Autophagic flux is impaired in the brain tissue of Tay-Sachs disease mouse model.

Tay-Sachs disease is a lethal lysosomal storage disorder caused by mutations in the HexA gene encoding the α subunit of the lysosomal ß-hexosaminidase enzyme (HEXA). Abnormal GM2 ganglioside accumulation causes progressive deterioration in the central nervous system in Tay-Sachs patients. Hexa-/- mouse model failed to display abnormal phenotype. Recently, our group generated Hexa-/-Neu3-/- mouse showed severe neuropathological indications similar to Tay-Sachs patients. Despite excessive GM2 ganglioside accumulation in the brain and visceral organs, the regulation of autophagy has not been clarified yet in the Tay-Sachs disease mouse model. Therefore, we investigated distinct steps of autophagic flux using markers including LC3 and p62 in four different brain regions from the Hexa-/-Neu3-/- mice model of Tay-Sachs disease. Our data revealed accumulated autophagosomes and autophagolysosomes indicating impairment in autophagic flux in the brain. We suggest that autophagy might be a new therapeutic target for the treatment of devastating Tay-Sachs disease.

Chemical Synthesis of GM2 Glycans, Bioconjugation with Bacteriophage Qß, and the Induction of Anticancer Antibodies.

The development of carbohydrate-based antitumor vaccines is an attractive approach towards tumor prevention and treatment. Herein, we focused on the ganglioside GM2 tumor-associated carbohydrate antigen (TACA), which is overexpressed in a wide range of tumor cells. GM2 was synthesized chemically and conjugated with a virus-like particle derived from bacteriophage Qß. Although the copper-catalyzed azide-alkyne cycloaddition reaction efficiently introduced 237 copies of GM2 per Qß, this construct failed to induce significant amounts of anti-GM2 antibodies compared to the Qß control. In contrast, GM2 immobilized on Qß through a thiourea linker elicited high titers of IgG antibodies that recognized GM2-positive tumor cells and effectively induced cell lysis through complement-mediated cytotoxicity. Thus, bacteriophage Qß is a suitable platform to boost antibody responses towards GM2, a representative member of an important class of TACA: the ganglioside.

Serologic evidence of autoimmunity in E2696 and E1694 patients with high-risk melanoma treated with adjuvant interferon alfa.

We evaluated Eastern Cooperative Group phase II and III trials E2696 and E1694 to assess the incidence and prognostic significance of autoimmunity induced by adjuvant high-dose interferon-α2b (HDI). In E2696, patients with resectable high-risk melanoma were randomized to receive vaccination with GM2-KLH/QS-1 (GMK) plus concurrent HDI, GMK plus sequential HDI, or GMK alone. E1694 randomized patients to either HDI or GMK. Sera from 103 patients in E2696 and 691 patients in E1694 banked at baseline and up to three subsequent time points were tested by ELISA for the development of five autoantibodies. In E2696, autoantibodies were induced in 16 patients (23.2%; n=69) receiving HDI and GMK and two patients (5.9%; n=34) receiving GMK alone (P=0.031). Of 691 patients in E1694, 67 (19.1%) who received HDI (n=350) developed autoantibodies, but only 16 patients (4.7%) developed autoantibodies in the vaccine group (n=341; P<0.001). Almost all induced autoantibodies were detected at ≥12 weeks after the initiation of therapy. A 1-year landmark analysis among resected stage III patients treated with HDI in E1694 showed a trend toward a survival advantage associated with HDI-induced autoimmunity (hazard ratio=0.80; 95% confidence interval: 0.50-1.98; P=0.33). Therefore, adjuvant HDI therapy is associated with the induction of autoimmunity that should be further investigated prospectively as a surrogate marker of adjuvant therapeutic benefit. This potential biomarker develops over the course of up to 1 year, and cannot be used to alter the course of therapy. Studies of the genetic determinants of this response may better discriminate patients more likely to benefit from HDI immunomodulatory therapy.

Adjuvant ganglioside GM2-KLH/QS-21 vaccination versus observation after resection of primary tumor > 1.5 mm in patients with stage II melanoma: results of the EORTC 18961 randomized phase III trial.

