Cytokine Release Syndrome Events Research Articles

Abstract CT243: Primary analysis of the Phase 2 ELM-2 study: Odronextamab in patients (pts) with relapsed/refractory follicular lymphoma (R/R FL)

Abstract Background: R/R FL is an incurable disease and outcomes worsen with successive relapses. A high unmet need remains for therapies that improve tumor control and extend survival after relapse. Odronextamab, an off-the-shelf CD20×CD3 bispecific antibody, demonstrated compelling efficacy, generally manageable safety, and maintenance of pt-reported overall quality of life scores from baseline in an interim analysis of the ELM-2 study (NCT03888105) in heavily pretreated pts with R/R FL (Villasboas et al. ASH 2023). Here, for the first time, we present the primary analysis of R/R FL in ELM-2. Methods: IV odronextamab was administered in 21-day cycles (C) until disease progression/unacceptable toxicity. Steroid prophylaxis and step-up dosing (0.7/4/20 mg) were used in C1 to mitigate the risk of cytokine release syndrome (CRS), followed by 80 mg on Days (D) 1, 8, and 15 of C2-4. Maintenance dosing continued at 160 mg Q2W, or Q4W if complete response (CR) was durable for 9 months (mo). Primary endpoint was objective response rate (ORR) per Lugano criteria by independent central review (ICR). Secondary endpoints included CR rate, duration of response (DOR), progression-free survival (PFS), and overall survival (OS). Primary analysis was performed when 128 pts had ≥52 weeks’ follow-up. Results: At data cutoff (Oct 20, 2023), 128 pts with FL Grade (Gr) 1-3a were evaluable for efficacy and safety: median age 61 yrs (range 22-84); FLIPI risk score 3-5 57.8%; POD24 49.2%; median 3 prior lines of therapy (2-13); 71.9% refractory to last treatment (Tx); 74.2% refractory to an anti-CD20 antibody. The median no. of Tx cycles was 19.4 (0.1-95.9); 95.3% and 85.2% of pts completed C1 and C4, respectively.Median efficacy follow-up was 20.1 mo; ORR was 80.5% and CR rate was 73.4% confirmed by ICR. Responses were durable (median DOR 22.6 mo; median DOCR 25.1 mo). Median PFS was 20.7 mo and 24-mo PFS was 46.1%. Median OS was not reached and 24-mo OS was 70.1%.The odronextamab safety profile was generally manageable and consistent with previous reports. Tx-emergent adverse events (AEs) occurred in all pts (Gr ≥3 85.9%); 15.6% had AEs leading to Tx discontinuation. With 0.7/4/20 mg step up (n=60), CRS events were mostly low grade (Gr 1 45.0%; Gr 2 10.0%; Gr 3 in 1 pt), occurred mostly in C1, and resolved in a median of 2 days; ICANS was reported in 1 pt (Gr 2). Infection rates were consistent with heavily pretreated, immunosuppressed pts (Leonard et al. JCO 2019; Hayne et al. BBMT 2020), occurring in 79.7% (102/128) of pts (Gr 4/5 14.0%; COVID-19 36.7% [Gr 5 6.3%]).Conclusion: Odronextamab demonstrated deep and durable responses in heavily pretreated pts with R/R FL; 91% of responders achieved CR, correlating with favorable PFS and OS at 24 mo. Odronextamab had a generally manageable safety profile and a low incidence of Gr 3 CRS/ICANS. Odronextamab could offer an important off-the-shelf Tx option for pts with heavily pretreated R/R FL. Citation Format: Geoffrey Chong, Michal Taszner, Silvana Novelli, Seok-Goo Cho, Jose C. Villasboas, Ana Jiménez Ubieto, Benoît Tessoulin, Michelle Poon, David Tucker, Jan Walewski, Yuqin Song, Emmanuel Bachy, Stephanie Guidez, Aranzazu Alonso, Deepa Jagadeesh, Stefano Luminari, Laura Magnano Mayer, Elżbieta Iskierka-Jażdżewska, Monica Tani, Jingxian Cai, Amulya Uppala, Saleem Shariff, Jurriaan Brouwer-Visser, Aafia Chaudhry, Hesham Mohamed, Srikanth Ambati, Tae Min Kim. Primary analysis of the Phase 2 ELM-2 study: Odronextamab in patients (pts) with relapsed/refractory follicular lymphoma (R/R FL) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT243.

Abstract 3616: In vivo expansion patterns of anti-BCMA CAR T-cell in relapsed/refractory multiple myeloma: Comparative immunomonitoring of idecabtagene vicleucel and ciltacabtagene autoleucel

Abstract Introduction: Chimeric antigen receptor (CAR) T cell (CAR-T) treatments have revolutionized the treatment of multiple myeloma (MM). Two CAR-T cell products targeting B cell maturation antigen (BCMA) have received approval for the treatment of MM: idecabtagene vicleucel (idecel) and ciltacabtagene autoleucel (ciltacel). A comparative analysis of in vivo CAR-T responses in patients receiving these novel cellular therapies has not been performed, especially not in the real-world setting. Methods: We prospectively enrolled 23 MM patients treated with idecel or ciltacel in our study GCCC2043. Blood samples were obtained at apheresis, pre-lymphodepleting (LD) chemotherapy, on days 0, +7, +14, +21, +28 and at +3 months post CAR-T. Samples were stained using BCMA or control CAR detection reagents, monoclonal antibodies against T cell surface antigens, and analyzed using flow cytometry. Results: Baseline clinical characteristics, pre-apheresis and pre-LD absolute lymphocyte counts were comparable between groups. There were no G3 cytokine release syndrome (CRS) events whereas G1/2 CRS and all-grade Immune Effector Cell-Associated Neurotoxicity Syndrome (ICANS) events were not significantly different between cohorts. The global overall response rate (ORR) was 78.3% (n=18) and 60.9% (n=14) at days 30 and 90, respectively. At +1 month, 72.7% (8/11) of idecel and 83.3% (10/12) of ciltacel cohort had an objective response (p=0.625). There was no statistical ORR difference between idecel and ciltacel cohorts at 3, 6, and 9 months. Two-way ANOVA of CAR-T expansion studies revealed a trend towards an effect of treatment type (p=0.0595). Time to peak CAR-T numbers was significantly shorter for idecel (p=0.0127), however, ciltacel showed a significantly more pronounced CAR-T expansion (p=0.043) and longer persistence. Peak CAR-T expansion was associated with clinical responses across cohorts at +1 (p=0.034) and +3 months (p=0.050). Day +30 responses were indicative of Day +90 and Day +180 responses (p<0.001, p=0.011). There was no difference in CD8+ CAR T cell peak levels, however, CD4+ CAR T cell peak levels were much higher (p=0.019) for ciltacel vs. idecel. Similarly, there were significantly higher (p=0.002) CD4+/CD8+ double-positive CAR-T peak levels in ciltacel vs. idecel patients. There was no significant difference in the distribution of T cell memory subtypes at peak level. Conclusions: We demonstrate here for the first time significant differences in CAR T cell expansion and persistence patterns following infusion of either idacel or ciltacel. Studies are underway at our institution investigating anti-BCMA CAR T cell responses in more detail and larger numbers of patients. Such studies have the potential to identify predictive/prognostic biomarkers and/or lead to further optimization of myeloma-targeting CAR-T. Citation Format: Mehmet Kocoglu, Aaron P. Rapoport, Etse Gebru, Destiny Omili, Daniel Yamoah, Rediet Mulatu, Jean Yared, Nancy M. Hardy, Michael Kallen, Ashraf Z. Badros, Djordje Atanackovic. In vivo expansion patterns of anti-BCMA CAR T-cell in relapsed/refractory multiple myeloma: Comparative immunomonitoring of idecabtagene vicleucel and ciltacabtagene autoleucel [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3616.

A Phase I Study of Acapatamab, a Half-life Extended, PSMA-Targeting Bispecific T-cell Engager for Metastatic Castration-Resistant Prostate Cancer.

Safety and efficacy of acapatamab, a prostate-specific membrane antigen (PSMA) x CD3 bispecific T-cell engager were evaluated in a first-in-human study in metastatic castration-resistant prostate cancer (mCRPC). Patients with mCRPC refractory to androgen receptor pathway inhibitor therapy and taxane-based chemotherapy received target acapatamab doses ranging from 0.003 to 0.9 mg in dose exploration (seven dose levels) and 0.3 mg (recommended phase II dose) in dose expansion intravenously every 2 weeks. Safety (primary objective), pharmacokinetics, and antitumor activity (secondary objectives) were assessed. In all, 133 patients (dose exploration, n = 77; dose expansion, n = 56) received acapatamab. Cytokine release syndrome (CRS) was the most common treatment-emergent adverse event seen in 97.4% and 98.2% of patients in dose exploration and dose expansion, respectively; grade ≥ 3 was seen in 23.4% and 16.1%, respectively. Most CRS events were seen in treatment cycle 1; incidence and severity decreased at/beyond cycle 2. In dose expansion, confirmed prostate-specific antigen (PSA) responses (PSA50) were seen in 30.4% of patients and radiographic partial responses in 7.4% (Response Evaluation Criteria in Solid Tumors 1.1). Median PSA progression-free survival (PFS) was 3.3 months [95% confidence interval (CI): 3.0-4.9], radiographic PFS per Prostate Cancer Clinical Trials Working Group 3 was 3.7 months (95% CI: 2.0-5.4). Acapatamab induced T-cell activation and increased cytokine production several-fold within 24 hours of initiation. Treatment-emergent antidrug antibodies were detected in 55% and impacted serum exposures in 36% of patients in dose expansion. Acapatamab was safe and tolerated and had a manageable CRS profile. Preliminary signs of efficacy with limited durable antitumor activity were observed. Acapatamab demonstrated pharmacokinetic and pharmacodynamic activity.

