produced in insect cell culture, we found a similar humoral immune response to injection of either of the two antigen preparations into mice. Some minor differences were observed in the cellular response that might be due to impurities. Our studies compare for the first time, immunization with the same antigen expressed in either plants or insect cell culture. This will provide important data for use of plants as production systems of therapeutics.

Vaccination with autologous endothelium inhibits angiogenesis and metastasis of colon cancer through autoimmunity

Overcoming immune tolerance of tumor angiogenesis should be useful for adjuvant therapy of cancer. We hypothesized that vaccination with autologous endothelium would induce an autoimmune response targeting tumor angiogenesis. To test this concept, we immunized BALB/c mice with a vaccine of glutaraldehyde-fixed murine hepatic sinusoidal endothelial cells (HSEs) in a lung metastasis model of Colon-26 cancer. Vaccination with autologous HSEs induced both preventive and therapeutic anti-tumor immunity that significantly inhibited the development of metastases. ELISA revealed an immunoglobulin response involving IgM and IgG subclasses. These antibodies had a strong affinity for antigens of both murine and human endothelium, and lyzed endothelial cells in the CDC assay. Flow-cytometry and chromium-release cytotoxicity assay revealed a specific CTL response against endothelial cells, which were lyzed in an effector: target ratio-dependent manner. Neither antibodies nor CTLs reacted with Colon-26. The effect of autologous HSEs was more pronounced than that of xenogeneic human umbilical vein endothelial cells (HUVECs), which were tested in the same experimental setting. Our results suggest that vaccination with autologous endothelium can overcome peripheral tolerance of self-angiogenic antigens and therefore should be useful for adjuvant immunotherapy of cancer.

Influence of drug-induced apoptotic death on processing and presentation of tumor antigens by dendritic cells

Here we have studied the effects of apoptotic cell death induced by chemotherapic agents on tumor phagocytosis by dendritic cells (DC) and presentation of the relevant antigen to T lymphocytes. Annexin-V-FITC (Ann-V) and propidium iodide (PI) staining was used to assess early apoptotic (Ann-V(+)/PI(-)) vs. late apoptotic/secondary necrotic (Ann-V(+)/PI(+)) death after a 24 hr observation of untreated and drug-treated gastric carcinoma cells. After treatments, the HLA-A*0201(+) tumor cell line KATO III was exposed for 24 hr to allogeneic, HLA-related GM-CSF, IL-4-driven immature (i) DC. Tumor-loaded iDC were tested for IL-12 release in an ELISA assay, incubated with the DC-maturating factor TNF-alpha and used as stimulators for autologous T lymphocytes. Generation of antitumor T response against KATO cells was evaluated in an anti-MHC class I MAb-blocked Interferon-gamma ELISPOT assay. After treatment with Cis-platin (cis), all dying cells were in early apoptosis, whereas secondary necrosis was the prevalent death pattern observed after epirubicin (epi) and doxorubicin (doxo). Doxo and epi increased tumor expression of heat shock protein (hsp) 70 and uptake of tumor cell components by DC, whereas cis treatment had no effect on hsp70 and was associated with poor tumor uptake by DC. Significant upmodulation of IL-12 was observed by DC that had taken up the doxo- and epi-treated tumors (p< 0.005 and p< 0.01, respectively). Increased IFN-gamma release was also observed after stimulation of T lymphocytes with DC loaded with doxo- and epi-treated (p< 0.02 and p< 0.005, respectively) but not with cis-treated DC. These data show that the products of early apoptosis cannot efficiently cross-activate MHC class I-restricted anti-tumor lymphocytes even in the presence of DC maturating factors, whereas secondary necrosis is associated with robust T cell response.

Application of autologous tumor cell vaccine and NDV vaccine in treatment of tumors of digestive traet

AIM: To treat patients with stage I-IV malignant tumors of digestive tract using autologous tumor cell vaccine and NDV (Newcastle disease virus) vaccine, and observe the survival period and curative effect.

