ALBERT

Description: The impact of cumulative dosing and premature drug discontinuation (PMDD) of bortezomib (V), thalidomide (T), and dexamethasone (D) on overall survival (OS), event-free survival (EFS), time to next therapy, and post-relapse survival in Total Therapy 3 were examined, using time-dependent methodology, relevant to induction, peritransplantation, consolidation, and maintenance phases. Univariately, OS and EFS were longer in case higher doses were used of all agents during induction, consolidation (except T), and maintenance (except V and T). The favorable OS and EFS impact of D induction dosing provided the rationale for examining the expression of glucocorticoid receptor NR3C1, top-tertile levels of which significantly prolonged OS and EFS and rendered outcomes independent of D and T dosing, whereas T and D, but not V, dosing was critical to outcome improvement in the bottom-tertile NR3C1 setting. PMDD of V was an independent highly adverse feature for OS (hazard ratio = 6.44; P 〈 .001), whereas PMDD of both T and D independently imparted shorter time to next therapy. The absence of adverse effects on postrelapse survival of dosing of any VTD components and indeed a benefit from V supports the use up-front of all active agents in a dose-dense and dose-intense fashion, as practiced in Total Therapy 3, toward maximizing myeloma survival.

Description: Total Therapy 2 examined the clinical benefit of adding thalidomide up-front to a tandem transplant regimen for newly diagnosed patients with multiple myeloma. When initially reported with a median follow-up of 42 months, complete response rate and event-free survival were superior among the 323 patients randomized to thalidomide, whereas overall survival was indistinguishable from that of the 345 patients treated on the control arm. With further follow-up currently at a median of 72 months, survival plots segregated 5 years after initiation of therapy in favor of thalidomide (P = .09), reaching statistical significance for the one third of patients exhibiting cytogenetic abnormalities (CAs; P = .02), a well-recognized adverse prognostic feature. The duration of complete remission was also superior in the cohort presenting with CAs such that, at 7 years from onset of complete remission, 45% remained relapse-free as opposed to 20% on the control arm (P = .05). These observations were confirmed when examined by multivariate analysis demonstrating that thalidomide reduced the hazard of death by 41% among patients with CA-positive disease (P = .008). Because two thirds of patients without CAs have remained alive at 7 years, the presently emerging separation in favor of thalidomide may eventually reach statistical significance as well.

Description: Introduction: Despite the enormous progress in MM therapy brought about by the rapid development of many novel agents, many patients end up with limited treatment options. We have previously reported on the efficacy and safety of metro16 in RRMM (Papanikolaou, Haematology 2013). Here we are reporting on an extension of such treatment to 28 d (metro28). Patients and Methods: The treatment consisted of a cycle of 28d continuous iv infusions of ADR and DDP each at 1mg/m2/d, along with thalidomide 50 to 100mg/d x 28; bortezomib 0.8 to 1.0mg/m2 on days 1, 4, 7, 10, 13, 16, 19, 22, 25, 28; DEX 8 to 12mg on days 1-4, 7-10, 13-16, 19-22, 25-28; some patients also received vincristine 0.07mg flat dose by CI for 28 days. This was off-protocol therapy that patients provided written informed consent for. The IRB permitted data retrieval and analysis. Results: 150 patients were identified, virtually all had received prior tandem transplants, bortezomib, lenalidomide, carfilzomib and pomalidomide. The median age was 64yr; B2M was elevated 〉=3.5mg/L in 48%, abnormal cytogenetics (CA) were present in 86%, and 44% had GEP70-defined high risk MM. Figure 1 portrays clinical outcomes. As of April 2015, 60 patients had died, and the 2-yr OS estimate was 45% (Figure 1A); the 6-mo PFS estimate was 31% although 15% had no progression at 18mo (Figure 1B). Analysis by GEP70 and GEP5 risk revealed 18-mo OS estimates of 80% among the 53 patients with low risk in both models, whereas the presence of high risk (HRMM) in either model conferred a significantly reduced 18-mo OS estimate of 25% (p

