Sonneveld, Pieter

Despite significant improvements in survival of patients with multiple myeloma (MM), outcomes remain heterogeneous, and a significant proportion of patients experience suboptimal outcomes. Importantly, traditional prognostic factors based on data from patients treated with older therapies no longer capture prognosis accurately in the contemporary era of novel triplet or quadruplet therapies. Therefore, risk stratification requires refinement in the context of available and investigational treatment options in routine practice and clinical trials, respectively. The current identification of high-risk MM (HRMM) in routine practice is based on the Revised International Staging System, which stratifies patients using a combination of widely available serum biomarkers and chromosomal abnormalities assessed via fluorescence in situ hybridization. In recent years, a substantial body of evidence concerning additional clinical, biological, and molecular/genomic prognostic factors has accumulated, along with new MM risk stratification tools and consensus reports. The International Myeloma Society, along with the International Myeloma Working Group, convened an Expert Panel with the primary aim of revisiting the definition of HRMM and formulating a practical and data-driven consensus definition, based on new evidence from molecular/genomic assays, updated clinical data, and contemporary risk stratification concepts. The Panel proposes the following Consensus Genomic Staging (CGS) of HRMM which relies upon the presence of at least one of these abnormalities: (1) del(17p), with a cutoff of >20% clonal fraction, and/or TP53 mutation; (2) an IgH translocation including t(4;14), t(14;16), or t(14;20) along with 1q+ and/or del(1p32); (3) monoallelic del(1p32) along with 1q+ or biallelic del(1p32); or (4) β2 microglobulin ≥5.5 mg/L with normal creatinine (<1.2 mg/dL).

PURPOSE Newly approved drugs and combinations treating multiple myeloma (MM) have resulted in substantial improvements in patients' survival. To deliver rapid access to newer therapies, an earlier end point to expedite clinical trials is needed. Our objective was to evaluate the minimal residual disease–negative complete response (MRD-CR) as an intermediate end point for progression-free survival (PFS) and overall survival (OS) in newly diagnosed (ND) transplant-eligible (NDTE) patients, ND transplant-ineligible (NDTinE) patients, and patients with relapsed/refractory (RR) MM. PATIENTS AND METHODS Individual patient data from 20 randomized multicenter trials were collected. Eleven studies (4,773 patients) with sufficient data were analyzed to evaluate whether 9- or 12-month MRD-CR classified at a 10 –5 threshold could be reasonably likely to predict the clinical benefit of new agents regarding PFS and OS. Global odds ratio (OR) was estimated using the bivariate Plackett Copula model. Supportive evaluation included correlations of the treatment effects on MRD-CR end points and PFS/OS, evaluated by both linear regression ( R 2 weighted least squared ) and Copula ( R 2 Copula ) models. RESULTS The analysis demonstrated that both 9- and 12-month MRD-CR strongly correlated with PFS at patient level in NDTE patients, NDTinE patients, and patients with RRMM. Global ORs ranged from 3.06 to 16.24, all with 95% CIs excluding 1.0. Encouraging trial-level correlations ( R 2 , 0.61-0.70) were observed by pooling three populations and were stronger ( R 2 , 0.67-0.78) in the ND population. Similar results were observed for OS. CONCLUSION Our findings provided the support for use of MRD-CR classified at a 10 –5 threshold at either 9 or 12 months after starting of the treatment, as an intermediate end point to support accelerated approvals, in future trials in NDTE patients, NDTinE patients, and patients with RRMM.

