Dima, Danai

7508 Background: Idecabtagene vicleucel (Ide-cel) has demonstrated excellent efficacy in patients with relapsed/refractory multiple myeloma (RRMM). However, outcomes in patients with extramedullary disease (EMD) remain to be better characterized. Methods: We included patients from 11 US academic centers, who were evaluated for EMD and were infused with ide-cel between May 2021 and April 2023. Patients with soft tissue or visceral lesions non-contiguous from bony lesions were classified as having true EMD, with paraskeletal disease classified as non-EMD. Disease responses were evaluated using the IMWG criteria. Time-to-event analyses were performed from the date of ide-cel infusion. Results: Among 351 patients with RRMM treated with ide-cel, 84 (24%) had EMD prior to infusion. Median follow-up for the entire cohort was 18.2 months (95% CI: 17-19.3). Baseline characteristics at ide-cel infusion for EMD and non-EMD cohorts are depicted in the table. For the EMD and non-EMD cohorts, the Day 30 objective response rates (ORR) were 58% vs. 69% (p=0.1), Day 30 ≥complete response rates were 16% vs 24% (p=0.11), the Day 90 ORR were 52% vs 82% (p<0.001), and best ORR were 58% vs 82%, respectively. The median progression-free survival (PFS) was 5.3 months (95% CI: 4.1-6.9) for the EMD cohort vs. 11.1 months (95% CI: 9.2-12.6; p<0.0001) for the non-EMD cohort. The median duration of response for EMD among day 30 responders was 6.4 months (95% CI: 5.1-8.4). In a multivariable analysis, EMD was an independent predictor of inferior PFS [hazard ratio 1.8 (95% CI: 1.2-2.5), p<0.001] after adjusting for ECOG status, revised ISS stage, penta-drug refractoriness, elevated ferritin, prior BCMA-directed therapy and use of bridging therapy. Pattern of progression in the EMD cohort (n=68/84) included EMD site only (21%), hematologic only (22%), or both (57%), with comparable PFS for type of progression (p=0.19). The median overall survival (OS) was 14.8 months [95% CI: 9-Not reached (NR)] for EMD and 26.9 months [95% CI: 26.3 vs NR, p=0.006)] for the non-EMD group. Rates of Grade ≥2 cytokine release syndrome or neurotoxicity syndrome were comparable between the two cohorts. Conclusions: Patients with EMD demonstrate significantly inferior Day 90 ORR and presence of EMD is an independent risk factor for inferior PFS. [Table: see text]

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: 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 &lt; 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 &lt; 0.001) and 3 months (52% vs 69%, p &lt; 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

