Refractory Multiple Myeloma Patients Research Articles

Efficacy of a Daltuzumab-containing Regimen in Patients with mSMART High-Risk Multiple Myeloma

To investigate the efficacy and safety of a treatment regimen based on daratumumab in patients with high-risk relapsed refractory multiple myeloma(MM) with mSMART 3.0 score. Clinical data were collected from 16 patients with mSMART3.0 score high-risk relapsed refractory MM treated at the Affiliated Hospital of Shandong University of Traditional Chinese Medicine from May 2020 to May 2023, all of whom received daltezumab-based regimen (regimen drugs including dexamethasone, isazomib, bortezomib, lenalidomide). The efficacy and safety of the treatment were retrospectively analyzed. The median age of 16 patients was 63.5 (47-70) years old, including 10 cases of IgG type, 2 cases of IgA type, and 4 cases of light chain type. The curative efficacy was judged in all 16 patients, with an overall response rate of 93.75% (15/16), including 4 cases of strict complete remission (sCR), 1 case of complete remission (CR), 2 case of very good partial remission (VGPR), partial remission (PR) in 5 cases, and minor remission (MR) in 3 cases. The median follow-up time was 11(2-30) months, and the median progression-free survival and median overall survival were not achieved in 16 patients at the median follow-up period. The hematologic adverse effects of the treatment regimen using daratumumab-based were mainly neutropenia, and the non-hematologic adverse effects were mainly infusion-related adverse reactions and infections. Daratumumab-based regimen for the treatment of relapsed refractory MM patients with high risk of mSMART3.0 score has better efficacy and safety.

Belantamab mafodotin in triple-refractory multiple myeloma patients: A retro-prospective observational study in Italy.

Belantamab mafodotin is the first-in-class antibody-drug conjugates targeting B-cell maturation antigen to have demonstrated effectiveness in triple-class refractory multiple myeloma (TCR-MM) patients. We performed a retrospective study including 78 TCR patients, with at least four prior lines of therapy (LOTs), who received belantamab mafodotin within named patient program and expanded access program in Italy between 2020 and 2022. Median age was 65 years (range 42-86 years), ECOG performance status was ≥1 in 45% of patients. Overall, a clinical benefit was obtained in 36 out of 74 evaluable patients (49%), with 43%, 28%, and 13.5% achieving at least partial response, very good partial response, and complete response, respectively. After a median follow-up of 12 months (range 6-21 months), median duration of response, progression-free survival (PFS), and overall survival (OS) were 14, 5.5, and 12 months, respectively. Age >70 years, good performance status and response were associated with longer PFS and OS. Keratopathy occurred in 58% of patients (G3 2.5%), corneal symptoms in 32% (G3 1.2%) and a reduction in visual acuity in 14%. Grade 3 thrombocytopenia occurred in 9% of patients. Only 3% of patients discontinued belantamab mafodotin because of side effects. This real-life study demonstrated significant and durable responses of belantamab in TCR-MM patients with four prior LOTs, otherwise ineligible for novel immunotherapies.

An observational study of once-weekly carfilzomib in patients with multiple myeloma in Japan (Weekly-CAR study).

Background: The ARROW study demonstrated that once-weekly carfilzomib and dexamethasone (wKd) therapy significantly prolonged progression-free survivalcompared with twice-weekly carfilzomib and dexamethasonetherapy in relapsed or refractory multiple myelomapatients. Aim: To describe the treatment patterns, effectiveness and safety of wKd therapy in real-world settings in Japan. Methods: We investigated data from the medical records of 126 Japanese patients with relapsed or refractory multiple myeloma. Results: The overall response rate was 66.3%. The median progression-free survival was 9.5months. The incidence of treatment-emergent adverse events of any grade and grade ≥3 were 45.8and 20.8%, respectively. Conclusion: There were no new or unexpected safety signals in this study. This study demonstrated the effectiveness and safety profiles of wKd therapy in Japan.

Bone marrow stromal cells dictate lanosterol biosynthesis and ferroptosis of multiple myeloma

Ferroptosis has been demonstrated a promising way to counteract chemoresistance of multiple myeloma (MM), however, roles and mechanism of bone marrow stromal cells (BMSCs) in regulating ferroptosis of MM cells remain elusive. Here, we uncovered that MM cells were more susceptible to ferroptotic induction under the interaction of BMSCs using in vitro and in vivo models. Mechanistically, BMSCs elevated the iron level in MM cells, thereby activating the steroid biosynthesis pathway, especially the production of lanosterol, a major source of reactive oxygen species (ROS) in MM cells. We discovered that direct coupling of CD40 ligand and CD40 receptor constituted the key signaling pathway governing lanosterol biosynthesis, and disruption of CD40/CD40L interaction using an anti-CD40 neutralizing antibody or conditional depletion of Cd40l in BMSCs successfully eliminated the iron level and lanosterol production of MM cells localized in the Vk*MYC Vk12653 or NSG mouse models. Our study deciphers the mechanism of BMSCs dictating ferroptosis of MM cells and highlights the therapeutic potential of non-apoptosis strategies for managing refractory or relapsed MM patients.

Abstract CT071: Clinical activity of P-BCMA-ALLO1, a B-cell maturation antigen (BCMA) targeted allogeneic chimeric antigen receptor T-cell (CAR-T) therapy, in relapsed refractory multiple myeloma (RRMM) patients (pts) following progression on prior BCMA targeting therapy

