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Background: Daratumumab-based combination with proteasome inhibitors (PI) and immunomodulatory drugs (IMiDs) have revolutionized the treatment outcomes of relapsed/refractory multiple myeloma (RRMM). Several daratumumab-based triplet combinations have been approved for the management of RRMM, but outcomes of daratumumab-based triplets in patients with high-risk cytogenetics RRMM (HC-RRMM) are not well described in the literature. This study aimed to evaluate the clinical outcome of daratumumab-based regimens in patients with HC-RRMM who are daratumumab-naïve. Methods: A retrospective review of 110 patients with HC-RRMM who received daratumumab-containing regimens from 6/2016 through 2/2023 at the University of Kansas Medical Center, in collaboration with the U.S Myeloma Innovations Research Collaborative (USMIRC) was conducted. Daratumumab was combined with bortezomib/dexamethasone (DVd), carfilzomib/dexamethasone (DKd), and pomalidomide/dexamethasone (DPd) for treatment of RRMM. HC-RRMM was defined as patients with one or more cytogenetic abnormalities (on FISH panel) including -17/del(17p), t(4;14), t(14;16), t(14;20), or amplification of 1q. Responses to therapy including overall response rate (ORR), complete response or better (≥CR), and very good partial response (VGPR) were evaluated using the International Myeloma Working Group (IMWG) criteria. Descriptive statistics were used to summarize patient and disease characteristics, along with efficacy outcomes. Progression-free survival (PFS) and overall survival (OS) were calculated by Kaplan-Meier methods. Results: Of the 110 patients with HC-RRMM, the median age was 66 years (range 43-84), 83 (75%) were Caucasian, 60 (54%) had IgG isotype, 41 (37%) had revised international staging system (R-ISS) stage III disease, 35 (32%) had extramedullary disease (EMD), 57 (52%) patients had one high-risk cytogenetic (HC) abnormality, 49 (44%) had 2 HC abnormalities, while four (4%) had 3 HC abnormalities. The median number of previous lines of therapy was 2 (1-4). Eighty-eight patients (80%) were lenalidomide refractory, while 53 patients (48%) had double refractory disease to both a PI and IMiD treatment. A total of 19 (17%), 27 (25%), and 64 (58%) patients received DVd, DKd, and DPd, respectively. The overall response rate (ORR) for the entire patient population was 73%, 45% had VGPR or better, and 35% achieved ≥CR. Median follow-up was 28 months (12.07-53.57), the median OS was 28 months (95% CI 23.2 - 43.9) and PFS was 8.03 months (95% CI 5.8 - 12.2) for all treatment groups. The median PFS for 1 HC vs ³ 2 HC was 14.8 vs 4.57 months (HR 1.72, 95%CI 1.17-2.72 p = 0.006), respectively. Similarly, median OS for 1 HC vs ³ 2 HC was 43.93 vs 22.47 months (HR 1.87, 95%CI 1.15-3.05, p = 0.011), respectively. (Figure 1). On multivariate analysis, R-ISS stage III, -17/del(17p), and the presence of more than one HC abnormality were associated with poor OS. The most common cause for treatment discontinuation was progressive disease, accounting for 73% of patients in the whole cohort. As for each daratumumab-based triplet, discontinuation due progression occurred in 78%, 48%, and 83% in DVd, DKd, and DPd, respectively. Other causes of discontinuation included > grade 3 neuropathy, which occurred in 16% of patients receiving DVd, and cardiac events, which occurred in 11% of patients receiving DKd. Treatment-related mortality occurred in 2% of patients in the whole cohort. At the time of evaluation, 14 patients remain on treatment. Conclusion: Advanced stage R-ISS disease at diagnosis, presence of -17/del(17p), and 2 or more HC abnormalities were associated with poor prognosis reflected by worse PFS and OS in HC-RRMM treated with daratumumab-based therapies. A larger cohort or a prospective study in patients with HC-RRMM is needed to compare long-term outcomes between daratumumab-based therapies (DKd, DVd, and DPd).

Abstract Idecabtagene vicleucel (ide-cel) was the first chimeric antigen receptor T-cell therapy to gain US Food and Drug Administration approval for patients with relapsed/refractory multiple myeloma (RRMM). The clinical outcomes of standard of care (SOC) ide-cel in racially and ethnically diverse populations have been understudied. This study pooled data from 207 patients with RRMM (28% patients of racial and ethnic minority groups) treated with SOC ide-cel across 11 institutions to examine racial and ethnic differences in the incidence of toxicities and adverse events, response to ide-cel, and survival. This study included 22 (11%) Hispanic, 36 (17%) non-Hispanic Black, and 149 (72%) non-Hispanic White patients with RRMM. Compared with Hispanic and non-Hispanic White patients, non-Hispanic Black patients had higher median levels of C-reactive protein (1.0, 0.8, and 3.5 mg/dL, respectively; P = .02) and baseline ferritin (362.0 vs 307.0 vs 680.5, respectively; P = .08) and were more likely to develop cytokine release syndrome (77%, 85%, and 97%, respectively; P = .04). Although best overall response rate was lower among Hispanic patients (59%) than among non-Hispanic Black (86%) and White patients (86%; P = .01), there were no racial and ethnic differences in progression-free or overall survival. We provide, to our knowledge, the first and largest investigation of clinical outcomes of SOC ide-cel by race and ethnicity. Despite differences in safety and response to ide-cel, our findings encourage the use of ide-cel in all patients with RRMM. These findings should be confirmed in larger samples of diverse patients with RRMM, with longer follow-up time.