METHODS: 335 patients with malignant tumors of digestive tract were treated with autologous tumor cell vaccine and NDV vaccine. The autologous tumor cell vaccine received were assigned for long-term survival observation. While these failed to obtain the autologous tumor tissue were given with NDV vaccine for a received short-term observation on curative effect.

RESULTS: The colorectal cancer patients treated with autologous tumor cell vaccine were divided into two groups: the controlled group (subjected to resection alone) (n = 257), the vaccine group (subjected to both resection and immunotherapy) (n = 310). 25 patients treated with NDV immunotherapy were all at stage IV without having resection. In postoperation adjuvant therapy patients, the 5, 6 and 7-year survival rates were 66.51%, 60.52%, 56.50% respectively; whereas in patients with resection alone, only 45.57%, 44.76% and 43.42% respectively. The average survival period was 5.13 years (resection alone group 4.15 years), the median survival period was over 7 years (resection alone group 4.46 years). There were significant differences between the two groups. The patients treated with resection plus vaccine were measured delayed-type hypersensitivity (DTH) reactions after vaccination, (indurative scope > 5 mm). The magnitude of DTH was related to the prognosis. The 5-year survival rate was 80% for those with indurations greater than 5 mm, compared with 30% for those with indurations less than 5 mm. The 1-year survival rate was 96% for 25 patients treated with NDV immunotherapy. The total effective rate (CR+PR) was 24.00% in NDV immunotherapy; complete remission (CR) in 1 case (4.00%), partial remission (PR) in 5 cases (20.00%), stabilizedin in 16 cases (64.00%), progression (PD) in 1 case (4.00%). After NDV vaccine immunotherapy, the number of NK cell increased and immune function imporved obviously.

CONCLUSION: The autologous tumor cell vaccine and NDV vaccine can prolong the patients’ life. NDV vaccine is notably effective for short-term with promotion of quality of life and can be used whenever necessary with good prospects.

Local administration of IL-12-transfected dendritic cells induces antitumor immune responses to colon adenocarcinoma in the liver in mice

Colorectal cancer is one of the most common fatal malignancies in the United States, with an incidence second only to lung cancer. The liver is the most common site of colorectal metastases and frequently the only affected organ once the primary tumor has been surgically removed. The only potentially curative treatment for metastatic colorectal cancer in the liver is surgery, although most patients are not eligible for resection. We have therefore, evaluated the therapeutic efficacy of dendritic cells (DCs) engineered to express IL-12 in a liver metastasis model. Direct administration of DCs into the portal vein significantly inhibited the growth of established MC38 colon carcinoma in the liver in C57BL/6 mice. This effect was accompanied by an intratumoral accumulation of CD4+, CD8+, and NLDC-145+ immune effector cells, and also resulted in a systemic immune response as determined by enhanced production of IFN-gamma by T lymphocytes isolated from both spleen and draining lymph nodes. Evaluation of homing of Cy3-labeled DCs following the portal vein injection confirmed their distribution in the liver and lymphoid tissue. Thus, a local delivery of DCs transduced with the IL-12 gene can not only inhibit colorectal tumor growth in vivo but also mount systemic antitumor immune responses. This approach is likely to improve the outcome of immunotherapy for metastatic colorectal cancer since high numbers of tumor-associated DCs positively correlate with a more favorable prognosis. Simultaneous local gene therapy with IL-12 will further improve clinical efficacy without placing the patient at risk for systemic toxicity.

Introduction to colorectal cancer

OBJECTIVES

To provide an overview of colorectal carcinoma (CRC), including current treatment strategies for various stages of the disease.

DATA SOURCES

Research articles and textbooks.

CONCLUSIONS

Despite screening methods for early detection of CRC, many patients present with late-stage disease and have a poor prognosis. The approval of irinotecan for CRC changed the approach to treatment, and there are numerous agents under clinical evaluation that may soon be available for the management of patients with CRC.

IMPLICATIONS FOR NURSING PRACTICE

Recent advances in molecular targeting have led to the development of new treatments for CRC. Because nurses will ultimately administer these agents, it is important to understand how these agents target CRC.