Kort, Jeries

Abstract Introduction: Cilta-cel is a BCMA-directed CAR T-cell therapy that has shown remarkable efficacy in patients with RRMM. As real-world (RW) experience with cilta-cel continues to expand, and with the recent FDA guidance reducing the recommended proximity to the CAR T center from four to two weeks post-infusion, there is growing interest in identifying patients at low risk for severe early complications who may be safely managed in the outpatient setting and potentially ‘discharged’ home earlier. Methods Data were collected from 769 patients with RRMM treated with cilta-cel at 15 institutions in the U.S. via the Multiple Myeloma Immunotherapy Consortium.Logistic regression was used to identify predictors of patients who could be managed in the outpatient setting (low-risk group). Based on expert consensus within the Consortium, low-risk patients were defined as: grade ≤1 CRS, no ICANS, and no IEC-HS. The remaining patients were categorized as high-risk. We evaluated baseline characteristics with missingness < 20% as predictors, including age, sex, race, and ethnicity, ECOG performance status (PS) at time of lymphodepletion (LD), extramedullary disease, bone marrow plasma cell (BMPC) percentage, high-risk cytogenetics, bridging therapy including response, penta-refractory status, number of prior lines of therapy, prior anti-BCMA therapy, baseline C-reactive protein (CRP), and baseline ferritin. The cohort was restricted to patients with complete data on all predictors (n=455) and split into a training and testing cohort (80/20 split, n=364/91). Bidirectional stepwise regression was used to build the predictive model using variables with significance of p<0.15 selected for entry. The best model was selected based on the AIC (Akaike Information Criterion) and a significance level of p<0.05. Results Among the 455 patients with complete data included in the final model, 290 (64%) were categorized as low-risk and 165 (36%) as high-risk. Compared to the low-risk group, high-risk patients were more likely to have an ECOG PS ≥2 at time of LD (20% vs 9%, p<0.001), high-risk cytogenetics (47% vs 35%, p=0.009), and penta-refractory disease status (34% vs 24%, p=0.031). High-risk patients also had a higher median BMPC percentage (15% vs 5%, p<0.001), and higher baseline pre-LD CRP and ferritin. Overall response rates were high, at 95% vs 90% (p=0.047) for the low vs high risk groups, with complete response or better achieved in 73% vs 66% of patients, respectively (p=0.14). With a median follow-up of approximately 11 months, median progression-free survival was not reached (95% CI: 27-NA) in the low-risk group and 18.2 months (95% CI: 13.1-NA) in the high-risk group. In terms of safety, non-ICANS neurotoxicity (NINT) occurred less frequently in the low-risk group (6.6% vs 13%, p=0.015). Specifically, Parkinsonism was observed in 1.7% vs 6.1% (p=0.013), and cranial nerve palsy in 4.5% vs 5.5% (p=0.7), respectively. Non-relapse mortality (NRM) was lower in the low-risk group (4.2%) compared to the high-risk group (14%; p < 0.001). The most common causes of NRM in the low- and high-risk groups were acute toxicities (0% vs 36%, including CRS, IEC-HS, and ICANS), delayed toxicities (0% vs 8%, including colitis, NINT, and Parkinsonism), infections (50% vs 48%), and other unrelated causes (50% vs 8%). The best model to predict low-risk patients that could be managed in the outpatient settingincluded BMPC percentage and ECOG PS at LD. In the training cohort, patients with a higher pre-LD BMPC percentage and an ECOG PS ³2 were less likely to be in the low-risk group(OR per 1-unit change in BMPC percentage = 0.99, 95% CI=0.98-0.99, p<0.001 and OR for ECOG PS 2-4 = 0.38, 95% CI=0.20-0.72, p=0.003). The AUC for this model was 0.663 in the training cohort and 0.659 in the testing cohort. Conclusion In this large, multi-institutional cohort of patients with RRMM treated with cilta-cel, we identified clinical factors associated with lower risk for early severe toxicities, supporting outpatient administration and the potential for earlier discharge in selected patients, particularly those who are fit and have low disease burden. Our findings provide a practical framework to guide risk stratification and outpatient CAR T management strategies, particularly in light of evolving regulatory guidance and growing RW experience with cilta-cel.

