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Abstract Background: Gastrointestinal (GI) symptoms are frequent in patients (pts) with systemic light chain amyloidosis (AL), yet their clinical significance remains poorly defined. We investigated the role of symptomatic GI involvement in disease burden, survival, and organ-specific outcomes in a large single-center cohort. Methods From 2010–2025, 4,396 AL pts were evaluated at our center; 560 pts (13%) had provider-attributed symptomatic GI AL. Pts with localized AL or positive biopsy without GI symptoms were excluded (n=38). We analyzed relationships between GI symptoms, anatomic/histologic involvement, laboratory parameters, survival, and need for nutritional support using Wilcoxon rank-sum, Chi-square, Kaplan-Meier, and logistic regression tests. Results GI symptoms included early satiety (n=320/57%), diarrhea (n=189/34%), nausea (n=184/33%), abdominal pain (n=148/26%), dysphagia (n=119/21%), vomiting (n=75/13%), GI bleeding (n=74/13%), and heartburn (n=71/13%). Only nausea and GI bleeding were not associated with cardiac (n=366/65%) renal (n=274/49%) or hepatic (n=84/15%) AL, whereas dysphagia, early satiety and heartburn were more frequent with cardiac (all OR=1.7), abdominal pain and diarrhea with hepatic (OR=2 and 1.6, respectively), and vomiting with renal involvement (OR=2; all p<0.04). Autonomic involvement impacted GI symptoms, often without proof of parenchymal GI amyloid. Of the 124 pts with formal autonomic testing, only 44 (35%) had positive GI biopsies as compared to AL GI pts without proven autonomic involvement (240/436, 55%). Pts with autonomic involvement were more symptomatic than pts with positive GI biopsies, suffering more often from dysphagia (29% vs 19%), diarrhea (41% vs 32%), and gastroparesis (34% vs 9%, all p<0.001). We screened changes in body weight, calcium, VitB12, Hb, PO4, and albumin at diagnosis. Of the 175 pts with documented weight loss in this cohort, pts with GI AL lost more weight compared to those with other organ involvement (21% vs 14% of weight, p=0.002), and had lower phosphate (3.7 vs 4.0 mg/dL, p=0.06). In our cohort of pts with GI symptoms, 298 (53%) had a positive GI biopsy. Biopsy-proven anatomic involvement dictated symptoms (all p<0.05): Of the 20 pts with positive esophageal biopsy, dysphagia was present in 45%; only 33% of the pts without an esophageal biopsy had dysphagia. Similar patterns were seen for the 170 pts with a positive gastric biopsy (n=170) in terms of heartburn (21% vs 11%), for the 165 pts with positive small bowel biopsies in terms of abdominal pain (68% vs 32%), and for the 130 pts with positive colon biopsies and diarrhea (46% vs 33%). Specific histopathological patterns were prognostic. Mucosal involvement (n=161) was an independent risk factor for survival compared to submucosal (n=64) and vascular (n=102) involvement throughout the GI tract (HR 1.83; p=0.03). Three-layer GI infiltration was associated with inferior mOS (2.4 vs 5.1 vs 7.8 y for 3 vs 2 vs 1-layer involvement, HR 3.19/1.56/1; p<0.05). Counterintuitively, vascular involvement had the lowest risk of bleeding in all GI anatomic sites (p=0.02). In the colon, only mucosal involvement was associated with a higher risk of bleeding (OR=5; p=0.04). GI involvement in AL pts did not worsen prognosis (mOS 10.0/6.3y, p=0.02), and pts with isolated GI AL (n=74/13%) had an even better survival (55% surviving at 10 y). Cachexia (n=120; mOS 3.5 vs 7.8 y, p<0.001), need for nutritional support (n=36; mOS 0.9 vs 7.0 y, p<0.001), and diarrhea (mOS 5.8 vs 6.9 y, p=0.06) were risk factors for death. In pts with hematologic response (≥PR), bleeding did not recur within 3 y (n=27), but even with response, diarrhea (n=160) persisted in 39%. Resolution was less frequent without hematologic response (persistence in 69%, OR=3.5). Improvement was most often due to treatment of bacterial overgrowth (11/35 pts; 68%) and loperamide (54/59 pts; 91%). Conclusion In AL, meaningful GI involvement is defined by nausea, diarrhea, occurrence of bleeding, and malnutrition. These are primarily associated with mucosal infiltration. GI symptoms can occur in the face of autonomic involvement. While long-term persistence of GI bleeding is rare after serologic response, cachexia and persistent diarrhea drive morbidity, need for nutritional support, and poor survival.

