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AbstractBackgroundPatient‐reported outcomes (PROs) are a better tool for evaluating the experiences of patients who have symptomatic, treatment‐associated adverse events (AEs) compared with clinician‐rated AEs. The authors present PROs assessing health‐related quality of life (HRQoL) and treatment‐related neurotoxicity for adjuvant capecitabine versus platinum on the Eastern Cooperative Oncology Group‐American College of Radiology Imaging Network (ECOG‐ACRIN) EA1131 trial (ClinicalTrials.gov identifier NCT02445391).MethodsParticipants completed the National Comprehensive Cancer Network Functional Assessment of Cancer Therapy–Breast Cancer Symptom Index (NFBSI‐16) and the Functional Assessment of Cancer Therapy–Gynecologic Oncology Group neurotoxicity subscale (platinum arm only) at baseline, cycle 3 day 1 (C3D1), 6 months, and 15 months. Because of early termination, power was insufficient to test the hypothesis that HRQoL, as assessed by the NFBSI‐16 treatment side‐effect (TSE) subscale, would be better at 6 and 15 months in the capecitabine arm; all analyses were exploratory. Means were compared by using t‐tests or the Wilcoxon rank‐sum test, and proportions were compared by using the χ2 test.ResultsTwo hundred ninety‐six of 330 eligible patients provided PROs. The mean NFBSI‐16 TSE subscale score was lower for the platinum arm at baseline (p = .02; absolute difference, 0.6 points) and for the capecitabine arm at C3D1 (p = .04; absolute difference, 0.5 points), but it did not differ at other times. The mean change in TSE subscale scores differed between the arms from baseline to C3D1 (platinum arm, 0.15; capecitabine arm, −0.72; p = .03), but not from baseline to later time points. The mean decline in Functional Assessment of Cancer Therapy–Gynecologic Oncology Group neurotoxicity subscale scores exceeded the minimal meaningful change (1.38 points) from baseline to each subsequent time point (all p < .05).ConclusionsDespite the similar frequency of clinician‐rated AEs, PROs identified greater on‐treatment symptom burden with capecitabine and complemented clinician‐rated AEs by characterizing patients’ experiences during chemotherapy.

AbstractThe presence of a serum immunoglobulin D (IgD) monoclonal protein (M‐protein) is seen in < 1% of patients with monoclonal gammopathies and is usually indicative of a malignant plasma cell disorder. Only a few cases of well‐documented benign monoclonal gammopathy of undetermined significance (MGUS) of IgD subtype have been reported, and only 2 of those had over 5 years of follow‐up at the time they were reported. Herein we describe longer‐term follow‐up of one of those 2 patients who has subsequently passed away from unrelated causes but never developed multiple myeloma or amyloidosis after 26 years of follow‐up. Although IgD MGUS is extremely rare, this case confirms that presence of an IgD M‐Protein is not always synonymous with a malignant plasma cell process.

AbstractArthrofibrosis, which causes joint motion restrictions, is a common complication following total knee arthroplasty (TKA). Key features associated with arthrofibrosis include myofibroblast activation, knee stiffness, and excessive scar tissue formation. We previously demonstrated that adiponectin levels are suppressed within the knee tissues of patients affected by arthrofibrosis and showed that AdipoRon, an adiponectin receptor agonist, exhibited anti‐fibrotic properties in human mesenchymal stem cells. In this study, the therapeutic potential of AdipoRon was evaluated on TGFβ1‐mediated myofibroblast differentiation of primary human knee fibroblasts and in a mouse model of knee stiffness. Picrosirius red staining revealed that AdipoRon reduced TGFβ1‐induced collagen deposition in primary knee fibroblasts derived from patients undergoing primary TKA and revision TKA for arthrofibrosis. AdipoRon also reduced mRNA and protein levels of ACTA2, a key myofibroblast marker. RNA‐seq analysis corroborated the anti‐myofibrogenic effects of AdipoRon. In our knee stiffness mouse model, 6 weeks of knee immobilization, to induce a knee contracture, in conjunction with daily vehicle (DMSO) or AdipoRon (1, 5, and 25 mg/kg) via intraperitoneal injections were well tolerated based on animal behavior and weight measurements. Biomechanical testing demonstrated that passive extension angles (PEAs) of experimental knees were similar between vehicle and AdipoRon treatment groups in mice evaluated immediately following immobilization. Interestingly, relative to vehicle‐treated mice, 5 mg/kg AdipoRon therapy improved the PEA of the experimental knees in mice that underwent 4 weeks of knee remobilization following the immobilization and therapy. Together, these studies revealed that AdipoRon may be an effective therapeutic modality for arthrofibrosis.

