Adjuvant active specific immunotherapy for stage II and III colon cancer with an autologous tumor cell vaccine: Eastern Cooperative Oncology Group Study E5283

Harnessing the immune system for ovarian cancer therapy

The clinical course of ovarian cancer is often marked by periods of relapse and remission until chemo-resistance develops. Patients in remission with minimal disease burdens are ideally suited for the evaluation of immune-based strategies. Major obstacles to the development of successful immune strategies include the identification of tumor-restricted immunogenic targets, generation of a sufficient immune response to cause tumor rejection, and approaches to overcome evasion of immune attack. Many questions remain as optimal strategies are developed, which include: (i) What is the best antigen form (e.g. peptides, proteins or tumor lysates)? (ii) What are the appropriate adjuvants? (iii) Are mono-valent or multi-valent vaccines likely to be more effective? (iv) What is the optimal frequency and duration of vaccination? (v) How should antigen-specific responses be monitored? and (vi) How should the anti-cancer response be maintained? In this review, we explore representative examples of immune strategies under investigation for patients with ovarian carcinoma which illustrate many of these issues. Basic principles generic to all these immunotherapeutic approaches will also be discussed.

Cell based cancer vaccines: regulatory and commercial development

There is both clinical and regulatory drive to expedite development of safe, efficacious cancer therapies. Stimulation of the patients immune system through vaccination with tumour cells has long been at the vanguard of cancer therapeutic vaccines, and several have been demonstrated to be safe and to have efficacy in early clinical trials for a range of cancers including melanoma, renal cell carcinoma, prostate and colorectal cancers. A number of development-stage vaccines and strategies are currently being tested, utilising either autologous or allogeneic tumour cells, which may also have been ex vivo manipulated (e.g. cytokine transfected cells). It seems likely that clinical trial success, and hence patient benefit, could be improved through better patient identification, possibly by the discovery and use of novel immune response biomarkers. In this review, we aim to summarise the state of tumour cell vaccines in commercial development and to explore not only the difficulties of determining efficacy, but also the production challenges faced when developing a vaccine from proof of principle to pivotal phase III trials.

A phase II prospective multi-institutional trial of adjuvant active specific immunotherapy following curative resection of colorectal cancer hepatic metastases: cancer and leukemia group B study 89903

BACKGROUND

Patients with curatively resected colorectal cancer hepatic metastases often harbor occult metastatic disease and are at high risk of experiencing recurrence. This patient cohort is ideally suited to test novel therapies such as immunotherapy. We treated patients-post-hepatic resection-with anti-idiotype monoclonal antibody vaccines to the tumor-associated antigens carcinoembryonic antigen (CeaVac) and human milk fat globule (TriAb), both of which are co-expressed in more than 90% of colorectal cancer patients.

METHODS

Vaccinations commenced 6-12 weeks post-hepatic resection and consisted of four biweekly treatments of 2 mg CeaVac and TriAb, then monthly treatments for 2 years, then on every other month for 3 years. The primary endpoint was to investigate the proportion of patients recurrence-free at 2 years, and the objective of the study was to demonstrate that at least 58% would be recurrence-free at this time to consider the regimen worthy of further study.

RESULTS

Between July 2001 and October 2004, 56 patients were accrued; 52 patients with margin-negative resection were eligible for analysis. Hepatic lobectomy was performed in 56% of patients with a median of one metastasis (range 1-3). Of the 52 eligible patients, 49 were evaluable for the primary end point. Median follow-up was 3.1 years. The proportion of patients recurrence-free at 2 years was 39%, with a lower confidence bound (LCB) of 0.29. Median recurrence-free survival was 16 months. The 2-year overall survival was 94% (95% CI, 0.81, 0.98). Only 10% of patients had documented grade-3 adverse events.

CONCLUSIONS

Anti-idiotype monoclonal antibody vaccine therapy with CeaVac and TriAb as an adjuvant to curative resection of colorectal cancer hepatic metastases is well tolerated but did not improve 2-year recurrence-free survival when compared with the expected value of 40% reported for hepatic resection alone.

Cancer vaccines: a promising cancer therapy against all odds

Vaccination as an approach to control cancer growth and recurrence, also known as active-specific immunotherapy (ASI), has been successful at inducing immune responses, even in patients with advanced or metastatic disease. Clinical responses, as determined by the criteria set for chemotherapy and radiation, have been much more difficult to assess. In general, the effectiveness of ASI in advanced disease is expected to be limited. The lack of toxicity in thousands of vaccinated patients with many different tumor types, and clearly observed, albeit rare, efficacy, support the use of ASI in early disease following resection of the primary tumor or removal of precancerous lesions. This setting will permit a much more rational assessment of the long-term efficacy of ASI, as well as its toxicity. Given that ASI relies on a healthy immune system to be effective, it is also predicted to be more successful when it is employed prior to the use of standard chemotherapy. At the very least, it should be given primary consideration in situations where the role of cytotoxic chemotherapy is equivocal and patients are in need of a nontoxic alternative.

Immunologic approaches to ovarian cancer treatment

The clinical course of ovarian cancer is often marked by periods of relapse and remission until chemotherapy resistance develops. Patients in remission with minimal disease burdens are ideally suited for the evaluation of immune-based strategies. The role of immune surveillance in improving outcome has been supported by the correlation of increased survival with the presence or absence of tumor-infiltrating lymphocytes in a given patient. Major obstacles to the development of successful immune strategies include the identification of tumor-restricted immunogenic targets, generation of a sufficient immune response to cause tumor rejection, and approaches to overcome evasion of immune attack. As optimal strategies are being developed, many questions remain. Some of the questions are as follows: What is the best antigen form (eg, peptides, proteins, or tumor lysates)? What are the appropriate adjuvants? Are monovalent or multivalent vaccines likely to be more effective? What is the optimal frequency and duration of vaccination? How should antigen-specific responses be monitored? How should the anticancer response be maintained? In this review, we will explore representative examples of immune strategies under investigation for patients with ovarian carcinoma that illustrate many of these issues. We will review ongoing phase III studies for patients in first clinical remission. Basic principles generic to all these immunotherapeutic approaches will be discussed in the hopes of yielding the most promising results as the field continues to evolve.