Abstract Introduction: Ciltacabtagene autoleucel (cilta-cel) is a highly effective BCMA-redirected CAR T-cell therapy for RRMM. While the pivotal CARTITUDE-1 trial established a target dose of 0.75 x 10^6 CAR+ viable T-cells/kg, the approved cell dose is 0.5-1.0 x 10^6 and the optimal dosing strategy to balance efficacy and toxicity remains unclear. This question is of interest given that a dose-response association has been demonstrated for idecabtagene vicleucel (a related BCMA-directed CAR T product). It has also been hypothesized that lower doses of cilta-cel may be associated with reduced toxicity. This study aims to evaluate the association between cilta-cel dose and key efficacy and toxicity outcomes using a large, real-world dataset from the US Multiple Myeloma Immunotherapy Consortium. Methods: We conducted a multicenter, retrospective analysis of 751 RRMM patients treated with commercial cilta-cel across 15 US academic centers. The administered cilta-cel dose (million cells/kg) was categorized into four groups: low (<0.5), standard-low (0.5 to <0.6), standard (0.6 to <0.8), and standard-high (0.8 to 1.0). We compared incidence rates of cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), delayed neurotoxicity (DNT), and immune effector cell-associated hemophagocytic lymphohistiocytosis-like syndrome (IEC-HS) across these dose categories using logistic regression. Best response rates and progression-free survival (PFS), estimated using the Kaplan-Meier method, were also compared, with differences assessed using the log-rank test for the latter. Results presented are derived from multivariable models adjusting for extramedullary disease, ECOG status, penta-refractory disease and receipt of bridging therapy. Results: Among 751 infused patients, the dose distribution was: <0.5 (n=33), 0.5 to <0.6 (n=131), 0.6 to <0.8 (n=550), and 0.8 to 1.0 (n=37). The four dose groups were well-balanced in terms of baseline patient and disease characteristics, including age, high-risk cytogenetics, and extramedullary disease, with the exception of t(14;16), which was more common in the standard-low and standard dose groups (p=0.006). There were no statistically significant differences in the rates of any grade CRS (p=0.11), any grade ICANS (p=0.84), grade ≥3 ICANS (p=0.36), duration of CRS (p=0.18) or ICANS (p=0.64), or IEC-HS (p=0.16) across the four dose categories. Time to onset of CRS was shorter for the standard-high dose compared to the low dose (6 days vs. 8 days; p=0.08). Importantly, there was no significant difference in the rate of DNT (3.0%, 9.2%, 8.8%, 5.4%; p=0.24). Similarly, there was no significant difference in overall response rates (97%, 96%, 96%, 88%; p=0.50) or complete response rates (75%, 65%, 75%, 66%; p=0.10) by dose. The median follow-up was 12.3 months (IQR: 6.9, 20.5). For patients who received a standard-low dose (0.5, 0.6), the median PFS was 17.5 (IQR: 13.5, NR) months. For the standard dose range of (0.6, 0.8), the median PFS was 28.7 (95% CI: 19.8, NR) months, while the median PFS for the standard-high dose (0.8, 1.0) was not reached. For the low dose range of <0.5, the median follow up was only 8.7 months, which did not allow reliable estimation of the median PFS. While the overall difference in PFS among the groups did not reach statistical significance by the log rank test, there was a clear trend toward improved PFS with higher cell doses in the multivariable model, with outcomes clearly ordered in the same direction as the cell dose categories. A similar trend was also evident in the rates of 12-month PFS which showed an improvement with increasing dose (62% ,67%, 73%, 80%). Conclusions: In this large, real-world cohort of RRMM patients treated with cilta-cel, a lower cell dose was not associated with reduced incidence or severity of CRS, ICANS, DNT, or IEC-HS. Conversely, a dose-response correlation with PFS was observed, with higher doses trending toward longer median and 12-month PFS. It remains unknown if a lower cell dose in the commercial setting reflects poor T cell quality, yet these findings suggest that dose reduction of cilta-cel may not be an effective strategy to mitigate toxicities and might be associated with a trend toward lower efficacy. Therefore, the standard target dose should be utilized to maximize patient outcomes and further prospective dose exploration is warranted.

