2006P - Immune activation effect and survival of different irradiated sites in ES-SCLC patients treated with radioimmunotherapy: A real-world analysis

Background

Genetic heterogeneity between primary lesion and metastatic organs is the reason for different immunogenic cell death and persistent antitumor immune activity in different irradiated sites. Besides, considering the intratumor heterogeneity in subtypes of SCLC, the combination of immunotherapy and radiotherapy for different metastases may have significantly differences. Considering the limited data, we aimed to identify the greatest immune activation effect of different irradiated sites and survival analysis in extensive-stage small cell lung cancer (ES-SCLC) patients treated with immunotherapy concurrent with radiotherapy.

Methods

45 patients with ES-SCLC who had received radiation to a primary or metastatic solid tumor were enrolled. We collected overall survival time and blood cell counts including neutrophil, lymphocyte, monocyte, platelet in three time periods, before, during and after radiotherapy, and derived some blood index ratios including monocyte-to-lymphocyte ratio (MLR), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and systemic immune-inflammation index (SII). The delta-IBs were calculated as medio-IBs ÷ pre-IBs-1. We analyzed the changes before and during RT using Spearman rank correlation test, Kruskal-Wallis rank sum test, as well as logistic regression and survival analysis used for the survival analysis.

Results

In selected blood indexes, NLR, PLR and SII are correlated with different irradiated organs, and the medians of delta-NLR, delta-PLR and delta-SII were all the lowest in brain irradiated group during immunotherapy. In the multivariate analysis, only treatment stage was the independent prognostic factors for 9m OS. The median OS of the entire study cohort was 23.5months (95% CI, 10.1–36.9months). For the analysis of ICI stages, patients with second-line ICIs had a higher median OS time than those with first or third and more-line stages (OS: 36.9 vs 22.3 vs 16.1m; p = 0.001).

Conclusions

We hypothesised RT to brain has the strongest activation effect and survival compared with other organs in ES-SCLC during immunotherapy. And the second-line immunotherapy combined with radiotherapy achieved better curative effect.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

M. Wu.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.