Myeloma Response Research Articles

Co-evolution of Immune Response in Multiple Myeloma: Implications for Immune Prevention.

Multiple myeloma (MM), a malignant neoplasm of plasma cells that reside in the bone marrow (BM), is universally preceded by a precursor state termed monoclonal gammopathy of undetermined significance (MGUS). Many individuals with MGUS never progress to MM or progress over many years. Therefore, MGUS provides a unique opportunity to surveil changes in the BM tumor microenvironment throughout disease progression. It is increasingly appreciated that MGUS cells carry many of the genetic changes found in MM. Prior studies have also shown that MGUS cells can be recognized by the immune system, leading to early changes in the BM immune environment compared to that of healthy individuals, including alterations in both innate and adaptive immunity. Progression to clinical MM is associated with attrition of T cells with stem memory-like features and instead accumulation of T cells with more terminally differentiated features. Recent clinical studies have suggested that early application of immune-modulatory drugs, which are known to activate both innate and adaptive immunity, can delay the progression to clinical MM. Understanding the biology of how the immune response and tumors coevolve over time is needed to develop novel immune-based approaches to achieve durable and effective prevention of clinical malignancy.

Biallelic loss of BCMA as a resistance mechanism to CAR T cell therapy in a patient with multiple myeloma

BCMA targeting chimeric antigen receptor (CAR) T cell therapy has shown deep and durable responses in multiple myeloma. However, relapse following therapy is frequently observed, and mechanisms of resistance remain ill-defined. Here, we perform single cell genomic characterization of longitudinal samples from a patient who relapsed after initial CAR T cell treatment with lack of response to retreatment. We report selection, following initial CAR T cell infusion, of a clone with biallelic loss of BCMA acquired by deletion of one allele and a mutation that creates an early stop codon on the second allele. This loss leads to lack of CAR T cell proliferation following the second infusion and is reflected by lack of soluble BCMA in patient serum. Our analysis suggests the need for careful detection of BCMA gene alterations in multiple myeloma cells from relapse following CAR T cell therapy.

DNA Damage Response in Multiple Myeloma: The Role of the Tumor Microenvironment.

Simple SummaryMultiple myeloma (MM) is a plasma cell malignancy. Novel therapies have improved outcomes in MM patients; however, MM still remains incurable. MM cells present genomic instability, whose molecular basis is not fully understood. Recently, it has been reported that the DNA damage response (DDR) may influence genomic changes and drug resistance in MM. An abnormal DNA repair function may provide an alternative explanation for genomic instability. In this review, we show an overview of the DNA repair pathways and discuss the role of the tumor microenvironment in governing the DNA repair mechanisms. The tumor microenvironment factors, such as hypoxia and inflammation, and chemotherapeutic agents profoundly influence the DNA repair pathways in MM.Multiple myeloma (MM) is an incurable plasma cell malignancy characterized by genomic instability. MM cells present various forms of genetic instability, including chromosomal instability, microsatellite instability, and base-pair alterations, as well as changes in chromosome number. The tumor microenvironment and an abnormal DNA repair function affect genetic instability in this disease. In addition, states of the tumor microenvironment itself, such as inflammation and hypoxia, influence the DNA damage response, which includes DNA repair mechanisms, cell cycle checkpoints, and apoptotic pathways. Unrepaired DNA damage in tumor cells has been shown to exacerbate genomic instability and aberrant features that enable MM progression and drug resistance. This review provides an overview of the DNA repair pathways, with a special focus on their function in MM, and discusses the role of the tumor microenvironment in governing DNA repair mechanisms.

Treatment of Multiple Myeloma Using Chimeric Antigen Receptor T Cells with Dual Specificity.

Chimeric antigen receptor (CAR) T-cell therapy has shown remarkable successes in fighting B-cell leukemias/lymphomas. Promising response rates are reported in patients treated with B-cell maturation antigen (BCMA) CAR T cells for multiple myeloma. However, responses appear to be nondurable, highlighting the need to expand the repertoire of multiple myeloma-specific targets for immunotherapy and to generate new CAR T cells. Here, we developed a "dual-CAR" targeting two multiple myeloma-associated antigens and explored its safety and efficacy. To reduce the "off-target" toxicity, we used the recognition of paired antigens that were coexpressed by the tumor to induce efficient CAR T-cell activation. The dual-CAR construct presented here was carefully designed to target the multiple myeloma-associated antigens, taking into consideration the distribution of both antigens on normal human tissues. Our results showed that the CD138/CD38-targeted dual CAR (dCAR138-38) elicited a potent anti-multiple myeloma response both in vitro and in vivo NSG mice transplanted with a multiple myeloma cell line and treated with dCAR138-38 showed median survival of 97 days compared with 31 days in the control group treated with mock-lymphocytes. The dCAR138-38 showed increased specificity toward cells expressing both targeted antigens compared with single-antigen-expressing cells and low activity toward primary cells from healthy tissues. Our findings indicated that the dCAR138-38 may provide a potent and safe alternative therapy for patients with multiple myeloma.

Stratifying risk of infection and response to therapy in patients with myeloma: a prognostic study

