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Multiple myeloma (MM) is a highly refractory hematologic cancer. Targeted immunotherapy has shown promise in MM but remains hindered by the challenge of identifying specific yet broadly representative tumor markers. We analyzed 53 bone marrow (BM) aspirates from 41 MM patients using an unbiased, high-throughput pipeline for therapeutic target discovery via single-cell transcriptomic profiling, yielding 38 MM marker genes encoding cell-surface proteins and 15 encoding intracellular proteins. Of these, 20 candidate genes were highlighted that are not yet under clinical study, 11 of which were previously uncharacterized as therapeutic targets. The findings were cross-validated using bulk RNA sequencing, flow cytometry, and proteomic mass spectrometry of MM cell lines and patient BM, demonstrating high overall concordance across data types. Independent discovery using bulk RNA sequencing reiterated top candidates, further affirming the ability of single-cell transcriptomics to accurately capture marker expression despite limitations in sample size or sequencing depth. Target dynamics and heterogeneity were further examined using both transcriptomic and immuno-imaging methods. In summary, this study presents a robust and broadly applicable strategy for identifying tumor markers to better inform the development of targeted cancer therapy. Significance: Single-cell transcriptomic profiling and multiomic cross-validation to uncover therapeutic targets identifies 38 myeloma marker genes, including 11 transcribing surface proteins with previously uncharacterized potential for targeted antitumor therapy.

Cellular therapy modalities, including autologous (auto-) hematopoietic cell transplantation (HCT), allogeneic (allo-) HCT, and now chimeric antigen receptor (CAR) T cell therapy, have demonstrated long-term remission in advanced hematologic malignancies. Auto-HCT and allo-HCT, through hematopoietic rescue, have permitted the use of higher doses of chemotherapy. Allo-HCT also introduced a nonspecific immune-mediated targeting of malignancy resulting in protection from relapse, although at the expense of similar targeting of normal host cells. In contrast, CAR T therapy, through genetically engineered immunotherapeutic precision, allows for redirection of autologous immune effector cells against malignancy in an antigen-specific and MHC-independent fashion, with demonstrated efficacy in patients who are refractory to cytotoxic chemotherapy. It too has unique toxicities and challenges, however. Non-Hodgkin lymphoma (including large B cell lymphoma, mantle cell lymphoma, and follicular lymphoma), B cell acute lymphoblastic leukemia, and multiple myeloma are the 3 main diseases associated with the use of fully developed CAR T products with widespread deployment. Recent and ongoing clinical trials have been examining the interface among the 3 cellular therapy modalities (auto-HCT, allo-HCT, and CAR T) to determine whether they should be "complementary" or "competitive" therapies. In this review, we examine the current state of this interface with respect to the most recent data and delve into the controversies and conclusions that may inform clinical decision making.

Advances in multiple myeloma therapies have greatly improved outcomes for patients living with the disease, although to date there is yet to be a cure. Cellular and immunotherapies, approved or in development, offer the promise of significantly advancing toward that possibility. The aim of this review is to provide a synopsis and commentary on the current and future states of bispecific agents aimed at harnessing the antineoplastic potential of T-cells in treating and eradicating myeloma.Numerous bispecific agents are in clinical development with some on the precipice of regulatory approval. While BCMA remains the principal target, some agents are directed at novel targets such as GPRC5D and FcRH5. The constructs vary in design and pharmacokinetics which has dosing and administration implications. The toxicity profiles of these agents generally reflect that of other immune therapies, including cytokine release syndrome and rarely neurotoxicity, although immunosuppression has also led to elevated infection risks. However, the toxicities are generally manageable and offset by unprecedented efficacy seen in such heavily pretreated cohorts. Bispecific agents are poised to significantly alter the treatment paradigms for myeloma. They provide a convenient "off-the-shelf" platform with often deep and durable responses. Toxicities are often limited in duration and severity. In the early-phase trials, many patients have been able to remain on treatment for extended periods, even among those with high-risk features. Upcoming trials are likely to explore earlier implementation of these agents in order to offer this therapeutic opportunity to broader cohorts.

Multiple myeloma (MM) is a highly refractory hematologic cancer. Targeted immunotherapy has shown promise in MM but remains hindered by the challenge of identifying specific yet broadly representative tumor markers. We analyzed 53 bone marrow (BM) aspirates from 41 MM patients using an unbiased, high-throughput pipeline for therapeutic target discovery via single-cell transcriptomic profiling, yielding 38 MM marker genes encoding cell-surface proteins and 15 encoding intracellular proteins. Of these, 20 candidate genes were highlighted that are not yet under clinical study, 11 of which were previously uncharacterized as therapeutic targets. The findings were cross-validated using bulk RNA sequencing, flow cytometry, and proteomic mass spectrometry of MM cell lines and patient BM, demonstrating high overall concordance across data types. Independent discovery using bulk RNA sequencing reiterated top candidates, further affirming the ability of single-cell transcriptomics to accurately capture marker expression despite limitations in sample size or sequencing depth. Target dynamics and heterogeneity were further examined using both transcriptomic and immuno-imaging methods. In summary, this study presents a robust and broadly applicable strategy for identifying tumor markers to better inform the development of targeted cancer therapy.Significance:Single-cell transcriptomic profiling and multiomic cross-validation to uncover therapeutic targets identifies 38 myeloma marker genes, including 11 transcribing surface proteins with previously uncharacterized potential for targeted antitumor therapy.

Pearson R correlation values between bulk RNA expression and scRNA expression in PCs for target genes.

Multiple myeloma, light chain amyloidosis, and other plasma cell dyscrasias are characterized, in part, by abnormal production of paraproteins that are often responsible for the sequelae of those diseases. These paraproteins are whole or fragmented immunoglobulins produced by clonal antibody-secreting cells (usually plasma cells, but occasionally, B lymphocytes). Significant heterogeneity exists in the presentation of these diseases, ranging from incidental detection of a monoclonal protein in an asymptomatic patient, to life-threatening manifestations that require urgent diagnostic confirmation and intervention. Successful management of such scenarios requires a fundamental understanding of the laboratory assays at one's disposal, their role in the workup of paraproteinemias, and the interpretation thereof. This review broadly covers these assays and their roles in the diagnosis, prognosis, and management of these diseases.

To report the activity of venetoclax in patients with relapsed mantle cell lymphoma (MCL), we identified 81 patients treated with venetoclax monotherapy (n=50, 62%) or in combination with a BTK inhibitor (n=16, 20%), an anti-CD20 monoclonal antibody (n=11, 14%), or others at 12 US academic medical centers. Patients had high-risk disease features including Ki67 >30% (61%), blastoid/pleomorphic histology (29%), complex karyotype (34%), and TP53 alterations (49%), and received a median of 3 prior treatments including BTK inhibitors in 91%. Venetoclax alone or in combination resulted in an overall response rate (ORR) of 40% and median progression-free (PFS) and overall survival (OS) of 3.7 and 12.5 months, respectively. The receipt of ≤ 3 prior treatments was associated with higher odds of response to venetoclax in a univariable analysis. In a multivariable analysis, having a high-risk MIPI score prior to venetoclax and disease relapse or progression within 24 months of diagnosis were associated with inferior OS whereas the use of venetoclax in combination was associated with superior OS. Although most patients (61%) had low risk for tumor lysis syndrome (TLS), 12.3% of patients developed TLS despite the implementation of several mitigation strategies. In conclusion, venetoclax resulted in good ORR but short PFS in high-risk patients with MCL and may have a better role in earlier lines of treatment and/or in combination with other active agents. TLS remains an important risk in patients with MCL who initiate treatment with venetoclax.

