Human IL-6 fosters long-term engraftment of patient-derived disease-driving myeloma cells in immunodeficient mice.

Multiple myeloma is a largely incurable and life-threatening malignancy of antibody-secreting plasma cells. An effective and widely available animal model that recapitulates human myeloma and related plasma cell disorders is lacking. We show that busulfan-conditioned human IL-6-transgenic (hIL-6-transgenic) NSG (NSG+hIL6) mice reliably support the engraftment of malignant and premalignant human plasma cells, including from patients diagnosed with monoclonal gammopathy of undetermined significance, pre- and postrelapse myeloma, plasma cell leukemia, and amyloid light chain amyloidosis. Consistent with human disease, NSG+hIL6 mice engrafted with patient-derived myeloma cells developed serum M spikes, and a majority developed anemia, hypercalcemia, and/or bone lesions. Single-cell RNA sequencing showed nonmalignant and malignant cell engraftment, the latter expressing a wide array of mRNAs associated with myeloma cell survival and proliferation. Myeloma-engrafted mice given CAR T cells targeting plasma cells or bortezomib experienced reduced tumor burden. Our results establish NSG+hIL6 mice as an effective patient-derived xenograft model for study and preclinical drug development of multiple myeloma and related plasma cell disorders.

Harmonizing definitions for hematopoietic recovery, graft rejection, graft failure, poor graft function, and donor chimerism in allogeneic hematopoietic cell transplantation: a report on behalf of the EBMT, ASTCT, CIBMTR, and APBMT.

Despite emergence of novel therapies to treat hematologic malignancies, allogeneic hematopoietic cell transplantation (allo-HCT) remains an essential treatment modality capable of curing these diseases. Allo-HCT has been also shown to be curative in benign hematologic disorders such as aplastic anemia, sickle cell disease, and thalassemia, among others. Recently, the American Society for Transplantation and Cellular Therapy (ASTCT) published standardized definitions for hematopoietic recovery, graft rejection, graft failure, poor graft function, and donor chimerism. To attempt broader international consensus, a panel of adult and pediatric physician transplant experts was assembled from European Society for Blood and Marrow Transplantation (EBMT), ASTCT, the Center for International Blood and Marrow Transplant Research (CIBMTR), and Asia-Pacific Blood and Marrow Transplantation (APBMT). Consensus was defined as ≥70% of voting members strongly agreeing or somewhat agreeing with a definition. With few exceptions, there was a consensus to endorse the prior ASTCT definitions. Importantly, we revised existing EBMT and CIBMTR data collection forms to align with these harmonized definitions that will facilitate research and international collaboration among transplant researchers and across transplant registries.

Human IL-6 fosters long-term engraftment of patient derived disease-driving myeloma cells in immunodeficient mice.

Multiple myeloma is a largely incurable and life-threatening malignancy of antibody-secreting plasma cells. An effective and widely available animal model that recapitulates human myeloma and related plasma cell disorders is lacking. We show that busulfan-conditioned hIL-6 transgenic NSG mice (NSG+hIL6) reliably support the engraftment of malignant and pre-malignant human plasma cells including from patients diagnosed with monoclonal gammopathy of undetermined significance, pre- and post-relapse myeloma, plasma cell leukemia, and AL amyloidosis. Consistent with human disease, NSG+hIL6 mice engrafted with patient-derived myeloma cells, developed serum M spikes, and a majority developed anemia, hypercalcemia, and/or bone lesions. Single cell RNA sequencing showed non-malignant and malignant cell engraftment, the latter expressing a wide array of mRNAs associated with myeloma cell survival and proliferation. Myeloma engrafted mice given CAR T-cells targeting plasma cells or bortezomib experienced reduced tumor burden. Our results establish NSG+hIL6 mice as an effective patient derived xenograft model for study and preclinical drug development of multiple myeloma and related plasma cell disorders.

Symptom clusters and their impact on quality of life in multiple myeloma survivors: Secondary analysis of BMT CTN 0702 trial.