BackgroundMultiple myeloma is a cancer of plasma cells that is associated with severe immunodeficiency and increased numbers of bacterial infections. The Tackling Early Morbidity and Mortality in Myeloma (TEAMM) trial assessed the use of prophylactic levofloxacin in newly diagnosed multiple myeloma patients. Interactions between multiple myeloma disease activity, immunity and infection are central to the TEAMM trial. Active multiple myeloma suppresses immunity and infections delay administration of anti-multiple myeloma therapy. Furthermore, infection-derived inflammation nurtures multiple myeloma activity and resistance to anti-multiple myeloma therapy.ObjectivesThe aim of this study was to measure biomarkers of (1) immune competence to develop risk stratification of patients for infection to personalise the decision to prescribe antibiotics, (2) myeloma activity to sensitively measure speed and depth of myeloma response and (3) inflammation to identify patients who may be at risk of poor treatment responses.MethodSerum samples were collected from 977 TEAMM trial patients (aged 35–90 years) at randomisation, then every 4 weeks for 16 weeks and again at 1 year. Biomarker levels were compared with samples from healthy controls. Multiplex Luminex®assays (R&D Systems, Minneapolis, MN, USA) and enzyme-linked immunosorbent assays were used for the analysis of biomarkers and anti-viral antibodies were measured by a haemagglutination assay.ResultsAt baseline, levels of both polyclonal immunoglobulins and anti-bacterial antibodies were below the normal range in most TEAMM trial patients. This immunoparesis was much more severe for antibodies against specific bacterial targets than for total immunoglobulin levels. Levels of anti-bacterial antibodies were below the threshold of protection for 18 of the 19 bacterial antigens tested. More patients aged < 65 years were protected against meningococcal serotypes,Haemophilus influenzatype b and tetanus, whereas more patients aged ≥ 65 years were protected against pneumococcal serotypes but there was good protection in only 6% of the TEAMM trial patients. Higher levels of polyclonal immunoglobulins, but not specific anti-bacterial antibodies, were found to be associated with a lower risk of infection and a longer survival. At presentation, levels of neutrophil elastase, calprotectin and interleukin 10 were elevated in TEAMM trial patients, compared with healthy controls. Interleukin 10 levels were related to infection during the trial: patients with interleukin 10 levels ≥ 10 pg/ml had a greater risk of infection than patients with interleukin 10 levels < 10 pg/ml. Levels of soluble CD138 were elevated in 72% of TEAMM trial patients and were decreased in response to therapy, with a complete response seen in 40% of TEAMM trial patients by 16 weeks. Of the 76 TEAMM trial patients achieving a free light chain complete response at 16 weeks, only 30% had a soluble CD138 complete response. Overall, responses in the levels of soluble CD138 did not correlate with free light chain and myeloma monoclonal protein (also known as m-protein) responses, consistent with the fact that soluble CD138 responses reflect a separate aspect of disease activity and clonal size. Levels of procalcitonin were elevated in only 50% of patients who had febrile episodes during the TEAMM trial. Although levels of interleukins 6 and 8 at presentation were lower than in a heathy cohort of patients, lower levels of interleukin 6 were identified at baseline in poor responders than in good responders, and in patients who had febrile and non-febrile infections during the trial than in patients who had only non-febrile episodes.ConclusionInformation from this Efficacy and Mechanism Evaluation project can help inform risk stratification and patient identification strategies to be responsive to individual patient needs. Monitoring levels of free light chains and soluble CD138 can help identify non-responders early and monitoring interleukin 10 levels can help stratify patients for risk of infection. Furthermore, immunisation in remission should be tested.LimitationsThe TEAMM trial administered prophylactic antibiotics or placebo for 12 weeks from a new diagnosis of myeloma. Patients were monitored for infections for 16 weeks post diagnosis, with a final set of clinical data gathered at 1 year. Infection data and efficacy of prophylactic antibiotics are available for only the first 16 weeks and survival for the first 52 weeks. This limits long-term data, particularly for progression-free and overall survival.Future workThe TEAMM 2 trial (in preparation) will explore the benefit of prophylactic antibiotics up to 12 months following diagnosis and will explore infection risk post therapy and during remission. Furthermore, some of the key findings will be applied to investigate biomarkers in samples from other UK myeloma trials in which long-term outcome data are available.Trial registrationCurrent Controlled Trials ISRCTN51731976.FundingThis project was funded by the Efficacy and Mechanism Evaluation programme, a Medical Research Council and National Institute for Health Research (NIHR) partnership, and will be published in full inEfficacy and Mechanism Evaluation; Vol. 7, No. 10. See the NIHR Journals Library website for further project information.

Monitoring treatment response and disease progression in myeloma with circulating cell‐free DNA

Circulating cell-free DNA (cfDNA) has the potential to capture spatial genetic heterogeneity in myeloma (MM) patients. We assessed whether cfDNA levels vary according to risk status defined by the 70 gene expression profile (GEP70). cfDNA levels in 77 patients were significantly higher in the GEP70 high-risk (HR) group compared to the low-risk (LR) group and correlated weakly with clinical markers including lactate dehydrogenase, β2 -microglobulin, and ISS. Patients with high cfDNA levels were associated with a worse PFS (hazard ratio 6.4; 95% CI of ratio 1.9-22) and OS (hazard ratio 4.4; 95% CI of ratio 1.2-15.7). Circulating tumor DNA (ctDNA) was elevated in the HR group and ctDNA correlated strongly with GEP70 risk score (Spearman r=.69, P=.0027). cfDNA concentrations were significantly elevated between days 3-5 after chemotherapy before falling back to baseline levels. ctDNA in two patients showed a similar spike in levels between days 3 and 5 after chemotherapy with a concomitant increase in allele fraction of KRAS mutations. We assessed cfDNA levels in 25 patients with smoldering myeloma with serial samples and showed increased allele fraction of mutated KRAS at progression in cfDNA. Our study shows that cfDNA is a dynamic tool to capture genetic events in myeloma.

TAK-573, an Anti-CD38/Attenuated Ifnα Fusion Protein, Has Clinical Activity and Modulates the Ifnα Receptor (IFNAR) Pathway in Patients with Relapsed/Refractory Multiple Myeloma

TAK-573, an Anti-CD38/Attenuated Ifnα Fusion Protein, Has Clinical Activity and Modulates the Ifnα Receptor (IFNAR) Pathway in Patients with Relapsed/Refractory Multiple Myeloma

Bone Marrow-Derived Mesenchymal Stem Cells Inhibit CD8+ t Cell Immune Responses Via PD-1/PD-L1 Pathway in Multiple Myeloma

