CMB-305

Preclinical data suggest that a "prime-boost" vaccine regimen using a target-expressing lentiviral vector for priming, followed by a recombinant protein boost, may be effective against cancer; however, this strategy has not been evaluated in a clinical setting. CMB305 is a prime-boost vaccine designed to induce a broad anti-NY-ESO-1 immune response. It is composed of LV305, which is an NY-ESO-1 expressing lentiviral vector, and G305, a recombinant adjuvanted NY-ESO-1 protein. This multicenter phase 1b, first-in-human trial evaluated CMB305 in patients with NY-ESO-1 expressing solid tumors. Safety was examined in a 3 + 3 dose-escalation design, followed by an expansion with CMB305 alone or in a combination with either oral metronomic cyclophosphamide or intratumoral injections of a toll-like receptor agonist (glucopyranosyl lipid A). Of the 79 patients who enrolled, 81.0% had sarcomas, 86.1% had metastatic disease, and 57.0% had progressive disease at study entry. The most common adverse events were fatigue (34.2%), nausea (26.6%), and injection-site pain (24.1%). In patients with soft tissue sarcomas, a disease control rate of 61.9% and an overall survival of 26.2 months (95% CI, 22.1-NA) were observed. CMB305 induced anti-NY-ESO-1 antibody and T-cell responses in 62.9% and 47.4% of patients, respectively. This is the first trial to test a prime-boost vaccine regimen in patients with advanced cancer. This approach is feasible, can be delivered safely, and with evidence of immune response as well as suggestion of clinical benefit.

Synovial Sarcoma (SS) and Myxoid Round Cell Liposarcoma (MRCL) are devastating sarcoma subtypes with few treatment options and poor outcomes in the advanced setting. However, both these diseases may be ideal for novel immunotherapies targeting the cancer-testis antigen, NY-ESO-1.

In this review, we discuss the novel NY-ESO-1 targeted vaccine regimen, CMB305. This regimen uses a unique integration-deficient, dendritic-cell targeting lentiviral vector from the ZVex® platform, LV305, in order to prime NY-ESO-1 specific T cells. LV305 has single agent activity, and, in one case, caused a durable partial response in a refractory SS patient. CMB305 also includes a boost from a NY-ESO-1 protein vaccine given along with a potent toll-like-4 receptor agonist, glycopyranosyl lipid A. CMB305 induces NY-ESO-1 specific T cell responses in both SS and MRC patients and these patients had excellent overall survival (OS) outcomes in the initial phase I study.

CMB305 is a therapeutic vaccine regimen targeting NY-ESO-1 based on the lentiviral vaccine vector, LV305. Phase I studies have proven this vaccine is active immunologically. Data suggesting this vaccine may improve OS for SS and MRCL patients is exciting but early, and on-going work is testing the impact of CMB305 on patient outcomes.