Clinical outcome of breast and ovarian cancer patients treated with high-dose chemotherapy, autologous stem cell rescue and THERATOPE STn-KLH cancer vaccine

Therapeutic potential of toll-like receptors in treatment of gynecological cancers

Toll-like receptors (TLRs) play an important role in the innate and adaptive immune system. They are expressed in various regions of the female reproductive tract, and their regulation may be involved in the pathogenesis of gynecological lesions. There is growing evidence that ligands for several TLRs are potentially anticancer agents, some of which have already been approved by the FDA, and these compounds are now undergoing clinical evaluation. There is a rationale for using these ligands as adjuvants in the treatment or prevention of gynecological cancer. Some TLR agonists that are of potential interest in the treatment of gynecological lesions include imiquimod, motolimod, cervarix, and CpG-oligodeoxynucleotides (ODNs). In this review, we outline the different functions of TLRs in gynecological cancer with particular emphasis on the value of TLR agonists as a potential therapeutic target in the treatment of gynecological cancer. © 2019 IUBMB Life, 71(5):549-564, 2019.

Antigen-specific active immunotherapy for ovarian cancer

BACKGROUND

This is the second update of the review first published in the Cochrane Library (2010, Issue 2) and later updated (2014, Issue 9).Despite advances in chemotherapy, the prognosis of ovarian cancer remains poor. Antigen-specific active immunotherapy aims to induce tumour antigen-specific anti-tumour immune responses as an alternative treatment for ovarian cancer.

OBJECTIVES

Primary objective• To assess the clinical efficacy of antigen-specific active immunotherapy for the treatment of ovarian cancer as evaluated by tumour response measured by Response Evaluation Criteria In Solid Tumors (RECIST) and/or cancer antigen (CA)-125 levels, response to post-immunotherapy treatment, and survival differences◦ In addition, we recorded the numbers of observed antigen-specific humoral and cellular responsesSecondary objective• To establish which combinations of immunotherapeutic strategies with tumour antigens provide the best immunological and clinical results SEARCH METHODS: For the previous version of this review, we performed a systematic search of the Cochrane Central Register of Controlled Trials (CENTRAL; 2009, Issue 3), in the Cochrane Library, the Cochrane Gynaecological Cancer Group Specialised Register, MEDLINE and Embase databases, and clinicaltrials.gov (1966 to July 2009). We also conducted handsearches of the proceedings of relevant annual meetings (1996 to July 2009).For the first update of this review, we extended the searches to October 2013, and for this update, we extended the searches to July 2017.

SELECTION CRITERIA

We searched for randomised controlled trials (RCTs), as well as non-randomised studies (NRSs), that included participants with epithelial ovarian cancer, irrespective of disease stage, who were treated with antigen-specific active immunotherapy, irrespective of type of vaccine, antigen used, adjuvant used, route of vaccination, treatment schedule, and reported clinical or immunological outcomes.

DATA COLLECTION AND ANALYSIS

Two reviews authors independently extracted the data. We evaluated the risk of bias for RCTs according to standard methodological procedures expected by Cochrane, and for NRSs by using a selection of quality domains deemed best applicable to the NRS.

MAIN RESULTS

We included 67 studies (representing 3632 women with epithelial ovarian cancer). The most striking observations of this review address the lack of uniformity in conduct and reporting of early-phase immunotherapy studies. Response definitions show substantial variation between trials, which makes comparison of trial results unreliable. Information on adverse events is frequently limited. Furthermore, reports of both RCTs and NRSs frequently lack the relevant information necessary for risk of bias assessment. Therefore, we cannot rule out serious biases in most of the included trials. However, selection, attrition, and selective reporting biases are likely to have affected the studies included in this review. GRADE ratings were high only for survival; for other primary outcomes, GRADE ratings were very low.The largest body of evidence is currently available for CA-125-targeted antibody therapy (17 studies, 2347 participants; very low-certainty evidence). Non-randomised studies of CA-125-targeted antibody therapy suggest improved survival among humoral and/or cellular responders, with only moderate adverse events. However, four large randomised placebo-controlled trials did not show any clinical benefit, despite induction of immune responses in approximately 60% of participants. Time to relapse with CA-125 monoclonal antibody versus placebo, respectively, ranged from 10.3 to 18.9 months versus 10.3 to 13 months (six RCTs, 1882 participants; high-certainty evidence). Only one RCT provided data on overall survival, reporting rates of 80% in both treatment and placebo groups (three RCTs, 1062 participants; high-certainty evidence). Other small studies targeting many different tumour antigens have presented promising immunological results. As these strategies have not yet been tested in RCTs, no reliable inferences about clinical efficacy can be made. Given the promising immunological results and the limited side effects and toxicity reported, exploration of clinical efficacy in large well-designed RCTs may be worthwhile.

AUTHORS' CONCLUSIONS

We conclude that despite promising immunological responses, no clinically effective antigen-specific active immunotherapy is yet available for ovarian cancer. Results should be interpreted cautiously, as review authors found a significant dearth of relevant information for assessment of risk of bias in both RCTs and NRSs.

Ru-catalyzed sequence for the synthesis of cyclic amido-ethers

Efficient synthesis of versatile building blocks for enabling medicinal chemistry research has always challenged synthetic chemists to develop innovative methods. Of particular interest are the methods that are amenable to the synthesis of chemically distinct and diverse classes of pharmaceutically relevant motifs. Herein we report a general method for the one-pot synthesis of cyclic α-amido-ethers containing different amide functionalities including lactams, tetramic acids and amino acids. For the incorporation of the nucleotide bases, a chemo and regioselective palladium-catalyzed transformation has been developed, providing rapid access to nucleoside analogs.

Antigen-specific active immunotherapy for ovarian cancer

BACKGROUND

Despite advances in chemotherapy, prognosis of ovarian cancer remains poor. Antigen-specific active immunotherapy aims to induce tumour-antigen-specific anti-tumour immune responses as an alternative treatment for ovarian cancer.

OBJECTIVES

To assess the feasibility of antigen-specific active immunotherapy for ovarian cancer. Primary outcomes are clinical efficacy and antigen-specific immunogenicity with carrier-specific immunogenicity and side effects as secondary outcomes.

SEARCH METHODS

For the previous version of this review, a systematic search of the Cochrane Central Register of Controlled Trials (CENTRAL) 2009, Issue 3, Cochrane Gynaecological Cancer Group Specialized Register, MEDLINE and EMBASE databases and clinicaltrials.gov was performed (1966 to July 2009). We conducted handsearches of the proceedings of relevant annual meetings (1996 to July 2009).For this update of the review the searches were extended to October 2013.

SELECTION CRITERIA

Randomised controlled trials (RCTs), as well as non-randomised non-controlled studies that included participants with epithelial ovarian cancer, irrespective of stage of disease, and treated with antigen-specific active immunotherapy, irrespective of type of vaccine, antigen used, adjuvant used, route of vaccination, schedule, and reported clinical or immunological outcomes.

DATA COLLECTION AND ANALYSIS

Two reviews authors independently performed the data extraction. Risk of bias was evaluated for RCTs according to standard methodological procedures expected by The Cochrane Collabororation or for non-RCTs using a selection of quality domains deemed best applicable to the non-randomised non-controlled studies.