High expression of the inhibitory receptor programmed death ligand 1 (PD-L1) on tumor cells and tumor stromal cells have been found play a key role in tumor immune evasion in several human malignancies. However, the expression of PD-L1 on bone marrow mesenchymal stem cells (BMSCs) and whether the PD-1/PD-L1 signal pathway is involved in the BMSCs versus T cell immune response in Multiple Myeloma (MM) remain poorly defined. In this study, we explored the expression of PD-L1 on BMSCs from newly diagnosed MM (NDMM) patients and the role of PD-1/PD-L1 pathway in BMSCs-mediated regulation of CD8+T cells. The data showed that the expression of PD-L1 on BMSCs in NDMM patients was significantly increased than that in normal controls (NC) (18.81±1.61% vs. 2.78±0.70 %; P<0.001). Furthermore, the PD-1 expression on CD8+T cells with NDMM patients was significantly higher than that in normal controls (43.22±2.98% vs. 20.71±1.08%; P<0.001). However, there was no significant difference in PD-1 expression of CD4+ T cells and NK cells between NDMM group and NC group. Additionally, the co-culture assays revealed that BMSCs significantly promoted CD8+ T cells apoptosis and suppressed CD8+ T cells function. However, PD-L1 inhibitor effectively reversed BMSCs-mediated suppression in CD8+ T cells. We also found that the combination of PD-L1 inhibitor and pomalidomide can further enhance the killing effect of CD8+ T cells on MM cells. In summary, our findings demonstrated that BMSCs in patients with MM may induce apoptosis of CD8+T cells through the PD-1/PD-L1 axis and inhibit the release of perforin and granzyme B from CD8+ T cells so as to promote the immune escape of MM. Disclosures No relevant conflicts of interest to declare.

Relapse from MRD Negativity As Indication for Treatment in Multiple Myeloma - the Remnant Study

Background: Early intervention can reduce the rate of progression and improve overall survival (OS) in smouldering multiple myeloma (SMM) patients (pts) (1, 2). The most powerful predictor of prognosis in active MM is whether pts achieve minimal residual disease (MRD) negativity in bone marrow with treatment (3), however treating MRD relapse has not been evaluated in a randomized fashion. The REMNANT study will evaluate whether treating MRD relapse after first line (1.L) treatment prolongs progression free survival (PFS) and OS for MM pts versus treating relapse after 1.L. treatment at progressive disease (PD) (4). To establish a homogenous group of MRD negative pts after 1.L treatment including autologous stem cell transplantation (ASCT), pts are enrolled at diagnosis and treated with Norwegian standard of care (SOC) 1.L treatment. MRD negative pts will move on to the randomized part. Methods: The REMNANT study is an academic, multicenter, open-label, randomized phase II/III study of NDMM pts eligible for ASCT (see Figure 1). 391 pts across Norway will be included in the phase II part of the study and receive SOC 1.L treatment according to Norwegian national guidelines; VRd (V: 1,3 mg/m2 SC Days 1, 4, 8, 11; R: 25 mg PO Days 1-14; d: 20 mg PO Days 1, 2, 4, 5, 8, 9, 11, 12) for 4 pre-transplant induction and 4 post-transplant consolidation cycles (all 21-d cycles). After induction pts will undergo tandem or single ASCT, depending on toxicity and response to first ASCT. The primary endpoint of the phase 2 part of the study is the number of pts who achieve MRD negative (Euroflow NGF 10 -5) complete response (CR) 30-45 days post consolidation. Safety evaluations and pts-reported outcome assessment will be measured. Pts (176) achieving MRD negative CR will be randomly assigned in a 1:1 ratio to receive 2.L treatment at MRD reappearance (arm A) or at progressive disease (PD) as defined by the IMWG criteria (4) (arm B). Randomization will be stratified by R-ISS stage at diagnosis and single vs tandem ASCT. Pts in arm A will be followed with MRD assessment every 4 month and start 2.L treatment at loss of MRD negative CR. Pts in arm B will be followed up by standard criteria and start 2.L treatment at PD. Both arms will receive the same 2.L treatment; KdD (all 28-d cycles) (K: 70mg/m2 iv Days 1,8,15 d: 40 mg Days 1, 8, 15, 22 D: 1800 mg SC Days 1, 8, 15 during C 1-2, Days 1, 8 during cycle 3-6, Day 1 from cycle 7,). 2.L treatment will continue until disease progression, unacceptable AEs or patient withdrawal. In arm A MRD Euroflow will be assessed after 6 and 18 months of 2L therapy. In arm B MRD Euroflow will be assessed if >CR is achieved but not before 6 months of 2 L therapy, and again after 12 consecutive months. The co-primary endpoint is progression and death by any cause (PFS) and death by any cause alone (OS). Secondary endpoints includes TTNT and the proportion pf pts who achieve MRD negative CR during 2.L treatment in arm A and arm B, safety evaluations and pts-reported outcome. The trial is approved and will start enrollment Q3 2020. 1. Mateos MV, Hernandez MT, Giraldo P, de la Rubia J, de Arriba F, Corral LL, et al. Lenalidomide plus dexamethasone versus observation in patients with high-risk smouldering multiple myeloma (QuiRedex): long-term follow-up of a randomised, controlled, phase 3 trial. Lancet Oncol. 2016;17(8):1127-36. 2. Lonial S, Jacobus S, Fonseca R, Weiss M, Kumar S, Orlowski RZ, et al. Randomized trial of lenalidomide versus observation in smoldering multiple myeloma. 2020;38(11):1126-37. 3. Munshi NC, Avet-Loiseau H, Rawstron AC, Owen RG, Child JA, Thakurta A, et al. Association of Minimal Residual Disease With Superior Survival Outcomes in Patients With Multiple Myeloma: A Meta-analysis. JAMA Oncol. 2017;3(1):28-35.5. 4. Kumar S, Paiva B, Anderson KC, Durie B, Landgren O, Moreau P, et al. International Myeloma Working Group consensus criteria for response and minimal residual disease assessment in multiple myeloma. Lancet Oncol. 2016;17(8):e328-e46. Disclosures Schjesvold: Amgen, Celgene, Janssen, MSD, Novartis, Oncopeptides, Sanofi, SkyliteDX, Takeda: Honoraria; Celgene, Amgen, Janssen, Oncopeptides: Research Funding; Amgen, Celgene, Janssen, MSD, Novartis, Oncopeptides, Sanofi, Takeda: Consultancy. OffLabel Disclosure: Carfilzomib-dexamethason-daratumumab (KdD) as second line treatment