Daratumumab, pomalidomide, and dexamethasone (DPd) is an FDA-approved 3rd or later line of therapy for myeloma. However, as there are limited published data on the efficacy of 2nd-line DPd, we conducted a retrospective analysis (n = 33). Herein, we report our center's data for 2nd-line DPd. Our patient population had a high amount of high risk cytogenetics (45.5%). The overall response rate (ORR) was 84.9% with a 1-year Progression Free Survival (PFS) of 37.7%. In standard risk myeloma (n = 18), the ORR was 88.9% and 1-year PFS was 61.1% (95% CI 42.3-88.3%). In high risk myeloma (45.5%, n = 15), the ORR was 80% with a 1-year PFS of 7.3% (95% CI 1.1-47.9%). This suggests that the efficacy of 2nd-line DPd in myeloma with high risk cytogenetics should be further investigated.

Community respiratory viral infections (CRVIs) are associated with pulmonary function impairment, alloimmune lung syndromes and inferior survival in human leucocyte antigen (HLA)-matched allogeneic haematopoietic stem cell transplant (HCT) recipients. Although the incidence of viral infections in HLA-haploidentical HCT recipients who receive post-transplant cyclophosphamide (PTCy)-based graft-versus-host disease (GVHD) prophylaxis is reportedly increased, there are insufficient data describing the incidence of CRVIs and the impact of donor source and PTCy on transplant outcomes. Analysing patients receiving their first HCT between 2012 and 2017 for acute myeloid leukaemia, acute lymphoblastic leukaemia and myelodysplastic syndromes, we describe comparative outcomes between matched sibling transplants receiving either calcineurin-based GVHD prophylaxis (SibCNI, N=1605) or PTCy (SibCy, N=403), and related haploidentical transplants receiving PTCy (HaploCy, N=757). The incidence of CRVIs was higher for patients receiving PTCy, regardless of donor type. Patients in the HaploCy cohort who developed a CRVI by day +180 had both a higher risk of treatment-related mortality [hazard ratio (HR) 2⋅14, 99% confidence interval (CI) 1⋅13-4⋅07; P=0⋅002] and inferior 2-year overall survival (HR 1⋅65, 99% CI 1⋅11-2⋅43; P=0⋅001) compared to SibCNI with no CRVI. This finding justifies further research into long-term antiviral immune recovery, as well as development of preventive and treatment strategies to improve long-term outcomes in such patients.

In this review we highlight the most recent studies furthering the clinical development of selinexor, a novel exportin-1 inhibitor, for the treatment of multiple myeloma and non-Hodgkin lymphomas.Three pivotal trials, the SADAL trial for diffuse large B-cell lymphoma, and the BOSTON and selinexor treatment of refractory myeloma trials for multiple myeloma, have recently led to the regulatory approval of selinexor monotherapy or combination regimens. They are complemented by several earlier phase clinical trials with iterative combinations, adding selinexor to novel therapies and cytotoxic chemotherapy regimens at various stages in the disease courses. In some, selinexor appears synergistic, occasionally overcoming treatment refractoriness, whereas in other situations appears additive. Consistent issues with tolerability are seen across trials, although consensus guidelines on their preemption and management have recently been adopted which may improve treatment success. While comparative data are lacking, the efficacy of selinexor-based regimens does not approach that of contemporaneous cellular and immunotherapies.Selinexor is a novel and potentially synergistic therapy for lymphoid malignancies, although requires refined supportive measures and strategies to improve its efficacy. Likely, for continued success, it will need to identify niches that complement recent advances, such as bridging to cellular therapies or maintenance thereafter.

Prior studies suggest increased cytomegalovirus (CMV) infection after haploidentical donor transplantation with posttransplant cyclophosphamide (HaploCy). The role of allograft source and posttransplant cyclophosphamide (PTCy) in CMV infection is unclear. We analyzed the effect of graft source and PTCy on incidence of CMV infection, and effects of serostatus and CMV infection on transplant outcomes. We examined patients reported to the Center for International Blood and Marrow Transplantation Research between 2012 and 2017 who had received HaploCy (n = 757), matched related (Sib) with PTCy (SibCy, n = 403), or Sib with calcineurin inhibitor-based prophylaxis (SibCNI, n = 1605). Cumulative incidences of CMV infection by day 180 were 42%, 37%, and 23%, respectively (P < .001). CMV disease was statistically comparable. CMV infection risk was highest for CMV-seropositive recipients (R+), but significantly higher in PTCy recipients regardless of donor (HaploCy [n = 545]: hazard ratio [HR], 50.3; SibCy [n = 279]: HR, 47.7; SibCNI [n = 1065]: HR, 24.4; P < .001). D+/R− patients also had increased risk for CMV infection. Among R+ or those developing CMV infection, HaploCy had worse overall survival and nonrelapse mortality. Relapse was unaffected by CMV infection or serostatus. PTCy was associated with lower chronic graft-versus-host disease (GVHD) overall, but CMV infection in PTCy recipients was associated with higher chronic GVHD (P = .006). PTCy, regardless of donor, is associated with higher incidence of CMV infection, augmenting the risk of seropositivity. Additionally, CMV infection may negate the chronic GVHD protection of PTCy. This study supports aggressive prevention strategies in all receiving PTCy.

Multiple myeloma (MM) almost invariably progresses through novel therapies. Patients with quad-refractory MM (refractory to bortezomib, carfilzomib, lenalidomide, and pomalidomide) and penta-refractory MM (additional refractoriness to daratumumab) have few treatment options. Two chemotherapy regimens, bendamustine/prednisone (BP) and dexamethasone, cyclophosphamide, etoposide, and cisplatin (DCEP), are often used in quad- and penta-refractory MM, but there are limited data on outcomes in this heavily pre-treated population. We conducted a single-center retrospective study to identify all patients who received DCEP and/or BP for quad- or penta-refractory MM. Disease response and refractoriness were defined by International Myeloma Working Group criteria. The primary endpoint was overall response rate (ORR). Secondary endpoints included overall survival (OS), progression-free survival (PFS), and duration of response (DOR). We identified 27 patients who received BP for quad- or penta-refractory MM. The median number of prior lines of therapy was 6. The ORR for BP was 26%. The median PFS for BP was 1.4 months (95% CI 1.1–1.6) and median OS was 8.7 months (95% CI 2.3–15.0). Patients treated with cyclophosphamide had less response to BP. Thirty-one patients received DCEP for quad-refractory or penta-refractory MM. The median number of prior treatment regimens was 8. The ORR to DCEP was 35%. The median PFS was 2.7 months (95% CI 1.5–3.8) and median OS was 6.2 months (95% CI 4.4–7.8). DCEP and BP retain efficacy in quad- and penta-refractory MM. Our analysis supports prospective study of these regimens, possibly in combination or in comparison with other agents in this area of unmet need.

Since its initial approval in 2015, daratumumab has had a tremendous impact on the treatment of multiple myeloma. It is a monoclonal antibody that targets CD38, an antigen with high surface expression on multiple myeloma cells. While it initially received approval as a monotherapy for multiply relapsed multiple myeloma, its favorable toxicity profile allowed for combinations with other novel myeloma therapies leading to numerous indications as a component of triplet and quadruplet regimens. These indications now span relapsed/refractory populations and both transplant-eligible and transplant-ineligible patients with newly diagnosed myeloma. Further investigations are underway to continue to expand the reach of daratumumab, including large phase III collaborative trials to assess the efficacy of daratumumab as part of post-transplant maintenance and its impact on smoldering myeloma. The recent introduction of a subcutaneous formulation of daratumumab with proven noninferiority will improve the convenience and accessibility of the drug. In this review, we examine the preclinical development of daratumumab, its pharmacology and clinical investigations that demonstrated its safety and efficacy. Furthermore, we discuss the outstanding questions related to daratumumab and ongoing clinical trials seeking to answer them.