MAIN RESULTS

Fifty-five studies were included (representing 3051 women with epithelial ovarian cancer). Response definitions showed substantial variation between trials, which makes comparison of trial results unreliable. Information on adverse events was frequently limited. Furthermore, reports of both RCTs and non-RCTs frequently lacked the relevant information necessary to assess risk of bias. Serious biases in most of the included trials can therefore not be ruled out.The largest body of evidence is currently available for CA-125 targeted antibody therapy (16 studies: 2339 participants). Non-RCTs of CA-125 targeted antibody therapy suggests increased survival in humoral and/or cellular responders. However, four large randomised placebo-controlled trials did not show any clinical benefit despite induction of immune responses in approximately 60% of participants.Other small studies targeting many different tumour antigens showed promising immunological results. As these strategies have not yet been tested in RCTs, no reliable inferences about clinical efficacy can be made. Given the promising immunological results, limited side effects and toxicity exploration of clinical efficacy in large well-designed RCTs may be worthwhile.

AUTHORS' CONCLUSIONS

We conclude that despite promising immunological responses, no clinically effective antigen-specific active immunotherapy is yet available for ovarian cancer. Results should be interpreted cautiously as there was a significant lack of relevant information for the assessment of risk of bias in both RCTs and non-RCTs.

Vaccine immunotherapy in breast cancer treatment: promising, but still early

Cancer vaccine-based immunotherapy should potentiate immunosurveillance function, preventing and protecting against growing tumors. Tumor cells usually activate the immune system, including T lymphocytes and natural killer cells, which are able to eliminate the transformed cells. Immunosubversion mechanisms related to tumor cells antigenic immunoediting induces mechanisms of tolerance and immunoescape. This condition impairs not only host-generated immunosurveillance, but also attempts to harness the immune response for therapeutic purposes. Most trials evaluating breast cancer vaccines have been carried out in patients in the metastatic and adjuvant setting. The aim of this review is to analyze the activity of vaccination strategies in current clinical trials. We summarize the differential approaches, protein-based and cell-based vaccines, focusing on vaccines targeting HER2/neu protein. Another focus of the review is to provide the reader with future challenges in the field, taking into account both the immunological and clinical aspects to better target the goal.

Formulation of abalone hemocyanin with high antiviral activity and stability

Hemocyanin has been shown to have potential antiviral activity against herpes simplex virus type-1. However, current liquid formulations have short shelf life and high risk of bacterial contamination. The aim of our study was to develop a stable functional formulation. Analytical techniques (nano-differential scanning calorimetry and spectroscopy) and biological assays (cytotoxicity and plaque reduction) were employed to measure the effect of sugar addition on the physical properties and shelf life of the solid formulated hemocyanin. Sucrose improved thermal stability significantly by both increasing the aggregation onset temperature (70°C to>78 °C) and enhancing the activation energy (18%). Lyophilisation without trehalose caused degradation and unfolding of the α-helices of hemocyanin. However, the addition of an optimal proportion of trehalose:protein (5:1 by weight) prevented the degradation and unfolding during lyophilisation, hence maintained the protein solubility. The estimated ED50 values of the formulated solid (0.43±0.1) and liquid samples (0.37±0.06) were similar in magnitude, and were significantly lower than the respective controls; thus, confirming enhanced antiviral activity of the formulation. Formulated compounds were stable for six months at 5 °C storage. The enhanced shelf life and stable antiviral activity of the formulation offers its significant potential as effective therapeutic agent in future clinical applications.

Tumor-associated antigens in breast cancer

The targets for the immune system are antigens present on cancer cells; however, many are not cancer-specific and may also be found on normal tissues. These antigens are often products of mutated cellular genes, aberrantly expressed normal genes, or genes encoding viral proteins. Vaccines constitute an active and specific immunotherapy designed to stimulate the intrinsic antitumor immune response by presenting tumor-associated antigens expressed on normal tissues that are overexpressed on tumor cells.

A Phase I vaccine trial using dendritic cells pulsed with autologous oxidized lysate for recurrent ovarian cancer

Purpose

Ovarian cancer, like most solid tumors, is in dire need of effective therapies. The significance of this trial lies in its promise to spearhead the development of combination immunotherapy and to introduce novel approaches to therapeutic immunomodulation, which could enable otherwise ineffective vaccines to achieve clinical efficacy.

Rationale

Tumor-infiltrating T cells have been associated with improved outcome in ovarian cancer, suggesting that activation of antitumor immunity will improve survival. However, molecularly defined vaccines have been generally disappointing. Cancer vaccines elicit a modest frequency of low-to-moderate avidity tumor-specific T-cells, but powerful tumor barriers dampen the engraftment, expansion and function of these effector T-cells in the tumor, thus preventing them from reaching their full therapeutic potential. Our work has identified two important barriers in the tumor microenvironment: the blood-tumor barrier, which prevents homing of effector T cells, and T regulatory cells, which inactivate effector T cells. We hypothesize that cancer vaccine therapy will benefit from combinations that attenuate these two barrier mechanisms.

Design

We propose a three-cohort sequential study to investigate a combinatorial approach of a new dendritic cell (DC) vaccine pulsed with autologous whole tumor oxidized lysate, in combination with antiangiogenesis therapy (bevacizumab) and metronomic cyclophosphamide, which impacts Treg cells.

Innovation

This study uses a novel autologous tumor vaccine developed with 4-day DCs pulsed with oxidized lysate to elicit antitumor response. Furthermore, the combination of bevacizumab with a whole tumor antigen vaccine has not been tested in the clinic. Finally the combination of bevacizumab and metronomic cyclophosphamide in immunotherapy is novel.

Sialyl-tn in cancer: (how) did we miss the target?

Sialyl-Tn antigen (STn) is a short O-glycan containing a sialic acid residue α2,6-linked to GalNAcα-O-Ser/Thr. The biosynthesis of STn is mediated by a specific sialyltransferase termed ST6GalNAc I, which competes with O-glycans elongating glycosyltransferases and prevents cancer cells from exhibiting longer O-glycans. While weakly expressed by fetal and normal adult tissues, STn is expressed by more than 80% of human carcinomas and in all cases, STn detection is associated with adverse outcome and decreased overall survival for the patients. Because of its pan-carcinoma expression associated with an adverse outcome, an anti-cancer vaccine, named Theratope, has been designed towards the STn epitope. In spite of the great enthusiasm around this immunotherapy, Theratope failed on Phase III clinical trial. However, in lieu of missing this target, one should consider to revise the Theratope design and the actual facts. In this review, we highlight the many lessons that can be learned from this failure from the immunological standpoint, as well as from the drug design and formulation and patient selection. Moreover, an irrefutable knowledge is arising from novel immunotherapies targeting other carbohydrate antigens and STn carrier proteins, such as MUC1, that will warrantee the future development of more successful anti-STn immunotherapy strategies.

