Signs Of Cytokine Release Syndrome Research Articles

Human anti-PSCA CAR macrophages possess potent antitumor activity against pancreatic cancer

Due to the limitations of autologous chimeric antigen receptor (CAR)-T cells, alternative sources of cellular immunotherapy, including CAR macrophages, are emerging for solid tumors. Human induced pluripotent stem cells (iPSCs) offer an unlimited source for immune cell generation. Here, we develop human iPSC-derived CAR macrophages targeting prostate stem cell antigen (PSCA) (CAR-iMacs), which express membrane-bound interleukin (IL)-15 and truncated epidermal growth factor receptor(EGFR) for immune cell activation and a suicide switch, respectively. These allogeneic CAR-iMacs exhibit strong antitumor activity against human pancreatic solid tumors invitro and invivo, leading to reduced tumor burden and improved survival in a pancreatic cancer mouse model. CAR-iMacs appear safe and do not exhibit signs of cytokine release syndrome or other invivo toxicities. We optimized the cryopreservation of CAR-iMac progenitors that remain functional upon thawing, providing an off-the-shelf, allogeneic cell product that can be developed into CAR-iMacs. Overall, our preclinical data strongly support the potential clinical translation of this human iPSC-derived platform for solid tumors, including pancreatic cancer.

Dual-targeting CD33/CD123 NANOBODY T-cell engager with potent anti-AML activity and good safety profile

AbstractNovel therapies are needed for effective treatment of acute myeloid leukemia (AML). Relapse is common and salvage treatment with cytotoxic chemotherapy is rarely curative. CD123 and CD33, 2 clinically validated targets in AML, are jointly expressed on blasts and leukemic stem cells in >95% of patients with AML. However, their expression is heterogenous between subclones and between patients, which may affect the efficacy of single-targeting agents in certain patient populations. We present here a dual-targeting CD33/CD123 NANOBODY T-cell engager (CD33/CD123-TCE) that was designed to decrease the risk of relapse from possible single antigen-negative clones and to increase coverage within and across patients. CD33/CD123-TCE killed AML tumor cells expressing 1 or both antigens in vitro. Compared with single-targeting control compounds, CD33/CD123-TCE conferred equal or better ex vivo killing of AML blasts in most primary AML samples tested, suggesting a broader effectiveness across patients. In a disseminated cell-line–derived xenograft mouse model of AML, CD33/CD123-TCE cleared cancer cells in long bones and in soft tissues. As cytokine release syndrome is a well-documented adverse effect of TCE, the compound was tested in a cytokine release assay and shown to induce less cytokines compared to a CD123 single-targeting control. In an exploratory single-dose nonhuman primate study, CD33/CD123-TCE revealed a favorable PK profile. Depletion of CD123 and CD33 expressing cells was observed, but there were neither signs of cytokine release syndrome nor clinical signs of toxicity. Taken together, the CD33/CD123 dual-targeting NANOBODY TCE exhibits potent and safe anti-AML activity and promises a broad patient coverage.

Granulocyte transfusion during cord blood transplant for relapsed, refractory AML is associated with massive CD8+ T-cell expansion, significant cytokine release syndrome and induction of disease remission.

In high-risk myeloid malignancy, relapse is reduced using cord blood transplant (CBT) but remains the principal cause of treatment failure. We previously described T-cell expansion in CBT recipients receiving granulocyte transfusions. We now report the safety and tolerability of such transfusions, T-cell expansion data, immunophenotype, cytokine profiles and clinical response in children with post-transplant relapsed acute leukaemia who received T-replete, HLA-mismatched CBT and pooled granulocytes within a phase I/II trial (ClinicalTrials.Gov NCT05425043). All patients received the transfusion schedule without significant clinical toxicity. Nine of ten patients treated had detectable measurable residual disease (MRD) pre-transplant. Nine patients achieved haematological remission, and eight became MRD negative. There were five deaths: transplant complications (n = 2), disease (n = 3), including two late relapses. Five patients are alive and in remission with 12.7 months median follow up. Significant T-cell expansion occurred in nine patients with a greater median lymphocyte count than a historical cohort between days 7-13 (median 1.73 × 109 /L vs. 0.1 × 109 /L; p < 0.0001). Expanded T-cells were predominantly CD8+ and effector memory or TEMRA phenotype. They exhibited markers of activation and cytotoxicity with interferon-gamma production. All patients developed grade 1-3 cytokine release syndrome (CRS) with elevated serum IL-6 and interferon-gamma.

Evaluation of anakinra in the management of patients with COVID-19 infection: A randomized clinical trial.

The global COVID-19 pandemic led to substantial clinical and economic outcomes with catastrophic consequences. While the majority of cases has mild to moderate disease, minority of patients progress into severe disease secondary to the stimulation of the immune response. The hyperinflammatory state contributes towards progression into multi-organ failure which necessitates suppressive therapy with variable outcomes. This study aims to explore the safety and efficacy of anakinra in COVID-19 patients with severe disease leading to cytokine release syndromes. In this open-label, multi-center, randomized clinical trial, patients with confirmed COVID-19 infection with evidence of respiratory distress and signs of cytokine release syndrome were randomized in 1:1 ratio to receive either standard of care (SOC) or anakinra (100 mg subcutaneously every 12 h for 3 days then 100 mg subcutaneously once daily for 4 days) in addition to SOC. The primary outcome was treatment success at day 14 as defined by the WHO clinical progression score of ≤3. Primary analysis was based upon intention-to-treat population, with value of p of <0.05. Out 327 patients screened for eligibility, 80 patients were recruited for the study. The mean age was 49.9 years (SD = 11.7), with male predominance at 82.5% (n = 66). The primary outcome was not statistically different (87.5% (n = 35) in anakinra group vs. 92.5% (n = 37) in SOC group, p = 0.712; OR = 1.762 (95%CI: 0.39-7.93). The majority of reported adverse events were mild in severity and not related to the study treatment. Elevated aspartate aminotransferase was the only significant adverse event which was not associated with discontinuation of therapy. In patients with severe COVID-19 infection, the addition of anakinra to SOC treatment was safe but was not associated with significant improvement according to the WHO clinical progression scale. Further studies are warranted to explore patients' subgroups characteristics that might benefit from administered therapy. Trial registration at ClinicalTrials.gov, identifier: NCT04643678.