Description: Abstract 4800 Background: Despite availability of novel agents, many MM patients still relapse and require salvage interventions. In the Arkansas program, we have attempted to procure initially sufficient hematopoietic precursor cells, for use in high-dose therapy salvage regimens once phase I-II trials have been exhausted. We are reporting on the efficacy in terms of response rate, EFS and OS of ARMM patients receiving S-BEAM. Patients and Methods: S-BEAM comprised standard BEAM (carmustine 300 mg/m2 on day 1, etoposide 200 mg/m2 days 1–4, cytarabine 400 mg/m2 days 1–4, melphalan 140 mg/m2 on day 5) with the addition of cisplatin (10-12.5mg/m2/d CI × 5d), bortezomib (1.3-1.5mg/m2 on days 1 + 4), thalidomide (100-200mg/d for 5 days) or lenalidomide (25-100mg/d for 5 days), DEX (40-100mg/d for 5 days) plus rapamycin (3mg d1, 1mg d2-5). Statistical methods included Cox regression modeling using significance level 0.05 and Kaplan-Meier methodology for all figures. Comparisons within figures were made using the log-rank test. Results: The characteristics of 147 patients treated included prior transplant (Tx) in 67% (2Tx, 29%; =〉3Tx, 11%), and prior exposure and resistance in virtually all patients (92%) to bortezomib, thalidomide, lenalidomide applied in VTD, VRD or with chemotherapy VTD-PACE. Pre-S-BEAM high-risk features included low albumin (=3.5mg/L; 32%), high LDH (〉=ULN; 44%), and presence of cytogenetic abnormalities (CA) in 70%. Clinical outcomes included at least PR in 62% including 48% with n-CR and 29% with CR. Two-year estimates of EFS and OS were 29% and 33%; TRM within 60 days was 3%. At 4 years, 23% remain alive and 15% event-free. Independently significant variables affecting both OS and EFS adversely included, in a model without GEP, high B2M (〉5.5mg/L), high LDH (〉=ULN), low hemoglobin (=10 in 42%. When GEP data were included in a subset of 103 patients, high-risk designation, high LDH and age 〉=65 were identified on the basis of highest R2 values (49% for OS, 41% for EFS). Among 28 patients lacking any of these 3 features, 1-year OS/EFS was 83%/67%, with 1 variable (n=36) 53%/38%, with 2 (n=31) 22%/6% and with 3 (n=8) 0%/0% (both P

Description: Introduction Achieving complete remission (CR) improves survival outcomes in multiple myeloma (MM). Applying more sensitive flow-cytometry or PCR based minimal residual disease (MRD) testing further improves prognostication and MRD negativity confers better outcomes among CR patients. In our Total Therapy (TT) trials, gene expression profiling based risk (GEP) identifies 15% patients with high risk (HR) MM whose clinical course is characterized by early relapsing disease and prognosis has remained grim despite advances in therapy. Of interest is whether high-risk (HR) patients fail to achieve MRD negativity leading to relapse. We have determined response rates across the total therapy (TT) trials and in this study we report the impact of molecular negativity by MRD assessment in patients who have achieved at least very good partial response (VGPR) or CR at 4-8 months and 12-24 months, respectively, after enrollment in TT3b-TT5 from 2005-2009. We use next-generation sequencing (NGS)-based MRD assessment (Adaptive Biotechnologies) which is sensitive to 1 MM cell in 106 normal cells. Furthermore, we evaluate MRD status in long term relapse-free survivors (〉6 years) to determine the importance of MRD status in prolonged remission. Materials and methods Study subjects include 591 patients enrolled in TT3b-TT5 to determine VGPR/nCR/CR by EBMT/IMWG criteria and to analyze PFS and OS of HR and SR patients defined by our GEP model. For MRD testing, we identified 102 patients from the TT3b-TT6 protocols that achieved at least VGPR and had bone marrow (BM) sample available at 4-8 months and 12-24 months after enrollment. Of these 102 patients, 14 patients had HR disease and 88 had SR. Six of 14 HR patients already had clinical relapse between 12-24 months, but were included to determine MRD at 4-8 months. Of all 102 patients, 51 are currently still in CR 6-9 years after protocol enrollment and most recent flow-cytometric MRD status was evaluated. NGS-based MRD Assessment: Genomic DNA was amplified using locus-specific primer sets for immunoglobulin heavy-chain complete (IGH-VDJH) and incomplete (IGH-VDH) as well as for immunoglobulin κ locus (IGκ). The amplified products were subjected to sequencing and clonal gene rearrangements were analyzed. Final MRD measurement was calculated at a sensitivity level of 1 cancer cell per 1 million cell equivalents. Flow Cytometry based MRD assessment: Erythrocyte-lysed BM samples were immunophenotyped by use of 8-color (CD138/CD38/CD19/CD45/CD27/CD81/CD56/CD20) staining technique. Myelomatous Plasmacells (PCs) were separated from healthy PCs by different phenotype expression and MRD was deemed negative when no myelomatous PCs were detectable at a sensitivity of