Mosunetuzumab Safety Profile in Patients With Relapsed/Refractory B-cell Non-Hodgkin Lymphoma: Clinical Management Experience From a Pivotal Phase I/II Trial

BackgroundMosunetuzumab is a CD20xCD3 T-cell engaging bispecific antibody approved in Europe and the United States for relapsed/refractory (R/R) follicular lymphoma (FL) after ≥ 2 prior therapies. Materials and MethodsWe present interim safety data from the mosunetuzumab GO29781 (NCT02500407) phase I/II dose-escalation study in R/R non-Hodgkin lymphoma (NHL), focusing on FL. ResultsOverall, 218 patients with R/R NHL, including 90 with R/R FL, received a median of eight 21-day cycles of intravenous mosunetuzumab with step-up dosing in Cycle (C) 1 (C1 Day [D] 1, 1 mg; C1D8, 2 mg; C1D15/C2D1, 60 mg; C3D1 and onwards, 30 mg). Cytokine release syndrome (CRS) was the most common adverse event (AE), occurring in 39.4% (NHL) and 44.4% (FL) of patients. Events occurred predominantly during C1 at the first loading dose; the majority were grade 1/2. CRS events were managed at the investigator's discretion with supportive care, steroids, and tocilizumab, based on protocol management guidelines. Immune effector cell-associated neurotoxicity syndrome was uncommon, reported in 0.9% (NHL) and 1.1% (FL) of patients. Neutropenia occurred in 27.5% (NHL) and 28.9% (FL) of patients (mostly grade 3/4) and could be effectively managed using granulocyte colony-stimulating factor. Tumor lysis syndrome occurred in 0.9% (NHL) and 1.1% (FL) of patients (all grade 3/4 with CRS; all resolved). ConclusionMosunetuzumab monotherapy as treatment for R/R B-cell NHL, including FL, was associated with low rates of severe AEs (including CRS) and is suitable for outpatient administration in the community setting. Adapted protocol guidance for the management of select AEs during mosunetuzumab treatment is included.

Mitigating the Risk of Cytokine Release Syndrome (CRS): Preliminary Results from a DLBCL Cohort of Epcore NHL-1

Background: Epcoritamab SC, a CD3xCD20 T-cell-engaging bispecific antibody, has recently been approved by the US FDA for the treatment of adults with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL), not otherwise specified, including DLBCL arising from indolent lymphoma, and high-grade B-cell lymphoma after ≥2 lines of systemic therapy. As a single agent, epcoritamab SC has demonstrated deep, durable responses with a manageable safety profile in patients with R/R large B-cell lymphoma in the expansion portion of the phase 1/2 EPCORE ™ NHL-1 trial (NCT03625037). Cytokine release syndrome (CRS) events in the dose expansion part of the trial were primarily low grade (49.7% overall; 31.8% grade [G] 1, 15.3% G2, 2.5% G3); timing was predictable, and the majority of events occurred following the first full dose at cycle 1 day 15 (C1D15). To mitigate CRS in dose expansion, subcutaneous administration, step-up dosing, and premedication, including prednisolone, were used. Here, we present preliminary results from a DLBCL optimization cohort of the EPCORE NHL-1 trial that further investigates mitigating the risk of CRS in patients treated with epcoritamab SC monotherapy. Methods: Adult patients with R/R CD20 + DLBCL (previously treated with ≥2 lines of systemic therapy) were enrolled to receive epcoritamab SC in 28-d cycles as follows: weekly, C1-3; every 2 weeks, C4-9; every 4 weeks, C≥10 until progressive disease or unacceptable toxicity. Patients received 2 step-up doses (step-up dose 1, 0.16 mg, and step-up dose 2, 0.8 mg) followed by 48-mg full doses. To further mitigate CRS, C1 of the optimization cohort included mandatory administration of dexamethasone 15 mg as premedication on D1, D8, D15, and D22 and as prophylaxis on D2-4, D9-11, D16-18, and D23-25, and diphenhydramine and acetaminophen as premedication on D1, D8, D15, and D22 with each dose. In C1, it was strongly recommended that patients be well hydrated and that antihypertensive medications be held for 24 h prior to epcoritamab SC administration. Patients were also encouraged to monitor their temperatures following the first 4 doses. Hospitalization and inpatient observation were optional. The primary endpoint was rate of G2 or higher CRS and all CRS events. Secondary pharmacokinetic/pharmacodynamic (PK/PD) analyses were performed. Results: As of April 21, 2023, 24 patients (median age, 65 y) had been treated in this DLBCL optimization cohort. The median number of prior lines of treatment was 3 (range, 2-10), 75% of patients were primary refractory, 71% had stage IV disease, and 58% had prior CAR T. With a median follow-up of 1.3 mo, 18 patients (75%) remained on treatment. The most common treatment-emergent AEs (TEAEs) of any grade were infections (38%; COVID-19, 8%), fatigue (21%), CRS (17%), headache (17%), anemia (13%), constipation (13%), decreased platelet count (13%), dyspnea (13%), hyponatremia (13%), insomnia (13%), and neutropenia (13%; febrile neutropenia, 4%). All CRS events were G1; 1 patient was treated with anticytokine therapy (tocilizumab); there were no treatment discontinuations due to CRS. The most commonly observed CRS symptom was fever (100%). Most CRS events (3/5 events) occurred following the first full dose on C1D15. The median time to CRS resolution was 3.5 d (range, 1-25) and all events resolved. Compared with the DLBCL expansion cohort, circulating interleukin 6 (IL-6) levels were decreased 24 h after the first full dose (C1D15) of epcoritamab SC ( Figure). The median circulating IL-6 level at C1D16 was lower in the dose optimization cohort at 6.92 pg/mL (2.97 pg/mL at C1D1 predose), compared with 21.24 pg/mL (2.45 pg/mL at C1D1 predose) in the DLBCL expansion cohort. The addition of dexamethasone and fluids in optimization did not appear to interfere with T-cell margination or T-cell activation, given that the fold-change values of T-cell absolute counts and percentage of activated T cells were similar between DLBCL optimization and expansion cohorts at C1D16. No patients experienced ICANS, clinical tumor lysis syndrome, or fatal TEAEs. Conclusions: Encouraging preliminary data from this DLBCL CRS optimization cohort, which incorporates prophylactic dexamethasone and hydration of patients during cycle 1, indicate that this approach is effective in decreasing rates and severity of CRS. Data with additional patients and follow-up will be presented.

Mosunetuzumab Monotherapy Demonstrates Activity and a Manageable Safety Profile in Patients with Relapsed or Refractory Richter's Transformation

Background: Richter's transformation (RT) is characterized by the development of chronic lymphocytic leukemia to an aggressive lymphoma, most commonly CD20+ large B-cell lymphoma. RT remains an unmet medical need with a poor prognosis and no standard of care. Mosunetuzumab is a CD20xCD3 T-cell engaging bispecific antibody that redirects T cells to eliminate malignant B cells. In a Phase I/II study (NCT02500407), fixed-duration mosunetuzumab monotherapy demonstrated notable efficacy and a manageable safety profile in patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (Bartlett et al. Blood Advances 2023). We report the efficacy and safety of mosunetuzumab monotherapy in patients with R/R RT after a median follow-up of 8.7 (range: 1-37) months. Methods: Eligible patients with R/R RT and ≥1 prior therapies were enrolled. Patients with lymphocyte counts of ≥5000/µL were excluded. Mosunetuzumab was administered intravenously in 21-day cycles with step-up dosing in Cycle (C) 1 (C1 Day [D] 1, 1mg; C1D8, 2mg; C1D15/C2D1, 60mg; C3D1 and onwards, 30mg). Hospitalization for treatment was not required. Patients achieving a complete response (CR) by C8 completed treatment without additional cycles; patients with a partial response (PR) or stable disease received a total of 17 cycles. The primary endpoints were safety and tolerability. Efficacy was a secondary endpoint and was assessed according to Cheson 2007 criteria. Cytokine release syndrome (CRS) events were graded using the American Society for Transplantation and Cellular Therapy criteria (Lee et al. Biol Blood Marrow Transplant 2019). Results: Twenty patients with R/R RT were enrolled. Median age was 70 (range: 49-87) years, 95.0% of patients had Ann Arbor stage III/IV disease, and 70.0% had an International Prognostic Index score of ≥3. Median number of prior therapies was 2.5 (range: 1-10), 65.0% of patients had ≥2 prior therapies, and 45.0% had received prior treatment with a Bruton tyrosine kinase inhibitor. Overall, 80.0% of patients were refractory to their last therapy. Investigator-assessed overall response and CR rates were 40.0% and 20.0%, respectively. Of four patients with a CR, two had a CR ongoing for ≥20 months at data cut-off (duration of CR [DOCR] at data cut-off: 21.2 months [patient had disease progression at a later timepoint] and 34.2 months), and the other two patients had received a subsequent stem-cell transplant (DOCR with mosunetuzumab: 0.1 and 4.2 months) ( Figure). The four patients with a PR had individual durations of response of: 1.7, 2.1, 2.3, and 2.8 months. The most common adverse event (AE) was CRS (65.0%), and events were predominantly Grade (Gr) 1 (20.0%) or Gr 2 (40.0%); a Gr 3 event was reported after C1D15 in one patient (5.0%). CRS was primarily associated with treatment administration during C1 (C1D1, 15.0%; C1D15, 50.0%); a Gr 1 CRS event was reported in one patient (5.0%) during C2. Of the 14 patients with CRS, six (42.9%) received tocilizumab, three (21.4%) received low-flow oxygen, one (7.1%) received a single pressor, and four (28.6%) received steroids; of the patients who received steroids, two (14.3%) received both tocilizumab and steroids. One patient was admitted to the intensive care unit for the management of Gr 3 CRS. The median duration of CRS was 3 (range: 1‒9) days. All CRS events resolved. Neurologic AEs potentially consistent with immune effector cell-associated neurotoxicity syndrome (ICANS), and considered treatment-related, occurred in two patients (Gr 1 ICANS and Gr 2 lethargy, each n=1); both events resolved. ICANS occurred one day after a Gr 2 CRS event. No Gr 5 (fatal) AEs, or AEs leading to treatment discontinuation were reported. AEs of special interest included infections (35.0%), neutropenia (15.0%), thrombocytopenia (20.0%), and tumor flare events (10.0%). Conclusions: In patients with R/R RT, fixed-duration mosunetuzumab monotherapy demonstrates activity with durable responses and a manageable safety profile in a limited sample size of 20 patients. Treatment with mosunetuzumab warrants further study in this patient population with a high unmet medical need.

