Dhodapkar, Madhav V.

Compared with traditional bulk sequencing technologies, single-cell technologies have advantages to evaluate cellular heterogeneity and investigate the evolution of cellular subpopulations from the tumor and microenvironment. Application of single-cell sequencing in Multiple Myeloma (MM) is especially beneficial given MM is a highly heterogeneous disease with uncontrolled clonal expansion of plasma cells. Single-cell RNA sequencing (scRNA-seq) has been previously utilized to understand this hematopoietic malignancy in both tumor and immune populations in MM (Ledergor G. et al., 2018, Zavidij, O. et al., 2020). Mass cytometry (CyTOF) has also been used to identify the expansion of novel memory B cells in MM. (Hansmann, L. et al., 2015). Among the various single cell techniques, cellular indexing of transcriptomes and epitopes by sequencing (CITE-seq) is a multimodal approach with simultaneous quantification of single-cell transcriptomes and surface proteins. Since these three single-cell approaches enable the identification of cell types, cell states and characterization of cellular heterogeneity at transcriptomic and/or protein levels, understanding the concordance of the measurements among these three modalities is of great interest. We applied scRNA-seq, CyTOF and CITE-seq on four baseline samples of CD138-negative 'immune cell' fractions from patients enrolled in the MMRF CoMMpass study (NCT01454297). Two subjects were fast progressors (PFS < 18 months) and two subjects were non-progressors (PFS not reached). With multi-center collaboration coordinated by Multiple Myeloma Research Foundation (MMRF), each sample was subject to scRNA-seq and CyTOF by 3 independent centers. All sites received aliquots of the same sample. On average, 1,060 immune cells were detected in each sample using scRNA-seq and >64K CD45+ cells were detected using CyTOF. CITE-seq was performed in one center and 4,805 CD138-negative immune cells were identified on average. To compare cell type abundance between scRNA-seq, CyTOF and CITE-seq, we calculated the cell subset frequency of each immune population relative to the CD45+ populations. Overall, all three approaches were concordant while there is a stronger concordance between scRNA-seq and CyTOF. Cell type abundance is especially consistent for B cells, monocytes/macrophages, and plasmacytoid dendritic cells (pDC) among the 3 methods. For the same patient of interest, natural killer (NK) cell frequency was detected at the lowest level in CyTOF relative to scRNA and CITE-seq. The T cell population showed the highest discrepancy among techniques, with highest abundance in scRNA-seq followed by CyTOF and lowest abundance in CITE-seq. Interestingly, CITE-seq detected far less CD4 T cells compared to the other two techniques while CD8 T cell frequency did not show drastic differences. In addition to cell type abundance, we further examined the concordance of expression of cell type signature genes between scRNA-seq and CyTOF. Overall, expression between RNA-level and protein-level is positively correlated with typical cell type markers highly expressed in both techniques, especially in the following cell populations: CD8+ T cells (CD3, CD8), NK cells (CD56, GranzymeB/GZMB, NKG2A/KLRC1), B cells (CD19, CD38), Monocytes (CD14, CD11c/ITGAX, CD33). To note, although the concordance in CD4+ T cells is generally good, we found the expression of CD4 is higher in CyTOF compared to scRNA-seq whereas CD127/IL7R tends to be overexpressed in scRNA-seq. This could explain why IL7R is often identified as a differentially expressed gene (DEG) in CD4+ T cell population while CD4 is barely seen in DEG list in scRNA-seq analysis. It is also interesting to notice that the expression of most NK cell markers has strong concordance between scRNA-seq and CyTOF except NKG2D/KLRK1, which has much higher expression in CyTOF relative to scRNA-seq. Our preliminary results suggested good concordance of immune cell type abundance identified in CyTOF, scRNA-seq and CITE-seq as well as concordant expression of some canonical cell type markers between RNA level and protein level. This work provides the field with reference data sets and shows more detailed examination of NK and T cell subsets is needed when handling single cell sequencing with different modalities. Disclosures Dhodapkar: Roche/Genentech: Membership on an entity's Board of Directors or advisory committees, Other; Lava Therapeutics: Membership on an entity's Board of Directors or advisory committees, Other; Kite: Membership on an entity's Board of Directors or advisory committees, Other; Janssen: Membership on an entity's Board of Directors or advisory committees, Other; Celgene/BMS: Membership on an entity's Board of Directors or advisory committees, Other; Amgen: Membership on an entity's Board of Directors or advisory committees, Other. Kumar:MedImmune: Research Funding; Amgen: Consultancy, Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments, Research Funding; AbbVie: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Janssen Oncology: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Carsgen: Other, Research Funding; Merck: Consultancy, Research Funding; Adaptive Biotechnologies: Consultancy; Celgene/BMS: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Genentech/Roche: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Oncopeptides: Consultancy, Other: Independent Review Committee; IRC member; Kite Pharma: Consultancy, Research Funding; Novartis: Research Funding; Sanofi: Research Funding; Takeda: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Tenebio: Other, Research Funding; Karyopharm: Consultancy; BMS: Consultancy, Research Funding; Genecentrix: Consultancy; Cellectar: Other; Dr. Reddy's Laboratories: Honoraria. Gnjatic:Neon Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; OncoMed: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Research Funding; Genentech: Research Funding; Immune Design: Research Funding; Agenus: Research Funding; Janssen R&D: Research Funding; Pfizer: Research Funding; Takeda: Research Funding; Regeneron: Research Funding; Merck: Consultancy, Membership on an entity's Board of Directors or advisory committees. Bhasin:Canomiiks Inc: Current equity holder in private company, Other: Co-Founder.

Outcomes in multiple myeloma (MM) have improved dramatically in the last two decades with the advent of novel therapies including immunomodulatory agents (IMiDs), proteasome inhibitors and monoclonal antibodies. In recent years, immunotherapy for the treatment of MM has advanced rapidly, with the approval of new targeted agents and monoclonal antibodies directed against myeloma cell-surface antigens, as well as maturing data from late stage trials of chimeric antigen receptor (CAR) T cells. Therapies that engage the immune system to treat myeloma offer significant clinical benefits with durable responses and manageable toxicity profiles, however, the appropriate use of these immunotherapy agents can present unique challenges for practicing physicians. Therefore, the Society for Immunotherapy of Cancer convened an expert panel, which met to consider the current role of approved and emerging immunotherapy agents in MM and provide guidance to the oncology community by developing consensus recommendations. As immunotherapy evolves as a therapeutic option for the treatment of MM, these guidelines will be updated.

8507 Background: The introduction of immunomodulatory agents, proteasome inhibitors, and autologous stem cell transplantation (ASCT) has improved outcomes for patients with multiple myeloma (MM), but those with high risk MM (HRMM) have a poor long-term prognosis. To date, no trials have addressed optimal treatment for these patients. Methods: S1211 is a randomized phase II trial (NCT01668719) comparing 8 cycles of lenalidomide, bortezomib and dexamethasone (RVd) induction followed by dose-attenuated RVd maintenance until disease progression with or without elotuzumab. Stem cell collection was allowed, but ASCT was deferred until progression. HRMM was defined by one of the following: gene expression profiling high-risk (GEPhi), t(14; 16), t(14; 20), del(17p) or amplification 1q21, primary plasma cell leukemia (pPCL) and elevated serum LDH (> 2X ULN). Median progression-free survival (PFS) was the primary end-point, using a one-sided stratified log-rank test at a one-sided significance level of 0.1. Secondary endpoints included overall response rate (ORR), adverse events (AE), serious adverse events (SAE) and OS. Response was assessed using the IMWG 2009 criteria. Results: S1211 enrolled 103 evaluable patients, RVd n = 54, RVd-Elo n = 49. 75% had ISS II/III, 47% amp1q21, 38% del17p, 12% t(14; 16), 9% GEPhi, 7% pPCL, 5% t(14; 20) and 4% elevated serum LDH (18.5% > 1 feature). With median follow-up of 53 months (mos.), no difference in median PFS was observed [RVd-Elo = 31 mos., RVd = 34 mos.,HR = 0.968 (80% CI = 0.697-1.344), p = 0.449]. No difference in OS was observed [RVd-Elo = 68 mos, RVd = not reached, HR = 1.279 (80% CI: 0.819, 2.000), p-value = 0.478]. 72% pts had > Grade 3 AEs, no differences in the safety profile were observed except >Grade 3 infections (RVd 8%, RVd-Elo 16%), >Grade 3 sensory neuropathy (RVd 8%, RVd-Elo 13%). Conclusions: In the first randomized HRMM study reported to date, the addition of elotuzumab to RVd induction and maintenance did not improve patient outcomes. However, the PFS and OS seen in both arms of the study exceeded the original statistical assumptions and support the role for PI/IMiD combination maintenance therapy for this patient population. The S1211 data will serve as an important benchmark for future HRMM clinical trials. Clinical trial information: NCT01668719 .