The treatment of relapsed/refractory multiple myeloma (MM) has evolved to include several new options. These include new combinations with second generation proteasome inhibitors (PI); second generation immunomodulators, monoclonal antibodies, CAR T cells, bispecific antibodies, selinexor, venetoclax, and many others. Most patients with MM undergo several cycles of remissions and relapse, and therefore need multiple lines of combination therapies. Selecting treatment options for relapsed/refractory MM requires consideration of resistance status to specific classes, and patient-specific factors such as age and other comorbidities should be considered. The NCCN Guidelines for MM provide a framework on which to base decisions regarding workup, treatment, and follow-up of newly diagnosed and previously treated MM. This manuscript outlines the recommendations from NCCN Guidelines for MM specific to relapsed/refractory disease.

Abstract In a retrospective analysis at 11 US medical centers, bridging therapy (BT) impact after receiving idecabtagene vicleucel was assessed in 214 patients. 79% received BT, including 12% Selinexor-containing, 45% alkylator-based, 15% proteasome inhibitor combinations, and 18% immunomodulatory drugs +/- monoclonal antibody combinations (IMiD +/- mAb combos). BT recipients had worse performance status, higher stage disease, ferritin and CRP pre-infusion. The overall response rate to BT was 12%, with no difference among BT subgroups. Safety profiles were similar, but Selinexor had a higher grade ≥2 ICANS incidence. Median progression-free survival (PFS) was 6.7 months in BT vs. 11.5 months in no-BT (p=0.007). Median PFS was longest with IMiD +/- mAb combos (12 months), comparable to no-BT, and significantly longer than other BT subgroups (p=0.01). Alkylator-based BT had inferior PFS compared to IMiD +/- mAb combos (p=0.03). Median overall survival (OS) for the BT was 13.8 months vs. not reached in no-BT (p=0.002). Alkylator-based BT had shorter OS compared to others (11.97 months vs. NR; p=0.001). Stepwise Cox regression showed alkylator-based BT and response

Introduction In the KarMMa-3 trial (NCT03651128), ide-cel, a BCMA-directed CAR T cell therapy (Tx), significantly improved median progression-free survival (13.3 vs 4.4 mo, HR 0.49, P &lt; 0.001) and overall response rate (71% vs 42%, P &lt; 0.001) vs std regimens in pts with RRMM who were TCE to immunomodulatory (IMiD ®) agents, proteasome inhibitors (PIs), and daratumumab (Rodríguez-Otero NEJM 2023). Early high-grade (gr) cytopenias and severe infections have been reported post-CAR T cell infusion (Logue Blood 2022, Thibaud Blood 2022), and persistent cytopenias and infections can pose clinical challenges in pt care. In this safety analysis of KarMMa-3, we report frequency, kinetics of occurrence, and management of cytopenias and infections post-Tx with ide-cel or std regimens. Methods This international, randomized, multicenter phase 3 trial enrolled pts with RRMM who received 2-4 prior Txs (an IMiD agent, a PI, and daratumumab) and were refractory to the last Tx. Pts were randomized 2:1 to ide-cel or a std regimen (DPd, DVd, IRd, Kd, or EPd) selected by investigator based on prior anti-MM Tx. In the ide-cel arm, pts could have ≤ 1 cycle of optional bridging Tx (BTx) for disease control. Treated population (pop; ide-cel: pts who received leukapheresis [LA], BTx, lymphodepleting chemotherapy, or ide-cel; std regimens: pts who received any dose of study Tx) was used to assess adverse events (AEs), gr 3/4 AEs, and serious AEs. Safety pop (pts who received ide-cel or any dose of std regimens) was used to assess treatment-emergent AEs, AEs of special interest, investigator-identified neurotoxicity/cytokine release syndrome and others. In pts who had documented disease progression on std regimens and then underwent LA to receive ide-cel, only AEs before LA were included. In this analysis, incidence of cytopenias and infections at various time intervals and management, types of infections, and incidence of hypogammaglobulinemia (HGG) were assessed. Results At data cutoff (Oct 3, 2022), median follow-up was 24.1 (range 5.9−41.0) mo in the 386 randomized pts. In the treated pop, 248/249 (99.6%) vs 124/126 (98.4%) pts had any-gr AEs, 234 (94.0%) vs 96 (76.2%) had gr 3/4, and 36 (14.5%) vs 9 (7.1%) had gr 5 in ide-cel vs std regimens arms, respectively. Of the gr 5 AEs, 18/36 and 3/9 had verbatim terms consistent with progressive disease. In the safety pop, incidence of gr 3/4 cytopenias with ide-cel were higher early after infusion but generally resolved over time (196 [87.1%] pts at &lt; 3 mo, 52 [24.1%] pts at 3−&lt; 6 mo, 30 [14.7%] pts at ≥ 6 mo; Table 1) vs std regimens, which showed lower rate of resolution over time. More pts in the ide-cel (16 [7.1%]) vs std regimens arms (3 [2.4%]) had any-gr febrile neutropenia. Cytopenias were mainly managed using colony-stimulating factor in both arms (55.5% and 58.7%, respectively); RBC (48%) and platelet transfusions (32%) were more common in the ide-cel arm. Overall, incidence of gr 3/4 infections was high at &lt; 3 mo and remained consistent over time in both arms (ide-cel: 17 [7.6%] pts at &lt; 3 mo, 18 [8.3%] pts at 3−&lt; 6 mo, 13 [6.4%] pts at ≥ 6 mo; Table 2). Any-gr bacterial infections were more common in the ide-cel vs std regimens arms with higher incidence at &lt; 3 mo (10% vs 6%) but lowered at later timepoints. Incidence of gr ≥ 3 viral infections remained low and consistent with time; fungal infections were uncommon. Deaths due to infections occurred in 3 (1.3%) vs 1 (0.8%) pts at &lt; 3 mo, 0 pts at 3−&lt; 6 mo, and 7 (3.4%) vs 2 (2.6%) pts at ≥ 6 mo in the ide-cel vs std regimens arms, respectively. Indence of any-gr new HGG was higher in the ide-cel vs std regimens arms but decreased over time: 15 (6.7%) vs 2 (1.6%) pts at &lt; 3 mo, 3 (1.4%) vs 1 (0.9%) at 3−&lt; 6 mo, and 5 (2.5%) vs 0 at ≥ 6 mo, respectively; of these, 13 (5.8%) vs 1 (0.8%), 2 (0.9%) vs 1 (0.9%), and 5 (2.5%) vs 0 pts received IV immunoglobulin replacement Tx at the respective time intervals. Incidence rate (% per 100 pt-years, 95% CI) of second primary malignancies remained low and similar between arms (ide-cel, 4.0 [2.4−6.7]; std regimens, 4.4 [1.9−10.7]). Conclusion In KarMMa-3, most severe cytopenias associated with ide-cel occurred early, with a low incidence of prolonged cytopenias; all were largely manageable. Any-gr bacterial infections decreased over time while viral infections remained the same. No new safety concerns were identified for ide-cel; safety profile was consistent with previous reports. Study support 2seventy bio and Celgene, a Bristol-Myers Squibb Company.