The interaction between Siglec-15 and tumor-associated sialyl-Tn antigen enhances TGF-β secretion from monocytes/macrophages through the DAP12-Syk pathway

We previously demonstrated that Siglec-15, a member of the Siglec family of glycan-recognition proteins, is expressed on a subset of macrophages and preferentially recognizes the sialyl-Tn (sTn) antigen, a tumor-associated glycan structure. In this study, we report on the biological significance of the Siglec-15-mediated interaction between monocytes/macrophages and cancer cells. Siglec-15 is expressed on tumor-associated macrophages (TAMs) in various human tumor tissues. We further demonstrated that its expression is substantially elevated in macrophage colony-stimulating factor-induced M2-like macrophages, which produced more transforming growth factor-β (TGF-β) in response to sTn-positive cells than to negative cells. We designed a co-culture model of THP-1 (human monocytic leukemia) cells and H157 (human lung carcinoma) cells mimicking the interaction between monocytes/macrophages and cancer cells that recapitulated the enhanced TGF-β production in Siglec-15 expressing THP-1 cells by the cellular interaction with sTn expressing H157 cells. The enhanced TGF-β production required a direct interaction between the two cell lines through sialic acids. Siglec-15 associates with adaptor protein DNAX activation protein of 12 kDa (DAP12) at the binding determinant Lys(274) in the transmembrane domain and transduces a signal to spleen tyrosine kinase (Syk). The enhanced TGF-β secretion was significantly attenuated by Syk inhibitor treatment of THP-1 cells or by substitution of the Siglec-15 Lys(274) to Ala, which disrupts the molecular interaction between Siglec15 and DAP12. These findings indicate that Siglec-15 recognizes the tumoral sTn antigen and transduces a signal for enhanced TGF-β secretion in TAMs and further suggest that Siglec-15 on macrophages may contribute to tumor progression by the TGF-β-mediated modulation of intratumoral microenvironments.

Recent advances in developing synthetic carbohydrate-based vaccines for cancer immunotherapies

Cancer cells can often be distinguished from healthy cells by the expression of unique carbohydrate sequences decorating the cell surface as a result of aberrant glycosyltransferase activity occurring within the cell; these unusual carbohydrates can be used as valuable immunological targets in modern vaccine designs to raise carbohydrate-specific antibodies. Many tumor antigens (e.g., GM2, Ley, globo H, sialyl Tn and TF) have been identified to date in a variety of cancers. Unfortunately, carbohydrates alone evoke poor immunogenicity, owing to their lack of ability in inducing T-cell-dependent immune responses. In order to enhance their immunogenicity and promote long-lasting immune responses, carbohydrates are often chemically modified to link to an immunogenic protein or peptide fragment for eliciting T-cell-dependent responses. This review will present a summary of efforts and advancements made to date on creating carbohydrate-based anticancer vaccines, and will include novel approaches to overcoming the poor immunogenicity of carbohydrate-based vaccines.

Cancer vaccines and carbohydrate epitopes

Tumor-associated carbohydrate antigens (TACA) result from the aberrant glycosylation that is seen with transformation to a tumor cell. The carbohydrate antigens that have been found to be tumor-associated include the mucin related Tn, Sialyl Tn, and Thomsen-Friedenreich antigens, the blood group Lewis related Lewis(Y), Sialyl Lewis(X) and Sialyl Lewis(A), and Lewis(X) (also known as stage-specific embryonic antigen-1, SSEA-1), the glycosphingolipids Globo H and stage-specific embryonic antigen-3 (SSEA-3), the sialic acid containing glycosphingolipids, the gangliosides GD2, GD3, GM2, fucosyl GM1, and Neu5GcGM3, and polysialic acid. Recent developments have furthered our understanding of the T-independent type II response that is seen in response to carbohydrate antigens. The selection of a vaccine target antigen is based on not only the presence of the antigen in a variety of tumor tissues but also on the role this antigen plays in tumor growth and metastasis. These roles for TACAs are being elucidated. Newly acquired knowledge in understanding the T-independent immune response and in understanding the key roles that carbohydrates play in metastasis are being applied in attempts to develop an effective vaccine response to TACAs. The role of each of the above mentioned carbohydrate antigens in cancer growth and metastasis and vaccine attempts using these antigens will be described.

Monophosphoryl lipid A (MPL) as an adjuvant for anti-cancer vaccines: clinical results

As technological advances allow for the identification of tumor-associated antigens (TAAs) against which adaptive immune responses can be raised, efforts to develop vaccines for the treatment of cancer continue to gain momentum. Some of these vaccines target differentiation antigens that are expressed by tumors derived from one particular tissue (e. g., Melan-A/ MART-1, tyrosinase, gp 100). Some target antigens are specifically expressed in tumors of different types but not in normal tissues (e. g., MAGE-3), while other possible targets are antigens that are expressed at low level in normal tissues and are over-expressed in tumors of different types (e. g., HER2, Muc 1). Oncogenes (HER2/neu, Ras, E7 HPV 16), tumor suppressor genes (pS3) or tumor-specific post-translational modified proteins (under glycosylated Muc 1) can also be used as cancer vaccine candidates. In either case, these antigens tend to be poorly inmmunogenic by themselves and vaccines containing them generally require the inclusion of potent immunological adjuvants in order to generate robust anti-tumor immune responses in humans. Many adjuvants currently under evaluation for use in cancer vaccines activate relevant antigen presenting cells, such as dendritic cells and macrophages, via toll-like receptors (TLRs) and promote effective uptake, processing and presentation of antigen to T-cells in draining lymph nodes.Lipid A, the biologically active portion of the gram-negative bacterial cell wall constituent lipopolysaccharide (LPS), is known to possess strong immunostimulatory properties and has been evaluated for more than two decades as an adjuvant for promoting immune responses to minimally immunogenic antigens, including TAAs. The relatively recent discovery of TLRs and the identification of TLR4 as the signaling receptor for lipid A have allowed for a better understanding of how this immunostimulant functions with regard to induction of innate and adaptive immune responses.Although several lipid A species, including LPS and synthetic analogs, have been developed and tested as monotherapeutics for the treatment of cancer,1-8 only 3-O-desacyl-4'-monophosphoryl lipid A (MPL) has been evaluated as a cancer vaccine adjuvant in published human clinical trials. MPL comprises the lipid A portion of Salmonella minnesota LPS from which the (R)-3-hydroxytetrade canoyl group and the l-phosphare have been removed by successive acid and base hydrolysis.9 LPS and MPL induce similar cytokine profiles, but MPLis at least 1OO-fold less toxic.9,10 lOMPL has been administered to more than 300, 000 human subjects in studies of next-generation vaccines.11 In this chapter, published clinical trials conducted to evaluate the safety and/or efficacy of various cancer vaccines containing MPL, either alone or combined with other immunostimulants, Such as cell wall skeleton (CWS) of Mycobacterium phlei in the adjuvant Detox; Biomira, Inc.), the saponin QS-21 (in the adjuvants AS01B and AS02B; GSK Biologicals) or with QS-21 and CpG oligonucleotides (in the adjuvant AS15; GSK Biologicals) will be summarized. Combining MPL with other immunostimulants has been demonstrated to be advantageous in many cases and may be required to elicit the full complement of activities necessary to achieve an effective immune response and overcome the ability of tumors to evade attack by the immune system. In this chapter, information relating to vaccines targeting specific cancers will be presented in the first section, while information relating to vaccines targeting multiple tumor types by the induction of immune responses to shared TAAs is presented in the second section.

Synthetic and Immunological Studies of sTn Derivatives Carrying 5-N-(p-Substituted Phenylacetyl)Sialic Acid for the Development of Effective Cancer Vaccines

To search for effective cancer vaccines based on sTn, a sialylated tumor-associated carbohydrate antigen (sialo-TACA) expressed by a number of tumors, four unnatural N-acyl sTn derivatives, including 5'-N-p-methylphenylacetyl sTn (sTnNMePhAc), 5'-N-p-methoxylphenylacetyl sTn (sTnNMeOPhAc), 5'-N-p-acetylphenylacetyl sTn (sTnNAcPhAc) and 5'-N-p-chlorophenylacetyl sTn (sTnNClPhAc), as well as their protein conjugates, were synthesized by a highly convergent procedure. The immunological properties of these sTn derivatives in the form of keyhole limpet hemocyanin conjugate were evaluated in mice and compared to that of sTnNPhAc, a sTn derivative previously investigated as a vaccine candidate. It was shown that sTnNMePhAc, sTnNMeOPhAc, sTnNAcPhAc and sTnNClPhAc are all much more immunogenic than sTnNPhAc and that they provoked strong T cell-dependent IgG1 immune responses useful for cancer immunotherapy. It was concluded that sTnNClPhAc is a promising candidate for cancer vaccine development and is worthy further investigation.

