International Myeloma Working Group immunotherapy committee consensus guidelines and recommendations for optimal use of T-cell-engaging bispecific antibodies in multiple myeloma.

Multiple myeloma remains an incurable disease, despite the development of numerous drug classes and combinations that have contributed to improved overall survival. Immunotherapies directed against cancer cell-surface antigens, such as chimeric antigen receptor (CAR) T-cell therapy and T-cell-redirecting bispecific antibodies, have recently received regulatory approvals and shown unprecedented efficacy. However, these immunotherapies have unique mechanisms of action and toxicities that are different to previous treatments for myeloma, so experiences from clinical trials and early access programmes are essential for providing specific recommendations for management of patients, especially as these agents become available across many parts of the world. Here, we provide expert consensus clinical practice guidelines for the use of bispecific antibodies for the treatment of myeloma. The International Myeloma Working Group is also involved in the collection of prospective real-time data of patients treated with such immunotherapies, with the aim of learning continuously and adapting clinical practices to optimise the management of patients receiving immunotherapies.

Isatuximab plus pomalidomide and dexamethasone in patients with relapsed/refractory multiple myeloma in real-world: The retrospective IMAGE study.

BACKGROUND: IMAGE is a retrospective cohort study of patients enrolled in early access programs (EAPs) in France with relapsed/refractory multiple myeloma (RRMM) receiving isatuximab with pomalidomide and dexamethasone (Isa-Pd). METHODS: Patients aged ≥18 years with RRMM who received ≥1 dose of Isa under the EAPs between July 29, 2019 and August 30, 2020 were included. Effectiveness endpoints included progression-free survival (PFS) and response rates. Verbatim terms for adverse events (AEs) were coded using the Medical Dictionary for Regulatory Activities and not graded for severity. RESULTS: A total of 294 and 299 patients were included in the effectiveness and safety populations, respectively. IMAGE included patients who received one prior line of treatment (10.2%) and were daratumumab-refractory (19.1%). At median follow-up of 14.2 months, median PFS in the effectiveness population was 12.4 months (95% CI 9.0-15.0). Overall response and very good partial response rates were 46.3% and 27.9%, respectively. Subgroup analyses reflected similar results. In the safety population, 26.4% of patients reported at least one AE; the most common any-grade AE was neutropenia (9.4%). CONCLUSION: IMAGE demonstrated Isa-Pd had meaningful effectiveness in median PFS and depth of response and no new safety signals in a real-world context, consistent with clinical trial results.

Plain Language Summary of the KarMMa-3 study of ide-cel or standard of care regimens in people with relapsed or refractory multiple myeloma.

WHAT IS THIS SUMMARY ABOUT?: This plain language summary describes the results of a Phase 3 study called KarMMa-3. In this ongoing study, researchers looked at a relatively new treatment for people with multiple myeloma, a type of blood cancer, whose cancer got worse despite treatment (refractory) or had cancer that at first improved with treatment, but eventually stopped responding (relapsed). HOW WAS THIS STUDY CONDUCTED?: In the KarMMa-3 study, people with relapsed or refractory multiple myeloma received either a one-time infusion of a new treatment, named ide-cel, or one of the standard of care regimens currently available for patients with this cancer. People were treated with the standard of care regimens in weekly or monthly cycles until the cancer got worse, there were unacceptable side effects, or the person withdrew from the study. WHAT WERE THE RESULTS?: The results of this study showed that people receiving the one-time infusion of ide-cel lived longer without the cancer getting worse and had a greater reduction in cancer cells than patients receiving the standard of care regimen. A higher percentage of patients receiving ide-cel responded to treatment than patients receiving the standard of care regimen, and the response to treatment was better with idecel. These results show that ide-cel is a promising treatment for this challenging disease. Clinical Trial Registration: NCT03651128 (KarMMa-3 study).

RAS/RAFlandscape in monoclonal plasma cell conditions.

Multiple Myeloma (MM) is characterized by a huge heterogeneity at the molecular level. The RAS/RAF pathway is the most frequently mutated, in about 50% of the patients. However, these mutations are frequently subclonal, suggesting a secondary event. Since these genes are part of our routine next-generation sequencing (NGS) panel, we analyzed >10,000 patients with different plasma cell disorders in order to describe the RAS/RAF landscape. In this large cohort of patients, almost 61% of the patients presented a RAS/RAF mutation at diagnosis or relapse, but much lower frequencies in pre-symptomatic cases. Of note, the mutations were different from that observed in solid tumors (higher proportions of Q61 mutations). In 29 patients with two different mutations, we were able to perform single cell sequencing, showing that in most cases, mutations occurred in different subclones, suggesting an ongoing mutational process. These findings suggest that RAS/RAF pathway is not an attractive target, both on therapeutic and residual disease assessment points of vue.