The use of post-transplantation cyclophosphamide (PTCy) for graft-versus-host disease (GVHD) prophylaxis in recipients of haploidentical and fully matched transplantations is on the increase. Published studies have reported an increased incidence of cytomegalovirus (CMV) infection with the use of PTCy. Limited data exist on the incidence and outcomes of infection with non-CMV herpesviruses (NCHV) in this setting. The aim of this study was to evaluate the cumulative incidence of NCHV infections and the association of NCHV infections with transplantation-specific outcomes in recipients of haploidentical transplantation with PTCy (HaploCy), matched sibling donor transplantation with PTCy (SibCy), and matched sibling donor transplantation with calcineurin inhibitor-based prophylaxis (SibCNI). We hypothesized that, like CMV infection, HaploCy recipients of also will have a higher risk of NCHV infections. Using the Center for International Blood and Marrow Transplantation Research database, we analyzed 2765 patients (HaploCy, n=757; SibCNI, n=1605; SibCy, n=403) who had undergone their first hematopoietic stem cell transplantation (HCT) between 2012 and 2017 for acute myelogenous leukemia, acute lymphoblastic leukemia, or myelodysplastic syndrome. The cumulative incidence of NCHV at 6 months post-NCT was 13.9% (99% confidence interval], 10.8% to 17.3%) in the HaploCy group, 10.7% (99% CI, 7.1% to 15%) in the SibCy group, and 5.7% (99% CI, 4.3% to 7.3%) in the Sib CNI group (P < .001). This was due primarily to a higher frequency of human herpesvirus 6 viremia reported in patients receiving PTCy. The incidence of Epstein-Barr viremia was low in all groups, and no cases of post-transplantation lymphoproliferative disorder were seen in either PTCy group. The incidence of NCHV organ disease was low in all 3 cohorts. The development of NCHV infection was associated with increased treatment-related mortality, particularly in the HaploCy group. There was no association with the development of GVHD, relapse, or disease-free survival. Patients in PTCy cohorts who did not develop NCHV infection had lower rates of cGVHD. This study demonstrates that the use of PTCy is associated with an increased risk of NCHV infection. The development of NCHV infection was associated with increased nonrelapse mortality, especially in the HaploCy group. Prospective trials should consider viral surveillance strategies in conjunction with assessment of immune reconstitution for a better understanding of the clinical relevance of viral reactivation in different HCT settings.

Background Limited data are available on the clinical activity of venetoclax (ven) in mantle cell lymphoma (MCL). In 2 small retrospective studies of patients (pts) with MCL previously treated with BTK inhibitors (BTKi), ven resulted in overall response rates (ORRs) of 50-53% and median overall survival (OS) of 9-14 months (Eyre et al, Haematologica 2019; Zhao et al, Am J Hematol 2020). We sought to report the clinical activity of ven and identify factors associated with outcomes in a larger cohort of pts. Methods We included pts with relapsed MCL from 12 US medical centers treated with ven alone or in combination with an antiCD20 monoclonal antibody (mAb) or a BTKi. Response was determined by the local investigator. We defined OS as time from start of ven to death. Pts not experiencing an event were censored at their last known follow up. OS was determined using the Kaplan-Meier method, and univariable (UVA) and multivariable (MVA) models were developed to identify predictors of response and OS. Results Eighty-one pts were included. Pt characteristics (Table) at diagnosis (dx) were: median age 64 years (yrs) (range 38-87), male 79%, stage III/IV 95%, Ki67 >30% in 61% (available n=62), blastoid/pleomorphic histology 29% (available n=75) and ≥3 cytogenetic abnormalities 34% (available n=62). BCL2 expression was present in 93% (available n=40). Frontline treatment (tx) included intensive chemotherapy [defined as including high-dose cytarabine and/or autologous transplant (ASCT) in first remission] in 52% with ASCT in first remission in 32%. Median number of therapies prior to ven was 3 (range 1-8) including antiCD20 mAb 99%, alkylator 93%, BTKi 91%, anthracycline 58%, cytarabine 56%, and lenalidomide 37%. 55% were refractory (defined as stable (SD) or progressive disease (PD)) to last tx prior to ven. ORR to BTKi prior to ven (n=70) was 66% (complete response (CR) 20%) with median duration of tx of 6.4 months (range 0.5-69). BTKi was stopped due to PD 82% and toxicity 18%. Median time from dx to start of ven was 3.9 yrs (range 0.2-17.8). Ven was given as monotherapy in 62% (n=50) and in combination with BTKi 20% (n=16), antiCD20 mAb 14% (n=11), or other 5% (n=4). Ten pts treated with ven in combination with BTKi received prior tx with BTKi with ORR to BTKi of 40% (all PR). Ven highest dose received was 20-100 mg in 12% (n=9), 200 mg 11% (n=8), 400 mg 61% (n=46), and 800 mg 17% (n=13). Median duration of tx with ven was 2.8 months (range 0.1-30). The best response to ven was CR 18%, partial response (PR) 24%, SD 11%, and PD 47% with ORR of 42%; 19 pts (23%) did not have available data for response. ORR was not significantly different with ven monotherapy 36% (13/36) vs ven + antiCD20 mAb 56% (5/9) vs ven + BTKi 43% (6/14) (p=.559), or with ven monotherapy 36% vs combination therapy 50% (13/26) (p=.274). Ven was stopped due to PD 69%, toxicity 9%, allogeneic transplant 3% or other reasons 19%. Laboratory tumor lysis syndrome (TLS) occurred in 10 pts (12%) including 3 (3.7%) with clinical TLS. 38 pts received post-ven tx with median time from stopping ven to next tx of 0.24 months (range 0-2.2); for the 33 pts with available data, the best response to post-ven tx was CR 24%, PR 27%, SD 9% and PD 39% with ORR of 51%. For the 75 pts with available data, median OS was 12.5 months (95% CI 6-17) with 3-year OS of 13.1% (95% CI 1.4-38.0%) (Figure A). Median OS was numerically longer with ven combination (28.7 months, 95% CI 4-not reached) vs monotherapy (8.6 months, 95% CI 4.7-14.4), p=.0825 (Figure B). Median OS did not significantly differ based on response (CR/PR vs SD/PD) to prior tx with BTKi (14.4 vs 9.5 months, p=.53, Figure C) or last tx prior to ven (16.7 vs 12.4 months, p=.14, Figure D). In MVA for response, achieving CR/PR with BTKi prior to ven (vs SD/PD) was associated with response to ven (odds ratio 3.48, 95% CI 1.01-12.05, p=.049). In MVA for OS, ven combination vs monotherapy (HR 0.13, 95% CI 0.03-0.53; p=.006), longer time from dx to start of ven (>4 vs ≤4 yrs) (HR 0.08, 95% CI 0.02-0.36; p=.001), and higher dose of ven (≥400 mg vs 6 vs ≤6 months) (HR 3.47, 95% CI 1.10-10.99; p=.038) was associated with inferior OS. Conclusions In these high-risk and heavily pretreated pts with MCL, ven resulted in low response rate and poor OS. Ven may have a better role in MCL in earlier lines of therapy and when combined with other agents such as BTKi and/or antiCD20 mAbs. Disclosures Kamdar: Roche: Research Funding. Greenwell:Lymphoma Research Foundation: Research Funding; Acrotech Biopharma LLC, Kyowa Kirin: Consultancy. Hess:ADC Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; BMS, AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Portell:Acerta/AstraZeneca: Research Funding; Kite: Consultancy, Research Funding; Amgen: Consultancy; Janssen: Consultancy; Pharmacyclics: Consultancy; Bayer: Consultancy; BeiGene: Consultancy, Research Funding; AbbVie: Research Funding; TG Therapeutics: Research Funding; Infinity: Research Funding; Roche/Genentech: Consultancy, Research Funding; Xencor: Research Funding. Goldsmith:Wugen Inc.: Consultancy. Grover:Genentech: Research Funding; Tessa: Consultancy. Riedell:Morphosys: Research Funding; Celgene/Bristol-Myers Squibb Company: Honoraria, Research Funding; Verastem Oncology: Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Kite Pharmaceuticals/Gilead: Honoraria, Research Funding; Bayer: Honoraria; Karyopharm Therapeutics: Honoraria. Karmali:BeiGene: Speakers Bureau; AstraZeneca: Speakers Bureau; Karyopharm: Honoraria; Takeda: Research Funding; Gilead/Kite: Honoraria, Other, Research Funding, Speakers Bureau; BMS/Celgene/Juno: Honoraria, Other, Research Funding, Speakers Bureau. Kumar:AbbVie: Research Funding; Kite Pharmaceuticals: Honoraria, Other: Honoraria for Advisory Board; Astra Zeneca: Honoraria, Other: Honoraria for Advisory Board; Celgene: Honoraria, Other: Honoraria for Advisory Board; Seattle Genetics: Research Funding; Pharmacyclics: Research Funding; Celgene: Research Funding; Adaptive Biotechnologies,: Research Funding. Hill:Abbvie: Consultancy, Honoraria, Research Funding; Pharmacyclics: Consultancy, Honoraria, Research Funding; Beigene: Consultancy, Honoraria, Research Funding; AstraZenica: Consultancy, Honoraria, Research Funding; Kite, a Gilead Company: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria; BMS: Consultancy, Honoraria, Research Funding; Karyopharm: Consultancy, Honoraria, Research Funding; Takeda: Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Genentech: Consultancy, Honoraria, Research Funding. Kahl:AstraZeneca Pharmaceuticals LP: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Consultancy; AbbVie: Consultancy; Genentech: Consultancy; Pharmacyclics LLC: Consultancy; Roche Laboratories Inc: Consultancy; BeiGene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Acerta: Consultancy, Research Funding; ADC Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Cohen:Genentech, BMS, Novartis, LAM, BioInvent, LRF, ASH, Astra Zeneca, Seattle Genetics: Research Funding; Janssen, Adicet, Astra Zeneca, Genentech, Aptitude Health, Cellectar, Kite/Gilead, Loxo: Consultancy. OffLabel Disclosure: Venetoclax is not licensed for use in mantle cell lymphoma

