Post Infusion Research Articles

Real-World Evidence in the United States (US) of the Impact of Bridging Therapy Prior to Axicabtagene Ciloleucel (Axi-Cel) for the Treatment of Relapsed or Refractory Large B-Cell Lymphoma (R/R LBCL)

Introduction: Axi-cel utilization expanded after demonstration of superior event-free survival in patients (pts) with early relapsed or primary refractory LBCL (Locke, et al. NEJM. 2022) and was reinforced by improved overall survival (OS) among these pts (Westin, et al. NEJM. 2023). Despite increased demand, limited data exist on the impact of bridging therapies (BT) on pt outcomes. Thus, BT use between leukapheresis and lymphodepletion (LD) is largely at the discretion of treating physicians. Here, we assessed the impact of BT on effectiveness and safety outcomes after axi-cel. Methods: Pts receiving axi-cel for 3L+ LBCL in the US between 2017-2020 were prospectively collected through the CIBMTR registry in a post-authorization safety study; data up to May 2023 were included. Effectiveness outcomes were overall response rate (ORR), complete response (CR) rate, duration of response (DOR), progression-free survival (PFS), and OS. Safety outcomes were cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) per ASTCT grading, non-relapse mortality (NRM), and other key adverse events. Propensity score-based inverse probability of treatment weighting (IPTW) was used in logistic and Cox regressions to account for potential confounding in BT use. For pts who had BT, effects of BT types and responses on outcomes were evaluated using conventional logistic and Cox regressions. Results: Of 1497 pts registered, 1307 had BT data available and were included (median follow-up, 36 mo). Overall, 430 pts (33%) received BT (median time from leukapheresis to LD, 23 days [IQR, 21-28]). Systemic therapy was used in 403 pts (31%), including 305 (23%) with chemotherapy (CT)-based BT (19% treated with CT + anti-CD20 monoclonal antibody [mAb; mainly rituximab] and 4% with CT only), and 98 (7%) with non-CT systemic therapy (Table). Radiotherapy (± systemic therapy) was used in 44 pts (3%). Pts with ≥3 lines of prior therapy (odds ratio [OR], 10.67 [95% CI, 7.17−15.87]) or mild hepatic impairment prior to infusion (OR, 1.64 [1.06−2.55]) were more likely to receive BT, while those with histologic transformation (OR, 0.69 [0.51−0.92]) or longer time from diagnosis to leukapheresis were less likely to receive BT. ORRs to axi-cel were 70% and 79% (CR rates 51% and 64%) for pts with or without BT, respectively. Unadjusted DOR, PFS, and OS at 3 years were 40%, 28%, and 37%, respectively, in pts with BT vs 49%, 39%, and 49%, respectively, in those without BT. After multivariate adjustment, no statistical significance was found between BT and any effectiveness outcome. Adjusted hazard ratios (HRs) for BT were 1.13 (95% CI, 0.94-1.36) for PFS and 1.11 (95% CI, 0.92-1.34) for OS, respectively (Figure). Most safety endpoints were consistent regardless of BT. Grade ≥3 CRS and ICANS occurred in 12% and 30% of pts, respectively, who received BT vs 10% and 24% of pts who did not. Use of BT was associated with more frequent prolonged neutropenia (OR, 2.24 [1.44-3.50]) and thrombocytopenia (OR, 2.33 [1.67-3.24]), but not associated with a higher rate of infections or NRM (Table). Among pts receiving BT, 74 (17%) had a CR or partial response to BT. Of them, median PFS and median OS post infusion were 12.7 mo (3.8-not estimable [NE]) and 48.7 mo (18.6-NE), respectively. Response to BT was associated with increased CR rate (OR, 2.00 [1.07-3.75]), PFS (HR, 0.69 [0.49-0.99]), and OS (HR, 0.59 [0.40-0.88]) and decreased any-grade ICANS (OR, 0.51 [0.29-0.92]). When different BT strategies were considered, effectiveness and most safety outcomes for CT + anti-CD20 mAb vs non-CT treatment were comparable without significant difference. CT + anti-CD20 mAb was associated with improved ORR (OR, 1.90 [1.00-3.60]), PFS (HR, 0.69 [0.49-0.98]), and OS (HR, 0.66 [0.46-0.95]) but increased any-grade CRS (OR, 2.16 [1.02-4.57]) vs CT only. CT use was associated with an increased risk of prolonged thrombocytopenia (41% vs 24% for pts receiving non-CT treatment; OR, 2.37 [1.39-4.02]). No significant association was found between use of radiotherapy as BT and any outcome. Conclusion: These US real-world findings suggest that the addition of BT prior to axi-cel is associated with more frequent prolonged cytopenias but does not impact effectiveness or other critical safety outcomes. Response to BT may prognosticate more favorable outcomes after axi-cel infusion. Further study is warranted to identify the optimal bridging regimen.

Innate Cell Engager (ICE®) AFM13 Combined with Preactivated and Expanded (P+E) Cord Blood (CB)-Derived Natural Killer (NK) Cells for Patients with Refractory CD30-Positive Lymphomas: Final Results

CONCLUSIONS Pts with refractory Hodgkin (HL) and other CD30+ lymphomas have few effective therapies available and targeted NK cell immunotherapy is an active area of research. Transfer of non-targeted NK cells has shown limited clinical benefit as target recognition of cancer cells by NK cells constitutes a barrier. The innate cell engager AFM13 is a first-in-class CD30/CD16A bispecific antibody construct that induces selective killing of CD30+ tumor cells by engaging and activating NK cells. As a single agent, AFM13 has limited clinical activity against HL, likely due to the reduced effector function of autologous NK cells in these pts, which provides the rationale for combining AFM13 with allogeneic NK cells. Our prior preclinical work identified a promising combination of CB-derived NK cells that were first IL-12/IL-15/IL-18-preactivated followed by ex vivo expansion (P+E) with engineered K562 feeder cells expressing membrane-bound IL-21, 4-1BBL and CD48 and exogenous IL-2, and subsequently complexed with AFM13 just before infusion; these cytokine-induced memory-like NK cells presented chimeric antigen receptor (CAR)-NK-like features and increased in vitro and in vivo antitumor activity compared to either non-AFM13-precomplexed P+E NK cells or to AFM13 alone (Kerbauy et al, Clin Cancer Res 2021). Building on this work we wished to study this CB NK-cell therapy in pts with refractory CD30+ lymphomas. This investigator-initiated single-center phase I-II trial (NCT04074746) evaluated the safety and activity of P+E AFM13-precomplexed CB NK cells followed by systemic AFM13. Pts ages 15-75 with CD30+ lymphomas refractory to brentuximab vedotin were enrolled. The goals were to identify the recommended phase 2 dose (RP2D) of NK cells, estimate the overall (ORR) and complete response (CR), event-free (EFS) and overall survival (OS) rates, and study NK cell activation and persistence. Each treatment cycle consisted of fludarabine/cyclophosphamide (days −5 to −3) followed by infusion (day 0) of the AFM13-precomplexed CB NK cells, cultured for 14 days as described above, and three weekly IV infusions of AFM13 (200 mg, days 7, 14 and 21). Two cycles were planned for pts 1-19 and up to 4 cycles from patient 20 on. Response was evaluated on day 28 of each cycle. Enrollment proceeded at 3 dose levels (DL) of 10 6, 10 7 and 10 8 NK/Kg, respectively. Each patient received the same NK dose in all cycles. Between 09/20-12/22 we enrolled 42 pts (37 HL, 5 NHL), pretreated with a median 7 lines, at DL1 (N=3), DL2 (N=3) and DL3 (N=36), with 1 (N=2), 2 (N=21), 3 (N=3) or 4 cycles (N=16). All had active progressive disease at enrollment and no bridging therapy was given. The cords used for each of the 117 cycles were selected without consideration for HLA match, which was 0/6 (N=53), 1/6 (N=46), 2/6 (N=14), 3/6 (N=3) and 4/6 (N=1). The product infused consisted of >94% NK cells (expanded >2,700 fold), with only 0.02% T cells. The NK cells were 96% viable, 91% bound to AFM13, and 97.6% CD16+. The products were infused fresh. There was 1 grade 2 infusion-related reaction (IRR) in 115 infusions of AFM13-NK (0.8%) and 27 IRR infusion related reactions in 350 infusions of AFM13 (7.7%) (1 G3, 26 G2). We saw no cases of CRS, ICANS or GVHD of any grade. DL3 (10 8 NK/Kg) was established as the RP2D. The ORR and CR were 92.8% and 66.7%, respectively (94.4% and 72.2%, respectively, in 36 pts treated at the RP2D). Nine pts had a response consolidated with SCT (5 allo, 4 auto). At median follow-up of 14 (6-34) months, the EFS/OS rates are 31%/76%; median EFS/OS are 8 months/not reached. No relapses were associated with antigen loss. In the subset of pts planned for 4 cycles at RP2D, 15 of 23 pts remained event free at 6 mo (4 pts with and 11 without SCT consolidation), for 6-month EFS/OS rates of 65%/83%. Overall, 8 of the 9 pts (89%) receiving a consolidation SCT are event free at 10 to 34 months. AFM-bound CB NK cells were detected in blood from day 1 post infusion for up to 3 weeks. Donor NK levels followed similar patterns after each cycle, which argues against a sensitization after the first NK infusion. CyTOF studies showed increased expression of AFM13 and activation markers in donor NK cells. We confirmed trafficking of AFM13-bound donor NK cells to tumor sites shortly after infusion. CB-derived cytokine-induced memory-like NK cells precomplexed with AFM13 have excellent tolerability and activity for pts with heavily pretreated and refractory CD30+ lymphoma.