Interactions with a “Humanized” Mesenchymal Bone Marrow Stromal Niche In Vivo Modify the Patterns of Essential Genes for Myeloma Cells: Therapeutic Implications

Background: The biology and treatment response of human multiple myeloma (MM) cells in vivo is influenced by interactions with mesenchymal bone marrow stromal cells (BMSCs). For several key BMSC-derived cytokines (including IL-6) only the human, not murine, form optimally interacts with their respective receptor(s) on human MM cells. To better simulate the treatment responses of human MM cells in the BM, "humanized" BM-like niches in vivo have been engineered with biocompatible ceramic scaffolds "functionalized" via osteogenic differentiation of human mesenchymal BMSCs and implanted subcutaneously in immunocompromised mice. Aim: To determine if the patterns of genetic dependencies elucidated through in vitro CRISPR-based functional genomic studies are recapitulated when human MM cells are grown in mice within BM-like scaffolds with "humanized" mesenchymal stromal compartment. Methods: Cas9+ MM cell lines KMS11 and XG7 were transduced with a library of 1372 single-guide RNAs (sgRNAs) targeting 184 genes of interest (4 sgRNAs/gene), including 89 genes preferentially essential for MM cell lines compared to other neoplasms in vitro; broad-spectrum oncogenic targets (e.g. KRAS, MYC); tumor suppressor genes (e.g. PTEN); genes with limited in vitro essentiality in MM cells, but significantly higher expression vs. non-MM lines (e.g. ZFP91, ZBP1); and 155 olfactory receptor (OR) genes (typically not expressed or biologically inactive in tumor cells) as "DNA cutting" control sgRNAs. MM cells transduced with this focused CRISPR knockout (KO) library were injected into "humanized" scaffolds implanted subcutaneously (s.c.) in NSG mice. Tumors were collected when mice reached criteria for euthanasia and next-generation sequencing quantified the changes in sgRNA distribution at the end vs. start of experiment. Results: A large majority of genes defined by in vitro CRISPR KO screens as MM-preferential dependencies were also essential for MM cells in BM-like scaffolds. Among 57 MM-preferential dependencies in vitro which were plausible dependencies for KMS11 cells (e.g. CERES scores <-0.4), 50 genes were essential for KMS11 cells in BM-like scaffolds in vivo (average log2fold change<-1.0 and depletion of 3+ of 4 sgRNAs relative to the 99% confidence interval for control sgRNAs). These genes included key transcription factors/cofactors (e.g. IRF4, PRDM1, POU2AF1, RELB, MAF); epigenetic regulators (e.g. CARM1, MTA2, DOT1L); kinases upstream of NFkappaB (CHUK, IKBKB); ER regulators (e.g. SYVN1). Most "core-essential" or broad-spectrum oncogenic dependencies (e.g. MYC, CFLAR, CDK7 on both lines; KRAS in XG7) of this sgRNA library remained essential in vivo; while PTEN KO cells were enriched. Notably, several genes had more pronounced essentiality in vivo vs. invitro (e.g. BCL2, PIM2); or converted from non-essential in vitro to essential in vivo. For instance, among 95 genes of this library which are not likely dependencies in vitro (CERES scores >-0.4) for KMS11 cells, 29 genes exhibited in vivo essentiality for both KMS11 and XG7 cells: several of these latter "in vivo dependencies" are recurrently essential for other MM lines in vitro (e.g. ZBTB38, UBE2J1, TCF3, DNAJB11), while also others have limited if any in vitro essentiality (e.g. ZBP1, PYGO2) across MM despite significantly higher transcript levels vs. other neoplasias. Notably, several genes with increased essentiality in the "humanized" BM scaffolds vs. in vitro also had stronger in vivo dependency in the BM scaffolds vs. when growth of the same MM cells as s.c. plasmacytomas (e.g. BCL2, PIM2, UBE2J1, SYVN1, ALG9, AMFR). Co-culture with BMSCs or IL-6 treatment induces several of these transcripts in MM cells suggesting that increased dependency of MM on these genes in the "humanized" BM model is due at least partly to its human cytokines. Conclusions: This study provides evidence for significant impact of the "humanized" BM-like niche on the patterns of genetic dependencies for human MM cells. Most genes preferentially essential for MM cells in vitro remain essential for their in vivo growth in the "humanized" BM model. Notably, several genes that do not meet criteria for dependency in vitro show such metrics in "humanized" BM scaffolds, but not sc plasmacytomas. These observations highlight important implications of the "humanized" BM-like in vivo model for current and future efforts to define and prioritize therapeutic targets for MM. Disclosures Downey-Kopyscinski: Rancho BioSciences, LLC: Current Employment. Tsherniak:Tango Therapeutics: Consultancy; Cedilla Therapeutics: Consultancy. Boise:AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genetech: Membership on an entity's Board of Directors or advisory committees. Mitsiades:FIMECS: Consultancy, Honoraria; Takeda: Other: employment of a relative; Fate Therapeutics: Consultancy, Honoraria; Janssen/Johnson & Johnson: Research Funding; Arch Oncology: Research Funding; TEVA: Research Funding; Sanofi: Research Funding; Karyopharm: Research Funding; EMD Serono: Research Funding; Abbvie: Research Funding; Ionis Pharmaceuticals, Inc.: Consultancy, Honoraria.

