Immunogenicity of melanoma-associated gangliosides in cancer patients

Anti-glycan antibodies: roles in human disease

Carbohydrate-binding antibodies play diverse and critical roles in human health. Endogenous carbohydrate-binding antibodies that recognize bacterial, fungal, and other microbial carbohydrates prevent systemic infections and help maintain microbiome homeostasis. Anti-glycan antibodies can have both beneficial and detrimental effects. For example, alloantibodies to ABO blood group carbohydrates can help reduce the spread of some infectious diseases, but they also impose limitations for blood transfusions. Antibodies that recognize self-glycans can contribute to autoimmune diseases, such as Guillain-Barre syndrome. In addition to endogenous antibodies that arise through natural processes, a variety of vaccines induce anti-glycan antibodies as a primary mechanism of protection. Some examples of approved carbohydrate-based vaccines that have had a major impact on human health are against pneumococcus, Haemophilus influeanza type b, and Neisseria meningitidis. Monoclonal antibodies specifically targeting pathogen associated or tumor associated carbohydrate antigens (TACAs) are used clinically for both diagnostic and therapeutic purposes. This review aims to highlight some of the well-studied and critically important applications of anti-carbohydrate antibodies.

Upregulation of cell surface GD3 ganglioside phenotype is associated with human melanoma brain metastasis

Melanoma metastasis to the brain is one of the most frequent extracranial brain tumors. Cell surface gangliosides are elevated in melanoma metastasis; however, the metabolic regulatory mechanisms that govern these specific changes are poorly understood in melanoma particularly brain metastases (MBM) development. We found ganglioside GD3 levels significantly upregulated in MBM compared to lymph node metastasis (LNM) but not for other melanoma gangliosides. Moreover, we demonstrated an upregulation of ST8SIA1 (GD3 synthase) as melanoma progresses from melanocytes to MBM cells. Using RNA‐ISH on FFPE specimens, we evaluated ST8SIA1 expression in primary melanomas (PRM) (n = 23), LNM and visceral metastasis (n = 45), and MBM (n = 39). ST8SIA1 was significantly enhanced in MBM compared to all other specimens. ST8SIA1 expression was assessed in clinically well‐annotated melanoma patients from multicenters with AJCC stage III B‐D LNM (n = 58) with 14‐year follow‐up. High ST8SIA1 expression was significantly associated with poor overall survival (HR = 3.24; 95% CI, 1.19–8.86, P = 0.02). In a nude mouse human xenograft melanoma brain metastasis model, MBM variants had higher ST8SIA1 expression than their respective cutaneous melanoma variants. Elevated ST8SIA1 expression enhances levels of cell surface GD3, a phenotype that favors MBM development, hence associated with very poor prognosis. Functional assays demonstrated that ST8SIA1 overexpression enhanced cell proliferation and colony formation, whereby ST8SIA1 knockdown had opposite effects. Icaritin a plant‐derived phytoestrogen treatment significantly inhibited cell growth in high GD3‐positive MBM cells through targeting the canonical NFκB pathway. The study demonstrates GD3 phenotype associates with melanoma progression and poor outcome.

Gangliosides generalities and role in cancer therapies

Gangliosides are located in the plasma membrane; this confers them the ability to interact with other molecules in order to participate in important cellular processes. Some gangliosides presence or absence in the cell surface is associated with either normal condition or pathologies. Particularly in cancer, gangliosides play a critical role in pathological events like cellular malignancy, tumor formation, and metastasis, defining gangliosides as good candidates to be used as cellular markers. When specific gangliosides are exhibited, immunotherapy could be applied in order to inhibit tumorigenesis or induce an immunogenic response. Novel cancer treatments such as NGcGM3/VSSP vaccines, valproic acid, BMS-345541 inhibitor of GD2 and immunotherapies using 1E10 and 14F7 monoclonal antibodies are described. On this review, there will be studied the gangliosides that allowed developing biological techniques that can give immunogenicity to cancer cells

GM3(Neu5Gc) ganglioside: an evolution fixed neoantigen for cancer immunotherapy

Numerous molecules have been considered as targets for cancer immunotherapy because of their levels of expression on tumor cells, their putative importance for tumor biology, and relative immunogenicity. In this review we focus on the ganglioside GM3(Neu5Gc), a glycosphingolipid present on the outer side of the plasma membrane of vertebrate cells. The reasons for selecting GM3(Neu5Gc) as a tumor-specific antigen and its use as a target for cancer immunotherapy are discussed, together with the development of antitumor therapies focused on this target by the Center of Molecular Immunology (CIM, Cuba).

Whole-Cell Cancer Vaccines Induce Large Antibody Responses to Carbohydrates and Glycoproteins

Whole-cell cancer vaccines are a promising strategy for treating cancer, but the characteristics of a favorable immune response are not fully understood. New insights could enable development of better vaccines, discovery of new antigens, and identification of biomarkers of efficacy. Using glyco-antigen microarrays, we demonstrate that GVAX Pancreas (a granulocyte macrophage colony-stimulating factor-modified whole-cell tumor vaccine) induces large immunoglobulin G and immunoglobulin M responses to many antigens, including tumor-associated carbohydrates, blood group antigens, α-Gal, and bovine fetuin. Antibody responses to α-Gal, a glycan found in fetal bovine serum (FBS) used to produce the vaccine, correlated inversely with overall survival and appear to compete with productive responses to the vaccine. H1299 lysate vaccine, produced with FBS, also induced responses to α-Gal and fetuin but not K562-GM, which is produced in serum-free medium. Our results provide new potential biomarkers to evaluate productive/unproductive immune responses and suggest that removal/reduction of FBS could improve the efficacy of whole-cell vaccines.

Immunotherapy for advanced melanoma: future directions

As calculated by the meta-analysis of Korn et al., the prognosis of metastatic melanoma in the pretarget and immunological therapy era was poor, with a median survival of 6.2 and a 1-year life expectancy of 25.5%. Nowadays, significant advances in melanoma treatment have been gained, and immunotherapy is one of the promising approaches to get to durable responses and survival improvement. The aim of the present review is to highlight the recent innovations in melanoma immunotherapy and to propose a critical perspective of the future directions of this enthralling oncology subspecialty.

