Off-the-shelf CAR natural killer cells secreting IL-15 target spike in treating COVID-19.

Engineered natural killer (NK) cells represent a promising option for immune therapy option due to their immediate availability in allogeneic settings. Severe acute diseases, such as COVID-19, require targeted and immediate intervention. Here we show engineering of NK cells to express (1) soluble interleukin-15 (sIL15) for enhancing their survival and (2) a chimeric antigen receptor (CAR) consisting of an extracellular domain of ACE2, targeting the spike protein of SARS-CoV-2. These CAR NK cells (mACE2-CAR_sIL15 NK cells) bind to VSV-SARS-CoV-2 chimeric viral particles as well as the recombinant SARS-CoV-2 spike protein subunit S1 leading to enhanced NK cell production of TNF-α and IFN-γ and increased in vitro and in vivo cytotoxicity against cells expressing the spike protein. Administration of mACE2-CAR_sIL15 NK cells maintains body weight, reduces viral load, and prolongs survival of transgenic mice expressing human ACE2 upon infection with live SARS-CoV-2. These experiments, and the capacity of mACE2-CAR_sIL15 NK cells to retain their activity following cryopreservation, demonstrate their potential as an allogeneic off-the-shelf therapy for COVID-19 patients who are faced with limited treatment options.