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Introduction: Talquetamab (Talq) is a GPRC5D targeting bispecific antibody recently approved for the treatment of relapsed refractory multiple myeloma (MM) based on the MonumenTAL-1 study. Real World Evidence (RWE) is needed to understand the safety and efficacy of Talq in patients treated outside of a clinical trial as they may have different outcomes and toxicities. Here we report outcomes of 118 patients treated with Talq. Methods: Patients treated with standard-of-care Talq were included. Data was collected through a retrospective chart review from 01/2023 until 7/2024 from 7 International Myeloma Foundation (IMF) associated MM academic centers. Results: 118 patients were included in the analysis. The median age was 64, 37% had HR disease, 22% had EMD at presentation. The median LOT was 6, median number of immunotherapies before TAL was 2 (range 1,4) and 71% received prior BCMA therapy. 72% were triple refractory and 44% were penta refractory. 25% (n=60) would not have been eligible for TAL clinical trial due to exclusion criteria and15% had an ECOG of 2 or greater. 18% (n=97) received TAL as an outpatient and the median number of hospital days was 9 (0,37) for inpatients. CRS during Step up Dose (SUD) 1 was present in 30% Gr 1 (57%), Gr2 (11%), Gr 3 (6%), CRS during SUD 2 was present in 31%, Gr 1 (65%), Gr 2 (11%), CRS during SUD 3 when administered was present in 14% , Gr 1 (82%), Gr 2 (6%) and with first full dose was 12% , Gr 1 (71%), unknown (29%). ICANS occurred in 6% (7/97), Gr 1 (14%), Gr 2 (29%), Gr 3 (14%) and unknown in 43% there was no evidence of HLH. Skin toxicity was present in 62% of patients (n=105/118) with 4% needing dose interruptions and presented as rash (20%), dryness (42%) and itching (20%). Nail toxicity was present in 20% (n=65/118), with 9% needing dose interruptions. Dysgeusia was present in 51% (n=97/118), with 10% needing dose interruptions. Oral toxicity manifest as stomatitis (10%), glossitis (1%), ulcerations (2%), dry mouth (27%), was present in 34% (n=61/118), with 12.5% needing dose interruptions. Infections were present in 34% (n=82/118) and CMV reactivation in 23% while only 1 patient needed treatment for CMV. The Overall Response Rate (ORR) was 64.9% with a VGPR rate or higher of 43.3% in this population. Updated efficacy data including PFS will be reported at the time of presentation Conclusions: This is the first largest RWE of the safety and efficacy of Talq in a heavily pretreated population with a high prior BCMA exposure. The ORR is consistent with a prior study by Jakubowiak et al which showed an ORR OF 65.7% after prior T cell engagers. The safety profile - CRS, ICANS, skin and oral toxicities was similar to the MonumenTAL study, CMV reactivation was higher and this may be related to treatment with prior immunotherapies and should be monitored in the future. This report shows that Talq has a similar safety and efficacy profile in the real world when sequenced after prior BCMA therapies.

Background: The COVID-19 pandemic had an outsized impact on individuals with immune compromise, such as multiple myeloma, leading to increased rates of severe COVID, hospitalization, and death in these groups. The pandemic also demonstrated the need for rapid and efficient evidence generation to address rapidly changing medical needs and accelerated the use of innovative trial designs to accomplish this goal. Methods: We designed and established a prospective, decentralized study within a site-based provider network, COVID-19 OutcomeS in Myeloma and the Impact of VaCcines (COSMIC), for patients with multiple myeloma at ASH Research Collaborative sites to monitor outcomes related to COVID-19 infection and vaccination. The direct-to-patient approach was accomplished using a study application accessed with a QR code provided to patients during usual clinical care. All study activities occurred within the patient portal at Baseline, Day 30, and Day 180, minimizing burden on site personnel and staff. Study activities included eligibility confirmation, consenting, electronic health record (EHR) data permissions, and patient-reported outcome (PRO) surveys. PRO data (EORTC QLQ-C30, EORTC QLQ MY-20) were made available to clinicians through the portal to visualize results from their patients. Patients shared if they received a COVID-19 vaccination or booster and if they had a COVID-19 infection. Patients with a history of COVID-19 infection included method of confirmation and if hospitalization was required. Patients were provided compensation for participation. Automated text and email messages were sent at three separate intervals: 24 hours, Day 8, and Day 15 for participants who initiated but did not complete study activities. A personal email reminder per participant was sent for those whose second study visit window was approaching. ASH Research Collaborative clinicians met regularly to share best practices related to enrollment and study conduct, thereby creating an innovative evidence generation learning community. We studied the feasibility of data collection in a decentralized format by focusing on the number of participants who interacted with the system, those who consented, and those who completed baseline PRO assessments. Results: The COSMIC study rapidly accrued and consented 200 patients from eight participating ASH Research Collaborative sites over four months (1/22/2024 