Treatment with low doses of RG7112 and Peg-IFNα 2a decreases the ability of MPN CD34⁺ cells to repopulate the BM and spleen of NSG mice. (A) Prior treatment of MF spleen CD34⁺ cells with low doses of RG7112 and Peg-IFNα 2a reduced the spleen size and weight in a recipient NSG mouse. The transplantation of untreated PMF CD34⁺ led to an enlarged spleen 7 months after transplantation, whereas recipient mice transplanted with CD34⁺ treated with either RG7112 or Peg-IFNα 2a alone or in combination had smaller spleens. Similar results were observed when CD34⁺ cells from this same patient were transplanted into a second set of NSG mice. (B) Treatment with RG7112 and Peg-IFNα 2a alone or in combination decreased both donor-derived myeloid and lymphoid cells (CD19, CD33, CD41a, and CD235) in the BM of recipient NSG mice.