Summary:
CD19 directed CAR-T cells have transformed the treatment landscape of B-cell lymphoid malignancies.
However, despite high initial complete remission rates, relapses occur within the first year of therapy in
approximately 50% of patients who receive commercially available autologous CAR19 T-cells. Relapses can be
classified into two patterns: CD19-positive relapse related to CAR T-cell exhaustion and senescence, or CD19-
negative relapse related to target antigen loss. Patients who relapse after CAR19 T-cell therapy have poor
prognosis; hence, there is an urgent need to develop the next-generation of CAR engineered immune effector
cells that target tumors with efficacy and with minimal toxicity. There is growing interest in natural killer (NK) cells
as a candidate for CAR therapy as they may prevent antigen escape through their innate ability to kill tumor cells
and they are safe and well-suited for use in the allogeneic therapy setting. In a first-in-human study, our group
showed the safety and promising activity of cord blood (CB) derived CAR-NK cells targeting CD19 in patients
with B-lymphoid malignancies (Liu et al NEJM 2020). This proposal aims to build on this platform to develop the
next-generation NK cell therapies by enhancing NK cell potency and persistence through optimal costimulatory
signaling, cytokine armoring and checkpoint inhibition. We have identified CD70, as a novel therapeutic target
in patients with B-NHL after CAR19 T-cell failure and developed a novel strategy to target CD70 by genetically
modifying CB-NK cells with a retroviral vector (iC9-CD27-DAP10-CD3¿-IL-15) that incorporates (i) the gene for
a truncated human CD27 (the natural receptor for CD70) to redirect their specificity; (ii) DAP10 as an NK-specific
costimulatory domain linked to a CD3¿ signaling endodomain; (iii) IL-15 to support their survival and proliferation,
and (iv) inducible caspase-9 (iC9) as a suicide gene. Our preliminary data show the efficacy and safety of this
approach in vitro and in vivo and support its translation to the clinic. In addition, we have developed a robust
strategy to cryopreserve CAR-NK cells, allowing for the generation of a biobank of off-the-shelf engineered NK
cells, thus reducing cost and increasing accessibility. Finally, we have devised a novel strategy to target the
immune checkpoint CIS in our CAR-NK cells to modulate their metabolic fitness and potency. We hypothesize
that targeting CD70 with iC9/CAR27D10¿/IL-15 NK cells will greatly improve outcomes in patients with NHL after
CAR19 T-cell failure and that by targeting the immune checkpoint CIS we can further enhance the CAR-NK cells’
metabolic fitness and potency. These concepts will be evaluated in three specific aims: In Aim 1 we will conduct
a Phase I/II clinical trial to test the safety and efficacy of iC9/CAR27D10¿/IL-15 NK cells in patients with CD70+
NHL who have failed CAR19 T-cell therapy (FDA approved, IND #27757). In Aim 2 we will apply innovative
single-cell proteomic and transcriptomic studies to comprehensively characterize the fate of the CAR-NK cells
and to identify key mechanisms of efficacy and resistance. In Aim 3, we will perform mechanistic studies to
elucidate how CIS deletion enhances the metabolic fitness of CAR-NK cells and will perform IND enabling studies
in preparation for the next-generation clinical studies testing CIS deficient iC9/CAR27D10¿/IL-15 NK cells.