PrimeVax Receives FDA’s OK to Use Dengue Virus for Cancer Treatment

The U.S. Food and Drug Administration (FDA) has approved three clinical studies testing PrimeVax Immuno-Oncology’s investigational approach using dendritic cells and dengue virus for cancer treatment.

The investigational new drug (IND) application is for patients with melanoma (skin cancer) who have failed prior immune checkpoint inhibitors. Hospital sites are being prepared to start dosing patients with the therapies.

“Today, I am proud to report that we have successfully built [the] dengue virus into our clinical design, and have gained alignment with FDA on this novel therapeutic approach,” Tony Chen, PrimeVax’s CEO, said in a press release.

PrimeVax is developing a multi-mechanism treatment strategy that takes advantage of the body’s  immune system to fight malignant cells. It combines immune cells called stimulatory dendritic cells with the dengue virus to trigger a broader and stronger immune response against resistant cancer cells.

The company established an exclusive agreement with the U.S. Army to use a specific dengue virus strain (dengue virus-1 #45AZ5) to treat cancer in January 2019. This dengue strain has a zero mortality rate and is well-tolerated.

“Working with the U.S. Army is a well-considered strategy; their history of managing dengue symptoms and safety data make this virus candidate a reasonable choice for cancer patients,” said Bernard A. Fox, PhD, Harder Family Chair for cancer research at Oregon’s Earle A. Chiles Research Institute.

By using the Army’s dengue virus, researchers aim to induce a systemic fever in a controlled manner. This will trigger a common immune response and create a pro-inflammatory status in patients, activating the therapeutic dendritic cells to specifically target the malignant cells.

“The immune changes induced by our therapy have synergy potential with checkpoint inhibitors and other standard-of-care therapies,” the company states on its webpage.

To evaluate the safety and effectiveness of this strategy, the company is launching three Phase 1 clinical trials in patients with advanced melanoma. They will test the effects of dendritic cells alone (NCT03803397), dengue virus alone (NCT03989895), and a combination of the two approaches (NCT03990493).

Each study is expected to include 10 patients, with results expected during the third trimester of 2021.

The main goal is to identify the best treatment protocol and potential safety issues. Researchers will also evaluate the anti-cancer activity of the different approaches by determining response and survival rates.

According to investigators at PrimeVax, results from these trials “may unlock some of the secrets of tumor immune evasion that have been obstacles to achieving better clinical responses.”