Plasma Cell Leukemia: A Retrospective Review of Cases at Monter Cancer Center/Northwell Health Cancer Institute 2014-2019

Title: Plasma Cell Leukemia: A retrospective review of cases at Monter Cancer Center/Northwell Health Cancer Institute 2014-2019 Background: Plasma cell leukemia (PCL) is an aggressive form of multiple myeloma with an acute onset and a median overall survival (OS) of 13 months.1,2 The defining criteria for PCL is in flux. Prior criteria supported diagnosis of PCL based on the presence of at least 20% clonal plasma cells in the peripheral blood3, while more recent data suggest the use of 5% based on cases with 5-19%.1 The benefit of novel targeted therapy in patients with PCL has begun to be elucidated.2,4 It is difficult to perform prospective studies on patients with PCL due to its fulminant course1,2, changing perspectives on diagnostic criteria1,2,3, and the fact that there is no clear guidance as to what treatment regimens work best in these patients. With the emergence of novel treatment options, such as Daratumumab, the impact on survival in these patients is important to evaluate.2 Aim: Our goal is to gather more information about the treatment approach to patients with PCL in an effort to identify regimens associated with better OS. We hypothesize that patients diagnosed with PCL have improved outcomes when treated with newer FDA approved therapies2, such as Daratumumab2,5,6, compared with traditional therapy. Methods: Using a retrospective study approach, we performed a chart review of patients diagnosed with PCL (primary and secondary) in the Northwell Health system from 2014-2019. Patients were identified at a single center site - Monter Cancer Center. Using the electronic medical records (EMR), patient chart analysis was done to collect baseline patient demographics, diagnoses, cytogenetics, fluorescence in-situ hybridization (FISH) results, laboratory results, treatment regimens, time to progression (TTP), progression-free survival (PFS), and OS. All included patients have a diagnosis of PCL, defined as per the Internal Myeloma Working Group (IMWG) diagnostic criteria.7,8,9 We will correlate survival outcomes (PFS and OS) to treatment regimen used. Results: A total of 10 patients with PCL has been identified. Fifty percent of the patients were male. Ages ranged from 47 - 82 years with a mean age of 65.2 and a median age of 62. Further analysis is in progress. Conclusion: PCL is an aggressive malignancy and an area of unmet need.2,4,7 Due to its fulminant course and the lack of prospective clinical trials in PCL, the optimal therapeutic approach remains controversial.2 This study may potentially highlight the impact of newer therapies for PCL. We propose that further multi-institutional prospective studies in PCL will be important to determine better treatment. References Ravi P, Kumar SK. (2018). Revised diagnostic criteria for plasma cell leukemia: results of Mayo Clinic study with comparison of outcomes to multiple myeloma. Blood Cancer, 8(12). Ngu S, et al. (2019). Primary plasma cell leukemia: A case report and review of the literature. Clin Case Rep, 7(9). Kyle RA, et al. (1974). Plasma cell leukemia. Report on 17 cases. Arch Intern Med, 133(5). Gonsalves WI, et al. (2018). Combination therapy incorporating Bcl-2 inhibition with Venetoclax for the treatment of refractory primary plasma cell leukemia with t (11;14). Eur J Haemotol, 100(2). Center for Drug Evaluation and Research. (2019, September 26). FDA approves daratumumab for transplant-eligible multiple myeloma. https://www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-daratumumab-transplant-eligible-multiple-myeloma. Center for Drug Evaluation and Research. (2020, May 1). FDA approves daratumumab and hyaluronidase-fihj for multiple myeloma. https://www.fda.gov/drugs/drug-approvals-and-databases/fda-approves-daratumumab-and-hyaluronidase-fihj-multiple-myeloma. De Larrea CF, Kyle RA, et al. on behalf of the International Myeloma Working Group (2013). Plasma cell leukemia: consensus statement on diagnostic requirements, response criteria, and treatment recommendations by the International Myeloma Working Group (IMWG). Leukemia 27. Kumar SK, et al. (2016). International Myeloma Working Group consensus criteria for response and minimal residual disease assessment in multiple myeloma. Lancet Oncol. 17(8), e328-e346. Gundesen MT, et al. (2019). Plasma Cell Leukemia: Definition, Presentation, and Treatment. Cur Oncol Rep. 21(1). Disclosures No relevant conflicts of interest to declare.

FT576: Multi-Specific Off-the-Shelf CAR-NK Cell Therapy Engineered for Enhanced Persistence, Avoidance of Self-Fratricide and Optimized Mab Combination Therapy to Prevent Antigenic Escape and Elicit a Deep and Durable Response in Multiple Myeloma