Development of a novel methodology for cryopreservation of melanoma cells applied to CSF470 therapeutic vaccine

CSF470 vaccine is a mixture of four lethally irradiated melanoma cell lines, administered with BCG and GM-CSF, which is currently being tested in a Phase II/III Clinical trial in stage II/III melanoma patients. To prepare vaccine doses, irradiated melanoma cell lines are frozen using dimethyl sulfoxide (Me(2)SO) and stored in liquid nitrogen (liqN(2)). Prior to inoculation, doses must be thawed, washed to remove Me(2)SO and suspended for clinical administration. Avoiding the use of Me(2)SO and storage in liqN(2) would allow future freeze-drying of CSF470 vaccine to facilitate pharmaceutical production and distribution. We worked on the development of an alternative cryopreservation methodology while keeping the vaccine's biological and immunogenic properties. We tested different freezing media containing trehalose suitable to remain as excipients in a freeze-dried product, to cryopreserve melanoma cells either before or after gamma irradiation. Melanoma cells incorporated trehalose after 5 h incubation at 37°C by fluid-phase endocytosis, reaching an intracellular concentration that varied between 70-140 mM depending on the cell line. Optimal freezing conditions were 0.2 M trehalose and 30 mg/ml human serum albumin, at -84°C. Vaccine doses could be frozen in trehalose at -84°C for at least four months keeping their cellular integrity, antigen expression and apoptosis/necrosis profile after gamma-irradiation as compared to Me(2)SO control. Non-irradiated melanoma cell lines also showed comparable proliferative capacity after both cryopreservation procedures. Trehalose-freezing medium allowed us to cryopreserve melanoma cells, either alive or after gamma irradiation, at -84°C avoiding the use of Me(2)SO and liqN(2) storage. These cryopreservation conditions could be suitable for future freeze-drying of CSF470 vaccine.

Anti-ganglioside anti-idiotypic vaccination: more than molecular mimicry

Surgery, chemotherapy, and radiation therapy are standard modalities for cancer treatment, but the effectiveness of these treatments has reached a plateau. Thus, other strategies are being explored to combine with the current treatment paradigms in order to reach better clinical results. One of these approaches is the active immunotherapy based on the induction of anti-tumor responses by anti-idiotypic vaccination. This approach arose from Jerne’s idiotypic network theory, which postulates that B lymphocytes forms a functional network, with a role in the establishment of the immune repertoires, in the regulation of natural antibody production and even in the establishment of natural tolerance. Due to the large potential diversity of the immunoglobulin variable regions, the idiotypes repertoire can mimic the universe of self and foreign epitopes, even those of non-protein nature, like gangliosides. Gangliosides are sialic acid-containing glycolipids that have been considered attractive targets for cancer immunotherapy, based on the qualitative and quantitative changes they suffer during malignant transformation and due to their importance for tumor biology. Although any idiotype could be able to mimic any antigen, only those related to antigens involved in functions relevant for organism homeostasis, and that in consequence has been fixed by evolution, would be able not only to mimic, but also to activate the idiotypic cascades related with the nominal antigen. The present review updates the results, failures and hopes, obtained with ganglioside mimicking anti-idiotypic antibodies and presents evidences of the existence of a natural response against gangliosides, suggesting that these glycolipids could be idiotypically relevant antigens.

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.

Application of carbohydrate array technology to antigen discovery and vaccine development

Carbohydrate arrays are a new technology developed for high-throughput evaluation of interactions between carbohydrates and proteins, cells or viruses. Carbohydrate arrays contain many different carbohydrate structures on a solid support. The format allows one to probe hundreds or thousands of potential receptor-ligand interactions while using only tiny amounts of material. Recently, carbohydrate arrays have been applied to vaccine development in several ways. First, carbohydrate arrays have been utilized for the discovery and characterization of carbohydrate antigens. Second, they have been used to evaluate immune responses to vaccine candidates. Third, carbohydrate arrays have been used to identify and characterize reagents necessary for vaccine development. Although still at an early stage, carbohydrate array technology has tremendous potential for accelerating vaccine development.

Recombinant human hexamer-dominant IgM monoclonal antibody to ganglioside GM3 for treatment of melanoma

PURPOSE

L612, a human IgM monoclonal antibody produced by an EBV-transformed human B-cell line, binds to ganglioside GM3 and kills GM3-positive human melanoma cells in the presence of complement. It has been shown to be effective in some patients with late-stage melanoma. L612 consists of hexameric IgM (about 20%), pentameric IgM (about 74%), and other minor IgM molecules. Because hexameric IgM activates complement more effectively than pentameric IgM, we developed and evaluated a hexamer-dominant recombinant IgM for clinical applications.

EXPERIMENTAL DESIGN

Chinese hamster ovary (CHO) cells were transfected with heavy- and light-chain genes of L612, with or without the joining-chain gene. Antitumor effects of the recombinant IgM secreted from CHO cells were evaluated in vitro and in vivo.

RESULTS

Recombinant IgM secreted from CHO cells without the joining chain (designated CA19) was approximately 80% hexameric, whereas recombinant IgM from CHO cells transfected with heavy-, light-, and joining-chain genes (designated CJ45) was about 90% pentameric. Both CA19 and CJ45 recombinant IgMs caused complement-dependent cytotoxicity against human and mouse melanoma cell lines, but the amount of CA19 required for 50% specific cytotoxicity was 5 to 10 times smaller. I.v. injection of CA19 compared with CJ45 or native L612 elicited more profound antitumor activity in nude rats bearing a GM3-positive mouse melanoma xenograft.

CONCLUSIONS

A hexamer-dominant human IgM against GM3 may provide a more potent treatment option for patients with GM3-positive melanoma.

