T cell responses in colorectal cancer patients: evidence for class II HLA-restricted recognition of shared tumor-associated antigens

Natural killer cells inhibit metastasis of ovarian carcinoma cells and show therapeutic effects in a murine model of ovarian cancer

Ovarian cancer has the highest mortality rate and is the most common of all gynecologic malignancies. Novel treatments for ovarian cancer are urgently required to improve outcomes and the overall survival of patients. The present study investigated whether immunotherapy with natural killer (NK) cells affected the survival of mice with ovarian cancer. Results analysis identified adjunctive NK cells as a potential therapeutic method in ovarian cancer. Patient-derived ovarian cells were isolated, cultured and subsequently injected subcutaneously into immune deficient BALB/c-nude mice. Human NK cells were isolated from peripheral blood mononuclear cells and cultured for expansion in vitro. The present results demonstrated that ovarian cells in BALB/c-nude mice did not induce spontaneous ovarian cancer cell metastasis in the NK-treated group. In addition, NK cells activated immune cells in the immune system, which resulted in inhibition of ovarian tumor growth in vitro and in a murine xenograft model of ovarian cancer. The data also indicated that cytotoxic activity of NK cells prevented migration and invasion of ovarian cancer cells, which contributed to prevention of systemic metastasis and suggested that NK cells could be effective cells for therapy against ovarian cancer. Furthermore, NK cells induced apoptosis and increased the number of cluster of differentiation (CD)4⁺, CD8⁺ as well as cytotoxic T lymphocyte responses by intravenous injection in a murine xenograft model of ovarian cancer. These results suggested that NK cells inhibited the systemic metastasis for ovarian cancer cells. In conclusion, the present study suggested that NK cell immunotherapy inhibited systemic metastasis of ovarian cancer cells and improved the survival rate of mice. Sufficient supplementation of NK cells may serve as a promising immunotherapeutic strategy for ovarian cancer.

In situ cytotoxic and memory T cells predict outcome in patients with early-stage colorectal cancer

PURPOSE

Many patients who present with early-stage colorectal cancer (International Union Against Cancer TNM stages I and II) are nevertheless at high risk of relapse. We hypothesized that intratumoral immune reaction could influence their prognosis.

PATIENTS AND METHODS

The intratumoral immune reaction was investigated in 29 tumors by large-scale real-time polymerase chain reaction. Cytotoxic (CD8) and memory (CD45RO) T cells were quantified by immunohistochemical analyses of tissue microarrays from the center (CT) and the invasive margin (IM) of the 602 tumors from two independent cohorts. The results were correlated with tumor recurrence and patient survival.

RESULTS

Patients with a strong infiltration of CD45RO(+) cells in the tumor exhibited an increased expression of T-helper 1 and cytotoxicity-related genes. Densities of CD45RO(+) and CD8(+) cells in tumor regions (CT/IM) classified the patients into four distinct prognostic groups based on the presence of high density of each marker in each tumor region. The four groups were associated with dramatic differences in disease-free, disease-specific, and overall survival (all P < .0001). Five years after diagnosis, only 4.8% (95% CI, 0.6% to 8.8%) of patients with high densities of CD8(+) plus CD45RO(+) cells had tumor recurrence, and 86.2% (CI, 79.4% to 93.6%) survived. In contrast, the tumor recurred in 75% (95% CI, 17% to 92.5%) of patients with low densities of these cells, and only 27.5% (95% CI, 10.5% to 72%) survived (all P < .0001). Multivariate analyses showed that the immune criteria had independent effects on the rates of complete remission and survival.

CONCLUSION

The combined analysis of CD8(+) plus CD45RO(+) cells in specific tumor regions could provide a useful criterion for the prediction of tumor recurrence and survival in patients with early-stage colorectal cancer.

Fluorescent nanocrystal-encoded microbeads for multiplexed cancer imaging and diagnosis

Bead-based assays on very large numbers of molecules in proteomics, genomics, drug screening and clinical diagnostics require encoding of each of the microbeads according to the particular ligand bound to its surface. The benefits of using optically encoded microbeads (instead of the solid-state two-dimensional arrays) are derived from the freedom of bead to move in three dimensions. Polymeric beads optically encoded with organic dyes allow for a limited number of unique codes whereas the use of semiconductor nanocrystals as fluorescent tags improves the beads multiplexed imaging capabilities, photostability and sensitivity of the antigen detection. Additionally, an employment of the recently demonstrated Förster resonance energy transfer (FRET) from the microbeads nanocrystal codes to the nearby antibody dye label allows for the very specific detection of the interaction between the microbead and the antibody. This interaction turns the fluorescence signal from dye label off and on thus effectively discriminating between the occurrence and the non-occurrence of antibody binding. The absence of fluorescent background from non-interacting with the beads dye-labelled antibodies additionally increases the sensitivity of detection and further facilitates the multiplexing capabilities of nanocrystals-based detection and diagnostics. This paper reviews the state-of-the-art results of development of microbeads optically encoded with the fluorescent nanocrystals "quantum dots" and their applications to proteomics for cancer antigens and autoantibodies imaging and diagnosis.