Description: Introduction: Therapy related myelodysplastic syndrome (t-MDS) and acute myeloid leukemia (t-AML) are significant long-term complications of MM treatment. We have treated pts on standard therapy protocols including TT2, TT3, TT4 and TT5. These protocols include an induction, tandem melphalan-based ASCT and consolidation, followed by three years of maintenance. As a part of the protocols, multiple bone marrow examinations including metaphase cytogenetics are performed at regular intervals, giving us the unique opportunity to examine the development of t-MDS/t-AML and understand the efficacy of subsequent treatment. Here we investigate the outcome of t-AML and t-MDS treated with autologous stem cell transplantation (ASCT) in MM patients. Materials and Methods, Results: During the period between 1998 to 2015, a total of 1558 pts were treated for MM with standard therapy protocols. We identified 68 pts out of 1558 who developed t-AML + t-MDS. Thirty-one had a confirmed diagnosis of t-AML, and thirty-seven had a diagnosis of t-MDS. The median age at diagnosis was 60 years (range 45-76). The median time from diagnosis MM of t-AML and t-MDS was 66 months (range, 9.6-155.4) and 63 months (range, 8-130), respectively. Baseline cytogenetics were as follows: complex cytogenetics in 34 pts out of 68, del(7) in 24 pts, del(5) in 17 pts, and del(17p) in 5 pts. Eighteen out of thirty-one t-AML pts were treated with ASCT. The remaining 13 pts did not receive ASCT. The treatment related mortality (TRM) at day100 (D100) in the ASCT group was 33% (6/18 pts). Neutrophil and platelet engraftment was achieved in all 18 pts by D21. Complete remission was achieved in 50% (9 out of 18) of pts. When we compared pts who received ASCT to those who were treated with chemotherapy only, the median overall survival (OS) was 11.28 months after ASCT vs 1.32 months without ASCT (p 〈 0.05). Nineteen out of thirty seven t-MDS pts were treated with ASCT. When we compared pts who received ASCT to chemotherapy only for t-MDS, there was no difference in survival between the groups. A mortality rate of 47% (9/19) was recorded at D200 after transplantation due to severe infections and lack of engraftment. Conclusion: t-AML and t-MDS treatment is a significant therapeutic challenge for the elderly, who often have poor risk cytogenetic markers, significant comorbidities and a compromised performance status. In our case series of post MM therapy t-AML, ASCT prolonged survival. In contrast, there was no change in survival of t-MDS pts, most likely due to high rate of infectious complications seen in this group. To our knowledge, this is the first analysis suggesting a survival benefit from ASCT in treating t-AML. Although the numbers in our study are small, we recommend that ASCT can be safely considered for t-AML patients who are physically fit, have autologous stem cells in storage and are overseen by a good supportive care team. These results need to be validated in large prospective studies. Disclosures Atrash: University of Arkansas for Medical Sciences: Employment. Barlogie:Millennium: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; European School of Haematology- International Conference on Multiple Myeloma: Other: Travel Stipend; ComtecMed- World Congress on Controversies in Hematology: Other: Travel Stipend; International Workshop on Waldenström's Macroglobulinemia: Other: Travel Stipend; Dana Farber Cancer Institute: Other: Travel Stipend; Multiple Myeloma Research Foundation: Other: Travel Stipend; Myeloma Health, LLC: Patents & Royalties: Co-inventor of patents and patent applications related to use of GEP in cancer medicine licensed to Myeloma Health, LLC. Zangari:Onyx: Research Funding; Novartis: Research Funding; Millennium: Research Funding; University of Arkansas for Medical Sciences: Employment. van Rhee:University of Arkansa for Medical Sciences: Employment. Waheed:University of Arkansas for Medical Sciences: Employment. Bailey:University of Arkansas for Medical Sciences: Employment. Petty:University of Arkansas for Medical Sciences: Employment. Heuck:Celgene: Consultancy; Janssen: Other: Advisory Board; Millenium: Other: Advisory Board; Foundation Medicine: Honoraria; University of Arkansas for Medical Sciences: Employment. Morgan:Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; MMRF: Honoraria; Weismann Institute: Honoraria; CancerNet: Honoraria; University of Arkansas for Medical Sciences: Employment; Takeda: 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. Jethava:University of Arkansas for Medical Sciences: Employment.