Background: For patients with chronic lymphocytic leukemia (CLL)-the most common form of leukemia in older adults-equitable access to care is particularly challenging, as the disease is often diagnosed in community cancer centers encumbered by regional disparities. Therefore, identifying and understanding regional barriers to care is essential. In 2020, the Association of Community Cancer Centers (ACCC) developed a heat map detailing the incidence rate of CLL diagnoses across the country (Fig.1), overlayed with the locations of CLL “expert” providers, revealing the areas in the US most in need of additional CLL clinical expertise (Fig. 2). In 2022, these incidence rates were stratified by race, ethnicity, and metropolitan statistical area to identify disparities Building on these maps, ACCC set out to identify specific regional challenges to appropriate, equitable care for patients with CLL. Methods: As part of an independent education program, ACCC initiated conversations with providers about the regional barriers that patients with CLL face. Through 4 webinars in February 2023, participants from 4 regions-Northeast (New York and Maine), Northwest (Montana and Idaho), Midwest (Wisconsin, Illinois, and Iowa), and Southwest (Texas)-shared insights on challenges and exchanged ideas on strategies to improve care for patients with CLL. In addition, ACCC interviewed 3 regionally diverse cancer programs (from the US Northwest, South, and Southwest regions) that are effectively overcoming regional challenges to reach their patient populations and provide equitable care. These interviews highlighted barriers and challenges, showcased effective outreach campaigns, and explored how the outreach improved the patient journey. Findings: The following themes emerged as key challenges and potential solutions throughout all regions studied: (1) Comprehensive Diagnostic Work-up Before Treatment Initiation: A key component in caring for patients with CLL is identifying certain disease related criteria prior to formulating a treatment plan. This includes determining the disease burden, disease-related symptoms, and if the patient meets certain active disease criteria (eg, Binet Stage C or Rai Stage III or IV). Further, by utilizing genetic testing, such as the TP53 gene mutation and IGHV mutation tests, physicians can estimate time to treatment and choice of specific novel targeted therapies. (2) Understanding Patient Population Needs: Cancer programs must understand the needs of their unique patient populations to effectively address them. For example, in the Northwest, as mountainous passes can make travel dangerous at times, one local program utilizes near-campus housing/hotel space for patients for the duration of their intensive treatment. In the Southwest, addressing health insurance coverage, low health literacy, language barriers, patient-provider mistrust, and culturally competent care for undocumented individuals presents challenges to equitable care delivery. Therefore, cancer programs in this region have implemented protocols to utilize community and social services to help support these patients. (3) Developing Community Partnerships: As the median age of diagnosis with CLL is approximately 70 years old, barriers such as transportation availability, caregiver support and financial constraints could be magnified. Building trust, particularly among vulnerable communities, also presents a significant challenge. By partnering with community outreach organizations, programs can help address these issues through community resources such as ride share programs, transportation vouchers, and financial assistance programs. (4) Provider Education and Learning: Because many patients are diagnosed in community cancer programs and smaller practices where physicians do not often have experience with CLL, nationally available provider education on new developments in testing and treatments is key. Conclusions: ACCC identified regional challenges and solutions to appropriate and equitable care for patients with CLL, including the importance of comprehensive diagnostic work-up before treating, understanding the regional needs of patient populations (particularly underserved populations), building community partnerships, and engaging in targeted provider education.