Progression-free survival as a surrogate endpoint for overall survival in patients with relapsed or refractory multiple myeloma.

OBJECTIVES: The goal of the research was to assess the quantitative relationship between median progression-free survival (PFS) and median overall survival (OS) specifically among patients with relapsed/refractory multiple myeloma (RRMM) based on published randomized controlled trials (RCTs). METHODS: Two bibliographic databases (PubMed and Embase, 1970-2017) were systematically searched for RCTs in RRMM that reported OS and PFS, followed by an updated search of studies published between 2010 and 2022 in 3 databases (Embase, MEDLINE, and EBM Reviews, 2010-2022). The association between median PFS and median OS was assessed using the nonparametric Spearman rank and parametric Pearson correlation coefficients. Subsequently, the quantitative relationship between PFS and OS was assessed using weighted least-squares regression adjusted for covariates including age, sex, and publication year. Study arms were weighted by the number of patients in each arm. RESULTS: A total of 31 RCTs (56 treatment arms, 10,450 patients with RRMM) were included in the analysis. The average median PFS and median OS were 7.1 months (SD 5.5) and 28.1 months (SD 11.8), respectively. The Spearman and Pearson correlation coefficients between median PFS and median OS were 0.80 (P < 0.0001) and 0.79 (P < 0.0001), respectively. In individual treatment arms of RRMM trials, each 1-month increase in median PFS was associated with a 1.72-month (95% CI 1.26-2.17) increase in median OS. CONCLUSION: Analysis of the relationship between PFS and OS incorporating more recent studies in RRMM further substantiates the use of PFS to predict OS in RRMM.

Round Table Discussion on Optimal Clinical Trial Design in Precursor Multiple Myeloma.

SUMMARY: While the current approach to precursor hematologic conditions is to "watch and wait," this may change with the development of therapies that are safe and extend survival or delay the onset of symptomatic disease. The goal of future therapies in precursor hematologic conditions is to improve survival and prevent or delay the development of symptomatic disease while maximizing safety. Clinical trial considerations in this field include identifying an appropriate at-risk population, safety assessments, dose selection, primary and secondary trial endpoints including surrogate endpoints, control arms, and quality-of-life metrics, all of which may enable more precise benefit-risk assessment.

MYC dependency in GLS1 and NAMPT is a therapeutic vulnerability in multiple myeloma.

Multiple myeloma (MM) is an incurable hematological malignancy in which MYC alterations contribute to the malignant phenotype. Nevertheless, MYC lacks therapeutic druggability. Here, we leveraged large-scale loss-of-function screens and conducted a small molecule screen to identify genes and pathways with enhanced essentiality correlated with MYC expression. We reported a specific gene dependency in glutaminase (GLS1), essential for the viability and proliferation of MYC overexpressing cells. Conversely, the analysis of isogenic models, as well as cell lines dataset (CCLE) and patient datasets, revealed GLS1 as a non-oncogenic dependency in MYC-driven cells. We functionally delineated the differential modulation of glutamine to maintain mitochondrial function and cellular biosynthesis in MYC overexpressing cells. Furthermore, we observed that pharmaceutical inhibition of NAMPT selectively affects MYC upregulated cells. We demonstrate the effectiveness of combining GLS1 and NAMPT inhibitors, suggesting that targeting glutaminolysis and NAD synthesis may be a promising strategy to target MYC-driven MM.

Genomic profiling of Mycosis Fungoides identifies patients at high risk of disease progression.

Mycosis fungoides (MF) is the most prevalent primary cutaneous T-cell lymphoma, with an indolent or aggressive course and poor survival. The pathogenesis of MF remains unclear, and prognostic factors in the early stages are not well-established. Here, we characterized the most recurrent genomic alterations using whole-exome sequencing of 67 samples from 48 patients from Lille University Hospital (France), including 18 sequential samples drawn across stages of the malignancy. Genomic data were analyzed on the Broad Institute's Terra bioinformatics platform. We found that gain7q, gain10p15.1 (IL2RA and IL15RA), del10p11.22 (ZEB1), or mutations in JUNB and TET2 are associated with high-risk disease stages. Furthermore, gain7q, gain10p15.1 (IL2RA and IL15RA), del10p11.22 (ZEB1), and del6q16.3 (TNFAIP3) are coupled with shorter survival. Del6q16.3 (TNFAIP3) was a risk factor for progression in low-risk patients. By analyzing the clonal heterogeneity and the clonal evolution of the cohort, we defined different phylogenetic pathways of the disease with acquisition of JUNB, gain10p15.1 (IL2RA and IL15RA), or del12p13.1 (CDKN1B) at progression. These results establish the genomics and clonality of MF and identify potential patients at risk of progression, independent of their clinical stage.