8013 Background: Ide-cel is an FDA-approved treatment for RRMM patients (pts). However, there is limited data on how BT for disease control during its manufacturing process affects clinical outcomes. Methods: Eleven US academic centers contributed data to this analysis without involvement from the manufacturer. By 5/1/2022, 235 pts had undergone leukapheresis, with 214 infused with a median follow up of 9 months (mos). BT was given between leukapheresis and CAR-T infusion. Results: In this analysis, 79% of pts (n = 170) received BT, which included alkylator-based in 35.5%, steroid and/or IMiD/Ab combos (IMiD combos) in 14%, PI combinations (PI combos) in 12%, and selinexor in 10%. BT recipients had higher ECOG PS 2-4, R-ISS 2-3, ferritin, and CRP before lymphodepleting (LD) chemo, however, no difference among BT subgroups. No difference in prior lines of therapy or penta-refractory between BT and No BT (NBT) groups or BT subgroups. Median cycle of the BT was 1 (1-7), with overall response rate (ORR) of 12%, with no difference among BT subgroups. Incidence and severity of CRS and ICANs were comparable in BT and NBT. However, pts who received BT had a longer median hospital stay compared to NBT, particularly in the alkylator/selinexor subgroups. There were no significant difference in cytopenias at day 90 post CAR-T between the BT and NBT or BT subgroups. For the 73% (n = 157) evaluable for day 90 response, there was no difference in the complete or ORR between the BT and NBT groups (41% vs. 52%; p = .2 and 84% vs. 87.5%, p = .8, respectively). Median PFS was worse at 8.1 mos in BT vs 11.5 mos in NBT (p = .03). Among BT subgroups, PFS was the longest with IMiD combos with median PFS not reached (NR), comparable to NBT, and was significantly longer than all other BT subgroups (p = 0.01). The median OS was 13.8 mos with BT and NR in NBT (p = .002). In BT subgroup analysis, alkylators had a shorter OS, although, this was not significant (p = .06). There was no significant difference in PFS and OS in relationship to response to BT (p = .6 and p = .9, respectively). Conclusions: Pts without BT had longer PFS and OS post ide-cel, likely reflective of less aggressive disease. Those who received BT with steroid/IMiD and Ab combos had similar PFS as NBT. However, BT choice is complicated by disease severity and should be evaluated per patient circumstances. [Table: see text]

Despite advances in treatment, outcomes remain poor for patients with penta-relapsed refractory multiple myeloma (RRMM). In this retrospective analysis, we evaluated the survival outcomes of penta-RRMM patients treated with (BCMA)- directed therapy (BDT). We identified 78 patients with penta-RRMM. Median age was 65 years, 29 (37%) had R-ISS stage III disease, 63 (81%) had high-risk cytogenetics, and 45 (58%) had extra-medullary disease. Median LOT prior to penta-refractory state was 5 (3–12). Amongst penta-RRMM, 43 (55%) were treated with BDT, 35 (45%) were not treated with BDT. Type of BDT received included belantamab mafadotin 15 (35%), Chimeric Antigen Receptor T-cell therapy 9 (21%), BCMA monoclonal antibody 6 (14%), and Bispecific T-cell engager 2 (5%). Eleven (25%) patients received more than one BDT. No significant differences were identified between baseline characteristics for the two groups. Patients treated with a BDT had better median overall survival, 17 vs. 6 months, HR 0.3 p-value < 0.001. Poor performance status, white race, and high-risk cytogenetics were associated with worse outcomes, whereas using a BDT was associated with better outcomes. Patients with penta-refractory MM have poor outcomes. Our retrospective analysis showed a significant survival benefit using BDT when compared to non-BDT for patients with penta-RRMM.

Abstract The overall survival (OS) has improved significantly in multiple myeloma (MM) over the last decade with the use of proteasome inhibitor and immunomodulatory drug-based combinations, followed by high-dose melphalan and autologous hematopoietic stem cell transplantation (auto-HSCT) and subsequent maintenance therapies in eligible newly diagnosed patients. However, clinical trials using auto-HSCT followed by lenalidomide maintenance have shown an increased risk of second primary malignancies (SPM), including second hematological malignancies (SHM). We evaluated the impact of SPM and SHM on progression-free survival (PFS) and OS in patients with MM after auto-HSCT using CIBMTR registry data. Adult patients with MM who underwent first auto-HSCT in the United States with melphalan conditioning regimen from 2011 to 2018 and received maintenance therapy were included (n = 3948). At a median follow-up of 37 months, 175 (4%) patients developed SPM, including 112 (64%) solid, 36 (20%) myeloid, 24 (14%) SHM, not otherwise specified, and 3 (2%) lymphoid malignancies. Multivariate analysis demonstrated that SPM and SHM were associated with an inferior PFS (hazard ratio [HR] 2.62, P &lt; .001 and HR 5.01, P &lt; .001, respectively) and OS (HR 3.85, P &lt; .001 and HR 8.13, P &lt; .001, respectively). In patients who developed SPM and SHM, MM remained the most frequent primary cause of death (42% vs 30% and 53% vs 18%, respectively). We conclude the development of SPM and SHM leads to a poor survival in patients with MM and is an important survivorship challenge. Given the median survival for MM continues to improve, continued vigilance is needed to assess the risks of SPM and SHM with maintenance therapy post–auto-HSCT.