A First-in-Human Dose Escalation Clinical Trial of Engineered Natural Killer Cell Therapy in Non-Small Cell Lung Cancer Patients Refractory to Immune Check Point Inhibitors

Background: Tumor reactive or activated-by-cytokine killers (TRACK) are PD-L1+ highly cytolytic natural killer (NK) cells derived from umbilical cord blood NK cells that are engineered to express soluble IL15 (sIL15). sIL15_TRACK NK cells have shown promise in preclinical studies against human non-small cell lung cancer (NSCLC) (PMID: 38572955). Here we demonstrate sIL15_TRACK NK cells traffic to the patients' solid tumor site, survive at the tumor site and retain cytotoxic function at the tumor site. Three of six patients, all with progressive disease at the time of study enrollment, achieved stable disease following the infusions of sIL15_TRACK NK cells.

Methods: This first-in-human phase 1 trial (NCT05334329) evaluated the initial safety, tolerability, and preliminary efficacy of unmatched, allogeneic, off-the-shelf sIL15_TRACK NK cells in six patients with advanced, previously treated NSCLC that were relapsed from or refractory to chemotherapy, refractory to immune checkpoint inhibition, and progressing at the time of enrollment. Patients received a standard lymphodepletion regimen (LDR) followed by 4 or 8 weekly infusions of sIL15_TRACK NK cells at one of two dose levels. NK cell persistence and cytotoxic activity were monitored using droplet digital PCR (ddPCR), flow cytometry, and immunofluorescent staining of a tumor biopsy.

Results: The sIL15_TRACK NK cell therapy was delivered in the outpatient setting, was well-tolerated without severe adverse events related to the therapy. Common grade 1-2 toxicities included fatigue, nausea, and diarrhea, while grade 3-4 hematologic toxicities were likely related to the standard LDR. Pharmacokinetic studies demonstrated that sIL15_TRACK NK cells were measurable in blood hours after infusion and peak measurements increased weekly, suggesting an absence of host rejection even during the second cycle where cyclophosphamide was administered without fludarabine for the LDR. sIL15_TRACK NK cells were observed in a lung tumor biopsy 7 days following the final infusion, confirming their sustainment and tumor-homing ability. The engineered sIL15_TRACK NK cells express several cell activating receptors (e.g., NKG2D, DNAM-1, and NKp30) that bind to cognate ligands that we show to be expressed on a NSCLC patient biopsy (e.g., MICA/B, CD112, and BAG6, respectively), and retain their cytolytic function following isolation from the lung tumor tissue. At two low doses of cells tested (1.5 × 10⁶ and 4.0 × 10⁶ transduced cells/kg), three out of six patients (50%) achieved disease stabilization as best response on repeat imaging, while the remaining three showed progressive disease.

Conclusion: Unmatched, allogeneic, off-the-shelf sIL15_TRACK NK cell therapy demonstrated a favorable safety profile and showed preliminary efficacy in stabilizing disease in a subset of patients with advanced and progressive NSCLC. The ability of engineered sIL15_TRACK NK cells to express activating receptors, home to tumor sites that express their cognate ligands, and retain cytolytic activity after infusion underscores their potential as a novel immunotherapeutic approach in solid tumors. Additional dose escalation cohorts and co-administration with atezolizumab are planned for a second stage of this trial.

Bruno:CytoImmune Therapeutics: Current Employment. Zhang:CytoImmune Therapeutics: Current Employment. Romeu-Bonilla:CytoImmune Therapeutics: Current Employment. Butt:CytoImmune Therapeutics: Current Employment. Forman:Allogene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Lixte Bio: Consultancy, Membership on an entity's Board of Directors or advisory committees. Caligiuri:CytoImmune Therapeutics: Consultancy, Current equity holder in private company, Other: Co-Founder; OncoC4: Consultancy, Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; Sumitomo Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; Beigene: Current equity holder in publicly-traded company; Vertex Pharmaceuticals Inc: Current equity holder in publicly-traded company. Yu:CytoImmune Therapeutics: Consultancy, Current equity holder in private company, Other: Co-Founder.