Abstract 47P
Background
Radiotherapy (RT) and immunotherapy (IO) may have synergistic anti-tumor effect for treating metastatic non-small-cell lung cancer (mNSCLC). However, the optimal timing of RT in relevance to IO and whether it affects outcomes is unknown.
Methods
We conducted a retrospective study of all patients with mNSCLC treated with IO at our institution (2011–2022). Patients who received targeted therapy or prior concurrent chemoRT + durvalumab were excluded.
Results
In this cohort of 225 patients, 56% were male, 82% were Caucasian. The median age was 68 (44–95). The histology was predominantly adenocarcinoma (79%). The most common metastatic sites were bone (41%) followed by CNS (25%). 56% patients received RT before or during IO. 27% never received RT. 17% received RT after discontinuation of IO. Pembrolizumab was the most used IO (78%), followed by Nivolumab (14%) and Atezolizumab (12%). Most patients received IO in the frontline (60%). We observed no statistical difference in PFS, OS, or development of immune-related adverse events in patients who received RT before or during IO compared to patients without RT (PFS: 5.9 vs. 5.5 months, p = 0.66; OS: 16.9 vs. 13.1 months, p = 0.84; irAE: 26.2% vs. 34.4%, p = 0.24). Patients with RT were divided into four groups by the timing of RT related to IO: >12 months prior to IO (N = 29), between 1 and 12 months prior to IO (N = 39), <1 month prior to IO (N = 30), after IO initiation (N = 28). The median PFS (months) of the above groups were 4.3, 12.6, 4.2, and 5.1, respectively, and the median OS (months) were 16.5, 25, 13.9, and 16, respectively. We found significantly higher PFS in patients who received RT between 1 and 12 months before IO, compared with those received RT<1 month before IO (12.6 vs. 4.2 months, p = 0.005, HR 0.46, 95% CI 0.26–0.83), or compared with patients without RT (12.6 vs. 5.5 months, p = 0.0197, HR 0.56, 95% CI 0.36–0.89). This trend was sustained in the OS analysis (25 vs. 13.9 months, p = 0.08; 25 vs. 13.1 months, p = 0.18).
Conclusions
We observed statistically significant and clinically meaningful PFS benefits of IO in patients with mNSCLC who received RT between 1 and 12 months prior to IO. There is a positive trend for OS benefit, although not statistically significant. These findings need to be verified in a larger cohort.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.