Introduction: BCMA-directed CAR-T and Bispecific T-cell engager (BiTE) therapies have shown remarkable overall response rates in heavily pretreated patients with relapsed/refractory multiple myeloma (RRMM). This has led to the approval of idecabtagene vicleucel, ciltacabtagene autoleucel and teclistamab by the FDA, EMA and other regulatory agencies. We performed a global survey on accessibility, practice patterns, and toxicity management of commercially available CAR-T and BiTE therapies. Methods: An online survey was completed by clinicians attending the International Myeloma Society's Immune Effector Cell Therapies in Multiple Myeloma Workshop, in-person or virtually, made available for 30 days after the meeting held in March 2023, Boston, MA. Results: 87 clinicians from 16 countries completed the survey, most practicing in an academic practice (86%) and in an urban environment (89%). Sixty-four percent of the respondents practice in North America followed by Europe (25.3%) including Germany, United Kingdom, Ireland, Italy, Netherlands, Spain, France, Greece, and Cyprus, and 6.9% from Asia and 3.4% from Australia. Seventy-seven percent reported CAR-T cell therapy was approved in their country with 44.8% treating 1-5 patients and 14.9% treating &gt;5 patients per month; 67% reported BiTE therapy was approved in their country with 14.9% treating &gt;5 patients per month. Of evaluable responses (n = 40), 62% administered CAR-T therapy inpatient and 15% administered CAR-T therapy outpatient ≥ 50% of the time. Length of time between decision to treat with CAR-T therapy to infusion was 6-12 weeks for 42% of responders and &lt;6 weeks for only 20%. Most (75%) reported inpatient administration of BiTE therapy step-up dosing; 17.5% reported outpatient step-up dosing administered ≥ 50% of the time. Use of institutional or practice SOPs for CAR-T and BiTE therapy patient selection was reported by 85% and 58%, respectively, with the factors influencing SOP outlined in Table 1. Of available CAR-T therapies, 53% prefer cilta-cel and 23% reported CAR-T therapy preference depended most on patients' co-morbidities/frailty (89%), timing of next available apheresis (67%), age (56%), CNS disease (44%) and other factors. Maintenance therapy after CAR-T therapy was reportedly used by 25% and 5% of respondents in 1-10% and 11-50% of their patients, respectively, to “maintain level of response achieved” (50%) or “achieve a deeper level of response” (25%). About half (43%) of the respondents reported using an SOP or particular criteria for secondary Hemophagocytic Lympho-Histiocytosis/Macrophage Activation Syndrome/CAR-related-HLH (sHLH/MAS/CarHLH) management that varied between the use of ASTCT Working Group IEC associated HLH-like syndrome Criteria (47%) (Hines 2023), CARTOX HLH Criteria (24%) (Neelapu 2017) and HLH-2004 criteria (6%). Tocilizumab was used as cytokine release syndrome (CRS) prophylaxis only by one responder. Keppra neurologic prophylaxis was used by 47.5% and 15% of responders for CAR-T and BiTE therapy, respectively. Delayed neurotoxicity with CAR-T was reported in 1-5% of patients by 57.5% of responders and 6-10% of patients by 15% of responders; most common manifestations were other movement/neuromuscular disorder (62%), nerve palsy (55%), and Parkinsonism (45%). Infectious prophylaxis was used to protect against HSV (92.5%), PJP (90%), bacterial pathogens (55%), fungal pathogens (60%), and IVIG (77.5%). However, criteria for infectious prophylaxis use varies widely incorporating IgG levels, infectious history, CD4+ count, B-cell aplasia and cytopenias (48.1 - 88.9%). Most respondents (46.3 - 86.5%) reported completing an infectious work-up including CMV, EBV, Hep B/C, and HIV ( Table 2). Conclusions: Trends of CAR-T and BiTE therapy use and patterns of concurrent prophylactic and supportive care in MM vary widely among academic centers across the globe, demonstrating a need for further understanding of toxicity pathogenesis, toxicity management and consistent guidelines. This survey also demonstrates the great unmet need for access beyond urban centers among the international myeloma community. Prospective studies and claims data analysis should be utilized to evaluate the longitudinal cost of care, quality of life, duration of response and management of infectious disease, neurological or related complications of CAR-T and bispecific TCE therapies.

PURPOSE At the primary analysis of CASTOR (median follow-up, 7.4 months), daratumumab plus bortezomib and dexamethasone (D-Vd) significantly prolonged progression-free survival versus bortezomib and dexamethasone (Vd) alone in relapsed or refractory multiple myeloma (RRMM). We report updated efficacy and safety results at the final analysis for overall survival (OS). METHODS CASTOR was a multicenter, randomized, open-label, phase III study during which eligible patients with ≥ 1 line of prior therapy were randomly assigned to Vd (up to eight cycles) with or without daratumumab (until disease progression). After positive primary analysis and protocol amendment, patients receiving Vd were offered daratumumab monotherapy after disease progression. RESULTS At a median (range) follow-up of 72.6 months (0.0-79.8), significant OS benefit was observed with D-Vd (hazard ratio, 0.74; 95% CI, 0.59 to 0.92; P = .0075). Median OS was 49.6 months with D-Vd versus 38.5 months with Vd. Prespecified subgroup analyses demonstrated an OS advantage with D-Vd versus Vd for most subgroups, including patients age ≥ 65 years and patients with one or two prior lines of therapy, International Staging System stage III disease, high-risk cytogenetic abnormalities, and prior bortezomib treatment. The most common (≥ 10%) grade 3/4 treatment-emergent adverse events with D-Vd versus Vd were thrombocytopenia (46.1% v 32.9%), anemia (16.0% v 16.0%), neutropenia (13.6% v 4.6%), lymphopenia (10.3% v 2.5%), and pneumonia (10.7% v 10.1%). CONCLUSION D-Vd significantly prolonged OS in patients with RRMM, with the greatest OS benefit observed in patients with one prior line of therapy. To our knowledge, our results, together with the OS benefit observed with daratumumab plus lenalidomide and dexamethasone in the phase III POLLUX study, demonstrate for the first time an OS benefit with daratumumab-containing regimens in RRMM (ClinicalTrials.gov identifier: NCT02136134 [CASTOR]).

