2-CHLORODEOXYADENOSINE (CLADRIBINE)-RELATED EOSINOPHILIA IN PATIENTS WITH LYMPHOPROLIFERATIVE DISEASES

Eosinophilia and allergic skin reactions are uncommon events after 2-c hlorodoxyadenosine (2-CdA, cladribine) administration. A multicentre r etrospective analysis of eosinophilia in 360 patients treated with 2-C dA for lymphoid malignancies has been made, B-cell chronic lymphocytic leukaemia (B-CLL) was diagnosed in 153, hairy cell leukaemia (HCL) in 68, low-grade non-Hodgkin's lymphoma (LGNHL) in 119, high-grade NHL i n 2 and Waldenstrom's macroglobulinaemia (WM) in 18 patients. 2-CdA wa s administered al a dose 0.12 mg/kg/d in 2-h intravenous infusion for 5 consecutive d. The courses were repeated monthly Patients with HCL r eceived 1 cycle of 2-CdA, with NHL 2-6 (mean 3.5) cycles and with B-CL L 3-6 (mean 5) cycles. Twenty patients (5.5%), including 5 with HCL, 6 with LGNHL, 7 with B-CLL and 2 with WM, developed peripheral blood eo sinophilia. The mean values of absolute eosinophil count were 0.78x10( 9)/l (0.58-1.06x10(9)/l), 0.71x10(9)/l (0.52-1.3x10(9)/l), 85 (0.56-1. 82x10(9)/l) and 0.75 (0.74-0.76x10(9)/l), respectively. Eosinophilia o ccurred in 13 patients after 1 course, in 4 after 2 courses, and in 5 after greater than or equal to 3 courses of the therapy. In 17 cases i t resolved spontaneously, Allergic skin lesions with pruritus were not iced in 3 patients simultaneously with an increase in eosinophil count . All of them required antihistaminic drugs and/or corticosteroids, On e patient with B-CLL experienced repeated episodes of eosinophilia. Th e highest incidence of 2-CdA-induced eosinophilia was noticed in patie nts with MW (11.1%) and HCL (7.4%) who received only 1 cycle of this d rug and entered a complete remission. This side effect was less freque ntly observed in LGNHL and B-CLL, i.e, in 5.0% and 4.6% of cases, resp ectively. The mechanism of 2-CdA-induced eosinophilia is not clear. It has been postulated that massive tumour cell lysis may trigger a rele ase of IL-5 and probably other cytokines. The allergic mechanism of 2- CdA-induced eosinophilia is also possible, especially in patients with simultaneous skin reactions.