The essential role of the in situ immune reaction in human colorectal cancer

Colorectal cancer is the second most common cause of cancer-related death. Novel prognostic factors should be identified and validated to refine the present tumor-node-metastasis system. The presence of immune cells infiltrating colorectal cancers is a common phenomenon. However, the current belief is that clinically detectable human tumors escaping immune surveillance are no longer kept in check by the immune cells of the tumor microenvironment. Despite studies showing the influence of immune cell infiltrates on the behavior of colorectal carcinomas, this parameter is not currently recognized as a reliable prognostic factor. We showed that the nature, functional orientation, density, and location of immune cells within distinct tumor regions could provide a prognostic factor superior to and independent of criteria related to the anatomic extent of the tumor. The strength of the immune reaction identified in our studies could advance our understanding of cancer evolution and have important consequences for clinical practice.

A novel murine model of allogeneic vaccination against prostate cancer

Prostate cancer continues to be a major cause of death in men. Surgical and medical treatments of the disease have improved, but metastasic disease remains a significant clinical problem. Novel therapies such as whole cell vaccination offer the potential of treating disease by stimulating the immune system. To study the efficacy of a whole cell vaccine in prostate cancer two strains of mice were used: C57BL/6 (H-2Kb) and C3H/HeJ (H-2K(k)) in combination with four different cell lines. Thus, a model was constructed of allogeneic and syngeneic vaccine, as well as a challenge tumour for each strain. Two novel cell lines were developed during this study. Firstly, the non tumourigeneic PMC-1 was derived from a normal mouse prostate and immortalized with HPV16. Secondly, the tumourigeneic PMC-1 C6ras1p1 was transformed with human ras gene which formed tumours in both SCID and C3H/HeJ mice. Protection, and the nature of the immune response to syngeneic and allogeneic vaccine, in males and females was examined in both strains. Vaccination with both syngeneic and allogeneic irradiated whole cell vaccines induced protection from syngeneic challenge in females. However, no protection was observed when allogeneic vaccine was given to male mice. This correlated with the immune response. Two types of cellular immune responses were generated in females. A NK-mediated response was observed in C57BL/6 mice, whilst C3H/HeJ mice developed a CTL response. Little or no cellular immune response was observed in males. The cytokine profile in C3H/HeJ females was a mixture of Th1 and Th2 whilst a mainly Th1 profile was observed in C57BL/6 mice. Male mice showed a diminished cytokine secretion compared to females which was further depressed after challenge. The difference in immunity was largely as expected, since tolerance to prostate antigens should not normally develop in female mice. However, this makes this model particularly relevant clinically since it directly mimics the human situation and thus may accelerate the development of whole cell vaccines for clinical use.

Late dendritic cells are still able to evoke a potent alloreactive CTL response

On exposure to maturation stimuli, immature dendritic cells (DCs) undergo changes that turn them into potent amplifiers of innate immunity and into antigen-presenting cells (APCs) able to prime naïve T cells. However, their progression through the maturation process is very rapid and finally ends in apoptosis. The aim of our study was to investigate the importance of the maturation stage of DCs, defined by morphology, expression of surface markers and IL-12 production, for their immunostimulatory capacity. DCs were matured with LPS, monocyte-conditioned medium (MCM) or TNF-alpha, sampled several times during a 3-day long maturation period and used as stimulators of allogeneic T cells over a wide range of DC/T cell ratios. T-cell response was assessed by cell proliferation, CTL generation and IFN-gamma production. Our results indicate that the in vitro T cell response is determined mainly by the level of expression of co-stimulatory molecules on DCs and the DC/T cell ratio in the culture. Thus, DCs matured for over 20h, with high expression of co-stimulatory molecules, can still induce a potent CTL response at DC/T cell ratios of 1:10 and 1:20, although their IL-12 production, as well as their ability to induce IFN-gamma production by T cells, are both decreased. In contrast, the CTL response at DC/T cell ratios of 1:2 and 1:5 can be profoundly decreased. Notably, the proportion of proliferating CD4+ T cells in these cultures is reduced. This could well be the reason for the absence of CTL response, since we showed that, even in the case of high expression of co-stimulatory molecules on DCs, generation of CTLs still depends on CD4+ T cells. Our study emphasizes the importance of strong expression of co-stimulatory molecules on DCs and of their ability to activate CD8+ and CD4+ T cells concomitantly in order to initiate a potent cell-mediated immune response. We therefore suggest that a combination of early DCs, which are strong producers of cytokines, and late DCs, which have high expression of co-stimulatory molecules, could prove beneficial in the attempt to initiate in vitro and in vivo cell-mediated immune responses for therapeutic purposes.

