The objective of the study is to evaluate the safety and feasibility of giving autologous SB-728mR-HSPC to HIV-1 (R5) infected patients who are being treated with cART and have undetectable virus but suboptimal CD4+ cell levels. To strengthen the possibility that CCR5-disrupted HSPCs engraft, patients will receive either a two- or three-day (Cohort 1 or Cohort 2) course of busulfan (dose targeting AUC of 4000 µM/day) before being infused with the genetically modified cells. At 9-12 months after SB-728mR-HSPC infusion, subjects who are aviremic with CD4 cell counts ≥600 cells/µL and have ≥1% CCR5-modified CD4 cells within the peripheral blood detected by pentamer PCR will undergo an ATI.
The purpose of the study is to evaluate the safety and feasibility of administering SB-728mR-HSPC after conditioning with busulfan.