Autologous haematopoietic cell transplantation (autoHCT) and continuous post-transplant maintenance therapy are the standard of care in transplant-eligible multiple myeloma (MM) patients. We sought to describe symptom burden and identify symptom clusters occurring in MM patients after autoHCT using data from the BMT CTN 0702 randomized controlled trial comparing the outcomes of three treatment interventions after an autoHCT in 758 MM patients. We analysed individual transplant-related symptoms assessed via the FACT-BMT questionnaire at enrolment and annually for 4-year post-autoHCT. We also described the effect the individual symptoms and symptom clusters have on quality of life (QoL). We identified three stable symptom clusters: malaise symptom cluster (lack of energy, feeling ill, having pain, experiencing nausea, loss of appetite), physical symptom cluster (having skin problems, tremors, worsening eyesight, change in taste, shortness of breath, frequent colds) and emotional symptom cluster (feeling sad, being nervous, experiencing sleep problems). Malaise and emotional symptom clusters have a greater impact on QoL than the physical symptoms cluster. Identifying these symptoms warrant additional support in terms of psychosocial support, in addition to treatment of the physical symptoms themselves.

Impact of Visceral Obesity on Clinical Outcome and Quality of Life for Patients with Multiple Myeloma: A Secondary Data Analysis of STaMINA (BMT CTN 0702) Trial.

Obesity is a common health problem in patients with multiple myeloma (MM) that has been linked to poor clinical outcomes and quality of life (QoL). We conducted a secondary analysis of the BMT CTN 0702, a randomized, controlled trial comparing outcomes of 3 treatment interventions after a single hematopoietic cell transplantation (HCT) (n = 758), to investigate the impact of visceral obesity, as measured by waist-to-hip ratio (WHR), on clinical outcomes and QoL in MM patients. A total of 549 MM patients, median age 55.5 years, were enrolled in the study. The majority of patients received triple-drug antimyeloma initial therapy before enrollment, and 29% had high-risk disease according to cytogenetic assessment. The median duration of follow-up was 6 years. There was no significant association between WHR and progression-free survival (PFS) or overall survival (OS) in MM patients undergoing HCT. Similarly, body mass index (BMI) did not significantly predict PFS or OS. Furthermore, there was no significant correlation between WHR and QoL measures. This study suggests that visceral obesity, as measured by WHR, might not have a significant impact on clinical outcomes in MM patients undergoing HCT. These findings add to the existing literature on the topic and provide valuable information for healthcare professionals and MM patients. Further studies are needed to confirm these results and to investigate other potential factors that may affect clinical outcomes and QoL in this patient population using modern imaging technologies to assess visceral obesity.

Characterization of the calcineurin inhibitor pain syndrome in patients undergoing allogeneic hematopoietic cell transplantation.

Calcineurin inhibitor pain syndrome (CIPS) is a rare complication of graft-vs-host disease prophylaxis following allogeneic hematopoietic cell transplant (alloHCT). CIPS presents as severe bilateral lower extremity pain, and the incidence, risk factors, and management of CIPS are poorly characterized.This is a single center retrospective study of patients who received tacrolimus (TAC) following alloHCT to describe the characteristics and management of CIPS and compare to a cohort who did not develop CIPS.Fifteen of 585 alloHCT patients (2.6%) developed CIPS at a median of 5 days following TAC initiation and a median level of 10.5 ng/mL. Severe bilateral foot, ankle, or leg pain were the primary symptoms. Patients with CIPS were younger and more frequently received myeloablative conditioning and total body irradiation compared to patients without CIPS. Analgesic regimens included dihydropyridine calcium channel blockers, gabapentinoids, topical diclofenac, and opioids.Clinicians should be aware of this uncommon but severe adverse effect.

T cell lymphoma and secondary primary malignancy risk after commercial CAR T cell therapy.