Plasma Microbial Cell-Free DNA to Characterize Infection Vs Cytokine Release Syndrome in Pediatric Patients with B ALL after CAR T Cell Therapy

Introduction Chimeric antigen receptor (CAR) T cell therapy is a promising treatment for pediatric patients with relapsed or refractory B cell acute lymphoblastic leukemia (R/R B ALL). Cytokine release syndrome (CRS) is a common toxicity characterized by fever and hemodynamic instability due to pro-inflammatory cytokines. Patients receiving CAR-T cell therapy are also at high risk of infection. Because both infection and CRS present with fever and signs of inflammation, they can be difficult to distinguish. Karius Inc has developed and validated a novel method for detecting and quantifying microbial cell free DNA (mcfDNA) in plasma for over 1000 species. McfDNA of organisms observed above background at statistically significant levels are reported in molecules per microliter (MPM). This retrospective cohort study sought to describe bacterial Karius Test®(KT) results, concordance with blood culture results, and association with signs of CRS in pediatric patients in the first 2 months after CAR-T cell infusion for R/R B ALL. Methods We identified 27 patients who had received CAR-T cell therapy at Lucile Packard Children's Hospital between November 2017 and March 2021 with banked plasma samples available for KT. Patients received CARs targeting CD19, CD22, or CD19-CD22 bispecific. We performed KT prior to CAR-T infusion, week 1, week 2, week 3 and week 4 or later. KT results were classified as likely pathogenic if MPM was >300 or if the same organism was detected on 2 consecutive tests. Results KT results are summarized in Table 1. Five patients had a least 1 positive blood culture in the 2 months post CAR-T infusion. Two of these patients had concurrent KT results that detected the same organism. Patient 3 experienced coagulase negativeStaphylococcus (CONS) bacteremia on days 0-2 post CAR-T. He was febrile a few hours after CAR-T infusion with no signs of CRS. KT was positive for Staphylococcus epidermidis on day -6 and day +3 after CAR-T infusion at MPM of 104,913 and 17,957, respectively. Patient 20 had grade 3 CRS by day 9 which improved after tocilizumab and steroids. She had recurrence of fevers at Day 24 and was treated with broad spectrum antimicrobials as well as immunosuppressive therapy for CRS. Blood cultures were persistently positive for CONS. She developed severe hyperammonemia at Day 56 with no evidence of hepatic dysfunction and subsequently progressed to cerebral edema and died on day 60 post CAR-T. Mycoplasma hominis was detected by bacterial sequencing on autopsy. KT detected M. hominis at a very low level (MPM 104) on day 21 post CAR-T. Subsequent measurements found increasing MPM for M. hominis at 89,071 on day 52 and then 201,096 on day 57 (Figure 1). Case reports have described M. hominis as a cause of severe hyperammonemia in immunocompromised patients. The 3 remaining patients (Patients 1, 2, and 30) did not have positive KT results for various reasons. Patient 1 experienced Enterococcus faecium bacteremia on day 23 but did not have a banked sample available for KT. This was in the setting of fevers and hypotension after progression of leukemia post CAR-T. Patient 2 had Streptococcus mitis bacteremia on day 11 post CAR-T and was started on cefepime. His KT was positive for Escherichia coli (but not s. mitis) at 11,559 MPM on day 14. He did not have blood cultures drawn that day so it is unclear if this KT result would have been detected on blood culture. Patient 30 had one blood culture positive for CONS. She was briefly treated with cefepime which was discontinued when subsequent cultures were negative. The CONS was thought to be a contaminant. KT was negative. Patients 2 and 30 had blood cultures sent in the setting of persistent fevers with rising inflammatory markers and Grade 1 CRS. Analysis across the cohort suggests KT positivity may correlate with periods of increased inflammation after CAR-T infusion. The relationship between KT positivity, inflammatory laboratory values, elevated temperature, and CRS score will be presented. Conclusions KT results may be helpful in identifying organisms in febrile patients following CAR-T when other diagnostic measures are unrevealing. This is especially true for fastidious organisms that may not grow in blood culture. Increased KT positivity during times of inflammation after CAR-T may reflect low level translocation rather than environmental contaminants. More work is needed to determine how best to use KT clinically in this patient population. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

CD22-Targeted CAR-Modified T-Cells Safely Induce Remissions in Children and Young Adults with Relapsed, CD19-Negative B-ALL after Treatment with CD19-Targeted CAR T-Cells

Introduction: Children and young adults with B-lymphoblastic leukemia (B-ALL) who relapse with CD19 antigen loss after CD19-targeted CAR T-cell therapy have a dismal prognosis, with a median overall survival of 9.7 months. Novel immunotherapies are urgently needed for this population. CD22 can serve as a potential alternative target. In our initial pilot trial of CD22-targeted/4-1BB CAR T cells, clinical activity was unexpectedly poor. Based on additional preclinical work demonstrating that shorter scFv linkers improve T-cell effector function, a novel CD22/4-1BB CAR construct with a short scFv linker (CART22-65s) was developed and investigated in a phase 1 study (NCT02650414). Methods: After fludarabine/cyclophosphamide lymphodepletion, patients (pts) were infused with CART22-65s using a 3-day fractionated dosing scheme with the 2nd/3rd doses held for early signs of cytokine release syndrome (CRS). The primary endpoint was safety. Key secondary endpoints were feasibility, efficacy, and CAR T cell expansion and persistence. Results: Nineteen pts were enrolled and had a product successfully manufactured. Of 17 pts infused (median age, 16 years; range 3-28 years), all had CD19-negative, relapsed disease after prior CD19-directed therapy (CART19, n=16; blinatumomab, n=1); 8 had prior inotuzumab; 9 had prior stem cell transplant (SCT); and 3 had multiple prior SCTs. Median bone marrow blasts immediately pre-infusion was 31% (range, 0-99%); 8 patients had >75% blasts. The median cell dose infused was 4x106 CART22-65s cells/kg (range, 0.8 to 10 x 106). In vivo cellular kinetics by qPCR demonstrated robust initial CAR T cell proliferation peaking at a median of 20 days post-infusion, and persistence that correlated with clinical response (Figure A). At day 28, 13/17 (77%) pts achieved a complete remission (CR) of which 10 (77%) had undetectable minimal residual disease (uMRD) by flow cytometry. One additional pt cleared MRD at month 2 without intervention. Notably, 4/5 (80%) pts refractory to prior inotuzumab achieved a CR with CART22-65s. Of 11 pts with a best response of uMRD CR, 5 proceeded to consolidative SCT, including 3 with prior SCT: 2 remain in CR post-SCT, 2 are in CR after a brief course of alternative therapy for emergence of MRD, and 1 had a CD22+ relapse post-SCT. Of 6 pts with uMRD CR who did not proceed to SCT (5 had a prior SCT), 5 experienced relapsed disease with a range of CD22 expression and 1 remains in CR 30 months after infusion with ongoing CAR T persistence. Of 2 pts with MRD+ CR (1 CD22+, 1 CD22-), both progressed to morphologic relapse; one received alternative therapy prior to progression. Of 4 pts with non-response, all died of disease within 9 months. Thus, with a median follow-up of 29 months, median relapse-free, event-free, and overall survival were 5.3 (95% CI, 1.9-NR), 5.8 (95% CI, 2.1-NR), and 16.5 (95% CI, 9.3-NR) months, respectively (Figure B). In addition, 2 patients received CART22-65s retreatment for CD22+ relapsed disease after initial infusion. Both engrafted, but only 1 achieved uMRD CR. CRS was observed in 15 pts (grade 1, n=10; grade 2, n=5), and mild neurotoxicity in 6 pts (grade 1, n=5; grade 2, n=1). In the retreatment setting, 1 pt developed grade 3 CRS, which resolved, and grade 3 encephalopathy/hypotonia, but died of progressive disease prior to resolution. Autopsy findings were consistent with leukomyelopathy of the spinal cord, which was inconclusive in its relation to CART22-65s. Other SAEs included: (1) platelet refractoriness and recurrent, severe inflammatory reactions to platelet transfusions in 1 pt that improved with corticosteroids and anakinra; and (2) delayed hemophagocytic lymphohistiocytosis in 1 pt after CART22-65s retreatment that resolved without intervention. Conclusion: CART22-65s induced remissions in 77% of children and young adults with highly refractory, CD19-negative B-ALL, including in 4/5 pts refractory to prior CD22-directed therapy. Manufacturing was successful, and the overall toxicity profile was favorable even in pts with high disease burden. Several uncommon toxicities were observed, but the only grade 3 CRS and neurotoxicity events occurred in the retreatment setting. Our observation of high initial response rates, but later recurrences, highlights the need to use CART22-65s as part of combination therapy. These promising preliminary data provide support for a combined CD19/22 approach using the CART22-65s construct. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