Summary: The multiple myeloma treatment landscape has changed dramatically. This change, paralleled by an increase in scientific knowledge, has resulted in significant improvement in survival. However, heterogeneity remains in clinical outcomes, with a proportion of patients not benefiting from current approaches and continuing to have a poor prognosis. A significant proportion of the variability in outcome can be predicted on the basis of clinical and biochemical parameters and tumor-acquired genetic variants, allowing for risk stratification and a more personalized approach to therapy. This article discusses the principles that can enable the rational and effective development of therapeutic approaches for high-risk multiple myeloma.

Abstract We explored minimal residual disease (MRD) in relapsed/refractory multiple myeloma (RRMM) and transplant-ineligible (TIE) newly diagnosed multiple myeloma (NDMM) using data from 4 phase 3 studies (POLLUX, CASTOR, ALCYONE, and MAIA). Each study previously demonstrated that daratumumab-based therapies improved MRD negativity rates and reduced the risk of disease progression or death by approximately half vs standards of care. We conducted a large-scale pooled analysis for associations between patients achieving complete response or better (≥CR) with MRD-negative status and progression-free survival (PFS). MRD was assessed via next-generation sequencing (10−5 sensitivity threshold). Patient-level data were pooled from all 4 studies and for patients with TIE NDMM and patients with RRMM who received ≤2 prior lines of therapy (≤2 PL). PFS was evaluated by response and MRD status. Median follow-up (months) was 54.8 for POLLUX, 50.2 for CASTOR, 40.1 for ALCYONE, and 36.4 for MAIA. Patients who achieved ≥CR and MRD negativity had improved PFS vs those who failed to reach CR or were MRD positive (TIE NDMM and RRMM hazard ratio [HR] 0.20, P &lt; .0001; TIE NDMM and RRMM ≤2 PL HR 0.20, P &lt; .0001). This benefit occurred irrespective of therapy or disease setting. A time-varying Cox proportional hazard model confirmed that ≥CR with MRD negativity was associated with improved PFS. Daratumumab-based treatment was associated with more patients reaching ≥CR and MRD negativity. These findings represent the first large-scale analysis with robust methodology to support ≥CR with MRD negativity as a prognostic factor for PFS in RRMM and TIE NDMM. These trials were registered at www.clinicaltrials.gov as #NCT02076009, #NCT02136134, #NCT02195479, and #NCT02252172.

