Abstract: The International Staging System (ISS) and the Revised International Staging System (R-ISS) are commonly used prognostic scores in multiple myeloma (MM). These methods have significant gaps, particularly among intermediate-risk groups. The aim of this study was to improve risk stratification in newly diagnosed MM patients using data from three different trials developed by the Spanish Myeloma Group. For this, we applied an unsupervised machine learning clusterization technique on a set of clinical, biochemical and cytogenetic variables, and we identified two novel clusters of patients with significantly different survival. The prognostic precision of this clusterization was superior to those of ISS and R-ISS scores, and appeared to be particularly useful to improve risk stratification among R-ISS 2 patients. Additionally, patients assigned to the low-risk cluster in the GEM05 over 65 years trial had a significant survival benefit when treated with VMP as compared with VTD. In conclusion, we describe a simple prognostic model for newly diagnosed MM whose predictions are independent of the ISS and R-ISS scores. Notably, the model is particularly useful in order to re-classify R-ISS score 2 patients in 2 different prognostic subgroups. The combination of ISS, R-ISS and unsupervised machine learning clusterization brings a promising approximation to improve MM risk stratification.

Abstract: Patients with multiple myeloma (MM) carrying standard- or high-risk cytogenetic abnormalities (CAs) achieve similar complete response (CR) rates, but the later have inferior progression-free survival (PFS). This questions the legitimacy of CR as a treatment endpoint and represents a biological conundrum regarding the nature of tumor reservoirs that persist after therapy in high-risk MM. We used next-generation flow (NGF) cytometry to evaluate measurable residual disease (MRD) in MM patients with standard- vs high-risk CAs (n = 300 and 90, respectively) enrolled in the PETHEMA/GEM2012MENOS65 trial, and to identify mechanisms that determine MRD resistance in both patient subgroups (n = 40). The 36-month PFS rates were higher than 90% in patients with standard- or high-risk CAs achieving undetectable MRD. Persistent MRD resulted in a median PFS of ∼3 and 2 years in patients with standard- and high-risk CAs, respectively. Further use of NGF to isolate MRD, followed by whole-exome sequencing of paired diagnostic and MRD tumor cells, revealed greater clonal selection in patients with standard-risk CAs, higher genomic instability with acquisition of new mutations in high-risk MM, and no unifying genetic event driving MRD resistance. Conversely, RNA sequencing of diagnostic and MRD tumor cells uncovered the selection of MRD clones with singular transcriptional programs and reactive oxygen species–mediated MRD resistance in high-risk MM. Our study supports undetectable MRD as a treatment endpoint for patients with MM who have high-risk CAs and proposes characterizing MRD clones to understand and overcome MRD resistance. This trial is registered at www.clinicaltrials.gov as #NCT01916252.

Abstract: Background: The international criteria for definition CR, requires, among other parametres, a negative IF both in serum and urine; however, urine IF is not always performed. In the belief that this lack could bias the comparison between trials, the First Trial Independent Response Adjudication Committee (FTIRAC) recommended that patients who met all CR criteria except the availability of a urine IF should be classified as VGPR (Blood 2014; 124 [abstract 3460]) but this criteria is not always applied which may translate into differences in CR rates between trials. However, it is unknown (1) if this conversion has a real clinical basis, (2) if urine IF results alter the clinical meaning of CR, or (3) on the contrary, if patients in CR with and those without a documented negative urine IF have a similar prognosis, in which case this rule would underestimate the CR rates, increasing the biases and magnifying the problem that was intended to improve. Aim: To determine the value of urine negative IF in the definition of CR. Methods: 459 patients were enrolled into the GEM2012MENOS65phase3 trial and treated with 6 induction cycles of bortezomib, lenalidomide, and dexamethasone, HDT/ASCT and 2 consolidation courses. Evaluable patients were enrolled in a maintenance trail (NCT02406144). Excluding 6 patients who discontinued early, 453 were evaluable. At diagnosis, the M-component was detected exclusively in serum in 173 of these patients and in serum and urine in 212 