Abstract Introduction: Elranatamab, a BCMA-CD3 bispecific antibody, has shown efficacy in relapsed multiple myeloma (MM), but real-world data on its safety and effectiveness are limited. Methods: We conducted a retrospective, multi-center study of patients (pts) treated with commercial elranatamab from 8/2023–3/2025 at 9 U.S. academic centers. Logistic and Cox regression were used for binary and time-to-event outcomes, respectively. Multivariable analysis (MVA) adjusted for prior lines of therapy (LOTs), baseline Hgb (per g/dL), and LDH (per 100 U/L) as continuous variables; and for BCMA exposure, extramedullary disease (EMD; extraosseous soft tissue lesions), and ECOG ≥2 as binary variables. Results: Of 130 pts, median age was 71 yrs (range 39–95); 57% were female, 82% white, 13% black, and 35% had ECOG ≥2 (11% ≥3). Median LOTs was 6; 91% were triple-class refractory, 49% penta-refractory, 49% BCMA-exposed (median 15.5 mo [IQR 11.8–20.5] since last exposure), and 49% had prior anti-BCMA CAR-T. Most recent BCMA exposures included: CAR-T (84%), TCE (9.4%), and ADC (6.3%). Only 22% met MagnetisMM-3 cohort A eligibility (which excluded BCMA-exposed pts). High-risk cytogenetics (del(17p), t(4;14), t(14;16), or amp(1q)) were present in 44% (25%, 13%, 6.3%, and 7.9%, respectively). EMD was seen in 22%. Median treatment duration was 4.0 mo (95% CI 2.93–6.3) overall and 7.9 mo (95% CI 5.83–NA) with ≥VGPR. Discontinuation due to toxicity or non-relapse mortality occurred in 12% but was significantly lower among those receiving IVIg (5% vs. 17%, p=0.031); IVIg was given in 47%. The overall response rate (ORR) was 65%, including ≥VGPR in 46% and ≥CR in 36%, consistent with MagnetisMM-3 (ORR 61%, ≥CR 35%; Lesokhin et al. Nat Med. 2023). After median follow-up of 7.5 mo, median PFS was 4.3 mo (95% CI 3.4–11.3), OS was 14.6 mo (95% CI 8.6–NA), and DOR was 12.2 mo (95% CI 6.1–NA). In contrast, MagnetisMM-3 (Prince et al., ASH 2024) reported median PFS and OS of 17.2 and 24.6 mo, respectively, with DOR not reached despite 28.4 mo of follow-up. In univariate analysis, ECOG ≥2 was associated with lower ORR (45% vs. 71%; OR 0.34, 95% CI 0.16–0.73, p=0.006), shorter OS (4.3 mo vs. NA; HR 2.41, 95% CI 1.33–4.35, p=0.004), and shorter PFS (1.7 vs. 6.5 mo; HR 1.77, 95% CI 1.09–2.87, p=0.020). Prior BCMA-directed therapy was linked to reduced odds of ≥VGPR (OR 0.38, 95% CI 0.19–0.77, p=0.008) and ≥CR (OR 0.43, 95% CI 0.20–0.89, p=0.025). Higher baseline LDH was linked to shorter OS (HR 1.37, 95% CI 1.23–1.53, p<0.001) and PFS (HR 1.31, 95% CI 1.18–1.44, p<0.001). Higher baseline Hgb was associated with higher ORR (OR 1.46, 95% CI 1.20–1.81, p<0.001) and ≥CR (OR 1.54, 95% CI 1.26–1.92, p<0.001). Among BCMA-exposed pts, recent exposure (<1 [n=15] vs. ≥1 yr [n=32]) was associated with shorter OS (4.1 mo vs. NA; HR 3.66, 95% CI 1.26–10.6, p=0.017). In MVA, higher baseline LDH remained independently associated with shorter OS (aHR 1.36, 95% CI 1.19–1.54, p<0.001) and PFS (aHR 1.27, 95% CI 1.13–1.43, p<0.001); higher Hgb with greater odds of ≥CR (aOR 1.44, 95% CI 1.14–1.85, p=0.003) and longer PFS (aHR 0.84, 95% CI 0.72–0.99, p=0.034); and BCMA exposure with lower odds of ≥CR (aOR 0.32, 95% CI 0.10–0.91, p=0.037). CRS occurred in 40% (grade ≥2 in 12.3%, grade 3 in 2.3%), and ICANS in 17% (grade ≥2 in 7.7%). These rates contrast with MagnetisMM-3 (no grade ≥3 CRS, 3.4% ICANS). ICANS risk was lower in BCMA-exposed pts (9.4% vs. 24%; OR 0.32, 95% CI 0.11–0.85, p=0.029), and decreased with more LOTs (OR 0.73, 95% CI 0.55–0.92, p=0.016) and higher Hgb (OR 0.71, 95% CI 0.52–0.94, p=0.023). Tocilizumab and steroids were used in 36% (treatment 28%, prophylaxis 9.2%) and 23%, respectively. Steroid use was less common in BCMA-exposed pts (11% vs. 34%; OR 0.23, 95% CI 0.08–0.60, p=0.004) and declined with more LOTs (OR 0.68, 95% CI 0.52–0.85, p=0.002). Infections occurred in 40% of the cohort, more common in pts with CrCl <40 mL/min (59% vs. 36%; HR 2.58, 95% CI 1.02–6.80, p=0.049). IVIg was linked to improved infection-free survival (HR 0.59, 95% CI 0.37–0.93, p=0.023). Conclusions: Elranatamab demonstrated meaningful activity in real-world relapsed MM, though PFS and OS were shorter than in MagnetisMM-3, likely reflecting an older, frailer population with higher disease burden. ICANS was more frequent than in MagnetisMM-3. Baseline anemia and elevated LDH, markers of poor marrow reserve and higher disease burden, were strongly linked to worse outcomes.

Abstract Background: IEC-HS is a potentially life-threatening complication following CAR-T therapy in RRMM. Reliable diagnostic biomarkers are needed to help expeditiously identify cases to initiate prompt treatment and supportive care. Serum ferritin, a routinely available laboratory parameter, is commonly elevated in IEC-HS and has been used to identify cases. However, ferritin can also be elevated in cytokine release syndrome (CRS) or secondary to baseline tumor-related inflammation. The optimal diagnostic threshold for post-CAR-T ferritin in IEC-HS in RRMM has not been previously established. Methods: This study used data from 15 centers within the US Multiple Myeloma Immunotherapy Consortium to identify the optimal post-CAR-T ferritin threshold to distinguish RRMM patients (pts) with and without a diagnosis of IEC-HS. Receiver operating characteristic (ROC) analysis was used to determine the optimal threshold based on Youden's Index. The performance of the threshold was evaluated overall and stratified by CAR-T product (cilta-cel, ide-cel). Additional analyses included the temporal relationship of peak ferritin and IEC-HS diagnosis, the evaluation of IEC-HS criteria according to ferritin levels, comparison of IEC-HS criteria co-occurrence, and comprehensive baseline characteristic comparisons across ferritin strata. Results: Of 1502 RRMM CAR-T recipients (ide-cel, n=712; cilta-cel, n=790), 74 patients (4.9%) had a