title: The safety profile of low-dose cladribine in refractory rheumatoid arthritis. A pilot trial.
abstract: Cladribine (2-chlorodeoxyadenosine, 2-CdA) is a newer purine analog with specific toxicity to lymphocytes. As lymphocytes play a major role in rheumatoid arthritis (RA), we assessed the safety profile of low-dose 2-CdA in patients who were refractory to more than three disease-modifying drugs. Five patients were given a subcutaneous dosage of 0.05 mg/kg 2-CdA weekly over a period of 8 weeks. Of the lymphocyte subsets, both T and B cells decreased below the normal range, whereas natural killer cells remained stable. These changes were the only side-effects noted during treatment and 4 weeks afterwards. In one patient a pacemaker was implanted for reasons unlikely to be related to 2-CdA administration. We conclude that even low-dose 2-CdA (0.05 mg/kg) can decrease T and B cell populations in patients with refractory RA, but other side-effects are unlikely. For assessing the possible clinical efficacy of low-dose 2-CdA further studies are warranted.
authors.affiliation: Department of Internal Medicine, Leopold-Franzens-University Innsbruck, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Schirmer
authors.forename: E
authors.initials: E
authors.lastname: Mur
authors.forename: K P
authors.initials: KP
authors.lastname: Pfeiffer
authors.forename: J
authors.initials: J
authors.lastname: Thaler
authors.forename: G
authors.initials: G
authors.lastname: Konwalinka
mesh_terms: D000368:Aged; D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000009:adverse effects; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000276:immunology; D016516:CD4-CD8 Ratio; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D017338:Cladribine / Q000008:administration & dosage* / Q000009:adverse effects; D005260:Female; D006801:Humans; D007166:Immunosuppressive Agents / Q000008:administration & dosage* / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D012449:Safety
chemical_list: D000970:Antineoplastic Agents; D007166:Immunosuppressive Agents; D017338:Cladribine