The immune response to disialoganglioside GD3 vaccination in normal dogs: a melanoma surface antigen vaccine

As a result of its metastatic potential, canine malignant melanoma like its human counterpart like its human counter part, has a poor response to conventional treatment protocols. This prompted us to investigate the possibility of enhancing the immune response against the melanoma cell surface antigen, disialoganglioside GD3. Initially a flow cytometric study was designed in which the incidence of GD3 on the cell surface, recognized by the monoclonal antibody Mel-1 (R24), was established in canine melanoma cell lines. Results from the flow cytometry found GD3 to be highly expressed (94.2%) in six out of seven canine melanoma cell lines. Since it was thus potentially a good target, a study in which normal dogs were vaccinated intradermally with a vaccine containing GD3 plus adjuvants was designed. The adjuvant included CpG oligodeoxynucleotide (CpG-ODN) sequences and RIBI-adjuvant, which are known to target toll-like receptors (TLR) of the innate immune system. From a cohort of 10 dogs, 4 were vaccinated 3 times, at 4 weekly intervals with GD3 plus adjuvant, and 4 received only RIBI-adjuvant, and 2 phosphate buffered saline. Caliper measurements were collected to assess skin reaction at the vaccination site and sera assayed for IgM and IgG antibodies against GD3 and cell-mediated cytotoxicity against a melanoma cell line. Results from the study found significant differences (P<0.05) in the vaccine site reactions, IgM/IgG levels and cell-mediated cytotoxicity in the vaccinated versus unvaccinated dogs. The addition of CpG-ODN sequences and increasing GD3 concentration in the vaccine increased the inflammation response at the injection site. GD3 IgG and IgM antibodies in vaccinated dogs showed increasing titers over time and achieved significance at weeks 9 and 12, respectively. Cell-mediated cytotoxicity was only detected in peripheral blood mononuclear cells from vaccinated dogs. In conclusion, by combining the tumor antigen GD3 (a known weak self-antigen) and an adjuvant, tolerance was overcome by an innate and adaptive immune response in this population of normal dogs.

Cellular and humoral immune response to N-Glycolyl-GM3 elicited by prolonged immunotherapy with an anti-idiotypic vaccine in high-risk and metastatic breast cancer patients

In this study, the immunogenicity and toxicity profile of 1E10, an anti-idiotypic vaccine mimicking the N-glycolyl-GM3 ganglioside, was investigated with an extended vaccination protocol. The year-long vaccination scheme consisted of 6 biweekly intradermal injections (induction phase), followed by 10 monthly boosters (maintenance). Nineteen patients with high-risk (stage III) or metastatic breast cancer were vaccinated with different dose levels of 1E10 (0.5, 1, and 2 mg). The humoral and cellular responses to 1E10 and the targeted ganglioside were assessed at baseline and throughout the treatment. Local skin reactions represented the most common adverse event (National Cancer Institute Toxicity Criteria (NCIC) grades I and II), followed by mild flu-like symptoms lasting for 1 to 2 days. Two patients were removed from the study because of vaccine-related hypersensitivity reactions. A third patient was removed from the study after a transient loss of consciousness with uncertain relation to the vaccine. All patients showed a strong antibody response to the targeted ganglioside. In addition, ganglioside-specific T-cell responses were recorded in 5 of 13 evaluable patients. Vaccination with 1E10 was immunogenic and relatively well tolerated. Because similar results were observed with the 3 tested dose levels, the 0.5-mg dose level was selected for future trials.

Endogenous immune response to gangliosides in patients with confined prostate cancer

Our study investigated whether endogenous IgM antibodies to gangliosides occur in patients with early stages of prostate cancer (CaP) patients, after defining ganglioside profiles of CaP cell lines. Immune and resorcinol staining detected the presence of gangliosides GM3, GM2, GD3, GD2 and GD1a but not GM1a, GD1b or GT1b in the extracts of normal prostatic epithelial cells (PrEC) and neoplastic androgen-insensitive (PC-3, DU145) and -sensitive (LNCaP-FGC and LNCaP-FGC-10) CaP cells. Using a sensitive ELISA, developed and validated in our laboratory, the titers of IgM against 8 gangliosides from sera of patients with benign prostatic hyperplasia (BPH) (n = 11), organ-confined (T1/T2, n = 36) and unconfined (T3/T4, n = 27) CaP and age-matched healthy men (n = 11) were determined double-blinded. Using ANOVA and Fisher's least significant difference (LSD) methods, the log-titers among different groups were compared. CaP patients differed from healthy and BPH patients in increased titers against GD1a and decreased titers against GD3. Titers of antibodies to other gangliosides exhibited no difference between CaP patients and others. The specific augmentation of anti-GD1a IgM in patients with organ-confined CaP (stage T1/T2) but not in patients with unconfined CaP (stage T3/T4) or BPH or in healthy controls is striking. This finding together with identification of GD1a as a major ganglioside in CaP cell lines and with the accruing studies on the immunosuppressive nature of GD1a indicates that augmentation of anti-GD1a IgM in confined CaP may signify an early endogenous immune response to eliminate a "danger signal" from tumor microenvironment and circulation.

Carbohydrate vaccines as immunotherapy for cancer

Carbohydrates have established themselves as the most clinically relevant antigens of those tested and subsequently developed for vaccines against infectious diseases. However, in cancer patients, many of the defined carbohydrate antigens are really altered 'self' antigens and for unclear reasons, the body does not react to them immunologically. Although these self antigens have been found to be potentially suitable targets for immune recognition and killing, the development of vaccines for cancer treatment is actually more challenging compared with those for infectious diseases mainly because of the difficulty associated with breaking the body's immunological tolerance to the antigen. These antigens lack the inherent immunogenicity associated with bacterial antigens and, therefore, methods to enhance immunological recognition and induction of immunity in vivo are under investigation. These include defining the appropriate tumour-associated antigen, successfully synthesizing the antigen to mimic the original molecule, inducing an immune response, and subsequently enhancing the immunological reactivity so that all components can work together. This has been successfully accomplished with several glycolipid and glycoprotein antigens using carriers such as keyhole limpet haemocyanin (KLH) together with a saponin adjuvant, QS-21. Not only can high titre IgM and IgG antibodies be induced, which are specific for the antigen used for immunization, but the antibodies can mediate complement lysis. The approaches for synthesis, conjugation, clinical administration and immunological potential are discussed.

