Interferon alpha in the treatment of hairy cell leukemia

Fifty-four patients with hairy cell leukemia were treated for 7 months with three types of subcutaneously injected interferon: recombinant interferon alfa-2a from Hoffmann-La Roche (3 × 106U daily); recombinant interferon alfa-2b from Schering (2 × 106 U/m2three times per week); and partially purified human leukocyte interferon alpha from the Finnish Red Cross (3 × 106 U daily). After 4 monthsin 27 patients hairy cells decreased dramatically (P < 0.01) while platelets (P < 0.05)monocytes (P < 0.01)polymorphonuclear leukocytes (P < 0.01) and hemoglobin (P < 0.01) increased (in this order) as treatment progressed. Morphometric parameters were used to estimate the relative volume of hairy and myeloid cells present in bone marrow. Biopsies were performed at the beginning of the study and in the secondfourthand seventh months thereafter. Bone marrow disorders were slower to improve as compared with blood. Six severe cases of hairy cell leukemia were responsive to treatmentbut required special monitoring during the first 2 months. All three interferons studied are efficient. Interferon receptorsoncogene (mRNA levels) expressionand the relationship between PDGF and fibrosis in hairy cell leukemia are under investigation.