Laurent Camille, Syrykh Charlotte, Hamon Maxime, Adélaïde José, Guille Arnaud, Escudié Frederic, Jalowicki Gael, Fina Frederic, Bardet Alexandre, Mescam Lenaïg, Molina Thierry J, Dartigues Peggy, Parrens Marie, Sujobert Pierre, Besson Caroline, Birnbaum Daniel, Xerri Luc
Department of Pathology, Cancer University Institute of Toulouse, CHU de Toulouse.
INSERM, U1037, Research Center In Cancer of Toulouse, laboratoire d'excellence TOUCAN, Toulouse.
Am J Surg Pathol. 2022 Jun 1;46(6):742-753. doi: 10.1097/PAS.0000000000001834. Epub 2021 Nov 18.
Despite the impressive efficacy of chimeric antigen receptor (CAR) T-cell therapy (CART) in B-cell non-Hodgkin lymphomas, durable responses are uncommon. The histopathologic and molecular features associated with treatment failure are still largely unknown. Therefore, we have analyzed 19 sequential tumor samples from 9 patients, prior anti-CD19 CART (pre-CART) and at relapse (post-CART), using immunohistochemistry, fluorescence in situ hybridization, array comparative genomic hybridization, next-generation DNA and RNA sequencing, and genome-scale DNA methylation. The initial diagnosis was diffuse large B-cell lymphoma (n=6), double-hit high-grade B-cell lymphoma (n=1), and Burkitt lymphoma (n=2). Histopathologic features were mostly retained at relapse in 7/9 patients, except the frequent loss of 1 or several B-cell markers. The remaining 2 cases (1 diffuse large B-cell lymphoma and 1 Burkitt lymphoma) displayed a dramatic phenotypic shift in post-CART tumors, with the drastic downfall of B-cell markers and emergence of T-cell or histiocytic markers, despite the persistence of identical clonal immunoglobulin gene rearrangements. The post-CART tumor with aberrant T-cell phenotype showed reduced mRNA expression of most B-cell genes with increased methylation of their promoter. Fluorescence in situ hybridization and comparative genomic hybridization showed global stability of chromosomal alterations in all paired samples, including 17p/TP53 deletions. New pathogenic variants acquired in post-CART samples included mutations triggering the PI3K pathway (PIK3R1, PIK3R2, PIK3C2G) or associated with tumor aggressiveness (KRAS, INPP4B, SF3B1, SYNE1, TBL1XR1). These results indicate that CART-resistant B-cell non-Hodgkin lymphomas display genetic remodeling, which may result in profound dysregulation of B-cell differentiation. Acquired mutations in the PI3K and KRAS pathways suggest that some targeted therapies could be useful to overcome CART resistance.
尽管嵌合抗原受体（CAR）T细胞疗法（CART）在B细胞非霍奇金淋巴瘤中疗效显著，但持久缓解并不常见。与治疗失败相关的组织病理学和分子特征仍 largely 未知。因此，我们使用免疫组织化学、荧光原位杂交、阵列比较基因组杂交、下一代DNA和RNA测序以及全基因组DNA甲基化分析了9例患者的19个连续肿瘤样本，包括抗CD19 CART治疗前（pre-CART）和复发时（post-CART）的样本。初始诊断为弥漫性大B细胞淋巴瘤（n = 6）、双打击高级别B细胞淋巴瘤（n = 1）和伯基特淋巴瘤（n = 2）。7/9的患者在复发时组织病理学特征大多保留，但经常有1种或几种B细胞标志物缺失。其余2例（1例弥漫性大B细胞淋巴瘤和1例伯基特淋巴瘤）在CART治疗后的肿瘤中表现出显著的表型转变，尽管克隆性免疫球蛋白基因重排相同，但B细胞标志物急剧下降，T细胞或组织细胞标志物出现。具有异常T细胞表型的CART治疗后肿瘤显示大多数B细胞基因的mRNA表达降低，其启动子甲基化增加。荧光原位杂交和比较基因组杂交显示所有配对样本中染色体改变总体稳定，包括17p/TP53缺失。CART治疗后样本中获得的新的致病变异包括触发PI3K途径的突变（PIK3R1、PIK3R2、PIK3C2G）或与肿瘤侵袭性相关的突变（KRAS、INPP4B、SF3B1、SYNE1、TBL1XR1）。这些结果表明，对CART耐药的B细胞非霍奇金淋巴瘤表现出基因重塑，这可能导致B细胞分化的严重失调。PI3K和KRAS途径中的获得性突变表明，一些靶向治疗可能有助于克服CART耐药性。