Health-related quality of life in patients with triple-class exposed relapsed and refractory multiple myeloma treated with idecabtagene vicleucel or standard regimens: patient-reported outcomes from the phase 3, randomised, open-label KarMMa-3 clinical trial.

BACKGROUND: Chimeric antigen receptor T-cell therapy idecabtagene vicleucel (ide-cel) showed significantly improved progression-free survival compared with standard regimens in adults with relapsed and refractory multiple myeloma who had received two to four previous regimens in the ongoing phase 3 KarMMa-3 trial (NCT03651128). This study analysed patient-reported outcomes (PROs), a KarMMa-3 secondary endpoint. METHODS: In the randomised, open-label, phase 3 KarMMa-3 trial, 386 patients in hospitals (≥18 years of age, with measurable disease and an Eastern Cooperative Oncology Group performance status score of 0 or 1, who had received two to four previous regimens-including an immunomodulatory agent, a proteasome inhibitor, and daratumumab-and had documented disease progression after receiving their last dose of the last therapy) were randomly assigned to ide-cel (n=254) or standard regimens (daratumumab, pomalidomide, and dexamethasone; daratumumab, bortezomib, and dexamethasone; ixazomib, lenalidomide, and dexamethasone; carfilzomib and dexamethasone; or elotuzumab, pomalidomide, and dexamethasone; n=132). Patients were expected to complete the European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life C30 Questionnaire (QLQ-C30), Multiple Myeloma Module (QLQ-MY20), EQ 5 dimensions (EQ-5D), and EQ-5D visual analogue scale (VAS) at baseline and follow-up timepoints (data cutoff April 18, 2022). PROs included nine prespecified primary domains: EORTC QLQ-C30 GHS-quality of life (QoL), physical functioning, cognitive functioning, fatigue, and pain; QLQ-MY20 disease symptoms and side effects of treatment; and five-level EQ-5D (EQ-5D-5L) index score and EQ-5D visual VAS. Differences in overall least-squares mean changes from baseline to month 20 were analysed using post-hoc constrained longitudinal data analysis. Time to confirmed improvement or deterioration from baseline was analysed using Cox proportional hazard models. FINDINGS: Patients were randomly assigned between May 6, 2019, and April 8, 2022. Overall, the median age was 63 years (IQR 55-68); 151 (39%) patients were female; and 250 (65%) patients were White, 36 (9%) Black or African American, 19 (5%) Hispanic or Latino, 12 (3%) Asian, and seven (2%) of other race. The median follow-up was 18·6 months (IQR 14·0-26·4). PRO compliance was higher than 75% throughout. Overall least-squares mean changes from baseline favoured ide-cel with Hedges' g effect sizes from 0·3 to 0·7 for most domains. Patients in the ide-cel group showed statistically significant and clinically meaningful improvements across the primary PRO domains of interest, with the exception of QLQ-MY20 disease symptoms, side effects of treatment, and EQ-5D-5L index score, which showed improvement across assessment visits but did not exceed the within-group minimally important difference thresholds. The ide-cel group had shorter times to clinically meaningful improvement than the standard regimens group in QLQ-C30 domains except in role functioning, diarrhoea, and financial difficulties; in QLQ-MY20 domains except body image; and in EQ-5D-VAS. INTERPRETATION: Ide-cel offers improved health-related quality of life compared with standard regimens for patients with relapsed and refractory multiple myeloma after previous lines of therapy. The PRO data highlight the extended QoL benefits of a one-time infusion with ide-cel compared with continuous treatment with standard regimens in the treatment of triple-class exposed patients with relapsed and refractory multiple myeloma. FUNDING: 2seventy bio and Celgene, a Bristol Myers Squibb Company.

Daratumumab, carfilzomib, lenalidomide, and dexamethasone with tandem transplant for high-risk newly diagnosed myeloma.