Endpoints in Adjuvant Treatment Trials: A Systematic Review of the Literature in Colon Cancer and Proposed Definitions for Future Trials

Disease-free survival is increasingly being used as the primary endpoint of most trials testing adjuvant treatments in cancer. Other frequently used endpoints include overall survival, recurrence-free survival, and time to recurrence. These endpoints are often defined differently in different trials in the same type of cancer, leading to a lack of comparability among trials. In this Commentary, we used adjuvant studies in colon cancer as a model to address this issue. In a systematic review of the literature, we identified 52 studies of adjuvant treatment in colon cancer published in 1997-2006 that used eight other endpoints in addition to overall survival. Both the definition of these endpoints and the starting point for measuring time to the events that constituted these endpoints varied widely. A panel of experts on clinical research on colorectal cancer then reached consensus on the definition of each endpoint. Disease-free survival--defined as the time from randomization to any event, irrespective of cause--was considered to be the most informative endpoint for assessing the effect of treatment and therefore the most relevant to clinical practice. The proposed guidelines may add to the quality and cross-comparability of future studies of adjuvant treatments for cancer.

Evaluation of particulate systems supporting tumor cell fractions in a preventive vaccination against intracranial rat glioma

Object

Irradiated autologous tumor cells are commonly used as a source of antigens in antiglioma vaccinations to activate the immune system. As cell number is often a limiting factor in these cells’ preparation, the aim of the present study was to find a means that can lower the amount of cells required. Among strategies currently developed, adjuvant particulate systems offer a promising means to improve the antitumor immune response. In this study, the authors were interested in evaluating the role of particulate systems containing biodegradable microspheres that carry tumor cell fractions on their surfaces in the induction of a protective immunity in the 9L/Fischer 344 rat glioma model. The efficiency of these particulate systems was compared to that of irradiated 9L cells.

Methods

Particulate systems composed of poly(d,l-lactide-co-glycolide) (PLGA) microspheres that support 9L cell fractions on their surfaces (cell lysates or plasma membranes) or irradiated 9L cells alone were injected subcutaneously into the flanks of syngeneic Fischer 344 rats. Eighteen days later, the rats were intracranially injected with nonirradiated 9L cells. A study of survival in these animals and an analysis of the resulting immune response were then conducted.

For the same amount of protein (50 μg) injected, irradiated 9L cells provided long-term survival in 30% of animals, whereas 9L plasma membranes adsorbed onto PLGA microspheres provided long-term survival in 10% of animals and cell lysates adsorbed onto microspheres provided long-term survival in 0%. Accordingly, particulate systems induced a lower T helper cell Type 1 (Th1) peripheral immune response than irradiated 9L cells. However, greater secretion of Th1 cytokines was observed when particulate systems were used than when cell fractions separated from microspheres were used, indicating the adjuvant property of these particulate systems.

Conclusions

Particulate systems have adjuvant properties but are still less efficient than irradiated whole tumor cells for vaccinations. Encapsulation of an activating molecule in the microsphere will be the next developmental step in the search for efficient antiglioma vaccinations.

Review article: immune suppression and colorectal cancer

BACKGROUND

Advances in immunology and molecular biology have shown that colorectal cancer is potentially immunogenic and that host immune responses influence survival. However, immune surveillance and activation is frequently ineffective in preventing and/or controlling tumour growth.

AIM

To discuss potential ways in which colorectal cancer induces immune suppression, its effect upon prognosis and avenues for therapeutic development.

METHOD

A literature review was undertaken for evidence of colorectal cancer-induced immune suppression using PubMed and Medline searches. Further studies were identified from the reference lists of identified papers.

RESULTS

Immune suppression occurs at a molecular and cellular level and can result in a shift from cellular to humoral immunity. Several mechanisms for immune suppression have been described affecting innate and adaptive immunity with suppression linked to poorer clinical outcome.

CONCLUSIONS

Colorectal cancer causes direct inhibition of the host's immune response with a detrimental effect upon prognosis. Immunotherapy offers a therapeutic strategy to counteract these effects with promising results seen particularly in precancerous conditions and early tumours. This review strongly suggests that immunotherapy should be incorporated into adjuvant therapeutic trials for stage 2 tumours and be considered as adjuvant treatment in conjunction with standard chemotherapy regimes for advanced disease.

Locoregional therapy of breast cancer: maximizing control, minimizing morbidity

The goal of locoregional therapy in breast cancer has remained unchanged for a century: the eradication of all malignant cells from the breast and draining lymph nodes, hopefully prior to them having spread to distant organs. However, how we accomplish this goal has changed dramatically over this time period and our success in achieving this goal has been greatly enhanced by improvements in breast imaging and systemic therapies. The therapeutic importance of surgery and radiation has been underestimated in recent years and is thought to have minimal impact on long-term outcome. More recent data have reputed this contention and the relationship between local control and survival in breast cancer is becoming increasingly apparent. This article will review the importance of attaining optimum local control with minimum morbidity and examine where the future of locoregional therapy of breast cancer may lie.

Vaccination therapy in malignant disease

Improvement in survival among patients with early malignancy is well established in various cancers. However, long-term survival in those with advanced malignancy has changed little and this poses a major therapeutic challenge to clinicians. Anti-cancer immunotherapy is a novel approach, which is still experimental, but offers a new therapeutic strategy. In this review, we discuss the basic immunological interplay between the host immune system and the tumour, mechanisms of anti-tumour immune responses induced by immunotherapy and key in vivo pilot studies of active specific immunotherapy in various sold cancers, carried out during the last five years.

