簡介：TCR曲目在免疫反應的編排中起著關鍵作用。特別是已經提出減少治療前香農多樣性，增加克隆性和TCR收斂性以反映腫瘤微環境中抗原特異性T細胞的克隆擴增，以上這些被認為與更好的反應率、改善的無進展生存期(PFS)和總生存期(OS)相關。我們旨在探討NSCLC患者(PDL1)外周血中的上述TCR庫特征≥50%)在一線治療中用單藥pembrolizumab治療;並將它們與總體響應率(ORR)，改善的無進展生存期(PFS)和總生存期(OS)相關聯。Introduction:TCR repertoire plays a key role on the orchestration of the immune response. In particular, reduced pre-treatment Shannon diversity, increase clonality and increase convergence of TCRs have been suggested to reflect clonal expansion of antigen-specific T-cells in the tumour microenvironment. These are thought to be correlated with better response rate, improved progression free survival (PFS) and overall survival (OS). Here we aim to explore the above TCR repertoire features in peripheral blood of NSCLC patients (with PDL1≥50%) treated with single agent pembrolizumab in the first line setting; and correlate them with overall response rate (ORR), PFS and OS.

方法：我們前瞻性收集了48例接受一線pembrolizumab治療的非小歐細胞性肺癌患者的基線血液。從白細胞中提取高質量的DNA，並使用Oncomine TCR Beta SR分析(Thermo Fisher)進行TCR測序。計算每個個體的TCR克隆性和收斂性，並使用Kaplan-Meier曲線和生存統計與生存相關。進行多變量分析以控製可能影響TCR庫和結果(例如年齡，性別，ECOG，吸煙狀況和治療前中性粒細胞與淋巴細胞比率(NLR))關聯的其他變量。

Methods:We prospectively collected baseline blood from 48 NSCLC patients treated with first line pembrolizumab. High quality DNA was extracted from white blood cells and used for TCR sequencing using the Oncomine TCR Beta-SR Assay (Thermo Fisher). TCR clonality and convergence were calculated for each individual and correlated with survival using Kaplan-Meier curves and survival statistics. Multivariate analysis was carried out controlling for other variable that may influence the association of TCR repertoire and outcomes such as age, sex, ECOG, smoking status and pre-treatment neutrophil to lymphocyte ratio (NLR).

結果：:我們的數據僅對29例患者進行了至少6個月的隨訪。我們觀察到pembrolizumab有客觀反應的患者治療前TCR克隆性增加的趨勢，而Shannon多樣性顯著降低(P = 0.042)，收斂似乎並沒有影響我們隊列中的ORR。此外，治療前克隆數量減少(HR=0.54,95%CI 0.21-1.43，P=0.037)，香農多樣性降低(HR=0.52,95%CI 0.20-1.38，P=0.047)，均勻度降低(HR=0.41,95%CI 0.14-1.19，P=0.044)和ELVA克隆性(HR=2.45,95%CI 0.84-7.11，P=0.044)。減少而不是增加收斂與改善PFS的趨勢相關。這些參數都沒有與OS相關的靜態顯著性。

Results:Our data matured for 29 patients only with a follow-up of at least 6 months. We observed a trend towards increased pre-treatment TCR clonality in patients with objective response to pembrolizumab and statistically significant reduced Shannon diversity (P = 0.042). Convergence did not seem to affect ORR in our cohort. Moreover, there was a significantly longer PFS in patients with reduced number of pre-treatment clones (HR = 0.54, 95%CI 0.21-1.43, P = 0.037), reduced Shannon diversity (HR = 0.52, 95%CI 0.20-1.38, P = 0.047), reduced Evenness (HR = 0.41, 95%CI 0.14-1.19, P = 0.044) and eleva clonality(HR = 2.45, 95%CI 0.84-7.11, P = 0.044). Reduced rather than increased convergence was correlated with a trend towards improved PFS. None of these parameters were statically significant in relation to OS.

結論：治療前TCR克隆性增加和多樣性降低與ORR和PFS改善相關，但與pembrolizumab單藥治療高PD-L1的NSCLC患者無關。該隊列的進一步成熟將證明循環治療前TCR庫是否是免疫檢測點抑製的預後因素。

Conclusion:Increased pre-treatment TCR clonality and reduced diversity are associated with improved ORR and PFS, but not OS in NSCLC patients with high PD-L1 treated with pembrolizumab monotherapy. Further maturation of this cohort will demonstrate whether the circulating pre-treatment TCR repertoire is a prognostic factor for immunecheckpoint inhibition.