Acquired resistance to crizotinib in novel CDK14-ALK and CLTC-ALK fusions of ALK-positive large B-cell lymphoma identified by next-generation sequencing

Anaplastic lymphoma kinase-positive large B-cell lymphoma (ALK(+) LBCL) is a rare subtype of non-Hodgkin lymphoma. ALK inhibitors are being tried to treat recurrent/refractory ALK(+) LBCL. A majority of patients with ALK(+) tumors respond to crizotinib, but partial cases ultimately develop resistance about a year later. Here, we report a case of ALK(+) LBCL carrying a new fusion gene involving CDK14 and ALK, CLTC-ALK gene rearrangements and MTOR gene mutation. The patient had progressive disease after combination of crizotinib and chemotherapy treatment about 5.5 months later, accompanied by reduced abundance of CDK14-ALK, increased abundance of CLTC-ALK and a novel MFHAS1 gene mutation. However, MTOR mutation turned negative. The patient received alectinib combined with hyper-CVAD, then followed by alectinib as monotherapy for 21 months. The patient achieved partial response and remained in a stable condition. This case suggests that CDK14-ALK fusion gene may be more sensitive to crizotinib than CLTC-ALK fusion gene. MTOR is associated with the anti-tumor mechanism of ALK inhibitors. MFHAS1 gene mutation and/or CLTC-ALK gene copy number amplification may involve resistance to crizotinib. Furthermore, alectinib may inhibit the carcinogenicity of these gene changes and improve the prognosis of ALK(+) LBCL.