ESTRO 2024 - Abstract Book

S5165

Radiobiology - Immuno-radiobiology

ESTRO 2024

Figure 1: Dose response box and whisker plots for C3H tumors. The treatments were initiated when these tumors reached approximately 100 mm 3 in size. The figure shows the median time in days for the tumors to grow to the end point of 1000 mm 3 that is plotted against proton radiation (Gy). n = 8 – 11 mice per treatment group ; **p <0.01

Conclusion:

The C3H mammary carcinoma tumors is generally unresponsive to anti-CTLA-4 as a single therapy agent. An enhanced response was obtained when it was combined with either proton radiation or OXi4503 but not with hyperthermia. With increasing of tumor size at treatment, the benefit of combinational therapy decreases, indicating negative co-relation between tumor size and the resulting overall efficacy of the combination therapy. From the dose response plot (figure 1), it could be seen that the enhancement could only be seen when proton radiation overcomes a certain threshold of tumor damage prior to administration of anti-CTLA-4 treatment. Further investigations are being carried out to determine the mechanism underlying the observed results. Acknowledgement: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 955625 (Hyperboost; www.Hyperboost-h2020.eu) and a grant from the Danish Cancer Society.

Keywords: Proton therapy, Chemotherapy, Heat, Immunotherapy

References:

1. Chen DS, Mellman I. Oncology Meets Immunology: The Cancer-Immunity Cycle. Immunity. 2013 Jul 25;39(1):1– 10.