ABSTRACT: High-risk (HR) cytogenetics are associated with poor outcomes in newly diagnosed multiple myeloma (NDMM), and dedicated studies should address this difficult-to-treat population. The phase 2 study 2018-04 from the Intergroupe Francophone du Myelome evaluated feasibility of an intensive strategy with quadruplet induction and consolidation plus tandem transplant in HR transplant-eligible (TE) NDMM. HR cytogenetics were defined by presence of del(17p), t(4;14), and/or t(14;16). Treatment consisted of daratumumab-carfilzomib-lenalidomide-dexamethasone (D-KRd) induction, autologous stem cell transplantation (ASCT), D-KRd consolidation, second ASCT, and daratumumab-lenalidomide maintenance. The primary end point was feasibility. Fifty patients with previously untreated NDMM were included. Median age was 57. Del(17p), t(4;14), and t(14;16) were found in 40%, 52%, and 20% of patients, respectively. At data cutoff, the study met the primary end point with 36 patients completing second transplant. Twenty patients discontinued the study due to stem cell collection failure (n = 8), disease progression (n = 7), adverse event (n = 4), or consent withdrawal (n = 1). Grade 3 to 4 D-KRd induction/consolidation-related adverse events (>5% of patients) were neutropenia (39%), anemia (12%), thrombocytopenia (7%), and infection (6%). The overall response rate was 100% for patients completing second transplant, including 81% complete response. Premaintenance minimal residual disease (MRD) negativity rate (10-6) was 94%. After a median follow-up of 33 months, the 30-month progression-free survival (PFS) and overall survival were 80% and 91%, respectively. In conclusion, D-KRd with tandem transplant is feasible in patients with HR TE-NDMM and resulted in high response rates and PFS. This trial was registered at www.clinicaltrials.gov as #NCT03606577.

How I treat multiple myeloma in geriatric patients.

ABSTRACT: Multiple myeloma (MM) is primarily a disease of older patients. Until recently, geriatric aspects in the context of MM have been poorly investigated. Treatment outcomes for geriatric patients with MM are often compromised by comorbidities and an enhanced susceptibility to adverse events from therapy. Assessment of patient frailty has become more frequent and will be useful in the context of significant and continuous advances in therapy. The recent emergence of immunotherapy with CD38 monoclonal antibodies and upcoming immunooncology drugs, such as bispecific antibodies, will lead to additional therapeutic progress. The applicability of these new molecules to older and frail patients is a key clinical question. Here, we present 2 patient cases derived from clinical practice. We review current frailty scores and standards of care for older, newly diagnosed patients with MM, including frail subgroups, and discuss ways to tailor treatment, as well as treatment perspectives in this population.

Venous thromboembolism prophylaxis and multiple myeloma patients in real-life: Results of a large survey and clinical guidance recommendations from the IFM group.

Venous thromboembolism (VTE) remains a critical issue in the management of patients with multiple myeloma (MM), particularly when immunomodulatory drugs (IMiDs) combined with dexamethasone therapy are being prescribed as first-line and relapse therapy. One possible explanation for the persistent high rates of VTE, is the use of inappropriate thromboprophylaxis strategies for patients starting antimyeloma treatment. To tackle the issue, the Intergroupe francophone du myélome (IFM) offered convenient guidance for VTE thromboprophylaxis in MM patients initiating systemic therapy. This guidance is mainly supported by the results of a large survey on the clinical habits regarding VTE of physicians who are substantially involved in daily care of MM patients. VTE prophylaxis should be considered for all patients treated with IMiDs in combination with dexamethasone, in the absence of significant comorbidities, such as renal failure or bleeding risk. Anticoagulant should be preferred to antiplatelet agents for thromboprophylaxis. Despite the absence of large randomized controlled trials comparing those attitudes/options, available data on direct oral anticoagulants, which are already used in daily management of MM patients, are consistent with their potential usefulness for VTE prophylaxis in such patients. However, in order to implement a personalized continuous improvement strategy, clinicians must to be organized to collect all the data regarding this management. In other situations, thromboprophylaxis should be evaluated by using risk models and after careful evaluation of the risk/benefit ratio.

Incidence, timing, and management of infections in patients receiving teclistamab for the treatment of relapsed/refractory multiple myeloma in the MajesTEC-1 study.