Abstract The outcome of patients (pts) with WM, a rare B-cell malignancy, varies widely. The international community has convened a panel to develop a prognostically meaningful staging system for survival after treatment initiation. Toward establishing IPSS, we performed multivariate analyses with bootstrap validation in a series of 587 pts (median age 67, range: 28 to 95, M/F ratio: 1.7) diagnosed between September 1979 and December 2001. Diagnostic and treatment criteria fulfilled recommendations of the 2nd international WM workshop. Front-line treatment was initiated at diagnosis in 69% and 4 mo to 164 mo later in the remaining pts. Criteria for initiation of therapy included cytopenia, constitutional symptoms, organomegaly, hyperviscosity, IgM-related disorders, which pertained to 51%, 44%, 35%, 31% and 13%, respectively. Treatment regimens comprised alkylating agents, fludarabine and rituximab in 369, 195 and 23 subjects, respectively. Baseline parameters included age>65 yr in 57%, Hb≤11.5 g/dL in 65%, platelet count ≤100 x109/L in 9%, granulocyte count ≤1.5 x109/L in 9%, B2M >3 mg/L in 56%, albumin ≤3.5 g/dL in 36% and monoclonal protein >7.0 g/dL in 7%. With a median follow-up of 64 mo (range, 6 mo–182 mo), the median survival after treatment initiation was 87 mo (95%CI 79–103) regardless of the type of therapy applied (p=0.3). Using results of univariate survival analyses, recursive partitioning and martingale residuals analyses, 7 adverse characteristics for inclusion in multivariate analyses were identified during an expert meeting: age >65 yr, platelet count ≤ 100x109/L, B2M >3 mg/L, M-protein >7.0 g/dL, granulocytes ≤1.5 x109/L, Hb ≤11.5 g/dL and albumin ≤3.5 g/dL. The Cox proportional hazard model with stepwise selection selected the first 6 covariates. Bootstrap resampling (500 replicates) validated the selection of the first 4 covariates in at least 80% of the replicates. Selection of at least one of the last 2 covariates in more than 80% of the replicates indicated a correlation between these 2 covariates, and validated the inclusion of Hb only. Using the combination of age, Hb, platelet count, B2M and M-protein, low risk was defined by the presence of ≤1 adverse characteristic except age, high risk by the presence of >2 adverse characteristics; the remaining patients with 2 adverse characteristics or age >65yr had intermediate risk, comprising 27%, 38% and 35% of patients with 5-yr survival rates of 87%, 68% and 36% (p<0.0001), independent of treatment and age. IPSS split each subgroup identified by previous scoring systems (Morel, Merlini, Dhodapkar). Conversely, log-rank test was significant only when the latter prognostic system was assessed in low IPSS-risk pts. Thus the combination of age, B2M, M-protein and blood counts provides simple prognostic model for survival in WM, hopefully serving as an objective basis for initiation of therapy and comparison of treatment results.