Shared immunoproteome for ovarian cancer diagnostics and immunotherapy: potential theranostic approach to cancer

Elimination of cancer through early detection and treatment is the ultimate goal of cancer research and is especially critical for ovarian and other forms of cancer typically diagnosed at very late stages that have very poor response rates. Proteomics has opened new avenues for the discovery of diagnostic and therapeutic targets. Immunoproteomics, which defines the subset of proteins involved in the immune response, holds considerable promise for providing a better understanding of the early-stage immune response to cancer as well as important insights into antigens that may be suitable for immunotherapy. Early administration of immunotherapeutic vaccines can potentially have profound effects on prevention of metastasis and may potentially cure through efficient and complete tumor elimination. We developed a mass-spectrometry-based method to identify novel autoantibody-based serum biomarkers for the early diagnosis of ovarian cancer that uses native tumor-associated proteins immunoprecipitated by autoantibodies from sera obtained from cancer patients and from cancer-free controls to identify autoantibody signatures that occur at high frequency only in cancer patient sera. Interestingly, we identified a subset of more than 50 autoantigens that were also processed and presented by MHC class I molecules on the surfaces of ovarian cancer cells and thus were common to the two immunological processes of humoral and cell-mediated immunity. These shared autoantigens were highly representative of families of proteins with roles in key processes in carcinogenesis and metastasis, such as cell cycle regulation, cell proliferation, apoptosis, tumor suppression, and cell adhesion. Autoantibodies appearing at the early stages of cancer suggest that this detectable immune response to the developing tumor can be exploited as early-stage biomarkers for the development of ovarian cancer diagnostics. Correspondingly, because the T-cell immune response depends on MHC class I processing and presentation of peptides, proteins that go through this pathway are potential candidates for the development of immunotherapeutics designed to activate a T-cell immune response to cancer. To the best of our knowledge, this is the first comprehensive study that identifies and categorizes proteins that are involved in both humoral and cell-mediated immunity against ovarian cancer, and it may have broad implications for the discovery and selection of theranostic molecular targets for cancer therapeutics and diagnostics in general.

Tissue expression and sero-reactivity of tumor-specific antigens in colorectal cancer

The expression of 14 individual and two groups of tumor antigens was characterized for colorectal carcinoma by RT-PCR using 26 colorectal carcinoma specimens, eight cell lines, six samples of patients with inflammatory bowl diseases, and nine specimens from different locations of an individual patient with a metastasized rectal carcinoma. The most frequently detected mRNAs were MAGE-A1 (58%), GAGE-3-7 (54%), and cTAGE-5a (31%). At medium frequencies (12-19%) we found cTAGE-1, MAGE-A2, se57-1, RAGE-4, and GAGE-1,2,8, while other tumor antigens were expressed rarely (<9%). 85% of the samples were positive for at least one of the most frequently expressed antigens. Using a secondary SEREX approach and sera of eight colorectal cancer patients we found reactive antibodies against recombinant cTAGE-1 (2 sera), se57-1 (2), truncated GAGE (1), and MAGE-A1 (1). We conclude that certain cancer-germline genes can be detected in colorectal cancer and might therefore be promising targets for immunotherapy.

Effect of Dose on Immune Response in Patients Vaccinated With an HER-2/neu Intracellular Domain Protein—Based Vaccine

Purpose

To evaluate the safety of an HER-2/neu intracellular domain (ICD) protein vaccine and to estimate whether vaccine dose impacts immunogenicity.

Patients and Methods

Twenty-nine patients with HER-2/neu—overexpressing breast or ovarian cancer and with no evidence of disease after standard therapy received a low- (25 μg), intermediate- (150 μg), or high-dose (900 μg) HER-2/neu ICD protein vaccine. The vaccine was administered intradermally, monthly for 6 months, with granulocyte-macrophage colony-stimulating factor as an adjuvant. Toxicity and both cellular and humoral HER-2/neu—specific immunity was evaluated.

