How a new PET agent could predict immunotherapy responses sooner
Stanford University researchers have made an imaging agent that detects activated T cells and could predict whether a patient will respond to immunotherapy within days of treatment.
Typically, it takes weeks to months to determine if a treatment is halting tumor growth. Earlier biomarkers for efficacy could not only streamline clinical trials, but could provide information about the biology of a therapy in patients, and enable physicians to adjust dosing and optimize treatment combinations in real time.
Positron emission tomography (PET) agents bound to small molecules have been used in cancer because they bind proliferating cells with active metabolic profiles. But PET has been of little use in immuno-oncology because the T cell reactive agents developed don’t distinguish metabolically active T cells from the metabolically active tumor cells they are trying to kill.
In a Journal of Clinical Investigation study published last month, Stanford University Professors Sanjiv Sam Gambhir, Ron Levy and colleagues described an OX40-based strategy to use PET to detect responses to immunotherapy by showing where and when activated T cells are present.
OX40 is a surface receptor expressed at high levels on activated T cells but not on cancer cells or non-active