8001 Background: Smoldering multiple myeloma (SMM) is a precursor to myeloma, wherein current standard of care is observation (obs). Data from a randomized Spanish trial (Mateos et al, NEJM 2015) suggest that lenalidomide(len)/dexamethasone improves time to developing myeloma (TTP) and overall survival (OS) for patients (pts) with high risk (HR) SMM over obs. However, pts were not screened with advanced imaging techniques, used a HR definition that is not routinely available, and combination therapy limited the ability to isolate the effect of len, and thus has not become standard of care. Methods: E3A06 is a randomized phase III intergroup trial, testing the effect of single agent len compared with obs for pts with intermediate or high risk SMM. In an initial phase II run in all pts received len to demonstrate safety. Eligibility required ≥10% PCs and abnormal serum FLC ratio (<0.26 or >1.65). The primary endpoint was progression PFS was estimated by the Kaplan-Meier method and compared using the one-sided stratified log-rank test. Results: PII enrolled 44 pts and PIII randomized 182 pts to either len (n=90) or obs (n=92) [stratified on time since SMM diagnosis ≤1y vs >1y]. Baseline characteristics were similar between the arms. 80% (PII) and 51% (PIII) are off len, primarily due to adverse events (AE) or pt withdrawal. Among the len treated pts, G3/4 non-hematologic AE occurred in 28% of PIII pts with fatigue being most common (n=5). G4 hematologic AE rate was 5.7%, primarily neutropenia (n=4). 3-year cumulative incidence of invasive SPMs was 5.2% (len) and 3.5% (obs). Overall response rate was 47.7% for the phase II study, and in phase III, 48.9% for the len arm, and 0% for the obs arm. Median follow up was 71 months (PII), and 28 months (PIII). 3-year PFS was 87% for the PII cohort. One, 2 and 3-year PFS was 98%, 93%, and 91% for len, and 89%, 76%, and 66% for the obs arm (HR 0.28, p=0.0005) favoring the len arm. No difference in QOL score was noted between arms. Conclusions: Overall, this trial represents the largest randomized trial in SMM to date. In conjunction with the Spanish data, this trial may support a change in clinical practice. Clinical trial information: NCT01169337. [Table: see text]

PURPOSE Observation is the current standard of care for smoldering multiple myeloma. We hypothesized that early intervention with lenalidomide could delay progression to symptomatic multiple myeloma. METHODS We conducted a randomized trial that assessed the efficacy of single-agent lenalidomide compared with observation in patients with intermediate- or high-risk smoldering multiple myeloma. Lenalidomide was administered orally at a dose of 25 mg on days 1 to 21 of a 28-day cycle. The primary end point was progression-free survival, with disease progression requiring the development of end-organ damage attributable to multiple myeloma and biochemical progression. RESULTS One hundred eighty-two patients were randomly assigned—92 patients to the lenalidomide arm and 90 to the observation arm. Median follow-up is 35 months. Response to therapy was observed in 50% (95% CI, 39% to 61%) of patients in the lenalidomide arm, with no responses in the observation arm. Progression-free survival was significantly longer with lenalidomide compared with observation (hazard ratio, 0.28; 95% CI, 0.12 to 0.62; P = .002). One-, 2-, and 3-year progression-free survival was 98%, 93%, and 91% for the lenalidomide arm versus 89%, 76%, and 66% for the observation arm, respectively. Only six deaths have been reported, two in the lenalidomide arm versus four in the observation arm (hazard ratio for death, 0.46; 95% CI, 0.08 to 2.53). Grade 3 or 4 nonhematologic adverse events occurred in 25 patients (28%) on lenalidomide. CONCLUSION Early intervention with lenalidomide in smoldering multiple myeloma significantly delays progression to symptomatic multiple myeloma and the development of end-organ damage.

