Published in the journal Oncoimmunology, the findings showed that the peptide called PD1-Vaxx, a first checkpoint inhibitor vaccine, was safe and effective in a colon cancer syngeneic animal model. The researchers say the vaccine produced polyclonal antibodies that inhibit the programmed cell death receptor, PD-1, on cancer cells. The vaccine mimics the action of the PD-1 inhibitor nivolumab (Opdivo®), but it avoids triggering the innate and acquired resistance associated with that and related agents, they add.
The study found that PD1-Vaxx was effective in inhibiting tumor growth. It was even more effective when used in combination with a second therapeutic peptide vaccine, one that targets two sites on the HER-2 receptor on colon cancer cells. The combination treatment produced complete responses in nine of 10 animals. That vaccine, called B-Vaxx, was developed earlier by the same research team.
“Our study is important for two key reasons,” says first author and vaccine developer Pravin T.P. Kaumaya, PhD, a member of the OSUCCC – James Translational Therapeutics Research Program and a professor in Ohio State’s College of Medicine. “First, PD1-Vaxx activates both B- and T-cell functions to promote tumor clearance. Second, the treatment is targeted to block signaling pathways that are crucial for tumor growth and maintenance.
“By giving this vaccine in combination with an immunotherapy drug,” he explains, “we are supercharging and directing the immune system to target and kill cancer cells.”
In November 2020, the U.S. Food and Drug Administration (FDA) granted investigational new drug (IND) approval to Imugene for clinical testing of PD1-Vaxx, an important milestone in the research collaboration between Ohio State and Imugene.
A first-in-human, phase I clinical trial to test the vaccine was expected to open at the OSUCCC – James in 2021 for certain patients with non-small cell lung cancer. Additional U.S. sites may be added to the trial later.
“We are excited to begin testing of this vaccine in the United States to offer new hope to patients with lung and other cancers,” Kaumaya says.