provider-determined diagnosis of IEC-HS. A post-CAR-T ferritin threshold of 7470 ng/mL was identified as optimal for distinguishing pts with and without IEC-HS (AUC 0.938). Sensitivity (0.904) and specificity (0.934) were both very high, indicating high discriminatory ability. Stratified ROC analyses showed near-identical optimal thresholds for cilta-cel (7450 ng/mL; sensitivity 0.885, specificity 0.936, AUC 0.94) and ide-cel (7470 ng/mL; sensitivity 0.952, specificity 0.933, AUC 0.95), indicating minimal impact of CAR-T product on ferritin's prognostic utility. Baseline pt characteristics (N=1,413) differed significantly by ferritin threshold. Pts above the ferritin threshold of 7470 (N=154) were younger (median 64 vs 67 years; p=0.004), more frequently male (65% vs 56%; p=0.043), had higher baseline ferritin (1,300 vs 187; p<0.001), higher ECOG at apheresis (p=0.001), more likely penta-refractory (p=0.016), had higher baseline bone marrow plasma cell burden (p<0.001), and had higher R-ISS scores (p<0.001). Evaluation of IEC-HS criteria (Hines et al, TCT 2023) demonstrated significantly higher rates of laboratory and clinical criteria, including hepatic transaminase elevation (43% vs 15%), hypofibrinogenemia (53% vs 0%), cytopenias (95% vs 81%), hypertriglyceridemia (43% vs 8%), ICANS (52% vs 23%), renal insufficiency (20% vs 0%), and soluble IL-2 receptor elevations (47% vs 4%), in pts with ferritin >7500 ng/mL compared to those with lower ferritin. Heatmap visualization revealed distinct patterns of co-occurring criteria in high- and low-ferritin groups. Assessment of the timing of peak ferritin and IEC-HS diagnosis among IEC-HS cases revealed a median difference of 0 days (IQR: -1, 0), suggesting simultaneous occurrence. Median time to max ferritin was 9 days (IQR 8,12) in IEC-HS pts compared to 8 days (IQR 5,10) in non-IEC-HS pts (Wilcoxon p<0.05). Conclusions: In this analysis of over 1500 patients, a post-CAR-T ferritin level of 7500 ng/mL robustly identifies RRMM pts with IEC-HS following either cilta-cel or ide-cel. Pts exceeding this threshold demonstrate marked enrichment in IEC-HS diagnostic criteria and significant differences in baseline characteristics, warranting further study of the role of ferritin in IEC-HS diagnosis and early intervention.

Abstract Introduction: IEC-HS is an emerging and potentially life-threatening complication in multiple myeloma (MM) patients (pts) treated with CAR-T therapies. We conducted a retrospective, multi-institutional analysis to define the features and outcomes of IEC-HS after ide-cel or cilta-cel in the real-world setting. Methods: This study used data from 15 centers within the US Multiple Myeloma Immunotherapy Consortium for patients with relapsed/refractory MM (RRMM) who received commercial cilta-cel or ide-cel. IEC-HS was defined by each center based on diagnostic criteria (Hines et al, TCT 2023). Kaplan-Meier and multivariable Cox models were used for time-to-event outcomes while logistic regression was used for categorical outcomes. Results: Of 1502 RRMM pts who received either ide-cel (n=712) or cilta-cel (n=790), 74 patients (4.9%) had a provider-determined diagnosis of IEC-HS. Product-specific incidences were 2.9% for ide-cel and 6.7% for cilta-cel. The median time from CAR-T infusion to IEC-HS onset was 9.5 days (range 2-37 days). IEC-HS-related clinical findings (Hines et al, 2024) included cytopenias (95%), elevated soluble IL-2R levels (79%), fever (76%), elevated LDH (71%, median 1,800 U/L), hypofibrinogenemia (70%), hypertriglyceridemia (65%), ICANS (63%), hepatic transaminase elevation (56%), pulmonary involvement (46%), renal insufficiency (29%), hyperbilirubinemia (22%), and hemophagocytosis in bone marrow (6%). The median interval from peak CRS to IEC-HS onset was 4 days (IQR 1–6). Some variables, such as splenomegaly and coagulopathy, were not systematically collected. Nearly all pts received pharmacologic intervention: corticosteroids (94%, n=59), anakinra (76%, n=48), tocilizumab (71%, n=45), emapalumab (13%, n=8), ruxolitinib (16%, n=10), or etoposide (3%, n=2). Only one pt (2%) did not receive any IEC-HS therapy. Among those evaluable for outcomes, 58% (n=35) improved, 12% (n=7) developed further CAR-T-related complications (e.g., recurrent IEC-HS, delayed neurotoxicity), and 30% (n=18) had no therapeutic response and died. Compared to non-IEC-HS pts (n=1,428), those with IEC-HS were younger (median age 63 vs 66), male (61% vs 57%), and more frequently received cilta-cel (72% vs 52%, all p<0.01). They had higher rates of triple-class (81%) and penta-refractory (43%) disease, greater pre-treatment bone marrow plasma cell burden (40% vs 6%), and higher baseline ferritin (1058 vs 208 ng/mL). Prior autologous SCT was less common, and advanced R-ISS stage was more prevalent. IEC-HS was associated with dramatically worse PFS and OS: with cilta-cel, median PFS was 6.5 months (mo) with IEC-HS (vs 33.1 without); for ide-cel, 8.9 vs 11.4 mo. Median OS for cilta-cel IEC-HS pts was 9.6 mo (not reached in non-IEC-HS pts); for ide-cel IEC-HS, 19.6 mo (vs 40.8 mo). Multivariable analysis confirmed IEC-HS as an independent predictor