Glofitamab Plus R-CHOP Induces High Response Rates with a Manageable Safety Profile in Patients with Previously Untreated Diffuse Large B-Cell Lymphoma (DLBCL): A 12-Month Analysis from a Phase Ib Study

Background: Over a third of patients (pts) with DLBCL do not respond or relapse after first-line (1L) treatment with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP; Sarkozy and Sehn. Ann Lymphoma 2019); these pts have limited curative options. Glofitamab (Glofit) is a T-cell engaging bispecific antibody with a novel 2:1 (CD20:CD3) format that allows bivalent binding to CD20 on B cells; this enables combination with anti-CD20 antibodies, including rituximab. Glofit monotherapy has shown durable responses in pts with relapsed/refractory DLBCL (Dickinson et al. NEJM 2022). In the safety run-in and expansion phases of the ongoing NP40126 trial (NCT03467373), Glofit + R-CHOP demonstrated promising efficacy and manageable safety in pts with 1L DLBCL (Topp et al. ASH 2022). Here, we report durability of response beyond 12 months in Glofit + R-CHOP-treated pts with 1L DLBCL from the NP40126 trial. Methods: Pts received R-CHOP for 6-8 three-weekly cycles. Intravenous Glofit was given with step-up dosing during Cycle (C)2 (Day [D]8, 2.5mg; D15, 10mg) and at the target dose (30mg) from C3D8 onwards. Glofit maintenance was allowed for up to one year. Efficacy was analyzed in all pts who had been on the study long enough to have a protocol scheduled end-of-treatment response assessment. Safety was analyzed in all pts who received at least one dose of any study drug. Response was assessed by PET-CT using Lugano criteria (Cheson et al. JCO 2014). Cytokine release syndrome (CRS) events were graded using the American Society for Transplantation and Cellular Therapy criteria (Lee et al. Biol Blood Marrow Transplant 2019) and other adverse events (AEs) by the Common Terminology Criteria for Adverse Events (v4.0). Hospitalization was not mandated for Glofit. Results: As of April 4, 2023, 56 pts were enrolled in this cohort. Median age was 68 years (range: 21-84), 54 pts (96.4%) had Ann Arbor stage III/IV disease, and median International Prognostic Index (IPI) score was 3 (IPI 1: 3.6% [2/56], IPI 2: 33.9% [19/56], IPI 3: 35.7% [20/56], IPI 4: 23.2% [13/56], IPI 5: 3.6% [2/56]). The cell of origin was germinal center B-cell (GCB) in 25 (44.6%) pts and non-GCB in 11 (19.6%) pts. After 17.1 (range: 0-26) months of median follow-up, the best overall response rate was 92.9% (52/56) and the complete metabolic response (CMR) rate was 83.9% (47/56). Median time to CMR was 1.8 months (95% confidence interval [CI]: 1.6-4.7). Most CMRs (44/47; 93.6%) were ongoing at data cut-off ( Figure). Among complete responders, the Kaplan-Meier estimated probability of ongoing responses at 12 months was 91.5% (95% CI: 82.2-100). Median duration of response and duration of complete response were not reached at data cut-off. The incidence of AEs and serious AEs (SAEs) were similar compared with earlier analyses. Grade (Gr) ≥3 AEs occurred in 42 (75.0%) pts and Gr ≥3 AEs related to Glofit in 14 (25.0%) pts. SAEs were reported in 20 (35.7%) pts and SAEs related to Glofit in six (10.7%) pts. Gr 5 AEs were reported in four (7.1%) pts (COVID-19 pneumonia, n=3; infusion related reaction associated with rituximab, n=1). AEs leading to dose interruption of Glofit occurred in 12 (21.4%) pts. Median dose intensity was 100% for all R-CHOP components. AEs leading to discontinuation of Glofit occurred in one (1.8%) patient. CRS events were reported in six (10.7%) pts: Gr 1, n=4; Gr 2, n=2; no Gr 3/4 CRS events were reported. All CRS events occurred during C2-3. Tocilizumab was used in two (33.3%) pts with CRS. Neurologic AEs (NAEs) occurred in 23 (41.1%) pts (most common NAEs (>5%) were peripheral neuropathy, n=7 [12.5%]; paraesthesia, n=5 [8.9%]; insomnia, n=4 [7.1%]; headache, n=3 [5.4%]); Gr 3 NAEs included cerebrovascular accident (n=1) and herpes zoster (n=1). No Glofit-related NAEs consistent with immune effector cell-associated neurotoxicity syndrome were reported. Neutropenia was reported in 26 (46.4%) pts (Gr ≥3 neutropenia: Gr 3, n=5; Gr 4, n=19). Infections and infestations were reported in 27 (48.2%) pts (of which the majority were Gr ≤2 [17/27]); Gr 3, n=7; Gr 5, n=3. Conclusions: Glofit + R-CHOP had a manageable safety profile with a low incidence of CRS, and continued to demonstrate durable responses with an improved CMR rate since the last data cut-off. These findings support the potential for favorable long-term outcomes with Glofit + R-CHOP as 1L treatment of DLBCL. Further analyses, including circulating tumor DNA data, will be presented.

Glofitamab Monotherapy in Relapsed or Refractory Large B-Cell Lymphoma: Extended Follow-Up from a Pivotal Phase II Study and Subgroup Analyses in Patients with Prior Chimeric Antigen Receptor T-Cell Therapy and by Baseline Total Metabolic Tumor Volume

Background: Glofitamab is a CD20xCD3 bispecific antibody with a 2:1 (CD20:CD3) format that engages and redirects T cells to eliminate B cells. In a pivotal Phase II study (NCT03075696), fixed-duration glofitamab monotherapy induced high complete response (CR) rates and had a manageable safety profile in patients with relapsed and/or refractory (R/R) large B-cell lymphoma (LBCL; Dickinson et al. N Engl J Med 2022). Here, we present an extended follow up, as well as subgroup analyses in patients with prior chimeric antigen receptor (CAR) T-cell therapy and by baseline total metabolic tumor volume (TMTV). Methods: Patients with LBCL and ≥2 prior therapies received obinutuzumab pretreatment (1000mg) on Day (D) 1 of Cycle (C) 1. Intravenous glofitamab was then given as step-up doses during C1 (2.5mg on D8; 10mg on D15), followed by the target dose (30mg) on D1 of C2-12 (21-day cycles; total of 8.3 months). The primary endpoint was independent review committee (IRC)-assessed CR rate using Lugano criteria (Cheson et al. J Clin Oncol 2014). Cytokine release syndrome (CRS) events were assessed using American Society for Transplantation and Cellular Therapy criteria (Lee et al. Biol Blood Marrow Transplant 2019). Exploratory analyses were performed to investigate the association between TMTV at baseline and progression-free survival (PFS) and CRS. As there is currently no consensus on the method for standardized uptake value (SUV) thresholding in non-Hodgkin's lymphoma, a variety of methods are used in clinical studies (Keijzer et al. Comput Struct Biotechnol J 2023). Here, we used IRC-assessed TMTV derived from baseline positron emission tomography images using a semi-automatic method with a threshold for TMTV of 2x the SUV mean of the liver. Results: As of May 1, 2023, 155 patients were enrolled; 154 patients had received ≥1 dose of study treatment. Baseline characteristics were as previously presented (Dickinson et al. N Engl J Med 2022): median prior therapies received was 3 (range: 2-7); 33% of patients had received prior CAR T-cell therapy, and 85% were refractory to their most recent regimen. Median time on study was 25.8 months (range: 0-35). The IRC-assessed overall response and CR rates were 52% and 40%, respectively. The majority of CRs (40/62; 65%) were ongoing at data cut-off. Median duration of CR (DoCR) was 26.9 months (95% confidence interval [CI]: 18.4-not evaluable [NE]); an estimated 67% of patients with a CR at any time remained in remission at 18 months. PFS and overall survival rates at 12 months in patients with a CR at end of treatment (EOT) were 80% and 90%, respectively. In patients with prior CAR T-cell therapy (n=52), CR rates were consistent with the overall population (N=155; 37% vs 40%, respectively) and median DoCR was 22.0 months (95% CI: 6.7-NE). The safety profile of glofitamab was consistent with what has been described previously, with no new safety signals observed. Baseline TMTV was available for 144 patients and the median was 128.7mL (range: 0-3820; data cut-off: January 16, 2023). Higher TMTV was associated with an increased risk of experiencing a Grade ≥2 CRS event. The proportion of patients with Grade ≥2 CRS events in the first, second, third, and fourth TMTV quartiles was 2.8%, 11.1%, 16.7%, and 38.9%, respectively (Chi-square=16.273; degrees of freedom=1; p<0.0001). Patients with a baseline TMTV above or equal to the median (n=72) had a 12-month PFS rate of 16.8% (95% CI: 9.7-29.1), compared with 50.1% (95% CI: 39.5- 63.7) amongst patients with a baseline TMTV below the median (n=72; hazard ratio: 2.6, 95% CI: 1.7-3.9; Figure). Conclusions: Glofitamab continued to demonstrate durable responses in patients with R/R LBCL, with most patients with CR at EOT still in remission, and no new safety signals observed. These data indicate that there may be potential for favorable long-term outcomes with fixed-duration glofitamab for R/R LBCL. CR rates in patients with prior CAR T-cell therapy were durable and consistent with the overall population. Data from the subgroup analyses showed that higher baseline TMTV was associated with an increased risk of Grade ≥2 CRS and suggested that baseline TMTV may be prognostic for PFS. Updated analyses, with a follow-up of approximately 24 months post EOT, and further TMTV exploratory analyses will be presented.

Mosunetuzumab Monotherapy Continues to Demonstrate Durable Responses in Patients with Relapsed and/or Refractory Follicular Lymphoma after ≥2 Prior Therapies: 3-Year Follow-up from a Pivotal Phase II Study