CD19 Antigen Occupancy on Cancer Cells with the CD19 Monoclonal Antibody Tafasitamab Improves the Activation, Antitumor Efficacy, and Safety Profile of CART19 Cell Therapy

Background Major limitations to CD19-targeted chimeric antigen receptor T (CART19) cell therapy include suboptimal antitumor activity and development of life-threatening toxicities such as cytokine release syndrome (CRS) and neurotoxicity. CART-associated toxicities are directly related to CART activation and proliferation in vivo. Emerging data suggest that CART over-activation contributes to therapeutic failure. Objective We hypothesized that modulation of CART activation reduces the risk of CRS while enhancing CART efficacy. Specifically, we hypothesized that using the clinically-approved CD19 monoclonal antibody tafasitamab prior to CART19 therapy can reduce tumor pyroptosis (inflammatory lytic programmed cell death), modulate CART activation, and enhance CART therapeutic index. Results First, we tested the optimal sequencing of tafasitamab and CART19 in preclinical models. We used a 4-1BB costimulated CART19 construct, similar to FDA-approved tisagenlecleucel. Our data indicate that sequential use of tafasitamab followed by CART19 ameliorated overactivation, prevented apoptosis, and improved antitumor activity of CART19 in xenograft models (Sakemura et al, ASH 2021). Given the reduction of CART19 apoptosis after treatment with tafasitamab, we aimed to determine the effect of tafasitamab on tumor pyroptosis. Here, we measured the level of high mobility group box-1 (HMGB-1) in CD19+ tumor cells after co-culture with CART19 and tafasitamab. CD19 modulation with tafasitamab resulted in a significant reduction of HMGB-1, which indicates reduced tumor pyroptosis. Given these in vitro results, we aimed to study how CD19 occupancy with tafasitamab prior to CART19 infusion impacts tumor pyroptosis in vivo. We utilized a mouse model that mimics CART toxicities. Immunocompromised NSG mice were inoculated via tail vein with 3-5x106 leukemic cells derived from patients with relapsed/refractory acute lymphoblastic leukemia (Sterner et al. Blood 2019, Sakemura et al. Cancer Immunol Res. 2021). Three weeks later, tumor burden was assessed by peripheral blood sampling. Leukemic cells were defined as murine CD45- and human CD45+CD19+CD20+ via flow cytometry, and volumetric absolute number was calculated. Mice were then randomized according to tumor burden to receive IgG control antibody one week before CART19 infusion [Group 1 (G1)], 5 mg/kg/day of tafasitamab one week before CART19 infusion (G2) or no treatment (G3). CRS was determined by weight loss, development of motor weakness, poor body posture, and elevated serum cytokine levels (e.g., IL-6, MCP-1, sCD40L, and GM-CSF). Prior to CART19 infusion, absolute number of CD19 molecules on tumor cells was quantified with antigen-binding capacity beads. G2 showed significant reduction of unbound/detectable CD19 molecules on the leukemic cell surface compared to G1 and G3. On day 0, 3x106 luciferase+CART19 were injected into G1 and G2 via tail vein. Mice were monitored with weekly bioluminescent imaging to track and quantify CART19 expansion and daily weighing and physical assessment to detect toxicity. G1 demonstrated significant weight reduction, motor weakness, and rapid CART19 expansion compared to G2. G1 reached an endpoint within 5 days of CART19 administration due to CRS, while G2 had delayed weight reduction and CART19 expansion. However, all mice from G2 remained healthy and did not display signs of CRS, including motor weakness and hunched posture. On day 5, CRS-related serum cytokines/chemokines were significantly elevated in G1 compared to G2. Overall survival was significantly longer in G2 (Fig 1A). Spleens were harvested, weighed, and assessed with flow cytometry. Spleens from G1 and G3 were significantly enlarged and were mainly composed of CD20+ leukemic cells compared to G2 spleens, which were smaller and infiltrated with CD3+ CART cells but not leukemic cells. Satellite mice were euthanized on day 1 and spleens were harvested. Western blot analysis revealed that mice from G1 showed significantly lower expression of apoptosis-inducing protein Gasdermin E (GSDME) and higher expression of cleaved GSDME on leukemic cells compared with G2, indicating reduced tumor pyroptosis in G2 (Fig 1B). Conclusions In summary, CD19 binding with tafasitamab improved leukemic disease control and decreased the incidence and severity of CRS after CART19 administration in vivo, in part through the reduction of tumor pyroptosis. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Phase I dose escalation of LAVA-051, a novel bispecific gamma-delta T-cell engager (Gammabody), in relapsed/refractory hematological malignancies.

2577 Background: LAVA-051 is a 27kD humanized bispecific single domain antibody (VHH) that directly engages CD1d and the Vδ2-TCR chain of Vγ9Vδ2-T cells and additionally stabilizes the interaction between CD1d and type 1 NKT cells (Nature Cancer 2020;1:1054-1065) to mediate potent killing of CD1d-expressing tumor cells. By engaging innate-like T cell subsets with inherent antitumor activity, namely Vγ9Vδ2-T and type 1 NKT cells, LAVA-051 has the potential to combine high therapeutic efficacy with limited off-tumor toxicity. CD1d is expressed by tumor cells in the majority of patients with CLL (chronic lymphocytic leukemia) and MM (multiple myeloma), while expression in AML (acute myeloid leukemia) is most pronounced on (myelo)monocytic subtypes. Tolerability studies in non-human primates with cross-reactive surrogate bispecific γδ-T cell engagers showed a good safety profile without signs of CRS (cytokine release syndrome). Methods: This is an open label, accelerated titration design, phase 1/2a study in patients with relapsed/ refractory CLL, MM, and AML (NCT04887259). The phase 1 study starts with single-patient cohorts for the first 3 dose levels followed by a 3+3 design. The primary objectives of the study are to investigate the safety and tolerability of LAVA-051 and to determine its recommended Phase 2a dose (RP2D). Secondary objectives of the study include evaluation of PK, PD, immunogenicity, and preliminary antitumor activity. The (flat) starting dose was determined to be 0.45 µg. LAVA-051 is administered by IV infusion over 2 hours twice a week. Results: As of Feb 14, 2022, a dose level of 45 µg has been reached with no reports of CRS (ASTCT grading) or dose limiting toxicities (DLTs). Six patients in total have been treated with LAVA-051; 4 patients (2 MM, 2 CLL) were evaluable for DLTs during cycle 1 at dose levels 0.45 µg, 3 µg, 15 µg and 45 µg. Treatment emergent AEs (TEAEs) (CTCAEv5.0) were predominantly of grade 1 and 2 severity (e.g. fever, chills, and headache). One patient (45 µg) reported a grade 2 infusion related reaction (IRR) that lasted less than 12 hours following the first administration only. Frequency and severity of TEAEs did not increase with escalating doses and all TEAEs were reversible. One patient with CLL developed symptoms consistent with a tumor flare reaction during cycle 1, and continues on cycle 5 of treatment with stable disease at 15 µg. PK data indicate increasing drug exposure in correlation with increasing doses of LAVA-051, and PD data indicate a dose-dependent increase in LAVA-051 receptor occupancy of the Vγ9Vδ2-T cell receptor. Importantly, no consistent or significant changes in measured cytokines have been observed. Updated results will be presented at the congress. Conclusions: LAVA-051 has been well tolerated early in dose escalation with on-mechanism pharmacodynamics consistent with Vγ9Vδ2-T cell engagement. Clinical trial information: NCT04887259.