Abstract The treatment and natural history of smoldering myeloma has been an area of intense preclinical and clinical study. Historical attempts to treat these patients have not demonstrated benefit, likely as a consequence of lack of attention to the vast heterogeneity contained within the diagnosis. More recent risk criteria from both US and Spanish investigators have identified a cohort of smoldering myeloma patients at high risk for progression in a short time, using different methodology. Recently the PETHEMA group published a randomized clinical trial testing lenalidomide/dexamethasone vs observation among high risk smoldering patients, and demonstrated a clear benefit in terms of progression free and overall survival favoring early intervention. However, the risk criteria utilized a highly sensitive method of flow cytometry, a test not routinely available in the US. It is not clear that the group of patients defined in the PETHEMA study share similar outcomes with those defined as high risk using the ECOG/Mayo criteria. A recent publication demonstrated only 25% overlap for the highest risk smoldering patients when using either the PETHEMA or the ECOG criteria. To further evaluate the potential benefit of early intervention in a high risk smoldering cohort, the ECOG myeloma group designed a phase II/III trial testing the safety and efficacy of single agent lenalidomide. We report here on the safety and efficacy of the phase II portion of the trial. The phase II group of patients received lenalidomide alone at a dose of 25 mg days 1-21 every 28 days. The primary endpoint for the safety study was the rate of any treatment-related grade 4-5 non-hematologic toxicity plus grade 3 non-hematologic toxicity that affects vital organ function (such as cardiac, hepatic, or thromboembolic events) observed within 6 cycles of treatment. Patients were to be diagnosed with high-risk smoldering multiple myeloma (SMM) within the past 12 months, as confirmed by both of the following: bone marrow plasmacytosis with >= 10% plasma cells or sheets of plasma cells and an abnormal serum free light chain ratio (<0.125 or >8.0) by serum FLC assay. Patients must have had measurable levels of monoclonal protein. Patients must have had no lytic lesions on skeletal surveys and no hypercalcemia (i.e. >= 11 mg/dL). Among the final phase II cohort (n=44 patients), 55% were female, and 43% were 65 years and older. Enrollment began in January 2011 and lasted 2 years with the last patient completing 6 cycles of treatment in August 2013. The median treatment duration of the entire cohort is 13.5 cycles (range 1-30 cycles). Mean percentage lenalidomide dose over the first 6 cycles was 94, 89, 82, 79, 76, 72. With a median follow up of 17 months, 2 patients had progression on therapy. Fifteen patients are off treatment for the following reasons: disease progression (n=2), AE/complication (n=5), death (n=2), patient withdrawal/refusal (n=5), other (n=1); 6 of the 15 patients ended treatment before completing 6 cycles. Of 44 patients assessed for toxicity, 11 patients [25.0%, 95% CI: (13.2%-40.3%)] experienced worst grade treatment-related non-hematologic toxicity of grade 3 or higher based on CTCAE v4, with neutropenia and fatigue being the most frequent. This includes 2 fatal deaths (MI and TE). Two patients [4.6%, 95% CI: (0.1%-15.5%)] experienced a serious adverse event as defined for the purposes of the phase II toxicity analysis that included treatment-related grade 4-5 non-hematologic toxicity or any grade 3 toxicity affecting vital organ function (such as cardiac, hepatic, or thromboembolic events) during the first 6 cycles of treatment. Twelve patients achieved partial response or better [33.3%, 95% CI: (15.0%-42.8%)] along with 25 patients reporting stable disease. Lenalidomide has shown promise in the treatment of high-risk smoldering myeloma and based on this analysis, accrual to the phase III portion is ongoing. In the context of the encouraging data from the PETHEMA group, completion of the phase III portion of this study is needed to validate their findings using a different criteria, and using a steroid sparing approach. This study was coordinated by the Eastern Cooperative Oncology Group (Robert L. Comis, M.D., Chair) and supported in part by Public Health Service Grants CA23318, CA66636, CA21115, CA13650, CA32102 and from the National Cancer Institute, National Institutes of Health and the Department of Health and Human Services. Disclosures: Lonial: Millennium: Consultancy; Celgene: Consultancy; Novartis: Consultancy; BMS: Consultancy; Sanofi: Consultancy; Onyx: Consultancy.

