CD19-directed Chimeric Antigen Receptor T-cell Therapy Research Articles

CD19-targeted chimeric antigen receptor T-cell therapy for CNS relapsed or refractory acute lymphocytic leukaemia: a post-hoc analysis of pooled data from five clinical trials

CNS relapse of acute lymphocytic leukaemia is difficult to treat. Durable remissions of relapsed or refractory B-cell acute lymphocytic leukaemia have been observed following treatment with CD19-directed chimeric antigen receptor (CAR) T cells; however, most trials have excluded patients with active CNS disease. We aimed to assess the safety and activity of CAR T-cell therapy in patients with a history of CNS relapsed or refractory B-cell acute lymphocytic leukaemia. In this post-hoc analysis, we included 195 patients (aged 1-29 years; 110 [56%] male and 85 [44%] female) with relapsed or refractory CD19-positive acute lymphocytic leukaemia or lymphocytic lymphoma from five clinical trials (Pedi CART19, 13BT022, ENSIGN, ELIANA, and 16CT022) done at the Children's Hospital of Philadelphia (Philadelphia, PA, USA), in which participants received CD19-directed CAR T-cell therapy between April 17, 2012, and April 16, 2019. The trials required control of CNS disease at enrolment and infusion and excluded treatment in the setting of acute neurological toxic effects (>grade 1 in severity) or parenchymal lesions deemed to increase the risk of neurotoxicity. 154 patients from Pedi CART19, ELIANA, ENSIGN, and 16CT022 received tisagenlecleucel and 41 patients from the 13BT022 trial received the humanised CD19-directed CAR, huCART19. We categorised patients into two strata on the basis of CNS status at relapse or within the 12 months preceding CAR T-cell infusion-either CNS-positive or CNS-negative disease. Patients with CNS-positive disease were further divided on the basis of morphological bone marrow involvement-either combined bone marrow and CNS involvement, or isolated CNS involvement. Endpoints were the proportion of patients with complete response at 28 days after infusion, Kaplan-Meier analysis of relapse-free survival and overall survival, and the incidence of cytokine release syndrome and neurotoxicity. Of all 195 patients, 66 (34%) were categorised as having CNS-positive disease and 129 (66%) as having CNS-negative disease, and 43 (22%) were categorised as having isolated CNS involvement. The median length of follow-up was 39 months (IQR 25-49) in the CNS-positive stratum and 36 months (18-49) in the CNS-negative stratum. The proportion of patients in the CNS-positive stratum with a complete response at 28 days after infusion was similar to that in the CNS-negative stratum (64 [97%] of 66 vs 121 [94%] of 129; p=0·74), with no significant difference in relapse-free survival (60% [95% CI 49-74] vs 60% [51-71]; p=0·50) or overall survival (83% [75-93] vs 71% [64-79]; p=0·39) at 2 years between the two groups. Overall survival at 2 years was significantly higher in patients with isolated CNS involvement compared with those with bone marrow involvement (91% [82-100] vs 71% [64-78]; p=0·046). The incidence and severity of neurotoxicity (any grade, 53 [41%] vs 38 [58%]; grade 1, 24 [19%] vs 20 [30%]; grade 2, 14 [11%] vs 10 [15%]; grade 3, 12 [9%] vs 6 [9%], and grade 4, 3 [2%] vs 2 [3%]; p=0·20) and cytokine release syndrome (any grade, 110 [85%] vs 53 [80%]; grade 1, 12 [9%] vs 2 [3%]; grade 2, 61 [47%] vs 38 [58%]; grade 3, 18 [14%] vs 7 [11%] and grade 4, 19 [15%] vs 6 [9%]; p=0·26) did not differ between the CNS-negative and the CNS-positive disease strata. Tisagenlecleucel and huCART19 are active at clearing CNS disease and maintaining durable remissions in children and young adults with CNS relapsed or refractory B-cell acute lymphocytic leukaemia or lymphocytic lymphoma, without increasing the risk of severe neurotoxicity; although care should be taken in the timing of therapy and disease control to mitigate this risk. These preliminary findings support the use of these CAR T-cell therapies for patients with CNS relapsed or refractory B-cell acute lymphocytic leukaemia. Children's Hospital of Philadelphia Frontier Program.