Clinical results of vaccine therapy for cancer: learning from history for improving the future

Active, specific immunotherapy for cancer holds the potential of providing an approach for treating cancers, which have not been controlled by conventional therapy, with very little or no associated toxicity. Despite advances in the understanding of the immunological basis of cancer vaccine therapy as well as technological progress, clinical effectiveness of this therapy has often been frustratingly unpredictable. Hundreds of preclinical and clinical studies have been performed addressing issues related to the generation of a therapeutic immune response against tumors and exploring a diverse array of antigens, immunological adjuvants, and delivery systems for vaccinating patients against cancer. In this chapter, we have summarized a number of clinical trials performed in various cancers with focus on the clinical outcome of vaccination therapy. We have also attempted to draw objective inferences from the published data that may influence the clinical effectiveness of vaccination approaches against cancer. Collectively the data indicate that vaccine therapy is safe, and no significant autoimmune reactions are observed even on long term follow-up. The design of clinical trials have not yet been optimized, but meaningful clinical effects have been seen in B-cell malignancies, lung, prostate, colorectal cancer, and melanoma. It is also obvious that patients with limited disease or in the adjuvant settings have benefited most from this targeted therapy approach. It is imperative that future studies focus on exploring the relationship between immune and clinical responses to establish whether immune monitoring could be a reliable surrogate marker for evaluating the clinical efficacy of cancer vaccines.

Peptide-based vaccination for colorectal cancer

Recently, the number of patients with colorectal cancer has been increasing. Although most patients with early colorectal cancer have a good prognosis, in the case of recurrent or metastatic disease, the prognosis is poor and most patients will ultimately die of cancer. Furthermore, the conventional treatment, such as chemotherapy or radiation therapy, occasionally can not be continued due to reasons of toxicity and/or poor response. Therefore, novel therapeutic optional approaches based on immunotherapy are being explored at present. This review describes and sums up the principles and the longstanding problems of peptide vaccine therapy, and demonstrates the results of clinical trials with colorectal cancer peptide vaccine therapy, including the authors' personal appraisal. In conclusion, the future prospects of peptide vaccine therapy are described.

Clinical and immunologic responses to active specific cancer vaccines in human colorectal cancer

Colorectal cancer is a common malignant disease, which, despite some progress, still requires improved therapeutic options. Several clinical studies have used active specific immunotherapy (i.e., vaccination) in colorectal cancer. However, the literature still lacks a comprehensive meta-analysis of this approach in advanced colorectal cancer. We did a systematic review with a meta-analysis of clinical studies to evaluate the objective clinical and immunologic response to active specific immunotherapy in patients with colorectal cancer. We conducted a search of Medline and the Web of Science, manually reviewed the literature, and consulted with experts. Criteria for including studies were colorectal cancer patients, active specific immunotherapy to induce a response directed against cancer or cancer antigens, an evaluable tumor burden (i.e., advanced or metastatic colorectal cancer), and precise classification of the patient, disease, and response. Response rates were assessed according to WHO criteria. Primary end points were the objective clinical response rate and the rate of immunologic responses. The secondary end point was the distribution of immune and clinical responses in relation to the route of vaccination and the type of vaccine. Thirty-two phase I/II studies reporting on 527 patients with advanced or metastatic colorectal cancer met all inclusion criteria. Pooled analysis showed an overall response rate (complete response + partial response) of 0.9% for advanced/metastatic colorectal cancer patients who underwent active specific immunization with a broad variety of substances (e.g., autologous tumor cells, peptide vaccine, dendritic cells, idiotypic antibody, and virus-based vaccine). Humoral immune responses were reported in 59%, and cellular ones were reported in 44% of the cases. Mixed or minor responses and disease stabilization are described in 1.9% and 8.3% of colorectal cancer patients, respectively. Pooled results of clinical trials reveal a very weak clinical response rate of <1% for active specific immunization procedures currently available for advanced colorectal cancer. Immune response induction is described in approximately half the patients.

Towards therapeutic vaccines for colorectal carcinoma: a review of clinical trials

Colorectal carcinoma is a leading cause of cancer-related mortality. Despite the introduction of new cytotoxic drugs, improved surgical and radiotherapeutic techniques, a large proportion of colorectal carcinomas remain incurable. New targeted therapeutic strategies, including immunotherapy, are being explored as complementary treatments. Recent advances in immunology and molecular biology have opened new avenues for the clinical testing of rationally designed vaccination strategies against cancer. The present report reviews the results of therapeutic vaccine trials in colorectal carcinoma, published mainly in the past 6 years. Tumor-associated antigens (self-antigens) have been targeted by therapeutic vaccination in more than 2000 colorectal carcinoma patients. The results demonstrate that tumor antigen-specific immune responses are reproducibly induced; that is, tolerance can be reversed, without the induction of serious adverse events or autoimmune disorders. No long-term autoimmune side effects have been observed after a minimum follow-up of 4 years in over 700 patients. Over 1300 colorectal carcinoma patients with minimal residual disease have been enrolled in randomized controlled Phase II/III trials using autologous tumor cell vaccines. A significantly improved overall survival was noted for Stages I-IV colorectal carcinoma patients utilizing Newcastle-disease virus as an adjuvant. Autologous tumor cells mixed with bacillus Calmette-Guerin (BCG) were of significant clinical benefit for patients with Stage II colon cancer. Results of randomized controlled trials targeting Ep-CAM have shown clinical benefit in subgroups of patients. Several new generation vaccines have demonstrated excellent safety profile and immunogenicity. Some studies have also demonstrated a statistically significant correlation between the induced immune response and prolonged overall survival, which should be confirmed in enlarged trials. Although it is unlikely that active specific immunotherapy will provide a standard complementary therapeutic approach for colorectal carcinoma in the near future, the results so far are encouraging. Randomized controlled vaccine trials targeting molecularly defined tumor antigens are warranted, particularly in colon carcinoma with minimal residual disease.