Description: Abstract 2910 Background: 18-fluorodeoxy-glucose positron emission tomography (18-FDG PET) scanning is increasingly viewed as an important novel imaging tool in the initial workup of multiple myeloma (MM). Recent work from Italian investigators validated our previous report on the prognostic implications of PET scanning in terms of poorer outcome in the presence of higher focal lesion (FL) number, greater FDG uptake intensity, expressed as maximum standardized uptake value (SUVmax) and presence of extramedullary disease. Here, for the first time, we are reporting the prognostic implication of PET-FL and PET-SUVmax suppression after induction chemotherapy as they pertain to survival of patients enrolled in TT3A protocol employing VTD (bortezomib, thalidomide, dexamethasone) and TT3B protocol employing VRD(bortezomib, lenalidomide, dexamethasone), with median follow-up of 78 months and 48 months, respectively. Methods: Imaging parameters included standard metastatic skeletal survey (MBS) delineating the number of osteolytic lesions, STIR-derived MRI-based foal lesion (FL) number (limited to the axial skeleton bone marrow of head, spine, and pelvis). In the absence of FL, diffuse hyper-intense marrow (DHIM) involvement was also annotated1. As for PET scanning, FL number, SUVmax and EMD parameters were captured. PET studies were repeated on day 7 after initiation of the DT-PACE portion of the first induction cycle, prior to first transplant, and prior to maintenance initiation. Imaging data were complete for 429 patients at baseline including 394 with additional information on gene expression profiling (GEP)-derived high-risk. Day-7 PET data were available on 308 and 277 patients, respectively. Cox regression modeling was employed for overall survival (OS), progression free survival (PFS) and complete response duration (CRD). Results: Patient characteristics were fairly comparable among the TT3A and TT3B patients except higher proportions of patients with high-risk features (high beta-2-microglobulin, low albumin, high GEP-derived centrosome index) in TT3B. The number of MBS-OL (〉2) adversely affected OS (p=0.0001) and PFS (p=0.005) in TT3A (p=0.0001), PFS (p=0.03) in TT3B with a trend apparent for OS (p=0.06). For CRD, trends were apparent for shorter CRD in the presence of OL 〉2 in TT3A. In case of baseline PET, results were quite consistent for the 3 endpoints examined and between protocols applied. Thus, patients with 0 or 1–3 FL had equally favorable OS, PFS and, less pronounced in TT3B, CRD. Those with FL 〉3 fared poorly. Adverse consequences of FL-associated SUVmax 〉3.9 are apparent for OS, PFS and CRD in TT3A, whereas with TT3B only trends were apparent. Among follow-up imaging, Day-7 PET was the earliest measure. As is apparent in Figure 1, the presence of more than 3 FL imparted shorter OS and PFS in both TT3A and TT3B, with comparable outcomes noted for patients presenting with 0 or 1–3 FL at that time. Similar trends were apparent for CRD with both TT3A and TT3B. Cox regression modeling that considered additional information on day-7 PET results revealed an independent negative impact of day-7 FL〉3 in the absence and presence of GEP data for both OS and PFS. Importantly, such information made baseline PET-FL irrelevant for OS and PFS, with MBS-OL 〉2 remaining in the model for OS, even when GEP data were also analyzed. The other surviving baseline variables included GEP-70-defined high risk for all 3 endpoints examined including CRD, where no imaging parameter emerged as significant. In the case of day-7 PET-SUV max, prognostic significance only applied to OS and PFS in TT3A. Conclusions: The data presented herein, demonstrate that failure of FDG suppression as early as post-induction chemotherapy carries adverse outcome and can serve as prognostic indicators of long-term survival. We have thus established that early PET follow-up scanning can identify further risk discrimination that can be exploited toward therapy change. Disclosures: No relevant conflicts of interest to declare.