BACKGROUND: Patients with relapsed/refractory multiple myeloma are at increased risk of infection. Infections during treatment with teclistamab, the first B-cell maturation antigen-directed bispecific antibody approved for triple-class-exposed relapsed/refractory multiple myeloma, was examined in the phase 1/2 MajesTEC-1 study. METHODS: Patients (N = 165) received subcutaneous teclistamab 1.5 mg/kg weekly after a step-up dosing schedule (0.06 mg/kg and 0.3 mg/kg, each separated by 2-4 days). Patients were monitored frequently for infections; prophylaxis and management were per institutional guidelines. RESULTS: At a median follow-up of 22.8 months (range, 0.3-33.6), infections were reported in 132 patients (80.0%). Grade 3/4 infections occurred in 91 patients (55.2%), including COVID-19 (21.2%), respiratory infections (19.4%), Pneumocystis jirovecii pneumonia (4.2%), viral infections (4.2%), and gastrointestinal infections (1.2%). Twenty-one patients died from infections (18 from COVID-19). Median time to first onset of any-grade and grade 3 to 5 infections was 1.7 and 4.2 months, respectively. Overall, 70.9% of patients had ≥1 postbaseline immunoglobulin G (IgG) level <400 mg/dL; median time to IgG <400 mg/dL was 1.2 months (range, 0.2-19.8) and 46.1% received ≥1 dose of IgG replacement. Grade 3/4 neutropenia occurred in 65.5% of patients (median time to grade ≥3 neutropenia/febrile neutropenia was 2.3 months [range, 0-18.1]). CONCLUSION: Based on the infection profile of B-cell maturation antigen-targeted bispecific antibodies such as teclistamab, it is recommended that clinicians and patients remain vigilant for a range of infection types throughout treatment to facilitate prompt intervention. Appropriate screening, prophylaxis, and management of infections, hypogammaglobulinemia, and neutropenia are important. CLINICAL TRIAL REGISTRATION: NCT03145181/NCT04557098 (ClinicalTrials.gov) PLAIN LANGUAGE SUMMARY: Before starting teclistamab, patients should be up to date with vaccinations (including COVID-19) and screened for hepatitis B and C and HIV. Teclistamab should not be given to patients with any active infections. Prophylactic antimicrobials should be administered per institutional guidelines. Prophylaxis for Pneumocystis jirovecii pneumonia and herpes simplex/varicella zoster virus is recommended during teclistamab treatment. Close monitoring of infections and immunoglobulin G (IgG) levels should continue throughout teclistamab treatment. IgG replacement (administered every 3-6 weeks) should be used to maintain IgG ≥400 mg/dL. Growth factors should be considered for grade ≥3 neutropenia with infection/fever and grade 4 neutropenia.

Comparative Effectiveness of Teclistamab Versus Real-World Physician's Choice of Therapy in LocoMMotion and MoMMent in Triple-Class Exposed Relapsed/Refractory Multiple Myeloma.

INTRODUCTION: Teclistamab is the first approved B cell maturation antigen × CD3 bispecific antibody with precision dosing for the treatment of triple-class exposed (TCE) relapsed/refractory multiple myeloma (RRMM). We compared the effectiveness of teclistamab in MajesTEC-1 versus real-world physician's choice of therapy (RWPC) in patients from the prospective, non-interventional LocoMMotion and MoMMent studies. METHODS: Patients treated with teclistamab from MajesTEC-1 (N = 165) were compared with an external control arm from LocoMMotion (N = 248) or LocoMMotion + MoMMent pooled (N = 302). Inverse probability of treatment weighting adjusted for imbalances in prognostic baseline characteristics. The relative effect of teclistamab versus RWPC for overall response rate (ORR), very good partial response or better (≥ VGPR) rate, and complete response or better (≥ CR) rate was estimated with an odds ratio using weighted logistic regression transformed into a response-rate ratio (RR) and 95% confidence interval (CI). Weighted proportional hazards regression was used to estimate hazard ratios (HRs) and 95% CIs for duration of response (DOR), progression-free survival (PFS), and overall survival (OS). RESULTS: Baseline characteristics were well balanced between treatment cohorts after reweighting. Patients treated with teclistamab had significantly improved outcomes versus RWPC in LocoMMotion: ORR (RR [95% CI], 2.44 [1.79-3.33]; p < 0.0001), ≥ VGPR (RR 5.78 [3.74-8.93]; p < 0.0001), ≥ CR (RR 113.73 [15.68-825.13]; p < 0.0001), DOR (HR 0.39 [0.24-0.64]; p = 0.0002), PFS (HR 0.48 [0.35-0.64]; p < 0.0001), and OS (HR 0.64 [0.46-0.88]; p = 0.0055). Teclistamab versus RWPC in LocoMMotion + MoMMent also had significantly improved outcomes: ORR (RR 2.41 [1.80-3.23]; p < 0.0001), ≥ VGPR (RR 5.91 [3.93-8.88]; p < 0.0001), ≥ CR (RR 132.32 [19.06-918.47]; p < 0.0001), DOR (HR 0.43 [0.26-0.71]; p = 0.0011), PFS (HR 0.49 [0.37-0.66]; p < 0.0001), and OS (HR 0.69 [0.50-0.95]; p = 0.0247). CONCLUSION: Teclistamab demonstrated significantly improved effectiveness over RWPC in LocoMMotion ± MoMMent, emphasizing its clinical benefit as a highly effective treatment for patients with TCE RRMM. TRIAL REGISTRATION: MajesTEC-1, ClinicalTrials.gov NCT03145181 (phase 1) and NCT04557098 (phase 2); LocoMMotion, ClinicalTrials.gov NCT04035226; MoMMent, ClinicalTrials.gov NCT05160584.

