慢性淋巴细胞白血病 (CLL) 细胞在淋巴结 (LN) 微环境中上调 Bcl-2 蛋白。通过 B 细胞受体、Toll 样受体和 CD40 信号联合作用，降低对 BCL-2 抑制剂 venetoclax 的敏感性。venetoclax加BTK抑制剂ibrutinib的有限治疗时间可导致深度缓解，但这种组合对LN相关信号的影响尚不完全清楚。因此，使用HOVON141 / VISION第2期临床试验中获得的样本进行分析。两个疗程的引导ibrutinib单药治疗导致循环CLL细胞中Bcl-2蛋白的表达下降。令人惊讶的是，在这个时间点，CD40诱导的venetoclax抵抗力被强烈减弱，CD40表达也被减少。由于CD40信号发生在CLL LN内，因此我们测试了各种可能影响CD40信号通路的LN相关信号。虽然BCR刺激只有轻微效果，但通过CpG刺激的TLR9刺激显着增加了CD40表达，并且通过诱导总体蛋白翻译，重置了ibrutinib治疗对venetoclax敏感性的影响。总之，这些发现确定了ibrutinib的一种新效应：打断TLR9诱导的CD40上调和促生存蛋白的翻译。这种机制有可能进一步抑制CLL细胞在LN微环境中对venetoclax的抵抗力的激活。 © 2023. The Author(s).

Chronic lymphocytic leukemia (CLL) cells upregulate Bcl-2 proteins within the lymph node (LN) microenvironment. Signaling via B-cell receptor, Toll-like receptors and CD40 collectively reduce sensitivity to the BCL-2 inhibitor venetoclax. Time-limited treatment with venetoclax plus the BTK-inhibitor ibrutinib results in deep remissions, but how this combination affects LN-related signaling is not yet completely clear. Therefore, samples obtained from the HOVON141/VISION phase 2 clinical trial were used to analyze this. Two cycles of lead-in ibrutinib monotherapy resulted in decreased protein expression of Bcl-2 proteins in circulating CLL cells. Strikingly, at this timepoint CD40-induced venetoclax resistance was strongly attenuated, as was expression of CD40. Since CD40 signaling occurs within the CLL LN, we tested various LN-related signals that could affect CD40 signaling. While BCR stimulation had only a minor effect, TLR9 stimulation via CpG led to significantly increased CD40 expression and importantly, reverted the effects of ibrutinib treatment on venetoclax sensitivity by inducing overall protein translation. Together, these findings identify a novel effect of ibrutinib: interruption of TLR9-induced CD40 upregulation and translation of pro-survival proteins. This mechanism may potentially further inhibit priming of CLL cells in the LN microenvironment for venetoclax resistance.© 2023. The Author(s).