Abstract Accurate prediction of risk of progression from smoldering (SMM) to active multiple myeloma (MM) is paramount to individualized early therapeutic strategies with minimum risk of overtreatment. Current risk stratification models do not account for evolving biomarker trajectories. We assembled the largest cohort to date of 2,270 SMM patients from six international centers with longitudinal clinical and biological data to train and validate the PANGEA 2.0 risk models. Four evolving biomarkers were significantly associated with shorter time-to-progression: M-protein increase ≥0.2g/dL, involved:uninvolved serum free light chain ratio increase ≥20, creatinine increase >25%, and hemoglobin decrease ≥1.5g/dL. PANGEA 2.0 outperforms established models including the 20/2/20 and IMWG models by more accurately predicting progression (C-statistics=0.69–0.84), even without biomarker history (C-statistics=0.69–0.83) or recent bone marrow biopsy. PANGEA 2.0 is an easy-to-use, open-access tool (https://ghobrial.shinyapps.io/pangea_2_calculator) to improve and individualize SMM risk stratification. Validation tools are available to compare PANGEA 2.0 to established models (https://ghobrial.shinyapps.io/pangea_validation).

Background Emerging evidence has demonstrated rare subacute to late neurological toxicities (NTs) after BCMA CAR T-cell therapy (CAR-T) in multiple myeloma (MM). These adverse events can be categorized as: 1) Parkinsonism (PD), 2) cranial nerve (CN) palsies, and 3) peripheral neuropathies/Guillan Barré syndrome (GBS). These toxicities can cause significant morbidity, but given their relative rarity in clinical trials, there is limited data regarding evaluation and treatment. To our knowledge, this is the largest and only global registry of delayed NTs after BCMA CAR-T. Methods We retrospectively established a registry of NTs via the Immune Therapy Working Committee of the International Myeloma Working Group (IMWG). We gathered data pertaining to demographics, MM characteristics, MM response, NT signs/symptoms, diagnostic workup, and treatment. Result A total of 52 patients with delayed neurotoxicity were included from 14 institutions and 6 countries; 92% received ciltacel, 4% idecel, and 4% investigational CAR-T. Median age at CAR-T infusion was 65 years; 69% were male and 88% were Caucasian. Median bone marrow plasma cell (PC) burden was 15% prior to CAR-T (range 0-95%). Patients received a median of 4 prior lines of therapy (LOT), with 67% progressing on last LOT. Seventeen percent had pre-existing neurological diagnoses (including stroke, epilepsy, migraines). We identified sixteen cases of PD (94% with movement disorder, 69% with cognitive impairment, 75% with personality changes), occurring at a median of 26 days (range: 15-87) after CAR-T. Ninety four percent had CRS (grade (G)1 50%, G2 38%, G3 6%, G4 0%), while 19% had ICANS (G1 13%, G2 6%, G3-G4 0%). Median peak absolute lymphocyte count (ALC) was 9.5 x 109/L, peak C-reactive protein (CRP) 60.9 mg/L, and peak ferritin 1893.5 ug/L within the first 30 days. Concurrently, 3 upper respiratory infections (URIs) and 2 low-level HHV7 in the cerebrospinal fluid (CSF) were detected. A median of 73% of T-cells in the CSF were CAR-T, based on a flow cytometry assay. Ten patients received steroids (median 19 days after symptoms, 70% partial response, 20% no response, 10% unknown), 2 received intrathecal (IT) methotrexate-based therapy (median 32 days after symptoms, 1 with no response, 1 unknown), 5 received intravenous (IV) cyclophosphamide (median 31 days after symptoms, 40% full response, 20% partial response, 40% no response), 4 received high-dose IVIG ≥1g/kg for one or more dose (50% partial response, 50% no response), and 6 received dopamine