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Cereblon is the direct binding target of the immunomodulatory drugs (IMiDs) that are commonly used to treat multiple myeloma (MM), the second most frequent hematologic malignancy. Patients respond well to initial treatment with IMiDs, but virtually all patients develop drug resistance over time, and the underlying mechanisms are poorly understood. We identified an as yet undescribed DNA hypermethylation in an active intronic CRBN enhancer. Differential hypermethylation in this region was found to be increased in healthy plasma cells, but was more pronounced in IMiD-refractory MM. Methylation significantly correlated with decreased CRBN expression levels. DNA methyltransferase inhibitor (DNTMi) in vitro experiments induced CRBN enhancer demethylation, and sensitizing effects on lenalidomide treatment were observed in 2 MM cell lines. Thus, we provide first evidence that aberrant CRBN DNA methylation is a novel mechanism of IMiD resistance in MM and may predict IMiD response prior to treatment.

Background: Ruxolitinib is the standard of care for myelofibrosis (MF). However not all patients respond to ruxolitinib and other lose response while on treatment or require discontinuation due to adverse events. Therefore, several clinical trials with ruxolitinib in combination with other drugs are being conducted. We previously showed the synergistic effect of the combination ruxolitinib/nilotinib/prednisone in ex vivo models of peripheral blood mononuclear cells from MF patients and cell lines. Aims: This phase Ib/II study, non-randomized, open-label, evaluates safety and tolerability of ruxolitinib in combination with nilotinib and prednisone in patients with naïve or ruxolitinib-resistant MF. Methods:Between November 2017 and June 2020, 21 patients were included in RUNIC (EudraCT Number:2016-005214-21) at 6 Spanish sites. Six patients were considered screening failures. A total of 15 patients received at least one dose of ruxolitinib and were included in the intention-to-treat (ITT) or the per-protocol (PP) populations. The study design is summarized in figure 1. Out of 15 evaluable patients whose median age was 66.5 years (53.4-70.8). Six patients (40%) had a diagnosis of primary MF, 4 patients (26.7%) post-polycythemia vera MF, and 4 patients (26.7%) post-essential thrombocythemia MF. Most patients had International Prognostic Scoring System (IPSS) intermediate-1 or -2 disease (5 [33.3%] and 4 [26.7%], respectively), and 9 patients (60%) had JAK2 V617F mutation. Most of the patients (n=13; 86.7%) had received ruxolitinib as previous anti-neoplastic therapy for MF. Results:Eight patients completed 7 cycles (53.3%), and six patients 12 cycles (40%) and nine patients withdrawn because of disease progression, lack of efficacy, or no clinical benefit (n=5), withdrawal of consent (n=2), adverse event (AE) (pulmonary thromboembolism, n=1), and investigator's medical judgment (n=1). All patients experienced at least one AE during the study (the most common were hyperglycemia, asthenia and thrombocytopenia, and 14 patients registered at least one treatment-related AE (the most common were hyperglycemia (22.2%), thrombocytopenia (13.3%), and anemia (8.9%)). Five treatment-related serious adverse events (SAEs) were reported in 2 patients (13.3%), all of them related to nilotinib: one patient had pericardial effusion and bilateral pleural effusion, the other had congestive heart failure, pleural effusion, and pulmonary hypertension. No deaths were registered throughout the study.There were 2 patients with at least one adverse event meeting criteria for dose-limiting toxicity: grade 4 anemia and lumbar pain. Only eight patients were evaluated for spleen lengths at screening and cycle 7 (Figure 2B). Of these, 6 experienced a palpable spleen reduction, 4 of them with a 100% reduction. In contrast, one patient remained with the same spleen length, and one patient experienced a 25% increase.Six patients had both symptom evaluation at screening and cycle 7 (Figure 2D). Four experienced a total symptom score reduction, one patient remained with the same total symptom score, and two patients reported an increase.Six patients had spleen length measures recorded both at screening and at cycle 12. From those, 4 showed a spleen length reduction, 3 of them with a 100% reduction. Conclusions: Ruxolitinib in combination with nilotinib and prednisone showed relevant clinical activity in patients with naïve or ruxolitinib-resistant MF. The tolerability of this combination was acceptable, and the hyperglycemia was the treatment-related AE most frequent. The main cause of trial withdrawn was disease progression, lack of efficacy, or no clinical benefit. Based on these results, this triple combination should be explored in phase II/III clinical trials. Figure 1 Figure 1. Disclosures Ayala: Incyte Corporation: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astellas: Honoraria; Celgene: Honoraria. Garcia Gutierrez: BMS: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Incyte: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding. Osorio: Janssen, Abbvie, Roche: Consultancy. Sanchez: Janssen, Jazz Pharmaceuticals, Gilead, Novartis, Amgen: Consultancy. Martínez-López: Janssen, BMS, Novartis, Incyte, Roche, GSK, Pfizer: Consultancy; Roche, Novartis, Incyte, Astellas, BMS: Research Funding.