through 5/17/2024): 69% self-reported as non-Hispanic White (NHW). Of enrolled participants, 57.5% opted to permission sharing of their EHR data, which included disease and treatment-related clinical data, laboratory results, pathology reports, and imaging reports. A total of 196 patients (98%) provided demographic and COVID-related disease and vaccine data at baseline; nearly all of these patients (n=195) provided baseline PRO data, and 150 patients provided further information at Day 30 at the time of this analysis. Those who did not provide Day 30 data were not significantly different from those who did in terms of age (median: 68 [no Day 30 data] vs. 67 [Day 30 data] years; p=0.44), sex (41% [no Day 30 data] vs. 47% [Day 30 data] Female; p=0.47), or race (65% [no Day 30 data] vs. 71% [Day 30 data] NHW; p=0.60). A higher proportion of Hispanic patients were retained at Day 30 (13/15=87%) vs. 78% of non-Hispanic patients or those who declined reporting ethnicity (2/7=29%; p=0.007). COVID-19 vaccination data were submitted by 196 patients, 186 of whom had ever received a COVID-19 vaccination. Data on number, type, brand, and dates for these vaccinations were provided. Conclusions: The COSMIC study conducted by the ASH Research Collaborative was able to rapidly accrue a diverse cohort of patients using a decentralized workflow within a site-based provider network, with high consent and compliance rates. This platform, and the innovative evidence generation learning community of ASH Research Collaborative investigators and patients, sets a precedent to address a variety of real-world questions related to disease management, infections, vaccinations, and PROs in this population of patients with multiple myeloma.

Background: Data from the ASH Research Collaborative COVID-19 Registry for Hematology demonstrated that patients with multiple myeloma and other immune compromise had elevated risk for severe complications from COVID-19 infection. To address current evidence gaps and to demonstrate proof of concept for a pandemic preparedness and response network, the ASH Research Collaborative Multiple Myeloma Program developed a prospective, decentralized study within a site-based provider network to investigate COVID-19 infections, vaccinations, and quality of life in patients with multiple myeloma. Methods: We designed and established the COVID-19 OutcomeS in Myeloma and the Impact of VacCines (COSMIC) to study COVID-19 in patients with multiple myeloma at ASH Research Collaborative network sites. A study application was accessed with a QR code and shared with patients during usual clinical care. Patients provided consent, optionally gave permission for electronic health record data collection, and completed patient-reported outcomes (EORTC QLQ-C30 and MY20) at baseline, Day 30, and Day 180 through the study portal. Clinicians at participating sites facilitated study enrollment and shared best practices monthly to accelerate study execution. Study objectives related to feasibility of data collection in a decentralized format are reported in a separate abstract. Here, we report interim results related to SARS-CoV-2 vaccination history, COVID-19 infection, and how these relate to patient reported outcomes and clinical outcomes in enrolled participants. Results: The COSMIC study rapidly accrued and consented 200 patients from eight participating ASH Research Collaborative sites over four months (1/22/2024 through 5/17/2024). Consented participants' ages ranged from 29 to 93 years, with median of 67 years; 46% were female, 69% were non-Hispanic White (NHW), 17% were non-Hispanic Black (NHB), and 8% were Hispanic/Latino. Of the 196 patients who reported COVID-19 data, 111 (57%) reported at baseline that they had a history of COVID-19 infection, with 12 having required hospitalization for this (12/111=11%). Overall, 95% (186/196) reported a history of COVID-19 vaccination, where the median number of vaccinations was 4 (range: 1 to 6); 44 patients (23%) expressed willingness to discuss getting a yearly booster vaccine with their provider. At 1-month follow-up, there were 3 additional patients who reported a COVID-19 infection and 18 patients who received an additional COVID-19 vaccination. The baseline EORTC QLQ-C30 median Global Health Status/QOL score was 66.7 (mean=64.4, range: 8.3 - 100, n=196). This overall global QOL score was not significantly different between those who did vs. did not have a history of COVID-19 infection (mean [SD]: 63.7 [19.3] vs. 65.8 [17.6]; p=0.57). In analyses adjusted for age, biological sex, and race/ethnicity group, history of COVID-19 infection was not associated with HRQOL (odds ratio=0.93, 95% CI: 0.78 - 1.10; p=0.38). Data collection is ongoing and final study results will be reported at a later date. Conclusion: COSMIC is a prospective, decentralized study within a site-based provider network conducted by the ASH Research Collaborative Multiple Myeloma Program that demonstrates the feasibility of using an innovative evidence generation strategy to drive rapid accrual of patients to address a rapidly evolving area of need. The COSMIC study also provides proof of concept that a real-world evidence generation network can play an important role in national pandemic preparedness and response. The COSMIC experience reinforces the ability to accrue diverse patient populations representing the demographic of myeloma patients in the US.

