ALBERT

Description: In MM patients relapsing after MRD-negativity, the disease could reemerge from immature cells or from undetectable MRD. However, it remains unknown if immature cells have the same genetic background as MM plasma cells (PCs), as well as the amount of MRD that persists below the limit of detection (LOD) of next-generation techniques. To obtain further insight, we compared the biological landscape of MM PCs at diagnosis to that of CD34 progenitors, B cells and normal PCs isolated from patients with negative MRD by next-generation flow (NGF) after treatment. We performed whole-exome sequencing (WES, mean depth: 90x) with the 10XGenomics Exome Solution for low DNA-input as well as deep NGS of B-cell receptor immunoglobulin (BcR IG) gene rearrangements (mean, 69,975 sequences), in a total of 68 cell-samples isolated from the bone marrow (BM) of 7 MM patients with MRD-negativity by EuroFlow NGF after induction with VRD and auto-transplant (GEM2012MENOS65 trial). Patients with negative MRD were intentionally selected to avoid contamination with MM PCs during sorting of CD34 progenitors, B-cell precursors, mature B cells and normal PCs after induction and transplant. We investigated in these populations the presence of somatic mutations and clonotypic BcR Ig rearrangements detectable in MM PCs sorted at diagnosis, using peripheral blood T cells as germline control. We also performed WES in matched diagnostic MM PCs and MRD cells persisting after VRD induction in 14 cases as control. In another 6 patients with untreated MM, we performed single-cell RNA and BcR IG sequencing (scRNA/BcRIGseq) of total BM B cells and PCs (n=16,380) to investigate before treatment, if the clonotypic BcR IG sequence of MM PCs was detectable in other B cell stages defined by their molecular phenotype. We used multidimensional flow cytometry (MFC) to investigate the frequency of B cell clonality in BM samples from a larger series of 195 newly-diagnosed MM patients, prospectively enrolled in the GEM-CLARIDEX trial. Somatic mutations present in diagnostic MM PCs were detectable in the lymphopoiesis of 5/7 patients achieving MRD-negativity after treatment. In one case, out of 55 mutations present in diagnostic MM PCs, a single mutation in PCSK1N (VAF: 0.30) was detectable in normal PCs. In the other four patients, a total of 85 mutations were present in MM PCs and up to 10 (median VAF, 0.16) were found all the way from CD34 progenitors into B-cell precursors, mature B cells and normal PCs, but not in T cells. Of note, most mutations were reproducibly detected in each cell type after induction and after transplant. All somatic mutations shared by MM PCs and normal cells were non-recurrent, and genes recurrently mutated in MM (eg. ACTG1, ATM, DIS3, FAM46C, KRAS, LTB, MAX, TRAF3) were found in MM PCs but never in normal cells. Copy number alterations (CNA) were found only in MM PCs. By contrast, up to 513/827 (62%) mutations and 48/67 (72%) CNA were detectable in matched diagnostic MM PCs and persistent MRD cells, indicating that the few somatic variants present in normal cells were unlikely related to contaminating MRD below NGF's LOD. Accordingly, MM clonotypic BcR IG rearrangements were detectable in normal PCs (4/7patients) and in immature B cells (5/7 patients) but at much lower frequencies (mean of 0.02% in both). Of note, 9 additional clonotypes (mean 8.4%) were found in MM PCs of 5/7 patients (range, 1-3). scRNR/BcRIGseq unveiled that clonotypic cells were confined mostly but not entirely within PC clusters, and that in 1 patient another clonotype was detectable in mature B cells. Accordingly, using MFC we found in a larger series that 25/195 (13%) of newly-diagnosed MM patients display B-cell clonality (median of 0.7% BM clonal B cells, range 0.02%-6.3%). In conclusion, we show for the first time that MM patients bear somatic mutations in CD34 progenitors that specifically differentiate into the B cell lineage, likely before the disease onset. Because diagnostic, MRD (and relapse) MM PCs display great genetic similarity, these results suggest that undetectable MRD

