Pérez, Waleska S.

Abstract Introduction: Axi-cel, an autologous anti-CD19 CAR T-cell therapy has shown high and durable response rates and a manageable safety profile among R/R FL pts in the ZUMA-5 trial (Jacobson et al. 2022; Neelapu et al. 2024). Evidence from real-world data showed favorable early outcomes in a broader population using CIBMTR data, with comparable outcomes by ZUMA-5 eligibility, age, lines of therapy (LOT), and prior bendamustine (benda) use (Jacobson et al. 2023). This study investigated long-term outcomes and the association between age, performance status, comorbidities, and therapies given prior to infusion among R/R FL pts treated with axi-cel. Methods: Pts with R/R FL who received commercial axi-cel between 03/2021–10/2023 in the US were identified from the CIBMTR® registry; pts without consent, with prior non-transplant cellular therapy, and FL grade 3B or 3A/3B unspecified or unknown were excluded. Descriptive analyses were done among all pts and by age at infusion (<65 vs ≥65 y), Karnofsky performance score (KPS), presence of hepatic, cardiovascular (CV), or moderate to severe pulmonary comorbidities, prior treatments (benda pre-leukapheresis, autologous hematopoietic stem cell transplant [autoHSCT]), and lymphodepletion (LD) therapy. Multivariable (MV) Cox and logistic regression were used to adjust for confounders. Results: In total, 238 pts from 68 centers were included (data cut-off October 2024). Median age at infusion was 61 yr (range, 29-83; ≥65 yr, 38%), and 79% were non-Hispanic White. KPS of pts was ≤70% (11%), 80% (35%), or 90-100% (54%); 2% had ECOG ≥2. Most (75%) had ≥1 clinically significant comorbidity (hepatic, 6%; CV, 15%; pulmonary, 18%). Median (min, max) prior LOT was 4 (1,13); 74% received benda pre-leukapheresis, and 6% had benda LD therapy. At a median follow-up of 24.1 months, objective response rate (ORR) was 96% (complete response [CR] rate, 91%). The 2-yr (95% CI) DOR, PFS, and OS were 70% (63-77), 64% (57-71), and 84% (78-89) respectively. Grade ≥3 cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) occurred in 4% and 18% of pts (any grade, 74% and 42%), respectively. Prolonged cytopenias by day 30 occurred in 14% of pts (neutropenia [10%] and thrombocytopenia [8%]) while 29% had clinically significant infections at 6 months. Second primary malignancies occurred in 16 pts (7%), with 7 (2%) being therapy-related myeloid neoplasm. The leading primary causes of death (n=34) were relapse/progression (10; 29%), organ failure (7; 21%), and infection 5 (15%). Cumulative incidence of non-relapse mortality at 2-yr was 9%. Outcomes were generally comparable among age, autoHSCT, and comorbidity subgroups. However, effectiveness outcomes differed by prior benda use (Yes vs No): ORR (95% vs 98%); CR (88% vs 98%); DOR (65% vs 89%), PFS (58% vs 84%), and OS (82% vs 91%) at 2 years. By LD therapy (single agent benda vs cyclophosphamide + fludarabine [Cy + Flu]): the ORR was 93% vs 96%; CR rate was 57% vs 93%. On MV analysis, prior benda use was associated with (OR/HR [95% CI]): worse CR (0.02 [<0.01-0.43]), DOR (3.69 [1.51-9.02], and PFS (2.21 [1.12-4.38]). Pts given benda LD therapy had (OR/HR [95% CI]): worse CR rate (0.02 [<0.01-0.16]), DOR (7.59 [2.33-24.72]), and PFS (4.89 [1.79-13.39]) compared to those who received Cy + Flu. CRS and ICANS were lower among those with prior benda use (Yes vs No): any-grade CRS (70% vs 87%); Grade ≥3 CRS (3% vs 8%); any-grade ICANS (36% vs 61%); and grade ≥3 ICANS (17% vs 25%). By LD therapy (single agent benda vs Cy + Flu): the Grade ≥3 CRS and ≥3 ICANS were 0% vs 5% and 7% vs 19% respectively. Any-grade ICANS was higher among those aged ≥ 65 yr vs <65 yr (53% vs 35%). On MV analysis, pts who had prior benda use were less likely to have any-grade CRS (0.30 [0.12-0.75]), and any-grade ICANS (0.23 [0.11-0.50]. Pts ≥ 65 yr had higher any-grade ICANS (2.31 [1.18 – 4.50]). Summary/Conclusion: This long-term follow up of axi-cel in R/R FL shows durable responses and manageable safety similar to ZUMA-5. Outcomes among the elderly and those with comorbidities were generally comparable to the overall R/R FL population. Although benda use pre-leukapheresis was associated with less durable responses, we were unable to determine whether this association is limited to use close to axi-cel infusion, as data on timing of use was unavailable. The associations for benda LD should be interpreted with caution given the small sample size.