Background: Heavily pretreated relapsed and refractory multiple myeloma (RR MM) constitutes a specific and unmet medical need. Median survival ranges from as little as 6 to 9 months, and responses to treatment are characteristically short (Richardson et al. 2007). Belantamab Mafodotin (BM), a novel anti-BCMA antibody conjugated to microtubule-disrupting agent monomethyl auristatin F, showed single-agent activity in the phase 1 DREAMM-1 and phase 2 DREAMM-2 studies in heavily pre-treated patients with RRMM (Lonial et al, 2019 & 2021). We aim to assess efficacy and safety of BM treatment administered via the expanded access compassionate care program for triple class MMRR patients in the region of Madrid (Spain). Methods: An observational, retrospective and multicenter study has been performed including all patients who received at least one dose of BM under the expanded access program in the region of Madrid (Spain) from Nov 2019 to Jun 2021. Hematology centers provided data from the medical records and entered them in a case report form distributed to the sites. Primary endpoint was overall response rate (ORR). Secondary endpoints were progression free survival (PFS), overall survival (OS) and the incidence of treatment emergent adverse events (TEAEs), with a major focus on ocular and hematologic toxicity. Results: A total of 33 patients (pts), from 14 different centers, were included from February 2020 till May 2021. Median age was 70 (46-79) years. 55% of the pts were women. Median time from diagnosis was 71 (10-858) months. 30.3% were high-risk cytogenetic features. Median of prior therapy lines was 5 (3-8) and at least 88% of the pts were triple class refractory. The median number of BM doses per patient was 3 (1-16) and the median follow-up was 11 months (95%CI 6.34-15.66). ORR was 42.2%, and 18.2% achieved ≥VGPR. Median PFS was 3 months (95%CI 0.92-5.08). Median PFS for patients who achieved ≥PR was 11 months (HR 0,26; 95% CI 0,10-0,68). No significant differences were found in PFS according to age, cytogenetic risk and prior therapy lines. OS was 424 days (95% CI 107-740). The incidence of non-hematological TEAEs was 57.6% and the most common of which was ocular toxicity (45.5%). The incidence of ≥G3 non-hematological TEAEs was 30.3%. 51.5% of the pts were diagnosed of keratopathy and 21.2% was ≥G3. 30.3% of the pts showed a reduced visual acuity, but this event was resolved in 92.9% of the pts. The most common symptoms were blurry vision (30.3%, n=10) and dry eye (24.2%, n=8). The incidence of ≥G3 hematological TEAEs was 18.2% and thrombocytopenia was the most frequent (21.2%). Dose reductions of BM were required in 30.3% of the pts and delayed in 36.4% due to TEAEs. Main causes for treatment discontinuation (81%, n=27) were disease progression (54.5%, n=18), toxicity (15.2%, n=5), death (6.1%, n=3) and due to patient's decision (3%, n=1). Conclusion: Compassionate use of BM in heavily pretreated RR MM pts showed a relevant anti-myeloma activity with a manageable safety profile.These results are similar to those observed in the DREAMM-1 and DREAMM-2 clinical trials. Disclosures No relevant conflicts of interest to declare.