patients; 68 patients had pure Bence-Jones M-protein (BJMM). The protein studies were performed in each cycle. At the time of negative IF, bone marrow aspirates were analysed for count of PCs and monitoring minimal residual disease (MRD) following EuroFlow SOPs (median limit of detection of 3x10-6).The response classifications were made according to the IMWG criteria, but we applied the FTIRAC criteria, and, patients with 〈 5% BM PCs and negative serum IF but with unavailable urine IF (or vice versa for patients with BJMM) were classified as VGPR. For the purpose of this study, we called these uncertain CR (uCR). Stringent Complete Responses were classified as CR.Median follow-up was 40 months. Results: Overall, 3774 protein evolution studieswere performed: 691 (18%) in CR, 802 (21%) in uCR and 868 (23%)in VGPR.In all patients with M-component exclusively in serum at diagnosis butwith negative serum IF after treatment, and available urine IF (174 patients, 1476 protein studies), the urine paraprotein IF detection rate was 0%. In patients with a positive M-component in both serum and urine at diagnosis, but with negative serum IF after treatment, and available urine IF (212patients, 1763 protein assessment), 11 protein evaluations in 6 patients (2.8%) tested positive in urine; in other words: in 97,2% of the patients a negative serum IF predicts for negative urine.Since MRD is a robust subrogate of depth of responses (J ClinOncol. 2017;35:2900-10), we compared MRD-verates in patients achieving CR, uCR and VGPR. Interestingly, there were no significant differences in the post-consolidation MRD-verates among patients in CR vsthose in uCR (68% vs 77%, P=.1), whereas significant differences were seen when comparing CR and uCRvs VGPR (23% in the latter; P≤.0001). Accordingly, a landmark analysis performed at HDT/ASCT, - time pointselected to improve the PFS observation time- , showed 2-year PFS rates of 88%, 87% and 77% inpatients in CR, uCR and VGPR, no differences in 2-year PFS rates between patients in CR vsuCR (P=.6) while patients in VGPR showed inferior PFS compared with those in uCR (P=.04). With this landmark, the MRD-negativity ratios are similar to those described after consolidation. Conclusions: In MM patients with M-component exclusively in serum at diagnosis, urine IF follow-up is unnecessary, while in patients with paraprotein in both serum and urine,a negative serum IF response is accompanied by a negative urinary IF in 97.8% of patients. Moreover, patients with CR but without available IF in urine display similar MRD-veand PFS rates compared withthose in CR. By contrast, MRD-veand PFS values in these patients are significantly superior to those in VGPR. Thus, our results suggest that, except for those with pure BJMM, patients fulfilling CR criteria but with unavailable urine IF should be classified as CR instead of VGPR. This data discourages the application of the FTIRAC conversion criteria. Also, the IMWG criteria for CR should be reviewed. Disclosures Rosinol: Janssen, Celgene, Amgen, Takeda: Honoraria. Puig:Janssen: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria; Celgene: Honoraria, Research Funding. Garcia-Sanz:Affimed: Research Funding. Oriol:Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Rios:Amgen, Celgene, Janssen, and Takeda: Consultancy. De La Rubia:Ablynx: Consultancy, Other: Member of Advisory Board. Mateos:Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; GSK: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; GSK: Consultancy, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. San-Miguel:Brystol-Myers Squibb: Consultancy; Celgene: Consultancy; Novartis: Consultancy; Takeda: Consultancy; Amgen: Consultancy; MSD: Consultancy; Janssen: Consultancy; Sanofi: Consultancy; Roche: Membership on an entity's Board of Directors or advisory committees. Bladé:Celgene: Honoraria; Amgen: Honoraria; Janssen: Honoraria. Lahuerta:Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Abstract: Background: The randomized PETHEMA/GEM phase III trial GEM05menos65 (www.clinicaltrials.gov NCT00461747) demonstrated that pretransplant induction therapy with VTD resulted in a significantly higher CR rate both, pretransplant and postransplant and in a significantly longer progression-free survival (PFS) when compared with thalidomide/dexamethasone (TD) and combination chemotherapy plus bortezomib (VBMCP/VBAD/B) (Rosiñol et al, Blood 2012). We report here the definitive results of the trial, ten years after the last patient was included. Methods: From April 6, 2006 to August 5, 2009, 386 patients younger than 65 years