of shorter PFS (HR 1.88, 95% CI 1.29–2.74, p=0.0011) and OS (HR 2.30, 95% CI 1.39–3.83, p=0.0013). Notably, IEC-HS was not associated with lower response rates – either best CR (63.9% vs 64.0%, p=0.71) or ORR (91.8% vs 90.9%, p=0.97). Cilta-cel pts had a higher probability of achieving a deep (CR) response, regardless of IEC-HS status. Grade > 3 CRS occurred in 14% (n=3/21) of ide-cel and 15% (n=8/52) of cilta-cel IEC-HS pts, versus 2% (n=12/691) and 2% (n=13/737) in non-IEC-HS pts, respectively. Any-grade ICANS was observed in 67% (n=14/21) of ide-cel and 55% (n=29/52) of cilta-cel IEC-HS cases, compared to 26% (n=179/690) and 20% (n=148/738) in non-IEC-HS. Grade ≥3 ICANS occurred in 29% (n=6/21) of ide-cel and 26% (n=14/52) of cilta-cel IEC-HS cases, relative to 4% (n=25/690) and 4% (n=27/738) in pts without IEC-HS. Severe infections were also more common: 71% (n=15/21) of ide-cel and 53% (n=28/52) of cilta-cel IEC-HS pts experienced at least one infection, compared to 31% (n=214/691) and 29% (n=217/737) in non-IEC-HS groups. Conclusions: IEC-HS is an uncommon but severe and early complication after CAR T-cell therapy for RRMM. Despite similar ORRs with or without IEC-HS, IEC-HS was associated with significantly worse PFS and OS for both ide-cel and cilta-cel. These findings support the need for vigilant monitoring and potential preemptive treatment strategies to better manage this syndrome.

Abstract Introduction: Bispecific T-cell engagers (TCE) targeting BCMA (teclistamab, elranatamab) and GPRC5D (talquetamab) are important therapeutic options in relapsed/refractory MM (RRMM). However, data on the independent prognostic impact of individual cytogenetic abnormalities and functional high-risk MM on outcomes with TCEs remains limited. Methods We included RRMM patients treated with BCMA TCEs (teclistamab, elranatamab) and talquetamab across 15 centers in the US. Patients where TCEs were used only as bridging therapy to CAR-T were excluded. High-risk cytogenetic abnormalities (HRCA) included del(17p), t(4;14), t(14;16), 1q gain/amplification (1q21+), del(1p) before initiation of TCE. Functional high-risk disease (FHRMM) was defined as PFS <18 months with frontline therapy. Extramedullary disease (EMD) included visceral or soft tissue disease and excluded paraskeletal disease. Progression-free survival (PFS) was estimated from TCE initiation using the Kaplan–Meier method and compared using the log-rank test. Univariate and multivariable Cox proportional hazards models were used to identify predictors of PFS in the entire cohort and the subcohorts of BCMA TCEs and talquetamab (Talq). Results We analyzed 943 treatment initiations with TCEs in RRMM, comprising 577 BCMA-directed TCEs [teclistamab (n=436) and elranatamab (n=141)] and 366 talquetamab initiations. The median follow-up from TCE initiation was 13.4 months (95% CI: 12.5–14.2) and median age was 68 years (interquartile range 61-75 years). Two ore more HRCAs were noted in 30% of the cohort (34% in Talq vs. 28% in BCMA TCEs, p=0.04), EMD was present in 21% of patients (26% in Talq vs. 18% in BCMA TCEs, p=0.002), and 45.5% of patients had FHRMM (47% in Talq vs. 45% in BCMA TCE, p=0.54). The median prior lines of therapy was 6 (interquartile range: 5-8), with 92% being triple-class refractory (TCR); 60% received prior BCMA-directed therapy (85% in Talq vs. 45% in BCMA TCE, p<0.0001) and 45% had prior CAR-T in 45% (57% in Talq vs. 37% in BCMA TCE, p<0.001). The best overall response rate (ORR) was 67.1 % for the entire cohort (66.4% for BCMA cohort and 68.2% for Talq), with 32.5% patients achieving a ≥ complete response. The median PFS was 7.7 months (95% CI: 6.7–8.6) for the entire cohort, with a median PFS of 10.1 months (95% CI: 7.5-13.4) for teclistamab and 10.1 months (95% CI: 3.9-NR) for elranatamab. In the more heavily pretreated talq cohort, the median PFS was 6.4 months (95% CI: 5.1-7.5). In a univariate analysis (UVA), several HRCAs were associated with inferior PFS−del(17p) (HR 1.59), t(4;14) (HR 1.43), del(1p) (HR 1.54), and ≥2 HRCAs (HR 1.64), all p<0.01. Apart from HRCAs, adverse disease characteristics included FHRMM (HR 1.20) and EMD (HR 1.46); all p<0.05. Among laboratory markers, hemoglobin <9 g/dL (HR 2.10), platelet count <75 ×10⁹/L (HR 1.96), and elevated ferritin (≥600 ng/mL; HR 2.17) (all p<0.01) were prognostic for PFS. ECOG ≥2 (HR 1.62), prior BCMA-directed therapy (HR 1.56), and prior CAR-T (HR 1.44) (all p<0.001) were also associated with inferior PFS. In a multivariable analysis (MVA), prior BCMA therapy (HR 1.72, p<0.0001), ferritin >600 ng/mL (HR 1.68, p<0.0001), hemoglobin <9 g/dL (HR 1.53, p=0.001), ECOG PS ≥2 (HR 1.52, p=0.0009), del(17p) (HR 1.44, p=0.0034) and FHRMM (HR 1.26, p=0.047), were associated with inferior PFS. Within the talq cohort (n=366), EMD (HR 1.64), del(17p) (HR 1.42), del(1p) (HR 1.54), FHRMM (HR 1.34), ECOG ≥2 (HR 1.56), ferritin >600 (HR 1.88), hemoglobin <9 g/dL (HR 1.6), platelet count <75 ×10⁹/L (HR 1.36) and leukopenia <0.25 x 10⁹/L (HR 1.52) were adverse prognostic markers on UVA. A MVA confirmed the independent impact of ferritin >600 ng/mL (HR: 1.77), ECOG ≥2 (HR 1.61) and functional high-risk status (HR 1.52) on PFS, whereas del(17p) and EMD were trending toward significance. Within the BCMA TCE cohort (n=577), prior BCMA therapy (HR 1.9), ferritin >600 (HR 1.79), ECOG ≥2 (HR 1.55), Hb <9 g/dL (HR 1.54), and del(17p) (HR 1.52) were independently associated with inferior PFS on a MVA.Conclusions: In this large real-world cohort of TCE, outcomes varied by fitness, disease biology, and treatment history. The ECOG PS, elevated ferritin, functional high-risk status and del(17p) were consistently associated with inferior PFS. Prior BCMA exposure was an independent risk factor for inferior PFS in the BCMA TCE cohort, but not with talquetamab.