CD19-directed CAR T-cell therapy for treatment of primary CNS lymphoma

AbstractCD19-directed chimeric antigen receptor (CD19CAR) T-cell therapy has been successful in treating several B-cell lineage malignancies, including B-cell non-Hodgkin lymphoma (NHL). This modality has not yet been extended to NHL manifesting in the central nervous system (CNS), primarily as a result of concerns for potential toxicity. CD19CAR T cells administered IV are detectable in cerebrospinal fluid (CSF), suggesting that chimeric antigen receptor (CAR) T cells can migrate from the periphery into the CNS, where they can potentially mediate antilymphoma activity. Here, we report the outcome of a subset of patients with primary CNS lymphoma (PCNSL; n = 5) who were treated with CD19CAR T cells in our ongoing phase 1 clinical trial. All patients developed grade ≥ 1 cytokine release syndrome and neurotoxicity post-CAR T-cell infusion; toxicities were reversible and tolerable, and there were no treatment-related deaths. At initial disease response, 3 of 5 patients (60%; 90% confidence interval, 19-92%) seemed to achieve complete remission, as indicated by resolution of enhancing brain lesions; the remaining 2 patients had stable disease. Although the study cohort was small, we demonstrate that using CD19CAR T cells to treat PCNSL can be safe and feasible. This trial was registered at www.clinicaltrials.gov as #NCT02153580.

CAR T-cell Therapy in Indolent Lymphoma

Introduction CD19 directed chimeric antigen receptor (CAR) T-cell therapy has had a transformative impact on the natural history of chemotherapy refractory aggressive B-cell non-Hodgkin lymphoma (B-NHL) and B-cell acute lymphoblastic leukemia (B-ALL), inducing long-term remissions in 40–50% of patients.1–5 It does this, however, at the expense of both financial and clinical toxicity. But the cost and risk of care in the absence of CAR T-cells in these instances outweighs the risk of the therapy itself, and so it has broadly been accepted as a standard of care for these patients. Moving CD19 directed CAR T-cell therapy into the slower growing, but historically incurable, indolent B-NHLs has the potential to challenge this balance between risks and benefits. Will CAR T-cells offer definitive therapy for these otherwise incurable diseases? If not, will CAR T-cells positively affect long-term survival over alternative therapies? The answer to these questions will determine how oncologists weigh the financial and clinical costs against the therapeutic benefits.

Indirect Treatment Comparison of Liso-Cel vs. Salvage Chemotherapy in Diffuse Large B-Cell Lymphoma: TRANSCEND vs. SCHOLAR-1.

Most patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL) have exhausted their treatment options and are deemed palliative. CD19-directed chimeric antigen receptor (CAR) T-cell therapy has recently been introduced as a new option for these patients. Lisocabtagene maraleucel (liso-cel) is an investigational CAR T-cell therapy that has shown promising activity in this setting. We used an unanchored matching-adjusted indirect comparison (MAIC) methodology to compare liso-cel, using individual patient-level data from the TRANSCEND NHL 001 (TRANSCEND; NCT02631044) trial, to salvage chemotherapy, using summary-level data from the SCHOLAR-1 study, for the treatment of patients with R/R LBCL. Standardized mean differences were used to evaluate imbalances between the TRANSCEND and SCHOLAR-1 studies. MAIC was conducted to determine the relative efficacy of liso-cel vs. salvage chemotherapy with regard to overall survival, complete response rate, and objective response rate. For all efficacy outcomes assessed, comparisons of clinical factors before MAIC showed that five of seven baseline characteristics were similar between the TRANSCEND and SCHOLAR-1 studies; however, age and R/R to last therapy status differed between studies, thus requiring matching and adjusting to ensure the validity of this analysis. The base case analyses demonstrated a significantly lower risk of mortality (hazard ratio, 0.5; 95% confidence interval [CI] 0.4–0.6; p < 0.001) with significantly higher rates of complete response (odds ratio, 12.9; 95% CI 8.0–20.7) and objective response (odds ratio, 7.0; 95% CI 4.6–10.5) for patients treated with liso-cel than patients treated with salvage chemotherapy. MAIC comparisons demonstrated favorable efficacy for liso-cel compared with salvage chemotherapy in the treatment of patients with R/R LBCL.Trial Registration ClinicalTrials.gov identifier: NCT02631044.

Toxicity and effectiveness of CD19 CAR T therapy in children with high-burden central nervous system refractory B-ALL.

Although recent clinical trials have demonstrated the efficacy of CD19-directed chimeric antigen receptor (CAR) T-cell therapy for refractory or relapsed B acute lymphoblastic leukemia (r/r B-ALL), most trials exclude patients with high-burden CNS leukemia (CNSL) to avoid the risk of severe neurotoxicity. There were only sparse cases describing the effect of CAR T cells on low-burden CNSL, and the safety and effectiveness of CAR T cells in high-burden CNSL remains unknown. Here, we retrospectively analyzed the results of CD19 CAR T-cell therapy in 12 pediatric patients that had low (Blasts < 20/μL in CSF) or high-burdens (Blasts or intracranial solid mass) of CNS B-ALL, that are enrolled in three clinical trials and one pilot study at Beijing Boren Hospital RESULTS: Eleven patients (91.7%) achieved complete remission (CR) on day 30, and one patient got CR on day 90 after infusion. Most patient experienced mild cytokine-release syndrome. However, of the five patients who retained > 5/μL blasts in CSF or a solid mass before CAR T-cell expansion, four developed severe (grade 3-4) neurotoxicity featured by persistent cerebral edema and seizure, and they fully recovered after intensive managements. Sustained remission was achieved in 9 of the 12 patients, resulted in a 6-month leukemia-free survival rate of 81.8% (95% CI 59.0-100). Only one patient has CNS relapse again. Our study demonstrates that CAR T cells are effective in clearing both low- and high-burden CNSL, but a high CNSL burden before CAR T-cell expansion may cause severe neurotoxicity requiring intense intervention.