with newly diagnosed symptomatic multiple myeloma (MM) were randomized to receive three different induction regimens: six 4-week cycles of TD (thalidomide 200 mg daily; dexamethasone 40 mg on days 1-4 and 9-12) vs. six 4-week cycles of VTD (TD at identical doses plus i.v. bortezomib 1.3 mg/m2 on days 1, 4, 8 and 11) vs. combination chemotherapy plus bortezomib (4 cycles of alternating VBMCP and VBAD chemotherapy followed by two cycles of i.v. bortezomib at the usual dose of 1.3 mg/m2 on days 1,4,8,11 every 3 weeks). The duration of the induction therapy was 24 weeks in all arms. All patients were planned to undergo ASCT with high-dose melphalan at 200 mg/m2 followed by maintenance therapy with thalidomide/bortezomib (TV) vs. thalidomide (T) vs. alfa-2b-interferon (alfa2-IFN) for 3 years. One-hundred and thirty patients were allocated to VTD, 127 to TD and 129 to VBMCP/VBAD/B. Seventy out of the 330 patients (21%) with cytogenetic studies had high-risk cytogenetics [t(4;14), t(14;16) and/or 17p deletion]. Patient characteristics at diagnosis and prognostic factors such as ISS, cytogenetics and maintenance arm were similarly distributed in the 3 arms. Results: After a median follow-up of 115 months for alive patients, VTD resulted in a significantly longer PFS when compared with TD and VBMCP/VBAD/B (52 vs 28 vs 32 months, p=0.01) (Figure 1). The median overall survival (OS) was 128 vs 99 vs 93 months, respectively, with no significant differences among the 3 arms. In the overall series, the PFS was significantly shorter in patients with high-risk cytogenetics compared with patients with standard-risk (15 vs. 42 months, p=0.001). In the TD and in the VBMCP/VBAD/B arm patients with high-risk cytogenetics had a significantly shorter PFS than patients with standard-risk (7 vs 32 months, p=0.029 in TD group; 13 vs. 38 months, p=0.027 in VBMCP/VBAD/B group). However, there was no significant difference in the VTD arm (23 vs 52 months, p=0.125). Patients with high-risk cytogenetics had a significantly shorter OS in the overall series (median 38 months vs 114, p=0.0001) and this was observed in the three treatment arms: VTD median 36 months vs not reached (p=0.0001), TD median 52 months vs 113 (p=0.017), VBMCP/VBAD/B median 29 months vs 93 (p=0.01). The achievement of a negative MRD after transplant was associated with a longer PFS and OS. Thus, on an intention to treat basis, patients who had MRD negative after transplant had a significantly longer PFS (59 vs 38 months, p=0.0001) and OS (median not reached vs 102 months, p=0.001) than those who remained MRD positive after ASCT. Of interest, there are no significant differences in PFS (41 months vs 60 months, p=0.367) or OS (114 moths vs not reached, p=0.329) between patients with high-risk or standard risk cytogenetics who achieved negative MRD after transplant. By contrast, in patients with MRD positive after transplant, the PFS ( 16 months vs 38 months, p=0.006) and OS (29 months vs 113 months, p=0.001) was significantly shorter in patients with high-risk cytogenetics compared with patients with standard-risk cytogenetics. Conclusions: Our long-term results confirm that induction with VTD results in a significantly longer PFS when compared with TD and VBMCP/VBAD/B. Patients with high-risk cytogenetics who achieved postransplant MRD negative had a similar outcome than patients with standard-risk cytogenetics, while patients with high-risk cytogenetics who remain MRD positive had a dismal prognosis. Finally, the PFS of 52 months achieved with VTD is the longest ever reported in the first line treatment of younger patients with MM elegible for ASCT and support the use of VTD as the standard of care for pretransplant induction therapy. Figure 1. Figure 1. Disclosures Rosinol Dachs: Amgen: Honoraria; Celgene: Honoraria; Janssen: Honoraria. Oriol:Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Blanchard:Janssen: Honoraria. Granell:Janssen: Honoraria; Celgene: Honoraria. Mateos:GSK: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; GSK: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Martinez-Lopez:Celgene: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Vivia: Honoraria; Pfizer: Research Funding; BMS: Research Funding; Novartis: Research Funding. Alegre:Celgene: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees. Lahuerta:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees. San-Miguel:BMS: Honoraria; Roche: Honoraria; Sanofi: Honoraria; Celgene: Honoraria; Amgen: Honoraria; Janssen: Honoraria; Novartis: Honoraria. Blade:Amgen: Honoraria; Celgene: Honoraria; Janssen: Honoraria.

