Revealing the molecular mechanism of central nervous system leukemia with single-cell technology

Isolated Central Nervous System Infiltrated and Progressed to Acute Myeloid Leukemia from Chronic Myeloid Leukemia with e1a3 BCR-ABL1 Transcript: A Rare Case Report and Literature Review

The chronic myeloid leukemia (CML) is easily diagnosed by laboratory examination, however, rare BCR-ABL1 mRNA transcripts variants, such as e1a3 present diagnosis and therapeutic challenges. This case report details the diagnosis and management of a CML patient with the e1a3 transcript by FISH and RT-PCR. Following initial diagnosis, the patient was treated with the tyrosine kinase inhibitor (TKI) Flumatinib. During the treatment, although the FCM-MRD of the bone marrow kept negative, the e1a3 expression detected by PCR always remained positive. After eighteen months, the patient experienced headaches, vomiting, and blurred vision. Subsequent bone marrow analysis and flow cytometry detection of cerebrospinal fluid indicated that the patient had entered the blast phase, progressing to acute myeloid leukemia (AML). Treatment was switched to the third-generation TKI olverembatinib, combined with chemotherapy, followed by allogeneic hematopoietic stem cell transplantation. The patient remains disease-free following olverembatinib maintenance therapy. This case underscores the importance of comprehensive diagnostic apporsches and the potential efficacy of third-generation TKIs and allo-HSCT in the treatment of e1a3-type CML.

Integrin α6-Targeted Molecular Imaging of Central Nervous System Leukemia in Mice

Central nervous system leukemia (CNS-L) is caused by leukemic cells infiltrating into the meninges or brain parenchyma and remains the main reason for disease relapse. Currently, it is hard to detect CNS-L accurately by clinically available imaging models due to the relatively low amount of tumor cells, confined blood supply, and the inferior glucose metabolism intensity. Recently, integrin α6-laminin interactions have been identified to mediate CNS-L, which suggests that integrin α6 may be a promising molecular imaging target for the detection of CNS-L. The acute lymphoblastic leukemia (ALL) cell line NALM6 stabled and transfected with luciferase was used to establish the CNS-L mouse model. CNS-L-bearing mice were monitored and confirmed by bioluminescence imaging. Three of our previously developed integrin α6-targeted peptide-based molecular imaging agents, Cy5-S5 for near-infrared fluorescence (NIRF), Gd-S5 for magnetic resonance (MR), and ¹⁸F-S5 for positron emission tomography (PET) imaging, were employed for the molecular imaging of these CNS-L-bearing mice. Bioluminescence imaging showed a local intensive signal in the heads among CNS-L-bearing mice; meanwhile, Cy5-S5/NIRF imaging produced intensive fluorescence intensity in the same head regions. Moreover, Gd-S5/MR imaging generated superior MR signal enhancement at the site of meninges, which were located between the skull bone and brain parenchyma. Comparatively, MR imaging with the clinically available MR enhancer Gd-DTPA did not produce the distinguishable MR signal in the same head regions. Additionally, ¹⁸F-S5/PET imaging also generated focal radio-concentration at the same head regions, which generated nearly 5-times tumor-to-background ratio compared to the clinically available PET radiotracer ¹⁸F-FDG. Finally, pathological examination identified layer-displayed leukemic cells in the superficial part of the brain parenchyma tissue, and immunohistochemical staining confirmed the overexpression of the integrin α6 within the lesion. These findings suggest the potential application of these integrin α6-targeted molecular imaging agents for the accurate detection of CNS-L.