Introduction The clinical application of the Revised International Staging System (R-ISS) for multiple myeloma may be limited by heterogeneity in clinical interphase fluorescent in situ hybridization (FISH) practices for detecting chromosomal abnormalities (CAs). Next generation sequencing (NGS)-based FISH (Seq-FISH) has demonstrated improved sensitivity and similar specificity relative to clinical FISH, and provides a standardized, single-pass method for identifying high-risk CAs. To date, calculating R-ISS stage using Seq-FISH (R-ISS-NGS) has not been validated. Patients and Methods We identified 672 patients with sufficient data to calculate R-ISS-NGS from the Multiple Myeloma Research Foundation (MMRF) CoMMpass Study. R-ISS-NGS was calculated from original ISS stage, lactate dehydrogenase, and CAs detected by Seq-FISH. Endpoints included overall survival and progression-free survival. We conducted multivariate analyses controlling for age and gender in order to compare outcomes across stages I to III of both the original ISS and R-ISS-NGS. Results The median follow-up was 24 months. The R-ISS-NGS resulted in significant redistribution of patients into stage II, relative to the original ISS. With respect to stage I, R-ISS-NGS stages II and III of were associated with worse progression-free survival or overall survival, more so than the staging schema of the ISS, thus validating the use of Seq-FISH in staging. Conclusion Using CAs detected by Seq-FISH and data from the CoMMpass study, we validated the R-ISS with a large, generalizable cohort. This study validates the substitution of Seq-FISH for clinical FISH, especially in large registry studies. Additionally, use of the validated R-ISS-NGS will strengthen outcomes research generated from the CoMMpass study.

Multiple myeloma (MM) is characterized by the uncontrolled proliferation of plasma cells. Despite recent treatment advances, it is still incurable as disease progression is not fully understood. To investigate MM and its immune environment, we apply single cell RNA and linked-read whole genome sequencing to profile 29 longitudinal samples at different disease stages from 14 patients. Here, we collect 17,267 plasma cells and 57,719 immune cells, discovering patient-specific plasma cell profiles and immune cell expression changes. Patients with the same genetic alterations tend to have both plasma cells and immune cells clustered together. By integrating bulk genomics and single cell mapping, we track plasma cell subpopulations across disease stages and find three patterns: stability (from precancer to diagnosis), and gain or loss (from diagnosis to relapse). In multiple patients, we detect “B cell-featured” plasma cell subpopulations that cluster closely with B cells, implicating their cell of origin. We validate AP-1 complex differential expression (JUN and FOS) in plasma cell subpopulations using CyTOF-based protein assays, and integrated analysis of single-cell RNA and CyTOF data reveals AP-1 downstream targets (IL6 and IL1B) potentially leading to inflammation regulation. Our work represents a longitudinal investigation for tumor and microenvironment during MM progression and paves the way for expanding treatment options., Clonal evolution in multiple myeloma (MM) needs to be understood in both the tumor and its microenvironment. Here the authors perform single-cell multi-omics profiling of samples from MM patients at different stages, finding transitions in the immune cell composition throughout progression.

Over the last few years, there has been great progress in the treatment of multiple myeloma (MM), with many new agents and combinations having been approved and being now routinely incorporated into treatment strategies for newly diagnosed patients. As a result, patients are experiencing benefits in terms of survival and better tolerance. However, the multitude of treatment options also presents a challenge to select the best options tailored to the specific patient situation. Frontline autologous stem cell transplantation (ASCT) is the standard of care for fit patients younger than age 71 who are newly diagnosed with MM, and triplet combinations are the backbone of induction therapy before ASCT. Post-transplant consolidation and prolonged lower-intensity maintenance are two strategies that have been used to deepen responses and delay progression. For older patients not eligible for ASCT, lenalidomide (len) is increasingly being used as part of frontline therapy, and current approaches are now targeting combinations of anti-CD38 antibodies. Strategies for selecting therapeutic regimens for older adults newly diagnosed with MM can be augmented with use of predictive tools to better capture physiologic age and estimate treatment tolerance. Here we review a decade of trials identifying clinical endpoints and toxicities relevant for the frontline treatment of younger patients and older adults.

Background:The rapid outbreak of coronavirus disease 2019 (COVID-19) led to delays of non-urgent or routine medical care. Regulatory waivers and policy changes from the Centers of Medicare and Medicaid Services (CMS) for the use of telehealth came as a solution to help fight the outbreak. The aim of this project was to survey the change in the frequency of use of telehealth services among multiple myeloma (MM) patients during the COVID-19 pandemic. Methods:We utilized HealthTree Cure Hub For Multiple Myeloma (healthree.org) and invited patients with active MM cancer or precursor conditions to participate in an online survey. We analyzed patient responses to doctor visits, the use of telehealth before and after the COVID-19 pandemic, and whether they had sufficient access to their doctor. Results:1,301 MM pts participated in the survey between April 15, 2020, and June 8, 2020. During the pandemic, 36% of patients indicated visiting with their physician less often than before, 2% visited more often, and 62% had no change in the frequency of their visits. The percent of patients responding “Sometimes” or “Yes” to the use of telehealth are reported here. Before the pandemic, 10% of patients used telehealth, while 62% of patients indicated using telehealth during the pandemic, a 523% increase. When asked if they had sufficient access to their MM healthcare provider 90% of patients indicated that they did, while 10% indicated they did not. Conclusions:There were significantly fewer in-person visits during the COVID-19 pandemic likely due to the CDC-recommended physical distancing practices. During this time, telehealth use among MM patients dramatically increased compared to telehealth use before the pandemic. It is reasonable to assume that patients indicated having sufficient access to their healthcare provider as a result of patients receiving care through telehealth visits. The authors encourage readers to think more broadly about the benefits of telehealth. Maintaining sufficient access to one healthcare provider addressed in this abstract is only a fraction of the benefits telehealth offers. MM is a rare cancer and as a result, some states have few if any specialists. Maintaining telehealth policy changes made during the pandemic would remove geographical barriers and open access to specialists across the country. Citation Format: Nathan W. Sweeney, Scott R. Goldsmith, Jennifer M. Ahlstrom. Telehealth use among multiple myeloma patients during the COVID-19 pandemic [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 716.

