Cytokine-induced memory-like NK cells combined with Tafasitamab demonstrate efficacy against B-cell acute lymphoblastic leukemia

Cytokine-induced memory-like natural killer cells (CIMLNK) represent a novel form of adoptive cellular therapy that is easy to manufacture and readily available. These cells are generated after overnight stimulation of purified natural killer (NK) cells with interleukin-12 (IL-12), interleukin-15 (IL-15), and interleukin-18 (IL-18). While CIMLNK has demonstrated efficacy in patients with relapsed or refractory acute myeloid leukemia (AML), its potential application in B-cell acute lymphoblastic leukemia (B-ALL) remains unclear. Tafasitamab (TAFA), a monoclonal antibody (mAb) directed against CD19, a surface antigen expressed on B-ALL cells, has been developed to augment anti-tumor efficacy through antibody-dependent cellular cytotoxicity (ADCC), a mechanism predominantly mediated by NK cells. Consequently, we sought to assess the susceptibility of B-ALL to the combination of CIMLNK and TAFA using three B-ALL cell lines: NALM6, SUP-B15, and RS4;11. The addition of TAFA significantly augmented the cytotoxic activity, degranulation capacity, and IFN-γproduction of CIMLNK. TAFA-induced ADCC was found to be dose-dependent and was abolished after CD16 blockade. Furthermore, TAFA-mediated effects against NALM6 and SUP-B15 were more pronounced in CIMLNK compared to unstimulated NK cells. In vivo, the combination of CIMLNK and TAFA led to a more pronounced survival benefit in leukemia-bearing mice. In summary, our findings suggest that this combination holds promise as a potential alternative treatment option for patients with relapsed refractory B-ALL.