7023 Background: Axi-cel is an autologous chimeric antigen receptor (CAR) T-cell therapy approved for adults with R/R LBCL after ≥ 1 prior line of therapy (LoT). Adverse events, such as cytokine release syndrome (CRS) and neurologic events (NEs), may deter centers from using axi-cel in an outpatient (OPT) setting, though individual centers have observed comparable safety and effectiveness in OPT and inpatient (IPT) care (Furqan et al. Blood Adv . 2024). Here, we present safety and effectiveness outcomes of axi-cel by intention to treat in OPT and IPT settings in a multicenter real-world dataset. Methods: Pts receiving axi-cel for R/R LBCL in the US from 01/2021-07/2023 with data in the Center for International Blood and Marrow Transplant Research (CIBMTR) registry were eligible for analysis. Pts with prior allogeneic transplant or unknown intended care setting were excluded. Of potential pts, 119 OPT pts were identified from 29 centers where an increasing trend was seen (9.6% of pts in 2021 were OPT, 13.5% in 2022, 22.8% in 2023). Pts were matched to 119 IPT pts by propensity score matching on age, sex, comorbidities, lactate dehydrogenase (LDH), bulky disease, prior LoT, chemosensitivity, and infusion year (see table). Results: OPT pts had median age of 63 y (25% ≥ 70), 66% were male, and 67% had ≥ 1 comorbidity. Half (50%) had elevated LDH and 73% had 1 prior LoT. Bulky disease was reported in 3%, and 60% had chemo-resistant disease. Outcomes were analyzed at median follow-up of 12 mo. Safety and effectiveness outcomes were similar between OPT and IPT pts (see table). In multivariate analyses, no differences were found between intended care setting and CRS (odds ratio [OR] 1.09 [95% CI 0.51-2.35]), CRS Gr ≥ 3 (OR 0.57 [0.12-2.60]), NEs (OR 1.14 [0.65-2.00]), or NEs Gr ≥ 3 (OR 0.98 [0.48-2.00]). Among OPT pts, 24% and 50% did not require hospital admission within 30 d and 3 d, respectively. In pts aged ≥ 70 y, only any Gr NEs were higher in the OPT group. Conclusions: After matching on key factors that may be used to select pts for OPT infusion, outcomes were comparable between intended care settings. These findings corroborate prior results and support the consideration of axi-cel in appropriate OPT care settings. Outcomes between matched pts with R/R LBCL receiving axi-cel intended for OPT or IPT. OPT (n=119) a IPT (n=119) a CRS any Gr / Gr ≥ 3 83 (75−89) / 3 (<1−7) 83 (74−89) / 4 (1−10) NE any Gr / Gr ≥ 3 47 (38−57) / 19 (12−27) 46 (37−56) / 21 (14−30) Overall / complete response rates 78 (69−85) / 68 (59−76) 76 (67−83) / 62 (52-70) Duration of response @ 12 mo 64 (52−74) 69 (58−78) Progression-free survival @ 12 mo 53 (43−62) 53 (43−61) Overall survival @ 12 mo 71 (61−78) 72 (62−79) Non-relapse mortality @ 12 mo 6 (2−11) 4 (1−8) Hospital admission within 30 days of infusion / median duration (range), d 76 (67−83) / 9 (2−53) Not Applicable a Percent (95% CI) unless otherwise specified.