We report a T cell lymphoma (TCL) occurring 3 months after anti-CD19 chimeric antigen receptor (CAR) T cell immunotherapy for non-Hodgkin B cell lymphoma. The TCL was diagnosed from a thoracic lymph node upon surgery for lung cancer. The TCL exhibited CD8+ cytotoxic phenotype and a JAK3 variant, while the CAR transgene was very low. The T cell clone was identified at low levels in the blood before CAR T infusion and in lung cancer. To assess the overall risk of secondary primary malignancy after commercial CAR T (CD19, BCMA), we analyzed 449 patients treated at the University of Pennsylvania. At a median follow-up of 10.3 months, 16 patients (3.6%) had a secondary primary malignancy. The median onset time was 26.4 and 9.7 months for solid and hematological malignancies, respectively. The projected 5-year cumulative incidence is 15.2% for solid and 2.3% for hematological malignancies. Overall, one case of TCL was observed, suggesting a low risk of TCL after CAR T.

Preconditioning Frailty Phenotype Influences Survival and Relapse for Older Allogeneic Transplantation Recipients.

Hematologic malignancies disproportionately affect older adults. Hematopoietic cell transplantation (HCT) is potentially curative, but poor overall survival (OS) has limited its use in older adults. Fried's frailty phenotype (FFP) is a geriatric assessment tool that combines objective and subjective performance measures: gait speed, grip strength, activity level, exhaustion, and weight loss. People meeting ≥3 criteria are classified as frail; 1 or 2 criteria, as pre-frail; and 0 criteria, as fit. To evaluate the association of pre-HCT FFP with post-HCT outcomes, we assessed FFP prior to conditioning for 280 HCT recipients age ≥60 years with acute leukemia or a myeloid neoplasm at 3 institutions. When analyzing survival by age group, patients age ≥70 years had inferior OS compared to patients age 60 to 69 years (P = .002), with corresponding OS estimates of 38.9% (95% confidence interval [CI], 27.8% to 49.9%) and 59.3% (95% CI, 51.9% to 65.9%). Nonrelapse mortality (NRM) also was significantly higher in the older patients (P = .0005); the 2-year cumulative incidences of NRM were 38.5% (95% CI, 27.5% to 49.2%) and 17.2% (95% CI, 12.3% to 22.8%), for older and younger recipients, respectively. The cumulative incidences of relapse did not differ by age group (P = .3435). Roughly one-third (35.5%) of the patients were fit, 57.5% were pre-frail, and 7.5% were frail, with corresponding 2-year OS estimates of 68.4% (95% CI, 57.9% to 76.8%), 45.5% (95% CI, 37.4% to 53.2%), and 45.8% (95% CI, 23.4% to 65.8%) (P = .013). FFP was not significantly associated with NRM, but being frail or pre-frail was associated with a higher rate of disease-related deaths (33.3% and 27.3%, respectively, compared with 17.4% for fit patients; P = .043). In univariate modeling of restricted mean survival time with a 3-year horizon (RMST_3y), the factors that were significantly associated were FFP, age, Karnofsky Performance Status (KPS), Disease Risk Index (DRI), and HCT-specific Comorbidity Index (HCT-CI). Of those factors, only FFP (P = .006), age (P = .006), KPS (P = .004), and DRI (P = .005) were significantly associated in multivariate modeling of RMST_3y. Estimates of RMST_3y were computed and 5 risk-groups were created with survival ranging from 31.4 months for those who were age 60 to 69 years, fit, had KPS 90 to 100, and low/intermediate-risk DRI compared to 10.5 months for those who had high-risk features for all the evaluated factors. In univariate and multivariate analyses for restricted mean time to relapse with a 3-year horizon (RMRT_3y), FFP (pre-frail versus fit, P = .007; frail versus fit, P = .061) and DRI (P = .001) were the only significant factors. Predicted RMRT_3y was longest (30.6 months) for those who were fit and had low/intermediate-risk DRI scores and shortest (19.1 months) for those who were frail and had high-risk or very high-risk DRI scores. Both age and FFP impact survival after HCT. Incorporation of FFP into pre-HCT evaluations may improve decision-making and counseling regarding HCT risk for older adults. Our findings support future trials designed to reverse frailty, such as pre-HCT supervised exercise programs, and correlative analyses to unravel the connection of frailty and relapse to generate future targets for intervention. Finally, exploration of novel HCT platforms to reduce relapse in pre-frail and frail patients, as well as reduce NRM in adults age >70 years, are warranted.