Abstract: Assessing measurable residual disease (MRD) has become standard with many tumors, but the clinical meaning of MRD in multiple myeloma (MM) remains uncertain, particularly when assessed by next-generation flow (NGF) cytometry. Thus, we aimed to determine the applicability and sensitivity of the flow MRD-negative criterion defined by the International Myeloma Working Group (IMWG). PATIENTS AND METHODS In the PETHEMA/GEM2012MENOS65 trial, 458 patients with newly diagnosed MM had longitudinal assessment of MRD after six induction cycles with bortezomib, lenalidomide, and dexamethasone (VRD), autologous transplantation, and two consolidation courses with VRD. MRD was assessed in 1,100 bone marrow samples from 397 patients; the 61 patients without MRD data discontinued treatment during induction and were considered MRD positive for intent-to-treat analysis. The median limit of detection achieved by NGF was 2.9 × 10 −6 . Patients received maintenance (lenalidomide ± ixazomib) according to the companion PETHEMA/GEM2014MAIN trial. RESULTS Overall, 205 (45%) of 458 patients had undetectable MRD after consolidation, and only 14 of them (7%) have experienced progression thus far; seven of these 14 displayed extraosseous plasmacytomas at diagnosis and/or relapse. Using time-dependent analysis, patients with undetectable MRD had an 82% reduction in the risk of progression or death (hazard ratio, 0.18; 95% CI, 0.11 to 0.30; P 〈 .001) and an 88% reduction in the risk of death (hazard ratio, 0.12; 95% CI, 0.05 to 0.29; P 〈 .001). Timing of undetectable MRD (after induction v intensification) had no impact on patient survival. Attaining undetectable MRD overcame poor prognostic features at diagnosis, including high-risk cytogenetics. By contrast, patients with Revised International Staging System III status and positive MRD had dismal progression-free and overall survivals (median, 14 and 17 months, respectively). Maintenance increased the rate of undetectable MRD by 17%. CONCLUSION The IMWG flow MRD-negative response criterion is highly applicable and sensitive to evaluate treatment efficacy in MM.

Abstract: The existence of patients with multiple myeloma (MM) and light-chain (AL) amyloidosis who present with a monoclonal gammopathy of undetermined significance (MGUS)–like phenotype has been hypothesized, but methods to identify this subgroup are not standardized and its clinical significance is not properly validated. PATIENTS AND METHODS An algorithm to identify patients having MGUS-like phenotype was developed on the basis of the percentages of total bone marrow (BM) plasma cells (PC) and of clonal PC within the BM PC compartment, determined at diagnosis using flow cytometry in 548 patients with MGUS and 2,011 patients with active MM. The clinical significance of the algorithm was tested and validated in 488 patients with smoldering MM, 3,870 patients with active MM and 211 patients with AL amyloidosis. RESULTS Patients with smoldering MM with MGUS-like phenotype showed significantly lower rates of disease progression (4.5% and 0% at 2 years in two independent series). There were no statistically significant differences in time to progression between treatment versus observation in these patients. In active newly diagnosed MM, MGUS-like phenotype retained independent prognostic value in multivariate analyses of progression-free survival (PFS; hazard ratio [HR], 0.49; P = .001) and overall survival (OS; HR, 0.56; P = .039), together with International Staging System, lactate dehydrogenase, cytogenetic risk, transplant eligibility, and complete remission status. Transplant-eligible patients with active MM with MGUS-like phenotype showed PFS and OS rates at 5 years of 79% and 96%, respectively. In this subgroup, there were no differences in PFS and OS according to complete remission and measurable residual disease status. Application of the algorithm in two independent series of patients with AL predicted for different survival. CONCLUSION We developed an open-access algorithm for the identification of MGUS-like patients with distinct clinical outcomes. This phenotypic classification could become part of the diagnostic workup of MM and AL amyloidosis.