Easix Indices Predict CRS and Overall Survival in Adult CAR-T Cell Recipients

Background: Immunotherapy with Chimeric Antigen Receptor T cells (CAR-Τ) is worldwide commercially available for refractory B cell malignancies, with continuously expanding indications.Given that cytokine release syndrome (CRS) and neurotoxicity (ICANS) are encountered in many CAR-T recipients both in trials and real-world setting, novel predictive and prognostic markers are highly needed. Aim: To this end, we hypothesized that EASIX (Endothelial Activation and Stress Index) and the most recently described modified EASIX (mEASIX) would be associated with severe CRS, ICANS and/or Overall Survival (OS) in the real-world setting. Methods: We collected data from consecutive adult patients (pts) from six transplant centers in Greece. Tisagenlecleucel and axicabtagene ciloleucel were administered since 2020, and brexucabtagene autoleucel since 2022. All pts received lymphodepleting therapy before CAR-T cell infusion with combination of cyclophosphamide and fludarabine. For patient monitoring as well as for prophylaxis and treatment of side effects, the EBMT and MD Anderson guidelines were adopted. EASIX (lactate dehydrogenase [LDH; U/L] x creatinine [mg/dL]/platelet [PLT] count; 10 9/L]) and mEASIX (which replaces creatinine with CRP [mg/dL]) were calculated before lymphodepletion (baseline), at day of infusion (0), and day 14 (14). The following variables were analyzed: age, gender, disease type and phase, product type, time from collection to product arrival and to infusion, progression-free (PFS) and overall survival (OS), laboratory markers at pre-specified time-points (LDH, creatinine, platelets, ferritin, CRP). Data cut-off date was end of June 2023, with at least 1 month of follow-up post infusion. Multivariate models were not performed due to multicollinearity issues. Results: Ninety pts, aged 49 (18-75) years, received commercial CAR-T cell products (33 tisagenlecleucel, 37 axicabtagene ciloleucel, 11 brexucabtagene autoleucel) for refractory/relapsed DLBCL (56), PMBCL (5), TFL (8), B-ALL (10), or MCL (11) after a median of 3 (1-9) previous lines of treatment including autologous (n=13) or allogeneic (n=7) transplantation. Severe (grade 3-4) CRS and ICANS were noted in 21% and 39%, respectively. Severe CRS was associated with mEASIXbaseline (p=0.025), and CRPbaseline (p=0.001), EASIX14 and m-EASIX14 (p<0.001). Both mEASIXbaseline and m-EASIX14 were able to predict severe CRS in ROC curve (AUC=0.768, p=0.032 and AUC=0.712, p=0.027). Severe ICANS did not correlate with EASIX indices, except for a trend towards statistically significant association with EASIX14 (p=0.054). On the other hand, severe ICANS was associated with increased LDH at baseline (p=0.001). With a median follow-up of 6.6 (1-42) months, 1-year PFS and OS were 33.2% and 62.5% respectively. Baseline values of ferritin and LDH, CRP values at all time-points, EASIX14 and mEASIX14 were associated with OS. Both EASIX indices predicted death in ROC curves. Similarly, EASIX14 was associated with PFS. Conclusions: This multicenter study, based on real-world experience with CAR-T cell therapy, confirms the predictive value of EASIX and mEASIX not only for life-threatening complications but also for survival outcomes. The implementation of EASIX may therefore aid in the selection of patients who are candidates for interventions to mitigate untoward sequelae of CAR-T therapy.

Long-Term Follow-up of Fully Human BCMA-Targeting CAR (CT103A) in Patients with Relapsed/Refractory Multiple Myeloma

Background: CT103A is a fully human chimeric antigen receptor T cell product targeting B cell maturation antigen (BCMA). Our previous reports showed a remarkable efficacy and safety of CT103A in patients with relapsed/refractory multiple myeloma (RRMM) at a median follow-up of 394 days. Here, we report the updated safety and efficacy profile in the long-term follow-up. Methods: This trial was a phase 1, single-arm, open-label study conducted in Tongji hospital in China. Eighteen consecutive patients with RRMM were enrolled, who received at least three lines of prior therapies that contain a proteasome inhibitor and an immunomodulatory agent. Lymphodepletion was performed using Fludarabine (30 mg/m 2) and cyclophosphamide (500 mg/m 2) for three consecutive days. CT103A was administered at 1, 3 and 6×10 6 CAR-positive T cells/kg in the dose-escalation phase, and 1×10 6 CAR-positive T cells/kg in the expansion cohort. From one-year post infusion, the response was evaluated every six months according to the IMWG 2016 consensus criteria. Minimal residual disease (MRD) was evaluated in the visits that bone marrow aspiration was performed. The minimum sensitivity of MRD was 10 -5 nucleated cells by standardized flow cytometry. All the adverse events (AEs) during the long-term follow-up were recorded and graded by CTCAE v5.0. Results: As of December 31, 2022, the median follow-up time after CAR T-cell infusion was 41.47 months (range, 0.63-51.33 months). Of the 18 patients assessable for efficacy, all patients (100%) achieved an overall response (partial remission or better) to CT103A. Among them, a total of 77.8% (14 of 18) of the patients finally achieved a CR or sCR, with enhanced responses over time. At the time of data-cutoff, nine patients (50%) were still alive, and seven patients (38.9%) remained sCR status with negative MRD. The median progression free survival (PFS) was 22.64 months and the median overall survival (OS) was 41.97 months. The rate of PFS and OS at 2 year was 50.0% and 72.2%, respectively. The patients with EMM had shorter survival than those without EMM. The median PFS was 12.02 months and the median OS was 28.52 months in patients with EMM, whereas the median PFS was 27.92 months and the median OS was 41.97 months in patients without EMM. During the long-term follow-up, the occurrence of AEs gradually reduced over time. The most common late adverse events occurring 8 weeks after CAR T-cell infusion were hematologic toxicities. Leukopenia and neutropenia could be observed in 11 patients (61.1%). After 8 weeks, the adverse events were mainly infections. 26 infectious events were recorded in 11 patients (61.1%) beyond 8 weeks, including nine events judged as severe AE (sAE) in 6 patients (33.3%). Five infectious events in five patients (27.8%) occurred after one year. Severe infections led to the death of 4 patients. The recovery of B cells and globulin were observed in 5 and 15 patients, respectively. But for the seven alive patients with sCR, only two of them had B cell recovered. The median CAR transgene persistence was 419 days. To the cutoff date, CAR transgenes were detectable in seven (38.9%) patients, six of these patients were in sCR state. Conclusion: The updated data from the long-term follow-up of CT103A demonstrated a durable clinical benefit for RRMM patients, based on the sustained existence of fully human CAR-T cells. In addition, the favorable safety profile strengthens the prospect of clinical application of CT103A.

