Induction of antibodies against GD3 ganglioside in melanoma patients by vaccination with GD3-lactone-KLH conjugate plus immunological adjuvant QS-21

The gangliosides GD3, GD2 and GM2 are expressed on the cell surface of mali gnant melanomas, GD3 being the most abundant. We have shown that immunizati on of melanoma patients with GM2 adherent to Bacillus Calmette-Guerin (CM2/ BCG) induced an IgM antibody response. Vaccines containing GM2-keyhole limp et hemocyanin (KLH) conjugate and the immunological adjuvant QS-21 induced a higher titer IgM response and consistent IgG antibodies. Patients with an tibodies against GM2 survived longer than patients without antibody. On the other hand, our previous trials with GD3/ BCC, GD3 derivatives including G D3-lactone (CD3-L)/BCG failed to induce antibodies against GD3. In our cont inuing efforts to induce antibody against GD3, we have immunized groups of 6 melanoma patients with GD3-KLH or GD3-L-KLH conjugates containing 30 mu g of ganglioside plus 100 mu g of QS-21 at 0, 1, 2, 3, 7 and 19 weeks. Prior to vaccination, no serological reactivity against GD3 or CD3-L was detecte d. After immunization, IgM and IgG antibodies were detected against both GD 3 and GD3-L in the GD3-L group exclusively, The GD3-L-KLH vaccine induced I gM titers against GD3-L of 1:40-1/1,280 in all patients and IgG titers of 1 /160-1/1,280 in 4 patients. These antibodies also strongly cross-reacted wi th GD3, ELISA reactivity was confirmed by immune thin-layer chromatography on GD3 and melanoma extracts. Sera obtained from 4 of these 6 patients show ed cell surface reactivity by FAGS and from 2 showed strong cell surface re activity by immune adherence (IA) assay and complement lysis against the GD 3 positive cell line SK-Mel-28. (C) 2000 Wiley-Liss, Inc.