agonists. There were 37 CN palsies (76% CN7, 15% CN6, 7% CN5, 2% CN3), occurring at a median of 37.5 days (range: 7-482) after CAR-T. Eighty one percent had CRS (G1 68%, G2 14%, G3-G4 0%); 11% had G1 ICANS (G2-G4 0%). Median peak ALC was 4.1 x 109/L, CRP 25.4 mg/L, and ferritin 543 ug/L within the first 30 days. We identified 2 concurrent URIs, 4 CMV viremia (50% with viral load >1500 IU/mL), 1 HHV6 viremia, and 1 HSV in the CSF. Thirty-two (86%) received steroids for a median duration of 12 days, 50% with full response, 3% with no response, and 47% with partial response (of which 43% had later full recovery without further intervention). One received IT methotrexate and another received IV cyclophosphamide without response. Thirteen (41%) received IVIG, of which 38% was high-dose IVIG. Four patients with CN palsies developed peripheral neuropathy/GBS. Eight patients (15%) in this cohort were not heavily pre-treated (≤1 prior LOT); 7 developed CN palsies (6 after ciltacel, 1 after investigational CAR-T) and 1 PD (after idecel). These patients had median <5% PC; none had extramedullary disease. Median ALC was 4.14 x 109/L, CRP 33 mg/L, and ferritin 448.5 ug/L within the first 30 days. Conclusions Delayed NT requires prompt recognition, evaluation for alternative causes, and treatment. In our cohort, the majority of patients were male and Caucasian, suggesting that sex and race may impact the likelihood of developing NT. Individuals with PDs had greater inflammatory response (CRS, ALC, CRP, ferritin) compared to those with CN palsies. CN palsies responded to steroids and/or IVIG, whereas PD had at best partial response to steroids, prompting additional therapy. These toxicities notably did occur in less heavily pre-treated patients, perhaps driven by immune fitness and greater circulating T-cells rather than MM burden. At the time of the annual meeting, data will be updated with additional NTs from less heavily pre-treated patients.

Background:Patients (pts) with multiple myeloma (MM) often receive immunomodulatory drugs (IMiDs; eg, lenalidomide), proteasome inhibitors (eg, bortezomib), and anti-CD38 monoclonal antibodies (mAbs) as part of their initial treatment. However, most pts relapse following initial treatment, with increasing attrition rates observed at each subsequent line of therapy (LOT), creating an unmet need for treatment options for pts with relapsed/refractory MM (RRMM) who have prior exposure to these agents. Current regimens for pts who have prior exposure to lenalidomide and anti-CD38 mAbs include elotuzumab, pomalidomide, and dexamethasone (EPd; approved in Europe and the US) and pomalidomide, bortezomib, and dexamethasone (PVd; approved in Europe and Australia), but disease control, as well as depth and durability of response, could be improved. Talquetamab (tal) and teclistamab (tec), targeting CD3 and either G protein-coupled receptor family C group 5 member D (GPRC5D, tal) or B-cell maturation antigen (tec), are the first T-cell redirecting bispecific antibodies (BsAbs) approved as monotherapies in Europe and the US for the treatment of pts with triple-class exposed (TCE) RRMM. Use of these novel immunotherapies in earlier LOTs, either with a dual-antigen targeting approach or by enhancing the activity of the BsAb with an IMiD (pomalidomide), may provide deeper, more durable responses and improve pt quality of life. Preliminary data using these combination treatments have shown promising results: in the phase 1b MonumenTAL-2 study (NCT05050097), tal+pomalidomide (tal-P) demonstrated overall response rates (ORRs) of >84% in pts with RRMM with ≥2 prior LOTs and in the phase 1b/2 RedirecTT-1 study (NCT04586426), tal+tec (tal-tec) showed ORRs of >77% in pts with TCE RRMM. MonumenTAL-6 (NCT06208150) is a randomized, open-label, multicenter, phase 3 study comparing the efficacy of tal-P vs investigator's choice of EPd or PVd and tal-tec vs investigator's choice of EPd or PVd in pts with RRMM with 1-4 prior LOTs, including lenalidomide and an anti-CD38 mAb. Study Design and Methods: Eligibility includes pts aged ≥18 years with documented MM per International Myeloma Working Group (IMWG) criteria, with measurable disease at screening, an Eastern Cooperative Oncology Group performance status of 0-2, who have received 1-4 prior LOTs (including lenalidomide and an anti-CD38 mAb in any prior LOT), and have progressive disease on or after their last therapy. Pts with prior exposure to pomalidomide, tec, or GPRC5D-directed therapies are excluded. Approximately 795 pts are randomized 1:1:1 to receive tal-P, tal-tec, or investigator's choice of EPd or PVd. Tal is administered subcutaneously at 0.8 mg/kg every other week (Q2W), and tec is administered subcutaneously at 3.0 mg/kg every 4 weeks (Q4W) following step-up doses of each. Pts are permitted to switch from Q2W to Q4W tal dosing following a confirmed very good partial response or better (≥VGPR) at cycle 5. Pomalidomide, EPd, and PVd are administered per approved dosing schedules. Randomization is stratified by number of prior LOTs (1 vs ≥2), International Staging System stage at screening (I vs II/III), and investigator's choice of treatment (EPd vs PVd). Pts receive study treatment until disease progression, start of subsequent anti-MM treatment, death, intolerable toxicity, withdrawal of consent, or end of study, whichever occurs first. A finite dosing approach is employed for tal and tec. The primary endpoint is progression-free survival (PFS). Secondary endpoints include ORR assessed per IMWG 2016 criteria, ≥VGPR rate, complete response (CR) or better rate, rate of minimal residual disease-negative CR, overall survival, PFS on next LOT, time-to-next treatment, and pt-reported outcomes. This study is actively recruiting, with more than 160 locations in 26 countries. Results will provide insights into the efficacy of the combination of BsAbs in therapeutic strategies that exploit their different mechanisms of action to overcome treatment resistance and improve outcomes of pts with TCE RRMM in earlier LOTs.

Introduction: Patients with TCE RRMM have a high disease burden and often report worsening HRQoL with additional lines of therapy. The single-arm, phase 2 KarMMa study demonstrated that ide-cel, a B-cell maturation antigen (BCMA)-directed chimeric antigen receptor T cell therapy, improved HRQoL from baseline in patients with TCE RRMM who had received ≥ 3 prior regimens (Delforge M, et al. Blood Adv 2022;6:1309-1318). Furthermore, in the phase 3 KarMMa-3 clinical trial (NCT03651128), ide-cel significantly improved progression-free survival and response compared with standard regimens in patients with TCE RRMM who had received 2-4 prior regimens (Rodriguez-Otero P, et al. N Engl J Med 2023;388:1002-1014). Here we assessed the comparative effects of ide-cel versus standard regimens on HRQoL in patients with TCE RRMM who had received 3-4 prior regimens including an immunomodulatory agent, a proteasome inhibitor, and daratumumab (an anti-CD38 monoclonal antibody) using data from the KarMMa-3 study. Methods: Patient-reported outcomes (PROs) were assessed by the European Organization for Research and Treatment of Cancer (EORTC) Quality-of-Life Questionnaire-Core 30 (QLQ-C30), EORTC Quality of Life Questionnaire Multiple Myeloma Module (QLQ-MY20), and EQ-5D-5L. The pre-specified primary domains of interest included EORTC QLQ-C30 global health status/QoL, physical functioning, cognitive functioning, fatigue, and pain; EORTC QLQ-MY20 