AIDP and CIDP having specific antibodies to the carbohydrate epitope (-NeuAcalpha2-8NeuAcalpha2-3Galbeta1-4Glc-) of gangliosides

Anti-ganglioside antibodies were investigated in plasma exchange solutions (PEs) from two patients with acute and chronic inflammatory demyelinating neuropathies (AIDP and CIDP). Both cases show markedly elevated antibody titers against the lacto-series gangliosides, GM3, GD3, and GT3. In the CIDP patient, the IgG antibody titer to GD3 was remarkably elevated (titer, 1:10,000), indicating maximal avidity to the tetrasaccharide epitope (-NeuAcalpha2-8NeuAcalpha2-3Galbeta1-4Glc-). There were also activities toward GM4 and GM2 with the affinity higher to GM4 than to GM2, indicating that the antibody activity was not highly specific. In contrast, the antibody activities in the AIDP patient showed similar avidity to GM3, GD3, and GT3. These two patients are very rare cases that have not previously encountered in GBS. The effects on co-cultured cells of rat spinal cord and muscle differed according to which PE was used. PE from the AIDP patient produced an inhibitory effect (reduction to 26.8%) on the spontaneous muscle action potential of the neuromuscular junction (NMJ), but the PE from the CIDP patient did not. Thus, in AIDP, the common epitope of GM3, GD3, or GT3 may be shared with certain antigens localized in the peripheral nervous system (PNS) and may participate in a component of conduction-related molecules in the NMJ. High titers of anti-GD3 antibody and the distortion of antibody recognition found in CIDP seem to have no immediate effect on electrophysiologic function in the PNS.

Active specific immunotherapy of melanoma with a GM3 ganglioside-based vaccine: a report on safety and immunogenicity

A novel cancer vaccine was obtained by combining GM3 ganglioside with Neisseria meningitidis outer membrane protein complex to obtain very-small-size proteoliposomes (GM3/VSSP). The authors report the results of a phase 1 study of intramuscular administration of GM3/VSSP/Montanide ISA 51 to patients with metastatic melanoma. Twenty-six patients were included in three dose-level cohorts of 120, 240, and 360 mug. The first five doses (induction phase) were given at 2-week intervals, and the remaining four doses were given monthly. Patients were evaluated for dose-related toxicities and antitumor effects. In addition, serum and peripheral blood mononuclear cells were obtained at baseline and throughout treatment to evaluate humoral and cellular immune responses. One episode of severe hypotension and fever was observed in a patient included at the highest dose level. Other toxicities consisted of local reactions at the site of injection and mild fever and chills. Five doses of GM3/VSSP induced an anti-GM3 IgM response in 44% of patients. Serum reactivity was also observed against melanoma cell lines and tumor biopsies. GM3/VSSP was shown to induce very strong in vitro IFNgamma secretion in all evaluated melanoma patients. Furthermore, in one patient IFNgamma secretion was shown to be GM3-specific. A 62% reduction of a mediastinal mass was documented in one patient (partial response), while a second patient benefited from initial disease stabilization followed by tumor reduction in nonmeasurable soft tissue lesions accompanied by vitiligo.

Sequential immunization of melanoma patients with GD3 ganglioside vaccine and anti-idiotypic monoclonal antibody that mimics GD3 ganglioside

GD3 ganglioside is an attractive target for immunotherapy of melanoma because it is abundantly expressed on all melanomas but not expressed on most normal tissues. Although GD3 has proven to be one of the least immunogenic gangliosides, our recent studies showed that anti-GD3 antibodies can be induced in patients immunized either with GD3-lactone-KLH (GD3-L-KLH) plus QS-21 adjuvant or with BEC2 anti-idiotypic monoclonal antibody vaccine, which mimics GD3, plus Bacillus Calmette-Guérin. We compared the immunogenicity of these two vaccines and tested whether one vaccine could prime an antibody response to the other. This is the first clinical trial immunizing patients with both antigen and anti-idiotypic monoclonal antibody vaccine. Twenty-four melanoma patients were randomized to be immunized with either BEC2 followed by GD3-L-KLH or in the opposite order. Our prior study suggested that a 25-microg dose of BEC2 was more immunogenic than our standard dose of 2.5 mg and therefore was used in this trial. Overall, 10 of 24 patients (42%) developed anti-GD3 antibodies detectable by ELISA, five in each cohort. All antibody responses were in response to the GD3-L-KLH vaccine. We found no evidence of priming by either vaccine. Antibody responses did not correlate with survival outcomes. Cellular responses were detected by enzyme-linked immunospot against BEC2, Bacillus Calmette-Guérin, and KLH, but not against GD3. We confirmed that GD3-L-KLH vaccine induces anti-GD3 antibodies, but we were unable to confirm our previous finding that a 25-microg dose of BEC2 is immunogenic. Future multivalent ganglioside vaccines should include the GD3-L-KLH vaccine.

Metastatic melanoma secreted IL-10 down-regulates CD1 molecules on dendritic cells in metastatic tumor lesions

CD1 molecules are expressed by antigen-presenting cells such as dendritic cells and mediate primary immune responses to lipids and glycolipids which have been shown to be expressed by various tumors. Glycolipids are expressed by melanoma cells but, despite their immunogenicity, no efficient spontaneous immune responses are elicited. As IL-10 has previously been shown to down-regulate CD1a on dendritic cells and is known to be expressed by various melanoma cell lines, we investigated if melanoma-derived IL-10 could down-regulate CD1 molecule expression on dendritic cells as a possible way to circumvent immune recognition. We found that CD1a, CD1b, CD1c, and CD1d were significantly down-regulated on dendritic cells in metastatic (n = 10) but not in primary melanoma lesions (n = 10). We further detected significantly higher IL-10 protein levels in metastatic than in primary melanomas. Moreover, supernatants from metastatic melanomas were significantly more effective in down-regulating CD1 molecules on dendritic cells than supernatants from primary melanoma cultures. This effect was blocked using a neutralizing IL-10 antibody in a dose dependent manner. Our findings suggest that metastatic but not primary melanomas can down-regulate CD1 molecules on infiltrating dendritic cells by secreting IL-10 which may represent a novel way to escape the immune response directed against the tumor.

A phase II trial comparing five dose levels of BEC2 anti-idiotypic monoclonal antibody vaccine that mimics GD3 ganglioside

In previous studies, we showed that immunization with 2.5 mg of BEC2, an anti-idiotypic MAb that mimics GD3 ganglioside, can induce antibodies against GD3 in approximately 25% of patients. In this trial, 50 melanoma patients at high risk for recurrence were randomly assigned to one of the five BEC2 dose levels (2.5 microg-10mg) to determine if lower or higher BEC2 doses are more immunogenic. We also tested whether prolonged booster immunizations can enhance the anti-GD3 antibody response. All patients developed detectable IgG against BEC2 except for one patient at the lowest BEC2 dose level. Six patients developed detectable antibody responses to GD3, all of them at the lower three dose levels of BEC2. We conclude that high doses of BEC2 are not necessary to induce anti-GD3 antibody responses and that lower doses may be more immunogenic than the 2.5 mg dose used in previous BEC2 trials. Prolonged booster immunizations did not induce or maintain antibody responses.

