ESTRO 2024 - Abstract Book

S1901

Clinical - Mixed sites, palliation

ESTRO 2024

Figure 1 : Final RA at last visit: patient-based analysis

RA at last visit showed 2 patients with complete remission (CR, 2%), 13 (13%) with partial remission (PR), 20 (20%) with stable disease (SD), 44 (45%) with progressive disease (PD) and 12 patients with mixed response (MR, 12%). Figure 2 shows an example of a patient with AR in a lymph node metastasis after RT.

Figure 2: Example of a 53-year-old male patient with metastatic malignant melanoma, first diagnosed in 2013. He showed tumor progression under ongoing ICI with Nivolumab (started in July 2020) with enlarged inguinal lymph nodes (LN), pulmonal metastasis and bone metastases in thoracic vertebrae (TV) 2 + 3. A: right inguinal LN in June 2020: 3cm, red arrow indicating LN metastasis, B: the same LN in October 2020: 5cm, C: LN shortly after radiotherapy of thoracic vertebrae 2-3, December 2020: 2,1cm, D: last control in February 2022: 0,5cm LN, no morphologic signs of disease. Immunotherapy was ended in February 2022, E: diagram of LN size (blue line) and time course, red bar = radiotherapy of TV 2+3 (October-November 2020, 30Gy in 10 fractions)

Conclusion:

This is the first analysis of AbE following concurrent RT for PD during ICI treatment in a large multicenter cohort. AR in all lesions occurred in approximately 20% of patients, which is in line with published literature. Our data suggests synergy between RT and ICI and serve as reference for designing prospective trials evaluating AbE.