disease symptoms and side effects of treatment; and the EQ-5D-5L visual analog scale (EQ-5D VAS). PROs were collected at screening (baseline), the day of ide-cel infusion (ide-cel) or first treatment dose (standard regimens), monthly from 2 to 28 months, and thereafter every 3 months. Comparisons were performed on least squares (LS) mean changes from baseline through 28 months between arms using constrained longitudinal data analysis (cLDA). Effect size was estimated by Hedges' g. The comparative effects of ide-cel versus standard regimens on time to confirmed improvement and time to confirmed deterioration (defined by prespecified change thresholds) were assessed via stratified Cox proportional hazards regression analyses. All P values are nominal and not adjusted for multiple testing. Statistical significance was set at P < 0.05. Results: Baseline characteristics were well balanced among the patients in the ide-cel arm (n = 167) and the standard regimen arm (n = 93), with a median age of 63 years and a median time of 4.7 years from RRMM diagnosis to study screening. Completion rates of HRQoL assessments were high over time for most visits (> 75%). At baseline, mean HRQoL domain scores were similar between arms. Overall LS mean changes from baseline to 28 months showed significant differences in favor of ide-cel versus standard regimens (nominal P < 0.05) for 11 domains (effect sizes of 0.26-0.82), and 7 (4 primary: global health status/QoL, cognitive functioning, pain, EQ-5D VAS; 3 secondary: dyspnea, insomnia, constipation) of them exceeded the prespecified MID thresholds (Table). Time to confirmed improvement was significantly shorter (nominal P < 0.05) in the ide-cel arm than in the standard regimen arm for 10 domains, including all primary domains except pain. Time to confirmed deterioration was longer in the ide-cel arm than the standard regimen arm for most domains, with significant differences in emotional functioning, cognitive functioning, and dyspnea (EORTC QLQ-C30). Finally, side effects of treatment favored the ide-cel versus standard regimen arm (EORTC QLQ-MY20) (Table). Conclusions: These patient-reported findings demonstrate that compared with standard regimens, treatment with ide-cel improved MM-relevant disease symptoms, functioning, and overall health status/HRQoL of patients with TCE RRMM in the KarMMa-3 trial. These data further substantiate the superior treatment outcomes of ide-cel over standard regimens in this patient population. Overall, treatment with ide-cel may help alleviate detriments to HRQoL in these patients with complex disease.

Background: An interim analysis (data cutoff date April 18, 2022) of the international, open-label, phase 3 KarMMa-3 trial (NCT03651128) showed the chimeric antigen receptor T cell therapy idecabtagene vicleucel (ide-cel) significantly improved progression-free survival and treatment response rates, as well as HRQoL, as compared with standard regimens, in patients with triple-class exposed (TCE) RRMM who had received 2-4 prior regimens (Rodriguez-Otero P, et al. N Engl J Med 2023;388:1002-1014; Delforge M, et al., HemaSphere, 2023;7(S3):P905). The aim of the present study was to analyze the effect of ide-cel versus standard regimens (daratumumab [DARA], pomalidomide, and dexamethasone [DEX]; DARA, bortezomib, and DEX; ixazomib, lenalidomide, and DEX; carfilzomib and DEX; or elotuzumab, pomalidomide, and DEX) on HRQoL in KarMMa-3 trial participants with an extended follow-up of patient-reported outcomes (PRO) data collection (data cutoff date April 28, 2023). Methods: In KarMMa-3, HRQoL was assessed using the European Organisation for Research and Treatment of Cancer (EORTC) Quality-of-Life Questionnaire-Core 30 (QLQ-C30), EORTC Quality of