Antiretroviral Activity of the Anti-CD4 Monoclonal Antibody TNX-355 in Patients Infected with HIV Type 1

Background. We wished to determine the safety and anti-human immunodeficiency virus (HIV) type 1 activity of single doses of TNX-355, a humanized IgG4 anti-CD4 monoclonal antibody with potent activity against HIV-1 in vitro, in HIV-infected subjects. Methods. Sequential cohorts of 6 HIV-1-infected subjects each received infusions of TNX-355. Data included plasma HIV-1 RNA level, CD4⁺ T cell count, TNX-355 coating of CD4⁺ T cells, and serum TNX-355 levels. Results. Dose-related reductions in plasma HIV-1 RNA loads correlated with complete CD4⁺ T cell coating by TNX-355. Peak median decreases in plasma HIV-1 RNA loads were 0.56, 1.33, and 1.11 log₁₀ copies/mL and occurred on days 4-7, 14, and 21 for the 3.0, 10, and 25 mg/kg doses, respectively. Dose-dependent increases in CD4⁺ T cell count occurred within 24 h of dosing. Conclusions. Single doses of TNX-355 reduced plasma HIV-1 RNA loads and increased CD4⁺ T cell counts in HIV-infected subjects. The further assessment of therapeutic potential awaits data from longer-duration trials.