PHASE-II MULTICENTER STUDY OF HUMAN CD52 ANTIBODY IN PREVIOUSLY TREATED CHRONIC LYMPHOCYTIC-LEUKEMIA

Purpose: CAMPATH-1H is a human immunoglobulin G(1) (IgG(1)) anti-CD52 monoclonal antibody (MAb) that binds to nearly all B- and T-cell lymph omas and leukemias. We report the results of a multicenter phase II tr ial that used CAMPATH-1H in previously chemotherapy-treated patients w ith chronic lymphocytic leukemia (CLL). Materials and Methods: Twenty- nine patients who had relapsed after an initial response (n = 8) or we re refractory (n = 21) to chemotherapy were treated with CAMPATH-1H ad ministered as a 30-mg 2-hour intravenous (IV) infusion thrice weekly f or a maximum period of 12 weeks. Results: Eleven patients (38%) achiev ed a partial remission (PR) and one (4%) a complete remission (CR) (re sponse rate, 42%; 95% confidence interval [CI], 23% to 61%). Three of eight patients (38%) with a relapse and nine of 21 refractory patients (43%) responded to CAMPATH-1H therapy, CLL cells were rapidly elimina ted from blood in 28 of 29 patients (97%), CR in the bone marrow was o btained in 36% and splenomegaly resolved completely in 32%. Lymphadeno pathy was normalized in only two patients (7%). The median response du ration was 12 months (range, 6 to 25+). World Health Organization (WHO ) grade IV neutropenia and thrombocytopenia developed in three (10%) a nd two patients (7%), respectively. Neutropenia and thrombocytopenia r ecovered in most responding patients during continued CAMPATH-1H treat ment. Lymphopenia (< 0.5 x 10(9)/L) occurred in all patients, Two pati ents had opportunistic infections and four had bacterial septicemia. C onclusion: CAMPATH-1H had significant activity in patients with advanc ed and chemotherapy-resistant CLL, The most pronounced effects were no ted in blood, bone marrow, and spleen, preferential clearance of blood may allow harvesting of uncontaminated blood stem cells for use in hi gh-dose chemotherapy protocols. (C) 1997 by American Society of Clinic al Oncology.