Abstract Introduction: Ciltacabtagene autoleucel (cilta-cel) has shown high efficacy in relapsed MM, but further efforts are needed to mitigate non-ICANS delayed neurotoxicity (DNT) and non-relapse mortality (NRM). Identifying risk factors associated with DNT and NRM may help with risk mitigation by aiding the development of interventions for potentially modifiable risk factors and also help with clinical decision making. Methods: In this multi-center retrospective study from the US MM Immunotherapy Consortium, we evaluated 761 patients treated at 15 centers receiving standard of care cilta-cel for relapsed MM between May 2022 to December 2024. Risk factors for DNT, particularly Parkinsonism and NRM were evaluated in by univariable and multivariable analysis. Any NRM events occurring after disease progression were censored for NRM evaluation. Results: The median age of the cohort was 65 years old (range: 30-88), median prior lines of therapy (pLoT) were 5 (range: 1-23). Cilta-cel was used in earlier relapse (1-3 pLOT) in 16% (n=120) patients. High-risk cytogenetics [del 17p, t(14;16) or t(4;14)] were present in 39%, with extramedullary disease (EMD) in 27% and R-ISS stage III in 18% of patients, respectively. Majority of patients (86%) received bridging therapy with response to bridging (≥ partial response, PR) seen in 33% of patients, respectively. Median follow up was 10.1 months, with response rate of 92% and CR rate of 70%. DNT was seen in 10% (n=75) of patients, with distribution as follows: Parkinsonism in 2.9% (n=22), cranial nerve palsy in 4.6% (n=35) and other DNT in 2.4% (n=18), with some patients manifesting more than one type of DNT. Risk of DNT was higher in patients who did not respond to bridging therapy (Any DNT: 12% vs 6%; Parkinsonism: 5% vs 0.5%, both p<0.05) Of the 22 cases of Parkinsonism, 21 patients (95%) did not respond to bridging, even though they achieved a post CAR-T response with ORR of 91% and ≥ CR in 68%. Absolute lymphocyte count (ALC), a surrogate measure of CAR expansion was higher in patients who developed DNT, particularly Parkinsonism, including ALC at days 7,14,21,28 and as peak ALC in the first month post cilta-cel (p<0.05 for all). Median peak ALC for patients with vs without Parkinsonism was: 5.88 vs 1.17/uL (p<0.001). We evaluated risk of Parkinsonism with various thresholds of peak ALC expansion. Amongst patients who developed Parkinsonism vs. not, peak ALC was as follows, > 1000/uL: 100% vs 57%, > 2500/uL: 73% vs 19% and > 3000/uL: 68% vs 14% (all p<0.001). The absolute risk of Parkinsonism with ALC > 3000 vs ≤ 3000/uL was 12% vs 1%, p<0.001; for ALC 2500 vs ≤ 2500uL was 9% vs 1%, p<0.001. On multivariable analysis, peak ALC > 3000/uL (OR: 12.7, p<0.001) and non-response to bridging therapy (OR: 9.9, p=0.03) were independent risk factors for developing Parkinsonism after cilta-cel. After cilta-cel, 1 and 2 year NRM estimates were 9% and 10%, respectively. Amongst 63 (8%) patients experiencing NRM events, the most common cause of NRM was infectious complications (35, 56%), followed by acute immune-mediated adverse events (AEs) like CRS, ICANS, IEC-HS in 14 (22%), delayed immune mediated AEs like DNT and colitis in 6 (9.5%), second cancers in 5 (8%) and other causes in 3 (5%) patients, respectively. When evaluating the timing of NRM events, the risk of infection related mortality remained relatively stable in the first year, though immune mediated toxicty deaths were uncommon after 6 months, while SPMs were uncommon within the first 6 months. On multivariable analysis, non-response to bridging (HR 2.41, p=0.046), poor performance status ≥ 2, high-risk cytogenetics and age ≥ 70 years were independent predictors for NRM. Conclusion: In a large cohort of over 750 patients receiving cilta-cel, we identified potentially modifiable risk factors for Parkinsonism and NRM. Non-response to bridging therapy and peak ALC > 3000/uL were independent predictors of developing Parkinsonism. Peak ALC of > 2500/uL and > 3000/uL were associated with 9% and 12% absolute risk of Parkinsonism. This indicates that peak ALC of 2500/uL or 3000/uL in the first month after cilta-cel may be a potential biomarker to identify patients for pre-emptive interventions such as steroids that can suppress rapid CAR expansion and perhaps decrease the risk of Parkinsonism. In addition, we need to focus on effective bridging strategies to further decrease the risk of Parkinsonism, as well as NRM with cilta-cel.