Introduction: Most induction regimens for multiple myeloma (MM) contain bortezomib. In most clinical trials, bortezomib has been prescribed either intravenously or subcutaneously twice per week in 21-day or 28-day cycles. However, several retrospective single-center studies have shown that once-weekly bortezomib has comparable efficacy and less peripheral neuropathy compared to twice-weekly bortezomib ( Sidana et al, PLoS One 2017; Cook et al, AJH 2021). These findings have also been confirmed by a secondary analysis of data from three prospective Phase 3 randomized studies ( Mateos et al, Haematologica 2014). As such, many clinicians have adopted once-weekly bortezomib regimens in routine care in the past decade. However, the real-world (RW) prevalence and efficacy of once-weekly vs twice-weekly bortezomib regimens in a larger population have not yet been characterized. Methods: This study used US nationwide longitudinal Flatiron Health electronic health record-derived de-identified data. We included patients aged 18-70 years with newly diagnosed MM between 2017-2022 with ≥ 6 months of follow-up and ≥ 2 clinical visits who were treated with a first-line (1L) bortezomib-containing regimen. Patients aged &gt;70 were excluded a priori given the likelihood of altered practice patterns and more frequent comorbidities. Twice-weekly bortezomib was defined as patients for whom the most frequent interval between two doses of 1L bortezomib within a cycle was 3.0-4.9 days, while once-weekly bortezomib was defined as a corresponding interval of 5.0-9.9 days. We used multivariable logistic regression to assess demographic and clinical factors associated with once-weekly vs twice-weekly (reference) bortezomib. RW progression free survival (rwPFS) and RW overall survival (rwOS) from 1L treatment initiation were estimated using the Kaplan-Meier method. Outcomes were compared using Cox proportional hazards model including transplant as a time-varying covariate and adjustment for other demographic and clinical factors. Results: Of 2,522 patients included, 927 (36.8%) received twice-weekly while 1,522 (63.2%) received once-weekly bortezomib. Approximately half of patients (50.3%) were non-Latinx White, 21.7% non-Latinx Black, and 8.0% Latinx. Most patients were treated in the community setting (78.8%). Rates of once-weekly bortezomib administration were 66.2% and 62.1% among patients treated at academic and community practices, respectively. The frequency of weekly bortezomib use increased over time, from 58.0% between 2017-2019 to 68.8% between 2020-2022. In multivariate analysis, ECOG PS ≥ 2 (odds ratio [OR] 1.50; [95% CI 1.14 to 1.99] vs ECOG PS 0), and more recent year of diagnosis (OR 1.14; [95% CI 1.08 to 1.20] per year) were associated with higher odds of receiving once-weekly bortezomib. Conversely, Latinx patients vs non-Latinx White (OR 0.60 [95% CI 0.44 to 0.82]) and patients with ≥ 2 high-risk cytogenetic abnormalities (HRCA) vs 0 HRCA (OR 0.66 [95% CI 0.48 to 0.91]) had lower odds of receiving once-weekly bortezomib administration. No significant associations were found between gender, ISS stage, practice setting, insurance category, or baseline creatinine. There was no statistically significant difference in rwPFS among patients receiving once-weekly (median 37.3 months, 95% CI 33.8 to 42.5) vs twice-weekly bortezomib (median 39.2 months, 95% CI 32.9 to 42.8) (HR 0.87 [95% CI 0.77 to 1.00]) (Figure 1A). Similarly, there was no statistically significant difference in rwOS with median 25.5 months follow-up (Figure 1B). Median rwOS was not reached in either group (hazard ratio 0.89 [95% CI 0.75 to 1.07]). Discussion: We evaluated US bortezomib prescribing patterns for the first time in the modern era using a large nationwide RW-study. Whereas prescribing patterns have shifted towards once-weekly bortezomib over time, over 30% of patients diagnosed in the last three years received twice-weekly bortezomib. Importantly, once-weekly and twice-weekly bortezomib performed comparably with regard to rwPFS and rwOS. While our study did not analyze neuropathy or patient quality of life, once-weekly bortezomib is known to be associated with less neuropathy and less time in clinic. These data further support the conclusion that once-weekly bortezomib should be considered the standard of care for newly diagnosed patients with MM.