Adjuvant treatment strategies for early colon cancer

Colon cancer remains a major cause of death; however, in the last 3 years a number of trials have been published that have led to changes in the treatment of patients with this disease. Initially, the adjuvant treatment of patients following curative resection was based on their Dukes staging; this is now being refined by consideration of other pathological factors, as well as the investigation of newer prognostic markers such as p53, Ki67 and a number of genes on chromosome 18. Tumours generally develop from the progressive accumulation of genetic events, although some develop through mutation or inactivation of DNA mismatch repair proteins leading to microsatellite instability; this is particularly important in Lynch's syndrome. The loss of gene expression can occur by deletion or mutation of genes or by aberrant methylation of CpG islands. In patients with Dukes C colon cancer the standard of care for adjuvant chemotherapy was previously based on bolus fluorouracil (5-fluorouracil) and folinic acid (leucovorin) administered 5 days per month or weekly for 6 months. Recent studies with a combination of infusional fluorouracil, folinic acid and oxaliplatin have been found to be superior. A further study replacing fluorouracil with oral capecitabine has also demonstrated equivalent disease-free survival. Although some debate remains regarding the benefit of adjuvant treatment for patients with Dukes B colon cancer, the emerging consensus is that, for those patients who are younger and have high-risk features, chemotherapy should be discussed. A number of large vaccine trials have also been conducted in the adjuvant setting and, overall, these have been disappointing. This is a rapidly advancing area of therapy and the results of new trials are awaited to determine whether additional benefits can be achieved with biological therapies such as anti-vascular endothelial growth factor and anti-epithelial growth factor receptor monoclonal antibodies, which have already been shown to be effective in setting of metastatic colon cancer.

Intradermal injection of Newcastle disease virus-modified autologous melanoma cell lysate and interleukin-2 for adjuvant treatment of melanoma patients with resectable stage III disease

BACKGROUND

The value of active specific immunotherapy (ASI) for the treatment of solid tumours still has to be assessed. The objective was to test an autologous tumour cell vaccine for adjuvant treatment of stage III melanoma patients.

PATIENTS AND METHODS

After open vaccination of 12 patients, another 17 patients were recruited for a randomized double-blind trial comparing treatment with the vaccine (n = 9) and with a placebo (n = 8). Intracutaneous vaccinations were given postoperatively in weeks 2, 4, 6, 12, 24 and thereafter every 6 months if sufficient vaccine material was available. Patients were followed for 60-84 months.

RESULTS

Median disease-free survival time was 5 months for open-treated, 4 months for verum-treated and 6 months for placebo-treated patients. Corresponding median overall survival times were 30.5, 18 and 18.5 months, respectively. There were no remarkable differences between the verum and the placebo group.

CONCLUSIONS

Adjuvant treatment of melanoma patients with an autologous ASI vaccine did not show clinical efficacy in this cohort of melanoma patients.

Targeted therapy for colorectal cancer: mapping the way

In spite of the significant advances in conventional therapeutic approaches to colorectal cancer (CRC), most patients ultimately die of their disease. Dissecting the molecular mechanisms underlying CRC progression will not only accelerate the development of novel cancer-selective drugs but will also enable the therapeutic regimen to be personalized according to the molecular features of individual patients and tumors. Here, we report on the novel insights into CRC biology that are paving the way to the development of molecular therapies and summarize the results from recent clinical trials demonstrating that agents targeting tumor-specific molecular derangements can significantly improve the therapeutic efficacy of conventional chemotherapy. Only a broader clinical implementation of these concepts will provide patients with CRC the best chance of a cure.

Adjuvant therapy of colon cancer: current status and future developments

Options for the adjuvant therapy of resected stage III colon cancer have expanded beyond the previously well-accepted standard of 5-fluorouracil (5-FU) combined with leucovorin. The Xeloda in Adjuvant Colon Cancer Therapy (X-ACT) study confirmed that capecitabine (Xeloda) is at least as effective and is less toxic than a bolus 5-FU and leucovorin regimen for patients with stage III colon cancer. This study, in addition to National Surgical Adjuvant Breast and Bowel Project (NSABP) C-06, which demonstrated the equivalence of tegafur-uracil (UFT)/leucovorin with 5-FU/leucovorin, provides support for use of oral fluoropyrimidines for adjuvant therapy. Support for use of multiagent chemotherapy has been provided by the European MOSAIC study, which demonstrated a significant improvement in 3-year disease-free survival for the addition of oxaliplatin (Eloxatin) to infusional 5-FU and leucovorin (FOLFOX). Although adding irinotecan (Camptosar) to a bolus 5-FU and leucovorin regimen did not improve outcome in the adjuvant setting, the PETACC studies are evaluating the combination of infusional 5-FU, leucovorin, and irinotecan. In contrast to agreement on the appropriateness of therapy for stage III colon cancer, adjuvant therapy for patients with stage II disease remains controversial. Future advances in adjuvant therapy may include targeted therapies. Based on data demonstrating efficacy for the monoclonal antibodies bevacizumab (Avastin) and cetuximab (Erbitux) in the metastatic setting, clinical trials adding these agents to standard chemotherapy have been initiated in the adjuvant setting. Specifically, one U.S. cooperative group trial will evaluate the addition of bevacizumab to chemotherapy, a second will assess the addition of cetuximab, and a third trial will evaluate FOLFOX, infusional 5-FU/leucovorin (FOLFIRI), and FOLFOX followed by FOLFIRI. Finally, a study for patients with stage II disease and adverse prognostic factors will open. An important consideration in the new clinical trials is an assessment of molecular markers that either predict response or resistance to therapy or provide other prognostic information.

Immunization with mutant p53- and K-ras-derived peptides in cancer patients: immune response and clinical outcome

PURPOSE

To determine the ability to induce tumor-specific immunity with individual mutant K-ras-or p53-derived peptides and to monitor clinical outcome.