Introduction: In many cases, treatment decisions for multiple myeloma patients must be made in the absence of high quality randomized controlled clinical trials. As a result, many clinicians lean on prognostic models to drive treatment selection. The most widely used of these models incorporate a limited number of patient related factors that reflect tumor burden, cytogenetic features, or gene expression profiling. These prediction scores are derived from regression models that incorporate these variables at the time of diagnosis. They do not account for variables that change dynamically over time, do not explore the relationship between treatment selection and progression, and imperfectly predict survival outcomes. We designed a prognostic model based on an ensemble machine learning platform to predict progression in NDMM using Extreme Gradient Boosting Machine (XGBoost) combined with accelerated failure time modeling for survival analysis. Methods: We utilized a large retrospective data set containing treatment and response information for 1127 patients with newly diagnosed multiple myeloma (NDMM) treated at the Cleveland Clinic Foundation between 2000 and 2023. Following data preprocessing based on data completeness, 953 patient records were included in our training, testing, and cross validation datasets. For the purposes of our analysis, the initial dataset was randomly split into training (70%), testing (15%) and validation (15%) subsets at the patient level. We also defined the lower and upper bounds for each subset, which is critical due to the right-censored nature of survival data. Hyperparameters for XGBoost were optimized using Bayesian search, minimizing the negative log-likelihood. A random forest method was applied for the imputation of missing data (MissForest). We then trained the XGBoost model using GPU acceleration for enhanced computational efficiency. Finally, a log-rank test on predicted survival times was used to test the model's performance on patients with and without known progression. Results: Our preprocessed data set had 953 patients with a mean age at disease onset of 65 years and a slight male predominance (55%). Approximately 27% of patients harbored high cytogenetic risk disease and 3.5% of the cohort presented with extramedullary disease a diagnosis. At a median follow up of 35 months, 47% of patients had experienced disease progression or death. Induction therapy included an immunomodulatory drug in 40% of patients and proteasome inhibitors in 22%. Frontline autologous stem cell transplantation followed induction in 28% of patients. Median progression free survival in the overall data set was 44 months. These features were consistent across the randomly assigned training, testing, and validation cohorts. Following data preprocessing, 34 independent clinical and genomic variables including selection of first line treatment were assessed as model inputs each available record. Under optimized parameters, the model was trained with a maximum tree depth = 7 and a learning rate ~ 0.22 for the desired output of progression free survival (PFS). We then queried PFS for both the training and validation sets and divided patients into those known to have progressed and those without a progression event. Survival analysis was undertaken using predicted PFS values for patients known to have progressed and those who remained progression free. For the validation data set, our model successfully discerned between progressed and non-progressed cases (log-rank test statistic = 22.07, p &lt; 0.005) (Figure 1). Discussion: We present a machine learning approach based on regularized gradient boosting that accurately discerns between patients who experience progression and those who remain progression free at a median ~35 months of follow-up in a large retrospective data set in patients presenting with NDMM. Further elaboration of our model will allow for the incorporation of large amounts data to predict survival outcomes on the basis of dynamic variables such as depth of response and treatment selection. With the ability to parse outcomes among multiple myeloma patients at high resolution, future clinicians and clinical trialists may be able to overcome limitations in trial design and patient-level therapy selection for both newly diagnosed and relapsed patients.

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

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

PURPOSE Compared with people living without HIV (PWOH), people living with HIV (PWH) and cancer have traditionally been excluded from immune checkpoint inhibitor (ICI) trials. Furthermore, there is a paucity of real-world data on the use of ICIs in PWH and cancer. METHODS This retrospective study included PWH treated with anti–PD-1- or anti–PD-L1-based therapies for advanced cancers. Kaplan-Meier method was used to estimate overall survival (OS) and progression-free survival (PFS). Objective response rates (ORRs) were measured per RECIST 1.1 or other tumor-specific criteria, whenever feasible. Restricted mean survival time (RMST) was used to compare OS and PFS between matched PWH and PWOH with metastatic NSCLC (mNSCLC). RESULTS Among 390 PWH, median age was 58 years, 85% (n = 331) were males, 36% (n = 138) were Black; 70% (n = 274) received anti–PD-1/anti–PD-L1 monotherapy. Most common cancers were NSCLC (28%, n = 111), hepatocellular carcinoma ([HCC]; 11%, n = 44), and head and neck squamous cell carcinoma (HNSCC; 10%, n = 39). Seventy percent (152/216) had CD4+ T cell counts ≥200 cells/µL, and 94% (179/190) had HIV viral load <400 copies/mL. Twenty percent (79/390) had any grade immune-related adverse events (irAEs) and 7.7% (30/390) had grade ≥3 irAEs. ORRs were 69% (nonmelanoma skin cancer), 31% (NSCLC), 16% (HCC), and 11% (HNSCC). In the matched mNSCLC cohort (61 PWH v 110 PWOH), 20% (12/61) PWH and 22% (24/110) PWOH had irAEs. Adjusted 42-month RMST difference was –0.06 months (95% CI, –5.49 to 5.37; P = .98) for PFS and 2.23 months (95% CI, –4.02 to 8.48; P = .48) for OS. CONCLUSION Among PWH, ICIs demonstrated differential activity across cancer types with no excess toxicity. Safety and activity of ICIs were similar between matched cohorts of PWH and PWOH with mNSCLC.