Blood-based TMB detection and dynamic monitor in local advanced non-small cell lung cancer (NSCLC) patients.

Abstract

e20039 Background: TMB detection has been recommended by NCCN guidelines as an effective biomarker for immunotherapy of advanced non-small cell lung cancer(NSCLC). Blood based TMB(b-TMB) detection is considered to be able to predict the efficacy of immunotherapy in patients with advanced NSCLC. Concurrent chemoradiotherapy is the standard treatment for locally advanced NSCLC(LA-NSCLC) and subsequent consolidated immunotherapy has become the standard treatment. Therefore, the b-TMB status and dynamic changes in patients with LA-NSCLC are particularly important. Methods: We enrolled 7 patients with LA-NSCLC, each receiving 60Gy chest radiotherapy and docetaxel plus cisplatin weekly regimen chemotherapy. We tested the TMB by next-generation sequencing with 520 genes panal in tissues and blood of each patient at baseline. In addition, b-TMB was measured dynamically in 6 patients at different time points during chemoradiotherapy, each two patients were tested for over four times within one week of treatment, two weeks later and four weeks later. Results: As shown in the table, the baseline b-TMB matched the tissue TMB. Except for one ALK fusion patient, the positive rate of b-TMB was 100% and the Spearman correlation value was 0.899(p = 0.015). B-TMB fluctuated but did not change much within first two weeks of concurrent chemoradiotherapy. After the fourth week of chemoradiotherapy, b-TMB significantly decreased in all patient. Conclusions: In patients with LA-NSCLC, b-TMB is a reliable biomarker, which is likely to change in the later stage of concurrent chemoradiotherapy. Its dynamic monitor will help to distinguish which patients may benefit from consolidated immunotherapy after concurrent chemoradiotherapy. [Table: see text]