Purpose: Older acute myeloid leukemia (AML) patients have a poor prognosis; therefore, novel therapies are needed. Allogeneic natural killer (NK) cells have been adoptively transferred with promising clinical results. Here, we report the first-inhuman study exploiting a unique scalable NK-cell product generated ex vivo from CD34+ hematopoietic stem and progenitor cells (HSPC) from partially HLA-matched umbilical cord blood units. Experimental Design: Ten older AML patients in morphologic complete remission received an escalating HSPC-NK cell dose (between 3 and 30 × 106/kg body weight) after lymphodepleting chemotherapy without cytokine boosting. Results: HSPC-NK cell products contained a median of 75% highly activated NK cells, with <1 × 104 T cells/kg and <3 × 105 B cells/kg body weight. HSPC-NK cells were well tolerated, and neither graft-versus-host disease nor toxicity was observed. Despite no cytokine boosting being given, transient HSPC-NK cell persistence was clearly found in peripheral blood up to 21% until day 8, which was accompanied by augmented IL15 plasma levels. Moreover, donor chimerism up to 3.5% was found in bone marrow. Interestingly, in vivo HSPC-NK cell maturation was observed, indicated by the rapid acquisition of CD16 and KIR expression, while expression of most activating receptors was sustained. Notably, 2 of 4 patients with minimal residual disease (MRD) in bone marrow before infusion became MRD negative (<0.1%), which lasted for 6 months. Conclusions: These findings indicate that HSPC-NK cell adoptive transfer is a promising, potential "off-the-shelf" translational immunotherapy approach in AML.

doi.org/10.1158/1078-0432.CCR-16-2981, hdl.handle.net/1765/108175
Clinical Cancer Research

Dolstra, H., Roeven, M.W.H. (Mieke W.H.), Spanholtz, J., Hangalapura, B.N. (Basav N.), Tordoir, M. (Marleen), Maas, F. (Frans), … Schaap, N. (2017). Successful transfer of umbilical cord blood CD34+ hematopoietic stem and progenitor-derived NK cells in older acute myeloid leukemia patients. Clinical Cancer Research, 23(15), 4107–4118. doi:10.1158/1078-0432.CCR-16-2981