Background: Mosunetuzumab is a CD20xCD3 T-cell engaging bispecific antibody that redirects T cells to eliminate malignant B cells. In a pivotal Phase II study (NCT02500407), mosunetuzumab demonstrated a high complete response (CR) rate with a manageable safety profile in patients with relapsed/refractory (R/R) follicular lymphoma (FL) and ≥2 prior lines of therapy (Budde et al. Lancet Oncol 2022). Mosunetuzumab is a fixed-duration treatment that can be administered in an outpatient setting. Here, we present updated data for patients with R/R FL and ≥2 prior lines of therapy, after 3 years of follow-up. Methods: Eligible patients with R/R FL Grade (Gr) 1-3a and ≥2 prior therapies received intravenous mosunetuzumab in 21-day cycles with step-up dosing in Cycle (C) 1 (C1 Day [D] 1, 1mg; C1D8, 2mg; C1D15/C2D1, 60mg; C3D1 and onwards, 30mg). Hospitalization for treatment was not required. Patients achieving a CR by C8 completed treatment without additional cycles; patients with a partial response or stable disease received a total of 17 cycles. The primary endpoint was CR rate as determined by an Independent Review Committee (as best response; Cheson 2007 criteria). Duration of response (DOR), duration of complete response (DOCR), progression-free survival (PFS), event-free survival (EFS), and safety were secondary endpoints. Time to next treatment (TTNT), response to retreatment, biomarkers of minimal residual disease (MRD), and circulating B-cell counts were exploratory endpoints. Results: Ninety patients with R/R FL were enrolled. As of May 2, 2023, median time on study was 37.4 (range: 2.0-48.0) months. Investigator-assessed best overall response and CR rates were 77.8% (95% CI: 67.8-85.9) and 60.0% (95% CI: 49.1-70.2), respectively. The median DOR was 35.9 months (95% CI: 20.7-not reached [NR]). Median DOCR was NR (95% CI: 33.0-NR); the estimated 30-month DOCR rate was 72.4% (95% CI: 59.2-85.6) ( Table). Three years after the end of treatment, 57.1% of 70 responding patients were alive and disease progression-free. Median PFS was 24.0 months (95% CI: 12.0-NR) ( Figure). The median TTNT was 37.3 months (95% CI: 18.0-NR); estimated EFS at 36 months was 51.8% (95% CI: 40.8-62.8). After initial mosunetuzumab treatment, 34/90 (37.8%) patients had received a new anti-lymphoma therapy, including 33/90 (36.7%) patients who received a new systemic treatment (8/33 [24.2%] of these patients received chimeric antigen receptor T-cell therapy); 8/90 (8.9%) had radiotherapy; 2/90 (2.2%) had excision of tumor; 2/90 (2.2%) had an allogeneic stem cell transplant; and 1/90 (1.1%) had an autologous stem cell transplant. Five patients received retreatment with mosunetuzumab, 3/5 of these patients had a CR. No new cytokine release syndrome (CRS) events, serious, or Gr ≥3 adverse events (AEs) were reported since the previous analysis (median follow-up of 28.3 months; Bartlett et al. ASH 2022). CRS events occurred in 44.4% of patients and 2.2% were Gr 3/4 in severity; all CRS events resolved. Overall AEs and serious AEs were comparable to the previous analysis (Bartlett et al. ASH 2022); febrile neutropenia was not reported. Forty-six (51.1%) patients experienced Gr 3/4 AEs related to mosunetuzumab; the rate of AEs leading to discontinuation was low (4.4%). Peripheral blood B-cell depletion following treatment with mosunetuzumab occurred in all patients, and recovery was observed after a median of 18 months following the end of treatment in patients with a sustained response using follow-up samples. MRD kinetics following mosunetuzumab therapy will be presented. Conclusions: In this updated analysis, with a median follow-up of 37.4 months, durable responses continued to be observed with fixed-duration mosunetuzumab in patients with R/R FL. The manageable safety profile was consistent with previous reports. Evidence of B-cell recovery was observed after a median of 18 months following the end of treatment.

Assessment of Early Intervention Strategies for Management of Cytokine Release Syndrome and Neurologic Events after Brexucabtagene Autoleucel (Brexu-Cel) Treatment in Patients with Relapsed or Refractory Mantle Cell Lymphoma (R/R MCL) in ZUMA-2

Introduction: Brexu-cel is an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy approved in the United States for the treatment of adults with R/R MCL and in the European Union for adults with R/R MCL after ≥2 prior therapies, including a Bruton tyrosine kinase inhibitor (BTKi). In the Phase 2 ZUMA-2 study, with a median follow-up of 35.6 months, brexu-cel showed an objective response rate of 91%, a median duration of response of 28.2 months, and a median overall survival of 46.6 months with a manageable safety profile in treated patients (pts) with R/R MCL (N=68). Grade (Gr) ≥3 infections, cytokine release syndrome (CRS), and neurologic events (NEs) occurred in 37%, 15%, and 31% of pts, respectively (Wang et al. J Clin Oncol. 2023). In August 2018, CRS and NE management strategies for ZUMA-2 were updated to initiate treatment of these adverse events earlier at the onset of Gr 1 events to improve safety outcomes. Here, we report 4-yr safety outcomes for pts in ZUMA-2 by initial and updated CRS and NE management strategies. Methods: Pts with R/R MCL and ≤5 prior treatments, including a BTKi, underwent leukapheresis and conditioning chemotherapy followed by a single infusion of brexu-cel (2×10 6 CAR T cells/kg). For CRS, the initial toxicity management strategy was to consider tocilizumab ± corticosteroids (methylprednisolone 1 mg/kg bid or dexamethasone 10 mg q6h) for Gr 2 CRS with extensive comorbidities or older age and Gr 3 CRS, and to increase the dose of corticosteroids (methylprednisolone 1 g/day x3, followed by a rapid taper consisting of 250 mg bid x2 days, 125 mg bid x2 days and then 60 mg bid x2 days) for Gr 4 CRS. The updated guidance was to administer tocilizumab for Gr 1/2 CRS that does not improve after 24 hours, and tocilizumab + corticosteroids (only if no resolution after 24 hours) and vasopressors for Gr 2 and 3 CRS. For NEs, the initial guidance was to consider use of tocilizumab for Gr 2 NEs only if other comorbid conditions exist (8 mg/kg IV over 1 hour, not to exceed 800 mg) and to add corticosteroids (dexamethasone 10 mg IV q6h, methylprednisolone 1 mg/kg bid) for Gr ≥3 NEs. In the updated guidance, steroid treatment without concurrent CRS remained the same, but both tocilizumab + dexamethasone 10 mg IV were to be administered for Gr ≥2 NEs concurrent with CRS. Both guidance protocols recommended treatment with antibiotics for management of infections. This exploratory post hoc analysis examined safety outcomes related to CRS, NEs, and infections for pts in each management group, with descriptive statistics reported. Results: As of July 23 2022, the median follow-up in the 68 treated pts was 47.5 months (range, 37.9-68.3). Of these pts, 40 received updated guidance (early intervention group [EIG]) and 28 received initial guidance (later intervention group [LIG]). Gr ≥3 CRS events were experienced at similar rates in both groups while Gr ≥3 NEs and Gr ≥3 infections occurred less often in the EIG vs the LIG (Table). Gr 5 infections occurred in 2 pts in the EIG and 0 pts in the LIG. No Gr 5 CRS or NEs occurred in either group. The median durations of Gr ≥3 CRS and infections were shorter for the EIG than the LIG while the median duration of Gr ≥3 NEs was longer for the EIG. Any Gr CRS and NEs were resolved at similar rates in both groups, but fewer any Gr infections were resolved for the EIG (all unresolved events in both groups were due to pt death before event resolution). Concomitant medications of interest were used in 80% (n=32) and 82% (n=23) of pts in the EIG and LIG, respectively. Tocilizumab was used at similar rates in the EIG and LIG (73% vs 68%), but steroids (55% vs 68%), vasopressors (18% vs 29%), and immunoglobulins (28% vs 50%) were used at lower rates in the EIG. Median CAR T-cell peak levels and area under the curve were lower for the EIG than the LIG while median CAR T-cell levels peaked at similar times in both groups. Conclusions: With an updated safety management protocol emphasizing early intervention with tocilizumab and corticosteroids for CRS and NEs, only 20% of pts had Gr ≥3 NEs and 30% had Gr ≥3 infections. Additionally, a lower percentage of EIG pts required steroid, vasopressor, and immunoglobulin use than pts in the LIG. CAR T-cell expansion levels were numerically lower in the EIG. Although limited by small pt numbers, these findings support the current clinical guidance for safety management during brexu-cel treatment, which is close to the ZUMA-2 updated toxicity management guidance that was examined in this study.

New Tocilizumab (TCZ) Dosing Guidance for T-Cell Engaging Bispecific Antibody-Related Cytokine Release Syndrome (CRS) in Patients (pts) with Relapsed/Refractory (R/R) B-Cell Non-Hodgkin Lymphoma (B-NHL): Insights from Pooled Clinical Trial Safety Experience and Quantitative Clinical Pharmacology (qCP) Analyses

Background: Mosunetuzumab (Mosun), approved for treatment of pts with R/R follicular lymphoma (FL) and ≥2 prior therapies, and glofitamab (Glofit), approved for treatment of pts with R/R diffuse large B-cell lymphoma, or large B-cell lymphoma arising from FL, and ≥2 prior therapies, are CD20xCD3 T-cell engaging bispecific antibodies that redirect T cells to eliminate B cells. CRS is a common on-target adverse event observed with bispecific antibodies and associated with exposure. TCZ, a humanized anti-interleukin-6 (IL-6) receptor, is often used for CRS management. TCZ dosing recommendations derived from CAR T-cell studies (Le et al. Oncologist 2018) may not be optimal for bispecific antibody-treated pts. Using TCZ clinical usage patterns in Mosun- or Glofit-treated pts with R/R B-NHL, qCP, and cytokine analyses, we explored a new TCZ dosing regimen for CRS management (for pts >30 kg body weight). Methods: Pooled safety data from seven Phase I/II studies evaluating Mosun or Glofit in pts with R/R B-NHL were analyzed. CRS was graded using ASTCT criteria (Lee et al. Biol Blood Marrow Transplant 2019). Modeling was used to predict TCZ concentrations (conc) and soluble IL-6 receptor (s-IL6R) occupancy over time, following administration of different TCZ dosing regimens in a subset of pts. Downstream cytokine pharmacodynamic responses (IL-6 and C-reactive protein [CRP]) were evaluated graphically post-TCZ dosing. Results: Data from 733 Mosun- and 772 Glofit-treated pts across different Mosun/Glofit dose levels were analyzed; of these, 232 (31.7%) and 427 (55.3%) pts, respectively, had ≥1 CRS event, and 36/232 (15.5%) and 140/427 (32.8%) pts received TCZ for CRS management. CRS events were mainly Grade 1/2 and occurred during the first treatment cycle. Most pts who received TCZ for CRS received ≤2 doses of TCZ overall (Mosun: 94.4%; Glofit: 84.2%) ( Table), and 1 dose of TCZ for the management of a single CRS event (Mosun: 91.7%; Glofit: 84.9%). CRS resolution was achieved within 3 days of TCZ administration in 75.0% and 66.9% of Mosun- and Glofit-treated pts, respectively. By then, a reduction in IL-6 and CRP levels was also observed. In a prior pharmacokinetic (PK) analysis of TCZ in pts with CAR T-cell-associated CRS, predicted TCZ conc after administration of 4 intravenous (IV) TCZ doses of 8 mg/kg every 8 hours (q8h) was generally below 649 μg/mL, the observed maximum conc in healthy volunteers and “safety threshold” used by the FDA (Le et al. Oncologist 2018). qCP analyses of TCZ PK and s-IL6R data from 67 pts who received TCZ for CRS management following treatment with Mosun or Glofit indicated that this TCZ regimen may exceed the safety threshold, in part because maximum TCZ conc is one-third lower in pts with CAR T-cell-induced CRS vs bispecific antibody-induced CRS. In addition, typical bispecific antibody regimens involve multiple doses compared with a single CAR T-cell infusion, with the potential for multiple CRS events requiring TCZ treatment; therefore, TCZ accumulation must be considered. qCP simulations predicted that for 1 x 8 mg/kg dose, median duration of >90% s-IL6R saturation was 28 (range: 14-28) days ( Table). Furthermore, simulations indicated that ≤2 consecutive TCZ doses q8h per CRS event and a maximum of 3 TCZ doses within a 6-week time period maintain the TCZ conc below the FDA safety threshold, while ensuring sustained s-IL6R occupancy ( Table). Conclusions: qCP results and clinical experience in Mosun and Glofit studies support a TCZ dosing regimen of ≤2 IV doses of 8 mg/kg per CRS event administered q8h, not exceeding a total of 3 doses within a 6-week period. Further improvement in CRS management and symptom resolution with additional TCZ doses is unlikely given the predicted duration of s-IL6R occupancy and observed rapid decline in systemic inflammatory markers post dosing. This proposed TCZ dosing regimen reflects TCZ usage patterns in clinical trials evaluating Mosun and Glofit, and is included in their Summaries of Product Characteristics. In patients with R/R B-NHL receiving bispecific antibody treatment, TCZ is generally suitable for management of acute CRS, and balances risk-benefit for potential scenarios involving multiple TCZ administrations for pts with CRS recurrence. This recommendation considers TCZ safety factors, the unique PK properties of TCZ in this setting and the expected duration of activity based on pharmacological modeling of target binding (s-IL6R occupancy).