Abstract Introduction: Despite therapeutic advances, multiple myeloma remains incurable. BCMA targeting immunotherapies, such as bispecific T-cell engagers (TCE) and autologous CAR-T provide high response rates, but relapses are common. Autologous CAR-T are logistically challenging due to the need for apheresis, prolonged manufacturing and occasional manufacturing failures. Importantly, pts who have progressed after a prior BCMA targeting immunotherapy are an emerging area of high unmet need. Emerging data indicate that autologous CAR-T have lower clinical activity in pts ho have progressed on TCE. Methods: P-BCMA-ALLO1 is an allogeneic CAR-T therapy manufactured from healthy donor T-cells available “off-the-shelf” and being evaluated in a phase 1 clinical trial (P-BCMA-ALLO1-001) in RRMM pts. This primary objective is to determine the maximum tolerated dose of P-BCMA-ALLO1, and the key secondary objective is to investigate the anti-myeloma activity. The pts must have progressed on a prior proteasome inhibitor, immunomodulatory drug and anti-CD38 monoclonal antibody. The study allows enrollment of pts who have received prior BCMA targeting therapy. The study is exploring escalating P-BCMA-ALLO1 doses and several different lymphodepletion chemotherapy (LD) regimens. Here we report the safety and early efficacy results for the 5 pts who were treated with P-BCMA-ALLO1 after having progressed on BCMA targeting CAR-T, TCE or both. These pts were treated in arms P1 (LD: cyclophosphamide (cy) 500 mg/m2 + fludarabine (flu) 30 mg/m2 X 3 days) or arm P2 (LD: cy 1000 mg/m2 + flu 30 mg/m2 X 3 days) at a P-BCMA-ALLO1 dose of > 2 X 106 to <6 X 106 cells/kg. Results: The median pt age was 62 years and median prior lines of therapy was 10. Three pts were treated in arm P2 and 2 in arm P1. Two pts had received prior teclistamab, 2 had received prior CAR-T and 1 had received prior teclistamab and CAR-T. P-BCMA-ALLO1 was well tolerated with no dose limiting toxicities or graft vs. host disease. Three of the five pts developed cytokine release syndrome (all grade (G) 2) and one developed G2 immune effector cell neurotoxicity syndrome. Three of the five pts (60%) achieved clinical responses with all three achieving the best response of very good partial response. The two non-responders had previously received and failed to achieve clinical response with teclistamab. One pt who had previously received both teclistamab and CAR-T achieved VGPR. Conclusion: In conclusion, P-BCMA-ALLO1 is an allogeneic CAR-T that is available “on-demand” with activity in RRMM pts who have progressed following prior BCMA targeted CAR-T and TCE. We believe this is the first such report of an allogeneic CAR-T showing clinical activity in such a pt population with high unmet need. Enrollment is continuing and updated data will be presented at the meeting. Citation Format: Bhagirathbhai Dholaria, Leyla Shune, Andrew Kin, Katherine McArthur, Jeff D. Eskew, Christopher E. Martin, Sabrina Haag, Joanne McCaigue, Hamid Namini, Sam DePrimo, Stacey Cranert, Julia Coronella, Devon Shedlock, Rajesh Belani. Clinical activity of P-BCMA-ALLO1, a B-cell maturation antigen (BCMA) targeted allogeneic chimeric antigen receptor T-cell (CAR-T) therapy, in relapsed refractory multiple myeloma (RRMM) patients (pts) following progression on prior BCMA targeting therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT071.

PD-1 downregulation enhances CAR-T cell antitumor efficiency by preserving a cell memory phenotype and reducing exhaustion

BackgroundDespite the encouraging outcome of chimeric antigen receptor T cell (CAR-T) targeting B cell maturation antigen (BCMA) in managing relapsed or refractory multiple myeloma (RRMM) patients, the therapeutic side effects...

Sensitivity, specificity, and accuracy of molecular profiling on circulating cell-free DNA in refractory or relapsed multiple myeloma patients, results of MM-EP1 study

As a promising alternative to bone marrow aspiration (BMA), mutational profiling on blood-derived circulating cell-free tumor DNA (cfDNA) is a harmless and simple technique to monitor molecular response and treatment resistance of patients with refractory/relapsed multiple myeloma (R/R MM). We evaluated the sensitivity and specificity of cfDNA compared to BMA CD138 positive myeloma plasma cells (PCs) in a series of 45 R/R MM patients using the 29-gene targeted panel (AmpliSeq) NGS. KRAS, NRAS, FAM46C, DIS3, and TP53 were the most frequently mutated genes. The average sensitivity and specificity of cfDNA detection were 65% and 97%, respectively. The concordance per gene between the two samples was good to excellent according to Cohen’s κ coefficients interpretation. An increased number of mutations detected in cfDNA were associated with a decreased overall survival. In conclusion, we demonstrated cfDNA NGS analysis feasibility and accuracy in R/R MM patients who may benefit from early phase clinical trial.

Analysis of efficacy and safety of daratumumab-containing regimen in relapsed and refractory multiple myeloma patients

Objective: To investigate the efficacy and safety in relapsed and refractory multiple myeloma (RRMM) patients with combination regimen of daratumumab. Methods: The clinical data of 42 RRMM patients admitted to Qingdao Municipal Hospital from December 2020 to November 2023 were retrospectively analyzed, which included 26 males and 16 females, with a median age of 59 (47, 82) years old. According to the number of courses of treatment with Daratumumab, patients were divided into three groups: long course group (≥9 courses, n=21), medium course group (7-8 courses, n=12), and short course group (≤6 courses, n=9). The deadline for follow-up was November 10, 2023, and the follow-up period was 15.6 (6.0, 34.0) months. After completing at least 2 courses of treatment, patients were evaluated for efficacy, including stringent complete response (sCR), complete response (CR), very good partial response (VGPR), partial response (PR), minimal response (MR), stable disease (SD), and progressive disease (PD). Basic clinical characteristics of patients, overall response rate of treatment, and adverse reactions were statistically analyzed. Kaplan-Meier method was used to compare the differences of progression-free survival (PFS) in patients with different courses of treatment. Results: Among the 42 patients, 15 (35.7%) had extramedullary disease or plasmacytic leukemia, 7 (16.6%) had amyloidosis, and 18 (42.9%) had renal insufficiency. In Mayo stage, 25 patients (59.5%) were at high risk of myeloma cytogenetic stratification, 8 patients (19%) were standard risk, 9 patients (21.4%) had no cytogenetic data. There were 16 patients with second-line treatment (38.0%), 13 patients with third-line treatment (31%), and 13 patients with more than fourth-line treatment (31%). All patients received at least 2 courses of treatment, achieving the best degree of disease response in 4 cases of sCR (9.5%), 3 cases of CR (7.1%), 10 cases of VGPR (23.8%), 11 cases of PR (26.2%), and 6 cases of MR (14.2%). The overall response rate (ORR) was 80.9% (34/42). The overall response rate was 100% (21/21) in the long course group, 91.6% (11/12) in the medium course group and 22.2% (2/9) in the short course group. Kaplan-Meier survival analysis showed that the duration of PFS was 5.0 (95%CI: 3.1-6.9) months in the short course group,>8.0 months in the medium course group, and>38.0 months in the long course group, the difference was statistically significant (P<0.05). Grade≥3 adverse reactions were mainly neutropenia (3 cases) and thrombocytopenia (1 case). None of the patients discontinued treatment due to adverse reactions. Conclusion: Treatment of RRMM with a regimen containing Daratumumab requires a longer course of treatment to achieve maximum efficacy and the adverse reactions can be controlled.