Abstract: Background: Within the spectrum of monoclonal gammopathies, there are various subgroups with unique biological and clinical profiles. Namely, the presence of multiple myeloma (MM) and light-chain amyloidosis (AL) pts with MGUS-like phenotype has been hypothesized, but the criteria to identify this subgroup are poorly defined and lack clinical validation. Aim: Develop an algorithm based on a large flow cytometry dataset across the spectrum of monoclonal gammopathies, for automated identification of MM and AL pts with MGUS-like phenotype. Methods: This study included 5,114 pts with monoclonal gammopathies and available flow cytometry data on the frequency of bone marrow (BM) plasma cells (PC) and the percentages of normal and clonal PC within the BM PC compartment, at diagnosis. An algorithm to classify pts with MGUS-like phenotype was developed based on these three parameters, obtained from 548 MGUS, 393 smoldering MM (SMM) and 2,011 MM pts. Newly diagnosed MM pts were homogeneously treated according to the GEM2000 (n = 486), GEM2005MENOS65 (n = 330), GEM2005MAS65 (n = 239), GEM2010MAS65 (n = 230), GEM2012MENOS65 (n = 450) and CLARIDEX (n = 276) protocols. The prognostic value of the MGUS-like phenotype was validated in 96 SMM pts studied in Arkansas and 1,859 MM pts treated outside clinical trials in Czech Republic. The clinical significance of the algorithm was investigated in two independent series of Spanish (n = 102) and Italian (n = 105) AL pts. Results: The frequency of BM PC and of normal and clonal PC within the BM PC compartment were used to plot MGUS, SMM and MM pts in a principal component analysis (PCA). Lines defining 1.5 standard deviations of MGUS and MM pts were used as reference to classify each of the 5,114 cases. Once plotted against the dataset, individual pts were classified as MGUS-, intermediate- or MM-like, if their location in the PCA fell inside the MGUS, the overlapping or the MM reference lines, respectively. In the training SMM series, patient classification into MGUS-, intermediate- and MM-like phenotype resulted in significantly different rates of disease progression (0%, 54% and 66% at 5y, respectively; P & lt; .001). These results were validated in the Arkansas series (8%, 27% and 71% at 5y, respectively; P & lt; .001). Only 5% of SMM pts with high-risk disease according to Mayo or PETHEMA criteria had an MGUS-like phenotype, and these had virtually no risk of progression at 5y. In the training MM series, pts with MGUS-like phenotype showed significantly longer progression free (PFS) and overall survival (OS) vs the remaining pts. Median PFS was 10y vs 3y (hazard ratio [HR]: 0.46, P & lt; .001) and median OS was not reached (NR) vs 6.5y (HR: 0.48, P & lt; .001), respectively. These results were validated in the Czech Republic series with significant differences in PFS (HR: 0.45, P & lt; .001) and OS (HR: 0.38, P & lt; .001) between MGUS-like vs other MM pts. MGUS-like classification in the training MM series retained independent prognostic value in multivariate analyses of PFS (HR: 0.48, P & lt; .001) and OS (HR: 0.54, P = .033), together with ISS, LDH, cytogenetics, induction regimen, transplant-eligibility and complete remission (CR). MGUS-like pts showed similar PFS (P = .932) and OS (P = .285) regardless of having standard vs high risk cytogenetics. Notably, MGUS-like transplant-eligible MM pts treated with proteasome inhibitors, immunomodulatory drugs and corticoids during induction showed PFS and OS rates at 5y of 86% and 96%, respectively. Differences in PFS among MGUS-like MM pts achieving ≥CR vs & lt;CR were not significant (median of 13y vs 9y, respectively; P = .122), which suggests that attaining CR is not mandatory to reach long-term survival in this subgroup of pts, treated with fixed-duration regimens. Classification of AL pts into the MGUS-, intermediate- and MM-like phenotype resulted in significantly different PFS in the Spanish (median of 28, 20 and 1 months, respectively; P = .001) and Italian (median 32, 11 and 3 months, respectively; P & lt; .001) cohorts. Conclusions: We developed an algorithm that can be readily installed in clinical flow cytometry software, and requires three parameters that are routinely assessed at screening. Patient' automated classification using the algorithm was validated in large series across the spectrum of monoclonal gammopathies. Because pts with MGUS-like phenotype have a distinct clinical