Room: Davidson Ballroom A
Purpose: Cancer-specific antigens are a promising target of immunotherapy approaches for cancer treatments, but rely on a sufficient expression of the target-antigen. This study investigates the expression of the carcinoembryonic antigen (CEA) on the surface of lung cancer cells under irradiation in vitro.
Methods: Human lung carcinoma cells A549 were treated and expression of CEA on the cell surface measured using flow cytometry 3 hours, 24 hours and 72 hours after irradiation at 2Gy, 6Gy, 10Gy, and 20Gy. Cell viability was stained using propidium iodide and only viable cells analyzed regarding CEA expression, measured as percentage of CEA-positive cells.
Results: For 24 hours and 72 hours post irradiation at Stereotactic Body Radiotherapy (SBRT) doses of 6Gy and 10Gy, the increase of CEA-positive cells in percentage points was between 5 and 8. The expression was highest after 20 Gy showing an increase of 12 and 17 percent points after 24 and 72 hours, respectively. Overall, an increase in CEA-expression was observed for both increasing radiation dose and time. Overexpression of CEA was further confirmed by doubling in mean fluorescent intensity after 20Gy and 10Gy for 24 and 72 hours post irradiation, respectively.
Conclusion: This experiment shows an increase in CEA-expression on a human lung carcinoma following irradiation. We observed increase in expression with increasing radiation dose and in a time dependent manner up to 72 hours post irradiation. This result demonstrates that CEA may be a promising target for immunotherapy following irradiation. The results also indicate that the timing of immunotherapy targeting CEA should take the time after which this is administered into consideration.