Nektar Therapeutics announced the publication of preclinical data in Blood Advances, the open-access journal of the American Society of Hematology, highlighting the effects of NKTR-255, a novel polymer-conjugated human IL-15, on the efficacy of human CD19 CAR-T cells in a xenogeneic lymphoma model and on CD8+ T effector cell (Tcell) and natural killer (NK) cell proliferation in non-human primates. The data from this publication demonstrate that NKTR-255 not only enhanced in vivo proliferation and accumulation of T and NK cells in non-human primates, but also demonstrated enhanced in vivo antitumor efficacy of human CD19 CAR-T in lymphoma-bearing immunodeficient mice. Key findings are summarized below: Serum IL-15 concentration is independently associated with longer CD19 CAR-T persistence in humans, NKTR-255 promotes CD8+ effector and memory T and NK cell accumulation in non-human primates, NKTR-255 enhances proliferation and survival of human CD19 CAR-T at low target cell abundance and NKTR-255 enhances accumulation and efficacy of human CD19 CAR-T in lymphoma bearing immunodeficient mice.