Delivery of CD47-SIRPα checkpoint blocker by BCMA-directed UCAR-T cells enhances antitumor efficacy in multiple myeloma

In the treatment of relapsed or refractory multiple myeloma patients, BCMA-directed autologous CAR-T cells have showed excellent anti-tumor activity. However, their widespread application is limited due to the arguably cost and time-consuming. Multiple myeloma cells highly expressed CD47 molecule and interact with the SIRPα ligand on the surface of macrophages, in which evade the clearance of macrophages through the activation of “don't eat me” signal. In this study, a BCMA-directed universal CAR-T cells, BC404-UCART, secreting a CD47-SIRPα blocker was developed using CRISPR/Cas9 gene-editing system. BC404-UCART cells significantly inhibited tumor growth and prolonged the survival of mice in the xenograft model. The anti-tumor activity of BC404-UCART cells was achieved via two mechanisms, on the one hand, the UCAR-T cells directly killed tumor cells, on the other hand, the BC404-UCART cells enhanced the phagocytosis of macrophages by secreting anti-CD47 nanobody hu404-hfc fusion that blocked the “don't eat me” signal between macrophages and tumor cells, which provides a potential strategy for the development of novel “off-the-shelf” cellular immunotherapies for the treatment of multiple myeloma.

Myxoma Virus Combination Therapy Enhances Lenalidomide and Bortezomib Treatments for Multiple Myeloma.

This study aimed to explore the effectiveness and safety of Myxoma virus (MYXV) in MM cell lines and primary myeloma cells obtained from patients with multiple myeloma. Myeloma cells were isolated from MM patients and cultured. MYXV, lenalidomide, and bortezomib were used in MM cells. The cytotoxicity assay was investigated using WST-1. Apoptosis was assessed through flow cytometry with Annexin V/PI staining and caspase-9 concentrations using ELISA. To explore MYXV entry into MM cells, monoclonal antibodies were used. Moreover, to explore the mechanisms of MYXV entry into MM cells, we examined the level of GFP-labeled MYXV within the cells after blocking with monoclonal antibodies targeting BCMA, CD20, CD28, CD33, CD38, CD56, CD86, CD117, CD138, CD200, and CD307 in MM cells. The study demonstrated the effects of treating Myxoma virus with lenalidomide and bortezomib. The treatment resulted in reduced cell viability and increased caspase-9 expression. Only low-dose CD86 blockade showed a significant difference in MYXV entry into MM cells. The virus caused an increase in the rate of apoptosis in the cells, regardless of whether it was administered alone or in combination with drugs. The groups with the presence of the virus showed higher rates of early apoptosis. The Virus, Virus + Bortezomib, and Virus + Lenalidomide groups had significantly higher rates of early apoptosis (p < 0.001). However, the measurements of late apoptosis and necrosis showed variability. The addition of MYXV resulted in a statistically significant increase in early apoptosis in both newly diagnosed and refractory MM patients. Our results highlight that patient-based therapy should also be considered for the effective management of MM.

Real-world outcomes in relapsed refractory multiple myeloma patients exposed to three or more prior treatments: an analysis from the ANZ myeloma and related diseases registry.

There is no currently available standard of care for triple-class exposed, relapsed refractory myeloma (RRMM) patients in Australia. CARTITUDE-1 (CART-1) was a single-arm, phase 1b/2 study of 97 triple-class exposed RRMM patients, who received BCMA-CAR-T cell therapy with ciltacabtagene autocel. Overall response rate (ORR) was 98%. Median progression free survival (PFS) and overall survival (OS) had not been reached at a median follow-up of 28 months. We performed a retrospective analysis on a cohort of CART-1 comparable RRMM patients participating in the Australian and New Zealand Myeloma and Related Diseases Registry (MRDR), to compare outcomes in triple-class exposed MM patients treated with currently available therapies, in a real-world context. The CE-MRDR cohort (n = 28) fulfilled CARTITUDE-1 eligibility (CE) criteria: ≥3 lines of therapy (LOT) including an immunomodulatory agent, proteasome inhibitor and CD38-directed monoclonal antibody (CD38mAb) and Eastern Cooperative Oncology Group Performance Status (ECOG PS) score of 0-2 at diagnosis. The modified-CE-MRDR (n = 132) received ≥3 LOT but may not have received a CD38mAb with an ECOG PS score of 3 (0-3). Responses to the first subsequent therapy after eligibility were poor - ORR was 23% and 0% with progressive disease (PD) reported in 61% and 36%, CE-MRDR and m-CE-MRDR respectively. Responses to the second subsequent therapy after eligibility were worse, ORR 0% and 31%, CE-MRDR and m-CE-MRDR respectively, with high rates of PD, particularly in CE-MRDR. Median OS was 5.4 versus 9.5 months, CE-MRDR versus m-CE-MRDR. This retrospective analysis confirms uniformly poor outcomes for Australian RRMM patients. There remains a critical need for greater accessibility to novel treatments, such as CAR-T, outside clinical trials.

Hdp-101, an Anti-BCMA Antibody-Drug Conjugate with a Novel Payload Amanitin in Patients with Relapsed Multiple Myeloma, Initial Findings of the First in Human Study

