WUN101-01: First in Human Human (FIH) Phase 1 Study of WU-NK-101 (W-NK1) in Patients with Relapsed or Refractory (R/R) Acute Myeloid Leukemia (AML)

W-NK1 is a non-engineered, allogeneic drug product (DP) derived from healthy adult PBMCs and produced through a scalable GMP process. We have previously shown that this novel DP overcomes limitations of current cell therapies: restricted trafficking to and persistence in the tumor microenvironment (TME), susceptibility to hypoxia, scarcity of nutrients, and established immunosuppressive circuits (Rutella, et al. ASH 2023). W-NK1’s enhanced functionality is attributed to its unique properties which include elevated activating receptors, effector molecules, and cell adhesion markers, as well as its remarkable capacity to adapt metabolically to nutrient availability. As a living drug, W-NK1 exemplifies the adaptability necessary to effectively respond to the complex and dynamic conditions of the TME. Herein, we present data from Dose Escalation phase of the FIH study in patients with R/R AML (NCT05470140).

Following lymphodepleting chemotherapy, patients (pts) received 3 doses (Days 1, 8, and 15 of a 28-day cycle) of W-NK1 at 300 million (M) cells dose level (DL1), 900M (DL2), and 1800M (DL3) in Dose Escalation (DE), with IL-2 (1 MIU/m² QOD) support. Pharmacokinetic (PK) and pharmacodynamic (PD) analysis was performed by monitoring variant allele frequency of donor-specific SNPs and AML-defining mutations in peripheral blood (PB) samples (N=9). For cases with available HLA-based discrimination, we examined the persistence of W-NK1 in patient PB samples by flow cytometry (N=4) and evaluated the post-infusion phenotype when sufficient W-NK1 were identified (N=1). Bone marrow (BM) samples were assessed for NK infiltration by immunofluorescence (N=3). Additionally, biodistribution and persistence of W-NK1 was evaluated in pre-clinical in vivo models using near infrared (NiR) imaging and flow cytometry (N=10).

At the end of DE, 9 pts were treated (3 at each DL); DL3 was the maximum administered dose. W-NK1 demonstrated a manageable safety profile with only 1 severe treatment-related adverse event (Grade [G] ≥ 3 anemia; 11%). Cytokine Release Syndrome was reported in 4 (44.4%) pts, all G1, typically occurring the day of first or second infusion, a median duration of 2 days, and managed to complete resolution with antipyretics +/- tocilizumab. No ICANS or GvHD were reported. Prolonged pancytopenia in the absence of disease was not observed and there were no reported DLTs. All but 1 death was due to disease progression; 1 death was secondary to a road traffic accident and unrelated to the study therapy. All 9 pts were evaluable for response. While no responses were noted at DL1, all pts had transient reduction of PB blasts. At DL≥2, all but one pt showed a decrease in BM blasts, median reduction 50% (range -100 to 47), with an ORR of 50% (3/6; 2 CRi, and 1 PR).

PK/PD analysis demonstrated a mean expansion of 860-fold (range 12-6336) of W-NK1 in vivo, with persistence through D17, with concurrent elimination of circulating AML blasts. Notably, in some pts D28 BM biopsies showed increased CD56 staining compared to the BL, with a significant reduction of AML blasts, suggesting W-NK1 traffics to and persists in the BM beyond the PB. Moreover, phenotypic analysis of W-NK1 in vivo showed increasing expression of chemokine receptors, CCR5, CX3CR1, and CXCR3 over time compared to the administered DP. These features could facilitate biodistribution into peripheral tissues, as also suggested by our prior findings from pre-clinical studies. Whole-body NiR imaging of mice treated with labeled W-NK1 revealed rapid migration and persistence into secondary lymphoid organs, including the BM, spleen, and lymph nodes, in contrast to its limited presence in PB. These results highlight the challenges of relying on PB monitoring alone for PK analysis, which may not capture the full extent of persistence. Phenotypic analysis of W-NK1 from sequential PB samples noted increased expression of key cytotoxic and maturation markers including CD16, NKp44, 2B4, NKp80, CD45RA and KIR receptors compared to the DP. These data suggest that W-NK1 continues to mature into a functionally competent and cytotoxic effector cell as it expands in AML patients.

Overall, W-NK1 has demonstrated a tolerable and manageable safety profile with preliminary evidence of anti-tumor activity. Furthermore, our study highlights the evolution, expansion, and persistence of W-NK1 in patients with AML, suggesting W-NK1 as a best-in-class NK cell therapy.