CART22-65s Co-Administered with huCART19 in Adult Patients with Relapsed or Refractory ALL

CART22-65s Co-Administered with huCART19 in Adult Patients with Relapsed or Refractory ALL

Successful Outpatient Administration of Blinatumomab Infusion in Pediatric Patients with Acute Lymphoblastic Leukemia

Introduction:Acute lymphoblastic leukemia (ALL) is the most common type of pediatric cancer. Unfortunately, approximately 15% of children with high-risk B-cell ALL (B-ALL) relapse after frontline chemotherapy. Treatment of relapsed/refractory B-ALL is still challenging, and more effective novel therapies are urgently warranted. Blinatumomab, a first in class bispecific antibody therapeutic, has demonstrated superiority compared to standard chemotherapy in patients with B-ALL and has a manageable toxicity profile. Blinatumomab functions by binding to CD19 expressed on B-cells and CD3 expressed on T-cells, resulting in T-cell-mediated killing of CD19-positive cells common in B-cell malignancies.Despite remarkable efficacy and a manageable toxicity profile compared to standard-of-care chemotherapy, blinatumomab poses unique healthcare system challenges related to preparation, administration, toxicity monitoring, and medication error prevention. The drug's success in helping patients achieve complete remission relies on its continuous and uninterrupted administration. In order to ensure that it is delivered in the safest and most effective manner, education on its unique logistical and administration challenges is imperative.Objectives:The primary objective of this study is to describe and share the 6 years of institutional experience on the outpatient delivery of blinatumomab for the management of pediatric patients with B-ALL as per Children's Oncology Group protocols, as well as to retrospectively analyze the safety of this novel 28-day home-based therapy.Methods:A multidisciplinary team composed of physicians, nurses, and pharmacists was created to address administration challenges associated with blinatumomab infusions. Although blinatumomab requires a 28-day continuous infusion, it is not necessary for patients to remain hospitalized for the entire cycle. To ensure tolerability prior to discharge, patients are monitored closely during the first 3 days of Cycle 1 and 2 days of Cycle 2 for signs of cytokine release syndrome and neurological toxicities. Once discharged, they are seen every 96/72 hours for bag changes in either an outpatient hematology/oncology unit or by home health for those off study.Results:A total of 16 patients were treated with blinatumomab between May 2015 and June 2021; 10 were newly diagnosed and 6 were in first relapse. Of the 26 total infusions, 24 were successfully completed without significant adverse reactions. Two patients treated for relapsed disease had to discontinue therapy; one experienced neurotoxicity within 72 hours of blinatumomab infusion initiation and the other developed refractory disease and was switched to another protocol. No adverse events were observed in the home setting.Discussion:The team was successfully able to transform the original inpatient-only blinatumomab protocol to the outpatient setting. Retrospective analysis over 6 years demonstrates a clinically significant reduced rate of complications of blinatumomab administration in comparison to previous reports (Amicucci et al. 2021), which can be attributed to careful multidisciplinary team planning and delivery. This study confirms the feasibility of a home-based continuous blinatumomab infusion without adverse effects on safety. Additionally, this outpatient protocol leads to cost savings associated with reduced length of stay and an overall improved quality of life for pediatric patients able to receive therapy at home with their caregivers. DisclosuresNo relevant conflicts of interest to declare.

The course of action for effective anti-cytokine treatment in COVID-19

The course of action for effective anti-cytokine treatment in COVID-19

Effect of anti-interleukin drugs in patients with COVID-19 and signs of cytokine release syndrome (COV-AID): a factorial, randomised, controlled trial

BackgroundInfections with SARS-CoV-2 continue to cause significant morbidity and mortality. Interleukin (IL)-1 and IL-6 blockade have been proposed as therapeutic strategies in COVID-19, but study outcomes have been conflicting. We sought to study whether blockade of the IL-6 or IL-1 pathway shortened the time to clinical improvement in patients with COVID-19, hypoxic respiratory failure, and signs of systemic cytokine release syndrome.MethodsWe did a prospective, multicentre, open-label, randomised, controlled trial, in hospitalised patients with COVID-19, hypoxia, and signs of a cytokine release syndrome across 16 hospitals in Belgium. Eligible patients had a proven diagnosis of COVID-19 with symptoms between 6 and 16 days, a ratio of the partial pressure of oxygen to the fraction of inspired oxygen (PaO2:FiO2) of less than 350 mm Hg on room air or less than 280 mm Hg on supplemental oxygen, and signs of a cytokine release syndrome in their serum (either a single ferritin measurement of more than 2000 μg/L and immediately requiring high flow oxygen or mechanical ventilation, or a ferritin concentration of more than 1000 μg/L, which had been increasing over the previous 24 h, or lymphopenia below 800/mL with two of the following criteria: an increasing ferritin concentration of more than 700 μg/L, an increasing lactate dehydrogenase concentration of more than 300 international units per L, an increasing C-reactive protein concentration of more than 70 mg/L, or an increasing D-dimers concentration of more than 1000 ng/mL). The COV-AID trial has a 2 × 2 factorial design to evaluate IL-1 blockade versus no IL-1 blockade and IL-6 blockade versus no IL-6 blockade. Patients were randomly assigned by means of permuted block randomisation with varying block size and stratification by centre. In a first randomisation, patients were assigned to receive subcutaneous anakinra once daily (100 mg) for 28 days or until discharge, or to receive no IL-1 blockade (1:2). In a second randomisation step, patients were allocated to receive a single dose of siltuximab (11 mg/kg) intravenously, or a single dose of tocilizumab (8 mg/kg) intravenously, or to receive no IL-6 blockade (1:1:1). The primary outcome was the time to clinical improvement, defined as time from randomisation to an increase of at least two points on a 6-category ordinal scale or to discharge from hospital alive. The primary and supportive efficacy endpoints were assessed in the intention-to-treat population. Safety was assessed in the safety population. This study is registered online with ClinicalTrials.gov (NCT04330638) and EudraCT (2020-001500-41) and is complete.FindingsBetween April 4, and Dec 6, 2020, 342 patients were randomly assigned to IL-1 blockade (n=112) or no IL-1 blockade (n=230) and simultaneously randomly assigned to IL-6 blockade (n=227; 114 for tocilizumab and 113 for siltuximab) or no IL-6 blockade (n=115). Most patients were male (265 [77%] of 342), median age was 65 years (IQR 54–73), and median Systematic Organ Failure Assessment (SOFA) score at randomisation was 3 (2–4). All 342 patients were included in the primary intention-to-treat analysis. The estimated median time to clinical improvement was 12 days (95% CI 10–16) in the IL-1 blockade group versus 12 days (10–15) in the no IL-1 blockade group (hazard ratio [HR] 0·94 [95% CI 0·73–1·21]). For the IL-6 blockade group, the estimated median time to clinical improvement was 11 days (95% CI 10–16) versus 12 days (11–16) in the no IL-6 blockade group (HR 1·00 [0·78–1·29]). 55 patients died during the study, but no evidence for differences in mortality between treatment groups was found. The incidence of serious adverse events and serious infections was similar across study groups.InterpretationDrugs targeting IL-1 or IL-6 did not shorten the time to clinical improvement in this sample of patients with COVID-19, hypoxic respiratory failure, low SOFA score, and low baseline mortality risk.FundingBelgian Health Care Knowledge Center and VIB Grand Challenges program.

