Abstract 1907P
Background
Programmed cell death (PD-1) inhibitors with radiotherapy (RT) have emerged as a breakthrough therapy in the treatment of various cancer. However, the efficacy and adverse reaction is still unclear about the order of two treatment options. Furthermore, radiation pneumonitis (RP) is the most significant dose-limiting toxicity and is one major obstacle for thoracic radiotherapy. there is limited data on radiation pneumonitis (RP) with immunotherapy. Therefore, we assessed RP in different periods when radiotherapy and immunotherapy are combined.
Methods
Patients treated with thoracic radiotherapy and ≥ 1 dose of anti-PD1 drugs (nivolumab, pembrolizumab, toripalimab, camrelizumab and sintilimab) within 3 months were divided into two groups. Group A is patients treated with anti-PD1 drugs before or during thoracic radiotherapy, and the application after radiotherapy is defined group B. All the patients were evaluated to identify cases of ≥ grade 1 RP. The timing and incidence of RP was compared between two cohorts.
Results
In total, 41 (43%) of the 95 patients treated with thoracic radiotherapy who received anti-PD1 drugs developed ≥ grade 1 RP a median of 2.5 months after radiotherapy. More patients treated previous and concurrent RT developed RP than patients in group B (27/45 vs 14/50, 60% vs 28%, P = .01). Besides, the onset of RP among patients in group A was significantly shorter vs group B (2.0 vs 2.9 months; P = .05).
Conclusions
Our data suggest the application of anti-PD1 drugs before or during thoracic radiotherapy increases the incidence of radiation pneumonia. Furthermore, an accelerated onset of RP in patients treated previous and concurrent RT compared with subsequent RT. RP should be should get more attention when radiotherapy and immunotherapy are combined.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Xiangzhi Zhu.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.