CD19-specific Chimeric Antigen Receptor Research Articles

Efficacy and safety of CD19-specific CAR T cell–based therapy in B-cell acute lymphoblastic leukemia patients with CNSL

AbstractFew studies have described chimeric antigen receptor (CAR) T-cell therapy for patients with B-cell acute lymphoblastic leukemia (B-ALL) with central nervous system leukemia (CNSL) because of concerns regarding poor response and treatment-related neurotoxicity. Our study included 48 patients with relapsed/refractory B-ALL with CNSL to evaluate the efficacy and safety of CD19-specific CAR T cell–based therapy. The infusion resulted in an overall response rate of 87.5% (95% confidence interval [CI], 75.3-94.1) in bone marrow (BM) disease and remission rate of 85.4% (95% CI, 72.8-92.8) in CNSL. With a median follow-up of 11.5 months (range, 1.3-33.3), the median event-free survival was 8.7 months (95% CI, 3.7-18.8), and the median overall survival was 16.0 months (95% CI, 13.5-20.1). The cumulative incidences of relapse in BM and CNS diseases were 31.1% and 11.3%, respectively, at 12 months (P = .040). The treatment was generally well tolerated, with 9 patients (18.8%) experiencing grade ≥3 cytokine release syndrome. Grade 3 to 4 neurotoxic events, which developed in 11 patients (22.9%), were associated with a higher preinfusion disease burden in CNS and were effectively controlled under intensive management. Our results suggest that CD19-specific CAR T cell–based therapy can induce similar high response rates in both BM and CNS diseases. The duration of remission in CNSL was longer than that in BM disease. CD19 CAR T-cell therapy may provide a potential treatment option for previously excluded patients with CNSL, with manageable neurotoxicity. The clinical trials were registered at www.clinicaltrials.gov as #NCT02782351 and www.chictr.org.cn as #ChiCTR-OPN-16008526.

Characterizing piggyBat—a transposase for genetic modification of T cells

Chimeric antigen receptor (CAR) T cells targeting CD19 have demonstrated remarkable efficacy in the treatment of B cell malignancies. Current CAR T cell manufacturing protocols are complex and costly due to their reliance on viral vectors. Non-viral systems of genetic modification, such as with transposase and transposon systems, offer a potential streamlined alternative for CAR T cell manufacture and are currently being evaluated in clinical trials. In this study, we utilized the previously described transposase from the little brown bat, designated piggyBat, for production of CD19-specific CAR T cells. PiggyBat demonstrates efficient CAR transgene delivery, with a relatively low variability in integration copy number across a range of manufacturing conditions as well as a similar integration site profile to super-piggyBac transposon and viral vectors. PiggyBat-generated CAR T cells demonstrate CD19-specific cytotoxic efficacy in vitro and in vivo. These data demonstrate that alternative, naturally occurring DNA transposons can be efficiently re-tooled to be exploited in real-world applications.

Infectious Complications in Pediatric, Adolescent and Young Adult Patients Undergoing CD19-CAR T Cell Therapy.

CD19-specific chimeric antigen receptor (CAR) T cell therapy has changed the treatment paradigm for pediatric, adolescent and young adult (AYA) patients with relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL). However, data on the associated infectious disease challenges in this patient population are scarce. Knowledge of infections presenting during treatment, and associated risk factors, is critical for pediatric cellular therapy and infectious disease specialists as we seek to formulate effective anti-infective prophylaxis, infection monitoring schemas, and empiric therapy regimens. In this work we describe our institutional experience in a cohort of 38 pediatric and AYA patients with CD19-positive malignancy treated with lymphodepleting chemotherapy (fludarabine/cyclophosphamide) followed by a single infusion of CD19-CAR T cells (total infusions, n=39), including tisagenlecleucel (n=19; CD19/4-1BB) or on an institutional clinical trial (n=20; CD19/4-1BB; NCT03573700). We demonstrate that infections were common in the 90 days post CAR T cells, with 19 (50%) patients experiencing a total of 35 infections. Most of these (73.7%) occurred early post infusion (day 0 to 28; infection density of 2.36 per 100 patient days-at-risk) compared to late post infusion (day 29 to 90; infection density 0.98 per 100 patient days-at-risk), respectively. Bacterial infections were more frequent early after CAR T cell therapy, with a predominance of bacterial blood stream infections. Viral infections occurred throughout the post infusion period and included primarily systemic reactivations and gastrointestinal pathogens. Fungal infections were rare. Pre-infusion disease burden, intensity of bridging chemotherapy, lymphopenia post lymphodepleting chemotherapy/CAR T cell infusion and development of CAR-associated hemophagocytic lymphohistiocytosis (carHLH) were all significantly associated with either infection density or time to first infection post CAR T cell infusion. A subset of patients (n=6) had subsequent CAR T cell reinfusion and did not appear to have increased risk of infectious complications. Our experience highlights the risk of infections after CD19-CAR T cell therapy, and the need for continued investigation of infectious outcomes as we seek to improve surveillance, prophylaxis and treatment algorithms.