Efficacy and Safety of Loncastuximab Tesirine (ADCT-402) in Relapsed/Refractory Diffuse Large B-Cell Lymphoma

Efficacy and Safety of Loncastuximab Tesirine (ADCT-402) in Relapsed/Refractory Diffuse Large B-Cell Lymphoma

Prolonged neurotoxicity in a lymphoma patient after CD19‐directed CAR T‐cell therapy: A case report and brief review of the literature

As the field of cancer therapeutics moves increasingly toward targeted and cellular therapies, this evolution comes with new hurdles. Toxicity of these therapies can result in serious adverse events that can become life-threatening. In particular, cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) are now the most common adverse effects resulting from chimeric antigen receptor (CAR) T-cell therapy. Furthermore, CAR T cells are reported to cause hyperactivation of macrophages, which in extreme cases results in hemophagocytic lymphohistiocytosis (HLH). These toxic effects result from cytokines released as a direct effect of the therapy. Physicians are evaluating inflammatory markers to monitor longitudinally cytokine stimulation and immune activation after therapy, which can help predict and gauge the severity of the cytokine storm. Prompt recognition of toxic effects and rapid intervention are essential in the management of patients receiving CAR T-cell therapy. Despite intervention, some patients still experience severe and prolonged ICANS. Herein we present a patient with lymphoma who developed prolonged ICANS and reviewed the literature on neurotoxicity and macrophage activation resulting from CD19-directed CAR T-cell therapy.

CD19-directed CAR T-cell therapy in B-cell NHL.

CD19-directed chimeric antigen receptor (CAR) T-cell therapy is a valuable new treatment option for patients with relapsed/refractory (R/R) B-cell non-Hodgkin lymphoma. The aim of this review is to give an overview of the pivotal phase I/II trials, emerging real-world evidence and ongoing trials. For decades, attempts at improvement of the poor prognosis of patients with R/R large B-cell lymphoma with new treatment regimens have been disappointing. Since the first report of CD19-directed CAR-T-cell therapy in 2010, three constructs have been tested in large phase I/II trials and resulted in 30-40% durable responses. This has led to Food and Drug Administration and European Medicines Agency approval for axicabtagene ciloleucel and tisagenlecleucel and filing of the biologics license application for lisocabtagene maraleucel. Emerging real-world evidence seems to confirm the promising results. However, considerable toxicity, mainly cytokine release syndrome and neurotoxicity limits their general applicability and not all patients intended to be treated can be bridged during the manufacturing period due to kinetics of the disease. Randomized phase III clinical trials are being conducted to test anti-CD19 CAR-T-cell therapy in the second-line and several phase II trials are aiming to improve efficacy and decrease toxicity. CD19-directed CAR-T-cell therapy has become standard of care for aggressive R/R diffuse large B-cell non-Hodgkin lymphoma (DLBCL), but challenges still remain.

Use of CD19-directed CAR T-Cell Therapy in an Infant With Refractory Acute Lymphoblastic Leukemia

Infants with KMT2A-rearranged acute lymphoblastic leukemia (ALL) have historically poor outcomes despite maximal intensification of chemotherapy. Chimeric antigen receptor (CAR) T-cell therapy has revolutionized our approach to pediatric patients with relapsed/refractory ALL. Unfortunately, infants were excluded from early CAR T-cell trials due to concerns regarding the feasibility of T-cell collection and expansion. Here, we report the use of tisagenlecleucel in an infant with chemotherapy-refractory KMT2A-rearranged ALL. While CAR T-cell therapy was not curative for this patient, collection and expansion of T-cells proved feasible despite prior chemotherapy, he achieved minimal residual disease negative remission with excellent quality of life, and it facilitated a delay in hematopoietic stem cell transplantation.

Proton Therapy as a Bridging Treatment in CAR T-Cell Therapy for Relapsed and Refractory Large B-Cell Lymphoma: Is There a Role?

Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma. Since the relapse rate of DLBCL to frontline chemoimmunotherapy and salvage autologous hematopoietic cell transplant is high, CD19-directed chimeric antigen receptor (CAR) T-cell therapy was adopted. Given the time interval needed for CAR T cells to be manufactured (3-5 weeks) and the aggressiveness of these relapsed/refractory lymphomas, some patients do not make it to the CAR T-cell infusion phase. This calls for a bridging therapy to control, debulk, and sensitize the disease during this period. Radiation therapy can serve this purpose and has shown promising results in some studies. Proton therapy, compared to standard radiation therapy, in some locations, can reduce the radiation dose to the organs at risk, which may lead to fewer side effects for patients with lymphomas. Thus, we hypothesize that proton therapy may serve as a promising bridging strategy to CAR T-cell therapy for some patients.

Hypofibrinogenemia in Patients Receiving CD19-Directed Chimeric Antigen Receptor (CAR) T-Cell Therapy for Large B Cell Lymphoma: A Single Institution Experience

<h3>Background</h3> Hypofibrinogenemia can occur after Chimeric Antigen Receptor (CAR) T-cell therapy and is sometimes associated with cytokine release syndrome. Hypofibrinogenemia is associated with increased risk of bleeding as well as thrombosis. Limited literature exists on the incidence, complications and management of hypofibrinogenemia after CAR T-cell therapy. <h3>Methods</h3> We analyzed medical records on 148 patients who received CD19-directed CAR T-cell therapy for large B-cell lymphomas between 05/2015 and 09/2019. All patients who had at least one serum fibrinogen level measured in the first 30 days after CAR T-cell infusion were included in the analysis. All patients with serum fibrinogen < 200 mg/dL [lowest normal value] had data collected on abnormalities in other coagulation parameters including PTT, PT, INR at the time of nadir serum fibrinogen level. <h3>Results</h3> Out of 148 patients, 35 had at least one serum fibrinogen level measured in the first 30 days after CAR T-cell infusion. Nadir serum fibrinogen was < 200 mg/dl in 15/35 patients: 0-100 mg/dl in 9/15 and 100-200 mg/dl in 6/15. At the time of nadir fibrinogen level, 2/15 patients had abnormalities seen in the other 3 coagulation parameters. Of the 15 patients that had serum fibrinogen level < 200 mg/dl, four had a bleeding event and one had a thrombotic event within first 30 days after CAR T-cell infusion but none of these patients had a low fibrinogen level at the time of the bleed. Given concern for increased risk of bleeding, patients with serum fibrinogen level less than 100 mg/dl were given cryoprecipitate infusions. Details of the abnormalities in the coagulation parameters are highlighted in the table. <h3>Conclusions</h3> This study describes in detail, hypofibrinogenemia seen in patients treated with CD19-directed CAR T-cell therapy in lymphoma. None of the patients experienced a major bleeding or thrombotic event with low serum fibrinogen level. These descriptive data may be used by clinicians to inform their management of hypofibrinogenemia seen in CAR T-cell patients.

Incidence and Management of Venous Thrombo-Embolism (VTE) Associated with CD19-Directed Chimeric Antigen Receptor (CAR) T-Cell Therapy: A Single Institution Experience

<h3>Background</h3> Cancer associated venous thrombo-embolism (VTE) constitutes major cause of mortality and morbidity in patients with hematological malignancies. There is limited data on the incidence and management of VTE in patients receiving chimeric antigen receptor (CAR) T-cell therapy. <h3>Methods</h3> We performed a single center retrospective study of 148 patients receiving CD19-directed CAR T-cell therapy for aggressive B-cell lymphomas between 05/2015 and 09/2019 to evaluate the incidence and management of known and new VTE phenomenon between day 0-100 after CAR T-cell infusion. <h3>Results</h3> Prophylaxis with anticoagulation (AC) was utilized in 4% (6/148) of patients between day 0-100 after CAR T-cell infusion. 19% (28/148) had known VTE prior to CAR T-cell infusion and 50% (12/28) of these were still on AC at the time of infusion. Of those on AC for prior VTE at the time of infusion, 50% (6/12) had it held between day 0-100 after CAR T-cell infusion due to low platelet count or risk of bleeding, while the remainder continued without interruption. A new episode of VTE, between day 0-100, occurred in 11% (16/148) of patients. None of these patients had previous known VTE. Of these, 75% (12/16) started therapeutic AC, however 42% (5/12) had AC held before day 100 after CAR T-cell infusion due to low platelet count or risk of bleeding. None of the patients that continued therapeutic AC in the 2 cohorts had a bleeding event. Details of the thrombotic events and management with AC are shown in the table. <h3>Conclusions</h3> This is the first study to our knowledge that describes in detail the incidence and characteristics of VTE and use of AC in lymphoma patients receiving CAR T-cell therapy. Most patients were managed with AC without complications of recurrent VTE or bleeding.