Health-Related Quality of Life in Adults with Hemophilia B after Receiving Gene Therapy with Fidanacogene Elaparvovec

Introduction : The burden of the management and clinical sequelae of hemophilia B (HB) negatively impacts health-related quality of life (HRQoL), including chronic pain and mental health. Fidanacogene elaparvovec (PF-06838435, formerly SPK-9001) is an adeno-associated virus-based gene therapy vector transferring the high activity variant of human factor IX (FIX), FIX-R338L, aimed at enabling endogenous FIX expression in individuals with hemophilia B. We present descriptive data on the impact on HRQoL for participants in the fidanacogene elaparvovec phase 1/2a study. Methods : Fifteen participants with moderately severe to severe hemophilia B (FIX activity ≤2%) received a single infusion of fidanacogene elaparvovec 5e11 vg/kg as part of a phase 1/2a study (NCT02484092). The study was 52 weeks in duration, after which participants were eligible to enroll in a long-term follow-up (LTFU) study for up to 5 years (NCT03307980). All 15 participants completed the phase 1/2a study and 14 subsequently enrolled in the LTFU study (1 participant declined participation). Participants in both studies completed patient-reported outcome (PRO) HRQoL assessments, including the Haemophilia Quality of Life Questionnaire for Adults (Haem-A-QoL), the visual analog scale of the EQ-5D (EQ-VAS), and the Change in Level of Activity questionnaire, every 6 months through Week 156 post infusion and then once annually during the LTFU study. The Haem-A-QoL questionnaire consists of 46 items pertaining to 10 domains to assess HRQoL, and domains scores and the Total Score ranging from 0-100 based on the individual items (high scores indicate high impairment in HRQoL). In the EQ-VAS, participants rate their current health state for endpoints of 100 (best imaginable health) to 0 (worst imaginable health). In the Change in Level of Activity questionnaire, participants assess whether they have been doing more/fewer/the same amount or intensity of physical activities in the past month. The data cutoff date was August 2, 2022. Results : For 14 participants (aged 20 to 63 years), the mean (SD) age at entry to the LTFU study was 42 (13.7) years, body mass index was 26.4 (4.4) kg/m 2, and 85.7% were White. Of the 14 participants, 13 had HRQoL data available through Week 156; beyond this time point, there were 10 or fewer participants with both post- and pre-vector infusion (baseline) values. For the Haem-A-QoL assessment, the mean (SD) Total Score at Week 156 (n=12) decreased by 15.2 (10.3) from pre-vector infusion, indicating an improvement in HRQoL ( Fig. 1). A 7-point reduction in the total score has been shown to be clinically meaningful in previous studies (Von Mackensen S et al, Haemophilia 2020;26:1019-30; Wyrwich KW et al, Haemophilia 2015;21:578-84). Of the 12 participants with data at Week 156, 8 had Total Score decreases of 7 or more at each visit through Week 156. Similarly, participant scores for each individual domain decreased over time (implying an improvement in HRQoL) from pre-vector infusion in all instances except for the Dealing with Hemophilia domain ( Fig. 1). Mean EQ-VAS scores were above mean baseline score and were consistently greater than baseline by 7 to 8 points during Year 2 onward, suggesting an improvement in overall health status. At Week 156, the EQ-VAS score increased from baseline by mean (SD) 7.2 (6.2): baseline 83.7 (7.3), n=13; Week 156 91.5 (5.4), n=12. An EQ-VAS score change of 7 points has been shown to be clinically meaningful (Pickard AS et al. Health Qual Life Outcomes 2007;21:5:70). Responses in the Change in Level of Activity questionnaire showed that a greater proportion of participants at each visit (n=12-14) reported doing the same or more intensive physical activities up to Week 156 than reported at baseline ( Fig. 2). No participant reported a reduction in the amount or intensity of physical activities at Week 156 (n=13) ( Fig. 2). Conclusion : HRQoL improvements after gene therapy are an indicator that fidanacogene elaparvovec can reduce the burden associated with hemophilia. PRO assessments will be a part of BENEGENE-2, an ongoing pivotal phase 3 study to demonstrate the efficacy of fidanacogene elaparvovec and will provide additional insights via the analyses of secondary endpoints into HRQoL benefits for participants with HB following gene therapy with fidanacogene elaparvovec.

IL-10 plus the EASIX score predict bleeding events after anti-CD19 CAR T-cell therapy.

Chimeric antigen receptor (CAR) T-cell-associated coagulopathy can cause bleeding events. To explore risk factors for hemorrhage after CAR T-cell therapy, we retrospectively analyzed routine indicators in 56 patients with non-Hodgkin lymphoma and B-cell acute lymphoblastic leukemia who received anti-CD19 CAR T-cell therapy. Disturbance of coagulation occurred mainly within one month post infusion, especially on day 7 and 14. The cumulative incidence of bleeding events within one month was 32.8%, with the median onset of 7 (range, 0-28) days. All bleeding events were grade 1-3. Patients who experienced bleeding events within one month had longer prothrombin time, higher IL-6, higher IL-10, and lower platelets before lymphodepletion. There were also correlations among coagulation-, inflammatory-, and tumor burden-related markers. Multi-variate analysis showed IL-10 (> 7.98 pg/mL; adjusted odds ratio [OR], 13.84; 95% confidence interval [CI], 2.03-94.36; P = 0.007) and the endothelial activation and stress index (EASIX, defined as dehydrogenase [U/L] × creatinine [mg/dL] / platelets [×109 cells/L]; >7.65; adjusted OR, 7.06; 95% CI, 1.03-48.23; P = 0.046) were significant risk factors for bleeding events. IL-10 plus the EASIX defined three risk groups for bleeding events with cumulative incidence of 100% (hazard ratio [HR], 14.47; 95% CI, 2.78-75.29; P < 0.0001), 38.5% (HR, 3.68; 95% CI, 0.82-16.67; P = 0.089), and 11.8% (reference), respectively. Future studies are needed to verify the risk assessment models for bleeding events after CAR T-cell treatment in larger cohorts.

Does the peroral chromium administration in young Hariana calves reduce the risk of calf diarrhea by ameliorating insulin response, lactose intolerance, antioxidant status, and immune response?

