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Low-affinity immunoglobulin gamma Fc region receptor III-B (FcγRIIIB) deficiency is present in ˜0·05% of the general population. Among our patients, FcγRIIIB deficiency was less frequent in those with immune-system disorders (one of 1815 patients, 0·05%) than in those with blood disorders (nine of 2147 patients, 0·42%, P = 0·023): mainly primary immune thrombocytopenia (4·34%), therapy related myeloid neoplasms (1·16%) and myelodysplastic syndrome with excess blasts (1·28%). Four of the nine (44·4%) patients with blood disorders were diagnosed with or quickly evolved to acute myeloid leukaemia (AML), suggesting that FcγRIIIB deficiency could be an adverse prognostic factor for progression to AML that should be confirmed in large multicentre studies.

Standard risk stratification (sRisk) guides clinical management in monoclonal gammopathy of undetermined significance (MGUS), smoldering multiple myeloma (SMM) and multiple myeloma (MM). Nonetheless, clinical results are considerably heterogeneous among patients with similar risk status. Blood and bone marrow samples from 276 MGUS, 56 SMM and 242 MM in regular clinical practice were analyzed at diagnosis by flow cytometry. Higher levels of aberrant circulating plasma cells (cPC) (> 0.0035% of leukocytes), combined with albumin, beta2-microglobuline and lactate-dehydrogenase levels, offered minimally-invasive risk stratification (RcPC) with results comparable to sRisk. RcPC and sRisk 10-year progression-free-survival (10y-PFS) rates were: 93.8% vs. 95.1% for low-risk, 78.4% vs. 81.7% for intermediate-risk and 50.0% vs. 47.8% for high-risk MGUS; 58.3% vs. 57.8% low-risk, 44.4% vs. 45.8% intermediate-risk and 8.9% vs. 15.0% high-risk SMM; and 44.4% vs. 44.4% low-risk, 36.1% vs. 36.8% intermediate-risk, and 13.3% vs. 16.2% high-risk MM. Circulating-PC > 0.0035% vs. cPC 0.0035% identified MGUS, SMM and MM patients at higher risk of progression or death and predicted a cohort of patients that after relapse from stringent complete response showed shorter OS. These patients could benefit from early consolidation therapy, tandem ASCT or intensive maintenance.

Proliferation and apoptosis of neoplastic cells are prognostic biomarkers in plasma cell neoplasms (PCNs). The prognostic capacity of proliferation to apoptosis ratio (Ratio-PA) in the era of immunomodulatory treatments is re-evaluated in 316 gammopathy of undetermined significance (MGUS), 57 smoldering multiple myeloma (SMM), and 266 multiple myeloma (MM) patients. Ratio-PA of 0.77 ± 0.12, 1.94 ± 0.52, and 11.2 ± 0.7 (p &lt, 0.0001) were observed in MGUS, SMM, and MM patients. Ten-year overall survival (10y-OS) rates for patients with low/high Ratio-PA were 93.5%/77.3% p &lt, 0.0001) for MGUS, 82.5%/64.7% (p &lt, 0.05) for SMM, and 62.3%/47.0% (p &lt, 0.05) for MM. For patients with low, intermediate, and high risk, 10y-OS for low/high Ratio-PA were 95.5%/72.9% (p &lt, 0.0001), 74.2%/50.4% (p &lt, 0.0001), and 35.3%/20.0% (p = 0.836), respectively. Ratio-PA was an independent prognostic factor for OS (HR = 2.119, p &lt, 0.0001, Harrell-C-statistic = 0.7440 ± 0.0194) when co-analyzed with sex, age, and standard risk. In patients with Ratio-PAhigh, only first-line therapy with VRd/VTd, but not PAD/VCD, coupled with ASCT was associated with high 10y-OS (82.7%). Tumor cell Ratio-PA estimated at diagnosis offers a prognostic biomarker that complements standard risk stratification and helps to guide the clinical management of pre-malignant and symptomatic PCNs. Every effort should be made to provide first-line therapies including VTd or VRd associated with ASCT to patients with Ratio-PAhigh at higher risk of progression and death.

Missing self recognition makes cancer sensitive to natural killer cell (NKc) reactivity. However, this model disregards the NKc licensing effect, which highly increases NKc reactivity through interactions of inhibitory killer cell immunoglobulin-like receptors (iKIR) with their cognate HLA-I ligands. The influence of iKIR/HLA-ligand (HLA-C1/C2) licensing interactions on the susceptibility to and progression of plasma cell (PC) dyscrasias was evaluated in 164 Caucasian patients and 286 controls. Compared to controls, myeloma accumulates KIR2DL1−L2+L3− genotypes (2.8% vs. 13.2%, p < 0.01, OR = 5.29) and less diverse peripheral repertoires of NKc clones. Less diverse and weaker-affinity repertoires of iKIR2D/HLA-C licensing interactions increased myeloma susceptibility. Thus, the complete absence of conventional iKIR2D/HLA-C licensing interactions (KIR2DL1−L2+L3−/C2C2, 2.56% vs. 0.35%; p < 0.05; OR = 15.014), single-KIR2DL3+/C1+ (20.51% vs. 10.84%; p < 0.05; OR = 2.795) and single-KIR2DL2+/C1+ (12.82% vs. 4.9%; p < 0.01; OR = 5.18) interactions were over-represented in myeloma, compared to controls. Additionally, KIR2DL1−L2+L3− (20% vs. 83%, p < 0.00001) as well as KIR3DL1− (23% vs. 82%, p < 0.00001) genotypes had a dramatic negative impact on the 3-y progression-free survival (PFS), particularly in patients with low-tumor burden. Remarkably, myeloma-PCs, compared to K562 and other hematological cancers, showed substantial over-expression of HLA-I (“increasing-self” instead of missing-self), including HLA-C, and mild expression of ligands for NKc activating receptors (aRec) CD112, CD155, ULBP-1 and MICA/B, which apparently renders myeloma-PCs susceptible to lysis mainly by licensed NKc. KIR2DL1−L2+L3−/C2C2 patients (with no conventional iKIR2D/HLA-C licensing interactions) lyse K562 but barely lyse myeloma-PCs (4% vs. 15%; p < 0.05, compared to controls). These results support a model where immunosurveillance of no-missing-self cancers, e.g., myeloma, mainly depends on NKc licensing.