Introduction Several antibody-drug conjugates (ADCs) are currently being evaluated in clinical trials in a variety of malignancies. The vast majority of these are based on a few toxic compounds, largely limited to microtubule- or DNA-targeting toxins which impact proliferating cells and have limited efficacy in diseases with a low proliferative fraction such as multiple myeloma. Thus, new compounds with alternative modes of action and the ability to actively induce cell death in non-proliferating tumor cells could enhance the therapeutic potential of ADCs. We are currently developing amanitin based ADCs. Amanitin specifically inhibits RNA polymerase II thereby inhibiting the cellular transcription process at very low concentrations irrespective of the proliferation status of the target cell. Subsequently tumor cells enter apoptosis and are eliminated. HDP-101 an Amanitin based antibody drug conjugate HDP-101 is a new ADC targeting BCMA carrying a synthetic version of amanitin as a payload. In vitro cytotoxic potency of HDP-101 was demonstrated on BCMA-positive myeloma cell lines, as well as on non-proliferating primary CD138+ cells isolated from patients with refractory myeloma The cytotoxic effects of HDP-101 were seen even in non-proliferating myeloma cells with low BCMA density. Toxicity was observed neither in non-BCMA expressing control cells nor in myeloma cells exposed to an amanitin-loaded non-target control antibody. In murine xenograft models of human myeloma, HDP-101 caused dose-dependent tumor regression including complete remissions after a single dose in subcutaneous and as well as in disseminated models. Safety profiling in Cynomolgus monkeys revealed a good therapeutic index after repeated dosing. Our non-clinical studies concluded that this amanitin-based ADC is a novel promising approach in the therapy of multiple myeloma to overcome drug resistance and improve patient outcome. HDP-101-01 Clinical study HDP-101-01 is a first-in-human, open label, non-randomized, multicenter, phase 1/2a trial with HDP-101 in patients with myeloma whose disease has progressed. The aim of the Phase 1 dose escalation part is to determine the Maximum Tolerated Dose and/or establish the Recommended Phase 2 Dose. The primary objective of the phase 2 dose expansion phase is to assess the preliminary anti-tumor activity of HDP-101. An adaptive Bayesian logistic regression model with overdose control principle is used to guide the dose escalation steps. An Interim Analysis is planned after each cohort is completed. The design of the study ensures a safe and adaptive dose escalation to reach a potential clinical benefit in a patient who have limited or no therapeutic options. HDP-101-01 Study progress The study started enrollment in February, 2022. As of 10th of July, 2023, eight (2 female and 6 male) patients were dosed in 3 consecutive dose cohorts. The median age of the patients was 70 years, ranging between 50 and 80. All 8 patients were heavily pre-treated and multidrug-resistant. The median previous lines of treatment were 7 (5 to 15). Table 1 HDP-101-01 Results Seven of 8 patients were evaluable for dose limiting toxicities (DLTs) in the first 3 treatment cohorts. The initial 3 cohorts were well tolerated, without any DLTs, there were no signs of liver and kidney toxicity, no infusion reaction was detected. No reports of keratopathy or visual acuity loss were observed. Free payload was not detected in any of the available pharmacokinetic samples. Based on the limited data, the PK of HDP-101 was in line with our expectation based on the preclinical observations, exposure to HDP-101 is dose proportional. Anti-drug antibody (ADA) was not detected and there's no sign of immunogenicity. Objective responses were not reported in these initial cohorts however in Cohort #3 (60μg/Kg) there was one patient ongoing after 8 cycles of treatment with SD. This patient had a slow decrease in M-protein levels. Image 1 The initial dose cohorts showed good tolerability in late stage relapsed and/or refractory multiple myeloma patients. The study continues to enroll patients to higher dose cohorts at selected sites in the US, Germany, Poland and Hungary. Currently the study is enrolling patients in Cohort #4 at the dose of 80μg/Kg. Additional updates will be provided at the 2023 ASH Annual Meeting.

E3 Ubiquitin Ligase TRIM21 Enhances Macrophage-Mediated Bortezomib Resistance By Inducing M2 Polarization in Multiple Myeloma

Background: Multiple myeloma (MM) is a malignant plasma cell hematologic tumor with an increasing incidence and has become the second most common hematologic malignancy after non-Hodgkin lymphoma. Macrophage is an abundant component of the MM bone marrow microenvironment and contributes to the enhancement of MM drug resistance. Our previous study found that the expression of the E3 ubiquitin ligase TRIM21 was reduced in MM cells, and MM cells with low expression of TRIM21 showed reduced sensitivity to Bortezomib (Bort). This study aims to investigate the role and mechanism of TRIM21 in macrophage-mediated MM Bort resistance. Objective ：Explore the effect and mechanism of TRIM21 in mediating multiple myeloma Bortezomib resistance. Methods ：1. Immunofluorescence to analyze the expression of TRIM21 on macrophages in bone marrow biopsy specimens from patients with MM; 2. QPCR, western blot (WB) and flow cytometry (FCM) to detect the level of macrophage polarization markers after constructing overexpression or knockdown of TRIM21; 3. WB and FCM to detect the sensitivity of MM cells to Bort after co-culture of MM cells and macrophage; 4. Transcriptome sequencing to identify TRIM21-mediated pathway changes in macrophage; 5. QPCR and WB to verify the effect of TRIM21 on macrophage polarization after treatment with pathway inhibitors. Results:1. Immunofluorescence analysis showed increased expression of TRIM21 in macrophage from relapsed and refractory MM (RRMM) patients compared to newly diagnosed multiple myeloma (NDMM) patients;2. QPCR, WB and FCM results showed that overexpression of TRIM21 in macrophage led to decreased polarization markers of M1 phenotype and increased the polarization markers of M2 phenotype. In contrast, knockdown of TRIM21 increased M1 polarization and decreased M2 polarization; 3. WB and FCM results demonstrated that co-culture of MM cells with TRIM21-overexpressing macrophages significantly enhanced MM cell tolerance to Bortezomib and decreased MM cell apoptosis; 4. Transcriptome sequencing revealed activation of the JAK-STAT3 pathway in macrophages after TRIM21 overexpression; 5. QPCR and WB results showed that the macrophage polarization effect induced by TRIM21 overexpression was reversed after treatment with the STAT3 inhibitor C188-9. Conclusions: Our study shows that TRIM21 is overexpressed in macrophages in patients with relapsed and refractory MM. In addition, TRIM21 induces M2 polarization by activating the JAK-STAT3 pathway, thereby enhancing the protective effect of macrophage on MM cells. These findings provide a new insight into the role of TRIM21 in MM drug resistance and lay an important theoretical foundation for targeting macrophages in MM. Key words: TRIM21, Macrophage, Bortezomib, JAK-STAT3

The Role of Macrophage Migration Inhibitory Factor (MIF) in Regulation of T-Cell Activity in Multiple Myeloma