Life Questionnaire Multiple Myeloma Module (QLQ-MY20), and EQ-5D-5L. HRQoL assessments were completed at screening (baseline); the day of ide-cel infusion or the first dose of standard treatment; and monthly from 2 to 28 months; and every 3 months thereafter. The prespecified primary outcomes of interest were EORTC QLQ-C30 global health status/QoL, physical functioning, cognitive functioning, fatigue, and pain; EORTC QLQ-MY20 disease symptoms and side effects of treatment; and the EQ-5D visual analog scale (EQ-VAS). Least squares (LS) mean changes from baseline through month 25 for ide-cel and standard regimens were compared by constrained longitudinal data analysis (cLDA). Effect sizes were estimated by Hedges' g. The effect of ide-cel versus standard regimens on time to confirmed improvement and deterioration in HRQoL (defined by prespecified change thresholds and sustained duration) were compared by stratified Cox proportional hazards regression. There was no adjustment for multiple testing, and all P values reported are nominal. Results: Overall, 254 patients were randomized to the ide-cel arm and 132 to the standard regimens arm. Baseline characteristics were well balanced across treatment arms; both arms had a median age of 63 years, a median of 3 prior anti-myeloma regimens, and median time from MM diagnosis to screening was 4 years. The baseline HRQoL scores were generally comparable between treatment arms. Overall LS mean changes from baseline to month 25 showed significant differences (nominal P value < 0.05) in favor of ide-cel for 18 out of 21 HRQoL domains, with effect sizes (Hedges' g) of 0.27 to 0.82 (Table). For 13 of these domains (including 6 primary domains of interest), the difference in overall LS mean change from baseline exceeded the prespecified minimum important difference (MID) threshold. Time to confirmed improvement was significantly shorter in the ide-cel arm than the standard regimens arm for 19 domains, including all primary domains of interest (Table). Time to confirmed deterioration showed trends of being longer in the ide-cel arm than the standard regimens arm for most domains and was significantly longer for emotional functioning, cognitive functioning, social functioning, dyspnea, and constipation as measured by the EORTC QLQ-C30. The time to confirmed deterioration in side effects of treatment (based on the EORTC QLQ-MY20) was significantly longer for patients in the ide-cel arm and time to confirmed improvement was significantly faster, as compared with the standard regimens arm (Table). Conclusions: In the KarMMa-3 trial, patients with TCE RRMM who had received 2-4 prior regimens, ide-cel significantly and meaningfully improved MM-relevant symptoms, functioning, and overall health status/HRQoL compared with standard regimens. Confirmed HRQoL improvements in the ide-cel arm occurred sooner than standard regimens. PRO improvements were sustained over more than 2 years, which is notable after a single infusion treatment with ide-cel. These patient-reported findings further support the benefit of ide-cel in this patient population.

Background Chimeric antigen receptor (CAR) modified T-cells are leading to a paradigm shift in the treatment of relapsed/refractory (RR) multiple myeloma (MM). A high proportion of patients treated with CAR T-cells, however, experience prolonged cytopenia, with the mechanism remaining poorly understood. Here, we aimed to explore potential biomarkers that might correlate with cytopenia following CAR T-cell therapy in RRMM. Methods We prospectively collected peripheral blood (PB) of RRMM patients treated with idecabtagen-vicleucel (ide-cel) at the following time points: prior to lymphodepleting chemotherapy (LDC) (baseline), after ide-cel on