Clinical Factors Associated with Cytokine Release Syndrome and Dosing Recommendations for Restarting Elranatamab Following an Interruption

BACKGROUND In the MagnetisMM-3 (NCT04649359) study, elranatamab (ELRA) administered at a dose of 76 mg once-weekly (QW) with 2 step-up priming doses of 12 mg on day 1 and 32 mg on day 4 had a manageable safety profile, with 56.3% of patients developing cytokine release syndrome (CRS) and 98.8% of events occurring with the first 3 doses. Here, we report clinical factors associated with CRS and dosing recommendations for restarting treatment after dose interruptions in patients with relapsed or refractory multiple myeloma (RRMM) undergoing treatment with ELRA. METHODS Eligible patients received ELRA subcutaneously in step-up priming doses of 12 and 32 mg on days 1 and 4 of cycle 1, respectively, followed by 76 mg of ELRA QW. CRS events were graded according to the criteria of the American Society for Transplantation and Cellular Therapy and managed according to published guidelines. Multivariable analyses were performed to identify clinical factors associated with CRS. Baseline factors (extramedullary disease by BICR, prior antibody-drug conjugate, prior CAR-T, number of prior lines of therapy [≤5, >5], sex, and age [continuous variable]) were included in the model for CRS after the initial dose, and only post-baseline factors (time to previous CRS and time to initial tocilizumab use) were included in the model for CRS after the second dose. A previously described population pharmacokinetic (PK) model was used to simulate different interruption scenarios and determine how long it takes for ELRA exposure to drop below the threshold associated with CRS events (Hibma J, et al. Poster presented at PAGE 31 2023 [abstract 10648]). The data used to develop this model was collected from the following open-label elranatamab trials: MagnetisMM-1 (NCT03269136; phase 1), MagnetisMM-2 (NCT04798586; phase 1), MagnetisMM-3 (NCT04649359; phase 2), and MagnetisMM-9 (NCT05014412; phase 1/2). Of 183 patients who were treated in MagnetisMM-3 with the 2 step-up priming dosing, 106 patients (57.9%) experienced CRS, 43.7% grade 1, 13.7% grade 2, and 0.5% grade 3. Tocilizumab was used to manage CRS. Of the 130 CRS events, 37 (28.5%; 20 grade 1 and 17 grade ≥2) were treated with tocilizumab, and 93 (71.5%; 82 grade 1 and 11 grade ≥2) were not. After the initial elranatamab dose, 79/183 patients had CRS. The presence of extramedullary disease was predictive of a decreased risk of CRS after the initial dose. Of the 180 who received a second elranatamab dose, 35 had CRS afterwards. In a multivariable model also adjusting for CRS after the initial dose, prior tocilizumab use was predictive of a decreased risk of CRS after the second dose. After receiving doses of 76 mg of ELRA, 16 instances of dose delays lasting >6 to ≤12 weeks were observed. In most of these instances (11/16; 68.8%), patients did not repeat the 32-mg step-up dose. In 5 instances, patients restarted treatment with 32 mg of ELRA. No patients experienced CRS after retreatment. For the 4 instances of dose delays lasting >12 weeks after a 76-mg dose, patients repeated the 32-mg step-up dose in 2 instances, and patients received >32 mg ELRA after the interruption in the other 2 instances, with none experiencing CRS after retreatment. With dose delays of 6-12 weeks, ELRA exposure decreases below the C max after a 32-mg dose but not less than that for the 12-mg dose. With dose delays >12 weeks, ELRA exposure decreases below the C max after a 12-mg dose. To minimize the risk of CRS events after dose interruptions, clinical and PK data and modeling were used to develop recommendations for restarting therapy (Figure). CONCLUSIONS Extramedullary disease and use of tocilizumab were associated with a decreased risk of CRS. Based on clinical and PK data and modeling, it is recommended that patients receiving 76 mg ELRA who then experience dose delays lasting 6-12 or >12 weeks should restart treatment at doses of 32 or 12 mg, respectively.

Mosunetuzumab Plus Polatuzumab Vedotin Demonstrates a Favorable Safety Profile and Efficacy in Patients (Pts) with Relapsed or Refractory (R/R) Large B-Cell Lymphoma (LBCL): Primary Analysis of a Phase Ib/II Study

Background: Mosunetuzumab (Mosun) is a CD20xCD3 T-cell engaging bispecific antibody that engages and redirects T cells to eliminate malignant B cells. The ongoing Phase Ib/II GO40516 study (NCT03671018) investigates Mosun in combination with polatuzumab vedotin (Pola; M-Pola) in pts with B-cell non-Hodgkin lymphoma (B-NHL). The Phase II expansion phase of the M-Pola regimen (with conventional Mosun and Pola dose and dose schedule), showed an acceptable safety profile and promising anti-tumor activity in pts with R/R B-NHL at interim analysis (Budde et al. ASH 2021). With enrollment complete, we present full dose-expansion cohort results. Methods: Eligible pts had confirmed R/R LBCL (including diffuse LBCL not otherwise specified, high-grade B-cell lymphoma [HGBCL], transformed follicular lymphoma [tFL], and follicular lymphoma [FL] grade [Gr] 3b) and had received ≥1 prior line of therapy (including an anti-CD20 antibody). Treatment cycles were 21 days. Pola (1.8mg/kg; intravenous [IV]) was administered on Day (D) 1 of Cycles (C) 1-6. Mosun IV was administered with C1 step-up dosing to mitigate cytokine release syndrome (CRS), with the following dose and dose schedule: 1mg on C1D1, 2mg on C1D8, 60mg on C1D15 and C2D1, and 30mg on D1 of C3+. Pts with a complete response (CR) completed Mosun after C8, and pts with stable disease or partial response at the end of C8 continued Mosun for a total of 17 cycles. Primary endpoint was best overall response rate (ORR) by independent review committee (IRC) using Lugano 2014 criteria (Cheson et al. J Clin Oncol 2014). CRS events were reported using ASTCT criteria (Lee et al. Biol Blood Marrow Transplant 2019). Results: As of April 7, 2023, 98 pts received M-Pola in the dose-expansion cohort. Median age was 68.0 years (range: 20-88), 71.4% were male, 87.8% had de novo DLBCL, 8.2% had tFL, 4.1% had Gr 3b FL, 18.4% had HGBCL (including double/triple-hit lymphoma), 7.1% had bulky disease (≥10 cm), 51.0% had an International Prognostic Index score 3-5, and 85.7% had Ann Arbor stage III/IV disease. The median number of prior lines of therapy was 2 (range: 1-8), 35.7% had prior CAR-T therapy, and 11.2% had prior ASCT. Most pts (80.6%) were refractory to prior anti-CD20 therapy, 58.2% were primary refractory, 77.6% were refractory to their previous therapy, and 26.5% were refractory to CAR-T therapy. The median number of cycles received was 8 for Mosun (range: 1-17) and 6 for Pola (range: 1-6). Adverse events (AEs) occurring in ≥15% of pts were fatigue (42.9%), neutropenia (28.6%), nausea (26.5%), diarrhea (23.5%), pyrexia (23.5%), headache (21.4%), CRS (18.4%), chills (17.3%), and peripheral sensory neuropathy (16.3%). Gr 3/4 AEs that occurred in ≥5% pts were neutropenia (20.4%) and fatigue (7.1%). Gr 5 AEs occurred in 3 (3.1%) pts, of which 2 were due to COVID-19 pneumonia and 1 was due to pneumonia. None were considered related to treatment. CRS events were observed in 18.4% of pts: Gr 1 n=11, Gr 2 n=4, Gr 3 n=3. All CRS events were resolved by data cut-off. Three pts received tocilizumab, 2 pts had a vasopressor, 2 pts received high flow oxygen, and 2 pts required ICU admission for CRS. Mosun-related neurologic AEs potentially consistent with immune effector cell-associated neurotoxicity syndrome occurred in 5 pts (5.1%); all were Gr 1/2 except 1 Gr 4 encephalopathy event. Treatment-related neuropathy occurred in 25.5% of pts (all Gr 1/2). Eleven pts (11.2%) discontinued treatment due to AEs, of which 5 (5.1%) were treatment-related: 1 (1.0%) due to encephalopathy (Mosun-related) and 4 (4.1%) due to peripheral neuropathy (Pola-related). Investigator-assessed ORR and CR rate were 62.2% and 50.0%, respectively ( Table). Median duration of response was not reached (NR; 95% confidence interval [CI]: 11.6-NR); median duration of CR was NR (95% CI: 20.5-NR). Median progression-free survival was 9.6 months (95% CI: 5.6-18.6) and overall survival was 23.3 months (95% CI: 15.2-NR), with a median follow-up of 18.6 months (95% CI: 17.7-23.7). In pts with prior CAR-T therapy (n=35), the ORR and CR rates were 60.0% and 45.7%, respectively. In primary refractory pts (n=57), the ORR and CR rates were 56.1% and 40.4%, respectively. Conclusions: M-Pola continues to show a favorable safety profile and compelling efficacy in highly refractory pts, including those with prior CAR-T therapy and/or primary refractory disease. Primary analysis data, including IRC responses and biomarker analyses, will be presented.

