The diagnostic potential of nanobodies in acute myeloid leukemia.

Acute myeloid leukemia (AML) is a heterogeneous hematologic cancer, which is caused by clonal expansion of immature myeloid precursors, leading to bone marrow failure and poor long-term survival, especially in older patients and those with adverse-risk features. Relapse, primarily from chemotherapy-resistant leukemic stem cells (LSCs) in protective niches, remains the leading cause of mortality despite genomic advancements and targeted therapies like FLT3 inhibitors and all-trans retinoic acid for acute promyelocytic leukemia. Conventional antibody-based approaches, such as gemtuzumab ozogamicin, offer benefits but are limited by poor tissue penetration, Fc-mediated off-target effects, toxicity, and high costs, particularly with antigens shared by normal progenitors. Single-domain antibodies (nanobodies), compact (~ 12–15 kDa) scaffolds from camelid heavy-chain antibodies, address these challenges through superior stability, solubility, tissue infiltration, and modular engineering for multivalent/multispecific formats. This review explores AML’s molecular pathogenesis, emphasizing recurrent abnormalities (e.g., NPM1, FLT3, CEBPA mutations) that guide risk stratification and interventions. Diagnostic modalities morphology, flow cytometry, cytogenetics, and next-generation sequencing (NGS) are evaluated for subtype identification and measurable residual disease (MRD) monitoring. Nanobodies excel in positron emission tomography/single photon emission computed tomography (PET/SPECT) imaging of markers like CD33 and AXL, yielding high tumor-to-background ratios in preclinical models, alongside fluorescent conjugates and chromobodies for live-cell visualization. Therapeutic bispecific engagers and CAR-T constructs targeting CD33/CD123 show potent activity against heterogeneous blasts and LSCs. Challenges include antigen variability, rapid clearance, and bone marrow access, mitigated by optimizations like PEGylation. Nanobodies promise precision AML management, enhancing detection, specificity, and relapse prevention through clinical translation.