day 4, 7, 14 and 28, and monthly thereafter. Cytopenia was determined according to the CTCAE version 5.0. Flow cytometry was performed with the following markers: CD45, CD3, CD4, CD8, CD62L, CD45RA, CD19, CD14, CD138, CD38 and a BCMA-CAR-detection marker. Results We included 222 PB samples at different sampling time points from 35 RRMM patients, who were pretreated with a median of 5 therapy lines (range 2-10). All patients were triple-class exposed and, 34 (97%) and 9 (26%) patients underwent autologous and allogeneic stem cell transplant (SCT), respectively. First, we analyzed the relationship between baseline parameters and the duration of grade ≥3 cytopenia after ide-cel (n=35). Notably, patients who received allogeneic SCT or >4 lines of therapy did not develop longer lasting cytopenia than the remaining patients. We found a correlation between the baseline hemoglobin level and the duration of grade ≥3 anemia (r=-0.55, P<0.001). Similarly, low baseline platelet count indicated long duration of grade ≥3 thrombocytopenia (r=-0.48, P=0.003). Moreover, high baseline ferritin level correlated with long duration of grade ≥3 anemia (r=0.52, P<0.001) and thrombocytopenia (r=0.51, P=0.002). Furthermore, the maximum ferritin level after ide-cel was an indicator for long lasting grade ≥3 anemia (r=0.73, P<0.001) and thrombocytopenia (r=0.71, P<0.001). Interestingly, we found significant correlations between the duration of grade ≥3 lymphopenia and baseline CD4+ T-cell frequency (r=0.41, P=0.02), CD8+ T-cell frequency (r=-0.38, P=0.04) and CD4+/CD8+ ratio (r=0.4, P=0.03). Noteworthy, patients with β2-microglobulin level >3.5 mg/l displayed longer duration of grade ≥3 anemia (median: 9 vs 0 day, P=0.007) and neutropenia (median: 43 vs 12 days, P=0.02) compared with the remaining patients, suggesting that high tumor load might be a risk factor for prolonged cytopenia after ide-cel. Second, we divided the follow-up PB samples (n=187) into two groups: early (<d60) and prolonged (≥d60) cytopenia to account for direct toxic effects related to LDC. A high ferritin level was associated with low hemoglobin level (<d60: r=-0.45, P<0.001, ≥d60: r=-0.62, P<0.001) and low platelet count (<d60: r=-0.58, P<0.001, ≥d60: r=-0.81, P<0.001) in both groups. In prolonged cytopenia (≥d60), lymphocyte count correlated with the T-cell count (r=0.7, P<0.001), suggesting that prolonged lymphopenia was mainly attributed to the reduced T-cell count after ide-cel. Of note, the frequency of naïve CD4+ T-cells (CD3+CD4+CD62L+CD45RA+) positively correlated with neutrophil count (r=0.58, P<0.001), hemoglobin level (r=0.37, P=0.03) and white blood cell count (r=0.5, P=0.002) in the ≥d60 group, suggesting that delayed immune reconstruction with reduced naïve CD4+ T-cells might contribute to prolonged cytopenia after ide-cel. Moreover, in the ≥d60 group, lymphocyte count was related with the frequency of CAR+CD4+ (r=-0.58, P<0.001), CAR+CD8+ (r=0.58, P<0.001), CAR-CD4+ (r=-0.72, P<0.001), CAR-CD8+ (r=0.75, P<0.001) T-cells, as well as the ratios of CAR+CD8+/CAR+CD4+ (r=-0.6, P<0.001) and CAR-CD8+/CAR-CD4+ (r=-0.75, P<0.001). Conclusion Here, we present one of the first prospective studies investigating the factors associated with prolonged cytopenia after CAR T-cell therapy in RRMM. High tumor load, preexisting cytopenia and high ferritin level are related with prolonged cytopenia after ide-cel. Delayed immune reconstruction, characterized by reduced naïve CD4+ T-cell count, indicates prolonged cytopenia following ide-cel therapy. Patients with high CD4+/CD8+ ratio are at risk of prolonged lymphopenia (with reduced T-cell count), which may be a risk factor for infectious complications and an issue for subsequent T-cell based immunotherapies.