Background Measurable residual disease (MRD) testing in multiple myeloma (MM) is increasingly being utilized in clinical trials for the assessment of disease response and as a prognostic tool for predicting response duration. However, there is only limited evidence to date for the use of MRD to make clinical decisions, a serious barrier to its potentially important role in the management of MM patients. This retrospective review analyzes the results of making clinical decisions to change therapy based on MRD assessments in MM patients. Methods We reviewed 373 patients with MM from 3 health centers through a retrospective search. Patients included in the study had at least one MRD assessment. Clinical decisions to change therapy based on MRD were made in 3 directions: 1. Stop or reduce treatment after MRD negative results; 2. Increase intensity of treatment after MRD positive results; 3. Start a new treatment line after MRD positive results. We gathered all the available data on clinical and biological parameters, induction treatment and response monitoring. MRD was assessed by flow cytometry or next-generation sequencing (Clonoseq) with sensitivity from 10-5to 10-6Statistical analyses were performed with SPSS software version 21.0 (SPSS, Inc., IBM, Armonk, NY). Results In 58 out of 373 (16%) patients a clinical decision to change therapy was made. Treatment was reduced or stopped in 24 cases (group 1). Intensity of treatment was increased in 20 cases(group 2) and a new treatment was started in 13cases(group 3). Most of these decisions were implemented during the post-ASCT maintenancephase, although in 3 cases ASCT was avoided based on the MRD result. For all 373 patients, the median progression-free survival (PFS) was 80 months. Of the 58 cases where a clinical decision was made to change therapy, 33 cases were MRD positive and 25 were MRD negative at the time the decisions were made. 33 patients in this group either remained MRD negative or eventually achieved MRD negativity. Patients in which a clinical decision was made to change therapy based on MRD (n=58) had a prolonged progression free survival versus those in which therapy remained the same (n=312) (median PFS 97 vs. 75 months, p=0.006) (Figure 1). Moreover, we once again confirmed that patients who achieve MRD negativity demonstrate a prolonged PFS vs those who don't achieve negativity (median PFS 97 vs. 57 months, p=0.0001). Conclusion Clinical decision-making to change therapy based on MRD in MM patients can improve patient outcomes. These results support the integration of MRD assessment in the management of MM patients. Disclosures Wong: Fortis: Research Funding; GSK: Research Funding; Roche: Research Funding; Janssen: Research Funding; Amgen: Consultancy; Sanofi: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Research Funding. Shah:GSK, Amgen, Indapta Therapeutics, Sanofi, BMS, CareDx, Kite, Karyopharm: Consultancy; BMS, Janssen, Bluebird Bio, Sutro Biopharma, Teneobio, Poseida, Nektar: Research Funding. Barrio Garcia:Altum sequencing: Current Employment. Martin:GSK: Consultancy; Sanofi: Research Funding; AMGEN: Research Funding; Seattle Genetics: Research Funding; Janssen: Research Funding. Wolf:Adaptive: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

High protein load is a feature of multiple myeloma (MM), making the disease exquisitely sensitive to proteasome inhibitor (PIs). Despite the success of PIs in improving patient outcome, the majority of patients develop resistance leading to progressive disease; thus, the need to investigate the mechanisms driving the drug sensitivity vs resistance. With the well-recognized chaperone function of 14-3-3 proteins, we evaluated their role in affecting proteasome activity and sensitivity to PIs by correlating expression of individual 14-3-3 gene and their sensitivity to PIs (bortezomib and carfilzomib) across a large panel of MM cell lines. We observed a significant positive correlation between 14-3-3ε expression and PI response in addition to a role for 14-3-3ε in promoting translation initiation and protein synthesis in MM cells through binding and inhibition of the TSC1/TSC2 complex, as well as directly interacting with and promoting phosphorylation of mTORC1. 14-3-3ε depletion caused up to a 50% reduction in protein synthesis, including a decrease in the intracellular abundance and secretion of the light chains in MM cells, whereas 14-3-3ε overexpression or addback in knockout cells resulted in a marked upregulation of protein synthesis and protein load. Importantly, the correlation among 14-3-3ε expression, PI sensitivity, and protein load was observed in primary MM cells from 2 independent data sets, and its lower expression was associated with poor outcome in patients with MM receiving a bortezomib-based therapy. Altogether, these observations suggest that 14-3-3ε is a predictor of clinical outcome and may serve as a potential target to modulate PI sensitivity in MM.