Multiple redundancy within the spectrum of an immune response is required to prevent antigen escape or adaptation of the targeted population to host defenses. As adoptive cell therapies continue to evolve, multi-modal engineering of effector cells offers the prospect of tackling increasingly complex disease settings such as multiple myeloma (MM), where targeting of a single tumor associated antigen is frequently confounded by antigen shedding and escape variation resulting in the inability to develop a curative therapy. There are multiple advantages in expanding treatment options beyond autologous primary T and NK cells, including the use of induced pluripotent stem cells (iPSC) to derive effector cells that can be uniformly manufactured at scale from renewable starting cellular material and where precision genetic engineering can be achieved at the clonal level which can be applied sequentially in order to build multiple specificities and functional modalities. To create a platform targeted toward MM, a multiplexed edited base iPSC-derived NK (iNK) cell configuration consisting of a CD38 KO iPSC modified to overexpress a recombinant IL-15 signaling complex (IL15RF) for autonomous persistence and a functionally enhanced high-affinity, non-cleavable CD16 (hnCD16) was developed. Introduction of IL15RF enabled expansion of iNK cells without additional exogenous cytokine support during the manufacturing process and greatly improved functional persistence of iNK cells both in vitro and in various xenograft mouse models (Figure 1). To target MM in a broad and comprehensive manner, we tested our novel BCMA-CAR in combination with different myeloma targeted antibodies. In combination with hnCD16, co-expression of BCMA-CAR and IL15RF culminates in an iNK cell therapeutic, termed FT576, capable of multiantigen-specificity through combinatorial use of CAR and hnCD16 with monoclonal antibodies to tackle antigen escape. Chimerization of an anti-BCMA scFv shown to elicit higher affinity onto the CAR platform produced specific in vitro recognition of BCMA+ myeloma cells in short-term and long-term NK cell cytotoxicity assays. Specificity of the BCMA-CAR was demonstrated using NALM6 overexpressing BCMA using a short range 4H caspase assay (NALM6_BCMA EC50 14.4, NALM6wt EC50 39.1, p*<0.0001). Utilizing a long range clearance assay, serial restimulation by repeated rounds of exposure to fresh MM1S MM target cells was tested, showing remarkable persistence and antigen-mediated expansion of CAR function in isolation or combined with antibody through 3 rounds of stimulation in the absence of exogenous cytokine support (Figure 2). Continuous long-range clearance assays demonstrated levels of BCMA targeting activity of FT576 alone was equivalent to primary BCMA-targeted CAR-T cells against a panel of BCMA+ target cells. Utilizing hnCD16, BCMA-CAR was tested in combination with anti-CD38 (daratumumab), anti-SLAMF7 (elotuzumab), or anti-CD19, showing synergistic increase in tumor targeting through various tumor associated antigens (TAAs). Polyfunctionality of FT576 stimulated either through CAR or ADCC was similarly measured by both Isoplexis and single cell RNA sequencing. Specificity for plasma cells was confirmed using primary bone marrow samples from either healthy donors or patients. In animal models, as a monotherapy, FT576 achieved sustained tumor control against disseminated MM1s with persistence profile suggestive of antigen mediated expansion (Figure 3). In combination with daratumumab, FT576 was able to achieve complete clearance of MM1S. Combination with other monoclonal antibodies displayed a similar response demonstrating the unique ability of FT576 to be directed to target multiple TAAs. Together, these studies demonstrate the versatility of FT576 as a highly effective multi-antigen targeting and cost-effective off-the-shelf BCMA-CAR iNK cell product and supports the rational for a first-of-kind Phase I Study as a monotherapy or in combination with therapeutic mAbs targeted to MM-associated surface antigens, driving a path towards a curative therapeutic in MM. Disclosures Goodridge: Fate Therapeutics, Inc: Current Employment. Bjordahl:Fate Therapeutics: Current Employment. Mahmood:Fate Therapeutics, Inc: Current Employment. Reiser:FATE THERAPEUTICS: Current Employment. Gaidarova:Fate Therapeutics, Inc: Current Employment. Blum:Fate Therapeutics: Current Employment. Cichocki:Fate Therapeutics, Inc: Consultancy, Patents & Royalties, Research Funding. Chu:Fate Therapeutics, Inc: Current Employment. Bonello:Fate Therapeutics, Inc: Current Employment. Lee:Fate Therapeutics, Inc.: Current Employment. Groff:Fate Therapeutics, Inc: Current Employment. Meza:Fate Therapeutics, Inc: Current Employment. Chu:Roche Holding AG: Current equity holder in publicly-traded company; Fate Therapeutics, Inc.: Current Employment, Current equity holder in publicly-traded company. Walcheck:Fate Therapeutics: Consultancy, Research Funding. Malmberg:Vycellix: Membership on an entity's Board of Directors or advisory committees; Fate Therapeutics: Consultancy, Patents & Royalties. Miller:Vycellix: Consultancy; Onkimmune: Honoraria, Membership on an entity's Board of Directors or advisory committees; Nektar: Honoraria, Membership on an entity's Board of Directors or advisory committees; Fate Therapeutics, Inc: Consultancy, Patents & Royalties, Research Funding; GT Biopharma: Consultancy, Patents & Royalties, Research Funding. Valamehr:Fate Therapeutics, Inc: Current Employment, Current equity holder in publicly-traded company.

Development of a Hydrashift 2/4 Isatuximab Assay to Mitigate Interference with Monoclonal Protein Detection on Immunofixation Electrophoresis in Vitro Diagnostic Tests in Multiple Myeloma

Introduction Evaluation of multiple myeloma (MM) response through quantification of M-protein, by serum protein electrophoresis (SPEP) and immuno-fixation electrophoresis (IFE) is challenging for clinical laboratories because therapeutic monoclonal antibodies (mAbs) can confound IFE when they converge with serum M-protein. This can be misleading when interpreting patients' response to therapy. Isatuximab (Isa), an IgG-kappa anti-CD38 mAb is approved based on the pivotal ICARIA-MM study in combination with pomalidomide (P) and dexamethasone (d), in the United States, the European Union, Canada, Australia, Switzerland and Japan for the treatment of adult patients with relapsed/refractory MM who have received at least two prior therapies including lenalidomide and a proteasome inhibitor. Recently, the Phase 3 IKEMA study evaluating Isa plus carfilzomib (K) and d met its primary endpoint at the first planned interim analysis, demonstrating significantly prolonged progression free survival (PFS) compared with Kd alone in patients with relapsed MM. Methods To overcome the interference mediated by Isa on the IFE test, we have developed an Isa-specific assay "HYDRASHIFT 2/4 Isa" using a highly specific rabbit, anti-Isa mAb. The HYDRASHIFT 2/4 Isa test is used in conjunction with the regular Hydragel IF procedure and the semi-automated Hydrasys 2 electrophoresis apparatus. The HYDRASHIFT 2/4 Isa test displaces Isa (IgG kappa) interference during the electrophoresis process by forming Isa/anti-Isa complex which is moved out of the gamma zone toward the alpha globulin fractions. Results: Sensitivity of the HYDRASHIFT 2/4 Isa assay was demonstrated on serum samples, including normal serum samples. Isa control and serum samples with different monoclonal components spiked with Isa (final concentrations in the range of 0.1 and 3.0 g/L) were analyzed with the HYDRASHIFT 2/4 Isa procedure used in conjunction with Hydragel 4 IF Acid Violet. The detection limit of Isa and/or the Isa / anti-Isa antibody complex visualized was 0.2 g/L. Importantly, efficient removal of Isa from the gamma globulin zone, with no trace signal evident, was demonstrated for all Isa concentrations tested, even for 3 g/L. Reproducibility of the HYDRASHIFT 2/4 Isa assay was also demonstrated between gels, between product lots, between instruments and on different test days. Ten different serum samples, including 1 normal serum sample and 9 serum samples with monoclonal components spiked with Isa at 1 g/L, were run using the HYDRASHIFT 2/4 Isa procedure in conjunction with Hydragel 4 IF Acid Violet. All samples gave 100% concordant results between gels on the different instruments and with different HYDRASHIFT 2/4 Isa lots. To evaluate specificity, 50 serum samples from MM patients were spiked with 1 g/L Isa and the anti-Isa mAb shifted Isa specifically with no impact on the patients' M-spike, demonstrating 100% specificity. Finally, the HYDRASHIFT 2/4 Isa test was evaluated on 15 samples from treated patients enrolled in Isa clinical trials at different therapy cycles. The evaluated samples demonstrated efficient removal of Isa from G and Kappa tracks on the gamma globulins zone and visualization of the Isa/anti-Isa complex on alpha zone and/or Isa on ELP track. For the pre-treatment samples, there was as expected no Isa detection, and no impact on M-protein was observed, further confirming the specificity of the assay toward Isa. Conclusions Therapeutic mAb inclusion in MM treatment regimens offer patients significant improvements in clinical outcomes. With rapid evolution of therapeutic options in MM, there is a clear need for a standardized and reliable method to ensure authentic IFE-based clinical assessment. Development of the Isa-specific HYDRASHIFT 2/4 Isa assay offers the advantage of high clinical utility due to the simplicity of the method as an add-on to the conventional IFE In vitro diagnostic test. Consequently, this assay will facilitate the correct assessment of clinical outcomes for patients receiving Isa as part of their MM treatment. Submission for global regulatory clearance for Isa-specific HYDRASHIFT 2/4 assay is planned in 2020. Disclosures Finn: Sanofi: Current Employment. Macé:Sanofi: Current Employment. Chu:Sanofi: Current Employment. van de Velde:Sanofi: Current Employment, Current equity holder in publicly-traded company. Melki:Sebia: Current Employment.