PURPOSE: The GM2 ganglioside is an antigen expressed in the majority of melanomas. The GM2-KLH/QS-21 vaccine induces high immunoglobulin M (IgM) and IgG antibody responses. The EORTC 18961 trial compared the efficacy of GM2-KLH/QS-21 vaccination versus observation. PATIENTS AND METHODS: A total of 1,314 patients with a primary tumor > 1.50 mm in thickness (T3-4N0M0; American Joint Committee on Cancer stage II) were randomly assigned to GM2-KLH/QS-21 vaccination (n = 657) or observation (n = 657). Treatment consisted of subcutaneous injections once per week from week 1 to 4, then every 3 months for the first 2 years and every 6 months during the third year. Primary end point was relapse-free survival (RFS). Secondary end points were distant metastasis-free survival (DMFS) and overall survival (OS). Analyses were by intent to treat. RESULTS: After a median follow-up of 1.8 years, the trial was stopped at the second interim analysis for futility regarding RFS (hazard ratio [HR], 1.00; P = .99) and detrimental outcome regarding OS (HR, 1.66; P = .02). After a median follow-up of 4.2 years, we had recorded 400 relapses, nine deaths without relapse, a total of 236 deaths. At 4 years, the vaccination arm showed a decreased RFS rate of 1.2% (HR, 1.03; 95% CI, 0.84 to 1.25) and OS rate of 2.1% (HR, 1.16; 95% CI, 0.90 to 1.51). Toxicity was acceptable, with 4.6% of patients ending study participation because of toxicity. CONCLUSION: GM2-KLH/QS-21 vaccination does not improve outcome for patients with stage II melanoma.

Synthesis of ganglioside epitopes for oligosaccharide specific immunoadsorption therapy of Guillian-Barré syndrome.

Guillain-Barré syndrome is a postinfectious, autoimmune neuropathy resulting in neuromuscular paralysis. Auto-antibodies, often induced by bacterial infection, bind to human gangliosides possessing monosialoside and diasialoside epitopes and impair the function of nerve junctions, where these ganglioside structures are highly enriched. Truncated gangliosides representive of GD3, GQ1b and GM2 epitopes have been synthesized as methyl glycosides and as a glycosides of an eleven carbon tether. The synthetic oligosaccharide ligands are structural mimics of these highly complex ganglioside epitopes and via their ability to neutralize or remove auto-antibodies have the potential for therapy, either as soluble blocking ligands administered systemically, or as immuno-affinity ligands for use as extracorporeal immunoadsorbents.

A Bayesian semiparametric joint hierarchical model for longitudinal and survival data.

This article proposes a new semiparametric Bayesian hierarchical model for the joint modeling of longitudinal and survival data. We relax the distributional assumptions for the longitudinal model using Dirichlet process priors on the parameters defining the longitudinal model. The resulting posterior distribution of the longitudinal parameters is free of parametric constraints, resulting in more robust estimates. This type of approach is becoming increasingly essential in many applications, such as HIV and cancer vaccine trials, where patients' responses are highly diverse and may not be easily modeled with known distributions. An example will be presented from a clinical trial of a cancer vaccine where the survival outcome is time to recurrence of a tumor. Immunologic measures believed to be predictive of tumor recurrence were taken repeatedly during follow-up. We will present an analysis of this data using our new semiparametric Bayesian hierarchical joint modeling methodology to determine the association of these longitudinal immunologic measures with time to tumor recurrence.

High-dose interferon alfa-2b does not diminish antibody response to GM2 vaccination in patients with resected melanoma: results of the Multicenter Eastern Cooperative Oncology Group Phase II Trial E2696.

PURPOSE: High-dose interferon alfa-2b (IFNalpha2b) is the only established adjuvant therapy of resectable high-risk melanoma. GM2-KLH/QS-21 (GMK) is a chemically defined vaccine that is one of the best developed of a range of vaccine candidates for melanoma. A single-institution phase III trial conducted at Memorial Hospital served as the impetus for an intergroup adjuvant E1694/S9512/C509801 trial, which recently completed enrollment of 880 patients. To build on the apparent benefit of IFNalpha2b in resectable high-risk American Joint Committee on Cancer (AJCC) stage IIB or III melanoma, this phase II study was designed to evaluate the combination of GMK and IFNalpha2b. The E2696 trial was undertaken to evaluate the toxicity and other effects of the established adjuvant high-dose IFNalpha2b regimen in relation to immune responses to GMK and to evaluate the potential clinical and immunologic effects of the combined therapies. PATIENTS AND METHODS: This trial enrolled 107 patients with resectable high- or very high-risk melanoma (AJCC stages IIB, III, and IV). RESULTS: The results demonstrate that IFNalpha2b does not significantly inhibit immunoglobulin M or G serologic responses to the vaccine and that the combination of high-dose IFNalpha2b and GMK is well tolerated in this patient population. CONCLUSION: Cox analysis of the results of the combination with IFNalpha2b show improvement in the relapse-free survival of patients with very high-risk melanoma (including those with resectable M1 disease).