Despite advances and improvements in survival, majority of multiple myeloma (MM) patients ultimately relapses. Extensive analysis on the properties of tumor cells has provided interesting insights into the disease biology allowing for the identification of novel targets and development of related therapeutics. However, the key microenvironmental influences, especially immune microenvironment, that drive the disease and impact outcome remain to be fully characterized. We have now performed both single cell RNA-sequencing and high-dimensional CyTOF analysis of both peripheral blood (PBMC) and bone marrow mononuclear cells (BMMC) from MM patients and healthy donors (HD) and evaluated both phenotypic and functional state of the MM immune repertoire. In addition to humoral immunodeficiency impacting aberrations in B-cell subsets (B1a, B1b, B2 and Breg cells) and the disfunction in the adaptive immune system including an increase in the immunosuppressive cells (Tregs or myeloid-derived suppressor cells), a significant impairment of the innate immunity was identified in MM patients with a progressive decline in functional state of natural killer (NK) cells. Additionally, a lower expression of the activating receptors NKG2D and NKp46 as opposed to a higher expression of certain inhibitory KIR receptors was observed in NK cells from MM patients compared to HD. This immunosuppressive microenvironment allows tumor immune escape and ultimately myeloma cell growth. To overcome some of the immune dysfunction observed in MM, we have evaluated the role of IL15, a key player in both innate and adaptive immunity, with antitumor activity via enhancing both NK and memory T cell functions. Using extensive flow cytometry-based analysis, we evaluated impact of recombinant IL15 on PBMC from HD and MM patients at different stages of disease. Treatment with recombinant IL15 rescued the immune effector cell decline observed in MM patients. Specifically, a 2.9-fold-increase in CD8+ CD45RO+ CCR7- effector memory T cells and a 1.5-fold-increase in NK populations in both HD and MM PBMC was observed. For a subset of MM patients, we have also confirmed these positive effects on BMMC. Importantly, cytotoxicity tests revealed an improvement in NK cell effector functions leading to increased tumor cell recognition and killing, while we did not observe any direct effect of IL15 on growth and viability of MM cells. Integration of IL15 in the immunotherapeutic arsenal is limited by the unfavorable pharmacokinetic properties. Therefore, for clinical application and to restore both innate and adaptive immunity, we evaluated impact of NKTR-255, a polymer-conjugated IL15 receptor agonist designed to engage the IL-15 pathway to stimulate and expand natural killer (NK) cells and promote the survival and expansion of central memory CD8+ T cells without inducing suppressive regulatory T cells. Treatment with NKTR-255 enhanced the number and function of both NK and CD8+ effector memory T cell populations in PBMC from HD and MM patients in a dose dependent manner. Interestingly, the natural killer T (NKT) cells, heterogeneous group of T cells that share properties of both T cells and NK cells with important role in MM, were also increased in number by NKTR-255. To evaluate if NKTR-255 increases NK recognition of MM cells, cytotoxicity tests were performed using several MM cell lines and primary MM cells as targets, and both NK cells purified from PBMC of HD and MM patients as effectors. NKTR-255 was able to revert the inhibitory status of NK cells from MM patients (via induction of NKG2D expression), and significantly increase NK susceptibility of the MM cells in a dose dependent manner. Taken together, our data suggest a significant impact of NKTR-255 on the activation of effector cell function to efficiently target MM cells. This study has important translational implications and highlights the importance of restoring the balance between innate and adaptive immunity in MM. Disclosures Miyazaki: Nektar Therapeutics: Employment, Equity Ownership. Madakamutil:Nektar Therapeutics: Employment, Equity Ownership. Munshi:Amgen: Consultancy; Celgene: Consultancy; Abbvie: Consultancy; Adaptive: Consultancy; Janssen: Consultancy; Takeda: Consultancy; Oncopep: Consultancy.