T Cells Genetically Modified to Express an Anti-B-Cell Maturation Antigen Chimeric Antigen Receptor with a CD28 Costimulatory Moiety Cause Remissions of Poor-Prognosis Relapsed Multiple Myeloma

▪B-cell maturation antigen (BCMA) is expressed by normal plasma cells and the malignant plasma cells of multiple myeloma (MM). We developed the first anti-BCMA chimeric antigen receptor (CAR-BCMA). CAR-BCMA includes an anti-BCMA single-chain variable fragment, a CD28 costimulatory domain, and a CD3-zeta T-cell activation domain (Carpenter et al. Clinical Cancer Research 2013. Vol. 19. 2048-2060). We used a gamma-retroviral vector to genetically modify autologous T cells to express CAR-BCMA. We are conducting a phase I clinical trial of CAR-BCMA T cells. On this trial, patients receive a chemotherapy regimen of 300 mg/m2 of cyclophosphamide and 30 mg/m2 of fludarabine on days -5 to -3 followed by an infusion of CAR-BCMA T cells on day 0. Chemotherapy is administered to increase the activity of CAR T cells by depleting endogenous leukocytes. Twenty-three patients have received CAR-BCMA T cells on one of 4 dose levels, 0.3x106, 1x106, 3x106, and 9x106 CAR+ T cells/kg of bodyweight. All patients treated on the lower dose levels and 2 patients treated on the highest dose level have been reported previously (Ali et al. Blood 2016. 128(13). 1688-1700). This abstract exclusively covers the 13 patients treated to date on the highest dose level of 9x106CAR-BCMA T cells/kg.The median age of the 13 patients was 54 years (range 43-66). The patients had a median of 11 prior lines of therapy. Five patients (12, 19, 20, 23, and 25), had a history of the poor-prognosis chromosome 17p-deletion prior to protocol enrollment. The monoclonal protein produced by each patient's MM and the number of prior therapies of each patient are shown in the table.Toxicities were consistent with prior reports of cytokine-release syndrome (CRS) after infusions of CAR T cells. The most prominent, signs of CRS were fever, tachycardia, hypotension, and reduced cardiac function. CRS grades are in the table. Of thirteen patients, 4 received the interleukin (IL)-6-receptor antagonist tocilizumab to treat CRS; 2 of these 4 patients also received corticosteroids. While CAR-BCMA T-cell toxicity was severe in some cases, the toxicities were mainly limited to the first 2 weeks after CAR-BCMA T-cell infusion. Because of Grade 3 and 4 CRS experienced by some patients with high bone marrow myeloma burdens, we modified the clinical protocol to only allow enrollment of patients with lower myeloma burdens defined as MM making up 30% or less of bone marrow cells. Two patients (16 and 18) experienced delayed neutropenia and thrombocytopenia that started approximately 1 month after CAR T-cell infusion when blood counts had recovered from the chemotherapy administered before CAR-BCMA T-cell infusions. These patients were treated with filgrastim, eltrombopag, and prednisone based on the hypothesis that the cytopenias were caused by CAR T cells in the patient's bone marrow. At the time of delayed cytopenias, 15 percent of Patient 16's bone marrow T cells were CAR+, and 16.5 percent of Patient 18's bone marrow T cells were CAR+. In both cases, cytopenias resolved after approximately 1 month.CAR-BCMA T cells exhibited clear anti-myeloma activity. Nine of 11 evaluable patients obtained objective anti-myeloma responses with 2 stringent complete responses, 5 very good partial responses, and 2 partial responses; the duration of responses varied. The longest response to date is 66 weeks (Table). Eight of 10 evaluable patients obtained minimal residual disease negative status by bone marrow flow cytometry. Consistent with BCMA-specific T-cell activity, plasma cells were reduced on bone marrow core biopsies in all 8 evaluated patients and absent in 4 of these patients 2-3 months after CAR-BCMA T-cell infusion.CAR+ cell levels have been quantified in the blood of patients. CAR T cell levels peaked in the first 2 weeks after infusion and persisted at lower levels for many months in some cases. Cytokines were measured in the serum of all patients. In patients with CRS, multiple cytokines including interferon-gamma, IL-6, IL-8, and IL-17A were consistently elevated in the serum.These results demonstrate that CAR-BCMA T cells can induce responses in poor-prognosis MM. Accrual to this trial continues. Toxicity was significant but limited in duration and controllable. A compelling atribute of CAR T-cells is that they have a mechanism of action different from other MM therapies. The results reported here should encourage research to improve CAR T-cell therapies for MM. [Display omitted] DisclosuresWang:Acerta Pharma: Consultancy, Research Funding; Asana Biosciences: Research Funding; BeiGene: Research Funding; Celgene: Honoraria, Research Funding; Dava Oncology: Honoraria; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; June Therapeutics: Research Funding; Kite Pharma: Research Funding; Onyx: Research Funding; Pharmacyclics: Research Funding; Proteolix: Honoraria, Research Funding. Kochenderfer:Bluebird bio: Research Funding; Kite Pharma: Research Funding; N/A: Patents & Royalties: I have multiple patents in the CAR field.

Immunological analysis of the murine anti‐CD3‐induced cytokine release syndrome model and therapeutic efficacy of anti‐cytokine antibodies

The aberrant release of inflammatory mediators often referred to as a cytokine storm or cytokine release syndrome (CRS), is a common and sometimes fatal complication in acute infectious diseases including Ebola, dengue, COVID‐19, and influenza. Fatal CRS occurrences have also plagued the development of highly promising cancer therapies based on T‐cell engagers and chimeric antigen receptor (CAR) T cells. CRS is intimately linked with dysregulated and excessive cytokine release, including IFN‐γ, TNF‐α, IL 1, IL‐6, and IL‐10, resulting in a systemic inflammatory response leading to multiple organ failure. Here, we show that mice intravenously administered the agonistic hamster anti‐mouse CD3ε monoclonal antibody 145‐2C11 develop clinical and laboratory manifestations seen in patients afflicted with CRS, including body weight loss, hepatosplenomegaly, thrombocytopenia, increased vascular permeability, lung inflammation, and hypercytokinemia. Blood cytokine levels and gene expression analysis from lung, liver, and spleen demonstrated a hierarchy of inflammatory cytokine production and infiltrating immune cells with differentiating organ‐dependent kinetics. IL‐2, IFN‐γ, TNF‐α, and IL‐6 up‐regulation preceded clinical signs of CRS. The co‐treatment of mice with a neutralizing anti‐cytokine antibody cocktail transiently improved early clinical and laboratory features of CRS. We discuss the predictive use of this model in the context of new anti‐cytokine strategies to treat human CRS.

