SillaJen, Inc., a biotechnology company focused on developing oncolytic immunotherapies, announced the results of a Phase Ib trial for refractory, metastatic colorectal cancer patients treated with their leading treatment, Pexa-Vec. The study entitled “Phase Ib trial of biweekly intravenous Pexa-Vec (JX-594), an oncolytic and immunotherapeutic vaccinia virus in colorectal cancer” published in the journal Molecular Therapy represents the first of its kind where patients were administered with multiple intravenous injections of an oncolytic vaccinia (vaccination with vaccinia virus was the strategy responsible for the successful eradication of smallpox (variola)).
Oncolytic immunotherapy is based on a strategy where viruses are re-enginereed to selectively multiply inside tumor cells and release potent cytokines that activate immune system’s “soldiers” to direct their attack against tumor cells, resulting in tumor death. Pexa-Vec is specifically designed to induce tumor cells lysis, inhibit vascularization in the tumor (this enables tumor expansion, local invasion, and dissemination) and induce a long-term anti-tumor immune response. To this end, Pexa-Vec was engineered to express GM-CSF, a white blood cell growth factor that activates a systemic immune response directed against tumor cells.
15 patients with treatment-refractory colorectal cancer were treated every 14 days with intravenous injections of Pexa-Vec. Infusions at three escalating doses were administered to nine patients. Patients reported no serious adverse effects related to Pexa-Vec treatment.
Eun Sang Moon, chief executive officer of SillaJen commented, “While we have reported dose-dependent antitumor activity in the past with Pexa-Vec, we believe that demonstrating feasibility of administering Pexa-Vec by multiple intravenous infusions broadens the tumor types that can be targeted with this novel oncolytic immunotherapy. The data published today show excellent tolerability despite multiple administrations indicating the drug’s ability to be administered systemically at regular intervals which may allow the targeting of systemic disease more effectively.”
Caroline Breitbach, Ph.D., vice president of clinical and translational research at SillaJen added, “Pexa-Vec has been shown to target and kill tumor cells through multiple mechanisms of action. The data published today further strengthen the growing body of Pexa-Vec safety and mechanism of action data, particularly relating to systemic Pexa-Vec administration.”