INTRODUCTION: Recently, new understanding of monoclonal gammopathy pathogenesis highlighted possible disease initiation by viral infection in subsets of patients, notably by hepatitis C virus (HCV). If the infectious pathogen targeted by the monoclonal Ig could be eliminated at the monoclonal gammopathy of undetermined significance (MGUS) stage, chronic antigen-stimulation could disappear, leading in turn to the disappearance of the monoclonal Ig. Here we report a series of patients with monoclonal gammopathy and HCV infection, whose disease prognosis clearly improved, even reached complete remission, after antiviral treatment. METHODS: Nine patients diagnosed with MGUS (n=6) or multiple myeloma (MM) (n=3) after HCV infection were included in the study and classified into two groups: patients who received antiviral treatment, and patients who did not receive anti-viral treatment. Disease status was monitored by the quantification of the monoclonal immunoglobulin (mc Ig) level. The HCV burden was determined by RT-qPCR. Each patient's mc Ig was isolated from polyclonal immunoglobulins by agarose gel electrophoresis and mc Ig purity was evaluated by isoelectric focusing. The multiplex infectious antigen microarray (MIAA) was used to analyze the reactivity of serum immunoglobulins and of monoclonal Ig against commercially available antigens and/or lysates from different microorganisms. The INNO-LIA™ HCV Score assay (Fujirebio) was used to analyze the reactivity of monoclonal Ig to HCV proteins. RESULTS: Regarding patients treated with antiviral drugs (4 MGUS, 2 MM), mc Ig levels in serum decreased after antiviral treatment. MGUS patients remained in a stable status without disease progression. After antiviral treatment, one MM patient who was in third relapse achieved complete remission with minimal residual disease negativity. As expected, the HCV load decreased after antiviral therapy to undetectable levels. Serum samples from patients were reactive against antigens of various viruses and other microorganisms, but analysis of the specificity of recognition of the purified mc Ig of each patient revealed that it targeted HCV, either the core protein (C1, C2), NS3, or NS4. In contrast, for patients who did not receive antiviral treatment (2 MGUS, 1 MM), MGUS and MM disease progressed and the mc Ig level remained stable or increased. Serum samples from these patients were reactive against various viruses and other microorganisms, but their mc Ig did not recognize HCV proteins. CONCLUSION: In this study of monoclonal gammopathies where the mc Ig targeted HCV, successful HCV eradication with antivirals resulted in improvement of MGUS and MM disease as well as of hepatitis C. Our findings suggest that for HCV-positive individuals who were infected before being diagnosed with MGUS or MM, a causal relationship exists between HCV infection and the development of MGUS and MM, and both MGUS and MM patients infected with HCV may benefit from early anti-HCV therapy. Disclosures No relevant conflicts of interest to declare.

Introduction: To discriminate different outcomes among patients in CR, the International Myeloma Working Group (IMWG )introduced more stringent CR (sCR) criteria by adding to the pre-existing CR parameters the requirement of a normal free-light chain ratio (sFLCr) plus the absence of clonal plasma cells (PCs) in bone marrow (BM) by immunohistochemistry (IHC). In 2011,the low-sensitivity cytometrycriteria were included as alternative methodology to IHC to define sCR. Aim: To validate the preliminary data of our previous study (Blood 2015. 126:858-62) regarding the lack of influence of an abnormal sFLCr in the outcome of MM patients, through the analysis of a more extensiveseries of newly diagnosed multiple myeloma (NDMM) patients in CR or sCR. Patients and Methods: This study is based on 459 NDMM patients who were transplant candidates and enrolled in the GEM2012MENOS65phase 3trial;evaluable patients were enrolled in a subsequent maintenance trial (NCT02406144).CR and sCR was defined according to the IMWG criteria. Agreeing to the protocol, patients with 1.65 if the patient was κ). BM aspirates were assessed for morphological enumeration of PCs and monitoring of minimal residual disease (MRD) using next-generation