Introduction: IBER is an oral, potent novel cereblon E3 ligase modulator (CELMoD) agent with marked synergistic tumoricidal and immune-stimulatory effects in combination with BORT or DARA in preclinical models. CC-220-MM-001 is a phase 1/2 study evaluating dose escalations of IBER with different treatment combinations in independent cohorts, in patients (pts) with RRMM (NCT02773030); the IBER + DEX cohort showed a favorable safety profile with promising efficacy and a selected IBER RP2D of 1.6 mg 21/28 days (D). Here, we present results from the IBER + DARA + DEX (IberDd) and IBER + BORT + DEX (IberVd) cohorts. Methods: Eligible pts had received ≥ 2 prior regimens in the IberDd cohort, and ≥ 1 prior regimen in the IberVd cohort, containing at least lenalidomide or pomalidomide, and a proteasome inhibitor (PI), and had experienced disease progression on or within 60 days of last MM therapy. Escalating doses of IBER were given orally, in the IberDd cohort on D1-21, with DARA (16 mg/kg) on D1, D8, D15, and D22 (cycles [C]1-2), D1 and D15 (C3-6), and D1 (C ≥ 7), of each 28-day cycle; in the IberVd cohort, on D1-14, with BORT (1.3 mg/m2) on D1, D4, D8, and D11 (C1-8), and on D1 and D8 (C ≥ 9), of each 21-day cycle. In both cohorts DEX was given weekly. Primary objectives were to evaluate MTD, RP2D, and safety separately for each cohort; a key secondary objective was preliminary assessment of efficacy. Immune profiling was evaluated by flow cytometry from pt peripheral blood at C1D1, C2D15, C4D1, and C4D15. Results: As of June 18, 2020, 19 pts had received IberDd and 21 pts IberVd. Baseline characteristics for the 2 independent cohorts are shown in the table. All pts were refractory to their last prior regimen, and exposure to prior regimens was heterogeneous. IBER doses ranged from 1.0 to 1.6 mg; the MTD/RP2D has not been reached in either cohort. Median follow-up was 5 (0-14) and 3 (0-11) months, 10 (53%) and 13 (62%) pts continue on treatment, median cycles received was 5 (1-14) and 4.5 (1-17), with IberDd and IberVd, respectively. Grade (Gr) 3-4 treatment-emergent adverse events (TEAEs) were reported in 14 (78%) pts with IberDd, and in 13 (65%) pts with IberVd. Most frequent Gr 3-4 TEAEs of interest included neutropenia (50%), leukopenia (22%), and anemia (22%) with IberDd; and neutropenia (20%) and thrombocytopenia (20%) with IberVd. In both cohorts, neutropenia was managed with G-CSF. One pt (IberDd; 1.2 mg dose) had Gr 4 neutropenic sepsis. Occurrence of Gr 3-4 non-hematological TEAEs was low in both cohorts. One pt had Gr 2 infusion-related reaction with IberDd, and 3 pts had Gr 1-2 peripheral neuropathy with IberVd. Six (33%) and 4 (20%) pts had IBER dose reductions with IberDd and IberVd, respectively. In the IberDd cohort, with 12/19 (63%) DARA-refractory pts and 11 (58%) quad-class-refractory pts, the overall response rate (ORR) was 35% across all dosing groups (2 very good partial responses [VGPRs], 4 partial responses [PRs]); the clinical benefit rate (CBR) was 47% and disease control rate (DCR) was 88%. In the IberVd cohort, with 16/21 (76%) PI-refractory pts, 9 (43%) BORT-refractory pts, and 10 (48%) quad-class refractory pts, ORR was 50% (1 complete response, 3 VGPRs, 6 PRs); CBR was 65% and DCR was 85%. Responses with IberDd and IberVd were observed irrespective of DARA- and BORT-refractoriness, respectively. Median time to response was 4.1 (4.1-12.0) and 4.9 (3.0-13.1) weeks, in the IberDd and IberVd cohorts, respectively; median duration of response was not reached in both cohorts. Immune profiling showed dose-dependent decreases in B cells and increases in activated and differentiated T cells, in both cohorts. Except for reductions in CD38+ T cells in pts receiving IberDd, these observations were similar in pts treated with IBER + DEX. Conclusions: IberDd and IberVd showed a favorable tolerability profile in heavily pretreated RRMM pts, with promising clinical activity, even among pts refractory to the last prior regimen and previously exposed to IMiD agents, PIs, and CD38 antibodies. Immune-profiling data confirm that IBER + DEX was pharmacodynamically active in triplet combination and not augmented by the addition of DARA or BORT. The study is ongoing with continued enrollment at the 1.6 mg dose level for both cohorts. Updated results, including the