Abstract Background: Obesity is increasing in prevalence worldwide and has potential implications on chemotherapy dosing and selection of patients for therapy. Auto HCT improves outcomes for patients with MM, but optimal chemotherapy dosing for obese patients is poorly defined. Methods: We identified 1087 patients reported to the CIBMTR between 1995 and 2003 who underwent auto HCT for MM as part of initial therapy, defined as within 18 months of diagnosis, and received high-dose melphalan conditioning, with or without total body irradiation (TBI). We categorized patients by body mass index (BMI) as normal (18.5– 24.9), overweight (25–29.9), obese (30–34.9), or severely obese (≥35). Underweight patients (BMI <18.5, N=9) were excluded from analysis. We analyzed overall survival (OS) and progression-free survival (PFS) from date of transplant, using Kaplan-Meier curves and the log-rank test for univariate analyses and using Cox proportional hazards models for multivariate analyses. Results: Cases were reported from 114 centers in 10 countries. There were 292 patients of normal weight (27%); 472 were overweight (43%), 198 were obese (18%), and 125 severely obese (11%). Median follow-up of survivors was 63, 61, 60 and 59 months, respectively. Significant baseline differences among BMI groups indicate that obese patients selected for transplant were younger (median age 58, 58, 56, and 55 years, respectively, p=0.005) and had less severe disease at diagnosis, with lower bone marrow plasmacytosis and less frequent renal failure, hypercalcemia, and severe anemia. Obese patients received higher total melphalan doses but lower doses per square meter of body surface area (calculated based on actual body weight). Univariate analyses show no significant effect of BMI category on either OS or PFS. However, among patients who received TBI as part of conditioning, multivariable analyses show a significant effect of BMI on PFS (p-value for interaction 0.006). In this subgroup, a higher BMI was associated with longer PFS (p=0.006, Figure 1). Among patients who received melphalan alone, no effect of BMI was apparent (Figure 2). The difference in PFS for patients receiving melphalan/TBI was due to a decreased risk of relapse among obese patients. Pairwise comparisons of conditioning regimen (TBI vs. no TBI) within BMI categories showed significant reduction in risk of treatment failure for obese (HR=0.54, p=0.04) and severely obese (HR=0.32, p=0.001) patients who received TBI. No differences in OS were apparent in multivariate analyses. Relative risks (RR) for PFS from a multivariable model adjusting for possible confounders are shown below: TBI No TBI n RR (95% CI) P n RR (95% CI) P Normal 44 1.00 Poverall=0.006 248 1.00 Poverall=0.18 Overweight 62 0.92 (0.60–1.40) 0.69 405 0.90 (0.75–1.08) 0.24 Obese 21 0.49 (0.27–0.90) 0.021 177 0.85 (0.68–1.07) 0.16 Severely obese 22 0.39 (0.20–0.76) 0.005 100 1.12 (0.86–1.45) 0.42 Conclusion: Obesity, when measured by BMI, has no statistically significant effect on OS among patients with myeloma receiving high-dose melphalan. Among patients receiving melphalan with TBI, a higher BMI is associated with improved PFS. The reason for the restriction of this effect to TBI-containing conditioning regimens requires further investigation. The current common strategy of reducing melphalan doses (i.e. calculating based on ideal or adjusted body weight) does not appear to impair outcomes for obese patients. Obesity should not exclude patients from consideration of autologous transplantation. Figure Figure

Abstract Multiple Myeloma (MM) is the most common indication for autologous hematopoietic stem cell transplantation (auto HCT). However, little information is available regarding the outcome of patients (pts) with the rarer immunoglobulin subtypes IgD and IgM, which represent 2% and 0.5%, respectively, of all MM cases. In addition, IgD MM has been reported previously to have a poorer prognosis, at least after conventional therapy. The CIBMTR conducted a retrospective analysis of MM pts transplanted between 1995–2005 to describe the characteristics and results of auto HCT in IgD (n=36) and IgM (n=11) among 3578 MM patients with auto HCT during this period. Median follow-up of survivors was 41 (range 2–130) months for pts with IgD and 58 (range 5–101) months for those with IgM MM. Among pts with IgD subtype, median age was 52 years (yrs), 67% were male, 36% had a creatinine >2 mg/L, 61% had Durie-Salmon stage III disease at diagnosis and 33% had Kappa Serum Light chain; the corresponding values for IgM pts were 58 yrs, 36%, 73% and 55% respectively. Prior to auto HCT, 75% of IgD pts were chemosensitive and 25% had received >2 lines of chemotherapy, while all IgM pts were chemosensitive and none had received more than 2 lines of prior therapy. Median time from diagnosis to auto HCT was 9 months in both subtypes. The most common conditioning regimen was singleagent melphalan, and all but 1 pt with IgD disease were grafted with blood stem cells. The small sample size precluded multivariate analysis for potential prognostic factors for outcome. Below table summarizes the post-auto HCT results in these pts contrasted with a reference pool of IgG and IgA MM receiving auto HCT in the same time period. Outcomes, probability (95% CI) IgD IgM IgG/IgA (n=36) (n=11) (n=1475) 100-day mortality, % 0 9 ( 0 – 32) 7 (5 – 8) Non MM deaths, % @ 1 yr 0 9 (0 – 32) 5 (4 – 7) @ 3 yrs 3 (0 – 13) 21 (2 – 51) 16 (14 – 18) Relapse/ Progression, % @ 1 yr 21 (9 – 37) 20 (2 – 49) 18 (16 – 20) @ 3 yrs 59 (41 – 76) 32 (8 – 64) 36 (34 – 39) Progression-free survival, % @ 1 yr 79 (63 – 91) 71 (41 – 93) 77 (74 – 79) @ 3 yrs 38 (21 – 56) 47 (17 – 78) 47 (44 – 50) Overall survival, % @ 1 yr 87 (74 – 97) 91 (68 – 100) 79 (77 – 85) @ 3 yrs 69 (51 – 84) 68 (36 – 93) 53 (50 – 57) No striking differences are apparent in the post auto HCT outcomes of patients with IgD and IgM MM. These results are also consistent with published outcomes of pts with IgD/ IgM MM (Wechaleker et al Ann Hematol. 2005 Feb; 84(2):115–7; Maisner et al Bone Marrow Transplant. 2008 Jan; 41(1):51–4).