Multiple myeloma (MM) is a hematological cancer of the antibody-secreting plasma cells. Despite therapeutic advancements, MM remains incurable due to high incidence of drug-resistant relapse. In recent years, targeted immunotherapies, which take advantage of the immune system's cytotoxic defenses to specifically eliminate tumor cells expressing certain cell surface and intracellular proteins have shown promise in combating this and other B cell hematologic malignancies. A major limitation in the development of these therapies lies in the discovery of optimal candidate targets, which require both high expression in tumor cells as well as stringent tissue specificity. In an effort to identify potential myeloma-specific target antigens, we performed an unbiased search for genes with specific expression in plasma and/or B cells using single-cell RNA-sequencing (scRNAseq) of 53 bone marrow samples taken from 42 patients. By comparing >40K plasma cells to >97K immune cells across our cohort, we were able to identify a total of 181 plasma cell-associated genes, including 65 that encode cell-surface proteins and 116 encoding intracellular proteins. Of particular interest is that the plasma cells from each patient were shown to be transcriptionally distinct with unique sets of genes expressed defining each patient's malignant plasma cells. Using pathway enrichment analysis, we found significant overrepresentation of cellular processes related to B-Cell receptor (BCR) signaling, protein transport, and endoplasmic reticulum (ER) stress, involving genes such as DERL3, HERPUD1, PDIA4, PDIA6, RRBP1, SSR3, SSR4, TXNDC5, and UBE2J1. To note, our strategy successfully captured several of the most promising MM therapeutic targets currently under pre-clinical and clinical trials, including TNFRSF17(BCMA), SLAMF7, and SDC1 (CD138). Among these, TNFRSF17 showed very high plasma cell expression, with concomitant sharp exclusion of other immune cell types. To ascertain tissue specificity of candidate genes outside of the bone marrow, we analyzed gene and protein expression data from the Genotype-Tissue Expression (GTEx) portal and Human Protein Atlas (HPA). We found further support for several candidates (incl. TNFRSF17,SLAMF7, TNFRSF13B (TACI), and TNFRSF13C) as being both exclusively and highly expressed in lymphoid tissues. While several surface candidates were not found to be lymphocyte-restricted at the protein level, they remain relevant considerations as secondary targets for bi-specific immunotherapy approaches currently under development. To further investigate potential combinatorial targeting, we examine sample-level patterns of candidate co-expression and mutually-exclusive expression using correlation analysis. As the majority of our detected plasma cell-specific genes encode intracellular proteins, we investigated the potential utility of these epitopes as therapeutic targets via MHC presentation. Highly expressed candidates include MZB1, SEC11C, HLA-DOB, POU2AF1, and EAF2. We analyzed protein sequences using NetMHC and NETMHCII to predict high-affinity peptides for common class-I and class-II HLA alleles. To correlate MHC allelic preference with candidate expression in our cohort, we performed HLA-typing for 29 samples using Optitype. To support our scRNAseq-driven findings, we cross-referenced gene expression data with 907 bulk RNA-sequencing samples, including 15 from internal studies and 892 from the Multiple Myeloma Research Foundation (MMRF), as well as bulk global proteomics data from 4 MM cell lines (TIB.U266, RPMI8226, OPM2, MM1ST) and 4 patients. We see consistent trends across both cohorts, with high positive correlation (Pearson R ranging between 0.60 and 0.99) for a majority of genes when comparing scRNA and bulk RNA expression in the same samples. Our experimental design and analysis strategies enabled the efficient discovery of myeloma-associated therapeutic target candidates. In conclusion, this study identified a set of promising myeloma CAR-T targets, providing novel treatment options for myeloma patients. Disclosures Goldsmith: Wugen Inc.: Consultancy. DiPersio:Magenta Therapeutics: Membership on an entity's Board of Directors or advisory committees.

Single-institution studies suggest increased incidence of CMV infection (DNAemia/organ disease) in recipients of haploidentical grafts with PTCy (HaploCy). It is unclear what factors confer the increased risk. Given increased use of PTCy in matched-sibling donor transplant (SibCy), we examined the impact of donor type and PTCy on transplant outcomes by donor(D)/recipient(R) CMV serostatus and reported CMV DNAemia by day 180. Patients reported to the CIBMTR with AML/ALL/MDS receiving HaploCy (n = 757), SibCy (n=403), or Sib with calcineurin inhibitor and methotrexate/mycophenolate mofetil (SibCNI, n=1605) between 2012 and 2017 were examined (Table 1). Too few MUD with PTCy were reported to include MUD cohorts. Cumulative incidences of CMV DNAemia by d180 were 42% (99% CI, 37-46), 37% (31 - 43), and 23% (20 - 26) for HaploCy, SibCy, and SibCNI respectively [p Our study shows that PTCy is associated with higher incidence of CMV infection among both Haplo and Sib transplants. Among seropositive and CMV-infected patients, HaploCy had worse OS and TRM, whereas differences between SibCy and SibCNI were not significant. Neither CMV infection nor serostatus affect relapse. This study supports use of more aggressive prevention strategies in patients receiving PTCy and at risk for CMV infection.

There are reports of high rates of viral infections after haploidentical transplant, particularly in the setting of PTCy (HaploCy) but detailed data on incidence are lacking. We describe here the comparative incidence of community respiratory virus (CRV) infections occurring by day 180 post-transplant by donor source and their impact on outcomes including survival, relapse, chronic GVHD, and transplant related mortality (TRM) using CIBMTR registry data. The analysis included 2765 patients, all > 2 years of age, who underwent first allogeneic HCT for AML, ALL or MDS from 100 centers between 2012 and 2017 receiving either HaploCy (n=757), Matched related donor (MRD) transplant with PTCy (SibCy n= 403), and MRD transplant with calcineurin inhibitor and either MTX or MMF (SibCNI n= 1605). The cumulative incidences of CRV in the HaploCy, SibCy and SibCNI were: 3% (99% CI, 1.6-4.8), 3% (1.3-5.5) and 2.4 %(1.5-3.5) respectively at day 30 (P =0.649, NS), but notably higher at 15.5% (12.3-19), 16.2% (11.7-21.2) and 9.4 %(7.6-11.4) at 6 months (P

Secondary hemophagocytic lymphohistiocytosis (HLH) is an acquired syndrome of immune dysregulation.1-3 Depending on the severity of manifestations, therapy ranges from observation alone to combinations of corticosteroids, etoposide, and/or cyclosporine, based on treatment data in familial HLH.4,5 Notably, there is a paucity of data on salvage therapies.6-8 Key inflammatory cytokines that propagate HLH bind to receptors that signal via the JAKs, which phosphorylate the STAT transcription factors.9,10 The JAK/STAT cascade promotes expression of genes that further expand the hyperinflammatory state. Das et al11 developed a murine model of secondary HLH in which repeated cytosine guanine dinucleotide DNA injection into wild-type B6 mice triggered the innate immune response via Toll-like receptor 9. Subsequent inhibition of JAK1/2 via ruxolitinib led to resolution of splenomegaly and cytopenias, reduction of inflammatory cytokines, and attenuation of pathologic T-cell expansion. Maschalidi et al12 observed such findings in perforin knockout mice. Using these same models, Albeituni et al13 showed the superiority of ruxolitinib over interferon-γ inhibition (the target of emapalumab-lzsg), providing broader immune normalization and improving symptoms and survival. Here we describe 2 consecutive cases in which ruxolitinib was used as salvage therapy for refractory secondary HLH. Ruxolitinib resulted in rapid and complete resolution of clinical manifestations, obviating the need for further intensive chemotherapy or allogeneic stem cell transplantation.