MTD/RP2D, will be presented at the meeting. These results support the further development of IBER-based regimens in MM; phase 3 trials are planned to further evaluate these combinations. Disclosures van de Donk: Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Ferrer: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding. Popat:Takeda: Consultancy, Honoraria, Other: Travel support, Research Funding; Bristol Myers Squibb: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); AbbVie: Consultancy, Honoraria; GSK: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company). Larsen:Janssen Oncology: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees. Minnema:Servier: Consultancy; Kite, a Gilead Company: Speakers Bureau; Celgene: Other: travel support, Research Funding; Amgen: Consultancy. Jagannath:BMS, Janssen, Karyopharm, Legend Biotech, Sanofi, Takeda: Consultancy. Oriol:Sanofi: Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Consultancy, Speakers Bureau. Zonder:Prothena: Consultancy; Intellia: Membership on an entity's Board of Directors or advisory committees, Other: Personal fees; Celgene: Research Funding; BMS: Consultancy, Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees, Other: Personal fees; Oncopeptide: Membership on an entity's Board of Directors or advisory committees, Other: Personal fees; Alnylam: Membership on an entity's Board of Directors or advisory committees, Other: Personal fees; Janssen: Consultancy, Other: Personal fees; Caelum: Consultancy; Takeda: Membership on an entity's Board of Directors or advisory committees, Other: Personal fees. Richardson:Celgene/BMS, Oncopeptides, Takeda, Karyopharm: Research Funding. Rodriguez-Otero:Sanofi: Consultancy, Honoraria; Medscape: Membership on an entity's Board of Directors or advisory committees; Celgene/Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); GlaxoSmithKline: Consultancy, Current Employment, Current equity holder in publicly-traded company, Honoraria; Abbvie: Consultancy, Honoraria; Kite: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Amgen: Consultancy, Honoraria; Oncopeptides: Consultancy, Honoraria. Badros:Amgen: Consultancy; University of Maryland: Current Employment. Stadtmauer:Sanofi: Consultancy; AbbVie: Research Funding; Takeda: Consultancy; Bristol Myers Squibb: Consultancy, Research Funding. Bringhen:Bristol-Myers Squibb: Honoraria; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Siegel:Takeda: Consultancy, Honoraria, Speakers Bureau; BMS: Consultancy, Honoraria, Speakers Bureau; Amgen: Consultancy, Honoraria, Speakers Bureau; Merck: Consultancy, Honoraria, Speakers Bureau; Janssen: Consultancy, Honoraria, Speakers Bureau; Celulatiry: Consultancy; Karyopharma: Consultancy, Honoraria. Gamberi:Janssen: Consultancy, Honoraria; GSK: Consultancy; Amgen: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria; Bristol Myers Squibb: Consultancy, Honoraria. Gironella Mesa:Janssen: Consultancy, Honoraria; Bristol Myers Squibb: Honoraria, Speakers Bureau. Sonneveld:Bristol-Myers Squibb: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Karyopharm: Consultancy, Honoraria, Research Funding; Skyline Dx: Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Sanofi: Consultancy. Nguyen:Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Di Micco:Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Sorrell:Children's Oncology Group: Other: Non-member; Previous Study Chair AAML08B1; Bristol Myers Squibb: Current Employment. Chen:Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Amatangelo:Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Kueenburg:Celgene International Sàrl, a Bristol Myers Squibb Company, Boudry, Switzerland: Current Employment. Lonial:Onyx: Honoraria; Novartis: Consultancy, Honoraria, Other: Personal fees; Genentech: Consultancy; Amgen: Consultancy, Honoraria, Other: Personal fees; Merck: Consultancy, Honoraria, Other: Personal fees; Abbvie: Consultancy; Millennium: Consultancy, Honoraria; Karyopharm: Consultancy; Sanofi: Consultancy; JUNO Therapeutics: Consultancy; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Other: Personal fees, Research Funding; Janssen: Consultancy, Honoraria, Other: Personal fees, Research Funding; BMS: Consultancy, Honoraria, Other: Personal fees, Research Funding; GSK: Consultancy, Honoraria, Other: Personal fees.