Introduction: Frailty is known to be an important risk factor for adverse outcomes in multiple myeloma (MM) and is often under-represented in clinical trials. Frail patients are known to have increased toxicity, high rates of treatment discontinuation rates and decreased efficacy including worse overall survival in MM. Teclistamab (TEC) is a bispecific BCMA-CD3 directed T-cell antibody (BsAb) that was approved based upon the pivotal MajesTEC-1 study showing high overall response rates in patients with R/R MM. In MajesTEC-1, the median age was 63, and patients with ECOG ≥ 2 were excluded, suggesting that the vast majority of patients in the trial were fit. There is a paucity of data both in clinical trials as well as in the real-world regarding the outcomes of patients, particularly frail patients, with BsAb. This data is needed to both understand current outcomes of frail patients as well as devise strategies for future optimization with BsAb treatment. We performed a retrospective analysis utilizing the International Myeloma Foundation (IMF) immunotherapy database with the objective of understanding the outcomes of older adults (age ≥ 70) including frail patients treated in the real-world with teclistamab. Methods: Data was collected from 7 individual academic sites for patients aged ≥ 70 years treated with teclistamab in the real-world. Data collected include patient demographics, disease characteristics, as well as efficacy and toxicity associated with teclistamab. Frailty score was retrospectively calculated using the simplified/IFM frailty index which includes chronological age, ECOG PS and Charlson Comorbidity Index categorizing the patients into fit (score 0-1) or frail (≥ score 2). Fisher's exact tests were performed to evaluate differences in outcomes between fit and frail patients. Results: A total of 81 pts were included in our total cohort. The median age was 76 year (range 70-91). Among them, 44 (54%) were > age 75 and 23 (28%) > age 80. Twenty-eight (35%) patients had an ECOG performance status of ≥2. Using the simplified/IFM frailty index, 22 (27%) were classified as fit and 59 (73%) were frail. In the frail subgroup, a high proportion of patients (42%) would be classified as ultra frail (frailty score of ≥3). Selected baseline patient and disease characteristics are as follows: high risk cytogenetics including 1q gain/amp (fit 67% vs frail 43%), median prior lines (fit 7 vs frail 5), triple class refractory (fit 81% vs frail 88%), CrCl <30 (fit 5% vs frail 15%). For patients hospitalized for step-up dosing, median number of hospital days was 8 both in the fit and frail group. All grade CRS was noted in 12 (55%) fit and 28 (47%) frail patients. Among the fit patients, only 1 of the 12 patients (8%) had grade 2 CRS, whereas 8 of 28 (29%) frail patients had grade 2 (p-value=0.23). ICANS was reported in 2 (9%) fit patients and 8 (14%) frail patients (p=0.72). The majority of ICANS was grade 1 in both groups, but among the frail group, there was one grade 3 and two grade 4 ICANS cases reported. Infections were reported in 10 (45%) fit patients and 35 (59%) frail patients (p=0.32), with 2 (9%) and 14 (23%) being grade≥3 (p-value=0.21). IVIG was administered in most patients (fit 50% vs frail 58%, p=0.62). Grade 3/4 neutropenia was reported in 10 (45%) fit patients and 19 (32%) frail patients (p=0.30). The overall dosing interval was changed in 32% of fit patient and 34% of frail patients (p=1.00). The overall response rate was 50% for fit patients versus 66% for frail patient (p=0.61). The type of responses noted in the fit patient were as follows: sCR/CR 18%, VGPR 27%, PR/MR 5%, SD 18%, PD/NE 32% and for frail patients : sCR/CR 18%, VGPR 43%, PR/MR 9%, SD 5%, PD/NE 25%. The median follow-up time was 13.1 months. 12-month PFS for fit pts was 47.6% (95% CI 25.7% - 66.7%) and for frail pts 42.4% (29.0% - 55.3%). 