DetoxPC

Aberrant glycosylation is one of the most constant traits of malignant cells. The CaMBr1 hexasaccharide antigen, originally defined on the human breast carcinoma cell line MCF7, is expressed on some normal tissues but overexpressed in a high percentage of human breast, ovary, prostate and lung carcinomas. CaMBr1 overexpression is associated with poor prognosis. The epitope consists of the tetrasaccharide Fuc(alpha1-2)Ga1(beta1-3)GalNAc(beta1-3)Ga1alpha-O-spacer, which has recently become available as a synthetic oligosaccharide. Here we report the CaMBr1 tetrasaccharide conjugation to two different carrier proteins (CRM197 and KLH) and the evaluation of conjugate immunogenicity in mice following their administration in various vaccine formulations with two adjuvants (MPL-SE and Detox-PC). Radioimmunoassay to determine the level and isotype of anti-tetrasaccharide antibodies in mouse sera, and cytofluorimetric analysis and 51Cr-release assay on human tumor cells, to evaluate specificity of binding and complement-dependent lysis respectively, identified CaMBr1-CRM197, in association with the MPL-SE adjuvant, as the best vaccine formulation. This combination induced (1) production of tetrasaccharide-specific antibodies, with negligible side-effects; (2) antibodies with complement-mediated cytotoxic activity on human CaMBr1-positive cells and (3) a high titer of IgG1 detected in sera obtained 3 months after the first injection, indicating that the anti-tetrasaccharide antibody response was mediated by T cell activation. The availability of CaMBr1-glycoconjugate in the minimal and functional antigenic structure and the identification of an efficacious vaccine formulation opens the way to exploring the activity of this glycoconjugate in a clinical setting.

A therapeutic lyophilized melanoma vaccine consisting of two mech. disrupted allogeneic melanoma cell lines and the immunol. adjuvant Detox-PC (Melacine) has demonstrated encouraging activity in metastatic malignant melanoma, often in regimens containing pretreatment with low-dose cyclophosphamide.In addition, IFN-α2b (INTRON A; Schering-Plough Corporation, Kenilworth, NJ) has shown efficacy in melanoma refractory to Melacine.In this Phase II trial, the combination of cyclophosphamide, Melacine, and IFNα was tested in metastatic malignant melanoma.Eligibility criteria included measurable disease, no prior systemic therapy for a min. of 4 wk, and adequate marrow, renal, and hepatic function.Cyclophosphamide was administered once at a dose of 300 mg/m² i.v. on day -3 before the first dose of Melacine.Melacine was administered at a dose of 2×10⁷ tumor cell equivalent per dose admixed with 0.25 mL of Detox-PC s.c. once a week on weeks 1-4 and week 6.Melacine maintenance was then given monthly from the 8th week, until progression or intolerable toxicity.IFN was started in the evening after the fourth dose of Melacine at a dose of 5,000,000 units/m² 3 times a week, and continued until progression.Forty-seven patients were enrolled, of whom 39 completed the full course and were considered evaluable.The toxicity of the regimen was minimal and consisted mainly of pain at injection sites and granulomas caused by Detox-PC, and constitutional symptoms attributable to IFN.In 39 evaluable patients, the overall objective response rate was 10.2%, but 64% of patients had stabilization of their disease for at least 16 wk.The median time to disease progression in evaluable patients was 8 mo [95% confidence interval (CI), 6-13 mo].Median survival time for all of the 47 patients enrolled was 12.5 mo (95% CI, 8-15 mo) with a median time to disease progression of 4 mo (95% CI, 3-7 mo).Despite a low objective response rate, this combination holds great promise because of its tolerability and the high proportion of prolonged durations of remission or disease stabilization that it elicited.