Bristol Myers Squibb, San Diego, CA.
Blood Adv. 2021 Apr 13;5(7):2027-2039. doi: 10.1182/bloodadvances.2020003431.
CC-122 is a next-generation cereblon E3 ligase-modulating agent that has demonstrated promising clinical efficacy in patients with relapsed or refractory diffuse large B-cell lymphoma (R/R DLBCL). Mechanistically, CC-122 induces the degradation of IKZF1/3, leading to T-cell activation and robust cell-autonomous killing in DLBCL. We report a genome-wide CRISPR/Cas9 screening for CC-122 in a DLBCL cell line SU-DHL-4 with follow-up mechanistic characterization in 6 DLBCL cell lines to identify genes regulating the response to CC-122. Top-ranked CC-122 resistance genes encode, not only well-defined members or regulators of the CUL4/DDB1/RBX1/CRBN E3 ubiquitin ligase complex, but also key components of signaling and transcriptional networks that have not been shown to modulate the response to cereblon modulators. Ablation of CYLD, NFKBIA, TRAF2, or TRAF3 induces hyperactivation of the canonical and/or noncanonical NF-κB pathways and subsequently diminishes CC-122-induced apoptosis in 5 of 6 DLBCL cell lines. Depletion of KCTD5, the substrate adaptor of the CUL3/RBX1/KCTD5 ubiquitin ligase complex, promotes the stabilization of its cognate substrate, GNG5, resulting in CC-122 resistance in HT, SU-DHL-4, and WSU-DLCL2. Furthermore, knockout of AMBRA1 renders resistance to CC-122 in SU-DHL-4 and U-2932, whereas knockout of RFX7 leads to resistance specifically in SU-DHL-4. The ubiquitous and cell line-specific mechanisms of CC-122 resistance in DLBCL cell lines revealed in this work pinpoint genetic alternations that are potentially associated with clinical resistance in patients and facilitate the development of biomarker strategies for patient stratification, which may improve clinical outcomes of patients with R/R DLBCL.
CC-122 是一种新一代的 cereblon E3 连接酶调节剂，在复发或难治性弥漫性大 B 细胞淋巴瘤（R/R DLBCL）患者中显示出有前景的临床疗效。在机制上，CC-122 诱导 IKZF1/3 的降解，导致 T 细胞激活和 DLBCL 中的强大细胞自主杀伤。我们报告了在 DLBCL 细胞系 SU-DHL-4 中进行的 CC-122 的全基因组 CRISPR/Cas9 筛选，并在 6 个 DLBCL 细胞系中进行了后续的机制特征分析，以确定调节对 CC-122 反应的基因。排名最高的 CC-122 耐药基因编码的不仅是 CUL4/DDB1/RBX1/CRBN E3 泛素连接酶复合物的明确定义成员或调节剂，而且是信号和转录网络的关键组成部分，这些成分尚未显示可调节 cereblon 调节剂的反应。CYLD、NFKBIA、TRAF2 或 TRAF3 的缺失会导致经典和/或非经典 NF-κB 途径的过度激活，随后会减少 6 个 DLBCL 细胞系中 CC-122 诱导的凋亡。CUL3/RBX1/KCTD5 泛素连接酶复合物的底物衔接蛋白 KCTD5 的耗尽会促进其同源底物 GNG5 的稳定，从而导致 HT、SU-DHL-4 和 WSU-DLCL2 对 CC-122 的耐药性。此外，AMBRA1 的敲除使 SU-DHL-4 和 U-2932 对 CC-122 产生耐药性，而 RFX7 的敲除则使 SU-DHL-4 对 CC-122 产生特异性耐药性。本研究揭示了 DLBCL 细胞系中 CC-122 耐药的普遍和细胞系特异性机制，确定了与患者临床耐药相关的潜在遗传改变，并促进了生物标志物策略的开发，以进行患者分层，这可能改善 R/R DLBCL 患者的临床结局。
