title: Lack of effect of 2-chlorodeoxyadenosine therapy in patients with chronic lymphocytic leukemia refractory to fludarabine therapy.
abstract: BACKGROUND
  Fludarabine and 2-chlorodeoxyadenosine are nucleoside analogues that have proved effective in patients with chronic lymphocytic leukemia (CLL). Although their mechanism of action is thought to be similar, a small number of patients who do not respond to fludarabine do respond to 2-chlorodeoxyadenosine. The extent to which 2-chlorodeoxyadenosine is effective in patients who do not respond to fludarabine is not known, however.
  
  
  METHODS
  We treated 28 patients with CLL refractory to fludarabine therapy with a continuous infusion of 2-chlorodeoxyadenosine at a daily dose of 4 mg per square meter of body-surface area for seven days. The treatment could be repeated monthly. The number of treatments ranged from one to five; patients who responded continued to receive treatment until the maximal response was achieved.
  
  
  RESULTS
  Two patients (7 percent) had partial remissions, but no patients had complete remissions. One other patient had a substantial response but had residual thrombocytopenia. The rate of response in most affected organs was 20 percent, but anemia or thrombocytopenia rarely improved. Myelosuppression was frequent, and 65 percent of the courses of 2-chlorodeoxyadenosine therapy were accompanied by febrile episodes or infections. Ten patients died within 60 days of starting therapy with 2-chlorodeoxyadenosine; eight deaths were related to infection. The median platelet count at the start of 2-chlorodeoxyadenosine therapy in these 10 patients was 24,000 per cubic millimeter, as compared with 109,000 per cubic millimeter in the other 18 patients. Five patients were alive after a median follow-up of 24 months.
  
  
  CONCLUSIONS
  Patients with advanced CLL refractory to fludarabine therapy are unlikely to benefit from treatment with 2-chlorodeoxyadenosine. Although 20 percent of the patients have some response, thrombocytopenia and anemia are rarely corrected and may be made worse by 2-chlorodeoxyadenosine therapy.
authors.affiliation: Department of Hematology, University of Texas M.D. Anderson Cancer Center, Houston 77030.
authors.forename: S
authors.initials: S
authors.lastname: O'Brien
authors.forename: H
authors.initials: H
authors.lastname: Kantarjian
authors.forename: E
authors.initials: E
authors.lastname: Estey
authors.forename: C
authors.initials: C
authors.lastname: Koller
authors.forename: B
authors.initials: B
authors.lastname: Robertson
authors.forename: M
authors.initials: M
authors.lastname: Beran
authors.forename: M
authors.initials: M
authors.lastname: Andreeff
authors.forename: S
authors.initials: S
authors.lastname: Pierce
authors.forename: M
authors.initials: M
authors.lastname: Keating
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D017338:Cladribine / Q000009:adverse effects / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D009503:Neutropenia / Q000139:chemically induced; D012074:Remission Induction; D013921:Thrombocytopenia / Q000139:chemically induced; D014740:Vidarabine / Q000031:analogs & derivatives* / Q000627:therapeutic use
chemical_list: D017338:Cladribine; D014740:Vidarabine; C024352:fludarabine