External Validation of Diffusion Weighted Whole Body MRI (DW-MRI) Response Assessment Category (RAC) Criteria Proposed By the Myeloma Response Assessment and Diagnosis System (MY-RADS) Imaging Recommendations: Prognostic Role of Imaging Response after Transplant in Multiple Myeloma and Comparison with MRD Evaluation By Flow Cytometry

External Validation of Diffusion Weighted Whole Body MRI (DW-MRI) Response Assessment Category (RAC) Criteria Proposed By the Myeloma Response Assessment and Diagnosis System (MY-RADS) Imaging Recommendations: Prognostic Role of Imaging Response after Transplant in Multiple Myeloma and Comparison with MRD Evaluation By Flow Cytometry

Evaluation of Whole-Body MRI (WB-MRI) in Smoldering Multiple Myeloma (SMM)

Introduction Whole-body magnetic resonance imaging (WB-MRI), including multiplanar multisequence technique with diffusion weighted images, is a novel imaging technique being evaluated for patients with multiple myeloma (MM). WB-MRI is ideal for this population due to its high sensitivity for bone marrow signal changes and full anatomic coverage from vertex to mid-thighs. It is well established that patients with unequivocal focal lesions on MRI have worse outcomes. Currently the IMWG recommends that all patients with smoldering multiple myeloma (SMM) undergo WB-MRI (or whole spine MRI if WB-MRI is not available) to rule out two or more focal lesions which would classify the patient as having symptomatic myeloma requiring treatment. There is a clear benefit of using MRI for the detection of early focal myeloma lesions however less is known about findings in the SMM population. Detection of subtle findings such as one small focal lesion or heterogeneous bone marrow in WB-MRI has unknown clinical significance that needs to be further evaluated. This study aimed to evaluate the sensitivity of WB-MRI compared to other highly sensitive functional imaging modalities in patients with SMM both at baseline and after treatment. Methods Imaging of patients with WB-MRI performed at the National Institutes of Health Clinical Center Myeloma Program were reviewed and compared to whole spine MRI and 18F-FDG PET/CT completed at the same timepoint. The majority of patients were being evaluated for enrollment on clinical trials. Patients had undergone a WB-MRI with a 3-Tesla system either as a baseline study, after completion of induction treatment, or during follow up determined by the time DWI became available at our institution. The imaging protocol included sagittalT1 weighted (W) and Short tau inversion recovery (STIR) for spine and coronal, axial T1W and axial T2 TSE pulse sequences. The functional component included diffusion weighted imaging in the axial plane (b=0 and 900sec/mm2). Radiological interpretation was performed by two readers using myeloma response assessment and diagnosis system (My-RADS) {Messiou, 2019 #340}. WB-MRIs were categorized as positive if focal lesions or diffuse/heterogenous pattern of bone marrow infiltration were present. Similarly, 18F-FDG PET/CTs and whole spine MRIs were classified as positive if focal lesions or diffuse/heterogenous pattern of bone marrow were present. Results A total of 34 patients with SMM and 5 patients with relapsed refractory multiple myeloma (RRMM) had sequential WB-MRI and 18F-FDG PET/CT. Figure 1 summarizes the radiological data of the SMM population. Eleven of these patients had PET/CT, whole spine MRI, and WB-MRI at baseline. Twenty-five patients had PET/CT and WB-MRI completed after at least 8 cycles of treatment. Thirteen patients had consistently negative imaging at baseline, 7 of which also had negative imaging after treatment, while 2 patients were found to have new lesions seen on WB-MRI after treatment. Six patients had resolution of positive imaging seen at baseline after treatment. Among the 17 patients with a positive WB-MRI, 12 (71%; 95% CI 47% - 87%) had a negative correlating PET/CT. Among 5 patients with positive PET/CT at the same time point as a WB-MRI, only 1 (20%; 95% CI 2% - 64%) correlated to a negative WB-MRI. Figure 2 depicts findings from patients with RRMM for comparison. All imaging modalities showed multiple focal findings in all 5 patients. Conclusions This study depicts the high sensitivity of WB-MRI in the SMM population. Such a high sensitivity is especially needed in SMM and early myeloma when disease burden is lower and the decision for treatment is being considered. In comparison to the RRMM population where all three imaging modalities easily detect multiple focal lesions, WB-MRI tends to identify myeloma involvement in the SMM patients more than the other imaging techniques. This suggests the importance of utilizing WB-MRI when diagnosing SMM. In the SMM population, the prognostic significance of lesions that are discrepant between MRI and FDG PET/CT is not yet known. Further follow up is needed to evaluate any difference in hard endpoints such as progression free survival between patients with positive findings described by WB-MRI. Disclosures No relevant conflicts of interest to declare.

Risk of Early Severe Infections in Newly Diagnosed Multiple Myeloma Patients Treated with Novel Agents: A Pooled Analysis

Risk of Early Severe Infections in Newly Diagnosed Multiple Myeloma Patients Treated with Novel Agents: A Pooled Analysis

Role of Imaging in the Evaluation of Minimal Residual Disease in Multiple Myeloma Patients.