Abstract Introduction Ciltacabtagene autoleucel (cilta-cel) has demonstrated unprecedented response rates and progression-free survival (PFS) in relapsed/refractory multiple myeloma (RRMM), but a proportion of patients experience early relapse. Identifying these patients is essential to guide future therapeutic strategies, such as enhanced bridging therapy or consolidation, while avoiding overtreatment in those likely to achieve durable disease control. Methods We conducted a multi-center study of patients treated with cilta-cel at 15 U.S. academic centers. Outcomes were evaluated based on high-risk (HR) features, including functional HR disease (FHR; relapse within 18 months of first-line therapy initiation), true extramedullary disease (EMD), traditional HR cytogenetics as defined in CARTITUDE-1 [deletion 17p, t(4;14), t(14;16)], and a 2024 IMS-IMWG-adapted HR definition (deletion 17p; t(4;14) or t(14;16) with gain 1q or deletion 1p; and gain 1q with deletion 1p). Multivariable Cox regression was used to examine the association of HR features (FHR, adapted IMS-IMWG HR, and EMD, individually and collectively) with PFS while adjusting for baseline ferritin, prior BCMA, and ECOG performance status (PS ≥2). Among patients with ≥18 months of follow-up, we evaluated predictors of early relapse (≤18 months post infusion) using logistic regression. Results Our cohort included 598 patients treated with cilta-cel between 5/2022 and 12/2024 who had available data on all HR features. The median age was 65 years (range 33-83), and the median prior lines of therapy (pLOT) was 5 (range: 1-18, 84% with >3 pLOT); 8% had received prior BCMA-directed therapy, and 27% were penta-refractory. Most patients (88%) received bridging therapy and 30% achieved ≥ partial response. In our cohort, 33% (n=195) had FHR, 43% (n=258) had traditional HR cytogenetics, 42% (n=253) had adapted IMS-IMWG HR disease, and 11% (n=64) had EMD. Median follow up was 10.6 months (range 0.4-34.1). Overall response rate (ORR) and complete response (CR) rates were lower in patients with vs without HR features: FHR (ORR: 89% vs 94%, CR: 61% vs 75%), traditional HR (ORR: 90% vs 94%, CR: 65% vs 74%), adapted IMS-IMWG HR (ORR: 91% vs 94%, CR: 64% vs 75%) and EMD (ORR: 77% vs 94%, CR: 61% vs 71%). Corresponding 12-month PFS was also lower in patients with vs without HR features: FHR (55% vs 79%), traditional HR (63% vs 78%), adapted IMS-IMWG HR (61% vs 80%) and EMD (59% vs 73%). ORR, CR rate, and 12-month PFS in patients without any HR features compared to those with ≥1 HR feature were 96% vs 90%, 81% vs 64%, and 83% vs 65%, respectively. In multivariable models, each HR feature (FHR, adapted IMS-IMWG HR, and EMD) was independently associated with inferior PFS after adjusting for baseline ferritin, prior BCMA, and ECOG PS ≥ 2. However, because early relapse cannot always be identified a priori based on traditional risk factors, we sought to identify predictors of relapse within 18 months of cilta-cel in a subset of patients with ≥18 months of follow-up (N=247; infused by 12/2023). Notably, while FHR (OR=3.04, 95% CI=1.59-5.89) and adapted IMS-IMWG HR (OR=2.07, 95% CI=1.10-3.89) were independently associated with odds of relapse within 18 months, EMD was not (OR=0.90, 95% CI=0.32, 2.40) when accounting for prior BCMA, ECOG PS ≥ 2, and baseline ferritin. We also used a time-varying Cox model to examine each HR feature associated with PFS at two time periods, <18 and ≥18 months, while adjusting for baseline ferritin, ECOG PS, and prior BCMA. We confirmed that FHR and adapted IMS-IMWG HR were both associated with relapse <18 months (HR=2.05, 95% CI=1.48-2.83 and HR=1.56, 95% CI=1.11-2.19) but not in the ≥18-month time period (HR=0.70, 95% CI=0.19-2.59 and HR=0.76, 95% CI=0.24-2.40). The magnitude of the association for EMD with PFS was similar across both time periods (<18 months HR=1.67, 95% CI=1.09-2.57 and ≥18 months HR=2.17, 95% CI=0.45-10.40). Conclusion While cilta-cel leads to high response rates and durable PFS in RRMM, a subset of patients with FHR and adapted IMS-IMWG HR remains at increased risk for early relapse. In this large multi-center cohort, we describe PFS outcomes across high-risk subgroups and identify key predictors of relapse within 18 months of cilta-cel. These findings inform risk-adapted therapeutic strategies and interventional trials, including bridging, consolidation, or maintenance approaches, to improve outcomes in the highest-risk RRMM patients.

