Ho: Ibalizumab Development Progress Report Abstracts continued
To assess the potency and breadth of ibalizumab, we tested its ability to neutralize infection by a diverse panel of HIV-1 isolates in collaboration with Dr. Michael Seaman at the Beth Israel Deaconess Medical Center, part of the Montefiore Antibody Vaccine Immune Monitoring Consortium (Ab VIMC). Of the one hundred-sixteen Env-pseudotyped viruses tested, ibalizumab demonstrated potent neutralization against almost all viruses at nanomolar concentrations and exhibited extremely broad neutralization irrespective of envelope diversity.
In collaboration with TaiMed Biologics, we are pursuing clinical development of subcutaneous (SC) formulation of ibalizumab. We conducted a pharmacokinetic study in rhesus macaques to measure the half-life and activity of the SC formulation in collaboration with the Tulane National Primate Research Center and the Montefiore Ab VIMC. Pharmacokinetic modeling based on serum ibalizumab levels revealed that the SC formulation doubled the half-life relative to the intravenous formulation. The serum from macaques receiving SC ibalizumab was able to neutralize SIV in vitro, establishing that ibalizumab remained active after SC injection. We are moving forward with the clinical development of the SC ibalizumab formulation and received permission from the US FDA to proceed with a Phase 1 clinical trial of SC ibalizumab in HIV-uninfected volunteers, anticipated to begin by the end of 2010.
In collaboration with researchers at the Children’s Hospital of Philadelphia, we are exploring an antibody gene-transfer approach to express ibalizumab using a recombinant adeno-associated virus vector (rAAV). We have generated several ibalizumab immunoadhesin proteins, and all of them demonstrated a functional activity similar to full‐length ibalizumab in vitro. We are now poised to proceed with an in vivo expression and functional characterization study using rAAV vectors in mice and nonhuman primates.