Analysis of anaplastic lymphoma kinase status in rhabdomyosarcomas: correlation with clinicopathological findings

Introduction. Rhabdomyosarcoma (RMS) is a highly malignant tumor occurring mostly in children. Multimodal therapy is currently promising, however, in patients with high risk (per the stratification scale) low survival rates are observed. There remains a necessity for new possibilities in treatment of this category of patients. Currently, anaplastic lymphoma kinase (ALK) is of considerable interest.Aim. To study expression of ALK as a potential target marker in RMS tissues.Materials and methods. In total, 202 histological RMS blocks were studied. ALK expression was qualitatively measured using immunohistochemistry, and its correlation with histological tumors subtype and patient’s clinical data was evaluated.Results. ALK expression in samples of alveolar RMS was observed in 68 % (41/60) of cases, samples of embryonal RMS in 30 % (26/87) cases, samples of spindle cell/sclerosing RMS in 7 % (1/14) of cases, samples of epithelioid RMS (EpiRMS) in 100 % (2/2) of cases. The study showed correlation between ALK expression and alveolar RMS subtype (р <0.05). In all cases of alveolar RMS with focal ALK D5F3 expression, primarily low or moderate activity levels against anti-myogenin and MyoD1 were observed. ALK-positive samples in the embryonal and spindle cell/sclerosing RMS samples were rarer.Conclusion. The results show that ALK is a promising target for treatment of patients with RMS. Further study of additional genetic aberrations of ALK is planned which could serve as a springboard for development of targeted therapy.