Background: Multiple myeloma (MM) is the second most common hematological malignancy associated with the overproduction of light chain or monoclonal immunoglobulin. MM remains incurable, with high relapses and refractory disease rates after first-line treatment. Hence, novel therapeutic approaches are needed to improve immune responses to prevent relapses or drug resistance after initial therapies. Immune responses are shaped by several factors, including mutations, pro- and anti-inflammatory cytokines and chemokines, and activation of immune checkpoints in the tumor microenvironment (TME) (Gonzalez et al., 2018). Macrophage migration inhibitory factor (MIF) as a soluble pro-inflammatory cytokine has become one of the most puzzling regulators of innate and adaptive immune responses. In myeloma, MIF was found to be significantly higher in MM cells from relapsed patients than those responding to the treatment. MIF has been implicated in drug resistance and suggested as a biomarker for predicting MM patient responses to proteasome inhibitors (Wang et al., 2020). We previously reported that MIF is highly expressed in MM and regulates CD84 (SLAMF5) expression in MM TME. We showed that MIF secreted from MM cells regulates PD-L1 expression through CD84 on CD14 + monocytic cells in the TME. Inhibition of MIF significantly reduced CD84 and PD-L1 expressions on human CD14 + cells and on myeloid-derived suppressor cells of the mice bearing MM (Lewinsky and Gunes et al., 2021). However, whether MIF directly regulates T-cell activity in MM TME has yet to be explored. Methods and Results: The current study reports that MIF may play a pivotal role in T-cell exhaustion in MM. Ouranalyses in published MM transcriptomic databases show that MM patients with low MIF had significantly longer overall and post-progression survival, indicating the therapeutic potential of MIF in MM. We also noted upregulated MIF gene expression in relapsed or refractory MM (R/RMM) patients (n=2) compared to that in newly diagnosed MM patients (n=7) and healthy individuals (n=9) in our and publicly available MM single-cell RNA sequencing datasets. We detected a profound MIF expression in MM cells and myeloid cell fractions, including monocytes, macrophages, and dendritic cells from the patients' bone marrow (BM) specimens. We previously reported that human MM cell lines highly express MIF. In this study, we assessed the impact of MIF secreted by MM cells on the immune cells, specifically CD8 + T cells. Our results showed that inhibition of MIF reduced the elevated T-cell exhaustion markers, PD1 and CTLA-4, on CD8 + T cells in healthy donors (HDs) peripheral blood mononuclear cells (PBMCs) following the coculturing with MM1.S cells (n=3 *P &amp;lt; 0.05 ). We also found that MIF inhibition induced the T-cell activation marker, LAMP1, on CD8 + T cells in this coculturing setting (n=3, **P &amp;lt; 0.01). Furthermore, we noted MIF inhibition reduced PD1 expression on CD8 + T cells in HDs PBMCs (n=3, **P &amp;lt; 0.01), suggesting MIF may regulate the exhaustion profile of CD8 + T cells. MIF can conduct paracrine or autocrine signalings by binding to its receptors, including CD74 and CD44, and lead to intracellular signaling cascades. Hence, we assessed CD74 gene expression as the counterpart of MIF in R/RMM, MM, and healthy patients. We noted significantly upregulated CD74 expression in R/RMM patients compared to newly diagnosed MM patients and healthy individuals. We also noted higher CD74 expression in CD8 + T cells than in CD4 + T cells in R/RMM patients, suggesting that MIF/CD74 axis may be a potential target to enhance CD8 + T cell-mediated immunity in R/RMM. To further explore the impact of MIF inhibition on MM progression, we performed a pilot in vivo study by inoculating murine 5TGM1 cells into two groups of syngeneic C57BL/KaLwRijHsd mice. After two weeks, the mice were injected with either sterile PBS as a control or a MIF inhibitor. The results of this pilot study showed that MIF inhibition significantly decreased MM cells in BM and PB of myeloma-bearing mice and reduced T-cell exhaustion markers on CD8 + T cells compared to that in the control mice (n=3-4, *P &amp;lt; 0.05, **P &amp;lt; 0.01, ***P &amp;lt; 0.001). Conclusion: Overall, our preliminary data indicate that MIF may have a crucial role in T-cell activity by regulating T-cell exhaustion markers in MM. Further studies are needed to explore the therapeutic potential of MIF to reduce T-cell exhaustion to improve anti-tumor immunity in MM.

Initial Clinical Results and Immune Correlates of a Phase 2 Study of Daratumumab, Bortezomib, Dexamethasone Followed By a Proteasome Inhibitor in-Class Transition ( iCT) to Daratumumab, Ixazomib, Dexamethasone in Relapsed Refractory Multiple Myeloma

Background: The regimen of daratumumab, bortezomib, and dexamethasone (DVd) was approved in relapsed refractory multiple myeloma (RRMM) patients (pts) with &amp;gt;1 line of therapy based on the pivotal phase 3 CASTOR study. Notably in CASTOR, bortezomib was administered for a fixed duration of 8 cycles, and both the parenteral administration route and treatment-related peripheral neuropathy (PN) may limit continuous bortezomib exposure in clinical practice. As an alternative, we conducted a phase 2 study of DVd, followed by daratumumab, ixazomib, dexamethasone (DId) utilizing a proteasome inhibitor (PI) in-class transition ( iCT) with the hypothesis that oral ixazomib may provide a more tolerable and convenient way to deliver continuous PI- and anti-CD38-based therapy to improve efficacy (NCT03763162). Methods: This phase 2 single-center study enrolled RRMM pts with 1-3 lines of prior therapy with disease progression on or following the last line of therapy. Key exclusion criteria included prior ixazomib exposure, refractoriness to anti-CD38 therapy, and refractoriness to bortezomib or carfilzomib therapy at last exposure. Enrolled pts received DVd for 3 cycles on a 21-day (D) cycle with daratumumab on D1, D8, and D15 and subcutaneous (SC) bortezomib 1.3 mg/m 2 on D1, D4, D8, and D11. Starting cycle (C) 4, pts transitioned to DId on a 28-day cycle, with daratumumab on D1 and D15 for C3-C7 and on D1 starting C8 and oral ixazomib 4 mg on D1, D8 and D15. Daratumumab was initially administered intravenously (16 mg/kg) but later changed to SC injection (1800 mg) with a protocol amendment. Bone marrow (BM) aspirates were performed pre-treatment, post-C3, post-C6 (optional), and at progression to evaluate immune correlates of therapeutic response and resistance using 4 16-color multiparameter flow cytometry panels (2 T-cell, 1 NK/myeloid, and 1 B-cell). The primary endpoint of the study was progression free survival (PFS) with planned enrollment of 40 pts. Results: As of 15 May 2023, 36 pts have enrolled with a median of 1 prior line of therapy. Median age was 66, 67% were male, 28% were Black, 97% were lenalidomide-refractory, and 42% had high-risk cytogenetics (Cg; del 17p, t(4;14), t(14;16), and/or +1q21 gain/amplification). Overall response rate was 83%, ≥very good partial response (VGPR) rate was 53%, and ≥complete response rate was 19%. At a median follow-up of 24.8 months, median PFS was 21.1 months and median response duration was 26.2 months. Median PFS among pts with high-risk Cg, 1 line of prior therapy, and 2-3 lines of prior therapy was 21.1 months, 22.8 months, and 14.3 months, respectively. The most common treatment emergent adverse events (TEAEs) of any grade were diarrhea (69%), thrombocytopenia (69%), fatigue (67%), and lymphopenia (67%). The most common ≥grade 3 TEAEs were lymphopenia (42%), thrombocytopenia (42%), and hypertension (31%). Treatment emergent PN occurred in 61% pts (11% ≥ grade 3). The most common reason for treatment discontinuation was disease progression (42%), and 16 (44%) pts remain on study with ongoing responses. Efficacy and safety stopping rules for the study have not been met. Multiparameter flow cytometry immune correlates from BM aspirates demonstrated significantly lower Ki67 + cell frequency and significantly higher PD-1 + cell frequency within the CD8 + T-cell population at baseline in pts with no response versus those with optimal responses (≥VGPR). Among pts with short PFS (&amp;lt;12 months), CD4 +/CD8 + ratio and CD4 + non-T-reg naïve T-cells were significantly higher post-C3 and post-C6 compared to pts with longer PFS (&amp;gt;12 months). Among initial responders who later progressed on therapy, T-regulatory cells were significant increased at progression compared to pre-C4, and NK cell CD16 expression was significantly reduced at progression compared to baseline. Finally, distinct patterns of CD4 + T effector memory (EM) cell subsets were observed with significantly decreased EM1 and increased EM3 subsets at progression compared to baseline. Conclusion: Treatment with DVd followed by DId with a PI iCT from bortezomib to ixazomib is a feasible approach for continuous PI and anti-CD38 therapy, leading to durable responses in RRMM pts, among whom nearly all (97%) were lenalidomide refractory. Immune correlates revealed distinct patterns of T-cell and NK-cell phenotypes when profiled serially in responding and non-responding pts. Additional correlative analyses are ongoing.