Toll-like receptor agonists in cancer therapy

Toll-like receptors (TLRs) are pattern-recognition receptors related to the Drosophila Toll protein. TLR activation alerts the immune system to microbial products and initiates innate and adaptive immune responses. The naturally powerful immunostimulatory property of TLR agonists can be exploited for active immunotherapy against cancer. Antitumor activity has been demonstrated in several cancers, and TLR agonists are now undergoing extensive clinical investigation. This review discusses recent advances in the field and highlights potential opportunities for the clinical development of TLR agonists as single agent immunomodulators, vaccine adjuvants and in combination with conventional cancer therapies.

Immunizing against breast cancer: a new swing for an old sword

Therapeutic potential of vaccination has been explored in many clinical trials involving patients with breast cancer. A large variety of cancer immunogens have been tested. The majority of clinical vaccination studies have been carried out in patients with metastatic breast cancer, characterized by extremely aggressive malignant tumors, resistant to all standard cytotoxic treatments and with longest-lasting disease. With active specific immunotherapy, tumor-associated antigens coupled to appropriate adjuvant can elicit a powerful antitumor responses. The potential advantages of therapeutic cancer vaccines are that they can augment an established immunogenic response to the tumor (which is generally weak in breast cancer), they target specific tumor antigens (although there are few), they are potentially non-toxic, they can be combined with conventional therapies and/or other immunotherapies, and they elicit immunologic memory to prevent recurrence of the tumor. It is unclear whether therapeutic vaccines for cancer prolong survival. Data of clinical activity have been observed by using vaccines targeting HER-2/neu protein, human telomerase reverse transcriptase, carcinoembryonic antigen (CEA), and carbohydrate antigen given after stem cell rescue. A better understanding of the relation between innate and adaptive immune responses, and of the immune escape mechanisms employed by tumor cells, the discovery of mechanisms underlying immunological tolerance, and acknowledgment of the importance of both cell-mediated and humoral adaptive immunity for the control of tumour growth are necessary for leading to a more comprehensive immunotherapeutic approach in breast cancer.

Antigen-specific active immunotherapy for ovarian cancer

BACKGROUND

Despite advances in chemotherapy, prognosis of ovarian cancer remains poor. Antigen-specific active immunotherapy aims to induce a tumour-antigen-specific anti-tumour immune responses as an alternative treatment for ovarian cancer.

OBJECTIVES

To assess feasibility of antigen-specific active immunotherapy for ovarian cancer. Primary outcomes are clinical efficacy and antigen-specific immunogenicity with carrier-specific immunogenicity and side-effects as secondary outcomes.

SEARCH STRATEGY

A systematic search of the Cochrane Central Register of Controlled Trials (CENTRAL) Issue 3, 2009, Cochrane Gynaecological Cancer Group Specialized Register, MEDLINE and EMBASE databases and clinicaltrials.gov was performed (1966 to July 2009). Hand searches were conducted of the proceedings of relevant annual meetings (1996 to July 2009).

SELECTION CRITERIA

Randomised controlled trials (RCTs), as well as non-randomised non-controlled studies that included patients with epithelial ovarian cancer, irrespective of stage of disease, and treated with antigen-specific active immunotherapy, irrespective of type of vaccine, antigen used, adjuvant used, route of vaccination, schedule, and reported clinical or immunological outcomes.

DATA COLLECTION AND ANALYSIS

Data extraction was performed independently by two review authors. Risk of bias was evaluated with the Delphi-list for RCTs or a selection of quality domains pivotal to the assessment of non-RCTs and deemed best applicable to the non-randomised non-controlled studies.

MAIN RESULTS

Thirty-six studies were included. Response definitions showed substantial variation between trials, which makes comparison of trial results unreliable. Information on adverse events was frequently limited. Furthermore, reports of both RCTs and non-RCTs frequently lacked information necessary to assess risk of bias. Serious biases in these trials can thus not be ruled out.The largest body of evidence is currently available for CA-125 targeted antibody therapy (15 studies: 1505 patients). Non-RCTs of this CA-125 targeted antibody therapy suggest increased survival in humoral and/or cellular responders. However, three large randomised placebo-controlled trials did not show any clinical benefit despite induction of immune responses in approximately 60% of patients.Other small studies targeting many different tumour antigens showed promising immunological results. As these strategies have not yet been tested in RCTs, no reliable inferences about clinical efficacy can be made. Given the promising immunological results, limited side effects and toxicity exploration of clinical efficacy in large well-designed RCTs may be worthwhile.

AUTHORS' CONCLUSIONS

We conclude that despite promising immunological responses no clinically effective antigen-specific active immunotherapy is yet available for ovarian cancer. Furthermore, the adoption of guidelines to ensure uniformity in trial conduct, response definitions and trial reporting is recommended to improve quality and comparability of immunotherapy trials.

Tumor vaccines for breast cancer

The goal of cancer vaccines and immunotherapies is to train the immune system to recognize cancer cells and destroy them. Immune responses play a dynamic role in the development of cancers, from immunosurveillance to immune escape; from in situ immune dysregulation to metastatic spread. The systematic identification and targeting of molecules involved in the immune response has led to a wide variety of potential immunotherapeutic targets for the treatment of breast cancer. Extraordinary advances in molecular immunology have led to a detailed understanding of tumor antigens, antigen presentation, innate immunity, cytokine and chemokine pathways, and immunoregulation. Many of these vaccine therapies are already in clinical development. It is the rational and rapid translation of these scientific discoveries into effective therapies for patients with breast cancer that poses the greatest challenge, and opportunity, to realize the potential of tumor vaccine therapy for breast cancer.

Mucin-type O-glycosylation and its potential use in drug and vaccine development

Mucin-type O-glycans are found on mucins as well as many other glycoproteins. The initiation step in synthesis is catalyzed by a large family of polypeptide GalNAc-transferases attaching the first carbohydrate residue, GalNAc, to selected serine and threonine residues in proteins. During the last decade an increasing number of GalNAc-transferase isoforms have been cloned and their substrate-specificities partly characterized. These differences in substrate specificities have been exploited for in vitro site-directed O-glycosylation. In GlycoPEGylation, polyehylene glycol (PEG) is transferred to recombinant therapeutics to specific acceptor sites directed by GalNAc-transferases. GalNAc-transferases have also been used to control density of glycosylation in the development of glycopeptide-based cancer vaccines. The membrane-associated mucin-1 (MUC1) has long been considered a target for immunotherapeutic and immunodiagnostic measures, since it is highly overexpressed and aberrantly O-glycosylated in most adenocarcinomas, including breast, ovarian, and pancreatic cancers. By using vaccines mimicking the glycosylation pattern of cancer-cells, it is possible to overcome tolerance in transgenic animals expressing the human MUC1 protein as a self-antigen providing important clues for an improved MUC1 vaccine design. The present review will highlight some of the potential applications of site-directed O-glycosylation.