Description: Introduction Gene expression and comprehensive genomic profiling (CGP) underscore the importance of multiple myeloma (MM) being driven by diverse genomic abnormalities and are increasingly being integrated into personalized treatment algorithms to optimize clinical outcomes, in particular that of high risk disease. Furthermore, CGP allow for ultra-deep sequencing of various clinically relevant and targetable genomic alterations using a single assay, with an advantage of detection of low frequency variants. Methods Samples from 578 patients (monoclonal gammopathy of undetermined significance, MGUS, (n=19); smoldering multiple myeloma, SMM, (n=42); or multiple myeloma, MM, (n=517; 87 newly diagnosed (NDMM), 107after treatment (TRMM), and 323 at relapse (RLMM)) were analyzed using the FoundationOne® Heme (F1H) assay. 50 ng of DNA and RNA from CD138+ selected cells were analyzed for genomic alterations including base substitutions, indels, copy number alterations, and rearrangements. Sequencing was performed to a median depth of 468x in 405 genes, as well as selected introns of 31 genes involved in rearrangements. Additionally, matched Gene Expression Profiling (GEP) was performed using Affymetrix U133 Plus 2 array, and GEP70-defined risk status and molecular subgroups were calculated. Results Results of the F1H assay revealed the most common alterations in MM to be: KRAS (28.8%), NRAS (23.2%), TP53 (17.4%), BRAF (6.8%), CDKN2C (6.0%), RB1 (5.8%), TRAF3 (5.8%), DNMT3A (3.9%), TET2 (3.7%) and ATM (2.5%), including mutations, homozygous loss and rearrangements. When these frequencies were split across GEP70 risk groups, TP53, CDKN2C/FAF1, RB1, and the t(4;14) were significantly different (p

Description: Introduction: Next generation sequencing of over 800 newly diagnosed multiple myeloma (NDMM) cases has established the mutational landscape and key cancer driver pathways. The mutational basis of relapse has not been systematically studied. Two previous studies (Keats et al.; Bolli et al.) identified 4 patterns of clonal evolution. Neither study included uniformly treated patients and looked at the impact of therapy on clonal structure at relapse. Understanding the mutational patterns underlying relapse and how they relate to specific therapies is crucial in order to improve MM outcomes, especially for high-risk (HR) MM. In this study we compare the clonal structure at presentation (PRES) and at relapse (REL), after exposure to Total Therapy (TT). Materials and Methods: We studied 33 pairs of tumor samples collected at PRES and REL. 9 patients were treated on TT2, 13 on TT3, 10 on TT4 and 1 on TT5-like regimen. Eleven patients had HR disease at PRES. DNA was extracted from CD138+ selected cells from random bone marrow aspirates. Germline controls were obtained from leukapheresis products. Whole exome sequencing libraries were prepared using the Agilent qXT kit and the Agilent SureSelect Clinical Research Exome kit with additional baits covering the Ig and MYC loci. All samples were sequenced on an Illumina HiSeq2500 to a median depth of 120x. Sequencing data were aligned to the Ensembl GRCh37/hg19 human reference using BWA. Somatic variants were called using MuTect. Translocations were identified using MANTA. Copy number variations were inferred using TITAN. Gene expression profiles (GEP), generated using the Affymetrix U133plus2 microarray, were available for all tumor samples. Nonnegative matrix factorization (NMF) was used to define mutation signatures. Results: The median time to progression was 30 months with a median follow up of 9.5 years. 