Cancer immunomodulation by carbohydrate ligands for the lymphocyte receptor NKR-P1.

Natural killer (NK) and T cells express a superfamily of proteins with structural features of C-type lectins. Recombinantly prepared soluble form of rat NKR-P1 (CD161) recognized carbohydrate GalNac and GlcNac moieties. Ganglioside GM2 and heparin related-IS oligosaccharides representing the high affinity ligands for this receptor, increased the sensitivity of targets for killing by the rat effectors isolated from blood and spleen in vitro. Based on these results, we investigated in vivo the possible therapeutic effect of GM2 and IS carried by liposomes during induced rat colorectal carcinogenesis. The reduction of cancer incidence versus the controls (50% vs 88.88%), approached the 5-fluorouracil treatment (41.66%).

Vaccination with a bivalent G(M2) and G(D2) ganglioside conjugate vaccine: a trial comparing doses of G(D2)-keyhole limpet hemocyanin.

Immunization with GMK vaccine (G(M2) ganglioside conjugated to keyhole limpet hemocyanin mixed with QS-21 adjuvant) induces anti-G(M2) antibodies in close to 100% of patients. We found previously that anti-G(D2) antibodies could be induced in some patients using G(D2)-keyhole limpet hemocyanin + QS-21 (GDK). In this trial, we wished: (a) to determine whether immunization with both GMK and GDK vaccines could induce antibodies against both G(M2) and G(D2); and (b) to determine the optimal dose of GDK. Thirty-one patients with melanoma or sarcoma who had no evidence of disease after complete surgical resection were immunized with both GMK (30 microg of G(M2)) and GDK on weeks 1, 2, 3, 4, 12, 24, and 36. Patients were assigned to one of five GDK dose levels (3, 10, 30, 70, or 130 microg of G(D2)). Anti-G(M2) IgM or IgG were induced in 97% of patients. The dose of GDK did not affect the anti-G(M2) response, although at the highest GDK dose level, 3 of 7 patients did not make anti-G(M2) IgG. GDK was less immunogenic; overall 45% of patients developed either IgM or IgG against G(D2). At GDK doses of 30 or 70 microg, 8 of 11 patients (73%) made either IgM or IgG anti-G(D2) antibodies. We conclude that both GMK and GDK vaccines can induce antibodies against G(M2) and G(D2) in a majority of patients and are safe. The optimal dose of GDK appears to be either 30 or 70 microg when administered with GMK vaccine.

Improved survival in stage III melanoma patients with GM2 antibodies: a randomized trial of adjuvant vaccination with GM2 ganglioside.

PURPOSE: To perform a double-blind randomized trial with American Joint Commission on Cancer (AJCC) stage III melanoma patients for the following reasons: (1) to confirm our previous finding that patients with antibodies against the melanoma differentiation antigen GM2 have an improved prognosis, and (2) to demonstrate clinical benefit from GM2 antibody induction. PATIENTS AND METHODS: One hundred twenty-two patients with AJCC stage III melanoma who were free of disease after surgery were randomized: 58 to receive treatment with the GM2/BCG vaccine, and 64 to receive treatment with bacille Calmette-Guèrin (BCG) alone. All patients were pretreated with low-dose cyclophosphamide (Cy). RESULTS: GM2 antibody was detected in 50 of 58 patients treated with GM2/BCG and seven of 64 patients treated with BCG alone. With a minimum follow-up period of 51 months, there was a highly significant increase in the disease-free interval (P = .004) and a 17% increase in overall survival (P = .02) in these 57 antibody-positive patients, confirming our earlier experience. Exclusion of all patients with preexisting GM2 antibodies (one in the GM2/BCG group and five in the BCG group) from statistical analysis resulted in a 23% increase in disease-free interval (P = .02) and a 14% increase in overall survival (P = .15) at 51 months for patients treated with the GM2/BCG vaccine. However, when all patients in the two treatment groups were compared as randomized, these increases were 18% for disease-free interval and 11% for survival in the GM2/BCG treatment group, with neither result showing statistical significance. CONCLUSION: (1) Vaccination with GM2/BCG induced immunoglobulin M (IgM) antibodies in most patients. (2) GM2 antibody production was associated with a prolonged disease-free interval and survival. (3) Comparison of the two arms of this trial as randomized fails to show a statistically significant improvement in disease-free interval or survival for patients treated with GM2/BCG vaccines.