Chimeric Antigen Receptor T Cells in the Treatment of Multiple Myeloma.

Chimeric antigen receptor T cells (CARTs) represent another powerful way to leverage the immune system to fight malignancy. Indeed, in multiple myeloma, the high response rate and duration of response to B cell maturation antigen-targeted therapies in later lines of disease has led to 2 Food and Drug Administration (FDA) drug approvals and opened the door to the development of this drug class. This review aims to provide an update on the 2 FDA-approved products, summarize the data for the most promising next-generation multiple myeloma CARTs, and outline current challenges in the field and potential solutions.

Mitigation of chromosome loss in clinical CRISPR-Cas9-engineered T cells.

CRISPR-Cas9 genome editing has enabled advanced T cell therapies, but occasional loss of the targeted chromosome remains a safety concern. To investigate whether Cas9-induced chromosome loss is a universal phenomenon and evaluate its clinical significance, we conducted a systematic analysis in primary human T cells. Arrayed and pooled CRISPR screens revealed that chromosome loss was generalizable across the genome and resulted in partial and entire loss of the targeted chromosome, including in preclinical chimeric antigen receptor T cells. T cells with chromosome loss persisted for weeks in culture, implying the potential to interfere with clinical use. A modified cell manufacturing process, employed in our first-in-human clinical trial of Cas9-engineered T cells (NCT03399448), reduced chromosome loss while largely preserving genome editing efficacy. Expression of p53 correlated with protection from chromosome loss observed in this protocol, suggesting both a mechanism and strategy for T cell engineering that mitigates this genotoxicity in the clinic.

Understanding Infection Risk with Anti-BCMA Bispecific Antibodies.

SUMMARY: Lancman and colleagues find that infection risk in patients treated with anti-BCMA bispecific antibodies for relapsed/refractory multiple myeloma is associated with severe immunoglobulin deficiency and may be mitigated by immunoglobulin replacement therapy. The study has implications for managing infection risk and raises questions about the optimal duration of treatment with these potent, novel immunotherapies. See related article by Lancman et al., p. 440 (4) .

One versus two sets of busulfan therapeutic drug monitoring in myeloablative allogeneic hematopoietic cell transplant.

INTRODUCTION: Busulfan is a common component of allogeneic hematopoietic cell transplant (alloHCT) conditioning, however interpatient pharmacokinetic variability can result in enhanced toxicity or increased relapse risk. Therapeutic drug monitoring (TDM) can minimize variability, yet the optimal frequency of TDM is unknown. We compared outcomes for patients with one versus two sets of busulfan TDM during myeloablative conditioning (MAC) prior to alloHCT. METHODS: We analyzed the impact of busulfan TDM frequency and dose adjustments, with the primary outcome being relapse-free survival (RFS). Other outcomes included the incidence of acute and chronic graft versus host disease (GVHD), oral mucositis, pulmonary toxicity, sinusoidal obstruction syndrome (SOS), the cumulative incidence of relapse (CIR), and overall survival (OS). RESULTS: Twenty-two patients underwent one set of sampling while 53 patients underwent two sets. Similar baseline characteristics were observed between the groups. There were no significant differences observed in RFS by day +180 (77.3% vs. 79.2%, p = 1.0), CIR by day +180 (18.2% vs. 17.8%, p = 0.74), or OS (p = 0.73). The incidences of acute GVHD, chronic GVHD, SOS, and severe mucositis were also similar. In each group, 63% received busulfan dose adjustments after one set, with 52.8% receiving further dose adjustments following the second set. CONCLUSION: We observed no significant difference in alloHCT outcomes between patients who underwent one versus two sets of busulfan TDM sampling, suggesting that a single-time TDM and dose adjustment may be adequate to maximize outcomes after MAC alloHCT.