Bioengineering of Surface GD3 Ganglioside for Immunotargeting Human Melanoma Cells

N-Propionyl, N-butyryl (N-Bu), and N-benzoyl mannosamine, as precursors of sialic acid biosynthesis, were incubated with human melanoma SK-MEL-28 cells and resulted in the replacement of N-acetyl groups on the cell surface sialic acid residues, including those associated with GD3. Meanwhile, vaccines containing GD3 and modified GD3 tetrasaccharide-keyhole limpet hemocyanin conjugates were synthesized, and BALB/c mice were immunized with them together with monophosphoryl lipid A adjuvant. The GD3Bu-keyhole limpet hemocyanin conjugate raised the highest IgG titers without any cross-reactivity to unmodified GD3. Expression of GD3Bu epitopes on the surface of SK-MEL-28 cells was confirmed in vitro and in vivo by the binding of a polyclonal antiserum and monoclonal antibody (mAb) 2A, both of which specifically recognize GD3Bu, and by mass spectroscopic analysis of glycolipids extracted from cells. Following expression of GD3Bu on the surface of SK-MEL-28 cells, the cells could be lysed by mAb 2A and GD3Bu antiserum in the presence of complement. Although less effective in the control of existing large size tumors ( approximately 10 mm inner diameter) on BALB/c nu/nu mice, mAb 2A in combination with ManNBu effectively protected mice from SK-MEL-28 tumor grafting. This approach may provide a method to augment the immunogenicity of sialylated human antigens and to avoid generating an autoimmune response to them at same time.

Melanoma: adjuvant therapy and other treatment options

Melanoma, diagnosed and treated at its earliest stages, can be successfully cured by surgery alone. However, when metastatic beyond the regional nodes, it is almost uniformly deadly. Adjuvant therapy targeted toward the treatment of microscopic residual disease after surgical resection is the subject of intense scientific investigation because this is the stage at which it is possible to have the greatest impact on disease-free and overall survival. However, standard therapies commonly used for other solid tumors have had disappointing results in the treatment of melanoma in the adjuvant setting. These disappointing results have led researchers and clinicians to work to develop innovative treatment strategies for this disease, most of which center on the use of immunotherapy. The realm of cancer immunotherapy is broad and rapidly expanding; it encompasses strategies using immunomodulating agents, such as interferon and interleukin-2, in addition to a wide range of novel vaccination strategies for the induction of active antitumor immune responses. Although clinical trials continue to be conducted to sort out the safety and efficacy of a myriad of new treatment modalities and novel combinations of the old and the new, data indicate that high-dose interferon-alfa-2b should be offered to appropriately selected intermediate- and high-risk patients with melanoma not involved in an experimental protocol.

Vaccination of patients with solid tumours

The molecular characterisation of human tumour antigens recognised by T cells has provided new impetus for immunisation of patients bearing tumours expressing well-defined antigens. After evaluating the immunogenicity of the new, molecularly characterised antigens in vitro, several clinical studies were conducted to assess the in vivo immunogenicity and the clinical efficacy of vaccines including these antigens. The findings generated by trials based on the administration of peptides or DNA-encoding antigens are discussed to highlight the limits of this therapeutic approach; however, this approach has resulted in some complete and durable regressions, although still in a unsatisfactory small number of cases (5-25%). The recent use of dendritic cells loaded ex vivo with tumour antigens suggests that a high frequency of tumour-specific immune responses can be achieved. Possible means of overcoming the clinical limits and improving the outcome of previous studies are also discussed.

Tumor vaccines: a role in preventing recurrence in melanoma?

Patients presenting with thick primary melanomas or those with regional nodal metastases have a high risk of recurrence after surgery alone. Chemotherapy has limited efficacy in the adjuvant setting, and while the use of high-dose interferon in the adjuvant setting has been reported to improve survival, treatment with interferon is not without significant cost and toxicity. Mounting evidence suggests a prominent role for the immune system in the natural history of melanoma, and the clinical success of interferon highlights the potential for immunotherapy to prevent recurrence. Many researchers hope to use melanoma vaccines to reduce recurrence without significant toxicity, and many different vaccine strategies are under investigation. Peptide vaccines attempt to induce immunity to melanoma MHC-restricted peptide antigens by delivering the peptide to the patient along with an immune adjuvant meant to induce inflammation and stimulate immunity. While peptide vaccines have advantages with regard to cost and feasibility, it is still unclear whether highly purified peptides will stimulate an adequate immune response. An alternative approach is the use of cellular vaccines. Autologous cellular vaccines present all biologically relevant antigens to the immune system, but this is limited to individuals with sufficient tumor to prepare a vaccine. Allogeneic cellular vaccines are based on the fact that melanoma-associated antigens are shared among a large number of patients, so a vaccine prepared from a cultured cell line could stimulate an anti-tumor immune response in many patients. Allogeneic vaccines are available for all patients, and can be standardized, preserved and distributed in a manner akin to any other therapeutic agent. Because of this, they are more readily available for evaluation in large trials, and there are two major allogeneic vaccines presently being evaluated as an adjuvant therapy for melanoma. Several additional approaches to vaccine therapies are being investigated including among others ganglioside vaccines, viral oncolysates, cytokine gene-modified tumor cell vaccines, dendritic cell vaccines, anti-idiotype antibodies and DNA vaccines. While there appears to be tremendous potential for vaccines, it must be remembered that there has been significant interest in immunotherapy for melanoma for over 50 years and, to date, no large prospective, randomized trial has shown a survival benefit.

