Killer cell Ig–like receptors (KIRs) bind cognate HLA class I ligands with distinct affinities, affecting NK cell licensing and inhibition. We hypothesized that differences in KIR and HLA class I genotypes predictive of varying degrees of receptor–ligand binding affinities influence clinical outcomes in autologous hematopoietic cell transplantation (AHCT) for acute myeloid leukemia (AML). Using genomic DNA from a homogeneous cohort of 125 AML patients treated with AHCT, we performed KIR and HLA class I genotyping and found that patients with a compound KIR3DL1+ and HLA-Bw4-80Thr+, HLA-Bw4-80Ile– genotype, predictive of low-affinity interactions, had a low incidence of relapse, compared with patients with a KIR3DL1+ and HLA-Bw4-80Ile+ genotype, predictive of high-affinity interactions (hazard ratio [HR], 0.22; 95% confidence interval [CI], 0.06–0.78; p = 0.02). This effect was influenced by HLA-Bw4 copy number, such that relapse progressively increased with one copy of HLA-Bw4-80Ile (HR, 1.6; 95% CI, 0.84–3.1; p = 0.15) to two to three copies (HR, 3.0; 95% CI, 1.4–6.5; p = 0.005) and progressively decreased with one to two copies of HLA-Bw4-80Thr (p = 0.13). Among KIR3DL1+ and HLA-Bw4-80Ile+ patients, a predicted low-affinity KIR2DL2/3+ and HLA-C1/C1 genotype was associated with lower relapse than a predicted high-affinity KIR2DL1+ and HLA-C2/C2 genotype (HR, 0.25; 95% CI, 0.09–0.73; p = 0.01). Similarly, a KIR3DL1+ and HLA-Bw4-80Thr+, HLA-Bw4-80Ile– genotype, or lack of KIR3DL1+ and HLA-Bw4-80Ile+ genotype, rescued KIR2DL1+ and HLA-C2/C2 patients from high relapse (p = 0.007). These findings support a role for NK cell graft-versus-leukemia activity modulated by NK cell receptor–ligand affinities in AHCT for AML.

BackgroundPhase IIb clinical trial with isatuximab (Isa)-lenalidomide (Len)-dexamethasone (Dex) showed an improved progression-free survival (PFS) in patients with relapsed or refractory multiple myeloma (RRMM), but the efficacy varied by patient. Antibody-dependent cell-mediated cytotoxicity (ADCC) by natural killer (NK) cells plays a crucial role in arbitrating antitumor activities of therapeutic-antibodies. We tested if patient-specific genetic makeup known to set NK cell functional threshold influence response to Isa-Len-Dex therapy.MethodsWe characterized 57 patients with RRMM receiving Isa-Len-Dex for polymorphisms of killer-cell immunoglobulin-like receptors (KIR), human leukocyte antigen (HLA) class I, and FCGR3A loci. In vitro ADCC assay, coincubating primary NK cells expressing specific KIR repertoire with multiple myeloma cell lines (MM cells) expressing selected HLA class I ligands, was used to confirm the identified genetic correlatives of clinical response.ResultsPatients with KIR3DL2+ and its cognate-ligand HLA-A3/11+ had superior PFS than patients missing this combination (HR=0.43; p=0.02), while patients carrying KIR2DL1+ and HLA-C2C2+ compared with to patients missing this pair showed short PFS (HR=3.54; p=0.05). Patients with KIR3DL2+ and HLA-A3/11+ plus high-affinity FCGR3A-158V allele showed the most prolonged PFS (HR=0.35; p=0.007). Consistent with these clinical data, mechanistic experiments demonstrated that NK cells expressing KIR3DL2 trigger greater ADCC when MM cells express HLA-A3/11. Inversely, NK cells expressing KIR2DL1 do not kill if MM cells express the HLA-C2C2 ligand. NK cells expressing high-affinity FCGR3A-158VV-induced greater ADCC compared with those with low-affinity FCGR3A-158FF.ConclusionsOur results suggest that KIR3DL2+ and HLA-A3/11+ with FCGR3A-158V markers lead to enhanced Isa-dependent NK-mediated cytolysis against MM cells and results in improved PFS in patients with RRMM treated by Isa-Len-Dex. Moreover, the presence of KIR2DL1+ and HLA-C2C2+ identifies patients who may have a lower response to Isa-Len-Dex therapy linked to a reduced NK-mediated ADCC. These biomarkers could potentially identify, via precision medicine, patients more likely to respond to Isa-Len-Dex immunotherapy.Trial registration numberNCT01749969.

