ESTRO 2021 Abstract Book

S138

ESTRO 2021

PET (FDG-PET) before CARTT and survival outcomes are reported. Results

In total 45 patients underwent an apheresis procedure. Fourteen of these patients (31.1%) did not receive bridging treatment, 19 (41.2%) underwent RT alone, 5 (11.1%) received ST alone (steroids or chemotherapy) and 7 (15.6%) received ST and RT (See table). RT was given on bulky tumor or burdensome lesions, in the majority of patients to a total dose of 20 Gy in 5 fractions (See figure). Eighty-one percent of patients had an infield response to RT. All patients who received RT alone had out of field progression, compared to 87% in patients who received RT and ST and 66% in patients after ST alone. Finally 41 patients (91.1%) received CARTT, while 3 patients did not due to rapid progression and no residual disease (1). The 1-year overall survival of patients who did not receive bridging treatment was 90%, compared to 74.1% in patients bridged with RT alone and 46.7% in patients treated with ST or combined treatment. 1- year progression free survival was 62.3% versus 48.9% and 40.0%, respectively. Conclusion Bridging the time between apheresis and infusion is a critical phase in CARTT. Selection of bridging treatment type is based on prior treatment, tumor load and symptoms. RT is a good alternative for ST in this heavily pre- treated patient population with a control rate of 81%. Given the high progression rate, close follow-up is needed during the bridging phase.