Immunotherapy of malignant melanoma

Several areas of immunotherapeutic research may ultimately improve the effectiveness of active specific immunotherapy for melanoma and other malignancies. Identification of the most relevant tumor antigens will continue to be a vital component of vaccine design. Optimizing delivery of these antigens by use of adjuvants, dendritic cells, or heat shock proteins will enhance the immunogenicity of vaccines. The use of DNA vaccines to deliver nucleotides that encode relevant antigens and immunologic molecules, such as costimulatory molecules, and the use of targeted therapy with immunocytokines have yielded promising results in animal studies. Finally, cutting-edge techniques such as quantitative polymerase chain reaction and gene/protein microarrays will be used to monitor the response to a vaccine and thereby guide management decisions. Although IFN-alpha 2b is the only FDA-approved adjuvant treatment for AJCC stage IIB/III melanoma, recent data failed to show a benefit in overall survival. For patients with AJCC stage IV melanoma, chemotherapy with dacarbazine is currently the standard of care, with modest response rates of 15% to 20%. The encouraging response rates and low toxicities that were reported in phase I/III trials suggest that active immunotherapy may prove to be the most effective adjuvant therapy. At present, there are no FDA-approved cancer vaccines for malignant melanoma, and the results of ongoing randomized phase III clinical trials are greatly anticipated.

Humoral immune response to a therapeutic polyvalent cancer vaccine after complete resection of thick primary melanoma and sentinel lymphadenectomy

PURPOSE

A therapeutic polyvalent cancer vaccine (Canvaxin vaccine; CancerVax Corp, Carlsbad, CA) induces antibodies to a glycoprotein tumor-associated antigen (TA90). However, endogenous immune responses to TA90 have also been reported. This study examined anti-TA90 antibody responses with respect to the survival of patients who received adjuvant vaccine immunotherapy after resection of thick (> or = 4 mm) primary cutaneous melanoma.

PATIENTS AND METHODS

Serum specimens were obtained from 54 patients immediately before and then 1, 2, 4, and 6 months after wide local excision of thick primary cutaneous melanoma and sentinel lymphadenectomy. All patients were offered adjuvant therapies with the vaccine, high-dose interferon, or other agents. An enzyme-linked immunosorbent assay was used to determine serial serum titers of immunoglobulin G (IgG) and IgM antibodies against TA90. These titers were correlated with clinical course.

RESULTS

Forty-three patients chose vaccine therapy, and 11 patients chose postoperative observation. Preoperative anti-TA90 IgG and IgM titers were similar for vaccine and observation groups (P =.184). At a median follow-up of 26 months, univariate analysis of Cox regression showed that disease-free survival and overall survival of vaccine patients were significantly correlated with maximal IgM response (P =.0006 and.006, respectively) but not with maximal IgG response (P =.73 and.95, respectively). Neither response predicted survival in the observation group.

CONCLUSION

Postoperative vaccine therapy may enhance IgG and IgM immune responses to TA90 after surgical resection, but only the IgM response is correlated with improved survival. These findings may become useful to guide selection of patients for postoperative adjuvant therapy of high-risk melanoma.

Prolonged survival of patients receiving active immunotherapy with Canvaxin therapeutic polyvalent vaccine after complete resection of melanoma metastatic to regional lymph nodes

OBJECTIVE

To determine whether adjuvant postoperative active specific immunotherapy with a therapeutic polyvalent vaccine (PV) called Canvaxin can prolong survival following complete resection of melanoma metastatic to regional nodes (American Joint Committee on Cancer [AJCC] stage III melanoma).

SUMMARY BACKGROUND DATA

Despite complete lymphadenectomy, 5-year overall survival (OS) for patients with melanoma metastatic to regional lymph nodes is only 20% to 50%, depending on the number of tumor-involved nodes. In 1984, the authors began phase II trials of Canvaxin PV as postsurgical adjuvant therapy for AJCC stage III melanoma.

METHODS

Patients who received PV between 1984 and 1998 were compared with patients who did not receive PV postsurgical therapy between 1971 and 1998. The seven covariates recently defined by the AJCC Melanoma Staging Committee (number of metastatic nodes, palpable status, ulceration, age, primary site, pT stage, and gender) were included by Cox regression in a multivariate model of OS. A computerized program matched PV and non-PV patients by these covariates.

RESULTS

Of 2,602 patients who underwent complete lymphadenectomy for AJCC stage III melanoma with regional nodal metastases and were followed up by the same team of oncologists between 1971 and 1998, 935 received PV and 1,667 did not. Median OS and 5-year OS were significantly higher in PV than non-PV patients (56.4 vs. 31.9 months and 49% vs. 37%, respectively; P =.0001). When the non-PV patients were matched by the four most significant covariates, 447 matched pairs were formed between patients seen before or after January 1, 1985, and the OS was not different between the two time periods ( P=.789). However, when the PV patients were matched with non-PV patients by six covariates forming 739 pairs, the PV patients survived longer ( P=.0001). Detailed analysis of the 1,505 patients who were seen or who began vaccine therapy within 4 months after lymphadenectomy, and who had more complete data on the seven prognostic covariates showed that median OS and 5-year OS were higher in 445 PV patients than in 1,060 non-PV patients: 70.4 versus 31 months and 52% versus 37%, respectively (P =.0001). Multivariate Cox regression analysis identified six significant prognostic factors: number of metastatic nodes, size of metastatic nodes, pT stage, ulceration, age, and PV therapy. PV therapy reduced the relative risk of death to 0.64 (95% confidence interval, 0.55-0.76) ( P=.0001); sex and site of primary were of borderline significance.

CONCLUSIONS

This large single-institution study independently confirmed the significance of prognostic covariates in the new AJCC staging system. By using modern statistical methods that controlled for all known prognostic factors, it also demonstrated PV's ability to significantly enhance OS. A multicenter phase III randomized trial is underway to validate the efficacy of PV as a postsurgical adjuvant.

Ganglioside reactive antibodies of IgG and IgM class in sera of patients with differentiated thyroid cancer

We searched for the presence of ganglioside reactive antibodies in sera of patients with differentiated thyroid cancer (DTC). Sera were screened by ELISA with plates coated with GM3(NeuAc), GM3(NeuGc), GM2, GM1, FucGM1, GD3, GD1a or GD1b gangliosides. Ganglioside reactive antibodies were detected more frequently in sera of patients with DTC than in sera of healthy persons, in keeping with the possibility of autoimmunization during carcinogenesis. Antibodies of IgM and IgG classes reactive with FucGM1 occurred most often. However, the infrequent occurrence of ganglioside reactive antibodies, their low titer and lack of correlation between their presence and clinical condition of the patients indicate that determination of these antibodies has no diagnostic value in DTC.