Dexamethasone is Associated with a Lower Incidence and Severity of Cytokine Release Syndrome Compared with Other Corticosteroid Regimens When Given as Premedication for Glofitamab Monotherapy in Patients with Relapsed/Refractory (R/R) Large B-Cell Lymphoma (LBCL)

Background: Glofitamab, a CD20xCD3 T-cell engaging bispecific antibody with a novel 2:1 (CD20:CD3) format, induced frequent and durable complete responses (CRs) with a manageable safety profile in pivotal expansion cohorts of an ongoing Phase I/II study (NCT03075696) in patients (pts) with R/R LBCL (Dickinson et al. NEJM 2022, Falchi et al. ASCO 2023). Cytokine release syndrome (CRS) is a potentially life-threatening toxicity caused by immune activation that can be triggered non-specifically by T-cell engaging therapies. As previously reported, corticosteroid (steroid) premedication was required to prevent or mitigate CRS in pts treated with glofitamab. Dexamethasone (Dex) was mandated in one expansion cohort to assess if this could reduce the rate and severity of CRS versus other steroids. Here, we report data from the dose-escalation and expansion cohorts in pts with R/R LBCL who received Dex only versus non-Dex premedication. Methods: Pts with R/R LBCL (diffuse LBCL not otherwise specified [DLBCL NOS], high-grade B-cell lymphoma [HGBCL], primary mediastinal LBCL [PMBCL], or LBCL arising from follicular lymphoma [trFL]) and ≥2 prior therapies received 1000mg obinutuzumab pretreatment (Gpt) 7 days prior to the first glofitamab dose. IV glofitamab was administered with step-up dosing during Cycle (C) 1 (Day 8, 2.5mg; Day 15, 10mg) followed by the target dose (30mg) on Day 1 of C2-12 (21-day cycles; 8.4 months). Steroid premedication (80mg IV methylprednisolone, or equivalent dose of prednisone [100mg] or prednisolone [100mg], or 20mg IV Dex) was given at least 60 minutes prior to Gpt and each glofitamab dose. Responses were assessed using Lugano criteria (Cheson et al. JCO 2014). CRS events were graded by ASTCT criteria (Lee et al. Biol Blood Marrow Transplant 2019). Results: As of May 1, 2023, 145 pts with R/R LBCL had received glofitamab, including 33 (22.8%) pts (DLBCL NOS, n=24 [72.7%]; HGBCL, n=2 [6.1%]; trFL, n=7 [21.2%]) who received Dex premedication before each glofitamab dose (Dex only cohort) and 112 (77.2%) pts (DLBCL NOS, n=81 [72.3%]; HGBCL, n=5 [4.5%]; PMBCL, n=6 [5.4%]; trFL, n=20 [17.9%]) who had not received Dex premedication before each glofitamab dose (non-Dex cohort). In the Dex only and non-Dex cohorts, median age was 73.0 years (range: 27-86) and 66.0 years (range: 21-90), and 26/33 (78.8%) pts and 83/112 (74.1%) pts had Ann Arbor stage III/IV disease, respectively. Median number of prior therapies was 3.0 for both cohorts. Ten (30.3%) and 37 (33.0%) pts had previously received chimeric antigen receptor T-cell therapy, and 6 (18.3%) and 22 (19.6%) pts had received autologous stem cell transplant in the Dex only and non-Dex cohorts, respectively. Median number of glofitamab cycles was 5.0 in both cohorts. CRS of any grade occurred in 48.5% of pts in the Dex only cohort and 73.2% of pts in the non-Dex cohort, and CRS leading to serious adverse events occurred in 5 (15.2%) and 27 (24.1%) pts, respectively. In both cohorts, CRS events were mostly low grade and primarily occurred during C1 (Table; Figure). Recurring Grade (Gr) ≥2 CRS was not observed in the Dex only cohort and 6 (5.4%) pts had recurring Gr ≥2 CRS in the non-Dex cohort. Median time to CRS onset and median time to resolution were similar in the two cohorts. Treatment discontinuation rate was lower in the Dex only cohort (n=21, 63.6%) versus the non-Dex cohort (n=80, 71.4%), mainly due to progressive disease (Dex only cohort, n=12 [36.4%]; non-Dex cohort, n=52 [46.4%]). In the DLBCL NOS and trFL population, the best overall response assessed by Independent Review Committee was similar between the Dex only (n=31) and non-Dex (n=101) cohorts, with CR reported in 14 (45.2%) and 44 (43.6%) pts, and 12 (38.7%) and 34 (33.7%) pts remaining in CR at data cutoff, respectively. The estimated event-free rate among complete responders at 12 months after the first CR was 83.1% (95% CI: 61.5-100.0) in the Dex only cohort and 77% (95% CI: 63.8-90.2) in the non-Dex cohort. Conclusions: The incidence, severity, and seriousness of CRS after glofitamab administration in pts with R/R LBCL were numerically lower with Dex premedication versus premedication with other steroid regimens. Response rates in the Dex only cohort were similar to those reported in the non-Dex cohort. We therefore propose Dex as the steroid of choice for premedication to prevent or mitigate CRS in pts with LBCL treated with glofitamab monotherapy, considering its half-life and potency.

Fixed Duration Mosunetuzumab Plus Polatuzumab Vedotin Has Promising Efficacy and a Manageable Safety Profile in Patients with BTKi Relapsed/Refractory Mantle Cell Lymphoma: Initial Results from a Phase Ib/II Study

Background: New treatment options are needed for patients (pts) with relapsed/refractory (R/R) mantle cell lymphoma (MCL), especially for pts with progressive disease (PD) after Bruton's tyrosine kinase inhibitor (BTKi) therapy. Outcomes for R/R MCL pts with PD after the BTKi ibrutinib are very poor, demonstrated by a median overall survival of 2.9 months (Martin et al. Blood 2016). While chimeric antigen receptor (CAR) T-cell therapies are approved for pts with R/R MCL; treatment is associated with high toxicity and difficulty with accessibility. Mosunetuzumab (Mosun) is a CD20xCD3 T-cell engaging bispecific antibody that engages and redirects T cells to eliminate malignant B cells. Polatuzumab vedotin (Pola) is a CD79b-targeted antibody-drug conjugate that inhibits cell division and induces apoptosis in B cells. This ongoing Phase Ib/II study (NCT03671018) is investigating Mosun in combination with Pola (M-Pola) in pts with R/R B cell non-Hodgkin lymphoma. Here, we report initial safety and efficacy data from an ongoing Phase II expansion cohort of pts with R/R MCL who had received prior BTKi therapy. Methods: Eligiblepts had histologically confirmed R/R MCL and had received ≥2 prior regimens (including an anti-CD20 agent, BTKi, and anthracycline- or bendamustine-based therapy). Mosun was administered subcutaneously (SC) by step-up dosing on Days (D) 1 (5mg), 8 (45mg), and 15 (45mg) of Cycle (C) 1, then 45mg on D1 of every cycle from C2D1, every 3 weeks for a total of 17 cycles. Pola (1.8mg/kg intravenous [IV] infusion) was administered on D1 of C1-6. All pts received corticosteroid premedication prior to C1 of treatment. From C2, premedication was optional for pts who did not experience cytokine release syndrome (CRS) in the previous cycle. Response was assessed by investigators using Lugano 2014 criteria (Cheson et al. J Clin Oncol 2014). Results: As of October 27, 2022, 20 pts had received M-Pola (n=10 active on treatment, n=1 completed treatment, n=9 discontinued Mosun treatment). Median age of all pts was 68.0 (range: 44-82) years, 75% were male, 95% had Ann Arbor stage III/IV disease, and 40% had a MIPI score ≥6 at study entry. Median number of prior lines of therapy (LOT) was 3 (range: 2-9). All pts had received prior BTKi therapy; 7 pts (35%) had received prior CAR T-cell therapy; and 85% (17/20) of pts were refractory to their last LOT. Median time since last LOT was 1.6 (range: 0-39) months. The proportions of pts with high-risk MCL factors at baseline were: 65% of pts with Ki-67 proliferation index ≥50%; 50% with blastoid/pleomorphic variants; and 20% with TP53 mutation. The overall median time on study was 7.2 (range: 0.4-17.5) months. The most common (≥25%) Mosun and/or Pola-related adverse events (AEs) in all pts (n=20) were CRS (50%), injection site reaction (50%), fatigue (45%), dyspnea (35%), paresthesia (30%), diarrhea (30%), myalgia (30%), infusion-related reaction (25%), and nausea (25%). Two (10%) Grade (Gr) 5 AEs occurred, both of which were due to COVID-19 pneumonia; neither were deemed treatment-related by the investigator. Ten pts (50%) experienced CRS events; 9 pts experienced Gr 1 events, and 1 pt experienced a Gr 2 event, which was managed with tocilizumab and low-flow oxygen. One pt was managed with corticosteroids and no pts required pressors or ICU admission. All CRS events resolved by the data cut-off. Treatment-related neurologic AEs, potentially consistent with ICANs, occurred in 3 pts (15%; Gr 1 confusional state and Gr 2 amnesia, 1 pt; Gr 1 agitation, 1 pt; and Gr 2 memory impairment, 1 pt). Neuropathy occurred in 3 pts (15%); all events were Gr 1. Four pts (20%) had AEs leading to treatment discontinuation: 1 pt with Gr 3 uveitis (related to M-Pola); 1 pt with Gr 3 pneumonitis (related to M-Pola); and 2 pts with Gr 5 COVID-19 pneumonia (both unrelated to M-Pola). Overall response rate (ORR) and complete response (CR) rates were 75% and 70%, respectively (Figure). Best ORR and CR rates were generally consistent in high-risk MCL subgroups (Figure). Median duration of CR was not evaluable (NE; 95% confidence interval: 3.8-NE). Conclusions: Fixed-duration Mosun SC in combination with Pola IV induced high CR rates in pts with R/R MCL who had previously received BTKi therapy, including those in high-risk subgroups and those who had received prior CAR T-cell therapy. CRs were observed early and persisted during the follow up period. M-Pola had a manageable safety profile, and all CRS events were low grade.