Real-world effectiveness of intensive chemotherapy with 7&3 versus venetoclax and hypomethylating agent in acute myeloid leukemia.

Intensive chemotherapy with cytarabine and anthracycline (7&3) remains the standard therapy for patients medically fit for induction, but the assessment of fitness remains controversial. Venetoclax and hypomethylating agent (ven/HMA) combination therapy has improved outcomes in unfit patients but no prospective study has assessed ven/HMA versus 7&3 as initial therapy in older, fit patients. Given no studies and expectation of ven/HMA use in patients outside of trial criteria, we evaluated retrospective outcomes among newly diagnosed patients. A nationwide electronic health record (EHR)-derived database and the University of Pennsylvania EHR identified 312 patients receiving 7&3 and 488 receiving ven/HMA who were 60-75 years old without history of organ failure. Ven/HMA patients were older and more likely to have secondary AML, adverse cytogenetics, and adverse mutations. Median overall survival (OS) for patients receiving intensive chemotherapy was 22 versus 10 months for ven/HMA (HR 0.53, 95% CI 0.40-0.60). Controlling for measured baseline characteristic imbalances reduced survival advantage by half (HR 0.71, 95% CI 0.53-0.94). A sub-group of patients with equipoise, likelihood at least 30%-70% of receiving either treatment, had similar OS outcomes (HR 1.10, 95% CI 0.75-1.6). Regarding safety outcomes, 60-day mortality was higher for ven/HMA (15% vs. 6% at 60 days) despite higher documented infections and febrile neutropenia for 7&3. In this multicenter real-word dataset, patients selected for intensive chemotherapy had superior OS but a large group had similar outcomes with ven/HMA. Prospective randomized studies, controlling for both measured and unmeasured confounders, must confirm this outcome.

Patient Perceptions of CAR-T Therapy in the USA: Findings from In-Depth Interviews.

INTRODUCTION: Chimeric antigen receptor-T cell (CAR-T) therapy has revolutionized advanced blood cancer treatment. However, preparation, administration, and recovery from these therapies can be complex and burdensome to patients and their care partners. Utilization of an outpatient setting for CAR-T therapy administration could help improve convenience and quality of life. METHODS: In-depth qualitative interviews were conducted with 18 patients in the USA with relapsed/refractory multiple myeloma or relapsed/refractory diffuse large B-cell lymphoma, 10 of whom had completed investigational or commercially approved CAR-T therapy and 8 of whom had discussed it with their physicians. We aimed to better understand inpatient experiences and patient expectations regarding CAR-T therapy and to ascertain patient perspectives on the possibility of outpatient care. RESULTS: CAR-T offers unique treatment benefits, particularly high response rates with an extended treatment-free period. All study participants completing CAR-T were very positive about their inpatient recovery experience. Most reported mild-to-moderate side effects; two experienced severe side effects. All said that they would opt to undergo CAR-T therapy again. Participants felt that the primary advantage of inpatient recovery was immediate access to care and on-going monitoring. Perceived advantages of the outpatient setting were comfort and familiarity. Because immediate access to care was seen as crucial, patients recovering in an outpatient setting would seek either a direct contact person or phone line for assistance if needed. CONCLUSION: As institutions become more experienced with CAR-T therapies, outpatient care may help reduce financial strain. Patient input can help institutions improve the outpatient experience and ensure safety and effectiveness of CAR-T programs.

Survival Outcomes for Patients with Relapsed/ Refractory Aggressive B Cell Lymphomas Following Receipt of High-Dose Chemotherapy/Autologous Stem Transplantation and/or Chimeric Antigen Receptor-Modified T Cells.