Incidence and Management of Effusions during CD19-Directed Chimeric Antigen Receptor (CAR) T-Cell Receptor Therapy in B-Cell Lymphoma: A Single Institution Experience

<h3>Background</h3> In patients with lymphoma, third space fluid accumulations may develop or worsen during cytokine release syndrome (CRS) associated with chimeric antigen receptor (CAR) T-cell therapy. Pre-existing symptomatic pleural effusions were excluded by the ZUMA-1 trial of axicabtagene ciloleucel (axi-cel) for large B cell lymphoma (LBCL) and variants. The optimal management of effusions that develop before or after axi-cel infusion in LBCL is unknown. <h3>Methods</h3> We performed a single center retrospective study evaluating 148 patients receiving CD19 CAR T-cell therapy for LBCL between 05/2015 and 09/2019. We identified all patients who developed pleural, pericardial and peritoneal effusions before (pre-CAR-T) or during the first 30 days after CAR T-cell infusion (post-CAR-T). Clinically relevant effusions were considered symptomatic based upon physician documentation. <h3>Results</h3> Total effusions and symptomatic effusions were noted in 24% (36/148) and 18% (27/148) of patients, respectively. Among 27 patients with symptomatic effusions, 59% (16/27) were pre-CAR-T effusions, 52% (14/27) persisted after day 30, and 44% (12/27) were malignant effusions. Overall, 67% of symptomatic effusions (18/27) were managed with diuretics, 44% (12/27) with a therapeutic thoracentesis or paracentesis and 33% (9/27) were observed with only supplemental oxygen provided. Six patients required pleural or abdominal catheters with a median indwelling duration of 54 (range, 29, 202) days, although 2 of these patients passed away with these indwelling catheters. Among symptomatic effusions developing only post-CAR-T (n=11), time to onset of effusion was median of 5 (range, 2-11) days and none of these patients required interventional drainage. Table 1 differentiates between effusions based on whether they were present (n = 19) or not (n = 17) prior to CAR T cell infusion. <h3>Conclusions</h3> Nearly half of all effusions diagnosed in patients receiving CAR T cell therapy develop after infusion but most can be medically managed. Patients with pre-CAR-T effusions may require procedural drainage or indwelling catheters, as these effusions may persist beyond the acute CRS period.

Immune Effector Cell-Associated Neurotoxicity Syndrome (ICANS) after CD19-Directed Chimeric Antigen Receptor T-Cell Therapy (CAR-T) for Large B-Cell Lymphoma: Predictive Biomarkers and Clinical Outcomes

Introduction : With increased use of CAR-T for relapsed/refractory (R/R) large B-cell lymphoma (LBCL), CAR-T related complications including cytokine release syndrome (CRS) and ICANS pose a significant clinical challenge. While CAR-T mediated inflammation leading to endothelial activation and blood-brain barrier disruption may play a key role in ICANS, the exact mechanism remains unclear. Prognostic or predictive biomarkers for ICANS are not well established. Recent reports (Karschnia et al, Blood 2019) suggested an association between ICANS and inferior overall survival (OS). To better understand ICANS, we herein report a single-center analysis of LBCL patients treated with CD19-directed CAR-T, exploring the associated clinical features, predictive biomarkers, and its prognostic significance. Methods: Patients (pts) with R/R LBCL treated with axicabtagene ciloleucel (Axi-cel) between 4/2018-5/2019 were identified. Data regarding patient and disease characteristics, treatment course, and clinical outcomes was collected (Table 1). Laboratory variables were collected at time of mononuclear cell harvest, day of initiation of lymphodepletive therapy, and day of CAR-T infusion (D0). CRS and ICANS were graded per the Lee and CTCAE v4.03 criteria, respectively. Time to progression (TTP) and OS were estimated by the Kaplan-Meier method and groups compared with the logrank test. Cox Proportional Hazard Model was applied for prognostic modeling. Binary logistic regression was used for multivariable analysis of patient characteristics at D0 associated with ICANS. Results: Forty-five pts with R/R LBCL (35 DLBCL, 7 TFL, 3 PMBCL) treated with Axi-cel were identified (Table 1). Twenty-five pts developed ICANS: n=7 with Grade (Gr) I-II, n=18 with Gr III-IV. Most common initial ICANS symptoms were dysgraphia, confusion, and somnolence; median time to ICANS was 5 days (range 3-11 days). Acute abnormalities were seen on brain MRI in 7 (28%) ICANS pts; EEG done in 10 ICANS pts showed diffuse slowing in all pts and focal slowing in 3 pts. All ICANS pts had preceding CRS, treated with tocilizumab (n=25, median 2.5 doses) and siltuximab (n=2). Twenty-three (92%) pts with ICANS required steroid therapy, with a median total dose equivalent to 221 mg of dexamethasone for a median duration of 12.5 days. Two pts exhibited protracted neurotoxicity manifested by short-term memory loss and profound weakness with immobility. Twenty-two (49%, 95% CI 34-64%) pts achieved CR, 16 PR, and 5 PD. At time of analysis, n=18 had disease relapse/progression and n=35 were alive. Censoring pts that progressed, the median observation time for TTP was 9.3 months. Censoring pts who died, the median observation time for OS was 7.9 months. At 9 months OS (±1 SE) was 76.1%±7.4%, and 56.0%±8.0% were progression-free. Logistic regression showed increasing fibrinogen level at D0 was associated with increasing risk of ICANS (p=0.003) and specifically, Gr III-IV ICANS [p&lt;0.001, OR 3.02 for a case with a D0 fibrinogen of 533.5 mg/dL (3rd quartile of population distribution) vs. 382 mg/dL (1st quartile)]. Germinal center B-cell (GCB) subtype was also associated with risk of Gr III-IV ICANS (p=0.022, OR=11.9). Patient age, sex, race, disease stage at diagnosis, and D0 platelet count, WBC, LDH, CRP, and ferritin were not predictive of ICANS. ICANS was not associated with TTP (p=0.66, HR=1.24, 95% CI 0.48-3.2) nor with OS (p=0.47, HR=1.67, 95% CI 0.42-6.7). Elevated baseline fibrinogen was associated with inferior TTP (p=0.04, HR=1.89, 95% CI 1.03-3.5) and shorter OS (p=0.07, HR=2.12, 95% CI 0.94-4.8); Neither duration nor total dose of steroid treatment significantly affected TTP or OS. Conclusion: ICANS after Axi-cel for R/R LBCL was seen in approximately 50% of patients, 72% of which was severe (Gr III-IV). Contrary to prior reports, no association was seen between development of ICANS and TTP or OS. Elevated D0 fibrinogen and GCB subtype identified pts at higher risk for ICANS. D0 fibrinogen was also a prognostic marker for inferior TTP and OS. The novel finding of baseline fibrinogen as a marker both predictive of ICANS and prognostic for treatment outcomes after CAR-T may be attributed to its role in inflammation and vascular injury, which warrants further investigation. Disclosures Hutnick: Kite/Gilead: Other: Yescarta Speakers Bureau, Speakers Bureau. Badros:Celgene Corporation: Consultancy; Amgen: Consultancy.

