Soluble l‐selectin (sCD62L) in relapsed childhood acute lymphoblastic leukaemia

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Abstract
Summary. Soluble l‐selectin (sCD62L) plasma concentrations at diagnosis and outcome were investigated in 193 children at first relapse of acute lymphoblastic leukaemia (ALL) after treatment according to the Berlin–Frankfurt–Münster relapsed ALL multicentre trials, ALL‐REZ BFM 95 and 96. sCD62L was low (< fifth paediatric reference percentile) in 63 (33%) and high (> 95th percentile) in 36 (19%) children, and was independent of remission duration, sex, BCR–ABL fusion or extramedullary disease. High sCD62L was associated with circulating blasts and T‐cell phenotype. More initial adverse events occurred in children with high and low levels of sCD62L (23 out of 99) than in those with normal levels (9 out of 94, P = 0·018). Among 75 worst‐prognosis patients (risk groups S3/S4, isolated bone marrow relapse occurring less than 6 months after elective cessation of front‐line therapy, or T‐cell phenotype with bone marrow involvement), 27 had low sCD62L and decreased event‐free survival (EFS) probability (PEFS5 = 0·09 at 5 years) and duration (219 d) compared with normal sCD62L (29 out of 75, PEFS5 = 0·24, 640 d, P = 0·01). Low (44 out of 118), normal (72 out of 118), and high (19 out of 118) sCD62L non‐S3/S4 patients fared similarly (average PEFS5 = 0·45, 1369 d; P = 0·5). Low sCD62L may be a marker of malignant blasts replacing normal sCD62L‐producing haematopoietic cells. In children with first relapse of ALL and worst prognosis, plasma sCD62L may be useful for risk‐adapted stratification.