12-months OS for fit pts was 64.9% (95% CI 39.9% - 81.6%) and for frail 61.5% (47.0% -73.1%). Conclusions: This is the first real-world study to evaluate the outcomes of teclistamab in frail older adults. With regards to toxicity, frail older adults showed a trend towards higher rates of ≥ grade 2 CRS, ≥ grade 2 ICANS as well as ≥3 grade infections. Efficacy was maintained in both fit and frail older adults similar to the MajesTEC-1 study. Our study highlights that BCMA BsAb can be safely utilized in older adults including frail older adults; however, additional proactive supportive care may be required to further optimize outcomes.

Introduction. Ciltacabtagene autoleucel (cilta-cel) and idecabtagene vicleucel (ide-cel), two anti-B-cell maturation antigen (BCMA) CAR T therapies, have demonstrated remarkable responses and improved survival among patients with relapsed/refractory multiple myeloma (RRMM) in the clinical trials and standard of care (SOC) setting. Here, we compare safety, efficacy, and survival for patients treated with SOC ide-cel and cilta-cel. Methods. Data were from a retrospective chart review of RRMM patients leukapheresed by 12/31/2022 with the intent to receive SOC ide- or cilta-cel at 19 institutions in the US Multiple Myeloma Immunotherapy Consortium. An inverse probability of treatment weighting (IPTW) approach was used to compare outcomes by therapy type (cilta- vs. ide-cel), balancing on age, sex, race and ethnicity, performance status, extramedullary disease, high-risk cytogenetics, prior BCMA therapy, bone marrow plasma cells, penta-refractory status, lymphodepleting chemotherapy, baseline ferritin, low cell dose, and bridging therapy response. Logistic regression and Cox proportional hazard models were used to examine the association of treatment type with safety, efficacy, and survival accordingly, while adjusting for IPTW weights. We employed propensity score matching utilizing the same covariates to identify the association of treatment type with progression-free survival (PFS) within relevant patient sub-groups. Results. A total of 641 patients were leukapheresed by 12/31/2022 with ide-cel (n=386) and cilta-cel (n=255). 586 patients were infused (n=350 for ide-cel; n=236 for cilta-cel) with a median follow-up of 13.0 and 12.6 months, respectively. After IPTW, patient characteristics were well-balanced. Patients treated with cilta-cel were more likely to have grade ≥ 3 cytokine release syndrome (CRS) (OR=5.52, 95% CI=1.76-17.30, p=0.004), infections (OR=2.07, 95% CI=1.44-2.97, p<0.001), and delayed neurotoxicity (NT) (OR=20.97, 95% CI=4.75-92.42, p<0.001) compared to patients treated with ide-cel. In the cilta-cel cohort, 24 patients (10%) experienced delayed NT compared to 2 patients (1%) in the ide-cel cohort. Although not statistically significant, patients treated with cilta-cel were more likely to have any second primary malignancies (SPMs) (OR=1.87, 95% CI=0.94-3.71, p=0.08) and any SPMs excluding non-melanoma skin cancers (OR=1.78, 95% CI=0.78-4.10, p=0.2) but no association was observed for odds of hematologic SPMs (OR=0.98, 95% CI=0.26-3.61). No association was observed for therapy type with any or severe immune effector cell-associated neurotoxicity syndrome, any CRS, severe cytopenias, and non-relapse mortality. Compared to ide-cel, cilta-cel was associated with better treatment responses of ≥ complete response (OR=2.38, 95% CI=1.61-3.51, p<0.001) and ≥ partial response (OR=1.74, 95% CI=0.99-3.05, p=0.06). Patients treated with cilta-cel had a longer PFS and overall survival (OS) than ide-cel (HR=0.47, 95% CI=0.35-0.62, p<0.001 and HR=0.63, 95% CI=0.42-0.93, p=0.02, respectively), and these findings were similar in the intention to treat cohort (PFS: HR=0.44, 95% CI=0.34-0.55, p<0.001; OS: HR=0.55, 95% CI=0.41-0.73, p<0.001, respectively). We