Introduction Secondary central nervous system (CNS) involvement develops in 2-10% of large B-cell lymphoma (LBCL) cases. Current treatment approaches for relapsed or refractory CNS disease generally do not provide durable responses. Limited data suggest efficacy and feasibility of CAR-T therapy in SCNSL. We report here the largest multicenter retrospective analysis of the safety and efficacy of CD19-directed CAR-T therapy in SCNSL patients. Methods This study included SCNSL patients who received commercial CD19-directed CAR-T therapy at 9 academic institutions in the United States between 2016 and 2022. SCNSL was defined as history of parenchymal and/or leptomeningeal/cerebrospinal fluid (CSF) involvement by lymphoma at any time prior to receiving CAR-T therapy. Systemic response was assessed using the Lugano criteria while CNS response was assessed as per International PCNSL Collaborative Group criteria. Kaplan-Meier curves were generated for progression-free survival (PFS) and overall survival (OS) for entire cohort, as well as subsets of patients with and without active CNS disease at the time of CAR-T infusion. Results Ninety patients were included in the analysis, with baseline characteristics shown in Table 1. CAR-T products utilized include axicabtagene ciloleucel (n= 38, 42%), tisagenlecleucel (n=37, 41%) and lisocabtagene maraleucel (n= 15, 14%). Fludarabine/cyclophosphamide was used as lymphodepletion in 84 patients (93%). 28 patients received CNS directed radiation therapy (RT) prior to CAR-T infusion (31%) within a median time of 28.5 days (range 5 - 906) from last day of RT. Amongst all patients at the time of CAR-T infusion 82 (91.1%) had active CNS and/or systemic involvement while 8 (8.9%) had no evidence of disease; 68 (75.5%) had active CNS involvement while 22 (24.5%) had a prior history of CNS involvement but no active at the time of CAR-T infusion. ( Table 1) Median follow up all patients was 0.5 year (range 0.01 - 4.7). 71 patients (79%) developed cytokine release syndrome (CRS; median time to onset 3 days) with 3.3% patients developing Grade 3-4. Immune effector cell-associated neurotoxicity syndrome (ICANS; median time to onset 5 days) was reported in 55 patients (61%), with 28.8% developing Grade 3-4. No patients died due to CRS or ICANS. At 1-month post CAR-T, 80 patients were evaluable for CNS response and 71 patients in the entire cohort were evaluable for systemic response. Similarly, at 3-months these numbers were 66 and 60, respectively. Objective response rates (ORR) were 75% and 80% at 1-month for CNS and systemic disease respectively, while corresponding ORRs at 3-months were 68% and 76.7%. At 1- and 3-months timepoint 36 (45%) and 33 (50%) patients, respectively achieved CNS complete remission (CR), while 44 (62%) and 42 (70%) patients respectively achieved systemic CR. 1- and 2-year PFS for entire cohort were 25% (95%Cl 15% - 34%) and 16% (95%Cl 8.5% - 28%) respectively, while 1- and 2-year OS were 46% (95%Cl 36% - 59%) and 31% (95%Cl 22% - 46%). Non-relapse mortality (NRM) were 4.6% (95%CI, 1.8% -12%) and 7.2% (95%CI 2.9% - 18%) at 1- and 2-year. Cumulative incidence of relapse at 1- and 2-year were 73% (95%Cl 63% - 83%) and 77% (95%Cl 68% - 88%), respectively. ORRs for CNS response in patients with active CNS disease at 1-month and 3-month interval were 71% (n=45) and 60% (n=31). Similarly, ORR for systemic response with active CNS disease at 1-month and 3-month interval were 85% (n=43) and 74.3% (n=32).The 2-year PFS for patients with and without active CNS disease at CAR-T infusion were 12% (95%Cl 5.4% - 27%) and 28% (95%Cl 12% - 65%) respectively, with a corresponding OS of 25% (95%Cl 15% - 41%) and 58% (95%Cl 37% - 91%). ( Figure 1) The 2-year NRM rates for patients with and without active CNS disease at CAR-T infusion were 4.6% (95%Cl 1.5% - 14%) and 14% (95%Cl 3.6% - 53%) respectively, while the cumulative incidence of relapse in similar order were 83% (95%Cl 73% - 95%) and 58% (95%Cl 39% - 88%). Conclusion In this largest known case series to date, CAR-T therapy appeared safe and feasible in patients with SCNSL, but is associated with high rates of treatment failure, particularly in patients with active CNS disease at CAR-T infusion. This warrants further study of optimal CNS-directed treatment strategies prior to CAR-T, development of novel cellular therapy platforms or consideration of post CAR-T maintenance therapy in these high-risk patients.