Abstract Introduction: The CAR-T therapies ide-cel and cilta-cel are approved for patients (pts) with relapsed/refractory multiple myeloma (RRMM). The aim of this study was to determine the incidence, subtypes, and associated risk factors for subsequent primary malignancies (SPMs) in MM pts treated with CAR-T therapy in the real-world setting. Methods: A retrospective, multicenter observational cohort study was conducted of pts who received CAR-T therapy between May 2021 and Dec 2024 at 15 centers within the US Multiple Myeloma Immunotherapy Consortium. Logistic models were used for univariable analyses of invasive SPMs (excluding non-melanoma skin cancers). Variables significant at p < 0.10 were included as candidate variables in the multivariable analysis. Time to event endpoints were analyzed using Kaplan-Meier curves. Results: Of n=1460 CAR-T recipients, median follow-up from the time of CAR-T infusion for the entire cohort, ide-cel, and cilta-cel pts was 13.1, 16.9, and 10 months, respectively. A total of 55 invasive SPMs were noted in 53 pts (SPM incidence 3.6%). The incidence rate of SPMs was 4.55 per 1,000 person-years, based on 53 SPMs occurring over 11,646.14 person-years (calculated from CAR-T to the SPM diagnosis, death, or last follow-up). Baseline characteristics were similar for pts with no SPM versus SPM including: age at CAR-T (median 67 vs 65), female (36% vs 43%), Black (13% vs 16%), prior autologous transplant (87% vs 80%), lenalidomide for ≥2 years (31% vs 27%), high risk cytogenetics (23% vs 29%), and known clonal hematopoiesis (7.5% vs 9.9%). Differences were observed in baseline characteristics among pts with SPM versus no SPM for ≥2 prior alkylator lines of therapy (LOT) (82% vs 60%, p=0.002) and median prior LOT (6 vs 5, p=0.008). There was a trend for more patients with SPMs being age ≥70 (35% vs 37%, p=0.074). Of the 53 SPMs, 26 (49%) were myeloid (MDS or AML), 19 (35.8%) were solid, 7 (13.2%) were of T-cell origin, and 1 was a B-cell lymphoma. Of the T-cell SPMs, three were of T-LGL, though one of the T-LGL pts later developed an invasive CNS T-cell lymphoma (CAR-negative). There were four cases of confirmed CAR-positive T-cell SPMs (all pts treated with cilta-cel), of which two were indolent T-cell lymphoma of the GI tract and two were cutaneous PTCL. There was no difference in total incidence of SPMs among pts who received ide-cel (total=4.4%; myeloid=2.2%, T-cell=0.04%) versus cilta-cel (total=3%; myeloid=1.4%; T-cell=0.5%) (p=0.21). Median OS from the time of CAR-T therapy was 40.8 months for pts without SPM compared to 27.6 months for pts with SPM (p=0.4). Median OS did not differ by myeloid, solid, and T-cell subgroup: 26.4, 37.2, and 24 months, respectively (p=0.21). Median time from CAR-T cell to SPM was 12 months overall, and by subtypes of myeloid, solid, and T-cell was 13.2, 9.6, and 9.6 months, respectively (p=0.74). There was no difference in time to any SPM among pts receiving ide-cel versus cilta-cel (p=0.61). An earlier time to diagnosis of myeloid SPM was observed for cilta-cel versus ide-cel (4.8 vs 20.4 months; p=0.003). Median OS from the time of diagnosis of any SPM, myeloid, solid, or T-cell SPM was 9.6, 7.2, 15.6, and not reached in months, respectively (p=0.006), demonstrating that pts diagnosed with myeloid subtype SPM had inferior OS from the time of their SPM diagnosis compared to other subtypes. The cause of death of 4/11 myeloid SPM pts was the myeloid SPM itself. In univariable analysis for the entire cohort, age ≥70 (p=0.079), ≥5 prior LOT (p=0.012), and ≥2 prior alkylator LOT (p<0.001) were associated with higher risk for SPM. In multivariable analysis, ≥2 LOT containing alkylators was associated with higher risk of SPM (p=0.005). For the univariable analysis of the myeloid subgroup, ≥2 prior alkylator LOT (p=0.016) and ≥2 years of lenalidomide maintenance (p=0.063) were associated with higher risk of SPM. In multivariable analysis, ≥2 years of lenalidomide (p=0.065) was associated with a trend toward increased risk of myeloid SPM. Conclusions: With a median follow up of 13.1 months, the incidence of developing a SPM following CAR-T in pts with RRMM was 3.6%, of which approximately half were myeloid malignancies. There was no difference in SPM incidence when comparing the two CAR-T products. Pts treated with ≥2 alkylator LOT had a higher risk of SPM in multivariable analysis and may warrant additional monitoring for SPM development.