A High Percentage of DNAM-1+ and Low Percentage of Tactile+ NK Cells at Diagnosis Correlate with Complete Response and Survival in AML: A Sub-Analysis of the Ven-a-Qui Pethema Trial

Background: Natural killer (NK) immune status in Acute Myeloid Leukemia (AML) could influence therapeutic results and natural history of the disease.

Objectives: In the phase I/II VEN-A-QUI (Clinical trials NCT04687761) clinical trial for unfit newly diagnosed AML patients (venetoclax+Quizartinib+azacytidine or low-dose cytarabine), it was planned a prospective study of NK populations and their influence in the main clinical outcomes. NK cells were analyzed at the diagnosis in a central laboratory.

Material and methods: We analyzed NK cell subpopulations based in the expression of DNAM-1, TIGIT, TACTILE, CD8, PD-1, TIM-3, LAG-3, NKp44, NKp46, NKp30, CD16, CD85j,KIR2D, NKG2C, NKG2A, CD57, CD6, CD244, NKp80, Perforin, Granulolysin and Granzyme B. We compare composite Complete Remission (CRc) results of the Venetoclax/Quizatinib with Aza or Cytarabine vs. not achieving CRc using t Student. MaxStat statistics was used to test the significant limit of those populations with a significant difference (R-statistics version 4.2.2). Survival analysis comparing significant differences between patients in CRc was performed using LogRank test and Kaplan Maier. Cox survival analysis was performed to evaluate if the presence of this populations could be an independent factor against the European Leukemia Net classification of 2017 and p53. Data of molecular characteristics were obtained with an NGS panel of 40 genes.

RESULTS: The trial included 76 ineligible patients for intensive chemotherapy (37 and 39 were in Aza and LDAC arms respectively). cCR was obtained in 39 patients (51.3%). ELN2017 risk was favorable in 8, intermediate in 15, and Adverse in 53. In 70 patients NK cell populations were analyzed (4 patients with very low percentage of NK cells, 2 with no sample at diagnosis were excluded from the study). There were significant differences between patients who achieve CRc and those who did not, according to DNAM-1 (74.4% vs 61.9, p=0.0018) and TACTILE (62% vs. 72%, p=0.02) expression on NK cells. The rest of antigens analyzed on NK cells were not significant. We found a cutoff of 62% of DNAM-1+ and less than 81% of TACTILE to differentiate populations in terms of survival using long-rank test. The number of DNAM-1 positive was 47 (60%) and TACTILE- was 55 (78%). The median OS of DNAM-1+ was better than DNAM-1− (18.4 vs 4.7 months, p=0.0001), and between TACTILE− vs TACTILE+ (17,36 vs. 4.6 months, p=0.005). Using an Cox model comparing karyotype, p53 and DNAM-1+ and TACTILE-, only DNAM-1+ was associated with better outcome (HR:0.33 (0.17-0.66) and TACTILE+ with worse (HR: 2.44 (1.20-4.99) in multivariate analysis.

Conclusions: DNAM-1(CD226) positive and TACTILE (CD96) negative NK cell populations are associated to CR and better OS. These findings need to be confirmed in larger studies. Interestingly, DNAM-1 is an activating receptor and TACTILE is an inhibitory receptor for NK cells that share the same CD155 ligand but display opposite function.