Safety and Efficacy of Ex Vivo Expanded Healthy Donor-Derived Double Negative T Cells for the Treatment of AML Relapsed after Allogeneic Stem Cell Transplantation: A First in-Human Phase I/IIa Clinical Trial

BACKGROUND Relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the main cause of treatment failure for patients with acute myeloid leukemia (AML). Conventional treatments such as donor lymphocyte infusions (DLI) or secondary allo-HSCT as a monotherapy or in combination with novel agents or immunotherapy showed limited improvements on long-term survival. Our previous studies have shown that a rare subset of CD4- and CD8- double negative T cells (DNTs) expanded from periphery of healthy donors are effective in targeting AML cells in vitro and in xenograft models. Also, allogeneic DNTs can be used as an off-the-shelf adoptive cellular therapy (ACT) for AML. We undertook a first in-human phase I/IIa trial to assess the safety and efficacy of escalating doses of DNTs for the treatment of AML patients relapsed post allo-HSCT. This study protocol was approved by Chinese Ethics Committee of Registering Clinical Trials. Informed consent was obtained in accordance with the Declaration of Helsinki. The trial was registered on the Chinese Clinical Trial Registry (ChiCTR-IPR-1900022795). METHODS From June 2019 to June 2020, 12 patients with relapsed AML after allo-HSCT were enrolled in the trials. Three patients received HLA-matched sibling stem cell transplant, and 9 patients received umbilical cord blood transplantation (UCBT). Hematological relapse was found in 9 cases, and molecular relapsed in 3 cases. None of the patients were able to obtain DLI from previous donors for various reasons. Clinical-grade DNTs from peripheral blood of healthy donors were expanded. After lymphodepleting chemotherapy with fludarabine and cyclophosphamide, each patient received three infusions of HLA-mismatched DNTs expanded from healthy volunteers at escalating doses of 5×107, 1×108, or 2-4×108 per kilogram of body weight at one week interval. Numbers of total DNTs and donor-derived DNTs, inflammatory cytokines levels in vivo were measured according to the study protocol. Post-remission therapy was permitted 14 days after the last DNTs infusion according to treating physician's discretion. RESULTS All surviving patients were followed until August 1st, 2020. At a median follow-up of 4.3 months (range 1.7 to 12.2 months), 1 patient withdrew from the trial after the second DNT infusion for a personal reason. 6/11 patients (54.5%) achieved complete response (CR) with 5 of these patients negative for (45.4%) minimal/measurable residual disease (MRD). 4/11 patients (36.3%) achieved partial remission. Up to the last follow-up, 4/11 patients remain CR. Increase in the levels of serum inflammatory cytokines, including interleukin (IL)-6, TNF-alpha, MCP-1, and MIP-1-beta over baseline were observed without signs of cytokine release syndrome, neurotoxicity, or graft-versus-host disease. The most common adverse events related to DNTs treatment were fever and headache. None of the patients showed &amp;gt;grade 2 adverse event (AE). The maximum tolerated dose was not reached. Donor DNT cell expansion was detected as early as 6 hours after infusion and reached the peak at 24 hours after the 1st infusion in most patients, slightly increased after the 2nd and 3rd infusions, and lasted for 2 weeks after 3rd infusion. However, total DNTs increased and reached the peak at 2 weeks after 3rd infusion. CONCLUSIONS Our results show that allogeneic DNTs therapy is safe, well tolerated, and potentially effective in treating AML patients who relapsed after allo-HSCT. The total number of DNTs increased after infusion. Compared to other agents, DNTs more effectively induced complete responses in this patient population. Our on-going study is to elucidate the mechanism of DNTs-mediated leukemia clearance, and explore the use of DNTs as carrier for Chimeric Antigen Receptor or transgenic TCR to further enhance the efficacy targeting resistant AML cells. Disclosures Zhang: AbbVie: Current equity holder in publicly-traded company; University Health Network: Consultancy, Current equity holder in private company, Other: Principal Investigator, Patents &amp; Royalties.

Use of human splenocytes in an innovative humanised mouse model for prediction of immunotherapy‐induced cytokine release syndrome

ObjectivesHumanised mice have emerged as valuable models for pre‐clinical testing of the safety and efficacy of immunotherapies. Given the variety of models available, selection of the most appropriate humanised mouse model is critical in study design. Here, we aimed to develop a model for predicting cytokine release syndrome (CRS) while minimising graft‐versus‐host disease (GvHD).MethodsTo overcome donor‐induced variation, we directly compared the in vitro and in vivo immune phenotype of immunodeficient NSG mice reconstituted with human bone marrow (BM) CD34+ haematopoietic stem cells (HSCs), peripheral blood mononuclear cells (PBMCs) or spleen mononuclear cells (SPMCs) from the same human donors. SPMC engraftment in NSG‐dKO mice, which lack MHC class I and II, was also evaluated as a strategy to limit GvHD. Another group of mice was engrafted with umbilical cord blood (UCB) CD34+ HSCs. Induction of CRS in vivo was investigated upon administration of the anti‐CD3 monoclonal antibody OKT3.ResultsPBMC‐ and SPMC‐reconstituted NSG mice showed short‐term survival, with engrafted human T cells exhibiting mostly an effector memory phenotype. Survival in SPMC‐reconstituted NSG‐dKO mice was significantly longer. Conversely, both BM and UCB‐HSC models showed longer survival, without demonstrable GvHD and a more naïve T‐cell phenotype. PBMC‐ and SPMC‐reconstituted mice, but not BM‐HSC or UCB‐HSC mice, experienced severe clinical signs of CRS upon administration of OKT3.ConclusionPBMC‐ and SPMC‐reconstituted NSG mice better predict OKT3‐mediated CRS. The SPMC model allows generation of large experimental groups, and the use of NSG‐dKO mice mitigates the limitation of early GvHD.

Preemptive mitigation of CD19 CAR T-cell cytokine release syndrome without attenuation of antileukemic efficacy

AbstractImmunotherapy with the adoptive transfer of T cells redirected with CD19-specific chimeric antigen receptors (CARs) for B-lineage acute lymphoblastic leukemia (ALL) can salvage >80% of patients having relapsed/refractory disease. The therapeutic index of this emerging modality is attenuated by the occurrence of immunologic toxicity syndromes that occur upon CAR T-cell engraftment. Here, we report on the low incidence of severe cytokine release syndrome (CRS) in a subject treated with a CAR T-cell product composed of a defined ratio CD4:CD8 T-cell composition with a 4-1BB:zeta CAR targeting CD19 who also recieved early intervention treatment. We report that early intervention with tocilizumab and/or corticosteroids may reduce the frequency at which subjects transition from mild CRS to severe CRS. Although early intervention doubled the numbers of subjects dosed with tocilizumab and/or corticosteroids, there was no apparent detrimental effect on minimal residual disease–negative complete remission rates or subsequent persistence of functional CAR T cells compared with subjects who did not receive intervention. Moreover, early intervention therapy did not increase the proportion of subjects who experience neurotoxicity or place subjects at risk for infectious sequelae. These data support the contention that early intervention with tocilizumab and/or corticosteroids in subjects with early signs of CRS is without negative impact on the antitumor potency of CD19 CAR T cells. This intervention serves to enhance the therapeutic index in relapsed/refractory patients and provides the rationale to apply CAR T-cell therapy more broadly in ALL therapy. This trial was registered at www.clinicaltrials.gov as #NCT020284.

