RT Journal Article SR Electronic T1 CD4 coating, but not CD4 depletion, is a predictor of efficacy with primatized monoclonal anti-CD4 treatment of active rheumatoid arthritis. JF The Journal of Rheumatology JO J Rheumatol FD The Journal of Rheumatology SP 220 OP 229 VO 29 IS 2 A1 Ursula Mason A1 Jose Aldrich A1 Ferdinand Breedveld A1 Charles B Davis A1 Michael Elliott A1 Mildred Jackson A1 Christian Jorgensen A1 Edward Keystone A1 Robert Levy A1 John Tesser A1 Mark Totoritis A1 Alemseged Truneh A1 Michael Weisman A1 Craig Wiesenhutter A1 David Yocum A1 Jin Zhu YR 2002 UL http://www.jrheum.org/content/29/2/220.abstract AB OBJECTIVE: Double blind studies were conducted with the anti-CD4 monoclonal antibody (Mab) keliximab in patients with active, stable rheumatoid arthritis (RA), to confirm preliminary evidence of efficacy and safety from open. uncontrolled studies. METHODS: We enrolled 136 and 186 patients into 2 consecutive, randomized, double blind trials, with similar populations [apart from inclusion of disease modifying antirheumatic drug (DMARD)-naïve patients in Study 2]. Patients received 4 weeks intravenous placebo or keliximab [40, 80, 120, or 140 mg twice weekly (bw), or 240 mg once weekly (ow)].The primary endpoint was the American College of Rheumatology (ACR) 20 response criteria, one week after the end of treatment. RESULTS: ACR 20 response rates in Study I were 19%, 42%, 51%*, and 69%* (*p < 0.05 compared to placebo), with placebo, 40, 80, or 140 mg keliximab bw, respectively. The response rates in Study 2 were 30%, 39%, 46% and 47% with placebo, 80 or 120 mg bw, or 240 mg keliximab ow, respectively. In the 2 studies, there was a dose dependent increase in peripheral blood CD4+ T cell coating with keliximab, but a different pattern of CD4 depletion was seen. While only 12% of keliximab treated patients in Study I had CD4 counts below 250 cells/mm3 at the end of the treatment period, 47% fell below this level in Study 2. Clinical response was not correlated with CD4 depletion, but was correlated with CD4+ T cell coating with keliximab. CONCLUSION: Coating of peripheral blood CD4+ T cells with keliximab, but not CD4 depletion, is a determinant of clinical response.