BackgroundThe reduction in insulin sensitivity during rumen development may predispose dairy calves towards lactose intolerance, which could be the reason behind neonatal calf diarrhea (NCD). Chromium (Cr) results in a range of effects when fed to ruminants, but most studies have shown improved insulin sensitivity. The aim of this study was to determine the effect of Cr supplementation on insulin sensitivity, lactose intolerance, diarrhoea and antioxidant, and immune response in young Hariana calves. MethodsA total of 20 milk-fed Hariana calves were randomly assigned to 1 of 2 treatments, each consisted of 10 calves: (1) a control group without supplemental Cr and (2) a 0.15 mg Cr as Cr-picolinate (CrPic)/kg BW0.75 supplemented group (Cr0.15). ResultsA more rapid glucose disappearance with unaltered insulin kinetics during intravenous glucose tolerance test (IVGTT) and oral lactose tolerance test (OLTT) indicates greater insulin sensitivity in Cr supplemented calves. Better insulin sensitivity in Cr supplemented calves was further confirmed by higher values of the quantitative insulin sensitivity check index (QUICKI), revised quantitative insulin sensitivity check index (RQUICKI) and insulin receptor substrate-1 (IRS-1) and lower (P < 0.05) values of homeostasis model assessment-insulin resistance (HOMA-IR) and glucose-to-insulin ratio in Cr supplemented calves during IVGTT. Cr supplementation resulted in a lower (P < 0.05) serum cortisol concentration, whereas serum non-esterified fatty acid (NEFA) concentrations during IVGTT did not differ among the groups. The rise in serum glucose concentrations within 2 h post lactose infusion during OLTT peaked at more than twice the basal glucose concentration, therefore calves were not considered as lactose intolerant. Within monthly blood samples, concentrations of serum insulin were similar among treatments, whereas the Cr supplemented group had lower (P < 0.05) serum glucose concentration and glucose-to-insulin ratio compared with the control group. No treatment differences were detected in the biomarkers of antioxidant status and immunity. Serum Cr concentrations were higher (P < 0.05) in Cr supplemented calves while concentrations of other studied minerals were remained unaltered. The incidence, duration of diarrhea, and faecal score were better (P < 0.05) in calves fed on Cr supplemented diet whereas, no treatment effect was observed on average daily gain (ADG). During the study period, no calves died, and no calves were found to have pneumonia, navel or joint disease. ConclusionFeeding a Cr-supplemented diet improved insulin sensitivity and reduced the risk of diarrhoea in milk-fed young calves, but had no or minimal effects on lactose intolerance, antioxidant status, immune response, and growth performance.

281 Side-effects associated with IV Zoledronic Acid infusion in patients with osteoporosis

Abstract Background Osteoporosis is a common condition affecting bone, leading to fragility and fractures. Oral bisphosphonates are the first line treatment for osteoporosis reducing vertebral, hip and non-vertebral fractures. However poor compliance and Gastro-Intestinal (GI) intolerance result in poor persistence. Intravenous Zoledronic Acid (IV ZA) is an effective alternative therapy, improving compliance and tolerability. Side effects have been reported such as fever, flu-like symptoms, myalgia, arthralgia, headache, uveitis, iritis and hypocalcaemia. Methods This prospective observational study was carried out in a dedicated Bone Health Service. Patients diagnosed with osteoporosis were assessed by the Bone Health team regarding suitability for IV ZA. Infusions were administered in a nurse-led IV ZA clinic. Pre and 1-week post infusion bloods including Renal, Liver and Bone profile, Parathyroid hormone, Vitamin D and bone markers- Osteocalcin, CTX, PINP were taken. Side effects post infusion were recorded. Results N = 189. 161:28 female to male ratio. Age range 32-90 years, median 61 years. All diagnosed with osteoporosis in hip and/or spine. Forty-three percent were bisphosphonate naïve. 51 (27%) attended GP for post infusion bloods while 7 patients received infusion while inpatients. 29% of those returning to clinic for post infusion bloods reported side effects. Treatment naïve and treatment experienced reported similar rate of side effect 21%/20% respectively. Most common side effects include flu-like symptoms (31%) with fatigue/tiredness/generalised aches and pains/GI upset 16% respectively. 10% reported headaches while 5% experienced sore/swollen eyes. Rash, swollen joints and pre-syncope experienced by 3% respectively. Symptoms resolved after 24-48 hrs. Conclusion IV ZA is a well-established treatment for osteoporosis particularly for patients intolerant or poorly compliant with oral bisphosphonate therapy and an accepted treatment to close-off Denosumab. According to our study IV ZA is well tolerated with self-limiting side effects. However, pre infusion screening is essential to deem suitability.

Development of a rabbit human glioblastoma model for testing of endovascular selective intra-arterial infusion (ESIA) of novel stem cell-based therapeutics.

Endovascular selective intra-arterial (ESIA) infusion of cellular oncotherapeutics is a rapidly evolving strategy for treating glioblastoma. Evaluation of ESIA infusion requires a unique animal model. Our goal was to create a rabbit human GBM model to test IA infusions of cellular therapies and to test its usefulness by employing clinical-grade microcatheters and infusion methods to deliver mesenchymal stem cells loaded with an oncolytic adenovirus, Delta-24-RGD (MSC-D24). Rabbits were immunosuppressed with mycophenolate mofetil, dexamethasone, and tacrolimus. They underwent stereotactic xenoimplantation of human GBM cell lines (U87, MDA-GSC-17, and MDA-GSC-8-11) into the right frontal lobe. Tumor formation was confirmed on magnetic resonance imaging, histologic, and immunohistochemistry analysis. Selective microcatheter infusion of MSC-D24 was performed via the ipsilateral internal carotid artery to assess model utility and the efficacy and safety of this approach. Twenty-five rabbits were implanted (18 with U87, 2 MDA-GSC-17, and 5 MDA-GSC-8-11). Tumors formed in 68% of rabbits (77.8% for U87, 50.0% for MDA-GSC-17, and 40.0% for MDA-GSC-8-11). On MRI, the tumors were hyperintense on T2-weighted image with variable enhancement (evidence of blood brain barrier breakdown). Histologically, tumors showed phenotypic traits of human GBM including varying levels of vascularity. ESIA infusion into the distal internal carotid artery of 2 ml of MSCs-D24 (107 cells) was safe in the model. Examination of post infusion specimens documented that MSCs-D24 homed to the implanted tumor at 24 hours. The intracranial immunosuppressed rabbit human GBM model allows testing of ESIA infusion of novel therapeutics (eg, MSC-D24) in a clinically relevant fashion.

Development of a Multiscale Mechanistic Modelling Framework Integrating Differential Cellular Kinetics of CAR-T Cell Subsets and Immunophenotypes in Cancer Patients.

Chimeric antigen receptor (CAR) T-cell subsets and immunophenotypic composition of the pre-infusion product, as well as their longitudinal changes following infusion, are expected to affect CAR-T cell expansion, persistence, and clinical outcomes. Herein, we sequentially evolved our previously described cellular kinetic-pharmacodynamic (CK-PD) model to incorporate CAR-T cell product-associated attributes by utilizing published preclinical and clinical datasets from two affinity variants (FMC63 and CAT19 scFv) anti-CD19 CAR-T cells. In step 1, a unified cell-level PD model was used to simultaneously characterize the in vitro killing datasets of two CAR-Ts against CD19+ cell lines at varying effector: target (E: T) ratios. In step 2, an augmented CK-PD model for anti-CD19 CAR-Ts was developed, by integrating CK dataset(s) from two bioanalytical measurements (qPCR and flow cytometry) in cancer patients. The model described the differential in vivo expansion properties of CAR-T cell subsets. The estimated expansion rate constant was ~1.12-fold higher for CAR+CD8+ cells in comparison to CAR+CD4+ T cells. In step 3, the model was extended to characterize the disposition of four Immunophenotypic populations of CAR-T cells, including stem-cell memory (TSCM ), central memory (TCM ), effector memory (TEM ) and effector (TEFF ) cells. The model adequately characterized the longitudinal changes in immunophenotypes post anti-CD19 CAR-T cell infusion in acute lymphocytic leukemia paediatric patients. Polyclonality in the pre-infusion product was identified as a categorical covariate influencing differentiation of immunophenotypes. In the future, this model could be leveraged a priori towards optimizing the composition of CAR-T cell infusion product, and further understand the CK-PD relationship in patients.