Advances in specific immunotherapy of malignant melanoma

Management of malignant melanoma continues to present a challenge to dermatologists, particularly in advanced cases. In light of the steady increase in the worldwide incidence and mortality rates for melanoma, better understanding of the immune mechanisms regulating melanoma progression and interaction with the host's immune system seems eminently important. New studies on the role of immune mechanisms in the pathogenesis and clinical course of melanoma have recently been published. We review the immune mechanisms involved in tumor progression and ways in which these mechanisms may be applied toward immunotherapeutic management of malignant melanoma.

LEARNING OBJECTIVE

After the completion of this learning activity, participants should be familiar with (1) the immune mechanisms involved in host-tumor interaction and tumor rejection, (2) factors allowing the escape of melanoma cells from immune recognition, and (3) the current rationale for the different types of specific immunotherapy in melanoma. Better understanding of basic mechanisms in tumor immunology should raise awareness of future immunotherapeutic approaches in patients with melanoma, particularly in those who are at high risk of recurrence or who present with advanced disease.

The chemistry and immunochemistry of blood group A, B, H, and Lewis antigens: past, present and future

This article traces reseach on the chemistry and immunochemistry of blood group A, B, H, and Lewis antigens from early work on the identification of soluble sources of these antigens, through the elucidation of the structures of the carbohydrate epitopes responsible for these specificities, to recent work on exploring their possible use as cancer vaccines. The various approaches used in the isolation of oligosaccharides from mucins for use in structural studies are discussed, as are recent efforts in the chemical systhesis of blood group-active oligosaccharides.

Autoimmune and antitumor consequences of antibodies against antigens shared by normal and malignant tissues

There is now a considerable body of information documenting the autoimmune consequences of antibodies induced by growing malignancies, or by passively administered and actively induced antibodies, in cancer patients against antigens shared by normal and malignant tissues. This provides a rich source of information addressing the consequences of autoantibodies against a range of antigens. Antibodies against cell-surface or intracellular antigens in the central nervous system (CNS) or on epithelial surfaces of normal tissues do not generally result in autoimmunity, but the same types and titers of antibodies against cell surface antigens in the subepidermal skin, peripheral nerves, blood, or vascular sites such as the spleen and bone marrow readily induce autoimmunity. The blood brain barrier of the CNS and apical antigen expression and the basement membrane in epithelial tissues, may protect these sites from antibody induced damage. Cancer cells, however, are protected by neither unidirectional antigen expression nor basement membranes. Vaccine induced antibodies against a variety of cancer cell surface antigens have been associated with prevention of tumor recurrence in preclinical models and in vaccinated cancer patients, in the absence of demonstrable autoimmunity. This forms the basis for a series of ongoing Phase III trials with single or polyvalent antigen cancer vaccines designed for optimal antibody induction.

Human IgM monoclonal antibody to ganglioside GM2 and complement suppress virus propagation in ex vivo cultures of lymphocytes from HIV-1 infected patients

HIV-1 infection induces aberrant ganglioside GM2 expression on infected cell lines, and human IgM anti-GM2 monoclonal antibody (L55 Ab) together with normal fresh human serum (FHS) as a source of complement causes complement mediated cytolysis of HIV-1 infected cells as well as HIV-1 particles. We report here that high expression of GM2 was also detected on HIV-1 infected lymphocytes from HIV-1 seropositive patients. L55 Ab effectively suppressed the generation of HIV in the presence of FHS in primarily cultured lymphocytes from HIV-1 infected patients in ex vivo experiments, and the suppression was enhanced additively by AZT. These data suggest that L55 Ab may increase the therapeutic effect of chemotherapy.

Immunochemical quantification of glycoconjugates in serum and cerebrospinal fluid of amyotrophic lateral sclerosis patients

Glycoconjugates in the serum of 73 patients with amyotrophic lateral sclerosis (ALS), 21 cases of other motor neuron diseases and 20 healthy controls were determined. Cerebrospinal fluid (CSF) was studied in 64, 7 and 10 of these subjects, respectively. The level of sialic acid containing glycoconjugates, detected by Maakia amurensis agglutinin (MAA), was decreased in the serum of 61.6% of the ALS patients, while in the CSF it was decreased, on average, in 75% of these cases. Only in single ALS cases was the concentration of these glycoconjugates increased. There was no correlation between the content of MAA-labelled glycoconjugates both in serum and CSF and the titre of sialic acid containing anti-GM1 gangliosides. The glycoconjugates, detected by peanut agglutinin (PNA) which recognizes the disaccharide galactose beta(1-3)N- acetylgalactosamine (GGN), were decreased in the serum of 78.1% of ALS patients, while in CSF they were increased in 54.7% of these cases. There was no correlation between the concentration of PNA-labelled glycoconjugates both in serum and CSF as well as the titre of antibodies against GGN-containing anti-GM1 and anti- AGM1 gangliosides. Changes in the level of the MAA- and PNA- labelled glycoconjugates, as well as the titre of anti-GM1 and anti-AGM1 gangliosides antibodies were not specific for ALS. They were also observed in some cases of other motor neuron diseases. The low level of the lectin-labelled glycoconjugates in serum and partly in CSF of the majority of ALS patients is possibly the consequence of their accelerated clearance and/or specific inactivation by the formation of immune complexes or epitope binding. Degeneration of neurons and muscle cells could also be responsible. The relatively low incidence of high anti- glycolipids antibodies titre may be, at least partly, connected with the low concentration of the appropriate antigens. The increased content of PNA-labelled glycoconjugates in the CSF of the majority of ALS patients, together with the low incidence of high titre of antibodies against the appropriate glycolipids, could indicate that in CSF this lectin binds to the GGN epitope of glycoproteins rather than to the GGN epitope of glycolipids.

