Central nervous system relapse in a pediatric anaplastic large cell lymphoma patient with CLTC/ALK translocation treated with alectinib: A case report.

Background: The aberrant expression of the anaplastic lymphoma kinase () gene in ALK-positive (ALK+) anaplastic large cell lymphoma (ALCL) is usually due to t(2;5)/NPM-ALK. However, rarely, aberrant ALK expression can also result from a rearrangement of the gene with various partner genes. Central nervous system (CNS) metastasis is very rare in ALK+ALCL. Patients with CNS involvement show an inferior prognosis.

Case Summary: Here, we present the case of an 8-year-old girl diagnosed with ALK+ALCL. She presented with fever, skin nodules, leg swelling, and abdominal pain over the preceding 6 mo. She had extensive involvement and showed an extraordinary rare translocation, t(2;17)/CLTC-ALK, as demonstrated by RNA-seq. She underwent chemotherapy as per ALCL99, followed by vinblastine (VBL) maintenance treatment, and achieved complete remission. However, she developed CNS relapse during VBL monotherapy. The patient achieved a durable second remission with high-dose chemotherapy (including methotrexate 8 g/m) and continuous treatment with alectinib and VBL.

Conclusion: Alectinib showed significant and durable CNS effects in this patient. However, more cases are needed to prove the efficacy and safety of alectinib for pediatric ALK+ALCL patients.