Multiple myeloma (MM) almost invariably progresses through novel therapies. Patients with quad-refractory MM (refractory to bortezomib, carfilzomib, lenalidomide, and pomalidomide) and penta-refractory MM (additional refractoriness to daratumumab) have few treatment options. Two chemotherapy regimens, bendamustine/prednisone (BP) and dexamethasone, cyclophosphamide, etoposide, and cisplatin (DCEP), are often used in quad- and penta-refractory MM, but there are limited data on outcomes in this heavily pre-treated population. We conducted a single-center retrospective study to identify all patients who received DCEP and/or BP for quad- or penta-refractory MM. Disease response and refractoriness were defined by International Myeloma Working Group criteria. The primary endpoint was overall response rate (ORR). Secondary endpoints included overall survival (OS), progression-free survival (PFS), and duration of response (DOR). We identified 27 patients who received BP for quad- or penta-refractory MM. The median number of prior lines of therapy was 6. The ORR for BP was 26%. The median PFS for BP was 1.4 months (95% CI 1.1-1.6) and median OS was 8.7 months (95% CI 2.3-15.0). Patients treated with cyclophosphamide had less response to BP. Thirty-one patients received DCEP for quad-refractory or penta-refractory MM. The median number of prior treatment regimens was 8. The ORR to DCEP was 35%. The median PFS was 2.7 months (95% CI 1.5-3.8) and median OS was 6.2 months (95% CI 4.4-7.8). DCEP and BP retain efficacy in quad- and penta-refractory MM. Our analysis supports prospective study of these regimens, possibly in combination or in comparison with other agents in this area of unmet need.

EZH2 is a histone methyltransferase that suppresses genes involved in cell cycle control. Overexpression of EZH2 has been associated with a poor prognosis in various malignancies. Pawlyn et al recently reported poor outcomes in patients with multiple myeloma and overexpression of EZH2. In order to validate these findings, we analyzed EZH2 expression and outcomes among patients from the CoMMpass study.We extracted clinical, expression, and genomic data from Interim Analysis 13 of the MMRF CoMMpass study, which harbors data from over 1000 patients with multiple myeloma. Correlations were drawn between EZH2 expression and common genetic mutations. We analyzed the association of EZH2 overexpression with progression-free (PFS) and overall survival (OS).The estimated median PFS for patients with EZH2 overexpression was 20.2 months (95% confidence interval [CI], 16.3-25.5 months) compared with 37.2 months (95% CI, 31.5-40.7 months) for patients without (P .001). The estimated median OS for patients with EZH2 overexpression was 52.3 months (95% CI, 38.5 months to unable to quantitate), whereas the median OS had not been reached for those without (P .001). EZH2 overexpression was more common in those with 17p and 1q deletions, TP53 missense mutations, and certain KRAS mutations. Coinciding BRAF and EZH2 amplification occurred frequently.EZH2 overexpression is associated with worse outcomes among patients with multiple myeloma from the CoMMpass study. Its known association with p53 and other drivers of malignancy support further lab-based and clinical study in multiple myeloma.

e20024 Background: Chimeric antigen receptor (CAR) T-cell therapies are in clinical development for multiple myeloma (MM). Patient-reported outcomes (PRO) can provide valuable insights into how patients perceive the relative risks and benefits of these new therapies. This study aimed to evaluate CAR T-cell therapy in relapsed/refractory MM (RRMM) patients. Methods: We utilized HealthTree Cure Hub for Multiple Myeloma to analyze patient-reported data from 17 patients who participated in CAR T-cell clinical trials. In this study, we examined total prior lines of therapy, time to next treatment (TNT), overall survival (OS), patient-reported toxicity and severity, and patient-reported outcomes (myeloma reduction or no myeloma reduction). The Kaplan-Meier model was used to calculate overall survival. The severity of toxicity was assessed using a 1 to 10 scale (1 = minimal and 10 = severe). Results: Our analysis of the 17 patients found a median of 10 lines of therapy prior to CAR T-cell treatment. Ten patients had no new treatments to report at the time of this study, 5 patients reported new treatment with a median TNT of 15.9 months, and for 2 patients we did not have data. The median OS was 24 months (95% CI 21-30 months). The probability that a patient remained alive at 2 years was 0.48 (95% CI: 0.195, 1). Four of the 17 patients died with a median of 22.5 months post-CAR T-cell therapy. Two of these patients died without reporting a change in treatment. There was a total of 36 different side effects reported by patients as a result of the therapy. Table lists the side effects experienced by 2 or more patients and the corresponding average severity. Finally, 76% of patients treated with CAR T-cell therapy reported a reduction in their myeloma, four of these patients had m-protein levels reported and saw an average decrease of 93%. Of the remaining patients, three (18%) reported little to no reduction in their myeloma, and one patient (6%) did not know their response at the time of this analysis. Conclusions: Our investigation of patient-reported results suggests an emerging and viable immunotherapy treatment option for RRMM, with encouraging outcomes and manageable side effects. Future directions include analysis of genetics and treatment options post CAR T-cell therapy. These data highlight the expedited benefit of using PROs via an online platform, like HealthTree Cure Hub, to assess new therapeutics in the research community.[Table: see text]

e20022 Background: Patient-reported data play a critical role in assessing clinical benefit from therapeutic interventions and are increasingly used in clinical trials. Internet-based platforms such as HealthTree Cure Hub for Multiple Myeloma ( www.healthtree.org ) provide the opportunity to obtain such real-world patient-reported data, while also providing valuable insights into high-yield areas to focus on quality-improvement efforts. For example, proteasome inhibitor (PI)-based maintenance after autologous stem cell transplantation (ASCT) is a consensus recommendation in many practice guidelines for high-risk multiple myeloma (MM) yet real-world adherence to this practice remains uncertain (PMID 23541011, 30932732). Methods: We examined post-ASCT maintenance therapy in patients with high-risk MM, as defined per mSMART criteria, using patient-reported treatment data from the HealthTree Cure Hub for Multiple Myeloma database. Patients who received an ASCT prior to 2014 were excluded. Results: Our analysis identified 110 MM patients with high-risk MM. Of those, only 48 (44%) received PI-based maintenance therapy. Additionally, 60 (55%) received IMiD (immunomodulatory imide drug) maintenance, 1 (< 1%) received ‘other’, and 1 (< 1%) did not report maintenance therapy. Conclusions: The benefits of PI-based maintenance in MM are well established for high-risk MM. However, analysis of patient-reported data using an online patient portal, HealthTree Cure Hub for Multiple Myeloma, suggests a disparity between practice recommendations and real-world practice patterns. These findings, and others from online patient portals, can serve as a springboard in helping investigators to identify areas for quality-improvement initiatives.

Isatuximab is an IgG1 monoclonal antibody targeting CD38 that has received regulatory approval in combination regimens for patients with relapsed/refractory multiple myeloma. CD38 is an antigen with high surface expression on multiple myeloma cells. While daratumumab holds most of the market share for this drug class, isatuximab offers several unique aspects including a mechanism of action that may involve more direct myeloma-cell inhibition and killing and less reliance on cross-linking and immune effector cells, as well as subgroup data from pivotal trials showing notable efficacy in populations with renal impairment, high-risk cytogenetics and the elderly. While the administration of the drug remains intravenous, studies of fixed-volume infusion and rapid infusion may improve drug administration convenience. Ongoing studies are examining isatuximab in combination with other immune therapies and cellular therapies, conventional chemotherapy and across other disease entities.