flow (NGF) according toEuroFlow SOPs. The median limit of detection was of 3x10-6. We classified as sCR all patients in CR with normal sFLCr and absence of clonal PCs by NGF with a reduced threshold of sensitivity to 10-4.The median follow-up was 40 months. Results: After ASCT,392 patients were evaluable for response; 239 (61%) reached ≥CR. Data from sFLCr and MRD was available in 225 and 221 patients, respectively. In 153 out of a total of 203 (74%) patients in CR in which complete information about FLC and MRD was available were categorized as sCR. The remaining 55 patients were consider in CR because of failure to accomplish 1 of the 2 criteria: abnormal sFLCr (n=49) or MRD+veby low sensitivity flow (n=11); 5patientsshared both criteria.In a landmark from ASCT, with a follow up of 27 months, sCRdidn't show significantly differences inPFS (2 years-PFS 90% vs 83%; P=.2) neither in OS (2 years-OS 96% vs 98%; P=.6) as compared to CR patients.Interestingly, patients with abnormal (n=51) vs normal (n=174) sFLCr showed superimposable PFS (2 years-PFS 86% vs 88%; P=.6) and OS (2 years-OS 95% vs 100%; P=.2).By contrast, in the 11 patients (out of the 221, 5%) with persistent MRD (>10-4) the PFS was significantly poorer as compared with MRD-ve cases (2-yearsPFS 91% vs48%; P=.001)but the OS was similar (2 years-OS 98% vs 96%; P=.3).As validation, we reproduced the analysis in the consolidation-2 end-point (figure 1), where375patients were evaluable for response assessment,267 of them (71%) reached ≥CR. Once again, in the landmark analysis, sCR didn't show significantly differences in PFS with respect to CR patients (2 years-PFS 88% vs 84%; P=.2) neither in OS (2 years-PFS 96% vs 90%; P=.3); moreover, patients with abnormal (n=55) vs normal (n=195) sFLCr showed superimposable PFS (2 years-PFS 84% vs 87%; P=.4) and OS (2 years-OS 89% vs 96%; P=.2).In the MRD analysis, patients with persistent MRD, had significantly inferior PFS (2-years PFS 87% vs 72%; P=.04 for >10-4 MRDsensitivity). If we increase the sensitivity of the MRD to 10-6, the differences in PFS at 2 years are more evident (2 years-PFS 94% vs 67%; P10-6 sensitivity). Conclusion: These results confirm our previous findings based on GEM05menos65/ GEM10mas65 clinical trials, indicating that for MM patients stringent CR criteria does not predict a different outcome as compared to standard CR. Specifically, the sFLCr doesn't identify patients in CR at distinct risk. If this essential criterion in the definition of sCR lacks connotations for the prognosis, is it not justified to maintain a response category whose real significance depends on the combination of the traditional CR criteria with a negative MRD status based on very low (IHC) or low resolution ( Figure 1. Figure 1. Disclosures Martinez Lopez: Janssen: Research Funding, Speakers Bureau; Bristol Myers Squibb: Research Funding, Speakers Bureau; Novartis: Research Funding, Speakers Bureau; Celgene: Research Funding, Speakers Bureau. Rosinol:Janssen, Celgene, Amgen, Takeda: Honoraria. Puig:Takeda: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Research Funding; Celgene: Honoraria, Research Funding. Oriol:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: 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. Ocio:Pharmamar: Consultancy; AbbVie: Consultancy; Seattle Genetics: Consultancy; BMS: Consultancy; Janssen: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Sanofi: Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Mundipharma: Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Array Pharmaceuticals: Research Funding. De La Rubia:Ablynx: Consultancy, Other: Member of Advisory Board. Rios:Amgen, Celgene, Janssen, and Takeda: Consultancy. Mateos:Janssen: 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; GSK: 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; Celgene: Consultancy, Honoraria, 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. San-Miguel:Sanofi: Consultancy; Takeda: Consultancy; Novartis: Consultancy; MSD: Consultancy; Janssen: Consultancy; Celgene: Consultancy; Brystol-Myers Squibb: Consultancy; Amgen: Consultancy; Roche: Membership on an entity's Board of Directors or advisory committees. Bladé:Amgen: Honoraria; Celgene: 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.