Abstract Abstract 4079 The treatment and natural history of asymptomatic or smoldering myeloma has been an area of intense preclinical and clinical study. Historical attempts to treat these patients have not demonstrated significant benefit, likely as a consequence of limited therapeutic options as well lack of attention to the vast heterogeneity contained within the diagnosis of smoldering myeloma. More recent risk criteria from both US and Spanish investigators have identified a cohort of smoldering myeloma patients at high risk for progression to myeloma in a short time. Recently the PETHEMA group has conducted a randomized clinical trial testing lenalidomide and dexamethasone vs observation among high risk smoldering patients and has demonstrated a clear benefit in terms of progression free survival and hints towards improvement in overall survival favoring early intervention. To further evaluate the potential benefit of early intervention in a high risk smoldering cohort, the ECOG myeloma group designed a phase II trial testing the safety and efficacy of single agent lenalidomide with the intent of broadening to a randomized phase III trial if toxicity was acceptable. We report here on the safety portion of the phase II trial. The phase II group of patients received lenalidomide at a dose of 25 mg days 1–21 every 28 days to evaluate the early toxicity and tolerance of this dosing. The dose of lenalidomide could be adjusted based on toxicity using a defined dose-modification guideline in the protocol. The primary endpoint for the safety study was the rate of any treatment-related grade 4–5 non-hematologic toxicity plus grade 3 non-hematologic toxicity that affects vital organ function (such as cardiac, hepatic, or thromboembolic events) observed within 6 cycles of treatment. The goal was to enroll 34 patients; if 9 or more patients experience toxicity as defined, then the study would not continue. In terms of eligibility, patients were to be diagnosed with asymptomatic high-risk smoldering multiple myeloma (SMM) within the past 12 months, as confirmed by both of the following: bone marrow plasmacytosis with >= 10% plasma cells or sheets of plasma cells and an abnormal serum free light chain ratio (<0.125 or >8.0) by serum FLC assay. Further, patients must have measurable levels of monoclonal protein (M-protein): >=1g/dL on serum protein electrophoresis or >=200 mg of monoclonal protein on a 24 hour urine protein electrophoresis. Patients must have no lytic lesions on skeletal surveys and no hypercalcemia. Among the 36 patients enrolled in the phase II study, 56% were female, and 44% were 65 years and older. Treatment and toxicity data at a minimum through cycle 6 is complete as of August 2, 2102. The last patient enrolled completed cycle 6 treatment on June 7, 2012. The median treatment duration of the entire cohort is 9 cycles (range 1–18 cycles), with 86% of patients completing at least 6 cycles of treatment. Ten patients are off treatment for the following reasons: disease progression (n=1), AE/complication (n=5), death (n=1) and patient withdrawal/refusal (n=3); 5 of the 10 patients ended treatment before completing 6 cycles. Of 36 patients assessed for toxicity, 8 patients [22.2%, 90% CI: (11.6%-36.5%)] experienced worst grade treatment-related non-hematologic toxicity of grade 3 or higher. Separately, 6 patients experienced unrelated non-hematologic toxicity of grade 3 or higher. Three patients [8.3%, 90% CI: (2.3%-20.2%)] experienced a serious adverse event as defined for the purposes of the phase II toxicity analysis (treatment-related grade 4–5 non-hematologic toxicity or grade 3 non-hematologic toxicity that affects vital organ function (such as cardiac, hepatic, or thromboembolic events). Based upon this analysis of the study, the phase II portion of the trial met the prespecified safety benchmark established to allow for phase III expansion, and accrual to the phase III portion of this study will begin. Efficacy data will be presented at the time of presentation. Disclosures: Lonial: Novartis: Consultancy; Millennium: Consultancy; Onyx: Consultancy; BMS: Consultancy; Celgene Corp: Consultancy; Merck: Consultancy. Off Label Use: Lenalidomide is not approved for treatment of smoldering MM. Fonseca:Medtronic: Consultancy; Otsuka: Consultancy; Celgene: Consultancy; Genzyme: Consultancy; BMS: Consultancy; Lilly: Consultancy; Onyx: Consultancy; Binding site: Consultancy; Millenium: Consultancy; AMGEN: Consultancy; Celgene : Research Funding; Onyx: Research Funding; prognostication of MM based on genetic categorization of the disease: Prognostication of MM based on genetic categorization of the disease, Prognostication of MM based on genetic categorization of the disease Patents & Royalties. Dhodapkar:Celgene: Research Funding; KHK: Research Funding.