Lessons from randomized phase III studies with active cancer immunotherapies--outcomes from the 2006 meeting of the Cancer Vaccine Consortium (CVC)

After years of effort to develop active cancer immunotherapies, seven candidate products achieved promising results in phase I/II studies that triggered phase III randomized studies. One candidate to date has received an approvable letter from the United States Food and Drug Administration (FDA), defining a clear path to licensure for sipuleucel-T (Provenge, Dendreon) within the next couple of years. The other phase III studies failed to achieve statistical criteria for some or all of the critical endpoints. Yet, there is widespread recognition that using a patient's own immune system to target and destroy cancer cells may offer an effective biological therapy with less toxicity than presently available anti-cancer therapies, and several candidates are still being evaluated in clinical studies. This review summarizes the lessons learned from these case studies, evaluates scientific, study design, and business factors that can affect study outcomes, identifies common challenges faced by sponsors developing these innovative therapies, and provides considerations for future study designs that may increase the likelihood of success.

Efficient glycoengineering of GM3 on melanoma cell and monoclonal antibody-mediated selective killing of the glycoengineered cancer cell

To verify the principal of a new immunotherapeutic strategy for cancer, a monoclonal antibody 2H3 against N-phenylacetyl GM3, an unnatural form of the tumor-associated antigen GM3, was prepared and employed to demonstrate that murine melanoma cell B16F0 could be effectively glycoengineered by N-phenylacetyl-d-mannosamine to express N-phenylacetyl GM3 and that 2H3 was highly cytotoxic to the glycoengineered B16F0 cell in the presence of complements. It was further demonstrated that B16F0 cell could be glycoengineered 4-5 times more effectively than 3T3 A31 cell, a normal murine embryo fibroblast cell, and that the antibody and complement mediated cytotoxicity was at least 200 times more potent to the glycoengineered B16F0 cell than to the N-phenylacetyl-d-mannosamine-treated 3T3 A31 cell. These results show the promise for developing useful melanoma immunotherapies based on vaccination against N-phenylacetyl GM3 followed by treatment with N-phenylacetyl-d-mannosamine.

Immunology and breast cancer: therapeutic cancer vaccines

Cancer immunosurveillance is a process that results from activity of recognition and destruction of cancer cells by innate and adaptive immune effector cells and molecules. Cancer cells can avoid immunosurveillance through the immunoselection, that is the development of poorly immunogenic tumor-cell variants, and through subversion of the immune system (also known as immunosubversion). Identification of tumor antigens (Ags) that can be recognized by immune effector cells has opened the perspective of developing therapeutic vaccines in the field of breast cancer. Breast cancer vaccines can induce immunogenic response against tumors weakly immunogenic; usually have a good tolerance and safety profile and can induce a long-term immune memory, critical to prevent efficiently tumor recurrence. Several studies evaluating breast cancer vaccines have been performed in patients with extended metastatic breast cancer, usually refractory to other standard treatments so that clinical efficacy was difficult to achieve. Significant immune responses against tumor Ags induced upon vaccinations were described to several tumor Ag vaccines. A better understanding of the relation between innate and adaptive immune responses, of the immune escape mechanisms employed by tumor cells and acknowledgment of the importance of both cell-mediated and humoral adaptive immunity for the control of tumor growth are necessary for leading to a more comprehensive immunotherapeutic approach in breast cancer.

Inhibition of spontaneous breast cancer metastasis by anti-Thomsen-Friedenreich antigen monoclonal antibody JAA-F11

Thomsen-Friedenreich antigen (TF-Ag) is expressed in many carcinomas, including those of the breast, colon, bladder, and prostate. TF-Ag is important in adhesion and metastasis and as a potential immunotherapy target. We hypothesized that passive transfer of JAA-F11, an anti-TF-Ag monoclonal antibody, may create a survival advantage for patients with TF-Ag-expressing tumors by cytotoxicity, blocking of tumor cell adhesion, and inhibition of metastasis. This was tested using in vitro models of tumor cell growth; cytotoxicity assays; in vitro, ex vivo, and in vivo models of cancer metastasis; and, finally, in vivo effects in mice with metastatic breast cancer. Unlike some anti-TF-Ag antibodies, JAA-F11 did not enhance breast carcinoma cell growth. JAA-F11 did not induce the killing of 4T1 tumor cells through complement-dependent cytotoxicity or apoptotic mechanisms. However, JAA-F11 blocked the stages of metastasis that involve the adhesion of human breast carcinoma cells to human endothelial cells (human umbilical vein endothelial cells and human bone marrow endothelial cells 60) in in vitro static adhesion models, in a perfused ex vivo model, and in murine lung vasculature in an in vivo metastatic deposit formation assay. JAA-F11 significantly extended the median survival time of animals bearing metastatic 4T1 breast tumors and caused a > 50% inhibition of lung metastasis.

Vaccination with Theratope (STn-KLH) as treatment for breast cancer

Cancer vaccines have demonstrated that they can stimulate antibody and cell-mediated immune responses against tumor-associated antigens in the laboratory. However, few clinical studies with cancer vaccines have demonstrated convincing clinical responses. Sialyl-Tn is a carbohydrate associated with MUC1. It is a unique tumor-associated antigen, present on many adenocarcinomas including breast, ovarian, colorectal, gastric and pancreatic. Consequently, Sialyl-TN is an ideal candidate for boosting the patient's immune system specifically against a unique tumor-associated antigen. The cancer vaccine Theratope was developed by Biomira, Inc. using a synthetic Sialyl-Tn antigen that emulates the unique carbohydrate on human cancer. Clinical trials have predominantly been carried out in breast cancer patients and these trials are outlined in this profile.

Improving the antigenicity of sTn antigen by modification of its sialic acid residue for development of glycoconjugate cancer vaccines

Sialyl Tn (sTn) antigen is a sialylated disaccharide abundantly expressed by many tumors. To search for effective cancer immunotherapies based on sTn antigen, we designed and synthesized a series of unnatural N-acyl derivatives of sTn and studied their immunological properties. For this purpose, an efficient method was developed to synthesize the natural and unnatural forms of sTn antigen and their protein conjugates. The resultant glycoconjugates were used to immunize C57BL/6 mice, and the immune response was assessed by enzyme-linked immunosorbent assay (ELISA). Whereas the keyhole limpet hemocyanin (KLH) conjugate of sTn elicited low levels of IgM antibodies, the KLH conjugates of N-iso-butanoyl sTn and N-phenylacetyl sTn, especially the latter, induced high titers of antigen-specific IgG antibodies, showing a T-cell-dependent response that is critical for the antitumor activity. The results suggest that the modified forms of sTn, especially N-phenylacetyl sTn, have improved antigenicity and promising immunological properties for use as cancer vaccines.

Biological significance of cancer-associated sialyl-Tn antigen: modulation of malignant phenotype in gastric carcinoma cells

The activation of an abnormal glycosylation pathway in cancer cells leads to the formation of the sialyl-Tn antigen, blocking regular carbohydrate chain elongation. Sialyl-Tn antigen is rarely expressed in normal tissues but is aberrantly expressed in a variety of carcinomas, where it constitutes a marker of poor prognosis. Although the clinical significance of sialyl-Tn is well characterized, a functional role for this glycan and its contribution to cancer progression remain to be elucidated. This study evaluates the capability of sialyl-Tn to modify processes like cell cycle, apoptosis, actin cytoskeleton dynamics, adhesion and motility on ECM components, cell-cell aggregation and invasion. De-novo expression of sialyl-Tn leads to major morphological and cell behavior alterations in gastric carcinoma cells which were reverted by specific antibody blockage. Sialyl-Tn antigen is able to modulate a malignant phenotype inducing a more aggressive cell behavior, such as decreased cell-cell aggregation and increased ECM adhesion, migration and invasion.

