Kumar, Shaji

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.

Introduction: The utility of amyloidosis staging systems has been validated for newly diagnosed patients, but their role in restaging after starting treatment has not been explored. Given the high early mortality in this disease, restaging remote from the diagnosis may have clinical value. We designed this study to evaluate whether the currently used staging systems are prognostic when applied at 3 and 6 months from starting first-line treatment, and whether stage migration impacts survival. Methods: This is a retrospective study including patients with systemic light chain amyloidosis diagnosed between January, 1st 2006 and June, 30th 2019 and were seen in Mayo Clinic, Rochester, MN within 90 days of diagnosis; the analysis included 535 and 301 patients who had restaging data available for at least one of the staging systems at 3 and 6 months, respectively. Patients were grouped into 4 stages using the 2015 European modification of the Mayo 2004 staging system based on values of cardiac biomarkers (cardiac troponin T and NTproBNP), and using the Mayo 2012 staging system based on cardiac biomarkers and the difference in serum free light chain concentration (dFLC). Overall survival (OS) was calculated from the time of re-staging until death or last follow up. Results: Using the modified Mayo 2004 staging system at 3 months from starting first-line treatment, median OS was 11.8 [95%CI: 11.4-not reached (NR)], 10.8 (95%CI: 9.4-NR), 4.6 (95%CI: 2.8-6.7), and 1.1 (95%CI: 0.7-2.6) years in patients with stage I, II, IIIa, and IIIb, respectively. Using Mayo 2012 staging at 3 months, OS was 11.8 (95%CI: 10.9-NR), 9.0 (95%CI: 6.2-NR), 5.2 (95%CI: 3.3-6.1), and 0.8 (95%CI: 0.7-1.1) years in patients with stage I, II, III, and IV, respectively (Figure 1a &b). Using the modified Mayo 2004 staging system at 6 months from starting first-line treatment, median OS was NR (95%CI: NR-NR), 9.8 (95%CI: 6.2-NR), 5.4 (95%CI: 3.2-9.0) and 0.9 (95%CI: 0.6-3.7) years in patients with stage I, II, IIIa, and IIIb, respectively. Using Mayo 2012 staging at 6 months, OS was NR (95%CI: 8.4-NR), NR (95%CI: 7.9-NR), 4.6 (95%CI: 3.0-6.5), and 0.9 (95%CI: 0.2-1.8) years in patients with stage I, II, III, and IV, respectively (Figure 1c &d). On multivariate analysis, advanced (stage > 2) modified Mayo 2004 stage (HR: 1.6, P=0.004) and advanced (stage > 2) Mayo 2012 stage (HR: 2.4, P<0.001) at 3 months were associated with decreased survival independent of cardiac response, hematologic response, and transplantation status. Although advanced Mayo 2004 stage at 6 months was associated with decreased survival, it was not statistically significant (HR: 1.5, P=0.09). In contrast, advanced Mayo 2012 stage at 6 months was independently associated with decreased survival (HR: 2.1, P=0.02). For both systems, worsening stage at 3 months or at 6 months was associated with a worse survival than retaining the original stage. In contrast, improving stage as compared to remaining in same stage was not associated with better survival at 3 or 6 months (Table 1). When the analysis was restricted to patients who had an advanced stage at diagnosis, improving stage at 3 months was associated with longer survival compared to retaining the original stage, with both modified Mayo 2004 (10.8 vs. 3.3 years, P<0.001) and Mayo 2012 (8.1 vs. 2.6 years, P<0.001) staging systems. At 6 months, stage improvement was associated with longer survival than retaining the original stage when the modified Mayo 2004 staging system was used (NR vs. 5.0 years, P=0.02), but it was not statistically significant when the Mayo 2012 staging system was used (5.9 vs. 3.7 years, P=0.12). Conclusion: The modified Mayo 2004 and the Mayo 2012 staging systems have independent prognostic value when used for restaging after 3 and 6 months from initiation of first-line treatment. Migration to a higher stage from diagnosis predicts decreased survival, compared to retaining the same stage. Stage improvement is associated with a better OS in patients with advanced stage at diagnosis. Disclosures Dispenzieri: Alnylam, Intellia, Janssen, Takeda, Pfizer, Prothena, Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Kapoor:GlaxoSmithKline: Research Funding; Sanofi: Consultancy, Research Funding; Janssen: Research Funding; Celgene: Honoraria; Amgen: Research Funding; Takeda: Honoraria, Research Funding; Cellectar: Consultancy. Dingli:Rigel: Consultancy; Millenium: Consultancy; Sanofi-Genzyme: Consultancy; Bristol Myers Squibb: Research Funding; Karyopharm Therapeutics: Research Funding; Janssen: Consultancy; Alexion: Consultancy; Apellis: Consultancy. Lin:Novartis: Consultancy; Celgene: Consultancy, Research Funding; Bluebird Bio: Consultancy, Research Funding; Sorrento: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gamida Cells: Consultancy; Takeda: Research Funding; Merck: Research Funding; Legend BioTech: Consultancy; Juno: Consultancy; Janssen: Consultancy, Research Funding; Vineti: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding. Gertz:Alnylam: Consultancy; NCI SPORE MM: Research Funding; Ionis/Akcea: Consultancy; Amyloidosis Foundation: Research Funding; Celgene: Consultancy; Johnson and Johnson: Speakers Bureau; DAVA oncology: Speakers Bureau; Advisory Board for Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Advisory Board for Proclara: Membership on an entity's Board of Directors or advisory committees; i3Health: Consultancy; Springer Publishing: Patents & Royalties; Prothena: Consultancy; Sanofi: Consultancy; Janssen: Consultancy; Spectrum: Consultancy, Research Funding; Annexon: Consultancy; Appellis: Consultancy; Amgen: Consultancy; Medscape: Consultancy, Speakers Bureau; Physicians Education Resource: Consultancy; Data Safety Monitoring board from Abbvie: Membership on an entity's Board of Directors or advisory committees; International Waldenstrom Foundation: Research Funding. Kumar:Oncopeptides: Consultancy, Other: Independent Review Committee; IRC member; Genecentrix: Consultancy; Cellectar: Other; Genentech/Roche: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Celgene/BMS: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Kite Pharma: Consultancy, Research Funding; MedImmune: Research Funding; Carsgen: Other, Research Funding; Amgen: Consultancy, Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments, Research Funding; Merck: Consultancy, Research Funding; Janssen Oncology: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Takeda: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Karyopharm: Consultancy; AbbVie: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; BMS: Consultancy, Research Funding; Novartis: Research Funding; Adaptive Biotechnologies: Consultancy; Tenebio: Other, Research Funding; Dr. Reddy's Laboratories: Honoraria; Sanofi: Research Funding.

Background: Patients with Waldenström Macroglobulinemia (WM) tend to present at an older age. Frailty, resulting from comorbidities and reduced organ function, poses unique challenges to the management of WM in the elderly. Age above 65 years, is an established unfavorable prognostic factor in WM. However, data specifically pertaining to the very elderly patient population are scant. The impact of advanced age (≥75 years at diagnosis) on the clinical features and outcomes of patients with symptomatic/active WM were studied. Methods: Patients with active WM, evaluated at Mayo Clinic, Rochester between January 1996 and December 2018 were included in the study. The characteristics and laboratory parameters at presentation of the cohort of patients with the age ≥75 years were compared to those of the younger (age <75 years) cohort. The median follow-up and overall survival (OS) were assessed from active disease to last follow-up or death using the Kaplan Meier method. Because older age is a confounding factor for deaths from unrelated causes, the cause-specific survival (CSS) was calculated. Deaths were deemed WM-related if patients died from progressive disease, transformation with antecedent WM, concomitant light chain (AL) amyloidosis, infection associated with WM or anti-WM therapy related toxicity, while patients who died from other causes were considered to have a WM-unrelated death. The patients who died from causes unrelated to WM were censored at death for CSS analysis. The OS of the cohort of the very elderly patients was compared to that of a cohort of the general US population, matched for age, sex as well as follow-up from the calendar-year of diagnosis, to assess the degree to which WM impacts survival. Results: Among 949 consecutive patients, with a median follow-up of 8.4 years [95% Confidence Interval (CI): 7.7-9.3 years] from active disease, the median age at diagnosis was 65 years (range: 31-93 years). Of 177 patients (19%) who were ≥75 years of age at the onset of active WM, 173 (98%) received anti-WM therapy. The baseline characteristics of the 2 cohorts (patients ≥75 years of age versus <75 years) are outlined in Table 1. The patients in the age ≥75 years cohort were noted to have lower IgM levels and serum albumin, and higher serum LDH and serum β-2 microglobulin compared to the age <75 years cohort. A higher proportion of patients in the age <75 years cohort had coexisting AL amyloidosis at diagnosis. The frequency of MYD88L265P mutation was similar between the 2 cohorts (p=0.2). During the 23-year period, there was an increase in the proportion of patients ≥75 years who were diagnosed with active WM (12% during the 1996-2003 period, 18% during 2004-2010, 25% during 2011-2018; P<0.0001). In the elderly WM cohort, the most frequently used frontline treatment was rituximab monotherapy (36%), followed by rituximab-alkylating agent-based regimen (31%). Of 177 patients with age ≥75 years, 89 (50%) patients were deceased at the time of last follow-up and 58% (52/89) of all deaths in age ≥75 years were attributable to WM. By contrast, 303 (39%) out of the 772 patients in the age <75 years cohort were deceased at last follow-up, with 73% (224/303) deaths attributable to WM. The CSS for patients with age ≥75 years was 10.9 years (95% CI: 7.3-11.7 years) versus 14.7 years (95% CI: 13.2-15.7 years) for age <75 years [Risk ratio 2.1(95% CI: 1.5-2.8); p<0.0001]. At the 1 and 2 year follow-up, WM-related mortality was 6.8% and 11.9%, respectively, for patients with age ≥75 years versus 2.6% and 4.9%, respectively, for the younger cohort. The median OS of patients with age ≥75 years from the diagnosis of active WM was 5.9 years (95% CI: 4.2-7.3 years) compared to the OS of 8.3 years for an age, sex and calendar-year-matched cohort, derived from the general US population (p<0.001), Figure 1. Conclusion: Patients who are ≥75 years of age at the time of diagnosis of active WM present with certain poor prognostic features, including higher serum LDH and β-2 microglobulin and lower serum albumin compared to their younger counterparts. The impact of advanced age is underscored by a poorer WM-specific survival for the subset of patients with the age ≥75 years compared to the younger cohort. Furthermore, although active/symptomatic WM is typically an indolent malignancy, it adversely affects OS of the very elderly patients as suggested by the comparison with an age, sex and calendar-year matched cohort of the general US population. Disclosures Ansell: Bristol Myers Squibb: Research Funding; Trillium: Research Funding; Affimed: Research Funding; Regeneron: Research Funding; ADC Therapeutics: Research Funding; Seattle Genetics: Research Funding; AI Therapeutics: Research Funding; Takeda: Research Funding. Gertz:Ionis/Akcea: Other: personal fee; Alnylam: Other: personal fee; Prothena: Other: personal fee; Spectrum: Other: personal fee, Research Funding; Annexon: Other: personal fee; Appellis: Other: personal fee; Amgen: Other: personal fee; Medscape: Other: personal fee, Speakers Bureau; Physicians Education Resource: Other: personal fee; Abbvie: Other; Celgene: Other; Research to Practice: Other; Sanofi: Other; Teva: Speakers Bureau; Johnson and Johnson: Speakers Bureau; DAVA oncology: Speakers Bureau; Proclara: Other; Springer Publishing: Patents & Royalties; Aurora Bio: Other; Janssen: Other: personal fee. Nowakowski:NanoString: Research Funding; Seattle Genetics: Consultancy; Curis: Consultancy; Kymera: Consultancy; Kite: Consultancy; Ryvu: Consultancy, Membership on an entity's Board of Directors or advisory committees; MorphoSys: Consultancy, Research Funding; Celgene/BMS: Consultancy, Research Funding. Witzig:Spectrum: Consultancy; Immune Design: Research Funding; Karyopharm Therapeutics: Research Funding; Acerta: Research Funding; Incyte: Consultancy; MorphSys: Consultancy; AbbVie: Consultancy; Celgene: Consultancy, Research Funding. Dispenzieri:Pfizer: Research Funding; Janssen: Research Funding; Intellia: Research Funding; Alnylam: Research Funding; Takeda: Research Funding; Celgene: Research Funding. Dingli:Sanofi-Genzyme: Consultancy; Janssen: Consultancy; Bristol Myers Squibb: Research Funding; Rigel: Consultancy; Apellis: Consultancy; Karyopharm Therapeutics: Research Funding; Alexion: Consultancy; Millenium: Consultancy. Kumar:Sanofi: Research Funding; Kite Pharma: Consultancy, Research Funding; Cellectar: Other; Genecentrix: Consultancy; Novartis: Research Funding; Karyopharm: Consultancy; 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; Takeda: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Carsgen: Other, Research Funding; Oncopeptides: Consultancy, Other: Independent Review Committee; IRC member; Genentech/Roche: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Merck: Consultancy, Research Funding; MedImmune: Research Funding; Adaptive Biotechnologies: Consultancy; Tenebio: Other, Research Funding; Dr. Reddy's Laboratories: Honoraria; BMS: Consultancy, Research Funding; Janssen Oncology: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Celgene/BMS: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments. Kapoor:Cellectar: Consultancy; Janssen: Research Funding; Sanofi: Consultancy, Research Funding; Amgen: Research Funding; Takeda: Honoraria, Research Funding; GlaxoSmithKline: Research Funding; Celgene: Honoraria.

CT053 comprises autologous T cells genetically modified with a second-generation chimeric antigen receptor (CAR) incorporating a fully human B-cell maturation antigen (BCMA)-specific single-chain fragment variant (25C2) with high binding affinity. Twenty-four subjects have been treated in phase 1 studies with an 87.5% overall response rate (ORR), 79.2% complete response (CR), and a median duration of response of 21.8 months without inducing immunogenicity [Blood (2019) 134 (Supplement_1): 4435]. Here we present the ongoing phase 1b/2 study (LUMMICAR-2) conducted in North America (NCT03915184) to evaluate safety and clinical efficacy. Eligible subjects with relapsed/refractory multiple myeloma (RRMM) had received ≥3 prior lines of therapy including a proteasome inhibitor (PI), an immunomodulatory drug (IMiD), and an anti-CD38 antibody, and had measurable disease per International Myeloma Working Group (IMWG) criteria. All subjects received a lymphodepletion regimen of cyclophosphamide (500 mg/m2/day ×2 days) and fludarabine (25 mg/m2/ day × 3 days). A single infusion of CT053 at the targeted 1.5-3.0×108 CAR+ T-cell dose was administered after lymphodepletion. Primary objectives for phase 1b were to evaluate the safety and tolerability of CT053 and to identify the recommended phase 2 dose. Adverse events (AEs) were graded using CTCAE, v5.0; cytokine release syndrome (CRS) and neurotoxicity were graded according to ASTCT CRS consensus grading system (Lee DW et al, 2019). The response was assessed per 2016 IMWG criteria, and minimal residual disease (MRD) was assessed by next generation flow cytometry or sequencing. As of July 28, 2020, 20 subjects have enrolled, and 14 subjects have received CT053 infusion in the phase 1b portion of the study, including 8 subjects who received 1.5-1.8×108 CAR+ T cells while 6 subjects received 2.5-3.0×108 CAR+ T cells. The treated subjects had a median age of 59 years (range 42-73), had received a median of 6 (range 3-11) prior lines of treatment, 93% were triple refractory to a PI, IMiD, and anti-CD38 antibody, and 64% were penta-refractory. In addition, 36% of the subjects had extramedullary disease at baseline, and 64% had high-risk cytogenetics. All subjects received bridging therapy. The most common ≥ grade 3 AE was hematological toxicity. All subjects experienced ≥ grade 3 neutropenia (100%) and leukopenia (100%), and 36% of subjects had ≥ grade 3 thrombocytopenia within 30 days of treatment. No grade 3 or higher CRS or neurotoxicity was observed. Twelve of 14 subjects (86%) experienced grade 1 or 2 CRS, including 2 subjects who experienced grade 2 CRS and 1 subject who had grade 2 neurotoxicity. CRS events had a generally predictable time to onset, occurring at a median of 2 days post infusion with a median duration of 4 days (range 1-6). Two subjects received tocilizumab, and one subject with grade 2 CRS received both tocilizumab and steroids. One subject experienced grade 2 neurotoxicity with complete resolution within 24 hours upon administration of dexamethasone. At the data cutoff, 10 subjects were evaluable for at least two months of efficacy assessment with a median follow-up of 4.5 months (range 2-8). A 100% ORR was observed, with 2 stringent complete responses, 2 CRs, 1 very good partial response, and 5 partial responses. Of the 12 subjects with evaluable bone marrow samples, 11 were MRD-negative at the 10-5 sensitivity level. Responses were independent of baseline bone marrow BCMA expression. CT053 transgene levels showed expansion and persistence in peripheral blood, with peak expansion at 7-14 days after infusion. All subjects showed similar kinetics of rapid declines in serum free light chains and soluble BCMA (sBCMA) levels within 1 month, and continued depletion in sBCMA suggests CT053-mediated pharmacodynamic activity. Serum C-reactive protein and cytokine levels (i.e., IL-6, IFNγ, IL-8, IL-10) increased post-infusion within 7 days and correlated with the onset of CRS symptoms. Collectively, these results demonstrate that CT053 at a target dose of 1.5-3.0×108 CAR+ T cells delivers early and deep responses, including MRD negativity, with an acceptable safety profile in subjects with heavily pretreated relapsed or refractory MM. The promising results from the ongoing LUMMICAR-2 study are consistent with the previous phase 1 studies and support the launch of a pivotal Phase 2 LUMMICAR-2 study. Updated results will be presented at the conference. Disclosures Kumar: Carsgen: Other, Research Funding; Kite Pharma: Consultancy, Research Funding; Oncopeptides: Consultancy, Other: Independent Review Committee; IRC member; 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; Adaptive Biotechnologies: Consultancy; Janssen Oncology: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Dr. Reddy's Laboratories: Honoraria; Tenebio: Other, Research Funding; Genecentrix: Consultancy; BMS: Consultancy, Research Funding; AbbVie: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Amgen: Consultancy, Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments, Research Funding; MedImmune: Research Funding; Cellectar: Other; Merck: Consultancy, Research Funding; Takeda: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Sanofi: Research Funding; Novartis: Research Funding; Karyopharm: Consultancy. Baz:Sanofi, Karypharm, Janssen, Celgene: Other: Advisory board; Karyopharm, janssen, Bristol Myers Squibb, Celgene, Merck, Sanofi, Abbvie Inc.: Research Funding. Orlowski:Amgen, Inc., AstraZeneca, BMS, Celgene, EcoR1 Capital LLC, Forma Therapeutics, Genzyme, GSK Biologicals, Ionis Pharmaceuticals, Inc., Janssen Biotech, Juno Therapeutics, Kite Pharma, Legend Biotech USA, Molecular Partners, Regeneron Pharmaceuticals, Inc.,: Honoraria, Membership on an entity's Board of Directors or advisory committees; Founder of Asylia Therapeutics, Inc., with associated patents and an equity interest, though this technology does not bear on the current submission.: Current equity holder in private company, Patents & Royalties; STATinMED Research: Consultancy; Sanofi-Aventis, Servier, Takeda Pharmaceuticals North America, Inc.: Honoraria, Membership on an entity's Board of Directors or advisory committees; Laboratory research funding from BioTheryX, and clinical research funding from CARsgen Therapeutics, Celgene, Exelixis, Janssen Biotech, Sanofi-Aventis, Takeda Pharmaceuticals North America, Inc.: Research Funding. Anderson:Amgen: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; GSK: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Karyopharm: Consultancy, Honoraria, Research Funding. Ma:CARsgen Therapeutics Corp.: Current Employment. Bilgi:CARsgen Therapeutics Corp.: Other: Current shareholder in the company. Kansagra:Alnylam Pharmaceuticals, Bristol Myers Squibb /Celgene, GlaxoSmithKline, Janssen, Pharmacyclics, Takeda Pharmaceuticals, Pfizer, Karyopharm Therpeutics: Other: Advisory Board. Kapoor:Janssen: Research Funding; Cellectar: Consultancy; Takeda: Honoraria, Research Funding; GlaxoSmithKline: Research Funding; Celgene: Honoraria; Amgen: Research Funding; Sanofi: Consultancy, Research Funding. Li:CARsgen Therapeutics Co. LtD: Current Employment, Current equity holder in private company. Brayer:Bristol-Myers Squibb, WindMIL Therapeutics: Research Funding; Janssen: Consultancy; Bristol-Myers Squibb, Janssen, Amgen: Speakers Bureau.

Abstract Chromosome region maintenance protein 1 (CRM1) mediates protein export from the nucleus and is a new target for anticancer therapeutics. Broader application of KPT-330 (selinexor), a first-in-class CRM1 inhibitor recently approved for relapsed multiple myeloma and diffuse large B-cell lymphoma, have been limited by substantial toxicity. We discovered that salicylates markedly enhance the antitumor activity of CRM1 inhibitors by extending the mechanisms of action beyond CRM1 inhibition. Using salicylates in combination enables targeting of a range of blood cancers with a much lower dose of selinexor, thereby potentially mitigating prohibitive clinical adverse effects. Choline salicylate (CS) with low-dose KPT-330 (K+CS) had potent, broad activity across high-risk hematological malignancies and solid-organ cancers ex vivo and in vivo. The K+CS combination was not toxic to nonmalignant cells as compared with malignant cells and was safe without inducing toxicity to normal organs in mice. Mechanistically, compared with KPT-330 alone, K+CS suppresses the expression of CRM1, Rad51, and thymidylate synthase proteins, leading to more efficient inhibition of CRM1-mediated nuclear export, impairment of DNA-damage repair, reduced pyrimidine synthesis, cell-cycle arrest in S-phase, and cell apoptosis. Moreover, the addition of poly (ADP-ribose) polymerase inhibitors further potentiates the K+CS antitumor effect. K+CS represents a new class of therapy for multiple types of blood cancers and will stimulate future investigations to exploit DNA-damage repair and nucleocytoplasmic transport for cancer therapy in general.

AbstractWe studied 2,528 patients with upfront autologous haematopoietic cell transplantation (AHCT) for multiple myeloma (MM) from 2008–2017 to develop a prognostic model to predict outcomes. High‐risk cytogenetics included t(4;14), t(14;16), t(14;20), del13q on karyotype, del17p, +1q or 1pdel. A Cox model identified factors prognostic of progression/relapse in a training subset (n = 1,246). A weighted score using these factors was assigned to a validation cohort (n = 774). Presence of high‐risk cytogenetics [hazard ratio, (HR) 1·68 (1·3–2·17)] and pre‐AHCT bone marrow plasma cells (BMPCs) ≥10% [1·68 (1·33–2·12)] were assigned 4 points each; albumin at diagnosis <3·5 g/dl [1·31 (1·07–1·61)] 2; standard risk cytogenetics 1, and no cytogenetics abnormality, BMPCs <10% at AHCT and albumin ≥3·5 g/dl at diagnosis 0 points each. A three‐category system with low risk (0–3), intermediate risk (4–8) and high risk (9–10) showed 3‐year progression‐free survival in the low vs. intermediate vs. high risk of 58% (95% CI: 52–63) vs. 49% (95% CI: 43–56) vs. 31% (95% CI: 12–51), P < 0.001 respectively, and 3‐year OS in low vs. intermediate vs. high risk of 88% (95% CI: 84–91) vs. 81% (95% CI: 76–86) vs. 64% (95% CI: 39–80); P < 0·001. Our prognostic scoring system can identify MM patients at risk for early relapse after AHCT.

Abstract BackgroundOverexpression of c-Myc is required for the progression of pre-malignant plasma cells in monoclonal gammopathy of undetermined significance (MGUS) to malignant plasma cells in multiple myeloma (MM). c-Myc also increases glutamine anaplerosis into the tricarboxylic acid (TCA) cycle within cancer cells. Whether increased glutamine anaplerosis is associated with the progression of pre-malignant to malignant plasma cells is unknown.MethodsHuman volunteers (N = 7) and patients with MGUS (N = 11) and MM (N = 12) were prospectively recruited to undergo an intravenous infusion of 13C-labelled glutamine followed by a bone marrow aspiration to obtain bone marrow cells and plasma.ResultsDespite notable heterogeneity, stable isotope resolved metabolomics (SIRM) revealed that the mean 13C-labelled glutamine anaplerosis into the TCA cycle was higher in malignant compared to pre-malignant bone marrow plasma cells relative to the remainder of their paired bone marrow mononuclear cells. RNA sequencing demonstrated a higher relative mRNA expression of c-Myc and glutamine transporters such as ASCT2 and SN2 in malignant compared to pre-malignant bone marrow plasma cells. Finally, higher quantitative levels of TCA cycle intermediates in the bone marrow plasma differentiated MM from MGUS patients.ConclusionMeasurement of the in vivo activity of glutamine anaplerosis into the TCA cycle provides novel insight into the metabolic changes associated with the transformation of pre-malignant plasma cells in MGUS to malignant plasma cells in MM.

Abstract Gastrointestinal complications of multiple myeloma (MM) treatment are common and include nausea, constipation, and diarrhea. However, acute gastrointestinal events like perforations are rare. We aimed to describe the characteristics and outcomes of patients with MM that had colonic perforations during their treatment. This is a retrospective study that included patients from all three Mayo Clinic sites who had MM and developed a colonic perforation. All patients were diagnosed with colonic perforations based on CT scans and were surgically treated. Patients diagnosed with AL amyloidosis, a perforated colon complicating neutropenic colitis during ASCT and those with perforation due to colonic cancer were excluded. A high dose of dexamethasone was defined as ≥40 mg dexamethasone once a week. Thirty patients met inclusion criteria. All patients received steroids at doses ≥10 mg once weekly prior to the perforation, while four (11%) were on high‐dose dexamethasone without chemotherapy. Fourteen patients were given high doses of dexamethasone. Twenty‐five patients required ostomies with all surviving surgery. Twenty‐four perforations (80%) were associated with diverticulitis. Treatment with steroids was resumed in 23 patients with no further gastrointestinal complications. The median OS was 20 months following perforation (IQR 8–59). Within the same timeframe 5854 patients were treated at Mayo Clinic for MM, making the risk of bowel perforation 0.5%. Intestinal perforations in MM are rare and, in our series, always occurred with dexamethasone ≥10 mg per week. Urgent surgery is lifesaving and resumption of anti‐myeloma treatment appears to be safe.