Medical Researchers Pen Letter to FDA on T-Cell Significance

A group of researchers sent a letter to the Food and Drug Administration’s (FDA) Commissioner Robert Califf, MD, and Director of the Center for Biologics Evaluation and Research Peter Marks, MD, PhD, on Thursday to lend their support behind measuring T-cells for COVID-19 vaccine clinical trials.

Thus far, vaccine data has focused on measuring neutralizing antibodies and not T-cells, which to some, seems to be a limitation in understanding the whole immunity puzzle.

"The limited study of T cells in SARS-CoV-2 research is impeding our ability to inform policies related to emerging variants and long-term immune protection after Ab titers have appropriately declined following infection and/or vaccination. The focus on Abs stems in part from the ease of their quantitative measurement, making them more convenient to include in research and clinical trials," the letter to the FDA states.

“The neutralizing antibodies we are looking for only bind to a very small part on the tip of the spike protein,” Adaptive Biotechnologies Cofounder and Chief Scientific Officer Harlan Robins, PhD, who was a cosigner of the letter and said in a recent interview with Contagion. “Whereas, the T-cell response is spread out across the entire genome.”

Seattle-based Adaptive Biotechnologies developed technology around simplifying T-cell testing at scale. For example, the company has developed their T-Detect test to determine a recent or past COVID-19 infection. This test has received a Food and Drug Administration Emergency Use Authorization. The also have another test, immunoSEQ T-MAP COVID, which provides researchers with the ability to determine past SARS-CoV-2-specific immune response in research samples and track responses longitudinally.

Adaptive’s Robins discussed this technology and the value of measuring these protector cells.

The letter goes on to stress the need to collect data and advocate for updating clinical trial protocols. "We need a concerted effort to collect data on the broad immune response beyond Abs, especially for our most vulnerable, to best inform public health strategies and federal policy decisions. We need clinical trial protocols that include investigations of the full range of adaptive immune responses in order to ensure that countermeasures keep pace with an evolving virus and lay the foundation for responses to future epidemics and pandemics."