Carbohydrate based vaccines

In the past decades, a gradual increase in the resistance to antibiotics has been observed, leading to a serious thread for successful treatment of bacterial infections. This feature in addition to difficulties in developing adequate drugs against (tropical) diseases caused by parasites has stimulated the interest in vaccines to prevent infections. In principle, various types of cell surface epitopes, characteristic for the invading organism or related to aberrant growth of cells, can be applied to develop vaccines. The progress in establishing the structure of carbohydrate immuno-determinants in conjunction with improvements in carbohydrate synthesis has rendered it feasible to develop new generations of carbohydrate-based vaccines.

Efficient metabolic engineering of GM3 on tumor cells by N-phenylacetyl-D-mannosamine

Abnormal carbohydrates expressed on tumor cells, which are termed tumor-associated carbohydrate antigens (TACAs), are potential targets for the development of cancer vaccines. However, immune tolerance to TACAs has severely hindered progress in this area. To overcome this problem, we have developed a novel immunotherapeutic strategy based on synthetic cancer vaccines and metabolic engineering of TACAs on tumor cells. One critical step of this new strategy is metabolic engineering of cancer, namely, to induce expression of an artificial form of a TACA by supplying tumors with an artificial monosaccharide precursor. To identify the proper precursor for this application, N-propionyl, N-butanoyl, N-isobutanoyl, and N-phenylacetyl derivatives of d-mannosamine were synthesized, and their efficiency as biosynthetic precursors in modifying sialic acid and inducing expression of modified forms of GM3 antigen on tumor cells was investigated. For this purpose, tumor cells were incubated with different N-acyl-d-mannosamines, and modified forms of GM3 expressed on tumor cells were analyzed by flow cytometry using antigen-specific antisera. N-Phenylacetyl-d-mannosamine was efficiently incorporated in a time- and dose-dependent manner to bioengineer GM3 expression by several tumor cell lines, including K562, SKMEL-28, and B16-F0. Moreover, these tumor cell lines also exhibited ManPAc-dependent sensitivity to cytotoxicity mediated by anti-PAcGM3 immune serum and complement. These results provide an important validation for this novel therapeutic strategy. Because N-phenylacetyl GM3-protein conjugates are particularly immunogenic, the combination of an N-phenylacetyl GM3 conjugate vaccine with systemic N-phenylacetyl-d-mannosamine treatment is a promising immunotherapy for future development and application to melanoma and other GM3-bearing tumors.

Immunity for tumors and microbes after autotransplantation: if you build it, they will (not) come

Relapses after autologous stem cell transplants for hematopoietic malignancies are frequent and post-transplant infections continue to cause significant post-transplant morbidity and even mortality. The post-transplant period is typically characterized by low lymphocyte counts and impaired immune cell function. Early restoration of immune function may contribute to better disease control and enhance protection from infections. Indeed the attainment of a 'minimal residual disease' status following high-dose therapy makes the early post-transplant period ideal for the introduction of antitumor immunotherapy. Attempts to generate immunity against tumor and microbial antigens after autotransplantation have included vaccinations, T cell infusions (both resting and activated) and combinations of vaccinations and adoptive T cell infusions. One successful strategy for generating robust immune responses against microbial antigens was the combination of pre and post-transplant immunizations along with an early (post-transplant) infusion of in vivo vaccine-primed and ex vivo co-stimulated autologous T cells. Whether this or similar strategies will lead to the generation of effective antitumor immunity is unknown. The lessons gained from efforts to rebuild immune system function in the setting of autotransplantation may also be applicable to the problem of restoring immunity in other immunodeficient groups such as patients with cancer or HIV disease and the elderly.

Immunotherapy for gynaecological malignancies

Gynaecological malignancies, excluding breast cancer, cause approximately 25,000 deaths yearly among women in the US. Therefore, novel approaches for the prevention or treatment of these diseases are urgently required. In the case of cervical cancer, human papillomavirus (HPV) xenoantigens are readily recognised by the immune system, and their targeting has shown great promise in preclinical models of therapeutic vaccination and in clinical studies of preventative vaccination. A growing body of evidence indicates that ovarian cancer is also immunogenic and can thus be targeted through immunotherapy. This review outlines the principles and problems of immunotherapy for cervical and ovarian cancer, including the authors' personal assessment.

Breast cancer vaccines: a clinical reality or fairy tale?

The characterization of tumor antigens recognized by immune effector cells has opened the perspective of developing therapeutic vaccines in the field of breast cancer. The potential advantages of the vaccines are: (i) the induction of a robust immune response against tumors that are spontaneously weekly immunogenic; (ii) the tumor specificity for some antigens; (iii) the good tolerance and safety profile and (iv) the long-term immune memory, critical to prevent efficiently tumor recurrence. Most trials evaluating breast cancer vaccines have been carried out in patients with extended metastatic breast cancer, characterized by aggressive tumors, resistant to standard cytotoxic treatments, so that clinical efficacy was difficult to achieve. However, some significant immune responses against tumor antigens induced upon vaccinations were recorded. The aim of this review is to analyze the activity of vaccination strategies in current clinical trials. Data of clinical activity have been observed by using vaccines targeting HER2/neu protein, human telomerase reverse transcriptase, carcinoembryonic antigen and carbohydrate antigen given after stem cell rescue. The review discusses possible future directions for vaccine development and applications in the adjuvant setting.

Development of a CTL vaccine for Her-2/neu using peptide-microspheres and adjuvants

With the ultimate goal of developing a therapeutic cancer vaccine, we encapsulated the Her-2/neu peptide p369-377 in poly(lactide-co-glycolide) microspheres. This formulation was found to effectively elicit CD8+ cytotoxic T cell (CTL) responses in an HLA-A*0201 transgenic mouse model. In contrast, immunization with either peptide alone or peptide formulated in incomplete Freund's adjuvant (IFA) failed to elicit such CTL responses. Responses induced by the peptide-microsphere formulation were found to peak at approximately 6 weeks post-immunization, and were enhanced by delivering increased doses of peptide and with repeated administrations over time. Co-administration of the peptide-microspheres with adjuvants, including granulocyte-macrophage colony stimulating factor, MPL adjuvant and select synthetic Toll-Like Receptor 4 ligands, the aminoalkyl glucosaminide-4 phosphates, significantly augmented CTL responses. These studies provide important guidance for the design of human clinical trials of microsphere vaccines in terms of optimal peptide-microsphere formulation, vaccination regimen, vaccine dose, and adjuvant selection.

Therapeutic potential of a tumor-specific, MHC-unrestricted T-cell receptor expressed on effector cells of the innate and the adaptive immune system through bone marrow transduction and immune reconstitution

T-cell receptor (TCR) with unique major histocompatibility complex (MHC)-unrestricted antigen-binding properties was isolated from a human T-cell clone specific for the tumor antigen MUC1. This TCR binds its epitope on the MUC1 protein without the requirement of processing and presentation. A single-chain Valpha/Vbeta/Cbeta (scTCR) was fused to a CD3 zeta (zeta) chain to allow expression on the surface of cells of the innate (granulocytes, macrophages, natural killer [NK] cells) as well as the adaptive (T and B cells) immune system. To test the ability of the cells of the innate immune system to reject a tumor when provided with a tumor antigen-specific TCR, we reconstituted severe combined immunodeficiency (SCID) mice with bone marrow cells transduced with a retroviral vector encoding this receptor and challenged them with a MUC1-positive human tumor. These mice controlled the growth of the tumor significantly better than the control mice. We performed a similar experiment in immunocompetent mice transgenic for human MUC1. Expression of the TCR on large percentages of cells did not result in infiltration or destruction of tissues expressing MUC1. Reconstituted mice controlled the outgrowth of a MUC1-transfected but not the parental control tumor. scTCR expression appears lifelong, suggesting a successful transduction of the self-renewing stem cells.

