These research results provide an overview of patient response in a clinical research program evaluating treatment of pediatric and adult leukaemia patients with experimental CAR genetically engineered T cells.

A series of treatment cohorts were included in the analysis, including pediatric and adult patients with high-risk, treatment-resistant acute lymphocytic leukaemia and adult patients with advanced relapsed and/or treatment-resistant chronic lymphocytic leukaemia.

The focus of this research effort was to understand how the engineered cells responded in patients with time, and how that response correlated with anti-leukaemia activity.

To accurately estimate the quantity, lifespan, and activity of the engineered cells in the patients, researchers developed a number of highly accurate tests.

The  researchers observed that those patients with the greatest expansion of T cells (above 5% of the total of all of their T cells) were very likely to achieve complete response; those with less robust, but still detectable, cell expansion were partial responders; and those who had no detectable T cell expansion did not respond to treatment. In complete responders, the engineered T cells were usually detectable many months after the infusion and continued to show functional activity in the body.

“These new and expanded data provide significant proof that T cells engineered to express cancer-targeting chimeric antigen receptors not only work, but work dramatically and in a sustained manner in patients with relapsed, treatment-resistant leukaemia, and further demonstrate the potential of this approach to help these patients achieve complete response,” said study author Michael Kalos, PhD, of the University of Pennsylvania Perelman School of Medicine in Philadelphia. “Further, our results show that we can potentially measure and track the activity of these engineered cells in the body as a way to monitor treatment, an exciting finding considering that this treatment is often the last hope for these patients.”

Source: ASH