There are multiple recent publications demonstrating an association between the development of post-transplant cytomegalovirus (CMV) infection and a reduced incidence of relapse in patients who receive allogeneic hematopoietic cell transplantation (allo-HCT).[1][1]–[3][2] This was demonstrated in

Donor-lymphocyte infusion (DLI) for relapse following haploidentical hematopoietic cell transplantation (haploHCT) with post-transplant cyclophosphamide (PTCy) has been described in recipients of bone marrow grafts, but not recipients of G-CSF mobilized peripheral blood (PB) grafts. We retrospectively identified patients who underwent DLI following PB-haploHCT with PTCy for relapse, or loss of chimerism (LOC). Twelve patients (57%) received DLI for hematologic relapse/persistent disease, seven (33%) for extramedullary relapse and two (10%) for LOC. Sixteen (76%) received chemotherapy prior to DLI, which did not correlate with response. The most common first dose was 1 × 106 CD3+ cells/kg. Two patients developed grade I aGvHD post DLI, one had grade II and two had grade III. One developed mild skin cGvHD 1361 days post DLI. Pre-DLI aGvHD predicted post-DLI aGvHD (P=0.025). Six patients achieved CR after DLI for overt relapse, one achieved full donor chimerism after LOC. Patients with LOC or EM relapse had superior relapse-free survival following DLI (P=0.029). DLI following PB-haploHCT with PTCy is a viable salvage therapy for overt relapse or LOC without a substantial increase in GvHD, and donor lymphocytes may be collected simultaneously with graft collection to facilitate availability in patients at high risk of relapse.

Historically, high-dose therapy in combination with autologous stem cell transplants (ASCT) for multiple myeloma (MM) was reserved for younger patients. In more recent years, the use of ASCT has expanded in the older population. However, there is still limited data on the utilization and efficacy of ASCT in older patients, particularly those over the age of 75. To further evaluate this issue, we retrospectively analyzed all patients with newly diagnosed MM between the ages of 75-78, the institutional cutoff for ASCT eligibility, that were referred to the stem cell transplant unit at our institution for consultation from the years 2012-2018. Baseline characteristics, anti-myeloma treatments, and patient outcomes were abstracted through chart review. Seventy-five patients were referred to our institution. 71% were male, 29% female. 39% patients were considered ineligible for ASCT by the consulting transplant physician. Most patients were considered transplant ineligible due to comorbidities or poor performance status. Of the 46 patients eligible for ASCT, 52% underwent the procedure during their first-line therapy. The majority of those patients received reduced intensity melphalan (140 mg/m2) while 2 patients received conventional dosing (200 mg/m2). The other 22 patients eligible for ASCT declined or elected to defer the procedure and to be treated with conventional therapy. The characteristics of these three groups were similar and are detailed in Table 1. After a median follow-up of 30 months, 25% of the patients had expired. Estimated median overall survival (OS) was 71.3 months (unable to quantitate 95% CI) for all patients. Compared to transplant eligible patients, regardless of transplant receipt, those who were transplant ineligible had a 186% increase risk for death (HR 2.86; 95% CI 1.12-7.35; p = 0.029). There was also a notable trend for longer OS in those who underwent ASCT compared to those who were eligible but declined the procedure, but it was not statistically significant (HR 0.36; 95% CI 0.10-1.28; p = 0.114). At a transplant center, two-thirds of patients referred for newly diagnosed MM between the ages 75-78 were considered eligible for ASCT and one-third underwent the procedure. Outcomes were better for patients eligible for ASCT, regardless of whether they underwent the procedure. There was also a trend for better OS in patients who underwent the procedure compared to those who declined. While small sample sizes and the retrospective nature of the study limit our ability to draw conclusions, it appears that ASCT has an OS benefit among patients age 75-78. Disclosures Fiala: Incyte: Research Funding. Stockerl-Goldstein:AbbVie: Equity Ownership; Abbott: Equity Ownership. Vij:Genentech: Honoraria; Janssen: Honoraria; Bristol-Myers Squibb: Honoraria, Research Funding; Sanofi: Honoraria; Karyopharm: Honoraria; Takeda: Honoraria, Research Funding; Celgene: Honoraria, Research Funding. Wildes:Janssen: Research Funding; Carevive: Consultancy.

Multiple myeloma (MM) is a disease defined by clonal proliferation of abnormal plasma cells from B-cells. Improved treatments for MM have led to improving overall lifespan, but still remains incurable due to acquired resistance to therapy and tumor heterogeneity. Single-cell RNA sequencing studies (scRNA-seq) of MM patients have highlighted the significant inter-individual heterogeneity and subclonal architecture of the malignant plasma cell populations, emphasizing the importance of developing personalized therapies specific to a patients molecular pathogenesis. In this study, we have integrated scRNA-seq with single-cell proteomics (sc-Prot) for 10 plasma cells and CD4+ T cells to validate and prioritize driver events in malignant cells and evaluate the tumor microenvironment. This effort will be expanded to another 10 cases to further integrate scRNA-seq, snATAC-seq, whole exome sequencing and bulk RNA-sequencing on a fraction of the cells isolated from bone marrow. The remaining cells will be sorted using FACS to select for specific malignant and immune cells including 40 plasma cells, 15 CD4+ T and 15 CD8+ T cells. These sorted cells will be profiled with a scProt technology (BASIL nanoPOTS) to illuminate their cell-to-cell heterogeneity. In our pilot study comparing bulk and single-cell proteomic data of a single patient's plasma cells (CD138+) for 400 representative proteins, while a majority of expression signatures are concurrent between the two methods, some signaling pathways including translation and apoptotic cleavage are discordant. Our findings stress the importance of interrogating subpopulations of immune and malignant cells at the single-cell level to further refine the transcriptomic and proteomic heterogeneity of MM in a cell type specific manner. With the aid of single-cell technology, we have assessed the heterogeneity of malignant and immune cell types to evaluate transcriptomic and proteomic changes contributing to altering the interplay between the immune environment and tumor cells. Disclosures Fiala: Incyte: Research Funding. Rettig:WashU: Patents & Royalties: Patent Application 16/401,950. O'Neal:Wugen: Patents & Royalties: Patent Pending; WashU: Patents & Royalties: Patent Pending. DiPersio:WUGEN: Equity Ownership, Patents & Royalties, Research Funding; Macrogenics: Research Funding, Speakers Bureau; Cellworks Group, Inc.: Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy; Magenta Therapeutics: Equity Ownership; RiverVest Venture Partners Arch Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees; NeoImmune Tech: Research Funding; Karyopharm Therapeutics: Consultancy; Incyte: Consultancy, Research Funding; Amphivena Therapeutics: Consultancy, Research Funding; Bioline Rx: Research Funding, Speakers Bureau. Vij:Bristol-Myers Squibb: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Genentech: Honoraria; Janssen: Honoraria; Karyopharm: Honoraria; Sanofi: Honoraria; Takeda: Honoraria, Research Funding.