* A.R. and M.L. have contributed equally. INTRODUCTION: Despite great advances in knowledge and treatment in the last decade, multiple myeloma (MM) remains an incurable disease. Several studies suggest its association with infectious pathogens, such as hepatitis C virus (HCV) and Epstein Barr virus (EBV). Here we report on the case of a female MM patient in fourth relapse (after VTD treatment + ASCT+ Lenalodomide maintenance and experimental NK therapy + Lenalidomide and lastly Bendamustine), who achieved stable complete response (CR) once her HCV infection was successfully treated, thus establishing a probable relationship between HCV infection and MM in this patient. METHODS: Serum samples from the patient were analyzed before and after antiviral treatment (Sofusbuvir + Ledipasvir). The HCV burden was determined by RT-qPCR. Additionally, viral loads of EBV and Cytomegalovirus were established by qPCR.The number of tumor plasma clones was determined in bone marrow samples by NGS using the Ion Proton sequencer and a depth of 2000 readings/nucleotide. Monoclonal immunoglobulins (mc Ig) were separated from polyclonal Ig by agarose gel electrophoresis and elution. Mc Ig purity was evaluated by isoelectric focusing and immunodetection with anti-IgG antibodies. Their reactivity to different microbial antigens was determined by means of the multiplex infectious-antigen microarray (MIAA) assay and using the commercial kit INNO-LIA HCV score (Fujirebio). RESULTS: The patient, age 66, presented with ISS IIA stage MM (56.7 g/L mc IgG, 2.7 g/L free lambda chains, 2.9 mg/L b2-microglobulin, 90% plasma cells in the bone marrow, without genetic alterations, and osteolytic lesions). HCV infection, causing hepatic toxicity, was discovered in this patient before MM disease. The patient was in third relapse of MM treatment when she received anti-HCV treatment. After antiviral therapy, the HCV load in the patient's serum decreased to undetectable levels (Fig. 1a). Simultaneously, the patient achieved CR of MM, with minimal residual disease (MRD) negativity, as assessed by multiparameter flow cytometry (MFC). NGS revealed the existence of at least one plasmacytic clone, which became MRD negative after anti-HCV treatment (Fig. 1b). Before and after anti-HCV treatment, the patient's serum samples were reactive against antigens of various viruses and other microorganisms (Fig. 1c). Agarose gel electrophoresis of pre-HCV treatment samples showed one band of mc IgG, which disappeared after anti-HCV treatment (Fig. 1d). The patient's mc IgG was purified (Fig. 1e) and analysis of its specificity of recognition revealed that it targeted the HCV core protein (Fig. 1f). Three years have now passed after HCV treatment, and the patient remains in stable CR of MM. CONCLUSION: In this case of refractory MM where the patient's mc IgG targeted HCV, successful HCV eradication with antivirals Sofosbuvir and Ledipasvir resulted in persistent complete remission of MM as well as of hepatitis C. These results suggest that for HCV-positive individuals, a causal relationship exists between HCV infection and the development of MM, and that MM patients infected with HCV would benefit from early anti-HCV therapy. Disclosures Martinez Lopez: Celgene: Research Funding, Speakers Bureau; BMS: Research Funding, Speakers Bureau; Jansen: Research Funding, Speakers Bureau; Novartis: Research Funding, Speakers Bureau.

Background FLT3, PIM1, PIM2 and CXCR4 are proteins implicated in the signal transduction of the regulation of proliferation, differentiation and survival of hematopoietic stem cells, at different levels. The impairing of these three processes, regulated by these molecules, constitutes the main hallmark of Acute Myeloid Leukemia (AML). The objectives of this work were to evaluate the expression level of the genes that codify such proteins in patients with AML; as well as correlate this level of expression with biological variables at diagnosis and survival. Methods peripheral blood or bone marrow samples from 31 healthy subject (HS) and 92 AML patients at diagnosis between 2004 and 2012 were studied. The median follow up was 14 months (69% of patients had died). We quantified the expression of FLT3, PIM1 and 2, and CXCR4 by real time PCR, employing primer pairs designed in our laboratory to amplify all known protein-coding transcripts; highlighting the presence of a 30.4% FLT3 ITD, 5.4% of other FLT3 mutations and 26% of NMP1 mutations. Results were then analyzed with the statistical package IBM“ SPSS” Statistics, v20 (IBM“, Nueva York). Results FLT3 was overexpressed in AML patients (FLT3 expression: controls 0.99 vs patients 36.97; p We observed a higher expression of PIM2 in secondary AML (PIM2 35.17 vs. 17.8; p=0.01) and lower PIM2 expression in the intermediate genetic risk group (low risk 25.51, intermediate risk 14.7 and high risk 33.28; p=0.015). CXCR4 had lower expression in the intermediate cytogenetic risk group (low risk 113.31, intermediate risk 65.2, high risk 146.94; p=0.041) (Table 2). No differences in gene expression were noted in relation to chemotherapy response level. We studied differences in gene expression between granulocytes and blast cells from 19 samples, finding a marked tendency to higher FLT3 expression (FLT3 blasts 35.26 vs FLT3 granulocytes 17.98; p=0.062) and lower PIM1 (PIM1 blasts 69.14 vs PIM1 granulocytes 206.88; p=0.130), PIM2 (PIM2 blasts 26.25 vs PIM2 granulocytes 107.39; p=0.182) and CXCR4 (CXCR4 blasts 188.96 vs CXCR4 granulocytes 420.28; p=0.186) expression in blast cells. The gene expression was clearly different, but not statistically significant, probably due to the limited number of samples studied. Gene expression variable was categorized as high expression above median and low expression below median. High expression of FLT3 was associated with a tendency to reach higher survival (p=0.146). Patients with CXCR4 low expression level had a lower survival (p= 0.045) (Fig.1). Also PIM2 overexpression –defined as a expression level over 75 percentile- was associated with a slightly lower survival. Summary/Conclusion The deregulated expression of FLT3, PIM1, PIM2 and CXCR4 relates to differential characteristics of certain AML groups and has prognostic implications. It is noteworthy that CXCR4 overexpression seems to be associated with higher survival in AML patients. All these results must be confirmed with future studies including a greater number of samples. Disclosures: No relevant conflicts of interest to declare.