Patients diagnosed with relapsed/refractory (R/R) diffuse large B cell lymphoma (DLBCL) or high-grade B cell lymphoma (HGBL) may achieve prolonged survival following receipt of high-dose chemotherapy/autologous stem cell transplantation (HDC/ASCT) or CD19-directed chimeric antigen receptor modified T cell therapy (CART19). Although early results from randomized clinical trials suggest that assignment to CART19 versus salvage immunochemotherapy as second-line therapy results in improved survival, analysis of a large series of patients who actually received HDC/ASCT or CART19 has yet to be performed. Such an analysis may inform future research efforts to optimize the risk stratification of R/R DLBCL/HGBL patients who are candidates for either therapy. The aim of this study was to evaluate clinicopathologic factors predictive of freedom from treatment failure (FFTF) for R/R DLBCL/HGBL patients following receipt of HDC/ASCT or CART19, and to compare patterns of treatment failure (TF) in R/R DLBCL/HGBL patients receiving HDC/ASCT and those receiving CART19. THE STUDY GROUP COMPRISED: patients age ≤75 years with R/R DLBCL/HGBL who received HDC/ASCT demonstrating partial or complete metabolic response to salvage immunochemotherapy and/or CART19 in the standard of care setting at the University of Pennsylvania between 2013 and 2021. Survival analyses were performed from the time of infusion of either HDC/ASCT or CART19, as well as at landmark time points postinfusion for patients who achieved FFTF. For 100 HDC/ASCT patients with a median follow-up of 62.7 months, the estimated 36-month FFTF and overall survival (OS) rates were 59% and 81%, respectively. For 109 CART19 patients with a median follow-up of 37.6 months, the estimated 36-month FFTF and OS rates were 24% and 48%, respectively. HDC/ASCT patients had significantly higher rates of estimated 36-month FFTF when they achieved actual FFTF at 3, 6, 12 and 24 months. Additionally, the rates of baseline characteristics predictive of TF at 36 months for either HDC/ASCT or CART19 patients were either similar to or significantly lower for CART19 patients compared to HDC/ASCT patients who achieved actual FFTF at 3, 6, 12, and 24 months. Patients with R/R DLBCL/HGBL achieving response to salvage immunochemotherapy who received HDC/ASCT had a high rate of estimated FFTF regardless of whether they harbored features predictive of resistance to salvage immunochemotherapy, which may be more durable than that of R/R DLBCL/HGBL patients receiving CART19. These findings support further investigation of disease characteristics, such as molecular features, that may predict response to salvage immunochemotherapy in patients fit for HDC/ASCT.

Mitigation of chromosome loss in clinical CRISPR-Cas9-engineered T cells.

CRISPR-Cas9 genome editing has enabled advanced T cell therapies, but occasional loss of the targeted chromosome remains a safety concern. To investigate whether Cas9-induced chromosome loss is a universal phenomenon and evaluate its clinical significance, we conducted a systematic analysis in primary human T cells. Arrayed and pooled CRISPR screens revealed that chromosome loss was generalizable across the genome and resulted in partial and entire loss of the chromosome, including in pre-clinical chimeric antigen receptor T cells. T cells with chromosome loss persisted for weeks in culture, implying the potential to interfere with clinical use. A modified cell manufacturing process, employed in our first-in-human clinical trial of Cas9-engineered T cells, 1 dramatically reduced chromosome loss while largely preserving genome editing efficacy. Expression of p53 correlated with protection from chromosome loss observed in this protocol, suggesting both a mechanism and strategy for T cell engineering that mitigates this genotoxicity in the clinic.

Adapting the HCT-CI Definitions for Children, Adolescents, and Young Adults with Hematologic Malignancies Undergoing Allogeneic Hematopoietic Cell Transplantation.