observed consistent findings when repeating the analyses restricting the ide-cel cohort to patients infused during the same time-period as FDA approval for cilta-cel (≥ March 2022), restricting to patients with data on all covariates, and restricting to sites that contributed data for both products. In a propensity matched population, (n=380; n=190 for cilta-cel and n=190 for ide-cel), patients treated with cilta-cel had superior PFS compared to those treated with ide-cel in most subgroups with respect to age and disease characteristics including extramedullary disease, high-risk cytogenetics, and elevated baseline ferritin (p<0.05). Conclusion. Our results suggest superior efficacy of cilta-cel with a higher incidence of certain toxicities compared to ide-cel in the SOC setting. This study provides valuable information for patient counseling and guiding the selection of CAR T-cell therapy for specific patient populations. Further validation through similar large-scale real-world experiences or prospective studies is needed to confirm our results and enhance applicability in the clinical setting. *DH, LP, & DD are co-first authors * YL, KP, & SS are co-last authors

Abstract Ciltacabtagene autoleucel (cilta-cel) was approved in 2022 for patients with relapsed/refractory multiple myeloma (RRMM). We report outcomes with cilta-cel in the standard-of-care setting. Patients with RRMM who underwent leukapheresis for cilta-cel manufacturing between 1 March 2022 and 31 December 2022 at 16 US academic medical centers were included. Overall, 255 patients underwent leukapheresis and 236 (92.5%) received cilta-cel, of which 54% would not have met CARTITUDE-1 eligibility criteria. In treated patients (N = 236), cytokine release syndrome was seen in 75% (grade ≥3, 5%), immune effector cell–associated neurotoxicity syndrome in 14% (grade ≥3, 4%), and delayed neurotoxicity in 10%. Overall and complete response rates were as follows: all patients who received cilta-cel (N = 236), 89% and 70%; patients receiving conforming cilta-cel (n = 191), 94% and 74%; and conforming cilta-cel with fludarabine/cyclophosphamide lymphodepletion (n = 152), 95% and 76%, respectively. Nonrelapse mortality was 10%, most commonly from infection. After a median follow-up of 13 months from cilta-cel, the median progression-free survival (PFS) was not reached, with 12-month estimate being 68% (95% confidence interval, 62-74). High ferritin levels, high-risk cytogenetics, and extramedullary disease were independently associated with inferior PFS, with a signal for prior B-cell maturation antigen–targeted therapy (P = .08). Second primary malignancies excluding nonmelanoma skin cancers were seen in 5.5% and myeloid malignancies/acute leukemia in 1.7%. We observed a favorable efficacy profile of standard-of-care cilta-cel in RRMM, despite more than half the patients not meeting the CARTITUDE-1 eligibility criteria.

Neutrophil accumulation is a key feature of ARDS, but their contribution to the pathogenesis is still uncertain. We investigated the effect of reducing neutrophils in a clinically relevant mouse model of pneumococcal pneumonia treated with antibiotics. When appropriate antibiotics were administered, neutrophil reduction with Ly6G antibody markedly attenuated lung injury and improved oxygenation. In the early phase of bacterial pneumonia, neutrophils contribute to the severity of lung injury, although they also participate in host defense.

The treatment of Waldenström macroglobulinemia/lymphoplasmacytic lymphoma (WM/LPL) has evolved to include several new options. The NCCN Guidelines for WM/LPL provide a framework on which to base decisions regarding diagnosis, treatment, assessment of response to treatment, and follow-up of both newly diagnosed and previously treated WM/LPL.

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.