PATIENTS AND METHODS

Patients in varying stages of disease underwent genetic analysis for mutations in K-ras and p53. Thirty-nine patients were enrolled. Seventeen-mer peptides were custom synthesized to the corresponding mutation. Baseline immunity was assessed for cytotoxic T-lymphocyte (CTL) response and interferon gamma (IFN-gamma) release from mutant peptide-primed lymphocytes. Patients' peripheral-blood mononuclear cells were pulsed with the corresponding peptide, irradiated, and applied intravenously. Patients were observed for CTL, IFN-gamma, interleukin (IL) -2, IL-5, and granulocyte-macrophage colony-stimulating factor responses, for treatment-related toxicity, and for tumor response.

RESULTS

No toxicity was observed. Ten (26%) of 38 patients had detectable CTL against mutant p53 or K-ras, and two patients were positive for CTL at baseline. Positive IFN-gamma responses occurred in 16 patients (42%) after vaccination, whereas four patients had positive IFN-gamma reaction before vaccination. Of 29 patients with evident disease, five experienced a period of stable disease. Favorable prognostic markers were detectable CTL activity and a positive IFN-gamma reaction but not IL-5 release. Median survival times of 393 v 98 days for a positive versus negative CTL response (P = .04), respectively, and of 470 v 88 days for a positive versus negative IFN-gamma response (P = .02), respectively, were detected.

CONCLUSION

Custom-made peptide vaccination is feasible without any toxicity. CTL and cytokine responses specific to a given mutation can be induced or enhanced with peptide vaccines. Cellular immunity to mutant p53 and K-ras oncopeptides is associated with longer survival.

Immunotherapy for superficial bladder cancer

The treatment of superficial bladder cancer requires adjuvant therapies besides transurethral resection because of a high recurrence rate after this standard treatment alone. Current adjuvant therapies involve intravesical chemotherapy for patients at low and intermediate risk for recurrence and progression, and intravesical bacillus Calmette-Guérin for patients at intermediate and high risk. However, these adjuvant therapies fail in a significant number of patients, dictating the need for new and improved adjuvant treatment modalities for superficial bladder cancer. Immunotherapy aiming at the modulation of the immune system of the patient is a promising alternative adjuvant. This review discusses the current status of the clinical development of various immunotherapy approaches for superficial bladder cancer, including passive immunotherapy, immune stimulants, immunogene therapy and cancer vaccination.

Therapeutic vaccination in patients with gastrointestinal malignancies. A review of immunological and clinical results

Gastrointestinal (GI) malignancies are the most common types of human cancers. Despite the introduction of new cytotoxic drugs, a large proportion remains incurable. There is a great need to develop new complementary therapeutic modalities. Strategies exploiting targeted therapies are expanding. The focus of the present article is to review active specific immunotherapy (vaccination) in patients with GI malignancies. The review comprises a description of the immunogenicity of GI malignancies, various types of tumour antigens and mechanisms of action of cancer vaccines. Tumour escape from immune surveillance, vaccine strategies and adjuvants are also described. Clinical and immunological endpoints of cancer immunotherapy are outlined. Results of therapeutic vaccine trials published mainly during the last 5 years in PubMed enrolling a minimum of six patients with GI malignancies are included. Studies presented at the two last annual meetings of the American Society of Clinical Oncology are also covered. More than 2000 patients have been vaccinated with tumour antigens (self antigens). The procedure is safe and no autoimmune disorders have been observed after >4 years follow-up in a substantial number of patients. Humoral and cellular tumour antigen-specific immune responses were induced. A correlation between immune responses and prolonged overall survival was seen in several studies. The most encouraging results were noted in randomised controlled phase II/III trials including over 1300 colorectal carcinoma patients with minimal residual disease. A statistically significantly improved disease-free or overall survival was shown either in all vaccinated or in sub-groups of patients. Promising results were also reported in pancreatic and hepatocellular carcinoma. If the results of the randomised controlled trials hold true, active specific immunotherapy may provide a new promising targeted therapeutic approach in GI malignancies with minimal toxicity. Further enlarged randomised controlled studies are warranted to confirm the results, particularly in colon carcinoma with minimal residual disease.

Adjuvant therapy for stage II colon cancer: an elephant in the living room?

At present, standard adjuvant treatment for patients with stage III colon cancer after surgical resection is represented by 6 months of chemotherapy based on 5-fluorouracil/leucovorin regimens. Even elderly patients enjoy the benefit of chemotherapy in terms of superior overall survival with no detrimental effects on quality of life. More questionable is the role of adjuvant chemotherapy for stage II colon cancer patients, the standard of care for whom is surgical resection alone. Although a majority of patients will be cured with resection, a significant minority will ultimately relapse, suggesting the need to identify patients who may benefit from adjuvant therapy. Putative prognostic markers for stage II patients, as well as the state-of-the-art of the adjuvant treatment in this setting, are reviewed in this paper.

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.

Undefined-antigen vaccines

Our knowledge of the immune system and how it interacts with tumor cells continues to grow. With each advance in basic science comes a new opportunity to develop an effective treatment strategy. Many such opportunities have arisen in the past few decades and this chapter has attempted to describe how these new advances have been combined with a variety of undefined cellular antigen preparations in an attempt to develop effective cancer vaccines. None of the strategies described in this chapter have been sufficiently effective to become part of standard therapy. However, the approaches tested have generally been well-tolerated by patients with advanced cancer and the evidence of immunologic activity and examples of impressive clinical activity in a wide variety of malignancies, suggests that these strategies can be the building blocks upon which new advances are added and effective treatments developed.