Allogeneic hematopoietic cell transplantation is a curative procedure for hematologic malignancies but is associated with a significant risk of non-relapse mortality (NRM). The Hematopoietic Cell Transplantation-Comorbidity Index (HCT-CI) is a prognostic tool that discriminates this risk in all age groups. A recent survey of transplant physicians demonstrated that 79% of pediatric providers used the HCT-CI infrequently, and most reported concerns about its applicability in the younger population. We conducted a retrospective study using the Center for International Blood and Marrow Transplant Research database to examine the impact of expanded HCT-CI definitions on NRM in pediatric and young adult patients with hematologic malignancies. We included 5790 patients <40 years old receiving allogeneic transplants between 2008 and 2017 to examine broader definitions of comorbidities in the HCT-CI, including history of mechanical ventilation and fungal infection, estimated glomerular filtration rate, and body mass index (BMI) percentiles. Multivariable Fine-Gray models were created to determine the effect of each HCT-CI defining comorbidity and its modification on NRM and were used to develop 2 novel risk scores. We next developed the expanded HCT-CI for children and young adults (youth with malignancies; expanded ymHCT-CI), where 23% patients had an increased comorbidity score, compared to the HCT-CI. Comorbidities with hazard ratio < 1.2 were then removed to create the simplified HCT-CI for children and young adults (youth with malignancies; simplified ymHCT-CI), which demonstrated higher scores corresponded to a greater risk of NRM (P < .001). These novel comorbidity indexes with broader definitions are more relevant to pediatric and young adult patients, and prospective studies are needed to validate these in the younger patient population. It remains to be seen whether the development of these pediatric-specific and practical risk indexes increases their use by the pediatric transplant community.

Progressive multifocal leukoencephalopathy in multiple myeloma.

Progressive multifocal leukoencephalopathy (PML) is a rare and often fatal demyelinating disease of the central nervous system caused by reactivation of the JC virus in the context of immune suppression such as HIV, malignancy, and certain immunomodulatory medications. PML has been reported only rarely in multiple myeloma patients, and its presenting features and natural history in this population are not well known. We describe six cases of PML among multiple myeloma patients treated at our institution between 2013 and 2022, including two that developed on or shortly after treatment with recently developed BCMA-directed immunotherapies.

A Multicenter Phase II, Double-Blind, Placebo-Controlled Trial of Maintenance Ixazomib After Allogeneic Transplantation for High-Risk Multiple Myeloma: Results of the Blood and Marrow Transplant Clinical Trials Network 1302 Trial.

The role of allogeneic hematopoietic cell transplantation (allo-HCT) followed by maintenance therapy in high-risk multiple myeloma (MM) remains controversial. We evaluated the efficacy of ixazomib maintenance therapy after reduced-intensity conditioning allo-HCT from HLA-matched donors in patients with high-risk MM. The primary study endpoint was progression-free survival (PFS) postrandomization, treated as a time to event. Secondary endpoints were grade II-IV and grade II-IV acute graft-versus-host-disease (GVHD), chronic GVHD, best response, disease progression, nonrelapse mortality (NRM), overall survival (OS), toxicity, infection, and health-related quality of life. In this phase 2, double-blinded, prospective multicenter trial, we randomized patients with high-risk MM (ie, those with poor-risk cytogenetics, plasma cell leukemia, or relapsing within 24 months after autologous HCT) to ixazomib (3 mg on days 1, 8, and 15) or placebo after allo-HCT. The conditioning regimen included fludarabine/melphalan/bortezomib with tacrolimus plus methotrexate for GVHD. Fifty-seven patients were enrolled, of whom 52 (91.2%) underwent allo-HCT and 43 (82.7%) were randomized to ixazomib versus placebo. At 21 months postrandomization, the ixazomib and placebo groups had similar PFS (55.3% versus 59.1%; P = 1.00) and OS (94.7% versus 86.4%; P = .17). The cumulative incidences of grade III-IV acute GVHD at 100 days (9.5% versus 0%) and chronic GVHD at 12 months (68.6% versus 63.6%) also were similar in the 2 groups. The secondary analysis showed that at 24 months post-allo-HCT, PFS and OS were 52% and 82%, respectively, with a corresponding NRM of 11.7%. These results demonstrate the safety and durable disease control with allo-HCT in high-risk MM patients. We could not adequately assess the efficacy of ixazomib maintenance because the trial terminated early owing to enrollment delays, but there was no indication of any impact on outcomes.