| Title | Phase II Trial of Recombinant Immunotoxin RFB4(dsFv)-PE38 (BL22) in Patients With Hairy Cell Leukemia. | | Author(s) | Kreitman RJ, Stetler-Stevenson M, Margulies I, Noel P, Fitzgerald DJ, Wilson WH, Pastan I | | Institution | Laboratory of Molecular Biology, Laboratory of Clinical Pathology, and Medicine Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD. | | Source | J Clin Oncol 2009 May 4. | | Abstract | PURPOSE: To conduct a phase II trial in chemoresistant hairy cell leukemia (HCL) with BL22, a recombinant anti-CD22 immunotoxin which showed phase I activity in HCL.
PATIENTS AND METHODS: Eligible patients had relapsed/refractory HCL and needed treatment based on blood counts. Patients were stratified into three groups: response to cladribine less than 1 year, those with a response lasting 1 to 4 years, or no response and uncontrolled infection. Patients received BL22 40 microg/kg every other day for three doses on cycle 1. Those achieving hematologic remission (HR), defined as neutrophils >/= 1,500/mm(3), hemoglobin >/= 11 g/dL, and platelets >/= 100,000/mm(3), were observed. Patients without HR were re-treated at 30 microg/kg every other day for three doses every 4 weeks beginning at least 8 weeks after cycle 1.
RESULTS: Thirty-six patients were enrolled including 26, nine, and one in groups 1 to 3. The response after one cycle (CR, 25%; PR, 25%) improved when 56% were re-treated (CR, 47%; PR, 25%). CR rate was similar in groups 1 and 2 (P = .7). Twenty-two with baseline spleen height lower than 200 mm had higher CR (64% v 21%; P = .019) and OR rates (95% v 36%; P = .0002) compared to 14 with spleens either absent or higher than 200 mm. The only serious toxicity was reversible grade 3 hemolytic uremic syndrome, not requiring plasmapheresis, in two patients (6%). High neutralizing antibodies were observed in four patients (11%) and prevented re-treatment.
CONCLUSION: BL22 activity in HCL is confirmed. Best responses to BL22 after cladribine failure are achieved before the patients develop massive splenomegaly or undergo splenectomy. | | Language | ENG | | Pub Type(s) | JOURNAL ARTICLE
| | PubMed ID | 19414673 |
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