Serological evaluation of melanoma patients in a phase I/II trial of vaccinia melanoma oncolysate (VMO) immunotherapy.

Vaccinia melanoma oncolysates (VMO) were tested in a Southeastern Cancer Study Group (SECSG)-sponsored phase I/II multiinstitutional trial. Forty-eight patients with stage I or II disease were placed on study at six different dose levels of VMO and two different dose schedules, immediate or delayed. Patients' sera, obtained before treatment and every 3 months following initiation of treatment, were tested for antimelanoma antibodies using a Staphylococcus protein A (SpA) assay. Pretreatment sera were negative in 46 of 47 patients, and only two of 19 patients on delayed treatment developed reactivity by 6 months. However, 13 of 23 on immediate treatment developed reactivity, including eight of eight at the higher doses (1.5 and 2.0 mg). Neither anti-HLA antibody tested by a standard microcytotoxicity assay nor circulating immune complexes measured by both Clq and conglutinin binding assays were produced as a result of the immunization. The demonstration of immunogenicity of VMO at the 2 mg dose and immediate schedule supported the rationale for the use of this dose and schedule for the ongoing second phase Ia/Ib trial and for the future phase III randomized prospective study.

A Southeastern Cancer Study Group phase I/II trial with vaccinia melanoma oncolysates.

Vaccinia melanoma oncolysates (VMO) were tested in a Southeastern Cancer Study Group (SECSG) Phase I/II trial. Forty-eight patients with high-risk Stage I or pathologic Stage II disease were placed on study at six different dose levels and two different treatment regimens. Patients were monitored for toxicity to the VMO after each injection. Patients' sera were tested for anti-human melanoma reactivity with the Staphylococcus Protein A (SpA) assay. Toxicity was minimal at all doses tested. In only 2 of 19 patients on delayed treatment did reactivity develop in the SpA assay by 6 months. However, 13 of 23 patients on immediate treatment showed reactivity, including 8 of 8 at the two highest doses. Since the VMO appears to be safe at all of the doses tested, and because of the immunogenicity of the VMO at the higher doses as demonstrated by the SpA assay, the 2-mg dose level, for immediate treatment, was chosen for use in future trials.