Presentation Abstract

Session: 099-Antiretroviral Therapy of HIV-1 Infection
Sunday, Sep 18, 2011, 11:15 AM - 1:15 PM
Presentation Title: H2-794b - Safety, Efficacy, and Pharmacokinetics of Ibalizumab in Treatment-Experienced HIV-1 Infected Patients: a Phase 2b Study
Location: Exhibit Hall F1
Poster Board Number: 283
Presentation Number: H2-794b
Pres. Time: Sunday, Sep 18, 2011, 11:15 AM - 1:15 PM
Category: H2
Keywords: ibalizumab; antiretroviral; monoclonal antibody
Author(s): H. Khanlou, MD - Chief of Medicine 1, J. GatheJR., MD - President 2, S. Schrader, MD - Director 3, W. Towner, MD - Medical Director 4, S. Weinheimer, PhD - Sr. Director 5, S. Lewis, MD - Chief Medical Officer5;
1AIDS Hlth. Care Fndn., Los Angeles, CA, 2Therapeutic Concepts, Houston, TX, 3Res. Access Network, Houston, TX, 4Kaiser Permanente, Los Angeles, CA, 5TaiMed Biologics USA, Irvine, CA.
Financial Disclosures:  H. Khanlou, None..
J. Gathe, None..
S. Schrader, None..
W. Towner, None. 
S. Weinheimer,
TaiMed Biologics USA Role(s): Employee, Received: Salary.
S. Lewis,
TaiMed Biologics USA Role(s): Employee, Shareholder (excluding diversitied mutual funds), Received: Salary.
Abstract: Background: Ibalizumab is a novel humanized monoclonal antibody that binds to a conformational epitope on domain 2 of the CD4 receptor, blocking entry of HIV-1 into target cells. A prior Phase 2a trial demonstrated statistically significant viral load reduction when ibalizumab was combined with optimized background regimen (OBR) versus placebo plus OBR. A 24-week (wk) randomized, double-blind, Phase 2b study was conducted to optimize dosing regimens. Methods: 113 treatment-experienced HIV-1 infected patients (89% male; 62% white; mean age 48 years) with documented resistance to at least one NRTI, one NNRTI and one PI were randomized to ibalizumab 800mg IV q2wks or 2000mg IV q4wks. All patients were also treated with OBR that contained at least one sensitive agent per screening resistance testing. Virologic failure was defined as HIV-RNA (VL) decline less than 1 log10 from baseline (BL) at WK 16 or failure to achieve <50 copies/mL at WK 24. The primary endpoint was the percent of patients with VL <50 copies/mL at WK 24. Results: Ibalizumab was well tolerated with no drug-related deaths, serious adverse events, or discontinuations, and no clinically relevant effects on vital signs or laboratories. The most common treatment-emergent adverse events (AEs) were rash, diarrhea, headache, and nausea with no significant difference between arms. Most AEs were mild to moderate in intensity. Conclusions: Treatment with ibalizumab 800mg q2wks + OBR and 2000mg q4wks + OBR was well tolerated and resulted in significant viral load reductions over 24 weeks. These data support continued development of ibalizumab as a new agent for treating HIV in treatment-experienced patients.
Summary of Efficacy Data at WK 24
Criteria800 mg q2wk + OBR
N = 59
2000 mg q4wk + OBR
N = 54
Mean (SD) VL change log10*-1.6 (1.3)-1.5 (1.4)
N (%) >1.0 log10 reduction37 (63)32 (59)
N (%) <400 copies/mL34 (58)25 (46)
N (%) <200 copies/mL31 (53)23 (43)
N (%) <50 copies/mL26 (44)15 (28)
Mean (SD) increase in CD4+ (cells/uL)37 (63)40 (80)
*Intent-to-Treat; Missing Equals Failure, missing value imputed to no change from BL

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