Third-Generation CAR T Cells Targeting CD19 Are Associated with an Excellent Safety Profile and Might Improve Persistence of CAR T Cells in Treated Patients

Introduction T cells transduced with a chimeric antigen receptor (CAR) have demonstrated significant clinical efficacy in patients with lymphoid malignancies including relapsed or refractory (r/r) B-lineage acute lymphoblastic leukemia (ALL) or r/r B-cell non-Hodgkin's lymphoma (NHL). Second-generation CAR T cells comprising 4-1BB or CD28 as costimulatory domains have become commercially available for the treatment of patients with CD19+ lymphoid malignancies. However, achievement of durable clinical responses remains a challenge in CAR T cell therapy. Consequently, third-generation CARs incorporating both elements might display short-term efficacy with potent and rapid tumor elimination (CD28) as well as long-term persistence (4-1BB). So far, only two clinical trials employing third-generation CAR T cells have been reported. Both enrolled 31 patients in summary and demonstrated favorable results for third-generation CAR T cells. Here, we report on first results of our investigator-initiated trial (IIT) on third-generation CD19-directed CAR T cells: The Heidelberg CAR trial 1 (HD-CAR-1; NCT03676504; EudraCT 2016-004808-60) is a phase I/II trial initiated in September 2018 with in-house leukapheresis and CAR T cell manufacturing in full compliance with European Good Manufacturing Practice (GMP) guidelines at the University Hospital Heidelberg. Methods Adult and pediatric patients with r/r ALL and patients with r/r chronic lymphocytic leukemia (CLL) or NHL including diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL) or mantle cell lymphoma (MCL) are treated with autologous T lymphocytes transduced with a CD19 targeting third-generation CAR retroviral vector (RV-SFG.CD19.CD28.4-1BBzeta). The main purpose of HD-CAR-1 is to evaluate safety and feasibility of escalating third-generation CAR T cell doses (1-20×106 transduced cells/m2) after lymphodepletion with fludarabine (30 mg/m2/d on days -4 to -2) cyclophosphamide (500 mg/m2/d on days -4 to -2). Patients are monitored for cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS) and/or other toxicities. In vivo function, survival and anti-tumor efficacy of CAR T cells are assessed. Results To date, 10 patients (3 adult ALL, 2 CLL, 2 MCL, 2 DLBCL, 1 transformed FL) have been enrolled and subjected to leukapheresis. Transduction efficiency of T lymphocytes ranged between 33%-66% and high numbers of transduced CAR T cells were harvested (70-123x106 CAR T cells). No production failure occurred. CAR T cell products were sterile and free from mycoplasma and endotoxins. The copy number per CAR T cell did not exceed 7. Eight patients (2 adult ALL, 2 CLL, 1 MCL, 2 DLBCL, 1 transformed FL) have received the CAR T cell product (6 patients: 106 transduced cells/m2; 2 patients 5×106 transduced cells/m2). No signs of CRS or ICANS &amp;gt; grade 2 have been observed. Only one patient required tocilizumab. No neurological side-effects occurred, even not in patients with involvement of the central nervous system (CNS). In quantitative real-time PCR, CAR T cells were detectable in the peripheral blood (PB) in 3 of 4 analyzed patients or the cerebrospinal fluid (CSF) of an ALL patient with CNS involvement. The CAR T cell frequency reached up to 200,000 copies/µg DNA, in some patients beyond end-of-study at day 90 after CAR T cell administration. Clinical responses to treatment were observed in 6/8 (75%) treated patients so far (2/8 patients have received CAR T cells recently and are not yet evaluable for response). Conclusion Leukapheresis and CAR T cell manufacturing were effective for all patients enrolled in the HD-CAR trial to date. Patients responded clinically to treatment despite low numbers of administered CAR T cells. CAR T cells displayed an excellent safety profile and were detectable for more than 3 months following administration. Furthermore, CAR T cells migrated into different compartments including the CSF in case of CNS involvement. For HD-CAR-1 leukapheresis, CAR T cell manufacturing, CAR T cell administration, patient monitoring and follow-up are performed in-house, providing autarky from transport or production sites outside the University Hospital Heidelberg. Altogether, HD-CAR-1 accounts to clinical evaluation of third-generation CAR T cells that might contribute to long-term CAR T cell persistence, hence improving efficient and durable responses in treated patients. Disclosures Schmitt: Therakos Mallinckrodt: Other: Financial Support . Sellner:Takeda: Employment. Müller-Tidow:MSD: Membership on an entity's Board of Directors or advisory committees. Dreger:AbbVie, AstraZeneca, Gilead, Janssen, Novartis, Riemser, Roche: Consultancy; AbbVie, Gilead, Novartis, Riemser, Roche: Speakers Bureau; Neovii, Riemser: Research Funding; MSD: Membership on an entity's Board of Directors or advisory committees, Other: Sponsoring of Symposia. Schmitt:Therakos Mallinckrodt: Other: Financial Support; MSD: Membership on an entity's Board of Directors or advisory committees, Other: Sponsoring of Symposia.

1184PD - Results of a phase I trial with MART-1 T cell receptor modified T cells in patients with metastatic melanoma