Role of the human ST6GalNAc-I and ST6GalNAc-II in the synthesis of the cancer-associated sialyl-Tn antigen

The Sialyl-Tn antigen (Neu5Acalpha2-6GalNAc-O-Ser/Thr) is highly expressed in several human carcinomas and is associated with carcinoma aggressiveness and poor prognosis. We characterized two human sialyltransferases, CMP-Neu5Ac:GalNAc-R alpha2,6-sialyltransferase (ST6GalNAc)-I and ST6GalNAc-II, that are candidate enzymes for Sialyl-Tn synthases. We expressed soluble recombinant hST6GalNAc-I and hST6GalNAc-II and characterized the substrate specificity of both enzymes toward a panel of glycopeptides, glycoproteins, and other synthetic glycoconjugates. The recombinant ST6GalNAc-I and ST6GalNAc-II showed similar substrate specificity toward glycoproteins and GalNAcalpha-O-Ser/Thr glycopeptides, such as glycopeptides derived from the MUC2 mucin and the HIVgp120. We also observed that the amino acid sequence of the acceptor glycopeptide contributes to the in vitro substrate specificity of both enzymes. We additionally established a gastric cell line, MKN45, stably transfected with the full length of either ST6GalNAc-I or ST6GalNAc-II and evaluated the carbohydrate antigens expression profile induced by each enzyme. MKN45 transfected with ST6GalNAc-I showed high expression of Sialyl-Tn, whereas MKN45 transfected with ST6GalNAc-II showed the biosynthesis of the Sialyl-6T structure [Galbeta1-3 (Neu5Acalpha2-6)GalNAc-O-Ser/Thr]. In conclusion, although both enzymes show similar in vitro activities when Tn antigen alone is available, whenever both Tn and T antigens are present, ST6GalNAc-I acts preferentially on Tn antigen, whereas the ST6GalNAc-II acts preferentially on T antigen. Our results show that ST6GalNAc-I is the major Sialyl-Tn synthase and strongly support the hypothesis that the expression of the Sialyl-Tn antigen in cancer cells is due to ST6GalNAc-I activity.

Therapeutic cancer vaccines: an emerging treatment option

Therapeutic cancer vaccines treat disease by stimulating the body's immune system. They are a form of active immunotherapy with the goal of producing an immune response that involves the cellular and humoral components of the immune system. These two components appear to be complementary and work together to induce tumor regression and long-lasting immunity to the disease being treated. This article reviews the history of cancer vaccine development, autologous and allogeneic vaccines, vaccine targets, carrier proteins, adjuvants, and clinical trial data of studies evaluating cancer vaccines. Knowledge of this emerging cancer treatment option will enable oncology nurses to be informed about cancer vaccines and accurately provide information about them to patients.

Immunologic principles and immunotherapeutic approaches in ovarian cancer

Ovarian cancer is an immunogenic tumor, and numerous antigens have been identified in recent years. Several of these antigens are important in regulating tumor growth and may be ideal targets for the development of immune-based strategies. In the absence of immunologic intervention, tumors evade the immune system by several mechanisms, most notably tolerance and immunosuppression. As understanding of the immune response improves, strategies are being designed to circumvent T-cell tolerance to self-antigens through modulation of APC function. In addition, techniques are being developed to identify reverse ovarian cancer-induced immune evasion tactics. The type of the immune-based therapy to apply varies with disease burden. It is hoped that discoveries at the bench along with lessons learned in prior clinical trials soon will allow clinicians to develop rationally based immunologic strategies to treat and prevent ovarian cancer.

Clinical development of the STn-KLH vaccine (Theratope)

The development of active specific immunotherapy depends on the identification of altered cancer cell-specific molecules or epitopes that are immunogenic. Many cancer-specific peptide or glycoprotein target antigens have been identified. Tumors carrying aberrant epitopes as a result of underglycosylation of mucins are associated with poor prognosis in many epithelial cancers. The aberrant mucin sialyl-Tn (STn) epitope, in addition to being a predictor of poor prognosis when expressed in tumors, is associated with increased aggressiveness and metastatic potential, making it a promising target for immunotherapy. The STn-keyhole limpet hemocyanin (KLH) vaccine (Theratope) is an investigational active specific immunotherapy consisting of a synthetic STn epitope conjugated to a high molecular weight protein carrier, KLH. The immune response generated by the STn-KLH vaccine is both humoral and cellular. More than 1000 breast cancer patients with metastatic disease are currently enrolled in a phase III clinical trial to assess the safety and efficacy of the STn-KLH vaccine. Interim analysis from a current phase III trial has confirmed the safety of the STn-KLH vaccine, and the clinical outcome awaits the final analysis expected in 2003.

Rationale for the clinical development of STn-KLH (Theratope) and anti-MUC-1 vaccines in breast cancer

Mucin-1 (MUC-1) is a high-molecular-weight glycoprotein rich in serine and threonine residues that are O-glycosylated. Expression of MUC-1 is increased in breast, ovarian, and other adenocarcinomas, and altered glycosylation results in exposure of novel peptide epitopes and the expression of tumor-associated carbohydrate residues, such as Thomsen-Freidenreich and sialyl-Tn (STn) antigens. Preclinical studies suggested that induction of immune response to tumor-associated carbohydrate moieties results in inhibition of tumor growth. A synthetic STn-keyhole limpet hemocyanin (KLH) vaccine (Theratope) is currently being evaluated in clinical trials as active specific immunotherapy in the treatment of advanced breast cancer. Two phase II trials in 50 breast cancer patients compared the STn-KLH vaccine with and without a single low-dose infusion of cyclophosphamide used as an immunomodulator prior to initiation of treatment. Humoral immune responses were higher in patients who had received low-dose cyclophosphamide intravenously (I.V.) compared with patients who had received no cyclophosphamide or oral cyclophosphamide. There was a statistically significant survival difference between all patients treated with the STn-KLH vaccine (overall median survival, 19.1 months; n = 50) and the retrospective control patients (overall median survival, 9.2 months; n = 104). Furthermore, patients who received cyclophosphamide I.V. prior to the STn-KLH vaccine had median survival rates close to 3 times that of patients in a retrospective, frequency-matched, control group who received conventional therapies (cyclophosphamide-I.V. group, 26.5 months vs. 9.2 months, control group). The trials reported minimal toxicity profile with local reactions in the injection site and some flu-like symptoms. On the basis of the phase II trial results, a phase III clinical trial of the STn-KLH vaccine is underway. The trial was closed to enrollment in March 2001 with the accrual of 1030 women. The final analysis is event driven and is expected to commence mid 2003.