22 cases achieved a complete remission (CR) or near CR. There were 11 cases of HR at PRES. Of the 22 cases with low risk (LR) MM, 7 relapsed with HR disease. There were on average 478 SNVs per sample at PRES and 422 at REL. All but 2 cases had evidence of new mutations at REL. There were no consistent patterns or number of mutation associated with REL or GEP-defined risk. Patients of the MF molecular subgroup had more mutations compared to other molecular subgroups (657 vs. 379) and were enriched for mutations with an APOBEC signature. We did not detect any mutation signature consistent with chemotherapy-induced alterations, providing evidence that TT itself does not cause additional mutations. Primary recurrent IgH translocations called by MANTA were confirmed by GEP data. A number of new translocations were identified , several only at REL. In particular we demonstrate a case with a newly acquired MYC translocation at relapse, indicating that it contributed to progression. We identified 5 patterns of clonal evolution (Figure 1): A) genetically distinct relapse in 3 patients, B) linear evolution in 8 patients, C) clonal selection in 9 patients, D) branching evolution in 11 patients, and E) stable clone(s) in 2 patients. Patterns A (distinct) and B (linear) were associated with low risk and longer survival, whereas patterns D (branching) and E (stable) were associated with high risk and shorter time to relapse and overall survival (Table 1). Conclusion: This is the first study to systematically analyze the pattern of clonal evolution using NGS in patients treated with combination chemotherapy and tandem ASCT. We identified 5 patterns of evolution, which correlate with survival. We identified 3 cases with a loss of the original clone and emergence of a new clone, suggesting high effectiveness of Total Therapy for those patients. The persistence of major clones despite multi agent chemotherapy in most other cases supports a concept of a tumor-initiating cell population that persist in a protective niche, for which new therapies are needed. Table 1. Pattern of Evolution GEP70 Pres.(high risk: ≥0.66) Proliferation Index Pres. GEP70 Rel.(high risk: ≥0.66) Proliferation Index Rel Mean OS Mean TTR A: distinct (n=3) -0.690 -3.34 -0.015 2.04 8.18 5.00 B: linear (n=8) -0.171 -0.34 0.618 9.22 5.70 4.05 C: selection (n=9) 0.366 3.20 0.569 6.97 3.95 2.64 D: branching (n=11) 0.710 5.17 1.173 11.15 3.84 2.21 E: stable (n=2) 1.532 7.42 1.124 2.54 0.96 0.35 Pres.: Presentation; Rel.: Relapse; OS: Overall Survival; TTR: Time to Relapse Figure 1. Patterns of Relapse Figure 1. Patterns of Relapse Disclosures Heuck: Foundation Medicine: Honoraria; Millenium: Other: Advisory Board; Janssen: Other: Advisory Board; Celgene: Consultancy; University of Arkansas for Medical Sciences: Employment. Weinhold:Janssen Cilag: Other: Advisory Board; University of Arkansas for Medical Sciences: Employment. Peterson:University of Arkansas for Medical Sciences: Employment. Bauer:University of Arkansas for Medical Sciences: Employment. Stein:University of Arkansas for Medical Sciences: Employment. Ashby:University of Arkansas for Medical Sciences: Employment. Chavan:University of Arkansas for Medical Sciences: Employment. Stephens:University of Arkansas for Medical Sciences: Employment. Johann:University of Arkansas for Medical Sciences: Employment. van Rhee:University of Arkansa for Medical Sciences: Employment. Waheed:University of Arkansas for Medical Sciences: Employment. Johnson:University of Arkansas for Medical Sciences: Employment. Zangari:University of Arkansas for Medical Sciences: Employment; Millennium: Research Funding; Onyx: Research Funding; Novartis: Research Funding. Matin:University of Arkansas for Medical Sciences: Employment. Petty:University of Arkansas for Medical Sciences: Employment. Yaccoby:University of Arkansas for Medical Sciences: Employment. Davies:University of Arkansas for Medical Sciences: Employment; Millenium: Consultancy; Janssen: Consultancy; Onyx: Consultancy; Celgene: Consultancy. Epstein:University of Arkansas for Medical Sciences: Employment. Barlogie:University of Arkansas for Medical Sciences: Employment. Morgan:Weismann Institute: Honoraria; MMRF: Honoraria; Bristol Myers Squibb: 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; University of Arkansas for Medical Sciences: Employment; CancerNet: Honoraria; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Description: CS1 is an ideal target for multiple myeloma (MM) therapy as it is highly expressed on MM while having a very limited expression profile in normal tissues.  Elotuzumab (elo), a humanized monoclonal antibody (mAb) targeting CS1, has an acceptable safety profile and clinical activity in relapsed/refractory MM when combined with the immune modulator lenalidomide (len) and low dose dexamethasone (dex).  