Prognostic Significance of Peanut Agglutinin Binding in Childhood T-Cell Acute Lymphoblastic Leukemia

We previously reported the favorable prognosis associated with positive peanut agglutinin (PNA) binding in childhood T-cell acute lymphoblastic leukemia (ALL), and hypothesized that this may be related to glucocorticoid sensitivity. The purposes of this prospective study involving 43 children with newly diagnosed T-cell ALL were to determine the relation between PNA binding and in vitro resistance to prednisolone (PRD) and dexamethasone (DXM), in vivo response to a systemic PRD monotherapy (plus one intrathecal injection with methotrexate) and to multidrug chemotherapy. PNA positivity was found in 28 (65%) out of the 43 cases. PNA-negative samples in vitro were not more resistant to PRD or DXM than PNA-positive samples. However, in 38 evaluable T-cell ALL patients, nine out of 13 PNA-negative cases were poor responders to PRD in vivo, while all 25 PNA-positive cases were good responders to PRD in vivo (p < 0.0001). PNA-positive patients had a 3.4-fold (95% confidence interval, CI, 1.1-10.4, p = 0.03) lower relative risk of any event than PNA-negative patients. The 3-year probability of event-free survival was 0.81 for PNA-positive patients and 0.40 for PNA-negative patients. In conclusion, PNA positivity is a marker for a subgroup of T-cell ALL patients who are very likely to respond well to systemic PRD monotherapy. In addition, PNA positivity is a favorable prognostic factor regarding event-free survival in childhood T-cell ALL.