Results

The vaccine was well tolerated. The majority of patients (89%) developed HER-2/neu ICD-specific T-cell immunity. The dose of vaccine did not predict the magnitude of the T-cell response. The majority of patients (82%) also developed HER-2/neu—specific immunoglobulin G antibody immunity. Vaccine dose did not predict magnitude or avidity of the HER-2/neu—specific humoral immune response. Time to development of detectable HER-2/neu—specific immunity, however, was significantly earlier for the high- versus low-dose vaccine group (P = .003). Over half the patients retained HER-2/neu—specific T-cell immunity 9 to 12 months after immunizations had ended.

Conclusion

The HER-2/neu ICD protein vaccine was well tolerated and effective in eliciting HER-2/neu—specific T-cell and antibody immunity in the majority of breast and ovarian cancer patients who completed the vaccine regimen. Although the dose of vaccine did not impact the magnitude of T-cell or antibody immunity elicited, patients receiving the highest dose developed HER-2/neu—specific immunity more rapidly than those who received the lowest dose.

Immunology and immunotherapy of colorectal cancer

This review critically discusses data on immunology of colorectal cancer, starting from pathology and molecular biology, and then considering the molecular characterisation of colon cancer antigens and the clinical trials of immunotherapy. A careful evaluation of histopathological studies on intra-epithelial infiltration by T cells in primary tumours, together with the analysis of HLA expression by colorectal cancer cells, suggest that anti-tumour T cell immune responses may take place in vivo in those patients, influencing prognosis and shaping the tumour immunological profile. Moreover, the molecular characterisation of tumour antigens expressed by colorectal carcinomas, together with improved understanding of mechanisms of the immune response and more sensitive methods for the in vivo detection of T cell responses, are now allowing researchers to design new and more effective vaccination protocols, with encouraging preliminary results. By drawing together the experimental evidence from different research fields, this review provides support for the concept that colorectal carcinoma is immunogenic and may reasonably be considered as a target for immunotherapy, and attempts to address critical issues and envisage future developments in this challenging research field.

Current methods for loading dendritic cells with tumor antigen for the induction of antitumor immunity

The immunotherapy of cancer is predicated on the belief that it is possible to generate a clinically meaningful antitumor response that provides patient benefit, such as improvement in the time to progression or survival. Indeed, immunotherapeutics with dendritic cells (DC) as antigen-presenting delivery vehicles for cell-based vaccines have already improved patient outcome against a wide range of tumor types (1-9). This approach stimulates the patient's own antitumor immunity through the induction or enhancement of T-cell immunity. It is generally believed that the activity of cytotoxic T lymphocytes (CTL), the cells directly responsible for killing the tumor cells in vivo, are directed by DC. Therefore, the goal of many current designs for DC-based vaccines is to induce strong tumor-specific CTL responses in patients with cancer. In practice, most studies for DC-based cancer vaccine development have focused on the development of methods that can effectively deliver exogenous tumor antigens to DC for cross-priming of CD8+ T cells through the endogenous MHC class I processing and presentation pathway (10). To date, many methods have been developed or evaluated for the delivery of defined and undefined tumor antigens to DC. This review provides a brief summary on these methods, the techniques used in these methods, as well as the advantages and disadvantages of each method.

The prognostic value of invariant chain (Ii) and Her-2/neu expression in curatively resected colorectal cancer

BACKGROUND

Current methods to predict outcome for patients with curatively resected colorectal cancer are not ideal. The combined use of molecular markers and clinicopathologic features may better identify patients who are at risk for recurrence. The Her-2/neu and invariant chain molecules may be important in cancer development and progression, but their usefulness as clinical predictors of outcome in colorectal cancer has not been well studied.

METHODS

We used immunohistochemistry to determine the expression of Her-2/neu, invariant chain, p27, and p53 in primary tumor samples from 156 patients with curatively resected stage I-III colorectal cancer. The association between expression and clinical outcomes was assessed by univariate and multivariate analysis.

RESULTS

Her-2/neu expression was detected in only 24% of cases, and high levels of invariant chain were detected in only 15%. Although patients whose tumors overexpressed Her-2/neu survived longer than those with non-overexpressing tumors, neither Her-2/neu nor invariant chain were independently associated with survival. Consistent with previous reports, high p27 expression was associated with improved outcome, whereas overexpression of p53 was associated with worse outcome.

CONCLUSIONS

Our study did not reveal a statistically significant association between Her-2/neu or invariant chain expression and clinical outcomes in patients with curatively resected colorectal cancer. However, the data suggest that Her-2/neu could be a favorable prognostic variable. Because of the low frequency of Her-2/neu expression, larger numbers of patients need to be studied for this question to be adequately answered.