behavior, their identification could become part of the diagnostic workup in SMM, MM and AL. Disclosures Cedena: Janssen, Celgene and Abbvie: Honoraria. Milani: Celgene: Other: Travel support; Janssen-Cilag: Honoraria. Cordon: Cytognos SL: Research Funding. Oriol: Takeda: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Janssen: Consultancy. de la Rubia: Amgen, Bristol Myers Squibb,: Honoraria, Speakers Bureau; Celgene, Takeda, Janssen, Sanofi: Honoraria; Ablynx/Sanofi: Consultancy; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; AbbVie: Consultancy; Bristol Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel Accommodations; GSK: Consultancy; Takeda: Consultancy; Sanofi: Membership on an entity's Board of Directors or advisory committees. De Arriba: Amgen: Consultancy, Honoraria; Glaxo Smith Kline: Consultancy, Honoraria; BMS-Celgene: Consultancy, Honoraria, Speakers Bureau; Janssen: Consultancy, Honoraria, Speakers Bureau. Cabañas: Janssen: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Sanofi: Honoraria. Gonzalez De La Calle: Celgene-BMS, Janssen, Amgen: Honoraria. Rodríguez-Otero: Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Regeneron: Membership on an entity's Board of Directors or advisory committees; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Honoraria, Membership on an entity's Board of Directors or advisory committees; Kite: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS/Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel and other expenses. Hajek: Pharma MAR: Consultancy, Honoraria; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Research Funding; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding. Jimenez-Zepeda: BMS, Amgen, Takeda, Janssen: Honoraria. Palladini: Janssen Global Services: Honoraria, Other: advisory board fees; Pfizer: Honoraria; Siemens: Honoraria. Rosinol: Janssen, Celgene, Amgen and Takeda: Honoraria. Bladé Creixenti: Janssen, Celgene, Takeda, Amgen and Oncopeptides: Honoraria. Martínez-López: Janssen, BMS, Novartis, Incyte, Roche, GSK, Pfizer: Consultancy; Roche, Novartis, Incyte, Astellas, BMS: Research Funding. Mateos: Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Regeneron: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene - Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sea-Gen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria; Oncopeptides: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bluebird bio: Honoraria; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; GSK: Honoraria; Oncopeptides: Honoraria. San-Miguel: AbbVie, Amgen, Bristol-Myers Squibb, Celgene, GlaxoSmithKline, Janssen, Karyopharm, Merck Sharpe & Dohme, Novartis, Regeneron, Roche, Sanofi, SecuraBio, Takeda: Consultancy, Other: Advisory board. Paiva: Bristol-Myers Squibb-Celgene, Janssen, and Sanofi: Consultancy; Adaptive, Amgen, Bristol-Myers Squibb-Celgene, Janssen, Kite Pharma, Sanofi and Takeda: Honoraria; Celgene, EngMab, Roche, Sanofi, Takeda: Research Funding.

Abstract: Adoptive transfer of allogeneic natural killer (NK) cells is becoming a credible immunotherapy for hematological malignancies. In the present work, using an optimized expansion/activation protocol of human NK cells, we generate expanded NK cells (eNK) with increased expression of CD56 and NKp44, while maintaining that of CD16. These eNK cells exerted significant cytotoxicity against cells from 34 B-CLL patients, with only 1 sample exhibiting resistance. This sporadic resistance did not correlate with match between KIR ligands expressed by the eNK cells and the leukemic cells, while cells with match resulted sensitive to eNK cells. This suggests that KIR mismatch is not relevant when expanded NK cells are used as effectors. In addition, we found two examples of de novo resistance to eNK cell cytotoxicity during the clinical course of the disease. Resistance correlated with KIR-ligand match in one of the patients, but not in the other, and was associated with a significant increase in PD-L1 expression in the cells from both patients. Treatment of one of these patients with idelalisib correlated with the loss of PD-L1 expression and with re-sensitization to eNK cytotoxicity. We confirmed the idelalisib-induced decrease in PD-L1 expression in the B-CLL cell line Mec1 and in cultured cells from B-CLL patients. As a main conclusion, our results reinforce the feasibility of using expanded and activated allogeneic NK cells in the treatment of B-CLL.