From the Human Oncology and Pathogenesis Program (E.W., X.M., B.H.D., A.P., S.X.L., J.B., S.J.H., C.E., D.C., H.C., M.S., O.A.-W.), the Leukemia Service (M.C.T., M.G., J.H.P., L.R., A.M., O.A.-W.), and the Lymphoma Service (M.L.P., A.Z.), Department of Medicine, and the Department of Pathology (B.H.D.), Memorial Sloan Kettering Cancer Center, the Laboratory of Molecular Electron Microscopy, Rockefeller University (R.Q.N.), and the Department of Pathology and Laura and Isaac Perlmutter Cancer Center, New York University School of Medicine (M.T.W., I.A.) - all in New York; Sylvester Comprehensive Cancer Center at the University of Miami Miller School of Medicine, Miami (S.M., J.A., T.M.T., S.C., A.A., J.T.); the Department of Molecular Physiology and Cell Signaling, Institute of Systems, Molecular, and Integrative Biology, University of Liverpool, Liverpool, United Kingdom (A.J.L.); University of North Carolina Medical Center, Chapel Hill (C.C.C.); and Loxo Oncology at Lilly, Boulder, CO (M.R., D.E.T., K.E., B.B., D.M.H.).
N Engl J Med. 2022 Feb 24;386(8):735-743. doi: 10.1056/NEJMoa2114110.
Covalent (irreversible) Bruton's tyrosine kinase (BTK) inhibitors have transformed the treatment of multiple B-cell cancers, especially chronic lymphocytic leukemia (CLL). However, resistance can arise through multiple mechanisms, including acquired mutations in BTK at residue C481, the binding site of covalent BTK inhibitors. Noncovalent (reversible) BTK inhibitors overcome this mechanism and other sources of resistance, but the mechanisms of resistance to these therapies are currently not well understood.
We performed genomic analyses of pretreatment specimens as well as specimens obtained at the time of disease progression from patients with CLL who had been treated with the noncovalent BTK inhibitor pirtobrutinib. Structural modeling, BTK-binding assays, and cell-based assays were conducted to study mutations that confer resistance to noncovalent BTK inhibitors.
Among 55 treated patients, we identified 9 patients with relapsed or refractory CLL and acquired mechanisms of genetic resistance to pirtobrutinib. We found mutations (V416L, A428D, M437R, T474I, and L528W) that were clustered in the kinase domain of BTK and that conferred resistance to both noncovalent BTK inhibitors and certain covalent BTK inhibitors. Mutations in BTK or phospholipase C gamma 2 (PLCγ2), a signaling molecule and downstream substrate of BTK, were found in all 9 patients. Transcriptional activation reflecting B-cell-receptor signaling persisted despite continued therapy with noncovalent BTK inhibitors.
Resistance to noncovalent BTK inhibitors arose through on-target BTK mutations and downstream PLCγ2 mutations that allowed escape from BTK inhibition. A proportion of these mutations also conferred resistance across clinically approved covalent BTK inhibitors. These data suggested new mechanisms of genomic escape from established covalent and novel noncovalent BTK inhibitors. (Funded by the American Society of Hematology and others.).
共价（不可逆）布鲁顿酪氨酸激酶（BTK）抑制剂改变了多种 B 细胞癌症的治疗方法，尤其是慢性淋巴细胞白血病（CLL）。然而，耐药性可能通过多种机制产生，包括 BTK 残基 C481 上的获得性突变，该残基是共价 BTK 抑制剂的结合位点。非共价（可逆）BTK 抑制剂克服了这种机制和其他耐药机制，但目前对这些治疗方法的耐药机制还不是很了解。
我们对接受非共价 BTK 抑制剂 pirtobrutinib 治疗的 CLL 患者的预处理标本和疾病进展时获得的标本进行了基因组分析。进行结构建模、BTK 结合测定和基于细胞的测定，以研究赋予非共价 BTK 抑制剂耐药性的突变。
在 55 名接受治疗的患者中，我们发现 9 名复发或难治性 CLL 患者存在对 pirtobrutinib 的遗传耐药机制。我们发现突变（V416L、A428D、M437R、T474I 和 L528W）聚集在 BTK 的激酶结构域中，使它们对非共价 BTK 抑制剂和某些共价 BTK 抑制剂都具有耐药性。在所有 9 名患者中均发现了 BTK 或磷脂酶 Cγ2（PLCγ2）的突变，PLCγ2 是 BTK 的信号分子和下游底物。尽管继续使用非共价 BTK 抑制剂治疗，但反映 B 细胞受体信号的转录激活仍然存在。
非共价 BTK 抑制剂的耐药性是由于靶标 BTK 突变和下游 PLCγ2 突变引起的，这些突变使 BTK 抑制逃逸。这些突变中的一部分也使临床上批准的共价和新型非共价 BTK 抑制剂产生耐药性。这些数据提示了从已建立的共价和新型非共价 BTK 抑制剂中基因组逃逸的新机制。（由美国血液学会等资助）。