Description: Chronic myelomonocytic Leukemia (CMML) is a heterogeneous clonal disorder highly resistant to the few therapies that are available nowadays. There is increasing evidence to suggest that Programmed Death-1 (PD-1), and its major ligand Programmed Death Ligand-1 (PD-L1), are involved in immune suppression and disease progression, are highly expressed in many hematological malignancies, and can be involved in MDS pathogenesis and resistance mechanisms to hypomethylating agents. However, the expression of PD-1 and PD-L1 is not widely explored in CMML. Different types of monocytes based on CD14 and CD16 expression show different genetic profiles and functions, having different distribution in several conditions, including malignancy. In our study, we studied the expression of PD-1 and PD-L1 in the peripheral blood (PB) monocytic compartment of patients with CMML using flow cytometry , to better understand their potential role in the pathogenesis of the disease, and as a basis for the evaluation of this pathway for the development of future immunotherapy strategies. Peripheral blood samples from 16 CMML, and age matched normal (n=10) and reactive (n=9) monocytosis (〉1 x109 /L) were studied. Two hundred µl of each PB sample were stained with an 8-color panel of monoclonal antibodies (CD16-FITC, CD64-PE, PD1-PCP5.5, PDL1-PC7, CD300-APC, CD14-APCH7, HLADR-V450 and CD45-OC515). A minimum of 1x 106 events were acquired by FACSCanto II (BD Biosciences, San Jose, USA) and the data was analyzed with the Infinicyt software (Cytognos SL, Spain). Monocytic population was selected first on the automated population separator plot and confirmed by the expression of CD64 and HLADR expression. Lymphocytes were used as the internal control. Three types of monocytes were defined based on the CD14 and CD16 expression, as previously described. As expected, CMML type 1 patients had higher absolute monocyte counts in PB than reactive and normal cases (p=0.001), and higher percentage of monocytic cells by flow (0.001). The distribution (median) of the monocytic subpopulations based on CD14 and CD16 expression among the monocytic compartment in PB of CMML, reactive and normal cases, respectively, was as follows: "classical"(CD14+CD16-) were of 98%, 90% and 85% (p

Description: Introduction: The GEM-CESAR trial is a potentially curative strategy for high-risk smoldering multiple myeloma (HRsMM) patients in which the primary endpoint is the assessment of bone marrow minimal residual disease negativity by next generation flow (NGF). However, alternative methods of tumor burden evaluation in serum, like Quantitative Immunoprecipitation Mass Spectrometry (QIP-MS), a polyclonal antibody-based technology to identify intact immunoglobulins, have been also evaluated. Patients and Methods: Ninety HRsMM patients included in the GEM-CESAR trial received six 4-weeks cycles of carfilzomib, lenalidomide and dexamethasone followed by high dose melphalan and ASCT and 2 further cycles of consolidation with the same regimen. All patients received maintenance with lenalidomide up to 2 years. SPEP and IFE were performed using standard procedures and MRD was analyzed by flow cytometry following EuroFlow recommendations. QIP-MS assessment has been previously described (1) and allowed us the characterization of the isotype of each Ig trough immunoprecipitation with paramagnetic beads as well as the measurement of the molecular mass of each Ig for each specific patient, with enough precision and accuracy to establish clonality. Standard response assignment was carried out as per the IMWG guidelines. Results: First, we confirmed the higher sensitivity of QIP-MS to identify the presence of a serum M-spike as compared to conventional protein immunofixation electrophoresis methods. Amongst patients in CR, QIP-MS identified the M-spike in 18/30 (60%) post-induction, 18/47(38%) post-ASCT and 25/58(43%) post-consolidation. Interestingly, similar results were obtained with MRD-NGF post-induction [17/30(57%)] and post-ASCT [15/47(32%)] although the positive rate post-consolidation [15/58(26%)] was higher with QIP-MS. Then, we analyzed the overall concordance between the results obtained with QIP-MS and MRD-NGF at the three timepoints of disease evaluation, finding an overall concordance of 81% post-induction (n=76), 70% post-transplant (n=76) and 68% post-consolidation (n=77). Thus, when compared to the results of MRD-NGF, QIP-MS demonstrated sensitivities of 100%, 79% and 77% post-induction, post-ASCT and post-consolidation, and negative predictive values (NPV) of 100%, 79% and 82% at each respective time-point. (P 〈 0,0001; P = 0,0004; P = =,0012) Evaluation of discrepant cases showed 14 out of 22 MRD-NGF-negative patients post-induction for whom QIP-MS identified a M-spike; in