Colorectal cancer vaccines: principles, results, and perspectives

In the search for novel therapeutic approaches to treat patients with colorectal carcinoma, anticancer vaccination holds promise. A large body of preclinical and clinical evidence has demonstrated that the immune system can be polarized against malignant cells by means of several active specific immunotherapy strategies. Although no vaccination regimen can be currently recommended outside clinical trials, tumor response and immunologic findings observed in animal models and humans prompt researchers to explore further the antitumor potential of such biotherapy in an effort to reproduce in a larger set of patients the cascade of molecular events that characterizes the successful tumor immune rejection currently observed in a minority of vaccinated subjects. In this work, we summarize the principles and the main results of cancer vaccine strategies so far implemented for the treatment of patients with colorectal carcinoma. We also discuss the most recent preclinical tumor immunology insights that might change the way to design the next generation of cancer vaccines, hopefully improving the effectiveness of such a biotherapeutic approach.

Cancer vaccine development: on the way to break immune tolerance to malignant cells

Exploiting a naturally occurring defense system, the immunotherapeutic approach embodies an ideal nontoxic treatment for cancer. Despite the evidence that immune effectors can play a significant role in controlling tumor growth either in natural conditions or in response to therapeutic manipulation, the cascade of molecular events leading to tumor rejection by the immune system remains to be fully elucidated. Nevertheless, some recent tumor immunology advancements might drastically change the way to design the next generation of cancer vaccines, hopefully improving the effectiveness of this therapeutic approach. In the present work, we will focus on three main areas of particular interest for the development of novel vaccination strategies: (a) cellular or molecular mechanisms of immune tolerance to malignant cells; (b) synergism between innate and adaptive immune response; (c) tumor-immune system interactions within the tumor microenvironment.

A systemic antitumor immune response prevents outgrowth of lung tumors after i.v. rechallenge but is not able to prevent growth of experimental liver tumors

Although a systemic antitumor immune response by antibodies or T cells is often detected in cancer patients, this response mostly does not result in tumor rejection. The beneficial effect of tumor vaccination on survival rates is limited as tumor response is low. In contrast to solid tumors, circulating tumor cells may be more easily accessible and therefore destroyed by the immune system and thus prevent metastases. This discrepancy is further clarified in our study, by assessing the effect of a systemic immune response on established liver tumors and circulating tumor cells. Male Wag/Rij rats were inoculated with CC531 colorectal tumor cells subcapsulary in the liver, with or without immune suppression (60 mg/kg cyclophosphamide). To study the effect of a systemic immune response, rats received CC531 tumor cells intravenously and three weeks later the number of lung tumors was assessed. Presence of specific anti-CC531 antibodies in serum was determined by flow cytometric analysis at times of inoculation, i.v. tumor cell administration and sacrifice. Rats with liver tumors and subsequent rechallenge produced anti-CC531 IgG antibodies and did not develop lung tumors, whereas without existing liver tumors, rats developed lung tumors upon i.v. administration of CC531 tumor cells. Liver tumors in rats with and without i.v. CC531 tumor cell administration were equal in size. These results showed that a systemic immune response, induced upon liver tumor induction and rechallenge, prevented formation of lung tumors but did not affect tumor growth in the liver. Possibly the immune response lacked the ability to penetrate the protective extracellular matrix surrounding the established liver tumors, which prevented the tumor cells from recognition by and contact with cells of the immune system.

A Theoretical Approach for T-Lymphocyte Monitoring of Autologous Cancer Vaccine Therapy Using Autologous HLA-Class I and HLA-Class II Constructs

It is desirable to have in vitro surrogate endpoints that reflect changes in cellular immunity in patients who are undergoing treatment with anticancer, autologous, tumor-cell vaccines. The tetramer assay appears to be useful for monitoring T-lymphocyte responses to a single, specific, known tumor peptide antigen, but cell-based vaccines may express multiple tumor-associated antigens that are important in a host immune response to their own cancer. We describe a hypothetical alternative to the standard artificial tetramer assay, that has the potential to detect CD4+ and CD8+ T-lymphocytes that react with any peptides expressed in the context of HLA-class I or HLA-class II. Such an assay should enable monitoring for specific T-lymphocyte antitumor activity in patients being treated with patient specific, autologous, tumor-cell vaccines.

Adjuvant therapy for stage II colon cancer: a systematic review from the Cancer Care Ontario Program in evidence-based care's gastrointestinal cancer disease site group

PURPOSE

To develop a systematic review that would address the following question: Should patients with stage II colon cancer receive adjuvant therapy?

METHODS

A systematic review was undertaken to locate randomized controlled trials comparing adjuvant therapy to observation.

RESULTS

Thirty-seven trials and 11 meta-analyses were included. The evidence for stage II colon cancer comes primarily from a trial of fluorouracil plus levamisole and a meta-analysis of 1,016 patients comparing fluorouracil plus folinic acid versus observation. Neither detected an improvement in disease-free or overall survival for adjuvant therapy. A recent pooled analysis of data from seven trials observed a benefit for adjuvant therapy in a multivariate analysis for both disease-free and overall survival. The disease-free survival benefits appeared to extend to stage II patients; however, no P values were provided. A meta-analysis of chemotherapy by portal vein infusion has also shown a benefit in disease-free and overall survival for stage II patients. A meta-analysis was conducted using data on stage II patients where data were available (n = 4,187). The mortality risk ratio was 0.87 (95% CI, 0.75 to 1.01; P =.07).

CONCLUSION

There is preliminary evidence indicating that adjuvant therapy is associated with a disease-free survival benefit for patients with stage II colon cancer. These benefits are small and not necessarily associated with improved overall survival. Patients should be made aware of these results and encouraged to participate in active clinical trials. Additional investigation of newer therapies and more mature data from the presently available trials should be pursued.