The primary mechanism of action for elo is NK cell-mediated antibody-dependent cellular cytotoxicity.  Here we report on a patient who was given elo/len via a single patient IND 6 months after receiving therapy with ex vivo activated auto-ENK cells and low dose IL2 as previously described (Szmania et al, Blood ASH Annual Meeting Abstracts 2012;120:1912).  The patient had relapsing GEP70 high-risk MM with cytogenetic abnormalities and had failed multiple lines of prior therapy including 3 auto-PBSC transplants and further salvage treatments including len, bortezomib, pomalidomide and carfilzomib.   Although ENK cell therapy did not induce a response, subsequent disease progression was slow.  IV elo was started 187 days after ENK cell infusion, and given every 14 days at the currently studied dose of 10mg/kg.  Len at 15mg/day was given on days 1-21 of a 28-day cycle.  Dex premedication (p.o. 38mg; IV, 10mg) was added after a grade 2 infusion reaction was observed to elo dose #1. While on the ENK cell protocol this patient had a dramatic increase in circulating NK cell counts peaking 9 days after infusion (6300 NK/µL, a 48-fold increase from baseline). Although still in the high range, NK cell levels at the time of elo treatment had normalized somewhat (539 NK/ml), and the cell surface expression of key activating receptors was consistent with a resting phenotype.  NK cell count remained stable after the first dose of elo (530 NK/ml) but subsequently dipped to 179 NK/µL after elo dose #2.   Since dex has been reported to affect NK cell counts, it is important to note that an additional dose was taken prior to elo dose #2 due to a travel delay (in total 66 mg of dex was taken on this occasion).  Circulating NK cells (collected pre-elo and 11, 25, and 57 days after elo dose #1) had similar low activity against auto-MM collected prior to elo treatment (effector:target ratio 10:1, 0-5% specific lysis) and killing against MM collected after 5 elo doses was only modestly increased (3-12%).  However, the same circulating NK cells exhibited significantly increased cytolytic ability when additional elo (10µg/mL) was added during the in vitro E:T co-incubation (3-11 fold increase in killing over isotype control, p=0.0008) suggesting that the MM targets were not saturated with mAb. Bound mAb may have been reduced in part during target cell isolation and freeze/thaw.  Freshly prepared auto-ENK cells exhibited an activated immunophenotype and induced significantly higher killing of pre-elo MM (45%) compared to non-expanded NK.  ENK killing was higher still against MM collected after 5 doses of elo (61%).  When elo was present during the assay, ENK demonstrated the most effective killing of auto-MM, reaching levels  equivalent to that of the NK sensitive target K562 (85% vs. 82% lysis).  Successful mAb therapy for MM is now moving forward as target antigens with selective, high and homogeneous expression, such as CS1, are identified.  However, the activity of responding effector cells is a critical issue to consider.  Inadequate NK cell count and activity level has been reported in MM and steroids typically given to debulk and preempt mAb-induced infusion reactions may exacerbate this problem.  Immunomodulatory agents given to enhance immune cell activity are not sufficient to reverse the negative effect of steroids.  We have previously shown that large doses of highly activated auto-ENK cells can be safely infused and that these cells expand further after infusion.  In this study we show that ENK cells have significant activity in vitro against auto-MM and that elo further enhances this activity.  Combination therapy incorporating saturating doses of mAb followed by infusion of NK effector cells with optimized activity against auto-MM is an innovative approach that warrants investigation.  Infusing highly activated effector cells after dex/elo may be one way to reap the benefits of combining these modalities while circumventing steroid-induced immune suppression. Disclosures: Barlogie: Celgene: Consultancy, Honoraria, Research Funding; Myeloma Health, LLC: Patents & Royalties.