Immunologic and Brain Bases of Neurotoxicity Associated with CAR T-Cell Therapy

Introduction: CD19-directed chimeric antigen receptor (CAR)-T cell therapy has revolutionized the treatment for B-cell acute lymphoblastic leukemia (ALL), inducing complete remission in 70-90% of highly refractory patients. Unfortunately, CAR-T cell therapy is associated with immune effector cell-associated neurotoxicity syndrome (ICANS) in 40% of patients, which presents as confusion, memory impairment, aphasia, altered level of consciousness and/or delirium. The neurobiological and immune bases of ICANS remain poorly understood, and identifying them will help develop strategies for early intervention to mitigate ICANS. Methods: From an ongoing prospective, longitudinal study, we report on the first 7 patients with relapsed ALL (age 5-19 years, 5 males) who underwent comprehensive assessments at baseline before lympho-depleting (LD) chemotherapy (fludarabine and cyclophosphamide) and infusion of CD19-directed CAR T-cells, and post-infusion, on days 10 and 28. These assessments included multimodal magnetic resonance imaging (MRI) of the brain (anatomical, perfusion, diffusion tensor imaging and MR spectroscopy), neuropsychological testing, serum measures of blood-brain barrier permeability and cytokines, and immune cell profiles in peripheral blood using mass cytometry by time-of-flight (CyTOF). We also acquired multimodal MRI and neuropsychological testing in 9 healthy controls (age 5-20 years, 7 males), once, at baseline. MRI data were acquired on a 3T Philips MR scanner using a 32 channel head coil without the use of sedatives or contrast agents and were processed blind to the diagnosis and order of data acquisition. Results: In our cohort of 7 patients, 5 developed cytokine release syndrome and 4 developed ICANS. Brain imaging findings are demonstrated in figures 1 (cortical thickness) and 2 (blood perfusion). Prior to CAR T-cell infusion patients relative to healthy controls had thinner cortex bilaterally across large portions of the brain. By post-infusion day 10, cortical thickness decreased in the postcentral gyrus (PoG) and posterior temporal lobe (pTL). Subsequently, by post-infusion day 28, cortex thickened in the PoG but continued thinning in the pTL. Patients relative to controls had lower regional cerebral blood flow (rCBF) in the thalamus, insular cortex, and cingulate gyrus, and higher rCBF in the genu of the corpus callosum (gCC). By post-infusion day 10, rCBF increased in the thalamus and decreased in the putamen and gCC. By post-infusion day 28, rCBF in the thalamus decreased and reverted towards baseline values, whereas rCBF in gCC continued to decrease away from baseline values. CyTOF analyses, as expected, showed expansion of monocytes and myeloid-derived suppressor cells by post-infusion day 10. Furthermore, in these immune cells, phosphorylation of key signaling proteins (e.g. extracellular-signal regulated kinase, ERK1/2) increased in response to external stimulation. Conclusions: Patients had widespread brain abnormalities at baseline compared to controls, likely because of prior therapies and/or underlying ALL. Post LD chemotherapy and CAR T-cell infusion, several brain abnormalities worsened by day 10 and then reverted toward baseline values by day 28. These temporal changes are generally consistent with clinically reported development of ICANS by day 10, which largely resolves by day 28. However, in certain regions brain measures progressively deviated from baseline and control values through day 28, suggesting some abnormalities associated with CAR T therapy may persist. Preliminary immune cell profiling implicates monocytes as a possible source of elevated cytokines following CAR T-cell infusion. Analysis for correlation of these findings with symptomatic ICANS and neuropsychological measures is ongoing. Patients on this study will also be followed at 6 months and 1 year to evaluate for long term neurological effects of CAR T-cell therapy. Figure 1: Cortical Thickness abnormalities in patients relative to healthy controls (1st panel); within-patient changes post-infusion (2nd, 3rd, &amp; 4th panel). Blue &amp; violet show decreases and orange &amp; red show increases in cortical thickness. Figure 2: Blood perfusion abnormalities in patients relative to healthy controls (1st panel); within patient changes post infusion (2nd, 3rd, &amp; 4th panel). Blue &amp; violet show decreases and orange &amp; red show increases in regional cerebral blood flow. Disclosures Pulsipher: Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz: Other: Education for employees; Adaptive: Membership on an entity's Board of Directors or advisory committees, Research Funding; Miltenyi: Research Funding; Bellicum: Consultancy; Amgen: Other: Lecture; CSL Behring: Membership on an entity's Board of Directors or advisory committees; Medac: Honoraria. Wayne:Spectrum Pharmaceuticals: Consultancy, Research Funding; AbbVie: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding; Servier: Consultancy.