Abstract Abstract 680 Cytogenetics play an essential role in determining the prognosis of patients with AML. However, there is still no validated cytogenetics grouping scheme that specifically applies to patients undergoing allogeneic stem cell transplantation, which hampers accurate prognostication and risk stratification. We studied 821 adult patients (median age 41, range 18–74) who underwent SCT between 1999 and 2004 for AML (excluding APL) in CR1 or CR2 and who were reported to the CIBMTR from centers with >20 patients meeting study criteria. 75% of patients received a myeloablative conditioning. 496 patients had a normal karyotype. The primary cytogenetics reports were manually reviewed for 92% of the patients with an abnormal karyotype. We compared the ability of the 6 existing grouping schemes (MRC, CALGB, EORTC/GIMEMA, SWOG/ECOG, DFCI, and Monosomal Karyotype (MK) classifications) to stratify patients, using both the Akaike Information Criterion in multivariable models and the C-statistic. Among all existing schemes, the DFCI system provided a marginally superior stratification for overall and leukemia-free survival. We also built a new classification using individual cytogenetic abnormalities in a Cox model that included other significant covariates (performance status, therapy-related disease, conditioning intensity, graft source, donor match, duration of CR1, and gender match). This CIBMTR scheme (see Table), which is similar to the DFCI scheme except for the inclusion of patients with t(8;21) in the intermediate group, could stratify patients into 3 groups with similar treatment-related mortality but significantly different overall survival, leukemia-free survival, and incidence of relapse. This scheme appeared to apply to both patients in CR1 and in CR2 (see FiguresF2). This transplant-specific scheme could be adopted for prognostication purposes and to stratify patients with karyotypic abnormalities entering transplantation clinical trials. Future studies may clarify the relative outcome of patients with t(8;21) and refine this scheme with the inclusion of molecular abnormalities. Disclosures: No relevant conflicts of interest to declare.

Abstract Therapy-related myelodysplastic syndromes (t-MDSs) and acute myeloid leukemia (t-AML) have a poor prognosis with conventional therapy. Encouraging results are reported after allogeneic transplantation. We analyzed outcomes in 868 persons with t-AML (n = 545) or t-MDS (n = 323) receiving allogeneic transplants from 1990 to 2004. A myeloablative regimen was used for conditioning in 77%. Treatment-related mortality (TRM) and relapse were 41% (95% confidence interval [CI], 38-44) and 27% (24-30) at 1 year and 48% (44-51) and 31% (28-34) at 5 years, respectively. Disease-free (DFS) and overall survival (OS) were 32% (95% CI, 29-36) and 37% (34-41) at 1 year and 21% (18-24) and 22% (19-26) at 5 years, respectively. In multivariate analysis, 4 risk factors had adverse impacts on DFS and OS: (1) age older than 35 years; (2) poor-risk cytogenetics; (3) t-AML not in remission or advanced t-MDS; and (4) donor other than an HLA-identical sibling or a partially or well-matched unrelated donor. Five-year survival for subjects with none, 1, 2, 3, or 4 of these risk factors was 50% (95% CI, 38-61), 26% (20-31), 21% (16-26), 10% (5-15), and 4% (0-16), respectively (P < .001). These data permit a more precise prediction of outcome and identify subjects most likely to benefit from allogeneic transplantation.

We compared the treatment-related mortality, relapse rate, disease-free survival (DFS), and overall survival (OS) by cytogenetic risk group of 261 patients with acute myeloid leukemia in first complete remission (CR1) and 299 patients in CR2 in undergoing matched unrelated donor hematopoietic stem cell transplantation (HSCT). For patients in first CR, the DFS and OS at 5 years were similar for the favorable, intermediate, and unfavorable risk groups at 29% (95% confidence interval [CI], 8%-56%) and 30% (22%-38%); 27% (19%-39%) and 29% (8%-56%); and 30% (95% CI, 22%-38%) and 30% (95% CI, 20%-41%), respectively. For patients in second CR, the DFS and OS at 5 years were 42% (95% CI, 33%-52%) and 35% (95% CI, 28%-43%); 38% (95% CI, 23%-54%) and 45% (95% CI, 35%-55%); and 37% (95% CI, 30%-45%) and 36% (95% CI, 21%-53%), respectively. Cytogenetics had little influence on the overall outcome for patients in first CR. In second CR, outcome was modestly, but not significantly, better for patients with favorable cytogenetics. The graft-versus-leukemia effect appeared effective, even in patients with unfavorable cytogenetics. However, treatment-related mortality was high. Matched unrelated donor HSCT should be considered for all patients with unfavorable cytogenetics who lack a suitable HLA-matched sibling donor.