Use of the anti-idiotype breast cancer vaccine 11D10 in conjunction with autologous stem cell transplantation in patients with metastatic breast cancer

The results of cytotoxic therapy, including dose-intensive therapy requiring autologous stem cell transplantation (ASCT), have been disappointing in patients with metastatic breast cancer, as almost all patients eventually experience disease progression. There has been a renewed interest in immunotherapeutic strategies in this disease, including evaluation of several breast cancer vaccines. In the current study, we describe the results of a program in which the anti-idiotype breast cancer vaccine 11D10 (TriAb) was administered before and after ASCT in patients with metastatic breast cancer chemosensitive to previous conventional therapy. The toxicity of this approach was acceptable, and idiotype-specific humoral and T-cell proliferative responses were observed in the majority of patients within a few weeks post-ASCT. The actuarial 3-year overall survival rate was 48% (95% CI, 32%-64%), while the progression-free survival rate was 32% (95% CI, 19%-45%). Multivariate analysis identified achievement of a strong antibody and cellular immune response to the vaccine as the only significant prognostic factors for outcome. The ability to reliably produce robust immune responses after ASCT is encouraging. Further studies are required to determine if the immune response mediates an antitumor benefit in these patients.

The role of cancer vaccines following autologous stem cell rescue in breast and ovarian cancer patients: experience with the STn-KLH vaccine (Theratope)

The success of high-dose chemotherapy followed by autologous stem-cell rescue as treatment for breast and ovarian cancer is limited by a high incidence of relapse. After autologous transplantation, patients are likely to have a low tumor burden and thus would be more likely to respond immunologically to a cancer vaccine. Sialyl-Tn (STn) is a carbohydrate associated with the MUC1 mucin on breast and ovarian cancer and is an ideal candidate for vaccine immunotherapy. Sialyl-Tn-keyhole limpet hemocyanin (STn-KLH) vaccine (Theratope) incorporates a synthetic STn antigen that mimics the unique tumor-associated STn carbohydrate and is designed to stimulate tumor antigen-specific immune responses in patients with mucin-expressing tumors. Between 1995 and 2000, 70 patients (16 with stage II/III breast cancer, 17 with stage III/IV ovarian cancer, and 37 with stage IV breast cancer) were treated with 2 different formulations of STn-KLH. Toxicity, outcome, and immune response data are reported. STn-KLH was well-tolerated with minimal toxicity. The most common side effects were indurations and erythema at the sites of injections. Humoral and cellular responses were elicited in the majority of patients. Overall, these data indicate that post-autologous transplant patients are able to mount an effective immune response to vaccine immunotherapy with minimal side effects, and that vaccine immunotherapy may be a useful addition to high-dose chemotherapy regimens.

Mechanisms of the antitumoral effect of lipid A

Bacterial lipopolysaccharide (LPS) and its active component, lipid A, have been used either alone or as adjuvant in therapeutic anticancer vaccines. Lipid A induces various transcription factors via intracellular signaling cascades initiated by their receptor CD14-TLR4. These events lead to the synthesis of cytokines, which either have direct cytotoxic effect or stimulate the immune system. Their antitumoral effect has been demonstrated in animal models as well as clinical trials. Studies in animal models showed that their antitumoral effect relies mostly on the generation of an effective immune response. In humans, the antitumoral effect was correlated with an antibody response and cell-mediated cytotoxicity. So far, some encouraging results have been achieved in phase I and II clinical trials with regards to response and stabilization of the disease, but an expansion of the studies and trials is needed to find the best conditions for their clinical application.

Second-line and subsequent therapy for ovarian carcinoma

Ovarian carcinoma continues to be the leading cause of death among gynecologic malignancies. Paclitaxel and platinum chemotherapy is still the treatment of choice after primary debulking surgery. Salvage chemotherapy with several single agents has only modest activity and does not prolong survival of patients with relapsed ovarian carcinoma. An intense search has been made for novel approaches to treatment of ovarian cancer, and several new treatments, such as immunotherapy and gene therapy, show promise. Newer combination chemotherapy regimens and molecularly targeted therapy need to be developed. High-dose chemotherapy with autologous stem-cell transplantation appears to benefit selected groups of patients and is still investigational. Whole abdominal radiotherapy for relapsed microscopic disease should be studied in prospective randomized trials. Women with advanced ovarian carcinoma should continue to be encouraged to participate in well-designed clinical trials.

Chemoenzymatic synthesis of sialylated glycopeptides derived from mucins and T-cell stimulating peptides

The Tn, T, sialyl-Tn, and 2,3-sialyl-T antigens are tumor-associated carbohydrate antigens expressed on mucins in epithelial cancers, such as those affecting the breast, ovary, stomach, and colon. Glycopeptides carrying these antigens are of interest for development of cancer vaccines and a short, chemoenzymatic strategy for their synthesis is reported. Building blocks corresponding to the Tn (GalNAc alpha-Ser/Thr) and T [Gal beta(1-->3)GalNAc alpha-Ser/Thr] antigens, which are relatively easy to obtain by chemical synthesis, were prepared and then used in the synthesis of glycopeptides on the solid phase. Introduction of sialic acid to give the sialyl-Tn [Neu5Ac alpha(2-->6)GalNAc alpha-Ser/Thr] and 2,3-sialyl-T [Neu5Ac alpha(2-->3)Gal beta(1-->3)GalNAc alpha-Ser/Thr] antigens is difficult when performed chemically at the building block level. Sialylation was therefore carried out with recombinant sialyltransferases in solution after cleavage of the Tn and T glycopeptides from the solid phase. In the same manner, the core 2 trisaccharide [Gal beta 1-->3(GlcNAc beta 1-->6)GalNAc] was incorporated in glycopeptides containing the T antigen by using a recombinant N-acetylglucosaminyltransferase. The outlined chemoenzymatic approach was applied to glycopeptides from the tandem repeat domain of the mucin MUC1, as well as to neoglycosylated derivatives of a T cell stimulating viral peptide.

Blood stem cell transplantation for breast cancer: new approaches using pre- peri- post-transplant immunotherapy

Autologous peripheral blood stem cell transplantation (auto-PBSCT) after high dose chemotherapy is usually offered to breast cancer patients carrying a high risk of relapse or having chemosensitive metastatic disease. Whether progression free and overall survival of such patients is improved after auto-PBSCT compared to conventional chemotherapy is a matter of debate. Currently available results of randomised trials could not uniformly prove or disprove auto-PBSCT being advantageous. Yet such studies have not employed any manipulation of the stem cell graft or any post-transplant immunomodulation exploiting the unique immunological environment for tumour eradication which exists only after auto-PBSCT. Preliminary data have discussed the ex vivo and in vivo generation of cytotoxic effector cells employing IL-2 and/or IFN-alpha/gamma in the auto-PBSCT setting. Other cytokines such as IL-12, IL-15 and prolactin have likewise been considered. Several anticancer vaccine protocols after auto-PBSCT are ongoing using monovalent vaccines or anti-idiotypic antibodies. Polyvalent anticancer vaccines, cytokine secreting tumour cells, tumour pulsed or hybridised dendritic cells (DC) enhanced with cytokines are studied. Monoclonal antibodies (mAb) could assist: unlabelled for pretransplant exvivo purging, post-transplant for enhancing antibody-dependent cell mediated cytotoxicity (ADCC) or radioimmunoconjugated as an additive cytotoxic part of the conditioning regimen. Autologous graft versus host induction and allogeneic stem cell transplantation (probably with non-myeloablative conditioning followed by donor lymphocyte infusions) are other approaches. Evaluation of successful combinations, optimal dosages and appropriate timing schedules is the subject of future investigations. Since breast cancer patients belong to countless subgroups, a large number of protocols need to be addressed in order to avoid over treatment and prevent relapse.