Phase I trial of cisplatin, WR-2721, and the murine monoclonal antibody R24 in patients with metastatic melanoma: clinical and biologic effects

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.

Glycans as targets for therapeutic antitumor antibodies

Glycans represent a vast class of molecules that modify either proteins or lipids. They exert and regulate important and complex functions in both normal and cancer cell metabolism. As such, the most immunogenic glycans have been targeted in passive and active immunotherapy in human cancer for the past 25 years but it is only recently that techniques have become available to uncover novel glycan targets. The main focus of this review article is to highlight why and how monoclonal antibodies (mAbs) recognizing glycans, and in particular the glycans expressed on glycolipids, are being used in various strategies to target and kill cancer cells. The article reports on the historical use of mAbs and on very recent progress made in antitumor therapy using the anti-GD2 mAb and the antiganglioside mAbs, anti-N-glycolylneuraminic acid mAb and anti-Lewis mAb. Anti-GD2 is showing great promise in Phase III clinical trials in adjuvant treatment of neuroblastoma. Racotumomab, an anti-idiotypic mAb mimicking N-glycolylneuraminic acid-containing gangliosides, is currently being tested in a randomized, controlled Phase II/III clinical trial. This article also presents various strategies used by different groups to develop mAbs against these naturally poorly immunogenic glycans.

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.

Gangliosides as therapeutic targets for cancer

Gangliosides, sialic acid-containing glycosphingolipids, have engendered great interest for more than 20 years in the search for target molecules of relevance for tumour growth and formation of metastases and as potential targets for immunotherapy. These molecules show large quantitative and structural variability, which is related to cell type and developmental stage. Their potential role in the formation of tumour metastases was suggested from data supporting that they are involved in cell growth regulation and in cell-cell and cell-matrix adhesion. Moreover, gangliosides are expressed on the cell surface and thereby are accessible for antibodies or other ganglioside-binding molecules to induce cell death, inhibit cell growth and/or inhibit formation of tumour metastasis. All tumours exhibit aberrant ganglioside expression. This includes overexpression of normal ganglioside constituents, which appears to be common among various tumours, and expression of gangliosides not found in normal adult tissue but often found during fetal development. The ganglioside composition of melanoma cells has been found to correlate with their metastatic potential and also to be selectively expressed in cells of a tumour mass and invading tumour cells. Passive immunotherapy using murine or murine/human chimeric monoclonal antiganglioside antibodies in their native form or combined with various effector molecules has been investigated. However, the vaccination strategy using native or structurally modified tumour-associated gangliosides in combination with adjuvants is currently the dominant method in clinical trials. The outcomes reported so far vary between type of tumour and treatment strategies. However, we believe that targeting gangliosides is as promising as any other immune therapeutic strategy, and basic research as well as clinical trials utilising new aspects is encouraged.

Specific targeting, biodistribution, and lack of immunogenicity of chimeric anti-GD3 monoclonal antibody KM871 in patients with metastatic melanoma: results of a phase I trial

PURPOSE

KM871 is a chimeric monoclonal antibody against the ganglioside antigen GD3, which is highly expressed on melanoma cells. We conducted an open-label, dose escalation phase I trial of KM871 in patients with metastatic melanoma.

PATIENTS AND METHODS

Seventeen patients were entered onto one of five dose levels (1, 5, 10, 20, and 40 mg/m2). Patients received three infusions of KM871 at 2-week intervals, with the first infusion of KM871 trace-labeled with indium-111 (111In) to enable assessment of biodistribution in vivo. Biopsies of metastatic melanoma sites were performed on days 7 to 10.

RESULTS

Fifteen of 17 patients completed a cycle of three infusions of KM871. No dose-limiting toxicity was observed during the trial; the maximum-tolerated dose was therefore not reached. Three patients (at the 1-, 5-, and 40-mg/m2 dose levels) developed pain and/or erythema at tumor sites consistent with an inflammatory response. No normal tissue uptake of 111In-KM871 was observed, and tumor uptake of 111In-KM871 was observed in all lesions greater than 1.5 cm (tumor biopsy 111KM871 uptake results: range, 0.001% to 0.026% injected dose/g). The ratio of maximum tumor to normal tissue was 15:1. Pharmacokinetic analysis revealed a 111In-KM871 terminal half-life of 7.68 +/- 2.94 days. One patient had a clinical partial response that lasted 11 months. There was no serologic evidence of human antichimeric antibody in any patient, including one patient who received 16 infusions over a 12-month period.