Final Analysis of the Phase 2 ELM-2 Study: Odronextamab in Patients with Relapsed/Refractory (R/R) Diffuse Large B-Cell Lymphoma (DLBCL)

Background Odronextamab is a novel, off-the-shelf, CD20×CD3 bispecific antibody that has demonstrated consistent anti-lymphoma activity and a generally manageable safety profile in heavily pretreated patients (pts) with both R/R follicular lymphoma and R/R DLBCL. Encouraging results have been reported in pts who have relapsed following chimeric antigen receptor (CAR) T-cell therapy in the Phase 1 ELM-1 study, and in pts with R/R DLBCL in the Phase 2 ELM-2 study (Kim WS, et al. ASH. 2022). Here, we present the final analysis of the R/R DLBCL cohort from ELM-2 (NCT03888105), reporting long-term efficacy and safety outcomes. Methods Intravenous odronextamab was administered weekly in 21-day cycles during Cycles (C) 1-4. Optimization of the step-up regimen to further mitigate cytokine release syndrome (CRS) was reported previously (Kim WS, et al. ASH 2022). Odronextamab was administered with steroid prophylaxis and step-up doses of 0.7/4/20 mg during C1, followed by 160 mg on Days 1, 8, and 15 of C2-4. After C4, odronextamab maintenance treatment continued at 320 mg every 2 weeks until disease progression or unacceptable toxicity. Pts who achieved a complete response (CR) that was durable for ≥9 months transitioned to dosing every 4 weeks. The final analysis was performed when all pts had the opportunity for ≥36 weeks of follow-up. The primary endpoint was objective response rate (ORR), assessed by independent central review (ICR) according to the Lugano classification. Key secondary endpoints included CR rate, duration of response (DoR), progression-free survival (PFS), overall survival (OS), and changes in scores of patient-reported outcomes. Minimal residual disease (MRD) was included as an exploratory endpoint. Results At the time of data cut-off (Jan 31, 2023) the DLBCL cohort was fully enrolled; 141 pts were evaluable for safety and 127 were evaluable for efficacy, with a median duration of follow-up of 26.2 months. In the safety-evaluable DLBCL population, median age was 66 years (range 24-88), 60% male, 80% Ann Arbor stage III-IV, 56% IPI score ≥3, and median prior lines of therapy was 2 (range 2-8). 17% of pts had transformed disease from indolent lymphoma and 5% had Richter's transformation; 12% were double-hit and 6% triple-hit. In total, 57% of pts were primary refractory and 66% were double refractory to an anti-CD20 antibody and an alkylator in any line of therapy. ORR and CR rate confirmed by ICR were 52% (66/127) and 31% (39/127), respectively, and were consistent across high-risk subgroups. Median DoR was 10.2 months (95% CI: 5.0-not estimable [NE]) and median duration of CR was 17.9 months (95% CI: 9.2-NE); the probability of maintaining CR for 24 months was 48%. Patient-reported outcomes were maintained or improved; of special note, patient-reported pain and emotional functioning scores improved from baseline during the course of treatment. MRD status at 12 weeks was highly predictive of PFS. Safety was generally consistent with previous reports. Treatment-related AEs led to odronextamab interruption/delay in 75 (53%) pts and discontinuation in 14 (10%) pts. The most common treatment-emergent AEs (>30% all grades) were CRS (55%), anemia (43%), and pyrexia (42%). With the optimized 0.7/4/20 mg step-up regimen (n=74), 98% of CRS events were Grade (Gr) 1/2, and only one Gr 3 CRS (confounded by pancreatitis) was reported. CRS events resolved with supportive measures; 26% of pts received tocilizumab for CRS management with the optimized regimen. No ICANS events were reported with the optimized step-up regimen. Gr ≥3 infections occurred in 52 (37%) pts (Gr 5, n=16 [11%]); COVID-19 infections were reported in 23 (16%) pts, which were Gr 5 in 6 (4%) pts. Conclusions Results of the final analysis of the ELM-2 study R/R DLBCL pt cohort confirm the highly encouraging clinical activity of odronextamab in a hard-to-treat pt population, including in pts with high-risk features. Responses were deep and durable with a 48% probability of maintaining CR for 2 years. The safety profile was generally consistent with earlier reports and CRS events were predominantly low grade and manageable. Importantly, continued treatment with odronextamab showed no detrimental effects on patient-reported outcomes. Odronextamab may be an important potential option in future management of R/R DLBCL, and these results support the continued investigation of odronextamab in Phase 3 trials. Updated data will be presented.

3-Year Analysis of ZUMA-12: A Phase 2 Study of Axicabtagene Ciloleucel (Axi-Cel) As First-Line Therapy in Patients with High-Risk Large B-Cell Lymphoma (LBCL)

Background: Axi-cel is an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy approved for the treatment of relapsed/refractory (R/R) LBCL. ZUMA-12 (NCT03761056) is a Phase 2, multicenter, single-arm study of axi-cel as part of first-line treatment in patients with high-risk LBCL. In the primary efficacy analysis (n=37; median follow-up of 15.9 months), axi-cel demonstrated a high rate of investigator-assessed complete response (CR; 78%; 95% CI, 62-90) and an 89% objective response rate (ORR; 95% CI, 75-97). Axi-cel also had a manageable safety profile, with no new safety signals observed in the first-line setting (Neelapu et al. Nat Med. 2022). Here, we report updated efficacy and safety outcomes from ZUMA-12 in all patients treated with axi-cel after a median follow-up of ≥40 months. Methods: Eligible adults had high-risk LBCL, with MYC and BCL2 and/or BCL6 rearrangements (double- or triple-hit histology) per investigator or an International Prognostic Index (IPI) score ≥3, plus a positive interim PET per Lugano classification (Deauville score 4/5) after 2 cycles of an anti-CD20 monoclonal antibody and anthracycline-containing regimen. Patients underwent leukapheresis, followed by lymphodepleting chemotherapy (cyclophosphamide and fludarabine) on Days -5, -4, and -3, and a single axi-cel infusion of 2×10 6 CAR T cells/kg on Day 0. Per investigator discretion, non-chemotherapy bridging could be administered. The primary endpoint was investigator-assessed CR rate per Lugano classification (Cheson et al. J Clin Oncol. 2014). Secondary endpoints included ORR, duration of response (DOR), event-free survival (EFS), progression-free survival (PFS), overall survival (OS), safety, and levels of CAR T cells in blood and cytokines in serum. Results: As of May 3, 2023, 42 patients were enrolled and 40 were treated with axi-cel, with a median follow-up of 40.9 months (range, 29.5-50.2). In total, 37 patients were evaluable for response (centrally confirmed double- or triple-hit histology or IPI score ≥3). The CR rate was 86% (95% CI, 71-95), and 92% (95% CI, 78-98) of patients had an objective response. Patients with centrally confirmed double- or triple-hit histology (n=10) had a CR rate of 90%. Responses were ongoing in 73% of response-evaluable patients at data cutoff. Medians for DOR, EFS, PFS, and OS were not reached. The 36-month estimates for DOR, EFS (Figure 1), PFS, and OS (Figure 2) were 82%, 73%, 75%, and 81%, respectively. All treated patients (n=40) experienced adverse events (AEs) of any grade and 88% of patients had grade ≥3 AEs. Similar to the primary analysis, the most common any-grade AEs were pyrexia (100%), headache (70%), and neutrophil count decreased (55%). No new cases of cytokine release syndrome (CRS) or neurologic events of any grade occurred since the prior data cut and all cases of CRS and neurologic events reported were resolved by data cutoff. Prolonged cytopenias of any grade (present Day ≥30 post-infusion) occurred in 9 patients (n=7 neutrophil count decreased) and were resolved by data cutoff. There were 8 deaths due to progressive disease (n=5) and other causes not related to axi-cel (1 COVID-19, 1 esophageal adenocarcinoma, 1 septic shock on Days 350, 535, and 287 post axi-cel infusion, respectively). Two of the 8 deaths (1 progressive disease and 1 esophageal adenocarcinoma) occurred after the primary analysis. Among treated patients, post-infusion CAR T-cell expansion by peak and area under the curve was 36.9 cells/µL and 368.0 cells/µL×days, respectively, in those with ongoing responses at data cutoff (n=17), 45.1 cells/µL and 413.4 cells/µL×days in those who relapsed (n=6), and 34.7 cells/µL and 566.8 cells/µL×days in non-responders (n=3). Conclusion: In this updated analysis of ZUMA-12 with a median follow-up of ≥40 months, axi-cel demonstrated a high rate of durable responses and no new safety signals. Axi-cel may benefit patients exposed to fewer prior therapies and those with high-risk LBCL, a population with high unmet need and poor outcomes after standard first-line chemoimmunotherapy.

Nex-T TM Cluster of Differentiation 19 (CD19) Chimeric Antigen Receptor (CAR) T-Cell Therapy BMS-986353 (CC-97540): Comparative Analysis of Baseline Patient Data from Trials in Systemic Lupus Erythematosus (SLE) and Relapsed/Refractory Large B-Cell Lymphoma (R/R LBCL) Related to Manufacturability and Potential Safety

Introduction: CAR T-cell therapy is currently being evaluated in non-oncologic autoimmune diseases (Mougiakakos D et al. N Engl J Med 2021; Müller F et al. Lancet 2023). In a cohort of patients (pts) with SLE, CD19 CAR T-cell therapy resulted in B-cell depletion and treatment-free, durable remission per Definitions of Remission In SLE (DORIS), suggesting that CD19 CAR T therapy may be feasible, well-tolerated, and effective for patients with SLE (Mackensen A et al. Nat Med 2022). Baseline traits associated with greater manufacturing success and lower toxicity profiles for CAR T have been identified in hematologic oncology (Mashadi-Hossein A et al. J Clin Oncol 2023; Rytlewski J et al. J Clin Oncol 2022) including age, bone marrow function, inflammatory state, and tumor burden. Here, we compared baseline traits in pts with active SLE versus R/R LBCL to predict the potential manufacturing success and toxicity profile for the ongoing phase 1 study to evaluate the investigational NEX-T TM CAR T-cell product BMS-986353 (CC-97540) in pts with severe, refractory SLE (NCT05869955). Methods: This post hoc analysis compared 42 quantitative baseline traits between pts with active SLE from PAISLEY (NCT03252587; Morand E et al. Arthritis Rheumatol 2023) and pts with R/R LBCL from TRANSCEND (NCT02631044; Abramson J et al. Lancet 2020). Baseline traits associated with improved manufacturing success and/or lower toxicity profile for CAR T in hematologic oncology were compared (Mashadi-Hossein A et al. J Clin Oncol 2023; Rytlewski J et al. J Clin Oncol 2022). A Wilcoxon rank-sum test was used to compare pt cohorts. Data are median (95% confidence interval). Results: This analysis included 363 pts with SLE and 256 pts with R/R LBCL. Of 42 baseline traits compared, 36 had nominal P values ≤ 0.05; 33 of those were ≤ 0.001. High baseline absolute lymphocyte count (ALC), platelets (PLT), and hemoglobin (Hgb) were previously associated with both improved manufacturing success and a lower toxicity profile for CAR T; pts with SLE had higher ALC, PLT, and Hgb vs R/R LBCL (ALC: 1.15 10 9/L [1.07-1.20 10 9/L] vs 0.10 10 9/L [0.10-0.13 10 9/L], P < 0.001, Figure 1A; PLT: 239 10 9/L [232-249 10 9/L] vs 144 10 9/L [129-154 10 9/L], P < 0.001; Hgb: 128 g/L [126-130 g/L] vs 98.0 g/L [95.0-100.0 g/L], P < 0.001), which is predictive of both improved manufacturing success and potentially lower toxicity. Young baseline age and high red blood cell (RBC) counts were previously associated with improved manufacturing success, and pts with SLE were younger and had higher RBC counts vs R/R LBCL (age: 40 years [38-41 years] vs 63 years [61-64 years], P < 0.001; RBCs: 4.30 10 12/L [4.20-4.40 10 12/L] vs 3.13 10 12/L [3.05-3.20 10 12/L], P < 0.001), predicting improved CAR T manufacturing success. Baseline traits reflecting tumor burden and/or bone marrow involvement that have been previously associated with higher toxicity, such as high C reactive protein (CRP; Figure 1B), high lactate dehydrogenase (LDH), and low hematocrit (Hct), were different between pts with SLE vs R/R LBCL (CRP: 1.92 mg/L [1.60-2.48 mg/L] vs 20.0 mg/L [15.5-31.8 mg/L], P < 0.001; LDH: 184 U/L [179-191 U/L] vs 282 U/L [251-317 U/L], P < 0.001; Hct: 39.0% [39.0-40.0%] vs 29.6% [28.7-30.5%], P < 0.001), and predict potentially lower toxicity. Conclusions: Comparison of baseline pt data from trials in SLE vs R/R LBCL suggests that pts with SLE have traits that predict improved manufacturing success and lower rates/severity of common CAR T-associated toxicities such as cytokine release syndrome (CRS) and neurological events. A key difference between cohorts is the potential for high tumor burden in R/R LBCL which has been previously associated with CAR T toxicity. Our results show marked differences between cohorts for tumor burden surrogate measures (CRP, LDH, Hct), bone marrow function, inflammatory state, and age which we hypothesize may potentially lead to improved CAR T manufacturing success and lower risk of CRS and/or neurological events for patients with autoimmune disorders vs R/R LBCL. Further research is needed to understand if CAR T-cell therapy may provide a promising treatment option for pts with SLE and other autoimmune conditions. The ongoing phase 1, multicenter, open-label study will evaluate the safety, feasibility, and preliminary efficacy of BMS-986353 (CC-97540) in patients with severe, refractory SLE. Study support: Bristol Myers Squibb