Difficult-to-treat patients with relapsed/refractory multiple myeloma: A review of clinical trial results.

Overall outcomes for multiple myeloma have improved due to the availability of new therapies, but patients with relapsed/refractory multiple myeloma harbouring certain factors continue to pose a therapeutic challenge. These challenging features include high-risk cytogenetics, renal impairment, patient characteristics such as age and frailty, and extramedullary disease. Prior refractory status and number of prior lines add further complexity to the treatment of these patients. While newer regimens are available and have suggested efficacy in these patient populations through subgroup analyses, differences in trial definitions and cut-offs make meaningful comparisons difficult. This review aims to examine the available clinical trial data for patients with high-risk cytogenetics, renal impairment, age and frailty and extramedullary disease.

Measurable Residual Disease Testing in Multiple Myeloma Routine Clinical Practice: A Modified Delphi Study.

We used a modified Delphi approach to establish areas of consensus and nonconsensus regarding the utility of determining measurable residual disease (MRD) to assess multiple myeloma (MM) treatment response, which may inform disease management and design of future clinical trials. This modified Delphi study incorporated 2 iterative rounds of surveys to evaluate the opinions of an expert panel of 61 practicing hematological oncologists from across 14 countries in Europe concerning the use of MRD testing in MM management. Survey 1 assessed experts' opinions on MRD testing in different clinical situations and associated challenges. Survey 2 focused on the lack of consensus areas identified in survey 1. Consensus to an individual question was defined a priori as 75% agreement or disagreement by the panel. From the 2 rounds of surveys, the experts reached consensus agreement that MRD testing should be performed in newly diagnosed or relapsed patients who achieved complete response (CR) or better after transplantation. In transplant-ineligible patients, experts recommended MRD testing in those who are ≤70 years old and in CR. If a patient was previously positive on positron-emission tomography and computed tomography (PET/CT), both MRD and PET/CT should be assessed at CR. MRD testing should be performed ≤6 months after transplantation and every 6-12 months in continuously treated patients in CR. There was no consensus on making treatment decisions based on MRD status. MRD testing is an important component of clinical management in MM. Additional data will further clarify the role of MRD in guiding treatment decisions.

Systematic characterization of therapeutic vulnerabilities in Multiple Myeloma with Amp1q reveals increased sensitivity to the combination of MCL1 and PI3K inhibitors.

The development of targeted therapy for patients with Multiple Myeloma (MM) is hampered by the low frequency of actionable genetic abnormalities. Gain or amplification of chr1q (Amp1q) is the most frequent arm-level copy number gain in patients with MM, and it is associated with higher risk of progression and death despite recent advances in therapeutics. Thus, developing targeted therapy for patients with MM and Amp1q stands to benefit a large portion of patients in need of more effective management. Here, we employed large-scale dependency screens and drug screens to systematically characterize the therapeutic vulnerabilities of MM with Amp1q and showed increased sensitivity to the combination of MCL1 and PI3K inhibitors. Using single-cell RNA sequencing, we compared subclones with and without Amp1q within the same patient tumors and showed that Amp1q is associated with higher levels of MCL1 and the PI3K pathway. Furthermore, by isolating isogenic clones with different copy number for part of the chr1q arm, we showed increased sensitivity to MCL1 and PI3K inhibitors with arm-level gain. Lastly, we demonstrated synergy between MCL1 and PI3K inhibitors and dissected their mechanism of action in MM with Amp1q.