some cases (i.e. IgG MM isotype) this may be related to a longer immunoglobulin half-life. There were no cases with detectable disease by NGF but QIP-MS negative. By contrast, post-ASCT, QIP-MS was negative in seven MRD-positive patients, two of whom became MRD-NGF-negative after consolidation; at last follow-up, none of them have progressed. On the other hand, sixteen patients with negative MRD-NGF after ASCT had a detectable M-spike by mass spectrometry. Of note, the M-spike became undetectable after consolidation in six out of these 16 patients. Post-consolidation, there were 7 patients in which MRD-NGF was positive but QIP-MS negative: MRD evaluation during maintenance is pending but none of them have so far progressed. By contrast, there were 18 patients with the M-spike detectable by QIP-MS but MRD-NGF negative: follow-up of these patients will address their outcome but, the only patient that has progressed so far had MRD-NGF negative post-induction, becoming positive post-transplant and consolidation, but the M-spike was detectable by QIP-MS throughout. Conclusions: M-spike monitoring by QIP-MS shows a moderate concordance with the MRD assessment by NGF in this group of HRsMM homogeneously treated. Longer follow-up will allow us to unravel the outcome of discordant cases and to define the specificity of QIP-MS and its complementary value to NGF. North S, Barnidge D, Brusseau S, Patel R, Haselton M, Du Chateau B, et al. QIP-MS: A specific, sensitive, accurate, and quantitative alternative to electrophoresis that can identify endogenous m-proteins and distinguish them from therapeutic monoclonal antibodies in patients being treated for multiple myeloma. Clinica Chimica Acta 2019;493:S433. Disclosures Puig: Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Research Funding; The Binding Site: Honoraria; Takeda, Amgen: Consultancy, Honoraria. Mateos:Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive: Honoraria; GSK: Membership on an entity's Board of Directors or advisory committees; Pharmamar: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Janssen: 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; EDO: Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Paiva:Amgen, Bristol-Myers Squibb, Celgene, Janssen, Merck, Novartis, Roche, and Sanofi; unrestricted grants from Celgene, EngMab, Sanofi, and Takeda; and consultancy for Celgene, Janssen, and Sanofi: Consultancy, Honoraria, Research Funding, Speakers Bureau. Rodriguez Otero:Takeda: Consultancy; Kite Pharma: Consultancy; BMS: Honoraria; Celgene Corporation: Consultancy, Honoraria, Speakers Bureau; Janssen: Consultancy, Honoraria. Oriol:Celgene, Amgen, Takeda, Jansse: Consultancy, Speakers Bureau. Rios:Janssen: 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. Alegre:Celgene, Amgen, Janssen, Takeda: Membership on an entity's Board of Directors or advisory committees. de la Rubia:AbbVie: Consultancy; Janssen: Consultancy; Amgen: Consultancy; Celgene: Consultancy; Takeda: Consultancy. De Arriba:Amgen: Consultancy, Honoraria; Takeda: Honoraria; Janssen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Ocio:Mundipharma: Research Funding; Pharmamar: Consultancy; Amgen: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria; AbbVie: Consultancy; Takeda: Consultancy, Honoraria; Array Pharmaceuticals: Research Funding; Sanofi: Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy; Novartis: Consultancy, Honoraria; BMS: Honoraria. Bladé:Janssen, Celgene, Amgen, Takeda: Membership on an entity's Board of Directors or advisory committees; Irctures: Honoraria. Lahuerta:Takeda, Amgen, Celgene and Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Description: Introduction: The GEM-CESAR trial is a potentially curative strategy for high-risk smoldering multiple myeloma (HRsMM) patients (pts) in which the primary endpoint is the achievement of bone marrow minimal residual disease (MRD) negativity. However, other methods of disease evaluation in serum such as heavy+light chain (HLC) assessment, with a potential complementary value to the IMWG response criteria, have also been tested. Aim: To evaluate the performance of HLC assay in HRsMM pts at diagnosis and after consolidation, comparing the results with standard serological methods and Next Generation Flow (NGF) for the assessment of bone marrow MRD. Patients and Methods: Ninety HRsMM pts included in the GEM-CESAR trial received six 4-weeks cycles of carfilzomib, lenalidomide and