Investigating the Mechanistic Basis for Hepatic Toxicity Induced by an Experimental Chemokine Receptor 5 (CCR5) Antagonist Using a Compendium of Gene Expression Profiles

Commercialization challenges associated with induced pluripotent stem cell-based products

Induced pluripotent stem (iPS) cells have generated excitement in the regenerative medicine industry. Products derived from iPS cells could be used in a range of drug discovery and development processes. These nontherapeutic products will continue to be launched over the next 5 years, and provide income and knowledge to drive the therapeutic use of iPS cells forward. While the commercial opportunity for iPS cell-based therapies is potentially large, the looming technical and scientific hurdles must be overcome and, thus, the launch of a therapy based on iPS cells is unlikely to occur until the 2020s. While the launch of a therapeutic is many years away, the business models for commercialization should be well understood and proven based on experience with other non-iPS cell-based therapies (both autologous and allogeneic) that will already be on the market.

Reduction of CCR5 with low-dose rapamycin enhances the antiviral activity of vicriviroc against both sensitive and drug-resistant HIV-1

Vicriviroc (VCV) is a chemokine (C-C motif) receptor 5 (CCR5) antagonist with potent anti-HIV activity that currently is being evaluated in phase III clinical trials. In the present study, donor CCR5 density (CCR5 receptors/CD4 lymphocytes) inversely correlated with VCV antiviral activity (Spearman's correlation test; r = 0.746, P = 0.0034). Low doses of the transplant drug rapamycin (RAPA) reduced CCR5 density and enhanced VCV antiviral activity. In drug interaction studies, the RAPA/VCV combination had considerable antiviral synergy (combination indexes of 0.1-0.04) in both multicycle and single-cycle infection of lymphocytes. The synergy between RAPA and VCV translated into dose reduction indexes of 8- to 41-fold reductions for RAPA and 19- to 658-fold reductions for VCV. RAPA enhanced VCV antiviral activity against both B and non-B clade isolates, potently suppressing clade G viruses with reported reduced sensitivities to VCV and to the licensed CCR5 antagonist maraviroc. Importantly, RAPA reduction of CCR5 density in lymphocytes sensitized VCV-resistant strains to VCV, inhibiting virus production by approximately 90%. We further demonstrated the role of CCR5 density on VCV activity against resistant virus in donor lymphocytes and in cell lines expressing varying CCR5 densities. Together, these results suggest that low doses of RAPA may increase the durability of VCV-containing regimens in patients by enhancing VCV viral suppression, by allowing the use of lower doses of VCV with reduced potential for toxicity, and by controlling emerging VCV-resistant variants.