IgM anti-ganglioside antibodies induced by melanoma cell vaccine correlate with survival of melanoma patients

Melanoma cells express ganglioside antigens GM3, GD3, GM2, and GD2 on their surface. This study examined whether immunization with a melanoma cell vaccine induced anti-ganglioside antibody responses in melanoma patients and whether these responses were correlated with survival. Sixty-six patients who had received melanoma cell vaccine immunotherapy after surgical removal of regional metastatic melanoma were identified. Cryopreserved serum samples from these patients were used in an enzyme-linked immunsorbent assay to determine the IgM antibody levels to GM2, GD2, GM3, and GD3 prior to melanoma cell vaccine treatment and 4 wk after the first melanoma cell vaccine immunization. All antibody levels significantly increased by week 4 (p < 0.001 for all four antibodies) and all increases were significantly associated with survival (anti-GD2, p < 0.001; anti-GM2, p = 0.001; anti-GD3, p < 0.001; anti-GM3, p < 0.001). Anti-tumor activity of these antibodies was proved using five representative antibody-positive sera in a complement-dependent cytotoxicity assay with cultured melanoma cell lines. These studies suggest that GM2, GD2, GM2, and GD3 expressed by melanoma cells can induce specific IgM antibodies and that high levels of these antibodies might have a beneficial impact on survival.

Complement-Mediated Anti-HIV-1 Effect Induced by Human IgM Monoclonal Antibody Against Ganglioside GM2

HIV-infected cells aberrantly express a high level of antigenic glycosidic structures such as GM2 and Gg4. Some normal sera containing natural IgM Abs to GM2 and/or Gg4 cause C-mediated cytolysis of HIV-infected cells. In the present study we demonstrated that a human IgM anti-GM2 mAb (L55 Ab) can induce cytolysis of HIV-infected cells. Increased GM2 expression by HIV-1 infection of a human T cell line (MOLT4), a human monocyte cell line (U937), and human lymphoblastoid cells was confirmed by immunofluorescence staining with L55 Ab. These infected cells were readily lysed by L55 Ab in the presence of fresh human serum as a C source that alone did not cause cytolysis. L55 Ab also had the ability to destroy HIV-1 particles via C-mediated lysis. By adding L55 Ab together with human C to mixed culture of HIV-infected cells and naive cells, HIV-1 replication was significantly suppressed, and this effect was synergistic when L55 Ab was combined with a reverse transcriptase inhibitor and a proteinase inhibitor. Therefore, a human IgM anti-GM2 mAb may be effective in treating HIV-infected patients, especially when used together with chemotherapeutic agents.

Vaccines and other adjuvant therapies for melanoma

Patients with thick primary melanomas or regional lymph node involvement are at high risk of relapse. Investigations of adjuvant therapy over the past 30 years show only one significantly positive trial employing high dose interferon-alpha-2b. This is a potentially toxic regimen, therefore, other better-tolerated forms of adjuvant immunotherapy are being studied. Recent advances in basic science have led to a better understanding of the T-cell response to human cancer. This article discusses the background and current clinical trials of active specific immunotherapies for melanoma, including peptide and ganglioside vaccines.

Identification of melanoma antigens that are immunogenic in humans and expressed in vivo

BACKGROUND

In the development of an antimelanoma vaccine, a critical factor is the identification of antigens that induce a strong immune response in humans and that are expressed by melanoma cells in vivo. The aim of this study was to identify candidate antigens for such vaccine.

METHODS

Sixty-nine patients with surgically resected melanomas (American Joint Commission on Cancer [AJCC] stage III) were immunized with a polyvalent vaccine containing multiple melanoma antigens. Antimelanoma antibodies generated in the patients' sera were used as probes to identify the melanoma antigens that are immunogenic in humans and that are expressed on the tumor tissue in vivo. Such responses were determined by an immunoblotting assay that employed an antigen source prepared from membrane fractions of freshly excised melanoma tissue.

RESULTS AND CONCLUSIONS

Vaccine treatment stimulated antibody responses in 35 (51%; 95% confidence interval [CI] = 39%-63%) of 69 sequentially enrolled patients. The antibodies were directed to one or more antigens with molecular masses of 45, 59, 68, 79, 89, 95, and/or 110 kd. The most immunogenic antigens were p110 and p68, which induced responses in 33% (95% CI = 22%-44%) and 25% (95% CI = 15%-35%) of patients, respectively. Both antigens were commonly expressed on different melanomas, but they were absent on autologous normal tissue and on an unrelated allogeneic tumor. All the above antigens are attractive candidates for vaccine construction.

Carbohydrate vaccines that induce antibodies against cancer. 2. Previous experience and future plans

The primary function of antibodies is the elimination of circulating viral or bacterial pathogens from the blood-stream, lymphatics and interstitial spaces, and so, once induced, antibodies should be ideally suited for eliminating tumor cells and micrometastases from these spaces as well. Natural or tumor-induced and vaccine-induced antibodies against human cancer-associated antigens have been correlated with an improved clinical outcome. In the mouse, passive administration of monoclonal antibodies against cell-surface antigens 1–4 days after tumor challenge, and active induction of antibodies with vaccines, has resulted in prolonged survival or complete protection from tumor growth. This is a setting similar to the adjuvant setting in humans. Carbohydrates are the most abundant antigens at the cell surface of cancer cells, where they play important roles in cell-cell interactions, proliferation and the metastatic process. They have been shown to be excellent targets for immune attack by antibodies against human cancers, especially in the adjuvant setting. Vaccines containing these carbohydrate antigens covalently attached to immunogenic carrier proteins, such as KLH, plus potent immunological adjuvants, such as QS-21, effectively induce antibodies against these antigens in patients, which can result in complement-mediated lysis of antigen-positive tumor cells. Phase III trials with KLH conjugate vaccines have been initiated in the adjuvant setting against two carbohydrate antigens, the ganglioside GM2 and the blood-group-related antigen sTn. As the immunogenicity of additional vaccines is confirmed in small pilot trials, trials with polyvalent vaccines against two to five different antigens tailored for particular cancer types are planned.

Carbohydrate vaccines that induce antibodies against cancer. 1. Rationale

Carbohydrate antigens are the most abundant antigens expressed at the cancer cell surface and have been shown to be uniquely effective targets for immune recognition and attack. The basis for cancer vaccines that primarily induce an antibody response, such as vaccines against these carbohydrate antigens, is now well established in both experimental models and the clinical setting. In both cases, antibody administration or induction has been especially effective in the adjuvant setting when the targets are circulating tumor cells and micrometastases. The patterns of carbohydrate antigens expressed by different tumor types has been established, paving the way for polyvalent-antibody-inducing vaccines. This then forms the rationale for the construction and testing of carbohydrate vaccines against cancer, the focus of the second part of this review.