Monitoring of Sotrovimab-Levels as Pre-Exposure Prophylaxis in Kidney Transplant Recipients Not Responding to SARS-CoV-2 Vaccines.

Background Sotrovimab, a monoclonal antibody against SARS-CoV-2, is used as a pre-exposition prophylaxis (PrEP) against COVID-19, but monitoring strategies using routine test systems have not been defined. Methods Twenty kidney transplant recipients without antibodies after vaccination received 500 mg Sotrovimab. Antibody levels were quantified over eight weeks using live-virus neutralization (BA1 and BA2), antibody binding assays (TrimericS, Elecsys, QuantiVAC) and surrogate virus neutralization tests (sVNTs; TECOmedical, cPass and NeutraLISA). Results Sotrovimab neutralized both Omicron subvariants (BA1 NT titer 90 (+-50) > BA2 NT titer 33 (+-15) one hour post infusion). Sotrovimab was measurable on all used immunoassays, although a prior 1:100 dilution was necessary for Elecsys due to a presumed prozone effect. The best correlation with live-virus neutralization titers was found for QuantiVAC and TrimericS, with a respective R2 of 0.65/0.59 and 0.76/0.57 against BA1/BA2. Elecsys showed an R2 of 0.56/0.54 for BA1/BA2, respectively. sVNT values increased after infusion but had only a poor correlation with live-virus neutralization titers (TECOmedical and cPass) or did not reach positivity thresholds (NeutraLISA). Conclusion Antibody measurements by the used immunoassays showed differences in antibody levels and only a limited correlation with neutralization capacity. We do not recommend sVNTs for monitoring SARS-CoV-2 neutralization by Sotrovimab.

Onasemnogene Abeparvovec: Post-infusion Efficacy and Safety in Patients With Spinal Muscular Atrophy (SMA)-A Fondazione Policlinico Gemelli IRCCS Experience.

Objective: The term Spinal Muscular Atrophy (SMA) identifies a group of genetic disorders affecting spinal motor neurons. It is caused by the loss of the SMN1 gene, resulting in degeneration of spinal alpha motor neurons and muscle atrophy. This study is focused on innovative gene therapies with onasemnogene abeparvovec approved in Italy in March 2021 with full reimbursement by the National Health Service. The objective pursued is verify, by means of the CHOP-INTEND scores obtained, whether therapy with onasemnogene abeparvovec led to an improvement in the clinical picture of the treated subjects and any adverse reactions that occurred. Methods: this study was conducted by evaluating the scores in the different re-evaluations of individual patients treated in our hospital (Fondazione Policlinico Universitario Agostino Gemelli IRCCS - Rome) and comparing them with the results of the CL-303 study described in SPC (Summary of Product Characteristics). The data were extracted from the patients' clinical records on the AIFA (Agenzia Italiana del Farmaco - Italian Medicines Agency) registries, also collecting information on any post-infusion ADRs. Everything was then represented graphically to have a clear comparison with the data from the study registered for drug approval. Results: from the data obtained, 7 out of 8 patients improved their health status post infusion with, in some cases, a significant increase in score. Conclusions: this result allows us to understand how crucial it is to start treatment as soon as possible after the diagnosis of the condition as the greatest improvements were seen in subjects who received treatment within 2 months of birth.

Expanded clinical-grade NK cells exhibit stronger effects than primary NK cells against HCMV infection.

Cytomegalovirus (CMV) reactivation remains a common complication and leads to high mortality in patients who undergo allogeneic hematopoietic stem cell transplantation (allo-HSCT). Early natural killer (NK) cell reconstitution may protect against the development of human CMV (HCMV) infection post-HSCT. Our previous data showed that ex vivo mbIL21/4-1BBL-expanded NK cells exhibited high cytotoxicity against leukemia cells. Nevertheless, whether expanded NK cells have stronger anti-HCMV function is unknown. Herein, we compared the anti-HCMV functions of ex vivo expanded NK cells and primary NK cells. Expanded NK cells showed higher expression of activating receptors, chemokine receptors and adhesion molecules; stronger cytotoxicity against HCMV-infected fibroblasts; and better inhibition of HCMV propagation in vitro than primary NK cells. In HCMV-infected humanized mice, expanded NK cell infusion resulted in higher NK cell persistence and more effective tissue HCMV elimination than primary NK cell infusion. A clinical cohort of 20 post-HSCT patients who underwent adoptive NK cell infusion had a significantly lower cumulative incidence of HCMV infection (HR = 0.54, 95% CI = 0.32-0.93, p = 0.042) and refractory HCMV infection (HR = 0.34, 95% CI = 0.18-0.65, p = 0.009) than controls and better NK cell reconstitution on day 30 post NK cell infusion. In conclusion, expanded NK cells exhibit stronger effects than primary NK cells against HCMV infection both in vivo and in vitro.

Safety and early efficacy results of phase 1 study of affinity tuned and trackable AIC100 CAR T cells in ICAM-1 positive relapsed and/or refractory advanced poorly differentiated and anaplastic thyroid cancers.

6095 Background: ICAM-1, a cell surface glycoprotein, is overexpressed in most ATC and PDTC. AIC100 is a 3rd-generation CAR T cell with micromolar affinity to ICAM-1, tuned lower than most CARs used to date in pre-/clinical studies. Affinity tuned AIC100 are expected to selectively bind and kill tumor cells while safely sparing healthy cells. AIC100 also co-expresses somatostatin receptor 2 (SSTR2), which enables in vivo monitoring of AIC100 distribution and expansion by DOTATATE PET/CT scan. Methods: The objectives of this phase 1 dose escalation study are to assess the safety, preliminary efficacy and to determine RP2D of AIC100 in patients with ICAM-1+ relapsed/refractory PDTC or ATC. 3 dose levels (DL) are being explored-DL1 at 1x 107, DL2 at 1 x 108 and DL3 at 5 x 108 AIC100. AIC100 is received as a single infusion two days after completing lymphodepletion with Fludarabine/Cyclophosphamide. FDG and DOTATATE PET/CT scans are used to assess response and to track AIC100 in vivo, respectively. Response is assessed by RECIST1.1, starting at end of treatment (day 42 post AIC100). AIC100 is manufactured using AffyImmune’s Tune and Track CAR T cell platform. Results: As of Feb 14, 2023, 6 pts (4 ATC; 2 PDTC) with a median age of 59.5 yrs (48-70) were infused with AIC100, 3 each in DL 1 and 2. AIC100 was successfully manufactured for all patients and all infusion products met target transduction efficiency. No serious adverse events or DLTs were reported. Two patients had grade 1 CRS. No ICANs was reported. In 3 evaluable patients in DL1, 1 patient had stable disease with decreased FDG activity in PET that correlated with increased activity in the DOATATE scan. From the 3 pts infused in the DL2, one is evaluable for efficacy at day 42. This is a patient with relapsed ATC who achieved PR with 42% reduction in target tumor lesion and remains in PR at 3 mths. The target lesion in this patient showed increased DOTATE avidity at d14 post AIC100 infusion. This was followed by decreased FDG and DOTATE avidity at d42 post AIC100 infusion, concomitant with decreased size, suggesting biological activity 42 days after CAR T infusion. Evaluation of CAR transgene demonstrated transient peripheral blood CAR T cell expansion. The second patient couldn’t be assessed due to early withdrawal for disease-related toxicity. The 3rd patient in DL2 remains in the DLT period, pending efficacy evaluation. Conclusions: AIC100 demonstrated an excellent safety profile in DL1/DL2 treated patients with ATC and PDTC with no DLTs observed. The objective and relatively durable partial response in the first evaluable patient in the DL2, a patient with metastatic ATC who failed multiple lines of therapy, is unprecedented and very encouraging. Further investigations of AIC100 are ongoing at DL2 and DL3 to determine the RP2D. Clinical trial information: NCT04420754 .

