Researchers affiliated with the UK Children’s Cancer Study Group have reported that a vaccine known as Onyvax-105 (105AD7 ) elicits an immune response in patients with osteosarcoma. The details of this report appeared in the British Medical Journal.[1]

Osteosarcoma is a disease of younger individuals that is treated with surgery, radiation and chemotherapy. However, despite optimal therapy, the majority of patients with advanced disease ultimately relapse. Onyvax-105 is an anti-idiotypic monoclonal antibody that mimics the tumor associated antigen 791/gp72, which was developed by Onyvax Limited.[2] A previous randomized study in patients with advanced colorectal cancer comparing Onyvax-105 to placebo failed to show efficacy, a result attributed to a high tumor burden.[3]

In the UK study, vaccine was administered to 31 pediatric and young adult patients with osteosarcoma after completion of chemotherapy. Significant T-cell responses were observed in 71% of patients. Over 50% of patients showed antigen-specific gamma interferon secretion, and 31% showed an antibody response. The vaccine was described as well tolerated. They also reported that two patients with possible clinical responses continued immunization for two years and are disease-free for over 5 years. The authors propose to carry out a randomized trial to determine if this vaccine is effective.

Comments: It is difficult to know from this trial if Onyvax-105 will be effective in osteosarcoma or other diseases. This vaccine will need to be tested in randomized trials in patients with minimal residual disease and a high probability of relapse.

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