Elios Therapeutics Phase IIb Personalized Vaccine Study Yields Positive Top-Line Results

NEW YORK – Elios Therapeutics reported positive top-line results from a Phase IIb study involving its personalized vaccine in patients with advanced, resected melanoma. 

The company focuses on the development of autologous, particle-delivered, dendritic cell cancer vaccines, and its lead candid is a tumor lysate, particle-loaded, dendritic cell (TLPLDC) vaccine. In a statement, Elios explained that its lead vaccine is personalized in that it is made from a patient's blood and tumor, so that it contains the tumor's unique antigenic profile. Once the personalized vaccine is administered, it is designed to elicit an innate and adaptive immune response by activating T cells and priming the immune system to recognize and destroy cells with tumor-specific antigens and mutations. 

The Phase IIb study randomized 144 Stage III/IV resected melanoma patients to receive either the TLPLDC vaccine or placebo and evaluated the impact on recurrence. Researchers evaluated outcomes in the overall intent-to-treat population, which included patients who were never or incompletely vaccinated, and looked at outcomes only in patients who completed the full vaccine series. 

In all 144 patients, Elios reported a 24-month disease recurrence rate of 54 percent in the vaccine arm compared to 66 percent in the placebo arm. This represents an 18 percent reduction in the relative risk of melanoma recurrence, which the company characterized in a statement as "clinically meaningful," though not statistically significant. 

In patients who received the full vaccine series, Elios reported a recurrence rate of 29 percent in the vaccine arm versus 56 percent in the placebo arm, a 50 percent reduction in the relative risk of disease recurrence that was statistically significant.

An independent data safety monitoring board didn't flag any safety concerns, since only one-third of patients experienced an adverse event, which were mostly not serious. Initial assessment of 36-month follow-up data of all patients suggests that some may experience benefit from the vaccine beyond 24 months. As a result, the monitoring board recommended that the trial continue as designed to get data on the impact of the vaccine on disease-free survival and overall survival, which Elios anticipates by June 2020.

The company will present more detailed results from the Phase IIb trial at an upcoming medical meeting and will advance the TLPLDC vaccine into Phase III studies. "This is the first positive Phase IIb study of a personalized cancer vaccine in patients with high-risk melanoma," Elios CEO Buddy Long said in a statement. "We believe the results from this trial support advancing the TLPLDC clinical program to a Phase III trial."

Elios is studying the TLPLCD vaccine as a standalone personalized vaccine, as well as in combination with checkpoint inhibitors in late-stage melanoma patients.