17th International Conference on Malignant Lymphoma, Palazzo dei Congressi, Lugano, Switzerland, 13 - 17 June, 2023.

Off-the-shelf allogeneic T-cell therapies face the major challenges of graft-versus-host disease (GVHD) and graft rejection mediated by host and recipient alloreactive T cells, respectively. To address GVHD, we are using Epstein-Barr Virus-specific T cells (EBVST), which are virus specific rather than allo-specific and have not produced GVHD in over 300 allogeneic recipients. To prevent graft rejection, we modified the EBVST with a chimeric antigen receptor (CAR) targeting CD30, an antigen that is upregulated on allo-activated T-cells, which will consequently become targets for CD30.CAR EBVST. Hence, CD30.CAR EBVST can kill both CD30+ lymphoma cells and alloreactive T cells through their CAR, and may be boosted in vivo in EBV+ recipients via their native TCR. We are evaluating this approach in a phase 1 trial (NCT04288726) in patients with CD30+ lymphoma. We generated a bank of 7 CD30.CAR EBVST products by stimulating PBMC from healthy donors with overlapping EBV peptide mixtures followed by retroviral transduction with a 2nd generation, CD28-containing CD30.CAR. We have treated 16 patients (median age 36, range 22–53) with relapsed or refractory HL. Patients had undergone a median of 5 (range 3–7) prior lines of treatment. Escalating doses of 4 × 107 − 8 × 108 (DL1–4) CD30.CAR EBVST were infused after lymphodepletion. The frequency of CD30.CAR EBVST was measured by real time qPCR for the transgene in blood. Changes in the frequency of T-cells responding to EBV or tumor-associated antigens (epitope spreading) were measured by IFNɣ ELISpots. Clinical responses were assessed per Lugano criteria by PET/CT scans performed 4–8 wks post infusion. CD30.CAR EBVST were well tolerated, with no GVHD and only two patients having reversible grade 4 cytopenia. Five patients at DL3–4 had grade 1 cytokine release syndrome (CRS), but all resolved without treatment. Of the 16 patients treated, 6 had partial responses (PR) and 6/13 patients at DL2–4 had complete responses (CR), giving an overall objective response rate (ORR) of 75%. Despite these remarkable responses, qPCR for the CD30.CAR transgene showed near background levels by wk 1 post infusion. Although this could mean that CAR-T are quickly eliminated by alloreactive T-cells, additional infusions from the same donor product into the same patient can be associated with response (Figure 1); an alloreactive response would be anticipated to be amplified after each infusion and preclude additional responses. We are therefore analyzing tumor biopsy samples to determine the presence of CD30.CAR EBVST at tumor sites and characterize their phenotype for functionality. The research was funded by: Leukemia and Lymphoma Society SCOR (Heslop) and Tessa Therapeutics (Rooney/Ramos) through a grant to Baylor College of Medicine. Keywords: cellular therapies, Hodgkin lymphoma Conflicts of interests pertinent to the abstract C. A. Ramos Consultant or advisory role: Novartis, Genentech, CRISPR Therapeutics Research funding: Tessa Therapeutics, Athenex Therapeutics Other remuneration: Royalties: Tessa Therapeutics D. H. Quach Research funding: Tessa Therapeutics P. D. Lulla Research funding: Marker Therapeutics, Allovir R. H. Rouce Consultant or advisory role: Pfizer, Novartis Honoraria: Novartis, Medline Plus Research funding: Tessa Therapeutics B. J. Grilley Consultant or advisory role: Allovir, Marker Therapeutics, Tessa Therapeutics, Lokon Pharma, March Bio and Proxima Clinical Research Stock ownership: Allovir, QBRegulatory LLC N. Lapteva Consultant or advisory role: Tessa Therapeutics Research funding: Tessa Therapeutics M. K. Brenner Employment or leadership position: Founder Member Marker Therapeutics Consultant or advisory role: Tessa Therapeutics, Marker Therapeutics, Allogene, Walking Fish, Athenex, Turnstone Biologics, Posedia, Tscan, Bluebird Bio, Adaptimmune Therapeutics, Adintus, Onkimure, Triumvira Immunologics, Bellicum Pharmaceuticals, Memgen LLC, Brooklyn Immunotherapeutics, Coya, Astrazeneca Pharmaceuticals Stock ownership: Allovir, Marker Therapeutics, Tessa Therapeutics, Turnstone, Bluebird Bio, Allogene, Walking Fish, AlloVir, Tessa, Tscan Other remuneration: Royalties: Takeda, Bellicum, Marker Therapeutics H. E. Heslop Consultant or advisory role: Gilead Biosciences, Novartis, Tessa Therapeutics, Marker Therapeutics, Kiadis, PACT Pharma, Mesoblast, Ankyra Therapeutics Stock ownership: Allovir, Marker Therapeutics, Fresh Wind Biotechnologies, CoRegen Inc. Research funding: Tessa Therapeutics, Athenex Therapeutics C. M. Rooney Consultant or advisory role: Tessa Therapeutics, Marker Therapeutics, Cell Genix Stock ownership: Allovir, Marker Therapeutics Research funding: Tessa Therapeutics Other remuneration: Royalties: Takeda, Marker, Allovir, Bellicum

PHASE‐2 FIRST‐IN‐INDIA INDUSTRY STUDY OF VARNIMCABTAGENE AUTOLEUCEL (IMN‐003A) IN RELAPSED REFRACTORY B CELL MALIGNANCIES: IMAGINE STUDY B‐NHL SUBANALYSIS

