The Activity of TroVax® Versus Placebo in Relapsed Asymptomatic Ovarian Cancer

A significant number of patients with advanced ovarian cancer develop a "CA-125 relapse" without clinical symptoms and with a low volume disease on the CT scan. For this group of patients, no survival benefit has been demonstrated from early chemotherapy treatment and, on average, the time to start of chemotherapy is 5 months. Such patients could benefit from immunotherapy and the time to chemotherapy could potentially be prolonged. Multiple immunotherapy agents, such as anti-CA-125 antibodies and various vaccines, have been tested and, although there is plenty of evidence of immune response, this has not translated to a definitive clinical benefit and is not recommended in clinical practice 5T4 appears to be highly expressed in ovarian cancer and correlates with more advanced stage of disease and poorly differentiated tumours. TroVax®, the vaccine targeting 5T4, has an extensive record of safety and efficacy in humans and vaccination in patients with colorectal, renal, and prostate cancer resulted in immune cellular and humoral responses and signs of clinical benefit. We propose a trial of TroVax® vaccination in patients with CA-125-relapsed asymptomatic ovarian cancer to assess the clinical efficacy and immunological responses as outlined in this protocol. To allow for capture of any delayed response to immunotherapy, patients who progress on RECIST 1.1 criteria and who do not experience toxicity from treatment will continue on the vaccine/placebo injection until repeat imaging at 8 weeks in order for immune-related response criteria (irRC) to be evaluated in addition to RECIST 1.1 criteria (these patients as a standard of care would not receive any other therapeutic intervention).