Introduction: BCMA-directed CAR-T and Bispecific T-cell engager (BiTE) therapies have shown remarkable overall response rates in heavily pretreated patients with relapsed/refractory multiple myeloma (RRMM). This has led to the approval of idecabtagene vicleucel, ciltacabtagene autoleucel and teclistamab by the FDA, EMA and other regulatory agencies. We performed a global survey on accessibility, practice patterns, and toxicity management of commercially available CAR-T and BiTE therapies. Methods: An online survey was completed by clinicians attending the International Myeloma Society's Immune Effector Cell Therapies in Multiple Myeloma Workshop, in-person or virtually, made available for 30 days after the meeting held in March 2023, Boston, MA. Results: 87 clinicians from 16 countries completed the survey, most practicing in an academic practice (86%) and in an urban environment (89%). Sixty-four percent of the respondents practice in North America followed by Europe (25.3%) including Germany, United Kingdom, Ireland, Italy, Netherlands, Spain, France, Greece, and Cyprus, and 6.9% from Asia and 3.4% from Australia. Seventy-seven percent reported CAR-T cell therapy was approved in their country with 44.8% treating 1-5 patients and 14.9% treating >5 patients per month; 67% reported BiTE therapy was approved in their country with 14.9% treating >5 patients per month. Of evaluable responses (n = 40), 62% administered CAR-T therapy inpatient and 15% administered CAR-T therapy outpatient ≥ 50% of the time. Length of time between decision to treat with CAR-T therapy to infusion was 6-12 weeks for 42% of responders and <6 weeks for only 20%. Most (75%) reported inpatient administration of BiTE therapy step-up dosing; 17.5% reported outpatient step-up dosing administered ≥ 50% of the time. Use of institutional or practice SOPs for CAR-T and BiTE therapy patient selection was reported by 85% and 58%, respectively, with the factors influencing SOP outlined in Table 1. Of available CAR-T therapies, 53% prefer cilta-cel and 23% reported CAR-T therapy preference depended most on patients' co-morbidities/frailty (89%), timing of next available apheresis (67%), age (56%), CNS disease (44%) and other factors. Maintenance therapy after CAR-T therapy was reportedly used by 25% and 5% of respondents in 1-10% and 11-50% of their patients, respectively, to “maintain level of response achieved” (50%) or “achieve a deeper level of response” (25%). About half (43%) of the respondents reported using an SOP or particular criteria for secondary Hemophagocytic Lympho-Histiocytosis/Macrophage Activation Syndrome/CAR-related-HLH (sHLH/MAS/CarHLH) management that varied between the use of ASTCT Working Group IEC associated HLH-like syndrome Criteria (47%) (Hines 2023), CARTOX HLH Criteria (24%) (Neelapu 2017) and HLH-2004 criteria (6%). Tocilizumab was used as cytokine release syndrome (CRS) prophylaxis only by one responder. Keppra neurologic prophylaxis was used by 47.5% and 15% of responders for CAR-T and BiTE therapy, respectively. Delayed neurotoxicity with CAR-T was reported in 1-5% of patients by 57.5% of responders and 6-10% of patients by 15% of responders; most common manifestations were other movement/neuromuscular disorder (62%), nerve palsy (55%), and Parkinsonism (45%). Infectious prophylaxis was used to protect against HSV (92.5%), PJP (90%), bacterial pathogens (55%), fungal pathogens (60%), and IVIG (77.5%). However, criteria for infectious prophylaxis use varies widely incorporating IgG levels, infectious history, CD4+ count, B-cell aplasia and cytopenias (48.1 - 88.9%). Most respondents (46.3 - 86.5%) reported completing an infectious work-up including CMV, EBV, Hep B/C, and HIV ( Table 2). Conclusions: Trends of CAR-T and BiTE therapy use and patterns of concurrent prophylactic and supportive care in MM vary widely among academic centers across the globe, demonstrating a need for further understanding of toxicity pathogenesis, toxicity management and consistent guidelines. This survey also demonstrates the great unmet need for access beyond urban centers among the international myeloma community. Prospective studies and claims data analysis should be utilized to evaluate the longitudinal cost of care, quality of life, duration of response and management of infectious disease, neurological or related complications of CAR-T and bispecific TCE therapies.