Translational development and first-in-human compassionate infusion of NK-92 cells expressing a CD5-based chimeric antigen receptor (SRCD5CAR-NK-92) in a patient with multidrug-resistant fusariosis

Introduction Invasive fungal infections (IFI) remain a major therapeutic challenge due to limited antifungal options, emergence of multidrug-resistant (MDR) strains and high mortality rates. This has turned up the development of immune-based therapies to restore and/or enhance anti-fungal immune responses into a clinical priority. This is in line with the recent demonstration that antifungal activity of primary (cord blood-derived) NK cells can be potentiated by endowing them with a CD5-based second-generation chimeric antigen receptor (SRCD5CAR) targeting β-glucans, a constitutive and broadly distributed component of fungal cell walls. Building on this, we aimed at exploring whether the reported constitutive antifungal activity of leukemia-derived NK-92 cells can also be potentiated by engineering them for further potential use as a homogeneous and ready-to-use source of allogeneic cells for adoptive transfer therapy in IFI. Methods NK-92 cells lentivirally transduced and selected for stable and high-level expression of the SRCD5CAR for further testing in in vitro fungal killing assays, as well as in an in vivo model of fungal infection. Results SRCD5CAR-NK-92 cells showed superior antifungal activity than untransduced NK-92 cell counterparts. SRCD5CAR-NK-92 cells also exhibited superior activity against a MDR Fusarium petroliphilum isolate from a patient undergoing a hematological malignancy and devoid of alternative therapeutic options. Following compassionate use approval, the patient received escalating intravenous infusions of irradiated SRCD5CAR-NK-92 cells at 2-5 day intervals, without significant local or systemic adverse effects (e.g., cytokine storm or alloreactivity). Discussion Despite the patient ultimately succumbed due to progression of the underlying hematological malignancy, this represents first-in-human use of SRCD5CAR-NK-92 cells in the context of a severe MDR IFI. The results highlight its potential as a safe and off-the-shelf therapeutic strategy, while underscoring the need for further investigation on efficacy and long-term outcomes.