Introduction: Varnimcabtagene autoleucel (IMN-003A) is an autologous CD19 directed CAR-T with 4-1BB co-stim domain and A3B1 binder, a non-FMC63 murine scFv, manufactured in India for phase 2 study in patients (pts) with relapsed / refractory (r/r) B cell malignancies (CTRI/2022/03/041162). Target dose (B-ALL: 1 × 106 CAR+ cells/kg; B-NHL: 5 × 106 CAR+ cells/kg) was infused as 3 fractions (10%, 30%, 60%) after Flu-Cy lymphodepletion. B-NHL subanalysis is presented here. Methods: Pts ≥ 18 yrs with r/r B-NHL, measurable disease, ≥1 prior regimen and ECOG 0-1 were eligible. IMN-003A persistence was evaluated by ddPCR. Manufacturing was in CliniMACS Prodigy. CAR-T % transduction and T cell subsets were analyzed by flow. Primary objectives were overall response rate (ORR: CR + PR; IWG criteria) at day +90, and occurrence of adverse events. Results: Of 23 pts in study, 11 pts with B-NHL (median 53 yrs, range 31–66) underwent apheresis with 100% manufacturing success (median time 15d; range 11–27). Two needed second apheresis. Mean % transduction was 28.27% (range 8.50–51.07) with median transgene copies / genome of 2.36 (range 0.76–4.16). Mean CD4/CD8 ratio was 0.31 (apheresis); 0.62 (final product FP); 2.05 (Day 0) and 0.23 (Day 90) with reversal post infusion. Mean proportion of naïve cells (CCR7+ RA+) was >35% in FP (Fig 1A). Median Product Doubling time was 1.03d (range 0.88–2.12) and Apheresis to Infusion time was 30d (range 21–95). Max IMN-003A expansion (Tmax) was at median 10d (range 7–21) with median Cmax 122,029 CAR copies / μg gDNA (range 24,624–284,498). IMN-003A persistence was 100% at D+28 and 40% at D+90 (range 28–NR) with concurrent B cell aplasia (Fig 1B) range 90–NR. CD4+ T cell count recovery (>200/μL) was seen at median of 24.5 days (range 7- 42) post infusion. Of 9 pts infused, 4 (44.4%) needed bridging therapy (patient characteristics in Figure 1D). Median follow-up was 99 days (range 58–226). Overall response rate (ORR) was 88.8% at D+28 and 71.4% at D+90. Median time to first response was 28 days. Median progression-free survival (PFS) and overall survival (OS) were not reached (Figure 1C). AESIs reported were CRS (Grade [G] 1 77.8%; G3+ 0%; overall 77.8%); ICANS (G1 0%; G3+ 0%; overall 0%); hypogammaglobulinemia (8/9, 5 recd IVIg) neutropenia (G3+ 100%); anemia (G3+ 55.6%); and thrombocytopenia (G3+ 22.2%). CRS median onset was D+3 and duration 3 days. No G3+ ICANS was reported. Tocilizumab usage was in 33.3% pts (majority for persistent G1 CRS). There was no treatment related mortality with one death due to disease progression. The research was funded by: Immuneel Therapeutics Private Limited Keywords: Aggressive B-cell non-Hodgkin lymphoma, Cellular therapies, Indolent non-Hodgkin lymphoma Conflicts of interests pertinent to the abstract S. Dhar Employment or leadership position: Immuneel Therapeutics Private Limited A. Kumar MG Employment or leadership position: Immuneel Therapeutics Private Limited J. Kumar Employment or leadership position: Immuneel Therapeutics Private Limited S. Yadav Employment or leadership position: Immuneel Therapeutics Private Limited P. Arasu Employment or leadership position: Immuneel Therapeutics Private Limited S. R. Elluru Employment or leadership position: Immuneel Therapeutics Private Limited M. M. Akheel Employment or leadership position: Immuneel Therapeutics Private Limited R. Nahar Employment or leadership position: Immuneel Therapeutics Private Limited A. Kamat Employment or leadership position: Immuneel Therapeutics Private Limited Stock ownership: Immuneel Therapeutics Private Limited

Updated phase I study results of PHE885, a T-Charge manufactured BCMA-directed CAR-T cell therapy, for patients (pts) with r/r multiple myeloma (RRMM).

8004 Background: B cell maturation antigen (BCMA) targeted CAR-T cells are approved for RRMM. Long manufacturing time and high clinical demand limit access. T-Charge, an innovative platform that reduces manufacturing time to &lt;2 days and preserves T cell stemness, results in robust expansion and prolonged CAR T cell persistence. Here we report updated results from the Phase I trial of T-Charge manufactured, fully human, BCMA CAR-T PHE885 (NCT04318327). Methods: Eligible pts had RRMM after ≥2 prior lines of therapy (tx). Pts received fludarabine and cyclophosphamide (or bendamustine) for lymphodepletion (LD) prior to PHE885 infusion. Primary objective was safety. Secondary objectives were clinical response and cellular kinetics. Results: As of December 22, 2022, 46 pts received PHE885 at the following doses: 2.5e6 (n=4), 5e6 (n=13), 10e6 (n=20), 14.3e6 (n=1), and 20e6 (n=8) CAR T cells. PHE885 was manufactured for 61% of pts at a single academic institution; these pts proceeded from apheresis to LD in a median of 16 days. Median age at enrollment was 65 y (range [R] 45-81), median prior lines of tx was 4 (R 2-10). 37% of pts had extramedullary disease; 96% were triple refractory. Despite aggressive disease, only 28% of pts required bridging chemotherapy, predominantly influenced by quick production time. 96% of pts experienced any gr cytokine release syndrome (CRS); 11% had gr 3 CRS. Median time to CRS onset was 8 (R 2-16) days and median duration was 4 (R 1-19) days. Immune effector cell-associated neurotoxicity syndrome (ICANS) occurred in 22% of pts; 7% had gr 3 ICANS. Dose limiting toxicities were experienced by 13% of pts and included gr 4 neutropenia, gr 4 lipase increase, gr 3 serum amylase increase, gr 3 neurotoxicity, gr 3 transaminitis, and gr 3 ejection fraction reduction. The most common tx-related gr ≥3 AEs included anemia (54%), neutropenia (50%), and thrombocytopenia (37%). Geo-mean peak PHE885 expansion (Cmax) was 276,000 copies/µg by qPCR and 70.6% of CD3+ T cells by flow cytometry (n=41). The PHE885 transgene was detected in 13/14 (93%) pts at 6 mo and 5/7 (71%) at 12 mo post infusion. T cells with early memory phenotype were preserved in the final product and persisted in pts post infusion. In 43 efficacy-evaluable pts, the ORR was 98%. At 10e6 dose (n=19), ORR was 100% and CRR was 42% (median follow-up of 4.9 mo [R 1.4-11.8]); 60% of 10 evaluable pts were MRD negative at 10-5 by NGS. Initial efficacy data at 20e6 and longer follow-up at active doses will also be presented. Conclusions: T-Charge manufactured PHE885 produced high response rates with no unexpected safety findings in heavily pretreated RRMM pts with aggressive disease. PHE885 expanded rapidly and showed durable persistence in vivo. Since conversion to CR/sCR has occurred as late as 18 months after infusion in this study, longer follow-up is ongoing to identify a recommended dose for future development. Clinical trial information: NCT04318327 .

Outpatient practice utilization for CAR-T and T cell engager in patients with lymphoma and multiple myeloma.

1533 Background: FDA-approved chimeric antigen receptor T-cell (CAR-T) and bispecific T cell engager (TCE) therapy are most commonly managed inpatient. Here we report our experience with hospital-based outpatient (HBO) management of patients (pts) receiving FDA-approved CAR-T or TCE and a predictive model for increased risk of early hospitalization (≤3 days post CAR-T). Methods: We reviewed the outcomes of pts who received FDA-approved CAR-T (axi-cel, brexu-cel, ide-cel, cilta-cel) or TCE (teclistamab) in the HBO unit between 3/2021 and 1/2023 at Mayo Clinic, Rochester. Results: HBO is closely integrated with inpatient practice and includes the same specialty trained clinical team. It is the first point of contact 24/7 for pts and triage evaluations. CAR-T and TCE are given on HBO followed by monitoring per REMS and as clinically needed until admission criteria is met. Remote patient monitoring (RPM) tools were used as part of outpatient monitoring. Out of 169 CAR-T pts, 87 (51%) were dosed with new indication/products (follicular lymphoma, mantle cell lymphoma, myeloma). Among those, 80 (92%) pts were dosed outpatient, among whom 21 (27%) were never hospitalized. CRS and ICANS incidences were comparable to that reported in registration studies. Median time to first admission from CAR-T infusion was 1 day (range, 0-9), with 31% (n=18/59) of admissions after day 3 post infusion. The most common cause of hospitalization was fever (n=40, 59%). Median length of hospital stay was 4 days (range, 1-49). Median time to tocilizumab (n=45, 80%), steroid (n=1, 2%), escalation of oxygen support (n=7, 12%), vasopressor (n=2, 3%), ventilator (n=1, 2%), hemodialysis (n=1, 2%) and ICU transfer (n=3, 5%) was 1 day (range, 0-31) after first admission. Use of bridging therapy, elevated CRP and LDH were predictive of early admission (ROC AUC 0.62). Four pts received teclistamab on HBO and enrolled in RPM. Data from more pts will be reported at ASCO. Conclusions: Our expanded study in CAR-T and TCE confirms that HBO is feasible and that CAR-T and TCE can be safely dosed outpatient. Approximately 31% of pts were admitted after 3 days from CAR-T infusion, and 27% of our pts were never admitted. Variables associated with aggressive disease can predict early hospitalization in pts receiving FDA-approved CAR-T. Extension of HBO practice to TCE is feasible.[Table: see text]