Chronic lymphocytic leukemia cells impair mitochondrial fitness in CD8+ T cells and impede CAR T-cell efficacy

AbstractIn chronic lymphocytic leukemia (CLL), acquired T-cell dysfunction impedes development of effective immunotherapeutic strategies, through as-yet unresolved mechanisms. We have previously shown that CD8+ T cells in CLL exhibit impaired activation and reduced glucose uptake after stimulation. CD8+ T cells in CLL patients are chronically exposed to leukemic B cells, which potentially impacts metabolic homeostasis resulting in aberrant metabolic reprogramming upon stimulation. Here, we report that resting CD8+ T cells in CLL have reduced intracellular glucose transporter 1 (GLUT1) reserves, and have an altered mitochondrial metabolic profile as displayed by increased mitochondrial respiration, membrane potential, and levels of reactive oxygen species. This coincided with decreased levels of peroxisome proliferator-activated receptor γ coactivator 1-α, and in line with that, CLL-derived CD8+ T cells showed impaired mitochondrial biogenesis upon stimulation. In search of a therapeutic correlate of these findings, we analyzed mitochondrial biogenesis in CD19-directed chimeric antigen receptor (CAR) CD8+ T cells prior to infusion in CLL patients (who were enrolled in NCT01747486 and NCT01029366 [https://clinicaltrials.gov]). Interestingly, in cases with a subsequent complete response, the infused CD8+ CAR T cells had increased mitochondrial mass compared with nonresponders, which positively correlated with the expansion and persistence of CAR T cells. Our findings demonstrate that GLUT1 reserves and mitochondrial fitness of CD8+ T cells are impaired in CLL. Therefore, boosting mitochondrial biogenesis in CAR T cells might improve the efficacy of CAR T-cell therapy and other emerging cellular immunotherapies.

Chimeric Antigen Receptor T Cells for B-Cell Acute Lymphoblastic Leukemia.

Chimeric antigen receptor (CAR) T-cell therapy is transforming the landscape for treatment of B-lineage acute lymphoblastic leukemia (B-ALL). Chimeric antigen receptor T-cell therapy makes use of T cells that have been modified to target a cancer-specific cell surface antigen. There is currently 1 Food and Drug Administration-approved CD19-directed CAR T-cell therapy for relapsed/refractory B-ALL with numerous other CAR T-cell products under clinical investigation. This review covers the development of CAR T cells for B-ALL, citing the remarkable efficacy of inducing remissions in a very high-risk population of patients. However, following the first round of CAR T-cell trials targeting CD19 in B-ALL, it has been found that approximately 50% of patients who initially respond will ultimately recur. Current efforts in the field are focusing on the identification of targets beyond CD19 as well as advancing strategies to promote more durable remissions as work is ongoing to move this therapy upfront.

Factors affecting lymphocyte collection efficiency for the manufacture of chimeric antigen receptor T cells in adults with B-cell malignancies.