A CD123-specific chimeric antigen receptor augments anti-acute myeloid leukemia activity of Vγ9Vδ2 T cells.

Aim: To investigate whether anti-CD123 chimeric antigen receptor (CAR)-expressing Vγ9Vδ2 T cells could be an alternative for acute myeloid leukemia (AML) treatment. Materials & methods:Ex vivo expanded Vγ9Vδ2 T cells were electroporated with anti-CD123 CAR-encoding mRNA. The effector function and specificity of the modified Vγ9Vδ2 T cells were examined by in vitro cytotoxicity, degranulation and cytokine release level. The in vivo function was analyzed using the xenograft KG1-luc model with NOD-SCID-γc-/- mice. Results: The modified Vγ9Vδ2 T cells exhibited significantly improved effector activities against both AML cell lines and primary AML cells in vitro. In the xenograft mouse model, the modified Vγ9Vδ2 cells displayed an enhanced tumor control potency. Conclusion: Anti-CD123 CAR-expressing Vγ9Vδ2 T cells may serve as an alternative way to target AML.

Engineering of an Avidity-Optimized CD19-Specific Parallel Chimeric Antigen Receptor That Delivers Dual CD28 and 4-1BB Co-Stimulation.

Co-stimulation is critical to the function of chimeric antigen receptor (CAR) T-cells. Previously, we demonstrated that dual co-stimulation can be effectively harnessed by a parallel (p)CAR architecture in which a CD28-containing second generation CAR is co-expressed with a 4-1BB containing chimeric co-stimulatory receptor (CCR). When compared to linear CARs, pCAR-engineered T-cells elicit superior anti-tumor activity in a range of pre-clinical models. Since CD19 is the best validated clinical target for cellular immunotherapy, we evaluated a panel of CD19-specific CAR and pCAR T-cells in this study. First, we generated a panel of single chain antibody fragments (scFvs) by alanine scanning mutagenesis of the CD19-specific FMC63 scFv (VH domain) and these were incorporated into second generation CD28+CD3ζ CARs. The resulting panel of CAR T-cells demonstrated a broad range of CD19 binding ability and avidity for CD19-expressing tumor cells. Each scFv-modified CAR was then converted into a pCAR by co-expression of an FMC63 scFv-targeted CCR with a 4-1BB endodomain. When compared to second generation CARs that contained an unmodified or mutated FMC63 scFv, each pCAR demonstrated a significant enhancement of tumor re-stimulation potential and IL-2 release, reduced exhaustion marker expression and enhanced therapeutic efficacy in mice with established Nalm-6 leukemic xenografts. These data reinforce the evidence that the pCAR platform delivers enhanced anti-tumor activity through effective provision of dual co-stimulation. Greatest anti-tumor activity was noted for intermediate avidity CAR T-cells and derived pCARs, raising the possibility that effector to target cell avidity is an important determinant of efficacy.

Beyond CD19 CAR-T cells in lymphoma.

Adoptive transfer of CD19-specific chimeric antigen receptor T-cells (CAR-T cells) has transformed the treatment paradigm of relapsed/refractory (R/R) CD19 B-cell malignancies, dramatically improving remission rates and cures in patients with chemo-refractory disease. However, the applicability of CD19 CAR-T cells is limited to B cell malignancies and antigen loss can result in treatment failure, prompting the exploration of alternative targets to overcome tumor escape via CD19 antigen loss, as well as extend the CAR-T cell platform to treat Hodgkin and T cell lymphomas. This review highlights recent clinical trials testing CAR-T cell targets beyond CD19.

Large-scale manufacturing and characterization of CMV-CD19CAR T cells

BackgroundAdoptive transfer of CD19-specific chimeric antigen receptor (CD19CAR) T cells can induce dramatic disease regression in patients with B cell malignancies. CD19CAR T cell therapy may be limited by insufficient...

IKZF3 deficiency potentiates chimeric antigen receptor T cells targeting solid tumors.