Introduction: Iberdomide (IBER; CC-220) is a potent, novel cereblon (CRBN) E3 ligase modulator (CELMoD) agent under investigation in a phase 1/2 dose-escalation study in relapsed/refractory multiple myeloma (MM) (CC-220-MM-001; NCT02773030). IBER modulates CRBN to induce ubiquitination and proteasome-dependent degradation of Ikaros/Aiolos, resulting in anti-myeloma and immunomodulatory activity. Compared with immunomodulatory drugs (IMiDs), IBER binds to CRBN with 20-fold higher affinity and is more efficient at degrading Ikaros/Aiolos. Additionally, IBER can overcome IMiD drug resistance. Here, we evaluate the preclinical activity of IBER in combination with monoclonal antibodies (mAbs) and assess immune pharmacodynamic changes of IBER + daratumumab (DARA) among patients in the CC-220-MM-001 study. Methods: Preclinical analyses were performed on MM cell lines and peripheral blood mononuclear cells (PBMCs) from healthy volunteers. In co-culture assays, cell lines and immune cells were treated with clinically relevant concentrations of lenalidomide (LEN; 1 μM), pomalidomide (POM; 300 nM), and IBER (20 nM) alone, and in combination with DARA or elotuzumab (ELO). Clinical biomarker data were obtained from blood samples of patients enrolled in IBER + dexamethasone (DEX) and IBER + DARA + DEX cohorts of the CC-220-MM-001 study. Immune profiling was evaluated by flow cytometry on Cycle (C) 1 Day (D) 1, C2D15, C4D1, and C4D15. Results: Treatment of CD3-stimulated PBMCs with IBER increased cytokine secretion more potently than with IMiD drugs, promoting natural killer (NK) cell proliferation and increasing NK cell numbers by &gt; 30% in cultures. Treatment of CD3-stimulated PBMCs with IBER also promoted immune-mediated killing of MM cell lines, and pretreatment of MM cell lines for 48 h followed by washout sensitized cells to immune-mediated clearance. IBER treatment of MM cells increased protein expression of CD38, but had no discernable effect on SLAMF7 expression. IBER in combination with DARA or ELO enhanced the immune-mediated killing of MM cell lines and resulted in deeper cell killing compared with LEN or POM when combined with the same mAbs. Analogous to preclinical data, immune profiling of patients treated with IBER + DEX demonstrated an immune-stimulatory effect, including increased proliferating NK and T cells. Notably, patients coming on trial directly after a DARA-containing regimen showed depleted NK cell counts, which rebounded by nearly 2-fold after 1 cycle of IBER + DEX. Additionally, the effects of IBER on T and NK cell proliferation were similar in patients treated with IBER + DEX + DARA and IBER + DEX, except for overall reduction in CD38-expressing NK and T cells in patients receiving DARA. Conclusions: IBER induced immune-stimulatory activity more potently than LEN or POM, enhancing cytokine release and NK cell proliferation. MM cells treated with IBER were also sensitized to immune-mediated clearance. These data suggest that IBER may enhance the activity of biologics that exert anti-malignant activity through antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity. Accordingly, IBER enhanced the activity of DARA and ELO in co-culture. IBER also induced an immune-stimulatory effect on NK and T cells in vivo, confirming immune-stimulatory effects of IBER in patients with MM. Notably, the effect of IBER on NK cells was more pronounced in patients whose last treatment regimen contained DARA, suggesting IBER treatment may contribute to NK cell recovery after DARA treatment. Furthermore, immune changes observed by the addition of DARA to IBER + DEX were similar, suggesting IBER was the primary agent promoting immunomodulation in this triplet therapy. Together, these data support continued clinical development of IBER in combination with CD38- and SLAMF7-directed mAbs as well as other immune-directed therapies for the treatment of MM. Disclosures Amatangelo: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Bjorklund:Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Ma:Bristol Myers Squibb: Current Employment. Wollerman:Bristol Myers Squibb: Current Employment. Pierceall:Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Lonial:JUNO Therapeutics: Consultancy; Merck: Consultancy, Honoraria, Other: Personal fees; Abbvie: Consultancy; GSK: Consultancy, Honoraria, Other: Personal fees; BMS: Consultancy, Honoraria, Other: Personal fees, Research Funding; Novartis: Consultancy, Honoraria, Other: Personal fees; Takeda: Consultancy, Other: Personal fees, Research Funding; Genentech: Consultancy; Karyopharm: Consultancy; Sanofi: Consultancy; Amgen: Consultancy, Honoraria, Other: Personal fees; Janssen: Consultancy, Honoraria, Other: Personal fees, Research Funding; Onyx: Honoraria; Millennium: Consultancy, Honoraria; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees. van de Donk:Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Ferrer: Membership on an entity's Board of Directors or advisory committees. Popat:Celgene: Consultancy, Honoraria; Bristol Myers Squibb: Consultancy, Honoraria; Takeda: Consultancy, Honoraria, Other: Travel support, Research Funding; AbbVie: Consultancy, Honoraria; GSK: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Janssen: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company). Jagannath:BMS, Janssen, Karyopharm, Legend Biotech, Sanofi, Takeda: Consultancy. Zonder:Intellia: Membership on an entity's Board of Directors or advisory committees, Other: Personal fees; BMS: Consultancy, Research Funding; Alnylam: Membership on an entity's Board of Directors or advisory committees, Other: Personal fees; Celgene: Research Funding; Prothena: Consultancy; Janssen: Consultancy, Other: Personal fees; Oncopeptide: Membership on an entity's Board of Directors or advisory committees, Other: Personal fees; Caelum: Consultancy; Amgen: Membership on an entity's Board of Directors or advisory committees, Other: Personal fees; Takeda: Membership on an entity's Board of Directors or advisory committees, Other: Personal fees. Minnema:Kite, a Gilead Company: Speakers Bureau; Servier: Consultancy; Amgen: Consultancy; Celgene: Other: travel support, Research Funding. Oriol:Amgen: Consultancy, Speakers Bureau; Janssen: Consultancy; Sanofi: Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Larsen:Janssen Oncology: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees. Badros:Amgen: Consultancy; University of Maryland: Current Employment. Rodriguez-Otero:Sanofi: Consultancy, Honoraria; Celgene/Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Janssen: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); GlaxoSmithKline: Consultancy, Current Employment, Current equity holder in publicly-traded company, Honoraria; Medscape: Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria; Oncopeptides: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Kite: Consultancy, Honoraria. Sonneveld:Bristol-Myers Squibb: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Karyopharm: Consultancy, Honoraria, Research Funding; Skyline Dx: Honoraria, Research Funding; Sanofi: Consultancy; Amgen: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding. Nguyen:Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Hong:Bristol Myers Squibb: Current Employment. Sorrell:Bristol Myers Squibb: Current Employment; Children's Oncology Group: Other: Non-member; Previous Study Chair AAML08B1. Thakurta:Bristol Myers Squibb: Current Employment; Oxford University: Other: Visiting professor.

Introduction: Iberdomide (IBER; CC-220) is a potent, novel cereblon (CRBN) E3 ligase modulator (CELMoD) agent under investigation in a phase 1/2 dose-escalation study for relapsed/refractory multiple myeloma (MM) (CC-220-MM-001; NCT02773030). IBER modulates CRBN to induce ubiquitination and proteasome-dependent degradation of Ikaros/Aiolos, resulting in antimyeloma and immunomodulatory activity. Compared with immunomodulatory drugs (IMiDs); IBER binds to CRBN with 20-fold higher affinity and is more efficient at degrading Ikaros/Aiolos. Additionally, IBER can overcome IMiD drug resistance. Here, we compare the preclinical activity of IBER versus IMiD drugs + proteasome inhibitors (PIs), and assess the pharmacodynamic (PD) activity of IBER in patients treated with IBER + dexamethasone (DEX), IBER + DEX + bortezomib (BORT), and IBER + DEX + carfilzomib (CFZ). Methods: MM cell lines and peripheral blood mononuclear cells (PBMCs) from healthy volunteers were analyzed. Cell lines treated with PIs (BORT and CFZ) were pulsed with drug for 1 h, and then treated with clinically relevant concentrations of lenalidomide (LEN; 1 μM), pomalidomide (POM; 300 nM), or IBER (20 nM). Biomarker data for PD analyses were obtained from blood samples of patients enrolled in the IBER + DEX, IBER + DEX + BORT, and IBER + DEX + CFZ cohorts of the CC-220-MM-001 study. Degradation of Ikaros/Aiolos in peripheral blood was analyzed on Cycle (C) 1 Day (D) 1, pre-dose, and post IBER/IBER + PI dose by flow cytometry. Immune profiling was evaluated by flow cytometry from peripheral blood at C1D1, C2D15, C4D1, and C4D15. Results : Proteasome inhibition in cell lines after 1 h pulse of PI was maintained after washout. However, substrate degradation by IBER was affected only minimally by combination with PIs, and was more potent than by LEN or POM. These results correlate with synergistic antiproliferative activity and more potent tumoricidal activity in cell lines treated with IBER + PI than IMiD + PI combinations. Furthermore, ex vivo treatment of PBMCs with IBER + PIs minimally affected cytokine induction by IBER. Analysis of patient samples from the CC-220-MM-001 study confirmed preclinical observations showing minimal inhibition of IBER PD with the addition of PIs to the treatment regimen. In patient T cells, Ikaros and Aiolos protein levels decreased by &gt; 50% and &gt; 70%, respectively, with IBER + DEX, and by &gt; 30% and &gt; 45% (at lower IBER doses) with IBER + DEX + BORT or IBER + DEX + CFX. In all cohorts, the nadir of substrate expression was determined to be 6 h. After repeated dosing (mid-C1) patients treated with IBER + PIs showed &gt; 70% decreases in both Ikaros and Aiolos expression. Furthermore, immune profiling of patients showed that the addition of PIs to the IBER treatment regimen did not inhibit immune-stimulatory activity of IBER, including induction of NK and T cell proliferation. Conclusions: Preclinically, IBER induced substrate degradation in the presence of PIs, and treatment with IBER + PIs resulted in substantially increased tumoricidal activity. Deeper substrate degradation and increased apoptosis were also observed when PIs were combined with IBER versus IMiD drugs. Clinically, IBER led to rapid decreases in substrate levels, even in the presence of PIs, and levels were reduced further with repeated dosing, suggesting that concurrent administration of PIs minimally affects proteasomal degradation of substrates mediated by IBER. Furthermore, increases in NK and T cell proliferation in IBER-treated patients were consistent whether or not they also received a PI, further confirming that IBER has immune-stimulatory activity in combination with PIs. These data support continued clinical development of IBER in combination with PIs for the treatment of MM. Disclosures Amatangelo: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Bjorklund:Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Kang:Bristol Myers Squibb: Current Employment. Mukhopadhyay:Bristol Myers Squibb: Other: Contract scientist, Research & Early Development. Jiménez Nuñez:CITRE, a Bristol-Myers Squibb Company: Current Employment. Wong:Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Pierceall:Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Lonial:Merck: Consultancy, Honoraria, Other: Personal fees; Genentech: Consultancy; Karyopharm: Consultancy; Sanofi: Consultancy; BMS: Consultancy, Honoraria, Other: Personal fees, Research Funding; Janssen: Consultancy, Honoraria, Other: Personal fees, Research Funding; Novartis: Consultancy, Honoraria, Other: Personal fees; Takeda: Consultancy, Other: Personal fees, Research Funding; Amgen: Consultancy, Honoraria, Other: Personal fees; GSK: Consultancy, Honoraria, Other: Personal fees; Abbvie: Consultancy; Millennium: Consultancy, Honoraria; JUNO Therapeutics: Consultancy; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees; Onyx: Honoraria. van de Donk:Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees. Popat:GSK: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); AbbVie: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Takeda: Consultancy, Honoraria, Other: Travel support, Research Funding; Bristol Myers Squibb: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Jagannath:BMS, Janssen, Karyopharm, Legend Biotech, Sanofi, Takeda: Consultancy. Zonder:Caelum: Consultancy; Intellia: Membership on an entity's Board of Directors or advisory committees, Other: Personal fees; Alnylam: Membership on an entity's Board of Directors or advisory committees, Other: Personal fees; Oncopeptide: Membership on an entity's Board of Directors or advisory committees, Other: Personal fees; Celgene: Research Funding; Janssen: Consultancy, Other: Personal fees; Prothena: Consultancy; Amgen: Membership on an entity's Board of Directors or advisory committees, Other: Personal fees; BMS: Consultancy, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Other: Personal fees. Minnema:Celgene: Other: travel support, Research Funding; Servier: Consultancy; Amgen: Consultancy; Kite, a Gilead Company: Speakers Bureau. Oriol:GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy; Amgen: Consultancy, Speakers Bureau; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Larsen:Janssen Oncology: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees. Badros:Amgen: Consultancy; University of Maryland: Current Employment. Rodriguez-Otero:Sanofi: Consultancy, Honoraria; GlaxoSmithKline: Consultancy, Current Employment, Current equity holder in publicly-traded company, Honoraria; Amgen: Consultancy, Honoraria; Medscape: Membership on an entity's Board of Directors or advisory committees; Celgene/Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Janssen: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Oncopeptides: Consultancy, Honoraria; Kite: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria. Sonneveld:Bristol-Myers Squibb: Consultancy, Honoraria, Research Funding; Sanofi: Consultancy; Amgen: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Skyline Dx: Honoraria, Research Funding; Karyopharm: Consultancy, Honoraria, Research Funding. Nguyen:Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Hong:Bristol Myers Squibb: Current Employment. Sorrell:Children's Oncology Group: Other: Non-member; Previous Study Chair AAML08B1; Bristol Myers Squibb: Current Employment. Thakurta:Oxford University: Other: visiting professor; Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company.