Vaccination with a Bivalent GM 2 and GD 2 Ganglioside Conjugate Vaccine : A Trial Comparing Doses of GD 2-Keyhole Limpet Hemocyanin 1

Immunization with GMK vaccine (G M2 ganglioside conjugated to keyhole limpet hemocyanin mixed with QS-21 adjuvant) induces anti-GM2 antibodies in close to 100% of patients. We found previously that anti-GD2 antibodies could be induced in some patients using GD2-keyhole limpet hemocyanin1 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 GD2; 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 mg of GM2) 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 mg of GD2). Anti-G M2 IgM or IgG were induced in 97% of patients. The dose of GDK did not affect the anti-GM2 response, although at the highest GDK dose level, 3 of 7 patients did not make anti-GM2 IgG. GDK was less immunogenic; overall 45% of patients developed either IgM or IgG against GD2. At GDK doses of 30 or 70 mg, 8 of 11 patients (73%) made either IgM or IgG anti-GD2 antibodies. We conclude that both GMK and GDK vaccines can induce antibodies against G M2 and GD2 in a majority of patients and are safe. The optimal dose of GDK appears to be either 30 or 70mg when administered with GMK vaccine. INTRODUCTION Gangliosides expressed on melanoma are attractive targets for immunotherapy. They are abundantly expressed, are not down-regulated when bound by antibody, do not require HLA molecule coexpression for the immune system to react to them, and may play an important role in melanoma-cell adhesion. In addition, it is clear that patients with melanoma can generate antibodies against ganglioside antigens (1–3). Among the gangliosides expressed by human melanomas, G M2 appears to be the most immunogenic. Immunization with G M2 and BCG adjuvant induced anti-GM2 IgM in more than 85% of patients, and the presence of either vaccine-induced or natural antibodies against GM2 correlated with an improved relapse-free survival (4). Subsequent studies showed that immunization with G M2 conjugated to KLH and mixed with QS-21 (5, 6) adjuvant (GMK vaccine) induced anti-G M2 IgM and IgG in close to 100% of patients (3, 7). On the basis of these observations, we determined that GMK vaccine resulted in optimal immunogenicity at a GM2 dose of 30mg. Because not all melanomas express G M2 (8), it seems likely that a maximally effective ganglioside vaccine will need to include multiple gangliosides. G D2 ganglioside is expressed in many melanomas and sarcomas, and monoclonal antibodies against GD2 can induce antitumor effects in patients with melanoma or neuroblastoma. Although antibodies against G D2 can be induced by immunizing patients with G D2-KLH plus QS-21 (9), the optimal GD2 dose has not been determined, and it is not known whether a bivalent ganglioside vaccine can induce antibodies against both G M2 and GD2. We carried out a trial using a mixed ganglioside conjugate vaccine consisting of both G M2-KLH and GD2-KLH with the adjuvant QS-21. GM2-KLH was administered at a fixed dose of 30 mg of GM2/immunization with one of five GD2-KLH doses. The primary goals were to assess the anti-G M2 antibody responses induced, determine which G D2-KLH doses induced anti-GD2 antibodies, and to determine whether this mixed ganglioside vaccine was safe. MATERIALS AND METHODS