Introduction: Lymphodepletion (LD) chemotherapy is critical for the efficacy of CAR-T therapy by eradicating immunosuppressive cells, inducing costimulatory molecules, and promoting expansion and persistence of CAR-T cells. It also can contribute to an increased risk of infections, cytopenia, and other toxicities. We evaluated the utilization of varying LD regimens used in standard-of-care (SOC) autologous B-cell maturation antigen-directed (BCMA) CAR-T therapy with ide-cel or cilta-cel for relapsed/refractory multiple myeloma (RRMM) and the effect on outcomes and toxicity. Methods: Data were retrospectively collected from patients with RRMM who underwent LD and CAR-T cell infusion by December 31, 2022, from 13 US academic institutions with SOC ide-cel or cilta-cel. Response rates and other categorical variables, specifically LD regimen, were tested for association using Wilcoxon rank-sum (or Kruskal-Wallis for three or more groups) or Fisher's exact tests, respectively. Results: A total of 523 patients were infused at the time of data cut-off with 489 patients evaluable for safety and survival analyses; 368 (75%) were infused with ide-cel and 121 (25%) with cilta-cel. The median age was 65 years old (range 30-90) with 206 females (42%) and 283 males (58%), and 13% with ECOG performance status ≥ 2 at time of LD. Fludarabine and cyclophosphamide (Flu/Cy) LD was used in 422 patients while 67 patients received other LD regimens including bendamustine-based (n = 35, 52%), cladribine-based (n = 25, 37%) or cyclophosphamide alone (n = 7, 10%). The primary reason for use of Flu/Cy LD was institutional guidance or SOC in 378 patients (90%), while the primary reason for use of other LD regimens was due to the fludarabine shortage in 65 patients (97%) with 3% citing physician's choice or institutional guidance. No significant difference was identified among response outcomes, with those receiving Flu/Cy LD achieving an ORR of 84% compared to 81% with other LD regimens (p = 0.59) and no difference observed in rates of ≥ VGPR (66% Flu/Cy LD vs 60% other LD; p = 0.48). Of those evaluable for MRD at 1 and 3 months, the MRD negative rate at 10 -6 for those with Flu/Cy LD was 77% (n= 137) and 77% (n=113) and with other LD regimens was 66% (n=35) and 79% (n=28), respectively. At a median follow-up of 9.7 months, no statistically significant difference was noted in median progression free survival (mPFS) with Flu/Cy vs other LD regimens (9.3 mos vs NR) or overall survival (OS) (19.4 mos vs NR). When stratified by type of CAR-T therapy, treatment with bendamustine-based LD was associated with an inferior mPFS compared to those receiving Flu/Cy LD in patients treated with ide-cel (3.8 vs 8.5 mos; p=0.0056), though not by multivariate analysis. Univariate analysis of patients treated with ide-cel between Flu/Cy and bendamustine LD did not reveal any significant differences in age, gender, ECOG, R-ISS stage, extramedullary disease, high-risk cytogenetics or renal dysfunction (Cr < 45 ml/min). LD regimen was not a predictor for PFS on multivariable analyses amongst patients treated with ide-cel, while ECOG ≥ 3 (hazard ratio [HR]= 4.44, 95% confidence interval [CI]= 1.40, 14.08) and t(4,14) (HR= 2.02, 95% CI=1.14, 3.59) were associated with worse PFS. No difference in mPFS by LD regimen was observed in patients receiving cilta-cel, which was a smaller cohort (mPFS: Flu/Cy 11.7 mos, bendamustine-based NR, cladribine-based NR, cyclophosphamide NR). Rates of all grade CRS (81% vs 70%), Grade ≥ 3 CRS (3% vs 3%), all grade ICANS (19% vs 12%, and Grade ≥ 3 ICANS (4% vs 2%) were similar among those receiving Flu/Cy or other LD regimens, respectively. Patients receiving Flu/Cy LD were less likely to have any grade cytopenia at 1 month (33% vs 55%, p < 0.001) and 3 months (52% vs 69%, p < 0.001), with no observed difference in infection rate. Conclusions: The fludarabine shortage experienced in the US in late 2022 necessitated the use of alternative LD regimens with BCMA-directed CAR-T therapy with most centers relying on bendamustine- or cladribine-based regimens. Use of bendamustine-based LD was associated with inferior PFS in patients receiving ide-cel on univariate analysis, but not on multivariate analysis after adjusting for other prognostic factors. In summary, there is no clear difference in efficacy or safety between Flu/Cy and non-Flu/Cy LD in patients receiving BCMA-directed CAR-T therapy. *Authors contributed equally