The clinical and procedural parameters that affect the optimal collection of lymphocytes for the production of chimeric antigen receptor (CAR) T cells remain undefined but are increasingly important, as commercial products are now available. We evaluated determinants of low lymphocyte collection efficiency (CE) and the rate of successful CAR T-cell manufacture in middle-aged and older adults with advanced B-cell malignancies. Mononuclear cell collections using two apheresis platforms (COBE Spectra and Spectra Optia, Terumo BCT) from patients participating in a CD19-directed CAR T-cell therapy trial were reviewed. Patient- and disease-specific factors, peripheral blood counts, apheresis parameters, and product cell counts were analyzed to determine effects on lymphocyte CE. Ninety-two apheresis events from patients with acute lymphocytic leukemia (ALL) (n = 28), chronic lymphocytic leukemia (n = 18), and non-Hodgkin lymphoma (n = 46) were available for analysis. Forty-one collections (45%) had a lymphocyte CE of <40%. On multivariable analysis, age (every 10-year increase, odds ratio [OR] = 1.51; p = 0.034), disease type (chronic lymphocytic leukemia vs. ALL, OR = 0.24; p = 0.052; non-Hodgkin lymphoma vs. ALL, OR = 0.20; p = 0.009) and precollection platelets (every 10 × 103 /μL increase, OR = 1.07; p = 0.005) were appreciably associated with a lymphocyte CE of <40%. No major apheresis complications occurred. Lymphocyte collection at our center was well tolerated and 100% successful in manufacturing CD19-directed CAR T cells from adult patients with B-cell malignancies despite low CE in some patients. A diagnosis of ALL, advancing age, and higher preapheresis platelet counts were observed to be associated with low CE.

Effect of Methylphenidate and Duloxetine on Neurotoxicity in CAR-T: A Case Study

Introduction Chimeric Antigen Receptor (CAR) T-cell therapy is a promising therapy for B-cell malignancies; however, it is associated with serious adverse effects including cytokine release syndrome and neurotoxicity. The incidence of neurotoxicity in two landmark trials ranged from 40-64%.1,2 Common signs and symptoms of neurotoxicity may include confusion, delirium, tremor, agitation, headache, personality changes, somnolence and dysphasia/aphasia. We report a case of severe neurotoxicity followed by significant depression and abulia. Methods We reviewed the case of a patient who experienced neurotoxicity after CD19 directed CAR T-cell therapy. The patient developed grade 2 neurotoxicity by CTCAE v4.0 consisting of aphasia, facial droop, nystagmus, tongue fasciculations, handwriting changes, and paranoid delirium. The patient was treated with intravenous dexamethasone 10mg every 6 hours with worsening of neurotoxicity during steroid taper. The patient was discharged on oral dexamethasone when medically stable then subsequently readmitted with different neurocognitive manifestations including failure to thrive, profound personality changes, passive suicidal ideation, abulia, paranoia, depression, and weakness. The patient had stopped taking all medications, including steroids, and refused all medical care. Steroids were not restarted due to steroid myopathy and psychosis. Infectious and structural complications were ruled out. Physical Medicine and Rehabilitation (PMR) was consulted. Based on evidence-based neuro-rehabilitation interventions, methylphenidate and duloxetine were recommended. Results The patient was started on methylphenidate 10mg twice daily and duloxetine extended release 30mg daily. Within 24 hours, the patient showed marked improvement with motivation to participate in medical care, improvement in anhedonia, and resolution of passive suicidal ideation. The patient showed significant improvement in physical function after participation in a multimodal inpatient rehabilitation program. Conclusion Significant improvement in neurocognitive function was seen within 24 hours after the initiation of methylphenidate and duloxetine. We propose this drug combination as a potential treatment in CAR-T patients with neurocognitive dysfunction as sequelae of neurotoxicity.

Optimized T-cell receptor-mimic chimeric antigen receptor T cells directed toward the intracellular Wilms Tumor 1 antigen

CD19-directed chimeric antigen receptor (CAR) T cells are clinically effective in a limited set of leukemia patients. However, CAR T-cell therapy thus far has been largely restricted to targeting extracellular tumor-associated antigens (TAA). Herein, we report a T-cell receptor-mimic (TCRm) CAR, termed WT1-28z, that is reactive to a peptide portion of the intracellular onco-protein Wilms Tumor 1(WT1), as it is expressed on the surface of the tumor cell in the context of HLA-A*02:01. T cells modified to express WT1-28z specifically targeted and lysed HLA-A*02:01+ WT1+ tumors and enhanced survival of mice engrafted with HLA-A*02:01+, WT1+ leukemia or ovarian tumors. This in vivo functional validation of TCRm CAR T cells provides the proof-of-concept necessary to expand the range of TAA that can be effectively targeted for immunotherapy to include attractive intracellular targets, and may hold great potential to expand on the success of CAR T-cell therapy.