The International Myeloma Working Group (IMWG) recently introduced the evaluation of minimal residual disease (MRD) within the multiple myeloma (MM) response criteria, and MRD negativity assessed inside and outside the bone marrow is currently considered the most powerful predictor of favorable long-term outcomes. However, MRD evaluation has thus far relied on flow-cytometry or molecular-based methods, despite the limitations associated with the patchy infiltration of bone marrow (BM) plasma cells and the presence of extra-medullary (EMD). On the contrary, imaging-based sensitive response assessment through the use of functional rather than morphological whole-body (WB) imaging techniques, such as positron emission tomography with computed tomography (PET/CT) and magnetic resonance imaging (MRI), likely is a promising strategy to overcome these limitations in evaluating response to therapy and in the assessment of the MRD status in MM patients. However, despite the significant advances in the development and availability of novel functional imaging techniques for MRD evaluation, a worldwide standardization of imaging criteria for acquisition, interpretation, and reporting is yet to be determined and will be object of future investigations.

Inverse relationship between oligoclonal expanded CD69− TTE and CD69+ TTE cells in bone marrow of multiple myeloma patients

AbstractCD8+CD57+ terminal effector T (TTE) cells are a component of marrow-infiltrating lymphocytes and may contribute to the altered immune responses in multiple myeloma (MM) patients. We analyzed TTE cells in the bone marrow (BM) and peripheral blood (PB) of age-matched controls and patients with monoclonal gammopathy of undetermined significance (MGUS), smoldering MM (SMM), and newly diagnosed (ND) MM using flow cytometry, mass cytometry, and FlowSOM clustering. TTE cells are heterogeneous in all subjects, with BM containing both CD69− and CD69+ subsets, while only CD69− cells are found in PB. Within the BM-TTE compartment, CD69− and CD69+ cells are found in comparable proportions in controls, while CD69− cells are dominant in MGUS and SMM and predominantly either CD69− or CD69+ cells in NDMM. A positive relationship between CD69+TTE and CD69−TTE cells is observed in the BM of controls, lost in MGUS, and converted to an inverse relationship in NDMM. CD69−TTE cells include multiple oligoclonal expansions of T-cell receptor/Vβ families shared between BM and PB of NDMM. Oligoclonal expanded CD69−TTE cells from the PB include myeloma-reactive cells capable of killing autologous CD38hi plasma cells in vitro, involving degranulation and high expression of perforin and granzyme. In contrast to CD69−TTE cells, oligoclonal expansions are not evident within CD69+TTE cells, which possess low perforin and granzyme expression and high inhibitory checkpoint expression and resemble T resident memory cells. Both CD69−TTE and CD69+TTE cells from the BM of NDMM produce large amounts of the inflammatory cytokines interferon-γ and tumor necrosis factor α. The balance between CD69− and CD69+ cells within the BM-TTE compartment may regulate immune responses in NDMM and contribute to the clinical heterogeneity of the disease.

ESTABLISHMENT OF MULTIPLE MYELOMA CELL LINES WITH REDUCED EXPRESSION OF HEPATOCYTE GROWTH FACTOR USING RNAI APPROACH

Objective: To establish the gene knockdown system (RNAi) using different Multiple Myeloma Cell lines (MMCL). Material and Methods: RNAi is generally used in biomedical research to study the outcome of knockdown of gene expression. In this research, retroviral-shRNA expression constructs based on micro RNA-adapted short hairpin RNA (sh RNA mir) were designed and constructed. The sequence of the cloned fragments in the vector constructs was determined, and the effect of constructs in MMCLs was examined using qRT-PCR and Western blot analysis. Results: In this work, we established a method for making retroviral-shRNA expression constructs based on micro RNA-adapted short hairpin RNA (sh RNA mir) design. The HGF producing human myeloma cell line JJN-3 transduced with lentiviral HGF-shRNA transduction particles were analyzed for their effect on the HGF gene expression. HGF knockdown MMCL was analyzed both at mRNA level and protein levels. Two out of five clones of myeloma cell line JJN-3 (JJN3-sh3308 and JJN3-sh47137) were transduced with lentiviral HGF–shRNA transduction particles were showing 50-60 % knockdown in their HGF mRNA and protein expression. Conclusion: HGF knockdown cell lines can be used as tissue culture models to investigate the role of HGF protein in the pathology of multiple myeloma. Further, the retroviral-HGF-shRNA expression constructs can study HGF response in various multiple myeloma via gene knockdown studies.

Propylene Glycol-Free Melphalan versus PG-Melphalan as Conditioning for Autologous Hematopoietic Cell Transplantation for Myeloma

High-dose melphalan (Mel) conditioning before autologous hematopoietic cell transplantation (autoHCT) is standard of care for patients with transplantation-eligible multiple myeloma. The traditional lyophilized Mel formulation has inadequate solubility and stability after reconstitution, leading to the use of propylene glycol (PG) as a solubilizing agent. A newer PG-free Mel preparation (Evomela) uses beta cyclodextrin captisol as a solubilizing agent and was approved by the United States Food and Drug Administration as a conditioning agent based on a single-phase IIb study showing bioequivalence. We compared the outcomes of consecutive patients with myeloma undergoing autoHCT using the 2 formulations of Mel for conditioning as our center switched from using the older formulation (PG-Mel) to the newer one (PGF-Mel). Of 294 autoHCT recipients, 162 received PG-Mel conditioning and 132 received PGF-Mel conditioning. The PGF-Mel group was older and had a lower average Karnofsky Performance Status score. PGF-Mel was associated with faster neutrophil recovery (median, 12 days versus 13 days; P < .001), fewer grade 3-4 infections within 30 days of autoHCT (1.5% versus 8.0%; P=.048), and a lower 30-day rehospitalization rate (6.8% versus 17.9%; P=.04), as confirmed by propensity-weighted analysis. No significant between-group differences were detected in mucositis, organ toxicity, myeloma response, or 100-day mortality.