Introduction: Preclincal murine models of primary and secondary hemophagocytic lymphohistiocytosis (HLH) have demonstrated the role of JAK/STAT signaling in propagating the cytokine-mediated hyperinflammatory state. Das et al. (Blood 2016) demonstrated that ruxolitinib (rux) effectively attenuates murine HLH, and Albeituni et al. (Blood 2019) found it superior to IFN-γ inhibition (the target of emapalumab-lzsg). A few single case reports exist in which rux was used for salvage therapy, however they report only limited clinical success and/or were used as a bridge to allogeneic stem cell transplantation. Here we present a series of three consecutive cases in which rux was employed as either salvage therapy for relapsed/refractory secondary HLH or front-line for moderate HLH manifestations. Importantly, each patient was maintained on a taper of rux which prevented recurrence and obviated the need for allogeneic transplantation. Two of the three patients have been tapered completely off rux without recurrence of either laboratory or clinical manifestations of HLH at the time of this submission. Case 1: Patient 1 is a 24 yo woman who had initially presented to an outside hospital with jaundice and was found to have a warm AIHA. She was initially started on steroids, but developed worsening anemia, fever, splenomegaly, and encephalopathy. On transfer to us she had ferritin of 58,505 ng/ml. Her bone marrow biopsy demonstrated abundant hemophagocytosis (Fig. 1B,C). She met HLH criteria and was started on HLH-94 protocol; however, her total and direct bilirubin climbed dramatically, peaking at 95.2 and 82.0 mg/dl, respectively. Rux 5mg BID was initiated as salvage therapy, and within 48 hours, her labs significantly improved, her fevers resolved, and she became responsive to blood transfusions (Fig. 1A). After two weeks on rux, she developed recurrent hemolysis. Her dose was increased to 20mg BID, resulting in a complete resolution of her hemolysis, fevers, transaminitis and hyperbilirubinemia. After 3 months of clinical stability, rux was tapered. She has been off rux now for three months. Case 2: Patient 2 is a 26 yo woman who presented with unremitting fevers and myalgias, and was found to have an acute hepatitis C infection. Her ferritin was 24,023ng/ml, and a bone marrow biopsy demonstrated abundant hemophagocytosis. She initially responded to the HLH-94 protocol; however, attempts to hold treatment following induction were met with recurrent fevers, encephalopathy, and hyperferritinemia. She transferred to us, and a repeat bone marrow biopsy demonstrated persistent hemophagocytosis (Fig. 2B,C), while her ferritin was 15,073 ng/ml. We initiated salvage treatment with rux 10mg BID. Her fevers, encephalopathy, and lab abnormalities quickly improved; her ferritin fell to 2,973ng/ml within 3 days (Fig. 2A). A small subsequent elevation in her ferritin prompted an increase of the rux to 20mg BID. She improved and was discharged on rux maintenance at 20mg BID. Since discharge, she remains asymptomatic with mildly elevated ferritin levels, mild pancytopenia, and is tolerating a slow wean of rux without incident. Case 3: Patient 3 is a 40 yo man with a diagnosis of hairy cell leukemia who received 5 days of cladribine. He developed febrile neutropenia 2 days following the end of chemotherapy. His infectious workup was negative with the exception of a positive peripheral blood EBV DNA PCR. He developed a mononucleosis-like syndrome, with persistent high fevers, splenomegaly, and hyperferritinemia to 6684 ng/ml. He also developed hepatic dysfunction with a direct hyperbilirubinemia peaking at 14.1 mg/dl and coagulopathy. He was treated initially with dexamethasone without resolution. A bone marrow biopsy demonstrated abundant hemophagocytosis (Fig. 3B,C). Given modest manifestations and concern that chemotherapy would exacerbate his immunosuppression, rux was initiated at 10mg BID. The liver dysfunction rapidly improved, and fevers resolved within 3 days (Fig. 3A). All other manifestations resolved within 1 week, and he was able to taper and discontinue rux within 2 months. Conclusions: The preclinical data by Albeituni et al. coupled with our clinical observations suggest that ruxolitinib may be a viable alternative to aggressive chemotherapy regimens such as HLH-94 or anti-IFN-γ (emapalumab-lzsg) therapy for HLH, and clinical trials should be considered. Disclosures DiPersio: Karyopharm Therapeutics: Consultancy; Cellworks Group, Inc.: Membership on an entity's Board of Directors or advisory committees; NeoImmune Tech: Research Funding; Macrogenics: Research Funding, Speakers Bureau; Bioline Rx: Research Funding, Speakers Bureau; RiverVest Venture Partners Arch Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees; Magenta Therapeutics: Equity Ownership; WUGEN: Equity Ownership, Patents & Royalties, Research Funding; Amphivena Therapeutics: Consultancy, Research Funding; Incyte: Consultancy, Research Funding; Celgene: Consultancy. OffLabel Disclosure: Ruxolitinib was used off-label for the treatment of Hemophagocytic Lymphohistiocytosis (HLH) in the relapsed/refractory setting and in a patient who was unable to tolerate standard therapy. This was not in a clinical trial, but reported as a case series

Introduction: Inositol-requiring enzyme 1α (IRE1α) is one of three principal transmembrane sensors in the endoplasmic reticulum (ER) involved in regulating the unfolded protein response (UPR). It splices X-box protein 1 (XBP1) mRNA yielding a transcription factor intimately involved in the plasma cell differentiation and proliferation. The IRE1α-XBP1 axis exhibits positive feedback functions that promote the pro-survival UPR and allows plasma cells to survive the high biosynthetic burden of immunoglobulin production, although IRE1α also has functions that promote cell death depending on the chronicity and severity of ER stress. Functional IRE1α has been identified as critical for in vitro cytotoxicity of bortezomib by Leung-Hagesteijn et al. (Cancer Cell 2013), with loss of IRE1α leading to in vitro resistance to proteasome inhibition. However, Mimura et al (Blood 2012) identified in vitro synergy with IRE1α-inhibition and bortezomib, and Papandeou et al. (Blood 2011) identified in vitro and in vivo anti-myeloma activity of a different IRE1α endonuclease inhibitor. The clinical implications of IRE1α are still poorly understood. In this study, we sought to identify associations between IRE1α mRNA expression (the level at which it is principally regulated) with treatment resistance and patient outcomes. Methods: We performed a secondary analysis of data from the MMRF CoMMpass study (IA14). In the CoMMpass study, RNAseq on CD138-enriched bone marrow cells was performed using Illumina TruSeq RNA library kits. Cox Regression analysis was used to compare the association of IRE1α expression with progression-free and overall survival. To determine if IRE1α expression is modulated following disease progression, we also identified patients who had pre- and post-treatment RNAseq data. We analyzed expression of IRE1α from the pre- and post-treatment specimens using paired T-tests comparing patients who had relapsed disease (relapse following completion of therapy) and refractory disease (progression on or within 60 days of completing therapy). Results: We included 768 patients who had IRE1α expression data at myeloma diagnosis. The median age was 63 (range 27-93) and 50% were male. Thirty percent of patients (n = 231) were considered to have high IRE1a expression at myeloma diagnosis. High IRE1α expression was associated with worse clinical outcome. Those with high expression had a 37% (aHR 1.37; 95% CI 1.10-1.72; p = 0.006) increase hazard for progression and a 55% (aHR 1.55; 95% CI 1.13-2.15; p = 0.008) increase hazard for death. We then identified 46 patients who had pre- and post-treatment RNAseq data. Twenty-two had relapsed disease while off of treatment and 24 had developed refractory disease while on treatment. Patients who had refractory disease were noted to have a significant decrease in the expression of IRE1α (p = 0.008). This was similar when we performed subset analysis of patients who were refractory to PI-based treatments (n=8; p = 0.044) and IMID-based treatments (n = 13; p = 0.054). In contrast, there was not a significant difference between pre-treatment and post-treatment IRE1α in relapsed disease (p = 0.312). Expression of other UPR elements, specifically PERK and XBP1, was not significantly downregulated in relapsed or refractory disease. Conclusion: Our study demonstrates that high expression of IRE1α at diagnosis is associated with worse outcomes, but that resistance to therapy is associated with a significant decrease in IRE1α expression. While this seems counterintuitive, it highlights the complex nature of the UPR and the roles of IRE1α. More aggressive/proliferative disease relies heavily on an adapted pro-survival UPR, highlighted by increased expression of IRE1α de novo. However, IRE1α has previously been demonstrated to be required for anti-myeloma activity of novel therapies; potentially either by clonal selection, dynamic alterations in UPR signaling, or epigenetic modifications, treatment-refractory myeloma cells downregulate the expression of IRE1α, a phenomenon not seen in those who completed treatment but subsequently relapsed. IRE1α inhibition could initially potentiate the clinical effects of novel therapies in a higher-risk population, but may also promote later resistance to them. Importantly, IRE1α could serve as a prognostic biomarker for risk-stratification at diagnosis as well as one predictive of impending resistance to therapy. Disclosures Fiala: Incyte: Research Funding. Wildes:Janssen: Research Funding; Carevive: Consultancy. Vij:Takeda: Honoraria, Research Funding; Sanofi: Honoraria; Karyopharm: Honoraria; Bristol-Myers Squibb: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Genentech: Honoraria; Janssen: Honoraria. Stockerl-Goldstein:AbbVie: Equity Ownership; Abbott: Equity Ownership.