Background: Despite the development and approval of effective therapies for multiple myeloma (MM), MM remains an incurable disease. Moreover, patients with high-risk cytogenetics, like translocation t(4;14), continue to have a poor prognosis compared to standard-risk patients. No novel agents have been approved specifically for this population. There remains an unmet need for precision therapies for MM that can target specific drivers of high-risk MM like t(4;14). Multiple myeloma SET domain-containing protein (MMSET) overexpression observed in 100% of patients with t(4;14) acts through the MMSET-H3K36me2 axis, which promotes malignant transformation through regulation of multiple oncogenic programs. KTX-1001, a methyl transferase inhibitor, is a novel, first-in-class, potent, oral, small molecule that inhibits MMSET and the methylation of lysine K36. KTX-1001 had favorable drug-like properties, demonstrated in vivo activity, and was well tolerated in non-clinical studies. Based on these data, KTX-1001 is now being studied in a Phase 1 dose escalation and expansion study in relapsed and refractory multiple myeloma (RRMM). Study Design and Methods: This multi-country, Phase 1, open-label study (NCT05651932) is designed to assess the safety, tolerability, and initial clinical activity of KTX-1001. The study will also examine the recommended phase 2 dose (RP2D), pharmacokinetics (PK) and pharmacodynamics (PD). Part A of this trial includes an accelerated titration, followed by 3+3 dose escalation with backfill of cohorts for dose optimization prior to moving to Part B, which is an expansion phase at the RP2D (please see Figure 1 for study design schematic). The expansion phase will only include patients with t(4;14). KTX-1001 will be administered orally daily and given until disease progression, unacceptable toxicity, or withdrawal from the study. Estimated enrollment for Parts A and B will be approximately 60 patients. The study will enroll patients with RRMM who have received ≥3 prior lines of therapy, including a proteasome inhibitor (PI), immunomodulatory drug (IMiD), and anti-CD38 antibody. Patients must have measurable disease, be ≥18 years of age, have an Eastern Cooperative Oncology Group score of ≤2, and adequate bone marrow, liver, and kidney function. Key exclusion criteria include history of or current plasma cell leukemia, active central nervous system (CNS) disease, or active unstable cardiovascular function. The primary endpoints of safety and tolerability include incidence of dose-limiting toxicity (DLTs), treatment-emergent adverse events (AEs), and treatment-related AEs. Secondary endpoints include plasma concentrations of KTX-1001 and efficacy outcomes such as objective response rate (ORR), duration of response (DOR), progression-free survival (PFS), and overall survival (OS). Exploratory biomarker and pharmacodynamic assessments will also be performed. The sample size was not determined by formal statistical methods but will be sufficient to provide preliminary information on safety, PK, PD, and efficacy. Statistical analyses will be primarily descriptive. Conclusion: This Phase 1 study will evaluate a potential treatment for RRMM utilizing KTX-1001, which is a novel, first-in-class, potent, oral small-molecule MMSET inhibitor. The study is open and actively enrolling patients at centers in the United States, Spain, France, and Canada.