Excellent Safety Profile of a Low-Cost Novel Humanized CD19 CAR T-Cell Therapy, Actalycabtagene Autoleucel : Potential Impact on Access and Feasibility

Background: A high incidence of severe toxicities especially grade 3/4 immune effector cell-associated neurotoxicity syndrome (ICANS) and cytokine release syndrome (CRS), need for hospitalization, and the cost of supportive care is an hindrance to the implementation of CAR-T cell therapy for low and middle income countries (LMICs). To address these limitations, we designed a novel humanized CD19 CAR and demonstrated a favorable balance of efficacy to toxicity in the preclinical model and in the first-in-human Phase I study (Dwivedi et al. Mol Cancer Ther. 2021, Karulkar et al. ASH 2022). Here, we quantified the healthcare resource utilization (HCRU) and associated cost of clinical management of Actalycabtagene autoleucel (Actaly-cel) in India from an ongoing Phase I/II study in B-cell malignancies. Methods: This is a retrospective analysis of the HCRU costs of patients with r/r B-cell malignancies treated on Phase I/II study with Actaly-cel at 3 centers in India between June 2021 through July 2023. The key components of HCRUs are defined in Table 1 and were quantified from the electronic records from the time of enrolment till their last follow-up. Once enrolled, bridging therapy was allowed at investigator's discretion. After lymphodepletion (LD) with a fludarabine plus cyclophosphamide (FC) regimen for 3 days, patients received Actaly-cel at a target dose ≥ 5 million CAR-T cells/kg (upper limit; total 2 x10 9). The patients were monitored for toxicities particularly CRS, ICANS and cytopenias, as inpatient (non-HEPA filtered rooms) for at least a week. CRS and ICANS were graded as per ASTCT grading system and cytopenias as per CTCAE v5. Results: Total 59 patients were enrolled in this study and 47 patients received the infusion. Thirty seven patients (r/r lymphoma; n=28, r/r B-ALL; n=9) who completed 28 days post-infusion were evaluable for HCRU analysis. The median age was 37 years (16-71). The median follow-up of the cohort was 60 days (21-644); 19% (7/36) and 11% (4/36) patients completed 6 months and 12 months follow-up respectively. Among all patients (n=37) who received LD therapy, 46% of lymphoma patients received LD in the outpatient setting while 78% of B-ALL patients required hospitalization for LD. The median hospitalization period post Actaly-cel infusion was only 8 days (range: 7-17 days) in the lymphoma cohort, and 13 days (range: 7-19 days) for B-ALL patients. Importantly, none of the lymphoma patients required ICU admission, and only one B-ALL patient required ICU admission for management of adverse events. In the lymphoma cohort, 54% (15/28) of patients developed Grade 1/2 CRS and none had grade >/=3. A single dose of tocilizumab was given to 36% (10/28) of patients and only 4% (1/28) received tocilizumab plus corticosteroids. None of the patients required vasopressor support. Majority of B-ALL patients developed CRS. The incidence and severity of CRS was as follows: G1; 44% , G2; 11% and G3; 22%. There were no grade 4/5 CRS events. While 11% (1/9) of patients received a single dose of tocilizumab, 44% (4/9) received tocilizumab in combination with corticosteroids. Vasopressors were required in 22% of patients. None of the patients developed ICANS of any grade . Most patients (lymphoma and B-ALL) developed hematological toxicities(Table 1). The severity of Grade 3-4 was more prevalent in the B-ALL cohort. IVIG was administered to 25% of lymphoma and 22% of B-ALL patients. The induction and severity of the above toxicities were not dependent on the Actaly-cel dosage (median: 9 x 10 6 ;range: 2 x 10 6-21 x 10 6 CAR-T cells/kg). The projected production cost of Actaly-cel in the regional decentralized manufacturing model at the scale of 300 patients/year is ~15,000 USD per patient. The mean cost of HCRU for clinical management (until last follow-up) per patient was ~ 4,400 USD in an academic centre (lymphoma; ~4,000 USD, B-ALL; ~5,565 USD) and interestingly, only about 14% of these costs were incurred due to inpatient management (Figure 1). Conclusions: Actaly-cel was efficacious, with no incidence of ICANS and manageable CRS across a wide dose range. More importantly, this study reported low HCRUs due to negligible ICU admission and shorter duration of hospitalization, ensuring potential usage of Actaly-cel in outpatient settings, and ultimately improving the access and feasibility of CD19 CAR-T cell therapy in resource constrained settings such as LMICs.

Early and Consistent CRS Detection Using Wearable Device for Remote Patient Monitoring Following CAR-T Therapy in Relapsed/Refractory Multiple Myeloma (RRMM): Early Results of an Investigator-Initiated Trial

The administration of Chimeric Antigen Receptor T-cell (CAR-T) therapy for relapsed refractory multiple myeloma (RRMM) predominantly takes place in the inpatient setting to monitor for adverse effects like cytokine release syndrome (CRS) and neurotoxicity leading to increased healthcare utilization, infection risk and patient discomfort. Shifting the administration model to the outpatient setting may improve patient experience, optimize hospital bed utilization and decrease costs, but requires an objective and reliable method for CRS detection to monitor patients remotely and safely. The feasibility of using a wearable device for detecting CRS following CAR-T therapy in RRMM was compared to standard of care (SoC) nursing-recorded vital signs in this investigator initiated clinical trial (IIT). Patients wore a wearable device that collected continuous measures of temperature, pulse, respiratory rate, and O2 saturation in addition to SoC while receiving CAR-T therapy from the day infusion to discharge. Changes in vital signs captured by the device were analyzed based on 2 thresholds: (i) CRS timestamps were tagged in wearable data when pt's temperature breached a fixed threshold of 38 0C ( Tf) defined as fever by the American Society of Transplantation and Cellular Therapy (ASTCT), and (ii) when pt's temperature breached an individualized threshold of 2 standard deviations above their baseline temperature ( Ti) [see Figure 1]. Outcomes were time to first detection of CRS in wearable data vs. SoC. Wearable adherence was the duration pts wore the device over the total monitoring period. To date, 34 pts were screened, 28 enrolled (82.3% uptake), 1 was excluded from the dataset because of concurrent COVID-19, and 2 pts with CRS were excluded from time to detection comparison because of wearable adherence <50% during high-risk windows (defined as the time period where CRS is expected per known data for the CAR-T product). Max CRS grades were 1 (17 pts), 2 (1 pt), 3 (2 pts), and 4 (1 pt); 5 pts did not have clinical CRS. Patients wore the device for a median of 13 (12-15) days out of a median of 15.5 (14-17) days of inpatient admission for CAR-T infusion. Median individualized temperature threshold was 37.4 (37-37.6) C. Wearable adherence was 64 (51 - 77) % and 72 (57 - 87) % for the overall monitoring and high-risk periods, respectively. The wearable detected the initial CRS events at a median of 22 (-43 - 113.5) min earlier than SoC with Tf and a median of 184 (53 - 312) mins earlier than SoC with Ti method. In the no CRS subgroup, false CRS detection occurred in 1 pt with the Tf and 2 pts with the Ti method. Preliminary results suggest that time to CRS detection by the wearable device preceded SoC detection by a median of 103 minutes corroborated by both threshold methods. Temperature thresholds calibrated to the baseline temperature of individual patients facilitate earlier detection of CRS than fixed thresholds per clinical/ASTCT criteria. While the low false detection rate in is encouraging, these may also potentially be attributed to subclinical events. Both pts who had “false positive” triggers breached their individualized temperature thresholds via device readings while only recording low-grade temperatures that did not meet clinical CRS criteria per ASTCT, indicating possible capture of subclinical events. The study showcases the utility of continuous remote patient vital signs monitoring by wearable devices in efficiently capturing CRS, including subclinical events, earlier than SoC. Objective and reliable CRS monitoring may help safely transition workflows to outpatient CAR-T administration models. Analysis of trends in cytokine biomarkers for early CRS detection signal(s) is currently underway. Cytokine signals, alone and in combination with device data, are planned to be incorporated into machine learning models to build a CRS prediction index in future analyses. Figure 1: Snapshot in time of the continuous temperature data generated by the wearable device after CAR-T infusion showing capture of cytokine release syndrome. – Ti (solid line) represents the median baseline temperature of the patient over the entire duration of the data capture by the wearable device – Tf (dotted line) represents the temperature threshold of 38 0C, the clinical definition of fever as per ASTCT – Black diamond: clinical CRS event, when temperature >38 0C as recorded by nursing