Tolerance and cancer: mechanisms of tumor evasion and strategies for breaking tolerance

The development of malignant disease might be seen as a failure of immune surveillance. However, not all tumors are naturally immunogenic, and even among those that are immunogenic, the uncontrolled rapid growth of a tumor may sometimes out-run a robust immune response. Nevertheless, recent evidence suggests that mechanisms of tolerance that normally exist to prevent autoimmune disease may also preclude the development of an adequate antitumor response and that tumors themselves have the ability to thwart the development of effective immune responses against their antigens. A major challenge has been to develop approaches to breaking this tolerance in tumor-bearing hosts, and recent advances in our understanding of antigen presentation and tolerance have led to some promising strategies. An alternative approach is to use T cells from nontumor-bearing, allogeneic hosts in the form of lymphocyte infusions, with or without hematopoietic cell transplantation. Immunotherapy may occur in this setting via the response of nontolerant, tumor antigen-specific T cells from nontumor-bearing hosts or via the powerful destructive effect of an alloresponse directed against antigens shared by malignant cells in the recipient. Approaches to exploiting this beneficial effect without the deleterious consequence of graft-versus-host disease in allogeneic hematopoietic cell recipients are discussed.

Indications et modalités de la chimiothérapie adjuvante des cancers du côlon

Within the past 12 years, many progresses have been performed in adjuvant chemotherapy of colon cancer. 5FU + levamisole was first considered as standard treatment in the early 1990s, then FUFOL and later LV5FU2. More recently, FOLFOX4 achieves a better disease-free survival at 3 years as compared to LV5FU2, and should now be considered as a standard treatment. Adjuvant chemotherapy is recommended for 6 months for stage III patients. It is an option for stage II patients. Elderly patients could be treated according to the same modalities as younger patients, based on physiological age and relative contra-indications from associated diseases.

Randomized comparative study of surgical adjuvant chemotherapy using 5-fluorouracil and dl-leucovorin with CDDP, 5-FU and dl-leucovorin for advanced colorectal cancer

BACKGROUND

5-fluorouracil (5-FU) is the most useful chemotherapeutic agent for colorectal carcinoma. Recently, the effectiveness of multidrug therapy in modifying the anticancer activity of 5-FU for advanced cases was clarified. We conducted a randomized comparative study of surgical adjuvant chemotherapy comparing cis-diamminedichloroplatinum (CDDP), 5-FU and dl-leucovorin (LV) (PFL therapy) with dl-LV and 5-FU (FL therapy) in patients who underwent curative resection of stage II and III colorectal carcinoma.

METHODS

Thirty-one patients, 13 ungergoing PFL therapy and 18 undergoing FL therapy, completed the scheduled administration, while 20 dropped out. Administration schedules were as follows: PFL therapy consisted of 13 mg/m2 CDDP, 300 mg/m2 5-FU and 30 mg/body weight LV for 5 consecutive days. The FL therapy consisted of 300 mg/m2 5-FU and 30 mg/body weight LV for 5 consecutive days in hospital. Both regimens were followed by biweekly administration of the same dosages of LV and 5-FU in an outpatient setting.

RESULTS

Seven of 23 patients in the PFL therapy group and five of 28 patients in the FL therapy group experienced recurrence of colorectal carcinomas. Regarding prognosis of stage II patients, both groups showed similar results in 5-year disease specific survival and disease-free survival. However, stage III patients obtained better prognostic results in the FL therapy group than in the PFL therapy group. Major toxicities in these regimens were vomiting and leukopenia, both being more frequent in the PFL therapy group. Symptoms of toxicity resolved completely in all patients.

CONCLUSION

From the present study we found that PFL therapy brought no benefit for stage II and III colorectal carcinoma compared with FL therapy. We should search for more appropriate adjuvant therapy, increasing the therapeutic effect of 5-FU + LV for stage II and III colorectal carcinoma.

Cancer vaccines

OBJECTIVE

To provide a review of cancer vaccines, how they work, and the current state of the science underlying these treatments.

DATA SOURCES

Research studies, review articles, book chapters, personal communications.

CONCLUSION

Vaccines have been studied in a variety of malignancies; however, melanoma has provided the best tumor model for vaccination. Clinical trials continue to investigate the optimal vaccine, route, and immunization schedule.

IMPLICATIONS FOR NURSING PRACTICE

Oncology nurses must grasp a widening array of therapeutic options for cancer patients. The educational needs of the patient will be better met through a thorough understanding of basic concepts of newer cancer therapies.

An overview of targeted treatments in cancer

BACKGROUND

The concept behind cancer treatment has evolved over the past decade from systemic, nonspecific, high-dose chemotherapy to targeted therapy and the introduction of cancer vaccines. Advanced technology and a better understanding of the cellular mechanisms that control cancer biology have helped in the development of such targeted treatment.

OBJECTIVE

The aim of this article was to review some of the new and commonly used targeted treatments in cancer, emphasizing their mechanisms of action, safety profiles, and clinical applications.

METHODS

The terms cancer, chemotherapy, monoclonal antibodies, targeted treatment, tyrosine kinase, epidermal growth factors, epidermal growth factor receptor, and cancer vaccines were used to search MEDLINE for English-language studies in humans, published between 1966 and March 2003. Identified publications addressing the objectives of this article were selected for review.

RESULTS

All-trans-retinoic acid, imatinib, gemtuzumab ozogamicin, rituximab, alemtuzumab, trastuzumab, cetuximab, and gefitinib are recently developed cancer therapies that target specific types of cells and receptors. They have been used in a variety of hematologic and solid tumors, and their tolerability makes them attractive for use even in elderly and extensively pretreated patients. Vaccines using dendritic cells, tumor cells, and fusions of tumor cells and antigen-presenting cells have also shown some promise in research, but further study is needed to obtain better, sustained results.

CONCLUSIONS

Targeted treatment and cancer vaccines are novel approaches in the treatment of cancer. Both fields are expanding rapidly, with new technology and ongoing medical research. The clinical implications of such agents, administered either solely or in combination with established chemotherapeutic agents, may ultimately lead to better regimens and improved clinical responses.

Immunotherapy of cancer by active vaccination: does allogeneic bone marrow transplantation after non-myeloablative conditioning provide a new option?