Outcomes of Triple Class Refractory Multiple Myeloma Patients: A Single Center Retrospective Study

BACKGROUND Despite recent advances in the treatment of multiple myeloma (MM), the disease remains incurable. Recent studies suggest that patients who are triple class refractory (TCR) to a proteasome inhibitor (PI), immunomodulatory agent (IMiD), and anti-CD38 monoclonal antibody (mAb) have especially poor outcomes with a median overall survival (OS) of less than 1 year. However, studies with these results have been conducted in large academic institutions. In this study, we retrospectively analyzed outcomes among MM patients with TCR MM in a single clinic specializing in the care of patients with MM. METHODS A retrospective chart review was conducted among patients with TCR MM who were treated in a single clinic specializing in the care of patients with this B-cell malignancy. From July 2003 to July 25, 2022, we determined these patients' progression-free survival (PFS), OS, cytogenetics, lines of prior therapy (LOT), and first treatment they received after they became TCR. Kaplan-Meier analysis was utilized to assess differences in PFS, OS from diagnosis, and OS from TCR status based on high-risk cytogenetics, defined as the presence of t(4;14), t(14;16), t(14;20), 1q gain, or deletion 17p, compared to those with standard-risk cytogenetics. Kaplan-Meier analysis was also used to compare PFS according to number of lines of prior LOT, time to TCR, and drug class used for the first treatment after becoming TCR. RESULTS TCR developed in 121 patients. The median time from diagnosis to development of TCR disease was 33.4 months (mo; range, 1.5-187 mo). Patients with a time to TCR status of &amp;gt; 33.4 months had a longer PFS (median 5.2 mo) compared with patients with a time to TCR status of &amp;lt; 33.4 mo (median 2.5 mo; p=0.0171). The median LOT these patients received was 7 (range, 3-26). The median LOT prior to becoming TCR was 3 (range: 2-12). The median PFS of patients from their first treatment following the development of TCR was 4.5 months; patients with &amp;lt; or &amp;gt; 3 LOT prior to becoming TCR had the same median PFS (4.5 mo). However, PFS was shorter for high-risk (median = 2.5 mo) than standard risk (median = 4.2 mo) TCR MM patients, but this did not reach statistical significance (p = 0.0633). The median OS from diagnosis of MM was 94.8 mo (range, 5.8 - 320.6 mo). Cytogenetic data was available for 65 patients (54%). Of these, 35 (54%) harbored high-risk cytogenetics. The median OS of TCR patients with high-risk cytogenetics from diagnosis was 98.2 mo and was not different from those with standard risk disease (74.2 mo; p = 0.704). Notably, the median OS of patients from the time of development of TCR was 25.5 mo (range, 1.5 - 186.8 mo); OS was shorter (median 18.7 mo) among those TCR patients with high-risk cytogenetics compared with that of standard risk (38.5 mo), but this was not significant (p = 0.1109). The first line of therapy administered following the development of TCR for the majority of patients (n= 108 [89%]) was retreatment with an IMID, PI, mAb, or a combination of agents from these drug classes. Thirteen patients (11%) were treated with a venetoclax- or alkylating agent-based combination therapy. In addition, all except 2 patients received steroids as part of their first treatment after developing TCR. The regimen with the longest PFS was the combination of a mAB and steroids (median 9.0 mo) but only 6 patients were treated with this combination. The shortest PFS was among those retreated with a PI and steroids (n = 15; median 2.4 mo). The use of an IMID with steroids was the most frequently used combination treatment (n=32) with a median PFS of 3.4 mo. CONCLUSION Despite being refractory to a PI, IMID, and mAb, TCR patients in our single-center retrospective study showed a median OS of more than 2 years (25.5 mo) from the development of TCR. This OS is the longest reported to date in this population of MM patients. Cytogenetic differences failed to predict both OS and PFS from the development of TCR. In addition, the number of prior lines of therapy did not predict PFS from their first treatment after showing TCR. The time to development of TCR, however, did predict OS as patients who took longer to become TCR had a longer median OS. The results of this study show that time to becoming TCR is a prognostic factor for this group of patients. Our study shows that OS is considerably longer for patients with TCR than has been previously reported.