BackgroundAdoptive cell therapy (ACT) with T cell receptor (TCR) gene modified peripheral blood T cells creates large pools of tumor reactive T cells. Based on preclinical validation we have selected a high affinity MART-1-specific TCR for TCR gene therapy in metastatic melanoma (MM). Utilizing a novel GMP production protocol we performed a phase I trial to asses feasibility, safety and efficacy of TCR gene therapy in pts with MM. MethodsHLA-A2*0201+ pts with irresectable stage IIIc/IV melanoma, expressing MART-1 and MHC class I, with no standard treatment options were included. Autologous T cells were isolated via apheresis and transduced with a MP-71 retroviral vector encoding the 1D3HMCys MART-1 TCR and expanded ex vivo in presence of IL-7 and IL-15. Non-myeloablative chemotherapy was given prior to one i.v. infusion of MART-1 TCR transduced T cells in a dose escalating manner after evaluation of adverse events (AEs). Feasibility, safety (CTCAE 4.0) and ORR (RECIST 1.1) were assessed. ResultsTwelve heavily pretreated metastatic cutaneous (n=7) and uveal (n=5) melanoma (mUM) pts were treated with MART-1 TCR transduced T cells across 4 dose cohorts. Transduction efficiency was 42-76%. Viability of the cell product was 92.9-98.5%. Pt 1 received 4.56x109 MART-1 TCR transduced T cells but died 9 days post infusion due to multiple organ failure. Subsequent pts received 5x107 (n=3; cohort (c) 2), 25x107 (n=2; c3) and 10x107 (n=6; c4) cells. On-target AEs were dose-dependent and included dermatitis (10/11) max grade 3, uveitis (3/11) max grade 2 and ototoxicity (4/11) max grade 3, highest in cohort 3. Four pts (n=2 c3; n=2 c4) showed signs of cytokine release syndrome and 3 pts required tocilizumab. Objective PR by RECIST 1.1 was seen in 2 pts (17%), with a DOR of 4.2 (mUM, c4) and 8.4 (c3) months. Persistence of transduced T cells in peripheral blood was correlated with infused cell dose. ConclusionsTreatment with MART-1 TCR transduced peripheral blood T cells expanded in presence of IL-7 and IL-15 led to severe dose-dependent toxicity with a maximum tolerated dose of 10x107 transduced cells. Despite observed responses, toxicity limited further development and use of this MART-1 TCR cellular therapy in MM patients. NCT02654821. Clinical trial identificationNCT02654821. Legal entity responsible for the studyNetherlands Cancer Institute/Antoni van Leeuwenhoek hospital (NKI-AVL). FundingKWF Kankerbestrijding. DisclosureJ.H. Beijnen: Shareholder / Stockholder / Stock options, Full / Part-time employment: Modra Pharmaceuticals BV . J.V. van Thienen: Honoraria (institution), Advisory / Consultancy: Pfizer ; Honoraria (institution), Advisory / Consultancy: Novartis. C.U. Blank: Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): BMS; Honoraria (self), Advisory / Consultancy: MSD; Honoraria (self), Advisory / Consultancy: Roche; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Novartis; Honoraria (self), Advisory / Consultancy: Lilly; Honoraria (self), Advisory / Consultancy: Pfizer; Honoraria (self), Advisory / Consultancy: GSK; Honoraria (self), Advisory / Consultancy: GenMab; Honoraria (self), Advisory / Consultancy: Pierre Fabre ; Research grant / Funding (institution): NanoString. T.N. Schumacher: Advisory / Consultancy: Adaptive Biotechnologies; Advisory / Consultancy, Shareholder / Stockholder / Stock options: AIMM Therapeutics; Advisory / Consultancy, Shareholder / Stockholder / Stock options: Allogene Therapeutics; Advisory / Consultancy: Amgen; Advisory / Consultancy, Shareholder / Stockholder / Stock options: Merus; Advisory / Consultancy, Shareholder / Stockholder / Stock options: Neon Therapeutics; Advisory / Consultancy: Scenic Biotech; Advisory / Consultancy: Third Rock Ventures; Research grant / Funding (institution): Merck; Research grant / Funding (institution): Bristol-Myers Squibb; Research grant / Funding (institution): Merck KGaA; Shareholder / Stockholder / Stock options: Neogene Therapeutics; Shareholder / Stockholder / Stock options: Scenic Biotech. J.B.A.G. Haanen: Honoraria (institution), Advisory / Consultancy, Research grant / Funding (institution): BMS; Honoraria (institution), Advisory / Consultancy, Research grant / Funding (institution): MSD; Honoraria (institution), Advisory / Consultancy: Pfizer; Honoraria (institution), Advisory / Consultancy: AZ/MedImmune; Honoraria (institution), Advisory / Consultancy: Roche/Genentech; Honoraria (institution), Advisory / Consultancy: Ipsen; Honoraria (institution), Advisory / Consultancy: Bayer; Honoraria (institution), Advisory / Consultancy: Immunocore; Honoraria (institution), Advisory / Consultancy, Research grant / Funding (institution): Novartis; Honoraria (institution), Advisory / Consultancy: Seattle Genetics; Honoraria (institution), Advisory / Consultancy, Research grant / Funding (institution): Neon Therapeutics; Honoraria (institution), Advisory / Consultancy: Celsius Therapeutics; Honoraria (institution), Advisory / Consultancy: Gadet ; Honoraria (institution), Advisory / Consultancy: GSK. All other authors have declared no conflicts of interest.

PF440 CAR T‐CELL THERAPY: KNOWLEDGE GAPS AND EDUCATIONAL NEEDS FOR HEMATOLOGISTS/ONCOLOGISTS

Background:There are currently two approved chimeric antigen receptor (CAR) T‐cell therapies used for the treatment of hematologic malignancies [diffuse large B‐cell lymphoma (DLBCL) and acute lymphoblastic leukemia (ALL)].Aims:The objective of this study was to assess current clinical practices of hematologist/oncologist (hem/onc) specialists related to CAR T‐cell therapy in hematologic malignancies, in order to identify knowledge gaps and barriers to optimal care.Methods:A continuing medical education (CME)‐certified clinical practice assessment consisting of 25 multiple choice questions was developed to measure knowledge, skills, attitudes, and competence of hem/oncs regarding CAR T‐cell therapy. The survey instrument posted online 12/22/17 and was made available without monetary compensation or charge. Respondent confidentiality was maintained, and responses were de‐identified and aggregated prior to analyses. Results were grouped into learning topics to assess the association between the percentage of correct answers, patient load, practice setting, and self‐reported confidence. This analysis was conducted using RStudio (R version 3.5.1). Statistical methods used in this analysis included multiple linear regression using Ordinary Least Squares (OLS) estimates and Pearson's chi squared test (statistical significance P &lt; .05 level).Results:As of February 2019 the activity had 399 hem/onc learners and 219 were included in the outcomes assessment. Hem/onc demonstrated knowledge gaps in the following three areas. Foundational Knowledge: Over half, 61% and 62% did not know the components of a CAR construct or the FDA‐approved indication for axicabtagene ciloleucel, respectively. Knowledge of Clinical Trial Data: Over half, 68%, 75%, 68%, and 75% did not know the response rates seen in the ELIANA, ZUMA‐1, JULIET, or TRANSCEND trials, respectively. Knowledge and Competence Managing Adverse Events (AEs): Just under half, 44% and 35% did not know signs of cytokine release syndrome (CRS) or neurotoxicity associated with CAR T‐cell therapy, respectively. Over half (54%) did not know the role of corticosteroids in managing CRS and neurotoxicity. Advanced Analysis: The variables of patient load and practice setting were statistically significant predictors of the percentage of correct answers, where having a patient load &lt;6 and practicing in the community setting were each associated with lower levels of foundational knowledge and knowledge of AE management. There was not a statistically significant interaction between patient load and practice setting for either learning topic. Controlling for answering all questions, knowledge was statistically significantly associated with confidence in foundational knowledge (P &lt; .001) and managing AEs. For those who answered less than 50% of the questions correctly, 86% and 89% rated their confidence in foundational knowledge and AEs as 3 or lower (scale 1–5), respectively.Summary/Conclusion:This activity found hem/oncs lack knowledge related to CAR T‐cell therapy in the areas of foundational concepts, clinical trial data, and managing AEs. Hem/onc who practice in the community setting and hem/onc who see fewer than 6 patients with NHL or B‐cell ALL per month had lower levels of knowledge in this assessment, indicating an even higher educational need than academic providers with a higher patient load. Additional education is needed to narrow these knowledge gaps and to improve confidence of academic and community hem/oncs specialists who care for patients receiving CAR T‐cell therapy.image