The critical role of antigen-specific T cells in cancer immunotherapy has been amply demonstrated in many model systems. Though success of clinical trials still remains far behind expectation, the continuous improvement in our understanding of the biology of the immune response will provide the basis of optimized cancer vaccines and allow for new modalities of cancer treatment. This review focuses on the current status of active therapeutic vaccination and future prospects. The latter will mainly be concerned with allogeneic bone marrow cell transplantation after non-myeloablative conditioning, because it is my belief that this approach could provide a major breakthrough in cancer immunotherapy. Concerning active vaccination protocols the following aspects will be addressed: i) the targets of immunotherapeutic approaches; ii) the response elements needed for raising a therapeutically successful immune reaction; iii) ways to achieve an optimal confrontation of the immune system with the tumor and iv) supportive regimen of immunomodulation. Hazards which one is most frequently confronted with in trials to attack tumors with the inherent weapon of immune defense will only be briefly mentioned. Many question remain to be answered in the field of allogeneic bone marrow transplantation after non-myeloablative conditioning to optimize the therapeutic setting for this likely very powerful tool of cancer therapy. Current considerations to improve engraftment and to reduce graft versus host disease while strengthening graft versus tumor reactivity will be briefly reviewed. Finally, I will discuss whether tumor-reactive T cells can be "naturally" maintained during the process of T cell maturation in the allogeneic host. Provided this hypothesis can be substantiated, a T cell vaccine will meet a pool of virgin T cells in the allogeneically reconstituted host, which are tolerant towards the host, but not anergised towards tumor antigens presented by MHC molecules of the host.

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.

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.

Cancer vaccines

Although cancer immunotherapy was initiated by William Coley more than a century ago, the field of cancer vaccines is in an early stage of development. Only recently, major advances in cellular and molecular immunology have allowed a comprehensive understanding of the complex and high rate of interactions between the immune system and tumor cells. We have learned that these tumor-immune system interactions may result either in strong immune antitumor response or tolerance to tumor-associated antigens. This article will discuss the profound interest in cancer vaccines derived from their potential to induce antitumor responses in vivo. Substantial data from several preclinical models and early human clinical trials have confirmed the ability of cancer vaccines to induce immune responses that are tumor-specific and, in some cases, associated with clinical responses. One future challenge will be to determine how to appropriately stimulate the pathways leading to effective interaction among antigen-presenting cells, T lymphocytes, and tumor cells. It also is critical to develop monitoring strategies that may allow the identification of patients who may benefit from cancer vaccines.

Overview of the clinical efficacy of investigational anticancer drugs

The purpose of this overview was to make a broad inventory of investigational drugs for medicinal cancer treatment and, specifically, to indicate the evidence of clinical efficacy. Information was retrieved from electronic database searches in Medline and CANCERLIT and relevant published reviews. As the most recent findings are first reported as conference abstracts, an important basis for identification of new drugs and clinical results was a hand search of 13,392 abstracts from five major recent cancer conferences. A total of 209 investigational approaches or drugs were identified and classified into one of eight groups according to proposed mechanism of action. For 28 drugs/approaches survival data were available from randomized controlled trials. Statistically significant benefit was observed for only 12. In earlier phases no or modest anticancer activity was reported. It is speculated that the expanding knowledge in tumour biology might not easily translate into new substantially better anticancer drugs.

Making use of the primary tumour

Surgical resection of a primary tumour is often not sufficient to cure a patient. Even when no residual cancer can be detected at time of surgery, metastases may appear in the following years, which indicates that the primary tumour had apparently spread before surgery. Following surgery, systemic chemotherapy may be used to eradicate micro-metastatic disease. Here we present two unconventional strategies that implement new insights into tumour biology and tumour immunology in the treatment of patients with cancer. Both experimental strategies use the individual characteristics of the patient's primary tumour to optimise the control of life-threatening micro-metastases. We aim to modulate the patient's adaptive immune system, targeting it towards the patient's own tumour cells to eradicate residual disease following local treatment. In one approach, this is done by autologous tumour cell vaccinations as adjuvant treatment for colon cancer patients and, in a second approach, by giving chemo-immunotherapy before local treatment to women with locally advanced breast cancer.

Adjuvant treatment of colorectal cancer (current expert opinion derived from the Third International Conference: Perspectives in Colorectal Cancer, Dublin, 2001)

This article summarises the progress that has been made in the adjuvant treatment of colorectal cancer over the last decade. In view of the consequent improvements in recurrence rates and in overall survival, the development of effective adjuvant treatments for colorectal cancer is considered as one of the most important to be made in clinical oncology over the last decade. Treatment recommendations based on evidence-based data and on expert opinions are summarised in this manuscript. However, a consensus cannot be reached on all aspects of treatment because of data that is currently emerging that will influence clinical practice and because of the many ongoing clinical trials. Those involved in the treatment of colorectal cancer should therefore be encouraged to continue to provide optimal patient care and to participate in well designed clinical trials in order to increase the evidence upon which they can base their clinical judgements and in order to make further progress.

Biological therapy of colorectal cancer

In this review, the immunogenicity of colorectal cancer (CRC) and the results of clinical and recent preclinical studies are discussed. Evidence for immune reactivity has been found in several preclinical models and the prognostic value of some of these immune responses have been reported. The possible mechanisms are discussed. Treatment with monoclonal antibodies is still experimental; as previously described benefit of treatment with monoclonal antibodies could not be confirmed. Labelled monoclonal antibody therapy has produced mixed results and also need further investigation. Several antigens are used in active specific immunotherapy (ASI). Its targets and modifications are discussed, as are their use in clinical studies. Although some of the results are promising, the results still have to be confirmed in larger studies. Since there is sufficient evidence for immune reactivity in CRC, further research on immunotherapeutic strategies is justified and will be focused on the development of humanised antibodies, the search for other relevant T-cell epitopes and ways to induce a more effective T cell response.