Characterization of JNJ-79635322, a Novel BCMAxGPRC5DxCD3 T-Cell Redirecting Trispecific Antibody, for the Treatment of Multiple Myeloma

Background: Multiple myeloma (MM) is a genetically complex and heterogenous malignancy with a poor survival rate and accounts for approximately 10% to 15% of all hematologic cancers. Despite advances in myeloma therapy, MM remains incurable. Deep and durable clinical responses have been observed when targeting the tumor associated antigens BCMA and GPRC5D with immunotherapies. Additionally, data presented at ASCO this year demonstrated a further improvement in ORR when BCMA and GPRC5D bispecifics were given in combination to relapsed or refractory MM patients. These data suggest that broader antigen coverage by redirecting T cells to two tumor surface antigens is an effective means to harness the immune system to deplete cancer cells. Targeting two tumor antigens may also reduce the likelihood of antigen escape as a primary reason for relapse. Here, we describe JNJ-79635322, a trispecific antibody targeting B-cell maturation antigen (BCMA) and G-Protein-coupled receptor class 5 member D (GPRC5D), which are both highly expressed on plasmablasts and plasma cells in myeloma patient samples. Dual antigen recognition on plasma cells with a trispecific T-cell engaging antibody engineered with a CD3 arm has the potential to enhance tumor binding through avidity that could result in efficient depletion of malignant clonal populations and prevent tumor antigen loss mediated resistance. Methods: JNJ-79635322 is a trispecific antibody composed of an anti-CD3 binding domain an anti-BCMA binding domain, and an anti-GPRC5D binding domain. It was selected based on biophysical assessment and showed activity in multiple myeloma models. Results: JNJ-79635322 induced potent cytotoxicity in various myeloma cell lines in vitro with concomitant T-cell activation. Importantly, JNJ-79635322 was able to deplete both dual (BCMA and GPRC5D) and single (BCMA or GPRC5D) target expressing cells efficiently. In addition, dose dependent depletion of H929 myeloma cells was observed in a more physiological healthy fresh whole blood co-culture assay. In vivo, JNJ-79635322 exhibited potent antitumor activity compared to vehicle and antibody controls in a murine MM xenograft prevention model (single target expressing clonal H929 cells) and two tumor regression models (RPMI 8226 and MM.1S cells). Conclusion: JNJ-79635322 is a potential first-in-class trispecific antibody targeting BCMA and GPRC5D with the ability to deplete dual and single target expressing MM clones in preclinical studies vitro and in vivo. A Phase 1 dose-escalating study of JNJ-79635322 in myeloma patients is ongoing (NCT05652335).

Fludarabine Lymphodepletion Exposure Is Associated with Idecabtagene Vicleucel Toxicity in Relapsed and Refractory Multiple Myeloma Patients: Real-World Experience from the US Myeloma Immunotherapy Consortium

Background. Idecabtagene vicleucel (ide-cel) is an anti-B-cell maturation antigen (BCMA) CAR-T associated with durable responses in relapsed/refractory multiple myeloma (RRMM) patients. Fludarabine (Flu), part of standard lymphodepleting chemotherapy (LDC), improves T-cell expansion and persistence, but BSA dosing results in significant pharmacokinetic (PK) variability. Flu exposure, defined by the area under the curve (AUC), has been shown to predict rates of relapse after anti-CD19 CAR-T in B-cell acute lymphoblastic leukemia (Fabrizio et al, Blood Advances 2022). We hypothesized Flu AUC may predict outcomes after ide-cel and, using a published population model (Langenhorst et al, Clin Pharmacokinet 2019 ) we assessed the impact of Flu AUC on standard-of-care (SOC) ide-cel outcomes. Methods. RRMM patients receiving SOC ide-cel from 11 of the US Myeloma Immunotherapy Consortium centers were retrospectively analyzed. FluCy was given on days -5 to -3 before CAR-T infusion. Patients were excluded if they did not receive FluCy LDC or ide-cel infusion, had ESRD on hemodialysis, or did not have creatinine values on LDC days. A population PK approach using cumulative Flu dose and PK covariates, eGFR and body weight (BW), was used to calculate C max and AUC 0-72h. PK parameters were first tested as continuous variables in univariable and multivariable (MV) analysis. ORs are expressed per 1 mg * hr/L in the model. Results. 285 patients were included with a median follow-up of 8.7 (4.3-14.2) months. eGFR distribution indicated large variability (mean=86.5 ml/min, CV 38.4%), with 151 (53%) having renal dysfunction (eGFR &amp;lt;90 ml/min/1.73). BW ranged from 42 to 147.2 kg. Wide PK variability was observed with a median Flu AUC of 19.01 (11.23-41.47) mg * h/L (Fig 1). When adjusted for high-risk features including high risk cytogenetics, extramedullary disease, exposure to BCMA agents, and receipt of bridging therapy in a MV model, Flu AUC was not found to be associated with efficacy, including overall response and progression free survival. However, when adjusted for bridging therapy response and prior lines of therapy as an indicator of disease status/burden pre-CAR-T, each 1 mg * h/L increment in Flu AUC was found to be associated with maximum grade &amp;gt;/= 2 cytokine release syndrome (CRS) (OR 1.083; 95% CI 1.013-1.160; p=0.020). While there was no difference in the occurrence of Grade 3/4 cytopenias, each 1 mg * h/L increment in Flu AUC was significantly associated with use of stem cell boost (OR 1.130; 95% CI 1.038-1.235; p=0.005). Discussion. In this real-world dataset of ide-cel treated RRMM patients, Flu exposure was found to have a significant association with severe CRS and need for stem cell boost. This is consistent with prior studies (Hirayama et al, Blood, 2019) where a greater increase in cytokine levels and risk for CRS is seen with high intensity LDC. These data highlight how standard BSA-based Flu dosing results in significant PK variability and overestimates Flu AUC, increasing the risk of CAR-T toxicities. Prospective validation of our model-based findings through measurement of Flu blood levels, CAR-T PK, and clinical outcomes is warranted.