dexamethasone followed by high dose melphalan and 2 further cycles of consolidation with the same regimen. All pts received maintenance treatment with lenalidomide for up to 2 years. SPEP and IFE were performed using standard procedures. Serum IgGk, IgGl, IgAk and IgAl HLC concentrations were measured using Hevylite (The Binding Site Group Ltd, Birmingham, UK) on a SPA PLUS turbidimeter. HLC concentrations and ratios were considered abnormal if they were outside the 95% reference ranges provided by the manufacturer. MRD was analyzed by flow cytometry following EuroFlow recommendations (sensitivity, 2x10-6). Standard response assignment was carried out as per the IMWG guidelines. Hevylite responses were assigned and HLC-pair suppression was defined as in Michalet et al (Leukemia 2018). Results: Out of 90 HRsMM pts, 75 had monoclonal intact immunoglobulin and samples available at diagnosis (50 IgG and 25 IgA). HLC ratio was abnormal in 98% of IgG pts and in 100% of IgA pts. Response assessment by Hevylite and standard IMWG criteria were available in 62 pts post-consolidation (Table 1). A good agreement was found between the two methods (kappa quadratic weighting = 0,6327 (0,4016 - 0,8638)). Among 46 pts with assigned CR as per the IMWG response criteria, there were 3 and 8 pts in PR and VGPR according to the Hevylite method, respectively. In 62 cases, paired Hevylite and MRD assessment data were available. Concordant results were found in 72.5% of cases (45/62; HLC+/NGF+ in 15 and HLC-/NGF- in 30 cases) while in the remaining 27.4% of cases results were discordant (17/62; HLC-/NGF+ in 6 and HLC+/NGF- in 11 cases). Post-consolidation, 24, 25.8 and 42.3% of the 62 samples were positive by SPEP, NGF and Hevylite, respectively. HLC-pair suppression was identified in 13/62 pts; 10 had severe HLC-pair suppression at the end of consolidation. After a median follow-up of 32 months (8-128), 93% of pts remain alive and progression-free. Three patients that have already progressed had their responses assessed post-consolidation. The first pt was assigned VGPR by the standard IMWG criteria and PR by Hevylite and was MRD positive by NGF; the second pt was assigned CR by IMWG criteria and Hevylite but had severe HLC-pair immunosuppression and was MRD positive by NGF; the third pt was in CR by IMWG and HLC criteria and was MRD positive by MFC. Conclusions: Moderate agreement was found between response assessment by Hevylite and the standard IMWG methods as well as between Hevylite and MRD assessment by NGF. Most discordances were a result of Hevylite detecting disease in samples negative by the standard methods, but longer follow-up is needed to ascertain its clinical value. HLC assessment could have anticipated the progression noted in 2 (out of 3) patients. Disclosures Puig: Takeda, Amgen: Consultancy, Honoraria; The Binding Site: Honoraria; Janssen: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Paiva:Amgen, Bristol-Myers Squibb, Celgene, Janssen, Merck, Novartis, Roche and Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene, Janssen, Sanofi and Takeda: Consultancy. Rodriguez Otero:Kite Pharma: Consultancy; Celgene Corporation: Consultancy, Honoraria, Speakers Bureau; BMS: Honoraria; Janssen: Consultancy, Honoraria; Takeda: Consultancy. Oriol:Celgene, Amgen, Takeda, Jansse: Consultancy, Speakers Bureau. Rios:Janssen: 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. Alegre:Celgene, Amgen, Janssen, Takeda: Membership on an entity's Board of Directors or advisory committees. de la Rubia:Amgen: Consultancy; Janssen: Consultancy; Celgene: Consultancy; Takeda: Consultancy; AbbVie: Consultancy. De Arriba:Celgene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Takeda: Honoraria. Ocio:Celgene: Consultancy, Honoraria, Research Funding; Sanofi: Research Funding; BMS: Honoraria; Novartis: Consultancy, Honoraria; Array Pharmaceuticals: Research Funding; Pharmamar: Consultancy; Seattle Genetics: Consultancy; Mundipharma: Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria; AbbVie: Consultancy; Janssen: Consultancy, Honoraria. Bladé:Janssen, Celgene, Amgen, Takeda: Membership on an entity's Board of Directors or advisory committees; Irctures: Honoraria. Mateos:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmamar: Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; EDO: Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive: Honoraria; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees.