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Standard-of-care treatment for patients with newly diagnosed multiple myeloma is bortezomib-based induction followed by high-dose melphalan and autologous haematopoietic stem-cell transplantation (HSCT) and lenalidomide maintenance. We aimed to evaluate whether an immunomodulatory-free carfilzomib-based induction, consolidation, and maintenance protocol without autologous HSCT was non-inferior to the same induction regimen followed by autologous HSCT and maintenance.CARDAMON is a randomised, open-label, phase 2 trial in 19 hospitals in England and Wales, UK. Newly diagnosed, transplantation-eligible patients with multiple myeloma aged 18 years or older with an Eastern Cooperative Oncology Group (ECOG) performance status of 0-2 received four 28-day cycles of carfilzomib (56 mg/mBetween June 16, 2015, and July 8, 2019, 281 patients were enrolled, with 218 proceeding to randomisation (109 assigned to the KCd consolidation group [99 of whom completed consolidation] and 109 to the HSCT group [104 of whom underwent transplantation]). A further seven patients withdrew before initiation of carfilzomib maintenance (two in the KCd consolidation group vs five in the HSCT group). Median age was 59 years (IQR 52 to 64); 166 (59%) of 281 patients were male and 115 (41%) were female. 152 (71%) of 214 patients with known ethnicity were White, 37 (17%) were Black, 18 (8%) were Asian, 5 (2%) identified as Mixed, and 2 (1%) identified as other. Median follow-up from randomisation was 40·2 months (IQR 32·7 to 51·8). After induction, 162 (57·7%; 95% CI 51·6 to 63·5) of 281 patients had at least a very good partial response. The 2-year progression-free survival was 75% (95% CI 65 to 82) in the HSCT group versus 68% (95% CI 58 to 76) in the KCd group (difference -7·2%, 70% CI -11·1 to -2·8), exceeding the non-inferiority margin. The most common grade 3-4 events during KCd induction and consolidation were lymphocytopenia (72 [26%] of 278 patients who started induction; 15 [14%] of 109 patients who started consolidation) and infection (50 [18%] of 278 for induction; 15 [14%] of 109 for consolidation), and during carfilzomib maintenance were hypertension (20 [21%] of 97 patients in the KCd consolidation group vs 23 [23%] of 99 patients in the HSCT group) and infection (16 [16%] of 97 patients vs 25 [25%] of 99). Treatment-related serious adverse events at any point during the trial were reported in 109 (39%) of 278 patients who started induction, with infections (80 [29%]) being the most common. Treatment-emergent deaths were reported in five (2%) of 278 patients during induction (three from infection, one from cardiac event, and one from renal failure) and one of 99 patients during maintenance after autologous HSCT (oesophageal carcinoma).KCd did not meet the criteria for non-inferiority compared with autologous HSCT, but the marginal difference in progression-free survival suggests that further studies are warranted to explore deferred autologous HSCT in some subgroups, such as individuals who are MRD negative after induction.Cancer Research UK and Amgen.

Precision medicine holds great promise to improve outcomes in cancer, including haematological malignancies. However, there are few biomarkers that influence choice of chemotherapy in clinical practice. In particular, multiple myeloma requires an individualized approach as there exist several active therapies, but little agreement on how and when they should be used and combined. We have previously shown that a transcriptomic signature can identify specific bortezomib- and lenalidomide-sensitivity. However, gene expression signatures are challenging to implement clinically. We reasoned that signatures based on the presence or absence of gene mutations would be more tractable in the clinical setting, though examples of such signatures are rare. We performed whole exome sequencing as part of the CARDAMON trial, which employed carfilzomib-based therapy. We applied advanced machine learning approaches to discover mutational patterns predictive of treatment outcome. The resulting model accurately predicted progression-free survival (PFS) both in CARDAMON patients and in an external validation set of patients from the CoMMpass study who had received carfilzomib. The signature was specific for carfilzomib therapy and was strongly driven by genes on chromosome 1p36. Importantly, patients predicted to be carfilzomib-sensitive had a longer PFS when treated with carfilzomib/lenalidomide/dexamethasone than with bortezomib/carfilzomib/dexamethasone. However, in those predicted to be carfilzomib-insensitive, the latter therapy may have been capable of eradicating carfilzomib-resistant clones. We propose that the signature can be used to make rational therapeutic decisions and could be incorporated into future clinical trials.

Purpose:Immune dysregulation is described in multiple myeloma. While preclinical models suggest a role for altered T-cell immunity in disease progression, the contribution of immune dysfunction to clinical outcomes remains unclear. We aimed to characterize marrow-infiltrating T cells in newly diagnosed patients and explore associations with outcomes of first-line therapy.Experimental Design:We undertook detailed characterization of T cells from bone marrow (BM) samples, focusing on immune checkpoints and features of immune dysfunction, correlating with clinical features and progression-free survival.Results:We found that patients with multiple myeloma had greater abundance of BM regulatory T cells (Tregs) which, in turn, expressed higher levels of the activation marker CD25 compared with healthy donors. Patients with higher frequencies of Tregs had shorter PFS and a distinct Treg immune checkpoint profile (increased PD-1, LAG-3) compared with patients with lower frequencies of Tregs. Analysis of CD4 and CD8 effectors revealed that low CD4effector (CD4eff):Treg ratio and increased frequency of PD-1–expressing CD4eff cells were independent predictors of early relapse over and above conventional risk factors, such as genetic risk and depth of response. Ex vivo functional analysis and RNA sequencing revealed that CD4 and CD8 cells from patients with greater abundance of CD4effPD-1+ cells displayed transcriptional and secretory features of dysfunction.Conclusions:BM-infiltrating T-cell subsets, specifically Tregs and PD-1–expressing CD4 effectors, negatively influence clinical outcomes in newly diagnosed patients. Pending confirmation in larger cohorts and further mechanistic work, these immune parameters may inform new risk models, and present potential targets for immunotherapeutic strategies.

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PURPOSE Smoldering multiple myeloma (SMM) is a precursor condition of multiple myeloma (MM) with a 10% annual risk of progression. Various prognostic models exist for risk stratification; however, those are based on solely clinical metrics. The discovery of genomic alterations that underlie disease progression to MM could improve current risk models. METHODS We used next-generation sequencing to study 214 patients with SMM. We performed whole-exome sequencing on 166 tumors, including 5 with serial samples, and deep targeted sequencing on 48 tumors. RESULTS We observed that most of the genetic alterations necessary for progression have already been acquired by the diagnosis of SMM. Particularly, we found that alterations of the mitogen-activated protein kinase pathway ( KRAS and NRAS single nucleotide variants [SNVs]), the DNA repair pathway (deletion 17p, TP53, and ATM SNVs), and MYC (translocations or copy number variations) were all independent risk factors of progression after accounting for clinical risk staging. We validated these findings in an external SMM cohort by showing that patients who have any of these three features have a higher risk of progressing to MM. Moreover, APOBEC associated mutations were enriched in patients who progressed and were associated with a shorter time to progression in our cohort. CONCLUSION SMM is a genetically mature entity whereby most driver genetic alterations have already occurred, which suggests the existence of a right-skewed model of genetic evolution from monoclonal gammopathy of undetermined significance to MM. We identified and externally validated genomic predictors of progression that could distinguish patients at high risk of progression to MM and, thus, improve on the precision of current clinical models.

Purpose: Immune dysregulation is described in multiple myeloma. While preclinical models suggest a role for altered T-cell immunity in disease progression, the contribution of immune dysfunction to clinical outcomes remains unclear. We aimed to characterize marrow-infiltrating T cells in newly diagnosed patients and explore associations with outcomes of first-line therapy. Experimental Design: We undertook detailed characterization of T cells from bone marrow (BM) samples, focusing on immune checkpoints and features of immune dysfunction, correlating with clinical features and progression-free survival. Results: We found that patients with multiple myeloma had greater abundance of BM regulatory T cells (Tregs) which, in turn, expressed higher levels of the activation marker CD25 compared with healthy donors. Patients with higher frequencies of Tregs had shorter PFS and a distinct Treg immune checkpoint profile (increased PD-1, LAG-3) compared with patients with lower frequencies of Tregs. Analysis of CD4 and CD8 effectors revealed that low CD4effector (CD4eff):Treg ratio and increased frequency of PD-1–expressing CD4eff cells were independent predictors of early relapse over and above conventional risk factors, such as genetic risk and depth of response. Ex vivo functional analysis and RNA sequencing revealed that CD4 and CD8 cells from patients with greater abundance of CD4effPD-1+ cells displayed transcriptional and secretory features of dysfunction. Conclusions: BM-infiltrating T-cell subsets, specifically Tregs and PD-1–expressing CD4 effectors, negatively influence clinical outcomes in newly diagnosed patients. Pending confirmation in larger cohorts and further mechanistic work, these immune parameters may inform new risk models, and present potential targets for immunotherapeutic strategies.

Patients with multiple myeloma (MM), an incurable malignancy of plasma cells, frequently develop osteolytic bone lesions. In this study, glycosphingolipids were essential in promoting autophagic degradation of the signaling molecule TRAF3, a key step in bone-resorbing osteoclast differentiation. Specifically altering the glycosphingolipid composition with eliglustat, an FDA approved glucosylceramide synthase inhibitor, arrested osteoclast differentiation; this could be rescued by exogenous addition of the missing glycosphingolipids. Eliglustat significantly reduced bone disease in several preclinical models of MM by inhibiting osteoclastogenesis and, due to its unique mode of action, it was able to act in combination with existing bone protective drugs. Furthermore, eliglustat arrested osteoclast differentiation from the bone marrow of MM patients in a glycosphingolipid-dependent way. This work identifies both the mechanism by which glucosylceramide synthase inhibition blocks autophagic degradation of TRAF3 to reduce osteoclastogenesis as well as highlighting the translational potential of eliglustat to be combined with current treatments.

Smoldering multiple myeloma (SMM) is a precursor condition of multiple myeloma (MM) with significant heterogeneity in disease progression. Existing clinical models of progression risk do not fully capture this heterogeneity. Here we integrate 42 genetic alterations from 214 SMM patients using unsupervised binary matrix factorization (BMF) clustering and identify six distinct genetic subtypes. These subtypes are differentially associated with established MM-related RNA signatures, oncogenic and immune transcriptional profiles, and evolving clinical biomarkers. Three genetic subtypes are associated with increased risk of progression to active MM in both the primary and validation cohorts, indicating they can be used to better predict high and low-risk patients within the currently used clinical risk stratification models.

Proteasome inhibitors have been associated with thrombotic microangiopathy (TMA) - a group of disorders characterised by occlusive microvascular thrombosis causing microangiopathic haemolytic anaemia, thrombocytopenia and end-organ damage. To date, carfilzomib-associated TMA has predominantly been described in relapsed/refractory myeloma patients. We report eight patients with newly diagnosed myeloma who experienced TMA events while receiving carfilzomib on the phase II CARDAMON trial. The first three occurred during maintenance single-agent carfilzomib, two occurred at induction with carfilzomib given with cyclophosphamide and dexamethasone (KCd) and three occurred during KCd consolidation. At TMA presentation 6/8 were hypertensive; 7/8 had acute kidney injury and in three, renal impairment persisted after resolution of TMA in other respects. The mechanism of carfilzomib-associated TMA remains unclear, though patients with known hypertension seem particularly susceptible. Given the first three cases occurred during maintenance after a longer than five-week treatment break, a protocol amendment was instituted with: aggressive hypertension management, carfilzomib step-up dosing (20 mg/m2 on day 1) at start of maintenance before dose escalation to 56 mg/m2 maximum, and adding 10 mg dexamethasone as premedication to maintenance carfilzomib infusions. No further TMA events occurred during maintenance following this amendment and the TMA incidence reduced from 4·2 to 1·6 per 1 000 patient cycles.

Routine use of novel agents to treat newly diagnosed and relapsed multiple myeloma (MM) produces high response rates and improved survival. However, 15–20% of patients have suboptimal responses and their management remains challenging.1 Traditional regimens, such as DT‐PACE (dexamethasone, thalidomide, cisplatin, doxorubicin, cyclophosphamide, etoposide) and ESHAP (etoposide, methylprednisolone, cytarabine, cisplatin) are employed in patients with relapsed/refractory (RR) disease, and may bridge patients to autologous stem cell transplantation (ASCT).2-4 Originally developed to improve responses to traditional chemotherapy regimens, and enable stem cell mobilization,5-7 the role of infusional regimens in the context of novel agents is unclear, especially as recently reported series indicate relatively poor outcomes.8, 9 These regimens can be associated with significant toxicity,2 placing a burden on healthcare resources.10 We undertook a single‐centre retrospective analysis to assess the role of infusional regimens in RR MM patients to explore and identify features associated with clinical benefit. Relevant clinical information was obtained from electronic records. Overall response rate (ORR) and cytogenetic risk were assessed as per International Myeloma Working Group (IMWG) criteria (Table I).11 [Progression‐free (PFS) and overall survival (OS) were estimated using Kaplan–Meier and Cox regression methods (time‐dependent where appropriate)].

Haematology patients receiving chemo- or immunotherapy are considered to be at greater risk of COVID-19-related morbidity and mortality. We aimed to identify risk factors for COVID-19 severity and assess outcomes in patients where COVID-19 complicated the treatment of their haematological disorder. A retrospective cohort study was conducted in 55 patients with haematological disorders and COVID-19, including 52 with malignancy, two with bone marrow failure and one immune-mediated thrombotic thrombocytopenic purpura (TTP). COVID-19 diagnosis coincided with a new diagnosis of a haematological malignancy in four patients. Among patients, 82% were on systemic anti-cancer therapy (SACT) at the time of COVID-19 diagnosis. Of hospitalised patients, 37% (19/51) died while all four outpatients recovered. Risk factors for severe disease or mortality were similar to those in other published cohorts. Raised C-reactive protein at diagnosis predicted an aggressive clinical course. The majority of patients recovered from COVID-19, despite receiving recent SACT. This suggests that SACT, where urgent, should be administered despite intercurrent COVID-19 infection, which should be managed according to standard pathways. Delay or modification of therapy should be considered on an individual basis. Long-term follow-up studies in larger patient cohorts are required to assess the efficacy of treatment strategies employed during the pandemic.

Background Plasma cell disorders (PCD) are at risk of inadequate immune responses to COVID-19 vaccines due to recognised humoral and cellular immune dysfunction which is multi-factorial and related to host and disease factors. With an estimated risk of 33% mortality from contracting COVID-19 in this population, protection with an anti-SARS-CoV-2 vaccination is critical. Initial extension to vaccination intervals in the United Kingdom to 12 weeks in December 2020 led to concerns that PCD patients would be left vulnerable for an extended period. Methods A clinical audit was performed on measured serological responses in PCD patients after first and second doses of the BNT162b2 and ChAdOx-1 nCoV-19 vaccines. Antibody levels were measured using Elecsys Anti-SARS-CoV-2S assay (Roche) for quantitative detection of IgG Abs, specific for the SARS-CoV-2 spike-protein. Positive cut-off of 0.80 U/mL defined serological response. Testing was performed at (or closest to) 4 and 8-weeks post-dose. Baseline nucleocapsid Ab results were available from previous screening in a subset of patients. All patients on CIT underwent 4-weekly swabs. Clinical information was retrieved from medical records. Results 188 PCD patients (155 multiple myeloma, 18 amyloid, 10 SMM/MGUS, other 5 PCD), median age 64 (range 32-84), had serological assessment after both vaccine doses. Fourteen with previous COVID-19 infection were excluded. Of 174 patients, 112 were tested after first dose. 88% (153) were on chemo-immunotherapy treatment (CIT). Seropositive rate after first dose was 63% (71/112); of those with available negative baseline antibody test, 62% (31/50) seroconverted. After second dose, 89% (154/174) were seropositive; of those with negative baseline antibody, 90% (61/68) seroconverted. Expectedly, paired median titres after second dose were significantly higher than post first dose (n=112, 3.245 U/mL (IQR 0.4-25.55) vs 518 U/mL (IQR 29.40-2187) p=4 lines therapy, light-chain disease, male gender and not responding to first dose were significant factors for not responding to two vaccine doses. We explored =4 lines of treatment were independent predictors of less-than-optimal response (anti-CD38 CIT of borderline significance). Importantly, vaccine dosing intervals classified as =42 days (Figure 1C) or 28 +/- 14 days vs 84 +/- 14 days (excluding n=66 in neither) (Figure 1D) did not show difference in both definitions of response, neither did vaccine type. Fourteen with previous COVID-19 infection responded to one vaccine dose, median titres 2121 U/mL (IQR 23.48-2500)) rising to median 2500 U/mL (IQR 2500-2500) after second dose (Figure 1E), significantly higher than those without previous infection. Conclusion Serological response to COVID-19 vaccine is lower in PCD patients than reported healthy controls at 63% after first dose, rising to 89% after second dose, despite extended dosing intervals. PCD patients should be prioritised for shorter intervals, as we show that patients seronegative after first dose, respond after second dose. Further work in PCD is needed to understand how Ab levels correlate to neutralisation capability, cellular responses, protection from infection and how long seroconversion lasts to better define correlates of protection. A booster vaccination or prophylactic passive antibody strategy may be required for those identified at risk, shown not to have responded to two vaccine doses or to have less-than-optimal response. Results from these trials will be eagerly awaited. References: 1. University of Birmingham. About the OCTAVE Trial 2021 [Available from: https://www.birmingham.ac.uk/research/crctu/trials/octave/patients-and-public/about-octave.aspx. Accessed 1 st August 2021. 2. Avivi I, Balaban R, Shragai T, Sheffer G, Morales M, Aharon A, et al. Humoral response rate and predictors of response to BNT162b2 mRNA COVID19 vaccine in patients with multiple myeloma. Br J Haematol. 2021. Figure 1 Figure 1. Disclosures Wechalekar: Amgen: Research Funding; Alexion, AstraZeneca Rare Disease: Consultancy; Caelum Biosciences: Other: Clinical Trial Funding; Janssen: Consultancy; Takeda: Honoraria; Celgene: Honoraria. Popat: AbbVie, BMS, Janssen, Oncopeptides, and Amgen: Honoraria; Takeda: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; GlaxoSmithKline: Consultancy, Honoraria, Research Funding; Abbvie, Takeda, Janssen, and Celgene: Consultancy; Janssen and BMS: Other: travel expenses. Rabin: BMS / Celgene: Consultancy, Honoraria, Other: Travel support for meetings; Takeda: Consultancy, Honoraria, Other: Travel support for meetings; Janssen: Consultancy, Honoraria, Other: Travel support for meetings. Yong: BMS: Research Funding; Amgen: Honoraria; GSK: Honoraria; Takeda: Honoraria; Janssen: Honoraria, Research Funding; Sanofi: Honoraria, Research Funding; Autolus: Research Funding.

Introduction: Multiple Myeloma (MM) is an incurable plasma cell malignancy commonly preceded by the asymptomatic stage smoldering multiple myeloma (SMM). MM is characterized with significant genomic heterogeneity of chromosomal gains and losses (CNVs), translocations, and point mutations (SNVs); alterations that are also observed in SMM patients. However, current SMM risk models rely solely on clinical markers and do not accurately capture progression risk. While incorporating some genomic biomarkers improves prediction, using all MM genomic features to comprehensively stratify patients may increase risk stratification precision in SMM. Methods: We obtained a total of 214 patient samples at SMM diagnosis. We performed whole-exome sequencing on 166 tumors; of these, RNA sequencing was performed on 100. Targeted capture was done on 48 additional tumors. Upon binarization of DNA features, we performed consensus non-negative matrix factorization to identify distinct molecular clusters. We then trained a random forest classifier on translocations, SNVs, and CNVs. The predicted clinical outcomes for the molecular subtypes were further validated in an independent SMM cohort of 74 patients. Results: We identified six genomic subtypes, four with hyperdiploidy (>48 chromosomes, HMC, HKR, HNT, HNF) and two with IgH translocations (FMD, CND) (Table 1). In multivariate analysis accounting for IMWG (20-2-20) clinical risk stages, high-risk (HMC, FMD, HKR) and intermediate-risk (HNT, HNF) genetic subtypes were independent predictors of progression (Hazards ratio [HR]: 3.8 and 5.5, P = 0.016 and 0.001, respectively). The low-risk, CND subtype harboring translocation (11;14) was enriched for the previously defined CD-2 MM signature defined by the B cell markers CD20 and CD79A (FDR = 0.003 ), showed upregulation of CCND1, E2F1, and E2F7 (FDR = 0.01, 0.0004, 0.08), and was enriched for G2M checkpoint, heme metabolism, and monocyte cell signature (FDR = 0.003, 0.003, 0.003, respectively). The FMD subtype with IgH translocations (4;14) and (14;16) was enriched for P53, mTORC1, unfolded protein signaling pathways and plasmacytoid dendritic cell signatures (FDR = 0.01, 0.005, 0.008, respectively). The HKR tumors were enriched for inflammatory cytokine signaling, MYC target genes, T regulatory cell signature, and the MM proliferative (PR) signatures (FDR = 0.02, 0.03, 0.007, 0.02, respectively). The APOBEC mutational signature was enriched in HMC and FMD tumors (P = 0.005), while there was no statistical difference across subtypes in the AID signature. The median follow-up for the primary cohort is 7.1 years. Median TTP for patients in HMC, FMD, and HKR was 3.8, 2.6, and 2.2 years, respectively; TTP for HNT and HNF was 4.3 and 5.2, respectively, while it was 11 years in CND patients (P = 0.007). Moreover, by analyzing the changes in MM clinical biomarkers over time, we found that patients from high-risk subgroups had higher odds of developing evolving hemoglobin and monoclonal protein levels over time (P = 0.01 and 0.002, respectively); Moreover, the absolute increase in M-protein was significantly higher in patients from the high-risk genetic subtypes at one, two, and five years from diagnosis (P = 0.001, 0.03, and 0,01, respectively). Applying the classifier to the external cohort replicated our findings where intermediate and high-risk genetic subgroups conferred increased risk of progression to MM in multivariate analysis after accounting for IMWG staging (HR: 5.5 and 9.8, P = 0.04 and 0.005, respectively). Interestingly, within the intermediate-risk clinical group in the primary cohort, patients in the high-risk genetic subgroups had increased risk of progression (HR: 5.2, 95% CI 1.5 - 17.3, P = 0.007). In the validation cohort, these patients also had an increased risk of progression to MM (HR: 6.7, 95% CI 1.2 - 38.3, P = 0.03), indicating that molecular classification improves the clinical risk-stratification models. Conclusion: We identified and validated in an independent dataset six SMM molecular subgroups with distinct DNA alterations, transcriptional profiles, dysregulated pathways, and risks of progression to active MM. Our results underscore the importance of molecular classification in addition to clinical evaluation in better identifying high-risk SMM patients. Moreover, these subgroups may be used to identify tumor vulnerabilities and target them with precision medicine efforts. Figure 1 Figure 1. Disclosures Bustoros: Janssen, Bristol Myers Squibb: Honoraria, Speakers Bureau; Takeda: Consultancy, Honoraria. Casneuf: Janssen: Current Employment. Kastritis: Amgen: Consultancy, Honoraria, Research Funding; Takeda: Honoraria; Pfizer: Consultancy, Honoraria, Research Funding; Genesis Pharma: Honoraria; Janssen: Consultancy, Honoraria, Research Funding. Walker: Bristol Myers Squibb: Research Funding; Sanofi: Speakers Bureau. Davies: Takeda: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Janssen: Consultancy, Honoraria. Dimopoulos: Amgen: Honoraria; BMS: Honoraria; Takeda: Honoraria; Beigene: Honoraria; Janssen: Honoraria. Bergsagel: Genetech: Consultancy, Honoraria; Oncopeptides: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Patents & Royalties: human CRBN mouse; GSK: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Yong: BMS: Research Funding; Autolus: Research Funding; Takeda: Honoraria; Janssen: Honoraria, Research Funding; Sanofi: Honoraria, Research Funding; GSK: Honoraria; Amgen: Honoraria. Morgan: BMS: Membership on an entity's Board of Directors or advisory committees; Jansen: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees. Getz: IBM, Pharmacyclics: Research Funding; Scorpion Therapeutics: Consultancy, Current holder of individual stocks in a privately-held company, Membership on an entity's Board of Directors or advisory committees. Ghobrial: AbbVie, Adaptive, Aptitude Health, BMS, Cellectar, Curio Science, Genetch, Janssen, Janssen Central American and Caribbean, Karyopharm, Medscape, Oncopeptides, Sanofi, Takeda, The Binding Site, GNS, GSK: Consultancy.

Background Extensive protein synthesis in multiple myeloma (MM) cells renders them vulnerable to proteasome inhibitors (PI), a cornerstone of anti-myeloma therapy. However, relapse is inevitable and PI resistance remains a major barrier to improving outcomes. Adaptive responses to PI include upregulation of autophagy, another major degradation pathway in cells. We hypothesised that autophagy inhibition increases cell death and impedes recovery of MM cells exposed to Carfilzomib (K), a second generation PI effective in newly diagnosed and relapsed/refractory MM. Methods: Human myeloma cell lines (HMCL) and patient samples were exposed to a 1-hour pulse of K to mimic pharmacokinetics, ± autophagy inhibitors (AI) vacuolar protein sorting kinase 34 inhibitor (VPS34i) or unc-51 like autophagy initiating kinase inhibitor (ULKi). Apoptosis was assessed by Annexin V/Propidium iodide (AnV/PI) flow cytometry (FC) and autophagic flux by western blotting (WB) and FC for light chain 3B (LC3B) ± bafilomycin (B). Cell cycle was examined by FC using KI67/PI. Results: Basal autophagic flux was seen in all HMCL (MM1s, H929, KMS12BM) tested (±B). Autophagic flux increased in response to K: MM1s mean fluorescence intensity (MFI) control (CTL) 318±28 vs K 567±72, (mean±SEM),p=0.01, n=6). Autophagy was inhibited in all 3 HMCL with AI. Combined exposure to K and AI (VPS34i or ULKi) increased time dependent apoptosis in all HMCL tested: MM1s 31±8% (K) vs 58±9% (K+VPS34i), p=0.03, (n=3), and 13±0.4% (K) vs 63±16% (K+ULKi), p=0.03 (n=3), (K 10nM, AI 1uM) 48 hours(h) post K exposure. Basal autophagic flux was detected in all CD138+ primary MM patient samples tested by LC3B FC assay (MFI CTL B- 407±57 vs B+ 1081±125, p K treated MM1s cells were examined for kinetics of ubiquitinated protein build up and autophagic induction by WB. Increased ubiquitinated proteins were detectable up to 24h post K pulse, whilst autophagic flux increased up to 72h but returned to baseline thereafter (n=3). MM1s cells were treated with K±VPS34i for up to 7 days and apoptosis, absolute cell number and cell cycle assessed. In K treated cells, apoptosis was maximal at 72h but declined thereafter. Viable cell numbers fell initially but increased after 96h, indicating cell recovery. However, in MM1s cells treated with K+VPS34i/ULKi, apoptosis was enhanced with a rapid loss of viable cells (Fig 2) and viable cell numbers remained low at all timepoints (Fig 3). Cell cycle assays confirmed persistent G0/G1 arrest in MM1s cells treated with K+VPS34i or ULKi at all timepoints, whilst cell proliferation recovered in K treated cells on day 3, (15±3% cells in S/G2M in K treated cells vs 2±0.4% with K+VPS34i, p=0.02, n=4, 11±3% in S/G2M with K vs 1± 0.7% with K+ULKi, p=0.04, n=3, day 4)(Fig 4). To confirm that effects of AI were mediated via autophagy, KMS28PE (ATG12 null HMCL) were treated with K±VPS34i. These autophagy depleted cells showed limited basal or K induced autophagic flux and addition of VPS34i to K had no effect on apoptosis or cell cycle. Conclusion MM cells displayed active autophagic flux that increased with K treatment. Inhibition of autophagy increased K induced apoptosis, prolonged K-induced cell cycle arrest and prevented MM cell recovery. Addition of AI to K increased cytotoxicity in patient samples and many patients showed sensitivity to AI alone; these effects correlated with basal autophagic flux. These data suggest that autophagy plays a vital role in cell recovery from proteasome inhibition independent of proteotoxic stress. Dual inhibition of the proteasome and autophagosome may therefore help overcome PI resistance, which remains an unmet need in MM. Figure 1 Figure 1. Disclosures Auner: Takeda, Karyopharm: Other: Advisory role; Amgen: Research Funding; Janssen: Speakers Bureau. Khwaja: Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astellas: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Yong: Sanofi: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Takeda: Honoraria; GSK: Honoraria; Amgen: Honoraria; BMS: Research Funding; Autolus: Research Funding.

Background: Upfront ASCT for NDTE MM continues to be challenged as standard of care due to high MRD neg rates following novel induction and consolidation (cons) strategies. The Cardamon study reported that KCd consolidation did not meet the statistical boundary for non-inferiority to ASCT following KCd induction, however the margin was small, with no benefit for MRD negative pts. For this analysis we focussed on the outcomes according to cytogenetic risk. Methods: NDTE pts received 4 x KCd induction (K 20/56 mg/m 2 biweekly, C 500 mg D 1,8,15, d 40 mg weekly) before 1:1 randomisation to ASCT or 4 x KCd cons. All received 18 months K maintenance (56mg/m 2 D1,8,15). High risk (HR) was defined as any one of the HR cytogenetic abnormalities (CA) del(17p) (≥50%), t(4;14), t(14;16), t(14;20), ultraHR (uHR) as ≥2 of the HR CA, 1p- or 1q+, and standard risk (SR) as neither HR nor uHR. CA were identified by FISH on CD138 enriched cells. Subgroup analyses evaluated the impact of each single CA, including t(11;14). Flow cytometric MRD (10 -5) was assessed post induction, pre-maintenance and after 6 months maintenance, on ITT basis. The primary objective of this analysis was outcomes according to cytogenetic risk, including the impact of treatment arm. Results: Of 281 pts registered, 259 were included with complete FISH data, 52 (20%) had HR CA, and 41 (16%) were uHR. Post induction, ≥VGPR rate was 60% in HR pts, 56% in uHR pts, and 59% in SR pts. MRD neg rates were 23%, 27% and 23% and increased to 53%, 56% and 45% with ASCT and 27%, 27% and 32% with Cons, for HR, uHR and SR respectively. With a median follow-up of 2.8 years, the observed 2-year PFS from randomisation for ASCT was 76.6% vs 68.8% for cons (HR: 0.77 (70% CI 0.61, 0.97), p=0.2); calculated difference in 2-year PFS rate (cons vs ASCT) was -6.2% (70% CI -10.7%, -0.1%, not non-inferior). HR and uHR pts had inferior outcomes to SR overall, with 2-year PFS rates of 49%, 50% and 76% respectively (HR vs SR: HR=2.58, p Analysis by single CA was limited by the small pt numbers in each group, however pts with t(4;14) had worse PFS (HR: 2.62, p While numbers are small and the interaction does not meet significance (p=0.16), pts with t(11;14) tended to demonstrate a benefit for ASCT over cons (2-year PFS 89% vs 67%). Conclusions: HR or uHR pts receiving KCd induction, followed by ASCT or KCd cons, had a significantly shorter PFS compared to SR pts. Consolidation with KCd did not meet the boundary for non-inferiority to ASCT, though the margin is small and none of the HR, uHR and SR cytogenetic risk groups had a statistically significant PFS benefit with ASCT. Disclosures Yong: GSK: Honoraria; Takeda: Honoraria; Janssen: Honoraria, Research Funding; BMS: Research Funding; Amgen: Honoraria; Sanofi: Honoraria, Research Funding; Autolus: Research Funding. Ramasamy: Karyopharm: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer oncology: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene (BMS): Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Conference registration, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Conference registration, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Conference registration, Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Conference registration, Research Funding; Adaptive biotech: Honoraria, Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Honoraria, Membership on an entity's Board of Directors or advisory committees; GSK: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees. Streetly: BMS-Celgene: Consultancy; Sanofi: Consultancy; EUSA Pharma: Consultancy. Clifton-Hadley: Bristol-Myers Squibb Pharmaceuticals Ltd..: Other: The haematology team at the CTC has received funding (which in part pays staff salary) to Sponsor and coordinate clinical trials.; Amgen: Other: The haematology team at the CTC has received funding (which in part pays staff salary) to Sponsor and coordinate clinical trials.; Celgene: Other: The haematology team at the CTC has received funding (which in part pays staff salary) to Sponsor and coordinate clinical trials.; Merck Sharp and Dohme: Other: The haematology team at the CTC has received funding (which in part pays staff salary) to Sponsor and coordinate clinical trials.; Janssen-Cilag: Other: The haematology team at the CTC has received funding (which in part pays staff salary) to Sponsor and coordinate clinical trials.; Pfizer: Other: The haematology team at the CTC has received funding (which in part pays staff salary) to Sponsor and coordinate clinical trials.; Millennium pharmaceutics inc.: Other: The haematology team at the CTC has received funding (which in part pays staff salary) to Sponsor and coordinate clinical trials.. Popat: GlaxoSmithKline: Consultancy, Honoraria, Research Funding; AbbVie, BMS, Janssen, Oncopeptides, and Amgen: Honoraria; Abbvie, Takeda, Janssen, and Celgene: Consultancy; Takeda: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; Janssen and BMS: Other: travel expenses.

Background: FDG PET-CT can assess bone, bone marrow and extramedullary disease (EMD) in multiple myeloma (MM), can identify disease missed through patchy marrow infiltration and complement established markers of adverse prognosis. The evolving definition of 'PET-CT high-risk disease' includes the presence of EMD and paramedullary involvement which are associated with inferior outcome. Other potential factors include SUV max >4.2 at baseline, < complete metabolic response (CMR) after autograft and >3 FDG avid focal lesions (FL). Methods: In the CARDAMON study, newly diagnosed MM patients eligible for ASCT received KCd (Carfilzomib, cyclophosphamide and dexamethasone) induction and either KCd consolidation or ASCT, then K maintenance for 18 cycles. In a consenting subgroup of patients, FDG PET-CT was performed at baseline, 14-28 days after completing consolidation or 100 days post-ASCT, and after 6 months maintenance. PET-CT scans were independently reviewed by 2 readers with PET positive lesions defined as uptake within focal lesions (FL) and/or diffuse marrow uptake > liver. A CMR required a Deauville score (DS) of 1-3 in FL and bone marrow. Results: Of 31 patients registered to the sub-study, 28 had available PET data and are included in this analysis, 61% male, median age 60 years (range 36-69). 14 patients had standard risk disease, 10 had isolated 1p-/1q+ and 4 had genetically HR disease (t(4;14), t(14;16), t(14;20) or del17p > 50% cells). Revised International Staging System (R-ISS) was I in 5/28, R-ISS II or III in 20/28 (unknown in 3/28). Baseline PET was positive (PP) in 21/28 patients (77.8%), negative (NP) in 6/28 (22.2%) and 1 patient had a baseline scan that was not evaluable. Of the PP group, 3 had diffuse disease only, 13 had focal disease only and 5 had both focal and diffuse disease. The focal and diffuse pattern was most frequently seen in PP patients with genetic HR disease. Median SUV max of FL in PP patients was 5.78 (range 2.19-12.93). 9/21 PP patients had >3 FL with uptake > liver at baseline and 19/21 had bone marrow DS >3. Patients with >3 FL had significantly worse PFS than those with ≤3 (HR = 5.41 (95% CI 1.05-27.9), p=0.04). There was a trend for higher presenting bone marrow trephine plasma cell involvement in PP patients at baseline (median PP 50% [range 15-85]), median NP 20% [range 1-70]) (p=0.07). PET-CT was positive at baseline in 4/5 R-ISS I patients and 15/21 R-ISS II/III. Three out of 4 patients with HR disease and evaluable scans had positive baseline PET-CTs; 1 with focal disease only and 2 with focal and diffuse disease. Of 16 patients who underwent 2 nd PET, 12 showed CMR and 1 partial metabolic response (PMR). Four patients withdrew before assessment, 3 for progressive disease and 1 death, and 3 patients had no FDG avid lesions at baseline and post-induction. Further analysis of patients with CMR showed 1 CR and minimal residual disease negative, (MRD-ve), 7 VGPR (4 MRD+ve, 3 MRD-ve) and 4 PR (2 MRD+ve, 2 MRD-ve). The 1 patient with PMR had a VGPR (MRD-ve). A further 11 patients underwent PET 6 months post maintenance of whom 5 remained in CMR and 5 were PET negative at baseline and response. Serological responses in the patients in CMR were 1 sCR (MRD-ve), 1 CR (MRD-ve) and 3 VGPR (1 MRD+ve, 2 MRD-ve). With a median follow-up of 2.3 years, median progression free survival (PFS) for patients in the sub-study has not yet been reached, compared to a median PFS for the whole cohort of 3.3 years (95% CI 2.8-N/A). Median overall survival (OS) is awaited, for both groups. In the PP group, 2-year PFS was 65.6% (95% CI 41.0-82.0) vs 100% (95% CI N/A) for NP group, however due to small numbers and limited follow-up this difference was not significant (p=0.2). Conclusions: In the CARDAMON PET sub-study over 75% of patients had a positive baseline PET. This group had heavier marrow burden, with predominant focal disease. Patients with focal disease and >3 FL with uptake >liver had a significantly worse PFS. Follow-up PET scans for those available for response assessment showed high rates of CMR (12/13, 92%) with variable depth of serological response and MRD. Overall, K maintenance sustained PET negativity at 6 months in 10/11 patients who underwent a 3rd scan. PET is a valuable addition to disease response measures; further work will clarify the role of increased monitoring and therapeutic adaptation in PET defined high-risk groups. Disclosures Popat: GlaxoSmithKline: Consultancy, Honoraria, Research Funding; Takeda: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES; AbbVie, BMS, Janssen, Oncopeptides, and Amgen: Honoraria; Abbvie, Takeda, Janssen, and Celgene: Consultancy; Janssen and BMS: Other: travel expenses. Ramasamy: Karyopharm: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive biotech: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Conference registration, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Conference registration, Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Conference registration, Research Funding; Oncopeptides: Honoraria, Membership on an entity's Board of Directors or advisory committees; GSK: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene (BMS): Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Conference registration, Research Funding; Pfizer oncology: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees. Streetly: BMS-Celgene: Consultancy; Sanofi: Consultancy; EUSA Pharma: Consultancy. Eccersley: Wolters-Kluwer: Honoraria. Clifton-Hadley: Amgen: Other: The haematology team at the CTC has received funding (which in part pays staff salary) to Sponsor and coordinate clinical trials.; Pfizer: Other: The haematology team at the CTC has received funding (which in part pays staff salary) to Sponsor and coordinate clinical trials.; Janssen-Cilag: Other: The haematology team at the CTC has received funding (which in part pays staff salary) to Sponsor and coordinate clinical trials.; Merck Sharp and Dohme: Other: The haematology team at the CTC has received funding (which in part pays staff salary) to Sponsor and coordinate clinical trials.; Celgene: Other: The haematology team at the CTC has received funding (which in part pays staff salary) to Sponsor and coordinate clinical trials.; Millennium pharmaceutics inc.: Other: The haematology team at the CTC has received funding (which in part pays staff salary) to Sponsor and coordinate clinical trials.; Bristol-Myers Squibb Pharmaceuticals Ltd..: Other: The haematology team at the CTC has received funding (which in part pays staff salary) to Sponsor and coordinate clinical trials.. Barrington: Bristol Myers Squibb international corporation: Research Funding; Pfizer Inc: Research Funding; Amgen Ltd: Research Funding; Takeda Speakers Bureau: Honoraria. Yong: Janssen: Honoraria, Research Funding; Sanofi: Honoraria, Research Funding; Autolus: Research Funding; Takeda: Honoraria; GSK: Honoraria; Amgen: Honoraria; BMS: Research Funding.

Introduction: Expression and function of BCL-2 family proteins in multiple myeloma (MM) is important for tumour cell survival and drug resistance, and may partly mediate the protective effect of bone marrow (BM) stroma. Proteasome inhibitors (PIs) are a major class of anti-myeloma drugs, however some patients are resistant and almost all eventually relapse. Carfilzomib is a second generation, irreversible proteasome inhibitor, which is effective in both newly diagnosed and relapsed/refractory disease, but drug resistance and relapse occur. Aim: We aimed to study the role of BCL-2 family proteins in Carfilzomib (CFZ) mediated cytotoxicity in the presence of stroma, focusing on priming of the pro-apoptotic protein, BIM. Methods: A panel of Human Myeloma Cell Lines (HMCL) and primary MM cells were exposed to Carfilzomib, and cell death assessed using Annexin V/PI staining and flow cytometry. Co-cultures employing the HS5 stromal cell line were used to model the interaction with stroma. MM cells were exposed to CFZ in a 1hr pulse, to recapitulate the pharmacokinetics of drug exposure in patients. The expression of BCL-2 family proteins was assessed by flow cytometry and Western Blot (WB). The compounds S63845, ABT-199 (Venetoclax) and A-1331852 were used to inhibit MCL-1, BCL-2 and BCL-X L pro-survival proteins respectively. Changes in BIM binding partners were examined by immunoprecipitation and WB. Results: CFZ induced dose and time-dependent cell death of HMCL and primary MM cells. This was primarily mediated by apoptosis as shown by AnV/PI staining (eg. MM1.s at 25nM CFZ: 34±6% apoptosis at 24h, 47±9% at 48h, p=0.016; 50nM CFZ: 60 ±3.8% at 24h vs 79±6% at 48h, p=0.004, mean ±SEM, n=3), and by reduced cytotoxicity in MM1.s BAX/BAK KO cells (100nM CFZ: 10±1% cell death vs 42±5% in WT at 6h, 33±14% vs 99±0.5% at 24h; p=0.0005, n=3). CFZ cytotoxicity was significantly reduced when MM1.s cells were co-cultured with HS-5 (50nM CFZ: 53±4% apoptosis vs 79±4% in suspension, at 48h, p=0.02, n=3) confirming the protective effect of stromal cells. Similar results were seen with H929, KMS27 and KMS12BM HMCL (Figure 1). Co-culture of MM1.s with HS-5 cells induced upregulation of MCL-1 and BCL-X L and downregulation of BCL-2. Combined inhibition of BCL-X L and MCL-1 at concentrations where single agents had minimal effect, resulted in a marked increase in apoptosis on stroma (Ctrl: 9±1%, S63845 100nM:12±1.4%, A-1331852 1nM: 17±3%, S63845+A-1331852: 60±9%; 48h, p=0.0001, n=3) (Figure 3). BIM immunoprecipitation showed that in the presence of the MCL-1 inhibitor, S63845, there was increased BCL-X L binding to BIM; conversely when BCL-X L was inhibited by A-1331852, an increase in MCL-1/BIM complexes was seen. Exposure of MM cells to CFZ in stromal co-cultures led to a further increase in the expression of BCL-X L and MCL-1. Because BCL-X L and MCL-1 were upregulated both by stromal interaction and by CFZ (Figure 2), we tested the cooperativity of these anti-apoptotic proteins on resistance to CFZ. CFZ-induced cytotoxicity was significantly enhanced by the addition of single BH3 mimetics in the presence of HS-5: cell death 48h, BCL-X L A-133182 5nM: 40±12%, CFZ 25nM: 57±10%, CFZ+A-1331852: 94±2%, p=0.0065, n=3. Cell death with MCL-1 inhibitor S63845 200nM: 12±3%, CFZ 25nM:40±13%, S63845+CFZ: 54±18%, p=0.02, n=3). However, combined BCL-X L and MCL-1 inhibition, using lower concentrations of BH3 mimetics, potently sensitized MM cells to CFZ-mediated cytotoxicity in the presence of stroma (% killing at CFZ 25nM + A-1331852 1nM: 48±8%; CFZ+S63845 100nM: 38±5%; CFZ+A-1331852+S63845: 92±2%, p Conclusion: BCL-X L and MCL-1 are upregulated in MM cells by stromal interaction, and also in response to CFZ. The upregulation of pro-survival proteins by stroma may mediate MM cell resistance to PIs, and blockade of both BCL-X L and MCL-1 is required in order to abrogate the protective effect of stroma and restore sensitivity to CFZ. Combination of BH-3 mimetic drugs at subtherapeutic doses with proteasome inhibitors may be a potential therapeutic strategy. Figure 1 Figure 1. Disclosures Huang: The Walter and Eliza Hall Institute of Medical Research: Patents & Royalties: Employee of the Walter and Eliza Hall Institute and eligilble for payments in relation to venetoclax. Khwaja: Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astellas: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Yong: Janssen: Honoraria, Research Funding; Sanofi: Honoraria, Research Funding; Takeda: Honoraria; GSK: Honoraria; Amgen: Honoraria; BMS: Research Funding; Autolus: Research Funding.

Background Concerns have been raised about the ability of patients with plasma cell disorders (PCD) to mount adequate immune responses to vaccination, particularly considering the initial extension to vaccination intervals in the United Kingdom to up to 12 weeks in December 2020, the start of the vaccination roll-out. Protecting this vulnerable patient group with anti-SARS-CoV-2 vaccination is critical. Methods We measured the humoral responses in PCD patients after the first dose of the BNT162b2 and ChAdOx-1 nCOV-19 vaccines. Antibody levels were measured using Elecsys Anti-SARS-CoV-2S assay for quantitative detection of IgG Abs, specific for the SARS-CoV-2 spike-protein receptor binding domain. Positive cut-off of ≥0.80 U/mL defined serologic response. Testing was performed at (or closest to) 4 and 8 weeks post-dose. Baseline nucleocapsid Ab results were available from previous screening in a subset of patients. Clinical information was retrieved from medical records. Results 198 PCD patients (178 multiple myeloma, 15 amyloid, 3 SMM/MGUS, other 2 PCD), median age 63 (range 35-84), had serologic assessment after one vaccine dose against SARS-CoV-2. 69% (138) were on chemo-immunotherapy treatment (CIT) within 4 weeks of first dose. Previous COVID-19 infection and exposure was defined as a positive COVID-19 PCR swab or positive N-antibody at baseline and were excluded from analysis. Patients were tested at median 42 days (range 11-90) after their first dose. After one dose, 68% (135/198) were seropositive, with median Ab titres 21 U/mL (IQR 3.92-133.5). In those with negative baseline Ab test, seroconversion to one dose was 67% (64/96). Forty-one patients were tested more than once after one dose, at median 33 days (12-62) and again at 67 days (38-91). 22 were seronegative at first testing, of these, 6 seroconverted on second testing, prior to second dose. Age ≥70, light chain (LC) disease, disease status less than VGPR, CIT within 4 weeks, low IgM and ASCT more than 12m were statistically significant seronegative predictors on univariate analyses. LC disease, less than VGPR and IgM less than 0.4g/L, retained statistical significance on multivariate analyses. On linear regression analysis in seropositive patients, more lines of treatment and CIT within 4 weeks were significantly associated with lower antibody titres. Conclusion Serologic response to SARS-CoV-2 vaccination is lower in PCD patients than reported healthy controls at 68% after one dose. Further work in PCD is needed to understand how Ab levels correlate to neutralisation capability, cellular responses, protection from infection and how long seroconversion lasts to better define correlates of protection. Nearly a third do not respond to a single vaccine dose causing concerns that PCD patients are left vulnerable with a delayed vaccination strategy and should be prioritised to receiving the second dose at the recommended manufacturers time scale of 3 or 4 weeks.

Background: Multiple Myeloma (MM) is an incurable plasma cell malignancy with significant genomic heterogeneity. It is usually preceded by the asymptomatic stage known as smoldering multiple myeloma (SMM). SMM patients have a 10% annual risk of progression to MM. Genomic alterations that are observed in SMM patients include chromosomal gains and losses, translocations, and point mutations. However, current SMM risk models rely solely on clinical markers that do not accurately capture the progression risk. While incorporating some genomic biomarkers improves prediction, using all MM genomic features to comprehensively stratify patients may increase the precision of risk models. Methods: We obtained a total of 214 patients' samples at SMM diagnosis in the US and Europe. We performed whole exome sequencing on 166 tumors; of these, RNA sequencing was performed on 100. Targeted capture with a MM gene panel was done on an additional 48 tumors. We identified subgroups using binarized DNA features and performing consensus binary non-negative matrix factorization. Results: We identified six clusters (C1-C6) with the following features: four with a hyperdiploidy (HD) (>48 chromosomes) and two with IgH translocations. These subgroups have unique transcriptomic profiles overlapping with known MM signatures and biological pathways. One of the clusters harboring translocation (11;14), which we call C4-CCND1, was enriched with the previously defined CD-2 MM signature that uniquely expresses B cell markers CD20 and CD79A; shows upregulation of CCND1 and E2F7; and is enriched with pathways like DNA replication, heme metabolism, and NFkB signaling. The C3-MS_MF cluster with the IgH translocations (4;14) and (14;16) shows downregulation of ribosomal genes, TRAF2, and DUSP2. The MYC oncogene was highly expressed in the four HD clusters: C1-HD_NRAS, C2-HD_MAFB, C5-HD_KRAS, and C6-HD_1q (BH-P = 0.037). The clusters also showed different outcomes in terms of time to progression (TTP) to active MM (P = 0.005). Median TTP for patients in C2-HD_MAFB, C3-MS_MF, and C5-HD_KRAS was 3.7, 2.6, and 2.2 years, respectively; TTP for C1-HD_NRAS, C4-CCND1, and C6-HD_1q was 4.3, 11, and not reached, respectively. In multivariate analysis, C2-HD_MAFB, C3-MS_MF, and C5-HD_KRAS were independent predictors of progression after accounting for the clinical risk stage. Moreover, the odds of having evolving hemoglobin and monoclonal protein levels in these three clusters were 3.5 and 12.3 times higher than the other clusters, respectively (P = 0.01 and 0.002). Conclusion: We identified six distinct SMM molecular groups with corresponding transcription profiles and dysregulated pathways. These groups have different progression risks to active MM, with three groups being independent predictors of progression. Our results underscore the importance of molecular classification in MM to better understand and target various tumor vulnerabilities. Citation Format: Shankara Anand, Mark Bustoros, François Aguet, Romanos Sklavenitis-Pistofidis, Robert Redd, Benny Zhitomirsky, Andrew J. Dunford, Yu-Tzu Tai, Selina J. Chavda, Cody Boehner, Carl J. Neuse, Tineke Casneuf, Lorenzo Trippa, Chip Stewart, Kwee Yong, Irene Ghobrial, Gad Getz. Genomic profiling of smoldering multiple myeloma classifies distinct molecular groups [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2240.

Immune dysregulation is described in multiple myeloma. While preclinical models suggest a role for altered T-cell immunity in disease progression, the contribution of immune dysfunction to clinical outcomes remains unclear. We aimed to characterize marrow-infiltrating T cells in newly diagnosed patients and explore associations with outcomes of first-line therapy.We undertook detailed characterization of T cells from bone marrow (BM) samples, focusing on immune checkpoints and features of immune dysfunction, correlating with clinical features and progression-free survival.We found that patients with multiple myeloma had greater abundance of BM regulatory T cells (Tregs) which, in turn, expressed higher levels of the activation marker CD25 compared with healthy donors. Patients with higher frequencies of Tregs had shorter PFS and a distinct Treg immune checkpoint profile (increased PD-1, LAG-3) compared with patients with lower frequencies of Tregs. Analysis of CD4 and CD8 effectors revealed that low CD4effector (CD4BM-infiltrating T-cell subsets, specifically Tregs and PD-1-expressing CD4 effectors, negatively influence clinical outcomes in newly diagnosed patients. Pending confirmation in larger cohorts and further mechanistic work, these immune parameters may inform new risk models, and present potential targets for immunotherapeutic strategies.

8000 Background: Upfront ASCT for NDTE MM remains under evaluation with high MRD rates following novel induction and consolidation (cons) strategies. Current phase 3 trials support ASCT, however these employ lenalidomide maintenance which predominantly benefits standard risk (SR) patients (pts). The CARDAMON trial investigated the role of ASCT using K based induction and maintenance. Methods: NDTE pts received 4 x KCd induction (K 20/56 mg/m2 biweekly, C 500 mg D 1,8,15, d 40mg weekly) before 1:1 randomisation to ASCT or 4 x KCd cons. All received 18 months K maintenance (56mg/m2 D1,8,15). Flow cytometric MRD (10-5) was assessed post induction, pre-maintenance and at 6 months maintenance. Primary endpoints were ≥VGPR post induction and 2-year PFS from randomisation. 210 randomised pts were needed to exclude a 10% non-inferiority margin with 15% 1-sided alpha, 80% power. Results: 281 pts were registered, median age 59y (33–74), 24% high risk [t(4;14), t(14;16), t(14;20) or del(17p)]. Post induction, ≥VGPR rate was 58.5%, ORR was 87% with similar responses for high risk vs SR. 52 pts did not proceed to PBSCH (6 MR, 16 PD, 19 toxicity, 4 deaths: 3 infection, 1 cardiac event, 7 other). 109 were randomised to ASCT, 109 to KCd cons. ≥VGPR rate was 78.5% after cons and 80.0% after ASCT (p = 0.8). Median KCd cons dose was 55.5 mg/m2, 99 (90.8%) pts completed 4 cycles, 104 (95.4%) pts received ASCT. After 2.6 years follow-up, median PFS was not reached for ASCT vs 3.8 years for cons (HR: 0.82 (70% CI 0.65, 1.05, p = 0.4). Observed 2-year PFS for ASCT was 75.5% vs 70.7% for cons; calculated difference in 2-year PFS rate (cons vs ASCT) was -4.5% (70% CI -9.2%, +1.1%, non-inferior). High risk pts had inferior outcomes to SR overall regardless of randomisation (2-year PFS ASCT: 52% vs 82% (HR 4.09); cons 48% vs 77% (HR 2.83)). 2 year PFS did not differ according to randomisation: SR 82% (ASCT) vs 77% (cons) HR: 1.29 (0.71-2.35); high risk: 52% (ASCT) vs 48% (cons) HR: 1.06 (0.50-2.23). MRD negativity post induction was 24.3% and similar by genetic risk. MRD negative rates were higher post ASCT (53.1%) than cons (35.8%) (p = 0.02) independent of genetics: SR 49% (ASCT) vs 36% (cons); high risk: 57% (ASCT) vs 32% (cons). G3+ adverse events to induction were infections (18.7%), hypertension (11.2%), anaemia (10.4%), cardiac disorders (3.6%), vomiting (2.2%), fatigue (2.2%), diarrhoea (1.8%). Conclusions: In NDMM receiving KCd induction and K maintenance, KCd cons was non-inferior to ASCT. High risk pts had inferior outcomes, that were not influenced by ASCT or cons randomisation. Clinical trial information: NCT02315716. [Table: see text]

A 22 year old woman was admitted to hospital with confusion, pyrexia, and two episodes of loss of consciousness while at work that day. She described having felt tired in the preceding week. She had no medical history of note and did not smoke or drink alcohol. She did not take any regular medications and did not use recreational drugs. The patient was born in the UK. Her parents were from Nigeria. She had no recent foreign travel or contact with anyone who was unwell. Her heart rate was 115 beats/min, blood pressure 100/80 mm Hg, temperature 38.5°C, respiratory rate 20 breaths/min, and oxygen saturations 100% on room air. Blood results are shown in table 1 and blood film in fig 1. View this table: Table 1 Blood test results Fig. 1 Blood film ×40 magnification 1. What is the most likely diagnosis? 2. What other initial tests are important? 3. How is this condition treated? ### 1. What is the most likely diagnosis? The following factors make thrombotic thrombocytopenic purpura (TTP) the most likely diagnosis: Fig. 2 Blood film ×40 magnification showing schistocytes and thrombocytopenia TTP requires immediate haematologist assessment. TTP is a thrombotic microangiopathy. Haemolytic uraemic syndrome, another thrombotic microangiopathy, is a differential. Thrombotic microangiopathy (TMA) is indicated by thrombocytopenia in the full blood count and microangiopathic haemolytic anaemia on the blood film.1 ADAMTS13 enzyme activity …

A 20 year old man was referred to the emergency department by his general practitioner with a one week history of easy bruising, gum bleeding, and lethargy. He had no medical history and took no regular medications. He did not smoke or drink alcohol and had no travel history. On examination, he appeared unwell and had widespread petechiae with evidence of gum bleeding. The rest of the clinical examination, including funduscopy, was normal. His observations were: heart rate 110 beats per minute, blood pressure 100/80 mm Hg, temperature 38.5°C, respiratory rate 20 breaths/minute, and oxygen saturations 100% on room air. Blood results showed: haemoglobin 77 g/L (133-167 g/L), white blood cell count 6×109 cells/L (3.5-11×109 cells/L), neutrophils 1.1×109 cells/L (2.0-7.0×109 cells/L), platelets 45×109/L (150-410×109/L), and C reactive protein level 160 nmol/L (0.76 −28.5 nmol/L). A coagulation screen showed INR 1.9 (0.8-1.1), APTT ratio 1.07 (0.85-1.15), fibrinogen 0.8 g/L (2-4 g/L), and D-dimer 3334 ng/ml (

Introduction: Carfilzomib (20/36mg/m2) triplets with Lenalidomide-Dexamethasone (KRd), or Cyclophosphamide-Dexamethasone (KCd) are safe and effective in patients with newly diagnosed multiple myeloma(NDMM). The higher dose of 56mg/m2 is effective as a doublet with Dexamethasone in the relapsed setting, but there is limited data on this dose in triplet combinations in the frontline setting. Aim: The CARDAMON study evaluated KCd with bi-weekly carfilzomib (56mg/m2) as induction in NDMM patients, and the benefit of ASCT versus K56Cd consolidation followed by carfilzomib maintenance. Co-primary endpoints were major response (≥VGPR rate) to 4 induction cycles of K56Cd, and 2-year PFS for ASCT versus K56Cd consolidation. Here we report interim analysis of the first primary endpoint of ≥VGPR rate to K56Cd induction. Methods: Transplant eligible ND patients received 4 x 28d cycles of K56Cd (carfilzomib:20/56mg/m2, IV d1, 2, 8, 9, 15, 16, cyclophosphamide 500mg orally d1, 8, 15 and dexamethasone 20mg d1, 2, 8, 9, 15, 16). Responding patients with a successful stem cell harvest (PBSCH) were randomised to autologous stem cell transplant (ASCT) or 4 more cycles of K56Cd as consolidation, followed by 18 months carfilzomib maintenance (K56 days 1, 8, 15) for both arms. Trial recruitment completed in July 2019. Response was assessed by IMWG criteria; all patients had MRD testing by multi-parameter flow cytometry (10-5) after PBSCH. Adverse risk genetics was any one of t(4;14), t(14;16), t(14,20) or del(17p). Results: 281 pts were registered between 06/2015 and 07/2019; we report outcomes for 252 patients who either completed induction or came off study before end of induction. Median age was 58yrs(33-74), 91% ECOG 0-1, 45.2% ISS I, 24.7% adverse risk (48.5% when including 1p/1q+). Best response at end of induction or after PBSCH (n=250) was: ≥VGPR 59.2%, ORR 87.6%. ≥VGPR rate in adverse risk patients was 53.4% vs 61.9% in standard risk(SR), (p=0.25), ORR was similar: adverse risk, 87.9% vs standard risk, 88.1%. Post-PBSCH, 24.1% of patients were MRD-negative (patients who were withdrawn due to insufficient induction response or toxicity and those with an inconclusive result were grouped with the MRD-positive). Of 19 patients in sCR/CR, 9 were MRD-negative(47.4%) while 40/110 (36.4%) of VGPR patients were MRD-negative. MRD-negative rates in adverse and standard risk patients were 22.8% and 24.7% respectively. 10 patients progressed during or at end of induction, and 12 were withdrawn for toxicity. There were 4 deaths during induction, one from myocardial infarction, the other 3 from cardiac arrest, associated with bronchopneumonia and sepsis. During induction, 114 serious adverse events (SAEs) were reported in 72/252 patients, notable ones were thrombotic microangiopathy (2), grade 3 cardiac ischaemia (4), infection (16.3%, mainly lung), renal impairment (6), G3 hypertension (3), thromboembolism(2). Specific guidance for hypertension management was incorporated. 25% of patients are currently reported to have received a dose modification during induction. Full details of adverse events and dose intensity will be presented at the meeting. Conclusion: K56Cd is an effective induction regimen in NDMM patients, and has equivalent MRD negative rates in adverse and standard risk disease. The SAE profile is in keeping with published safety data with carfilzomib. Disclosures Yong: Sanofi: Speakers Bureau; Amgen: Research Funding, Speakers Bureau; Autolus: Consultancy; Janssen: Speakers Bureau; Takeda: Research Funding, Speakers Bureau. Popat:Celgene Corporation: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel, accommodations, expenses; Janssen: Honoraria, Other: travel support to meetings; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; GSK: Consultancy, Honoraria; Takeda: Honoraria, Other: travel, accommodations, expenses. Ramasamy:Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; NAPP Pharmaceuticals Ltd.: Research Funding; Janssen-Cilag Ltd.: Research Funding; Oncopeptides and Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees. Chapman:Takeda: Honoraria. Benjamin:Allogene: Research Funding; Gilead: Honoraria; Novartis: Honoraria; Pfizer: Research Funding; Amgen: Honoraria; Takeda: Honoraria; Servier: Research Funding; Eusapharm: Consultancy. Owen:Celgene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Other: Travel/ meeting support. OffLabel Disclosure: Carfilzomib is used with cyclophosphamide as 1st line treatment for myeloma

Introduction: High dose therapy and autologous stem cell transplant (ASCT) remain standard first line therapy for young fit patients with multiple myeloma (MM). Beyond cytoreduction, ASCT may also alter the bone marrow (BM) immune environment to augment anti-tumour immune responses. A more precise understanding of the immune microenvironment post ASCT and its relationship with clinical outcomes may identify biomarkers to refine prognostication and provide opportunity for therapeutic intervention. Aim: We aimed to define T cell subsets and expression of co-activating and co-inhibitory proteins in the BM early post ASCT, and explore associations with clinical outcomes. Methods: BM samples were obtained at 100 days (D100) post ASCT from 61 MM patients, and 15 healthy donors (HD). BM mononuclear cells (MNCs) were stained for surface (CD3, CD4, CD8, PD-1, LAG-3, and ICOS) and intracellular markers (GzmB, Ki-67, CTLA-4, and FoxP3). Data were acquired on a BD LSR Fortessa and analysed using FlowJo. Progression free survival (PFS) was defined from ASCT as per IMWG criteria, and patient groups were compared using Mann-Whitney U test. Adverse risk genetics was defined as t(4;14), t(14;16) or del(17p). Results: Median age of patients at ASCT was 58yrs (36-71), 70.5% were male. Median follow up was 17 months (3-54). At diagnosis, 36.1% were ISS stage I, 8.2% had extramedullary disease, and 14.7% had adverse risk genetics. As induction therapy, 96.7% received a proteasome inhibitor, 45.9% an immunomodulatory drug, 54.1% both, and 21.3% received post ASCT maintenance/consolidation. Median PFS was 24 months. At D100, 24.6% had achieved CR, 47.5% VGPR, 21.3% PR, 4.9% SD and none had PD. Improved PFS was found in patients with deeper response (CR/VGPR vs. rest, p=0.003), and with ISS stage I vs II/III (p=0.013). There was a trend for improved PFS with standard risk genetics (p=0.088 cf high risk). MM BM contained lower frequencies of CD3 and CD4 T cells compared to HD (CD3, 28% of live MNCs, vs 41.2%, p=0.012; CD4, 4.1% vs 14.0%, p Immune checkpoint proteins were highly expressed on BM T cell subsets in post ASCT compared to HD. CD4eff in MM patients expressed higher frequency of PD-1, LAG-3, ICOS, CTLA-4, GzmB, and Ki-67 (p Clinical outcomes were not influenced by T cell subsets (CD3, CD4eff, CD8, and Treg) but there was an inverse association with co-inhibitory receptor expression. High frequency (>median) of LAG-3 on CD4eff and CD8, and Tregs was associated with shorter PFS (median 18mo vs 53, p=0.0028; 20mo vs 53, p=0.0057; 20mo vs 53, p=0.046 respectively). Further, patients with high frequency of PD-1 on CD4eff and Ki-67 on CD8 T cells had shorter PFS (median 18mo vs 36, p=0.042 and 18mo vs unreached, p=0.019 respectively). A multivariate Cox regression model was built to include ISS stage, depth of response at D100, and the immune phenotypes identified to correlate with PFS. In this model, high frequency of PD-1 on CD4eff retained independent prognostic value, along with ISS stage and CD8 Ki67+ T cells. Conclusion: We present data indicating that high frequency of PD-1+ CD4eff and Ki67+ CD8 T cells post ASCT associate with shorter PFS in MM patients. Pending confirmation in larger cohorts, these data reveal potential immune biomarkers for poor outcomes, and prompt deeper phenotypic analysis and mechanistic studies to uncover the immune drivers of sustained remissions post ASCT. Disclosures Lee: Autolus Therapeutics: Equity Ownership, Research Funding. Yong:Takeda: Research Funding, Speakers Bureau; Autolus: Consultancy; Amgen: Research Funding, Speakers Bureau; Janssen: Speakers Bureau; Sanofi: Speakers Bureau.

An 81 year old woman was referred to haematology with a six month history of fever, 7 kg weight loss, night sweats, and abdominal distension. She was otherwise fit and well; she had no travel history of note and did not smoke or drink alcohol. On examination, she had massive splenomegaly palpable to the level of the umbilicus. The examination was otherwise normal and she had no palpable lymphadenopathy in the cervical, axillary, or inguinal regions. Blood results showed haemoglobin 119 g/L (reference range 123-167), white blood cell count 68.0×109/L (3.5-11), lymphocytes 53.0×109/L (1.0-3.0), neutrophils 4.1×109/L (2.0-7.0), monocytes 6.8×109/L (0.2-1.0), and platelets 134×109/L (150-410). Urea, creatinine, and liver function tests were normal. A peripheral blood smear was performed (fig 1). Flow cytometry showed that 60% of total peripheral blood leucocytes were CD19, CD20, CD22, CD79b, CD25, CD11c, and CD103 positive surface immunoglobulin …

Background: Carfilzomib (CFZ) is a potent, irreversible proteasome inhibitor (PI) licenced in patients with multiple myeloma (MM) demonstrating improved progression free and overall survival (OS) to standard of care therapies. However, CFZ is also associated with hypertension (HTN) and rarely cardiac toxicity. The exact mechanism is unclear but may be due to a disturbance of endothelial nitric oxide synthase and nitric oxide. Incidence of HTN in a pooled analysis of CFZ trials (Chari et al, Blood 2018, n=2044) showed all grade (G): 18.5%, ≥G3 5.9%. There is less data in the real world setting. Methods: This was a single centre retrospective analysis of all patients treated with CFZ between 2015-2018. BP was recorded in routine nursing records prior to each CFZ infusion in triplicate at each visit 10 minutes apart and the median recorded. HTN was graded by CTCAE criteria V4 (note: G1=pre-HTN (120-139/ 80-89)) and pulmonary hypertension as mean pulmonary arterial pressure (mPAsp) >25mmHg (American College of Cardiology criteria). Baseline demographics were obtained from medical records. OS was estimated using Kaplan Meier Curves and correlative analysis by Cox regression models. Results: 86 patients and 1976 consecutive BP recordings were evaluated with a mean of 23 BP assessments per patient (1-74). Demographics are shown in Table 1. 32 patients (37.2%) had prior history of HTN and 14 (16.3%) had prior cardiac co-morbidity (ischaemic heart disease, dysrhythmias and cardiac amyloidosis). Initial dosing of CFZ was 20mg/m2, increasing to 27mg/m2 (n=30 (34.9%)), 36mg/m2 (n=18 (20.9%)), 45mg/m2 (n=2 (2.3%)), 56mg/m2 (n=35 (40.7%)), 70mg/m2 weekly (n=1(1.2%)). Median time on therapy was 5.3 months (0-26) with a median of 6 (1-27) cycles. The overall incidence of all grade HTN was 60 (69.8%), predominantly G1-2 and was similar in those with and without pre-existing HTN (Chi squared test p=0.4) (Table 2). 11(13%) required intervention with anti-HTN medications for ≥G2 HTN which then returned the BP to baseline. Those treated at ≥45mg/m2 of CFZ had more episodes of HTN compared to those treated at 27-36mg/m2 (OR 3.65, 95% CI: 1.39-9.21, p65 years was not associated with increased risk of HTN (OR 1.32, 95% CI 0.45-3.73, p=0.63) nor was ethnicity (Chi squared test p=0.1). 25 patients required treatment interruption for any cause, of which 12 were due to HTN (median 7 days (1-23)).13 patients required dose reduction for any cause, and 9(10%) required reductions due to HTN, mainly at 56mg/m2 (27 n=1(1.2%), 36 n=2(2.3%), 56 n=7(8.1%)). The planned median cumulative dose for the number of cycles received was 1264mg/m2 overall (36-5772) however, the actual median cumulative dose delivered was 784 mg/m2 (36-3248). The difference was the greatest with higher carfilzomib doses (≥56mg/m2 vs 27-45mg/m2 (Chi squared test, p 15(17%) patients developed cardiac complications including pulmonary HTN n=10(12%) and cardiac failure n=8(9%). Unlike HTN, cardiac complications were not associated with CFZ dose ( OS was unaffected by HTN, cardiac toxicity, pulmonary HTN or HTN related treatment delays (median OS not reached regardless of developing cardiovascular adverse events, HR 1.45 95% CI 0.39-5.37, p=0.57; median follow up 17 vs 31 months respectively). Conclusions: This real world data demonstrated a higher incidence of HTN compared to clinical trials, however most were low grade toxicities. This may be partly due to under-reporting of G1 events which may not be clinically significant. Dose reductions were more frequent at CFZ doses ≥45, leading to a reduction in total cumulative dose received. Close monitoring and early intervention for HTN is therefore required to prevent further complications and to maintain cumulative dosing. In this dataset, cardiac complications did not appear to be related to HTN. Disclosures Cheesman: Celltrion: Other: Speaker Fee; Roche: Other: Advisory board. Wechalekar:Janssen: Honoraria. Rabin:Janssen: Consultancy, Other: Travel support, Speakers Bureau; Takeda: Consultancy, Other: Travel support , Speakers Bureau; Celgene: Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau. Yong:Janssen: Honoraria, Speakers Bureau; Celgene: Honoraria; Takeda: Speakers Bureau; Amgen: Honoraria, Research Funding, Speakers Bureau. Popat:Amgen: Honoraria.

Background. Chemotherapy followed by ASCT is standard of care in fit transplant-eligible newly diagnosed patients with Multiple Myeloma (MM). Most patients, however, will relapse and require further treatment. With increasing choice of therapies at relapse, we need to understand the determinants of treatment outcomes for these patients, to aid management decisions and patient counselling. Methods. This was a retrospective analysis of sequential patients who relapsed from upfront ASCT carried out between 2000-2014. PFS1 was defined as time from ASCT to 1st progression or death; PFS2, time from ASCT to 2nd progression or death and 2nd PFS, time from start of salvage regimen to 2nd progression or death. Post relapse survival (PRS) was measured from progression date and overall survival (OS) from ASCT date. Disease response, and adverse FISH were assigned according to IMWG. Survival was estimated using Kaplan- Meier curves and correlative analysis by Cox regression models. Results. Of 474 patients undergoing ASCT (2000-2014), 277 relapsed with a median age of 58 years (range 29-70).The M:F ratio was 1.85:1. Isotypes identified were: IgG 57.0%, IgA 22.7%, light chain 15.9%. Median PFS1 from ASCT was 20 months (0.47-128.3). ORR pre-ASCT was 91.3% (sCR/CR 4.4%, VGPR 25.4%) and post ASCT was 95.3% (sCR/CR 14.5%, VGPR 52.2%). At relapse, median age was 60 years (30-73) and 36.5% of patients had ISS stage2-3 disease. For the 277 patients who relapsed, median OS from ASCT was 67 months (CI 57-73) and median PRS was 40 months (35-44). PFS1 had a strong influence on OS, HR 0.97 (95%CI: 0.96-0.97, p Patients relapsing before 2008 (prior to bortezomib funding) had shorter OS compared to those relapsing thereafter: median 61 vs 69 months, HR 1.38 (1.01-1.87, p=0.04). Depth of response (CR/VGPR) pre and post-ASCT were associated with longer PFS1- HR 0.70 (0.54-0.92, p=0.01), and HR 0.68(0.51-0.89, p=0.005) respectively, but not OS or PRS. 248 patients (89.5%) received systemic salvage therapy at relapse;106 patients (38.3%) experienced biochemical IMWG progression rather than clinical relapse, with median time to treatment of 5 months (2-64). Salvage regimens included: proteasome inhibitors(PIs) (64.5%), immunomodulatory agents (IMiDs, 29.8%, thalidomide-63.5%, lenalidomide-36.5%) and chemotherapy 5.2%; 26.6% of patients entered clinical trials and 13.7% underwent salvage ASCT. ORR was 70.4% (sCR/CR 10.9%, VGPR 31.6%). Median 2nd PFS was 17 months (16-20) and median PFS2 overall was 39 months (35-41). Achieving a deeper response to salvage treatment (CR/VGPR) was associated with a longer 2nd PFS (21 vs 17 months for PR, HR 0.65, 0.46-0.91, p=0.01), with a trend for PRS, HR 0.89(0.59-1.34, p=0.58) and OS, HR 0.77(0.51-1.17, p=0.22). Novel agents induced deeper responses, CR/VGPR with PI regimens 51.3%, with IMiDs 30%, and with chemotherapy 8%. Patients treated with PIs compared to all other systemic treatment regimens had a significantly longer OS of 80 vs 48 months, HR 0.60(0.43-0.85, p= 0.004). Patients entered into clinical trials (66) had deeper responses, ≥VGPR 61% compared to 31% in non-trial patients, and longer PRS, 64 vs 35 months, HR 0.54 (0.36-0.81, p= 0.003) and OS 90 vs 57 months, HR 0.50 (0.33-0.76, p=0.001). Risk factors at relapse influenced outcomes. Higher ISS was associated with shorter PRS, ISS 2/3 27 vs 50 months for ISS1, HR 2.52(1.74-3.66, p Conclusions. This real-world series shows that timing of relapse, period of relapse (pre-2008), ISS Stage, adverse FISH, and response to salvage regimen influence survival after relapse from frontline ASCT. Use of novel regimens, particularly PIs as salvage therapy post ASCT is associated with longer OS. Our data confirm the importance of entering patients into clinical trials. Multivariable linear regression analyses will be presented. Lastly, the inferior outcomes for patients with high-risk features highlights the need to develop different treatment strategies in this patient subgroup. Disclosures Maciocia: Autolus: Equity Ownership, Patents & Royalties: TRBC1 and 2 Targeting for the Diagnosis and Treatment of T-cell Malignancies. Yong:Janssen: Research Funding; Autolus Ltd: Equity Ownership, Patents & Royalties: APRIL based chimeric antigen receptor.

Background.The overall improvement in treatment outcomes and survival of multiple myeloma (MM) patients has highlighted the persistently poor outlook for patients with del(17p). Around a third of MM patients with del(17p) are also reported to have a TP53 mutation, while this mutation is rare in the absence of del(17p). The prognostic impact of TP53 mutations in the context of del(17p) is unresolved. We investigated the presence of TP53 mutations in a cohort of del(17p) patients to correlate mutation status with clinical outcome. We assessed the types of TP53 mutations, and the timing of mutations in relation to the acquisition of del(17p). Methods. CD138+ plasma cells were obtained from bone marrow of patients at diagnosis and prior to starting each new line of therapy, subjected to FISH analysis using standard probes, and surplus tumour cells banked. Between 2004-2015, we identified 52 patients who had at least one FISH result confirming del(17p) in ≥10% CD138+ cells, of whom 16 patients (30.8%) had del(17p) at diagnosis. In 22 patients, samples were available at more than one time point (2-4) for analysis. Clinical details, including treatment and disease response (2014 IMWG criteria) were collated. Adverse risk FISH was defined as t(4;14), t(14;16) and 1q+. Genomic DNA was extracted from CD138+ plasma cells using DNeasyBlood & Tissue Kit (Qiagen). 87 gDNAsamples were amplified by PCR and screened for TP53 mutations in exons 4-11 using DHPLC. TP53 mutations were verified by Sanger sequencing. Survival was estimated using Kaplan-Meier methods, and differences were assessed by log-rank test with p-values Results. TP53 mutations were identified in 19 (36.5%) patients, and there was no significant difference in median age at diagnosis between patients with or without mutations (61.3 vs 57.3 years, p=0.07). Of the 16 patients with del(17p) at diagnosis, 5 (31.3%) had a TP53 mutation in the diagnostic sample, while 14 (38.8%) of the 36 patients in the relapse subgroup had a mutation (p=0.8). Of the 18 TP53 variants identified, 17 were single nucleotide variants (SNV), of which 14 (82.4%) were missense mutations, 2 were nonsense mutations and 1 altered a splice site; all were documented on the IARC TP53 database. One patient had a novel in-frame indel. The majority of mutations occurred in exons 5, 6 and 8, which forms an integral part of the p53 DNA binding domain. Most mutations identified were predicted to produce a non-functional protein with less than 20% transcriptional activity, as specified by the IARC database. Eleven (57.9%) of the TP53 mutated patients also had at least one high risk genetic feature compared to 16 (48.5%) of the non-TP53 mutated patients (p=0.6). For relapse patients, median time from diagnosis to acquisition of del(17p) was 34.5 months (range 1-178), and median time from acquisition of del(17p) to TP53 mutation was 4 months ( In 3 patients with TP53 mutations detected at relapse, a preceding sample confirmed to harbour del(17p) was non-mutated, and occurrence of the mutation occurred at 24, 37 and 39 months after del(17p) was first detected. A further 2 patients had a sample preceding del(17p) acquisition, in which there was no TP53 mutation. For the remainder of patients, del(17p) and TP53 mutation were picked up simultaneously. Median overall survival (OS) from diagnosis was significantly shorter for TP53 mutated patients (23 vs 74 months, p=0.03). Median OS from time of del(17p) acquisition was also significantly shorter for TP53 mutated patients (14 vs 29 months, p=0.01), although PFS from next line of therapy was similar (7 vs 12 months, p=0.70). The median survival of TP53 mutated patients from first detection of mutant TP53 was 7 months. Summary. TP53 mutations are common in del(17p) MM with a broad range of variants, the majority of which are likely to produce non-functional variant proteins. The acquisition of TP53 mutations seems to occur after allelic loss of 17p, and to confer even worse clinical outcomes. In the era of genomic medicine, there is a case for routinely screening for TP53 mutations in these patients, to aid in management decisions and patient counselling. An urgent need exists to develop therapies to counteract the loss of this tumour suppressor pathway. Disclosures Yong: Autolus Ltd: Equity Ownership, Patents & Royalties: APRIL based chimeric antigen receptor; Janssen: Research Funding.