Baseline and early post-infusion biomarkers associated with optimal response to idecabtagene vicleucel (ide-cel) in the KarMMa-3 study of triple-class–exposed (TCE) relapsed and refractory multiple myeloma (RRMM).

8031 Background: Ide-cel, a B-cell maturation antigen (BCMA) chimeric antigen receptor T cell therapy, significantly improved median progression-free survival (mPFS) and overall response rate (ORR) vs standard regimens (SRs) in patients (pts) with TCE RRMM in the KarMMa-3 study (NCT03651128; Rodríguez-Otero et al. NEJM 2023). Previous analyses in KarMMa (Munshi et al. NEJM 2021) of pts with later-line (4L+) TCE RRMM identified low baseline (BL) levels and complete clearance of soluble BCMA (sBCMA, a measure of tumor burden) and early minimal residual disease (MRD) negativity as correlates of durable response to ide-cel. The current analysis explored the association between biomarkers and efficacy or severity of inflammatory adverse events of ide-cel in KarMMa-3. Methods: sBCMA levels were measured in blood samples collected from pts in KarMMa-3 at BL and regular intervals from treatment (tx) initiation until confirmed progression. MRD status was assessed in bone marrow aspirate (clonoSeq; 10-5 sensitivity) at 6 and 12 mo post infusion and reported in all pts, regardless of response. Biomarker analyses were based on pts who received ide-cel or ≥1 dose of SR. Post hoc analyses assessed correlations between biomarkers and efficacy endpoints or cytokine release syndrome (CRS) and investigator-identified neurotoxicity (iiNT); associations of interest were identified using a ranked sum test and nominal P value &lt; 0.05. Results: Lower BL sBCMA levels were associated with higher ORR ( &lt; partial response [PR] vs ≥PR) in both tx arms (ide-cel, P= 0.0223; SR, P= 0.0395), indicating this may be agnostic of the BCMA-directed modality. Lower BL sBCMA was also associated with higher complete response (CR) rate ( &lt; CR vs ≥CR) in the ide-cel arm ( P= 0.0038). Additionally, lower BL sBCMA levels in the ide-cel arm were associated with lower grade (gr) of CRS (gr 0–1 vs 2 vs ≥3; P= 0.0022) and iiNT (gr 0–1 vs ≥2; P= 0.0113); however, overlapping ranges may limit predictive utility. Further analyses will be presented. In the ide-cel arm, landmark mPFS was longer in pts with undetectable versus detectable sBCMA at 2 mo post infusion (16.3 vs 5.2 mo; HR, 0.26) or at 6 mo (16.8 vs 9.6 mo; HR, 0.62). Furthermore, landmark mPFS was also longer in pts with MRD negativity versus pts with positive/indeterminate MRD status at 6 mo (17.2 vs 5.8 mo; HR, 0.288) or at 12 mo (13.8 vs 4.6 mo; HR, 0.121). Conclusions: BL sBCMA levels correlated with response and CRS and iiNT grade in the ide-cel arm of KarMMa-3, potentially reinforcing the importance of management of BL tumor burden for optimal response to ide-cel. Early clearance of sBCMA at 2 mo, sustained clearance of sBCMA at 6 mo, and MRD negativity at 6 or 12 mo, regardless of clinical response, may be useful biomarkers for identifying pts likely to achieve a complete and durable response to ide-cel. Clinical trial information: NCT03651128 .

Effect of bispecific B7H3 x CD19 CAR T cells on host CD19 expression and CAR T cell engraftment.

10043 Background: Our experience of B7H3 chimeric antigen receptor T cells (CAR-T) revealed modest engraftment (max 4.9 cells/uL) and no objective responses on first infusion. Previous CD19 CAR T cell trials have revealed that host B Cell CD19 can drive robust engraftment and persistence even in the absence of malignant CD19 expression. We therefore developed a bispecific B7H3xCD19 CAR T cell with the intent of using host CD19 expression to drive better engraftment of the B7H3-targeting CAR. Methods: Young patients with relapsed/refractory solid tumors (R/RST) were enrolled onto a Phase 1 trial (NCT04483778) to examine the safety of autologous T cells lentivirally transduced to express either or both scFV-IgG4hinge-CD28tm-4-1BB-zeta B7H3-specific and CD19-specific CARs. The B7H3 CAR construct contained the methotrexate resistance/selection cassette DHFRdm and the tracking/suicide construct EGFRt and the CD19 CAR construct containing the tracking/suicide construct HER2tg, allowing for differential CAR tracking. CAR T cells were cultured in low-dose methotrexate to select for B7H3 containing CAR T cells and limit exposure to monospecific CD19 CAR T cells. All patients received lymphodepleting fludarabine and cyclophosphamide prior to infusion of cryopreserved CAR-T at the prescribed dose level. The maximal tolerated dose or biologically effective dose (BED) was determined based upon observed toxicity through day 28 from initial CAR-T infusion and using a 3+3 statistical design. Results: 11 subjects (age 5-23, median 18 years) enrolled and received dose level (DL) 0B (0.5 x 106 TOTAL CAR-T/kg, n = 7) or DL1B (1 x 106 TOTAL CAR-T cells/kg, n = 4). One subject experienced dose limiting toxicities at DL1 of transaminitis, hyponatremia, worsening of a pericardial effusion and hypoxia. Most common toxicities were cytokine release syndrome (CRS) (n = 4, maximum CTCAE grade 2).No occurrence of ICANS was noted. Maximum total circulating CAR-T expansion on first infusion was 796.3 cells/uL and max B7H3 expansion was 374.2 cells/uL with 7/11 continuing with ongoing detection of CAR T cells in the peripheral blood at time of last follow up (21 days to 8 months). CAR engraftment was predominated by the B7H3 CAR single expressing CAR T cells in all subjects. All subjects developed B cell aplasia which is ongoing in 10/11 subjects at time of last check (range of 21 days to 8 months). Best overall response of Stable Disease was observed in 2 of the 11 subjects infused. Conclusions: B7H3xCD19 CAR T cells robustly engraft and expand in patients with R/RST and are safe, but despite ongoing detection of the CAR T cells, no objective responses were observed. It is likely that additional measures will be required to enhance the activity of CAR-T cells to achieve objective responses. STRIvE-02 Arm C will explore the addition of pembrolizumab post bispecific CAR infusion to evaluate the effect of PD1 blockade on anti-tumor activity. Clinical trial information: NCT04483778 .