SAR650984 (SAR) is a humanized IgG1 monoclonal antibody that binds selectively to the human CD38 receptor. TCD11863 (TCD) is a phase Ib trial evaluating the combination of SAR with lenalidomide (LEN) and dexamethasone (Dex) in relapsed/refractory multiple myeloma (RRMM) [NCT01749969]. Because natural killer (NK) cells contribute to antibody-dependent cellular cytotoxicity, we hypothesized that immunogenetic factors contributing to NK cell function would influence clinical activity among RRMM patients treated with SAR/LEN/Dex. We therefore prospectively performed KIR and HLA class I genotyping on 31 RRMM patients enrolled in TCD. We used the typing data to stratify patients based on predicted differences in KIR3DL1, HLA-Bw4 receptor-ligand binding affinities. We used the Kaplan-Meier method to estimate probabilities of progression-free survival (PFS) and time to progression (TTP) among all 31 treated patients, with the log-rank test to evaluate differences in survival distributions based on patient KIR and HLA genotype status, the cox proportional hazard model to examine the association of the hazard of failure with genotype status, and the Fischer's exact test to compare overall response rates (ORR) among 28 evaluable patients. P-values are provided for exploratory purpose, since the study was not powered for formal comparison of efficacy variables by genotype subgroup. Of the 31 patients, 12 had a high-affinity KIR3DL1,HLA-B Bw4-80Ile compound genotype (including 3 with both HLA-A and HLA-BBw4-80Ile), and 19 lacked the KIR3DL1,HLA-B Bw4-80Ile genotype, with 7 of these 19 patients possessing a low-affinity KIR3DL1, HLA-Bw4-80Thr genotype (including 1 with HLA-ABw4-80Ile), 7 with a missing ligand or receptor genotype, and 5 with a KIR3DL1, HLA-ABw4-80Ile genotype not containing other HLA-B Bw4 alleles. Presence of a high-affinity KIR3DL1,HLA-B Bw4-80Ile genotype (n=12, 10 evaluable for ORR) was associated with high ORR and prolonged TTP and PFS relative to patients lacking KIR3DL1,HLA-B Bw4-80Ile (n=19, 18 evaluable for ORR; 90% ORR vs. 56%, P=0.10; TTP HR 0.11, [95% CI] 0.08-0.68, P<0.01; PFS HR 0.22, [95% CI] 0.05-0.98, P=0.03). The benefit of KIR3DL1,HLA-B Bw4-80Ile varied with gene dose, such that the proportion of patients remaining on treatment increased with increasing copy number of HLA-B Bw4-80Ile from 0 (n=19) to 1 (n=8) to 2 (n=4) copies, with 21% remaining on treatment at 6 months vs. 50% vs. 100% (TTP P=0.02). Because HLA-A Bw4-80Ile ligands bind KIR3DL1 with different strength and specificity than HLA-B Bw4-80Ile ligands, we separated patients with KIR3DL1, HLA-ABw4-80Ile from patients with KIR3DL1, HLA-BBw4-80Ile and found a specific association of prolonged PFS among patients with a pure high-affinity KIR3DL1,HLA-B Bw4-80Ile genotype (n=9; 7 patients remain on treatment at 6 months, 2 AEs), compared with patients with a pure KIR3DL1, HLA-A Bw4-80Ile genotype (n=5; 2 on treatment at 6 months, 3 PDs), a KIR3DL1, HLA-ABw4-80Ile genotype containing other HLA-B Bw4 alleles (n=4), a pure low-affinity KIR3DL1, HLA-Bw4-80Thr genotype (n=6; 2 on treatment at 6 months, 3 PDs, and 1 AE), and a missing KIR3DL1 ligand or receptor genotype (n=7; 3 on treatment at 6 months, 3 PDs, and 1 AE) [PFS P=0.02]. While the number of prior therapies (2-4 vs. 5-7 vs. 8-12, P=0.02) and ISS stage at the start of treatment (stage I to III, P<0.01) also influenced PFS, possession of KIR3DL1,HLA-B Bw4-80Ile was associated with prolonged PFS within each of these subgroups. In summary, a KIR3DL1, HLA-B Bw4-80Ile genotype predictive of high-affinity NK cell receptor-ligand interactions and potent NK cell licensing correlated with increased ORR and PFS among patients treated with SAR/LEN/Dex, although the small sample size requires validation in future studies. Disclosures Martin: Sanofi: Research Funding. Venstrom:Sanofi Oncology: Research Funding.