CONCLUSION

This study is the first to demonstrate the biodistribution and specific targeting of an anti-GD3 antibody to metastatic melanoma in patients. The long half-life and lack of immunogenicity of KM871 makes this antibody an attractive potential therapy for patients with metastatic melanoma.

Phase IB trial for malignant melanoma using R24 monoclonal antibody, interleukin-2/alpha-interferon

The inflammatory tumor lymphocytic infiltrates and spontaneous tumor regressions seen in patients with metastatic malignant melanomas suggest a cellular immune involvement. Enhancement of such responses has been the goal of R24 (GD3 ganglioside-specific) monoclonal antibody trials, alone and in combination with other agents. This study reports the results of 21 patients treated in a phase IB trial employing R24 (0, 5, 25, 50 mg/m2) administered by continuous i.v. infusion on days 1-5 followed by 3 MU each of interleukin-2 (IL-2) and alpha interferon (alpha-IFN) given subcutaneously on days 8-12, 15-19 and 22-26. R24-related toxicities occurred pre-dominantly at the 25 and 50 mg/m2 doses. One patient (50 mg/m2 R24) exhibited a dose-limiting Grade 4 anaphylaxis. Cytokine-related toxicities required IL-2/alpha-IFN dose reduction in two patients and early termination of treatment in five additional patients. Nine of 20 baseline biopsies showed chronic inflammation; six with lymphocytic tumor infiltration and three where inflammation was confined to the perivascular/peritumoral spaces. No day 8 or 29 biopsies in the R24-treated groups demonstrated treatment-induced tumor lymphocytic infiltrates. However, one patient randomized to no R24 treatment, showed a significant inflammatory tumor lymphocytic infiltration at days 8 and 29. Eighteen of 21 treated patients were evaluable for response. One (5%) patient receiving IL-2/alpha-IFN alone had stable disease lasting 1.5 years. Five (28%) R24, IL-2/alpha-IFN-treated patients had stable disease ranging from 6 to 32 weeks, with one patient remaining alive 2.5 years post-treatment. Although this combined treatment program was generally well tolerated, no objective responses were seen and significant R24-induced tumor lymphocytic infiltrates were not demonstrated.

Amifostine (Ethyol): dosing, administration and patient management guidelines

Cytoprotection utilising amifostine (Ethyol, WR-2721) is an evolving strategy to protect normal cells from the toxicity of chemotherapy. The dosing and administration guidelines are reviewed. The recommended dose of amifostine is 910 mg/m2 as a 15-min infusion prior to chemotherapy. Toxicity of this agent is moderate with hypotension and nausea/vomiting being observed in variable numbers of patients. Administration of amifostine with chemotherapy is simple and is associated with acceptable toxicity.

Amifostine: potential for clinically useful cytoprotection

The ability to target malignant cells for cytotoxicity while sparing normal host tissues has proven to be limited. These limitations have resulted in unacceptable toxicity or insufficiently effective therapy. Continuing investigation of new, potentially useful cytotoxic agents must continue. An alternative approach, also worthy of study, is the selective protection of normal tissues. This approach, used in conjunction with available therapeutic agents, may open the therapeutic window and incrementally enhance the effectiveness of cytotoxic therapy. A variety of methods have been used to protect normal tissues selectively. Regional protection can be used for certain organ systems, such as the oral mucosa. Selective protection on a systemic level is more difficult but agents that seem to protect normal but not malignant tissues selectively are being developed. Among these is amifostine, which was originally selected by the U.S. defense department for study as a radioprotectant. Pre-clinical studies have suggested that amifostine is differentially concentrated in normal tissues but not in malignant tissues. Tissue-specific differences in the activity of alkaline phosphatase, which dephosphorylates amifostine to its active metabolite WR-1065, and in pH are thought to be involved in this relative specificity. Clinical studies indicate that amifostine can reduce the myelosuppression produced by cyclosphosphamide, the combination of cyclophosphamide and cisplatin, and, perhaps, carboplatin. The protective effects of amifostine on nonhematopoietic toxicities are being investigated. Future trials will investigate the integration of amifostine with cytokine-based supportive care in order to define the role of this potentially clinically useful cytoprotectant agent.