Background Acute lymphoblastic leukemia (ALL) is a heterogeneous disease comprising different genetic abnormalities. An increased cytokine receptor-like factor 2 (CRLF2) expression is associated with activating the JAK-STAT pathway and activation and leukemia initiation. Several studies have shown that some first events are insufficient to cause the development of ALL and other genetic changes are required. In 60% of cases, the altered genes are involved in lymphoid maturation (PAX, IKZF1, EBF, LEF1, BTALA/CD200, TOX), cell cycle control and tumour suppression (CDKN2A/B, PTEN, RB), or transcription factors and coactivators (ETV6, ERG, TBL1XR1). But the prognostic significance of deregulated CRLF2 mRNA expression in patients with CNA in the genes previously mentioned is not fully identified. Aims To analyze the frequency and prognostic significance of deregulated expression of CRLF2 and the copy number alterations (CNA) in EBFF1, IKZF1, JAK2, CDKN, PAX, ETV, BTG1 and RB in a series of ALL patients enrolled in BFM, SHOP or PETHEMA clinical trials. Methods Bone Marrow samples at diagnosis from 69 ALL patients treated in Hospital Universitario 12 de Octubre, between January 2001 and December 2012, were studied by Multiplex ligation- dependent probe amplifications (MLPA) method was used to detect deletions or duplications of IKZF1, PAX5, ETV6, RB1, BTG1, EBF1 and CDKN2A-CDKN2B genes (SALSA MLPA kit P335-B1 ALL-IKZF1; MRC- Holland). Raw data was analyzed using Coffalyzer software (MRC-Holland) Results The median age was 22 years (0.9-88), 40 (58%) male and 29 (42%) female, median WBC count 70,753 x109/L (1,000 – 633,780). B-ALL subtype in 64 cases (92%) and T-ALL subtype in 5 cases (8%). Cytogenetics: 10 normal (14.5%), 16 hyperdiploid (20,5%), 8 t(9;22)(10.3%),4 cases 11q23/MLL (5.1%), and 24 (30.8%) with other translocations or deletions and no growth (23.1%). Cytogenetics risk was favourable in 25 cases (26.6%), intermediate in 10 cases (10.6%) and poor in 25 cases (26.6%). CRLF2 expression and CAN results are shown in table 1. CRFL2 over expression was found in 18 cases (23%), it was associated with deletions of IKZF1 (p0.013). Deletions of CDNK were associated with T-ALL subtype (p0.049) and with a tendency to deletions TEL group (p0.081). Deletions of PAX were associated with JAK2 deletions (p0.027) and with a tendency to IKZF1 deletions (p0.064). Rb deletions were associated with ph+ ALL (p0.001) and it had a tendency to the risk of death. Other molecular alterations found were gains of gen EBF 2 (2.6%), IKZF 2 (2.6%), CDKN 4 (5.1%), PAX 5(6.4%), BTG 2 (2.6%), RB 2 (2.6%). There was no association between hyperdiploid karyotype and any of the gene gains analyzed. Regarding survival, CDKN deletions 2A/ B were associated with decreasing of progression free survival P (0.051), independent of the presence of Ph chromosome. Deletions of IKZF1 showed an increased risk of death (p0.011) and tendency for deletions of PAX (p0.064). Conclusions Our findings are consistent with those of other published series. CDKN deletions 2A / B were associated with a decreased progression free survival, independent of the presence of Ph chromosome as described in other series. RB deletions are associated with ph + and have not been described previously, but these findings must be confirm with additional studies. Disclosures: No relevant conflicts of interest to declare.