The Spop/BRD4/c-Myc Axis Modulates IMiDs Sensitivity in Multiple Myeloma

The development of novel agents including immunomodulatory drugs (IMiDs) lenalidomide (Len) and pomalidomide (Pom) has led to improved patient outcomes in multiple myeloma (MM); however, MM patients inevitably experience relapse and drug resistance. The expression level of CRBN, CRBN-binding proteins, and CRL4 CRBN ubiquitin ligase is considered to be associated with IMiDs resistance. Clinical studies have shown that MM patients can exhibit IMiDs resistance even without CRBN abnormalities, suggesting the molecular mechanisms of intrinsic resistance to IMiDs are not fully understood. To delineate the molecular mechanisms underlying IMiDs resistance, we performed genome-wide knockout (KO) screening in IMiDs-sensitive MM cells. For in vitro work, we used the MM cell lines MM1S, and H929. We used sgRNA to KO SPOP and BRD4 in MM cells. After performing a CRISPR KO screen in MM cells, we discovered that in addition to CRBN and its associated genes, sgRNAs targeting SPOP (speckle-type POZ protein, a speckled zinc finger protein) were highly enriched after treatment with Poma. Importantly, SPOP KO MM cell lines acquired significant resistance to Pom and Len treatment. To examine whether SPOP KO-induced IMiDs resistance was CRBN-pathway dependent, we assessed CRBN and its downstream interacting protein levels. SPOP KO showed no effect on CRBN expression; moreover, IMiDs can still trigger IKZF1 and IKZF3 degradation, associated with the downregulation of IRF4, suggesting that SPOP mediates sensitivity to IMiDs in a mechanism independent of CRBN-IKZF1/3 axis.Compared to plasma cells from normal donors, we found that the expression levels of SPOP were significantly decreased in MGUS patients, smoldering myeloma patients, newly diagnosed MM patients, and refractory relapsed MM patients (p-values: 2.4e-2, 2.0e-4, 9.9e-3, 3.17e-6, respectively). SPOP is the adaptor protein of the Cullin3-RING ubiquitin ligase complex. Therefore, the function of SPOP is determined by the characteristics of the substrates it recruits. We performed immunoprecipitation with overexpressed SPOP in MM cells, followed by mass spectrometry analysis, and identified BRD4 as a candidate protein binding to SPOP in MM, which was confirmed by Co-IP. KO of SPOP led to an upregulation of BRD4 protein levels in MM cells. As a downstream regulator of BRD4, the oncogene c-Myc showed a significant increase in protein expression in IMiDs-resistant MM patients. Furthermore, the KO of SPOP notably enhanced c-Myc expression in MM cells, while the KO of BRD4 in SPOP KO MM cells decreaed c-Myc expression and restored MM cell sensitivity to IMiD treatment. These findings suggest that SPOP modulates c-Myc expression through BRD4 in a CRBN-IKZF1/3 independent manner, thereby mediating MM cell sensitivity to IMiDs. BRD4 plays a significant role in the development and progression of various tumors. The BRD4 inhibitor JQ1 has been shown to exhibit anti-tumor effects in multiple types of cancer. We found that combination treatment with JQ-1 and IMiDs reversed IMiDs resistance of SPOP KO MM cell lines and primary MM cells from relapsed patients. Our data show that SPOP is a CRBN-independent modulator of IMiDs sensitivity by regulating the BRD4/c-Myc axis and provides the preclinical rationale for combining IMiDs with BRD4 inhibitors to overcome IMiDs resistance and improve patient outcomes.

Updated Results from a Matching-Adjusted Indirect Comparison of Efficacy Outcomes of Isatuximab Plus Carfilzomib and Dexamethasone Versus Daratumumab Plus Lenalidomide and Dexamethasone in Patients with Relapsed and/or Refractory Multiple Myeloma

Introduction: Findings from a previously conducted matching-adjusted indirect comparison (MAIC) between isatuximab plus carfilzomib with dexamethasone (IsaKd) and daratumumab plus lenalidomide and dexamethasone (DRd) among relapsed and/or refractory multiple myeloma (RRMM) patients receiving one to three prior lines of therapy (LoT) demonstrated a significantly better progression-free survival (PFS) and a positive trend for overall survival (OS) in favor of IsaKd compared with DRd (median follow up of 20.7 months for IKEMA trial). Additionally, IsaKd demonstrated an acceptable safety profile with significantly lower rates of several treatment-emergent adverse events than DRd [Richter J et al, Cancer Med 2023;12(7):8005-8017; Richter J et al.(Publication Number 1962), 63 rd ASH Annual Meeting and Exposition, 2021; Richter J, et al. P-213, Clin Lymphoma Myeloma Leuk. 2021;21(Suppl 2):S156-S157]. The present study used longer follow-up data from the phase 3 IKEMA trial (NCT03275285) to update the previous MAIC evaluating the comparative efficacy of IsaKd versus DRd. Methods: A MAIC was performed with the latest available individual patient-level data (IPD) from the IKEMA trial (IsaKd arm, n = 179) (data cutoff: February 2023 for OS and January 2022 for PFS), and aggregate data from study publications of phase 3 POLLUX trial (DRd arm, n = 286, NCT02076009) [Bahlis NJ et al. Leukemia 2020;34(7):1875-1884; Dimopoulos MA et al. Hemasphere 2022;6:13]. Patients were selected from the IsaKd arm of the IKEMA trial to match the inclusion and exclusion criteria of the POLLUX trial. Individual patients from the IKEMA trial were then assigned weights such that (1) weighted mean baseline characteristics for patients in the IsaKd arm matched those reported for patients in the DRd arm, and (2) each patient's weight was equal to their estimated odds (propensity) of being in the POLLUX trial versus the IKEMA trial. After matching, outcomes were compared across the two trial populations. For PFS and OS, hazard ratio (HR) and 95% confidence interval (CI) were reported from a Cox proportional hazards (PH) model using the weighted sample for IsaKd and the pseudo-IPD for DRd extracted from published Kaplan-Meier curves via digitization software [Mark M et al, Engauge Digitizer Software; http://markummitchell.github.io/engauge-digitizer]. For any violations of the PH assumption, the restricted mean survival time (RMST) at median follow-up of IKEMA for the outcome of interest was calculated instead. Results: After the MAIC adjustment, all available baseline characteristics were well balanced across the trial populations. For PFS, as the PH assumption was violated ( χ2 = 5.52, p = 0.019), RMST method was used to compare the two treatments. PFS was significantly better with IsaKd versus DRd (mean difference [95% CI]: 3.63 months [0.14-7.12]; p = 0.04) at 44 months follow-up using RMST method. For OS, the PH assumption ( χ2 = 0.89, p =0.35) was not violated. A numeric, statistically non-significant trend in favor of IsaKd versus DRd was observed for OS (Figure 1). Conclusions: This MAIC analysis demonstrated a significant benefit in PFS and a positive trend in the improvement of OS with IsaKd compared with that with DRd. These findings with a longer follow-up were consistent with the previous analyses conducted with a follow-up of 2 years. These data highlight the therapeutic potential of IsaKd, a lenalidomide-free regimen, in RRMM patients receiving one to three prior LoT compared with a lenalidomide-based regimen.