Chimeric antigen receptor (CAR) T cell therapy has been successful in treating hematological malignancy, but solid tumors remain refractory. Here, we demonstrated that knocking out transcription factor IKZF3 in HER2-specific CAR T cells targeting breast cancer cells did not affect CAR expression or CAR T cell differentiation, but markedly enhanced killing of the cancer cells in vitro and in a xenograft model, which was associated with increased T cell activation and proliferation. Furthermore, IKZF3 KO had similar effects on the CD133-specific CAR T cells targeting glioblastoma cells. AlphaLISA and RNA-seq analyses indicate that IKZF3 KO increased the expression of genes involved in cytokine signaling, chemotaxis and cytotoxicity. Our results suggest a general strategy for enhancing CAR T efficacy on solid tumors.

Target isoforms are an overlooked challenge and opportunity in chimeric antigen receptor cell therapy.

The development of novel chimeric antigen receptor (CAR) cell therapies is rapidly growing, with 299 new agents being reported and 109 new clinical trials initiated so far this year. One critical lesson from approved CD19-specific CAR therapies is that target isoform switching has been shown to cause tumour relapse, but little is known about the isoforms of CAR targets in solid cancers. Here we assess the protein isoform landscape and identify both the challenges and opportunities protein isoform switching present as CAR therapy is applied to solid cancers.

Minicircles for CAR T Cell Production by Sleeping Beauty Transposition: A Technological Overview.

Development and application of chimeric antigen receptor (CAR) T cell therapy has led to a breakthrough in the treatment of hematologic malignancies. In 2017, the FDA approved the first commercialized CD19-specific CAR T cell products for treatment of patients with B-cell malignancies. This success increased the desire to broaden the availability of CAR T cells to a larger patient cohort with hematological but also solid tumors. A critical factor of CAR T cell production is the stable and efficient delivery of the CAR transgene into T cells. This gene transfer is conventionally achieved by viral vectors. However, viral gene transfer is not conducive to affordable, scalable, and timely manufacturing of CAR T cell products. Thus, there is a necessity for developing alternative nonviral engineering platforms, which are more cost-effective, less complex to handle and which provide the scalability requirement for a globally available therapy.One alternative method for engineering of T cells is the nonviral gene transfer by Sleeping Beauty (SB) transposition. Electroporation with two nucleic acids is sufficient to achieve stable CAR transfer into T cells. One of these vectors has to encode the gene of interest, which is the CAR , the second one a recombinase called SB transposase, the enzyme that catalyzes integration of the transgene into the host cell genome. As nucleic acids are easy to produce and handle SB gene transfer has the potential to provide scalability, cost-effectiveness, and feasibility for widespread use of CAR T cell therapies.Nevertheless, the electroporation of two large-size plasmid vectors into T cells leads to high T cell toxicity and low gene transfer rates and has hindered the prevalent clinical application of the SB system. To circumvent these limitations, conventional plasmid vectors can be replaced by minimal-size vectors called minicircles (MC ). MCs are DNA vectors that lack the plasmid backbone, which is relevant for propagation in bacteria, but has no function in a human cell. Thus, their size is drastically reduced compared to conventional plasmids. It has been demonstrated that MC-mediated SB CAR transposition into T cells enhances their viability and gene transfer rate enabling the production of therapeutic doses of CAR T cells. These improvements make CAR SB transposition from MC vectors a promising alternative for engineering of clinical grade CAR T cells.

A human orthogonal IL-2 and IL-2Rβ system enhances CAR T cell expansion and antitumor activity in a murine model of leukemia.

Interleukin-2 (IL-2) is a central T cell cytokine that promotes T cell proliferation and effector function; however, toxicity due to its pluripotency limits its application to enhance CAR T cell immunotherapy. Previously, mouse IL-2 and its cognate receptor were engineered to create an orthogonal (ortho) cytokine-cytokine receptor pair capable of delivering an IL-2 signal without toxicity. Here, we engineered a human orthogonal IL-2 (ortho-hIL-2) and human orthogonal IL-2Rβ (ortho-hIL-2Rβ) pair, containing human-specific mutations. Ortho-hIL-2 is selective toward ortho-hIL-2Rβ–expressing cells with no appreciable signaling on wild-type T cells. Ortho-hIL-2 induces IL-2 receptor signaling and supports proliferation of both an IL-2–dependent cell line and primary T cells transduced to express the ortho-hIL-2Rβ. Using CD19-specific chimeric antigen receptor (CAR) T cells, we show that ortho-hIL-2 induces a dose-dependent increase in ortho-hIL-2Rβ+ CAR T cell expansion in vivo by as much as 1000-fold at 2 weeks after adoptive transfer into immunodeficient mice bearing CD19+ Nalm6 leukemia xenografts. Ortho-hIL-2 can rescue the antileukemic effect of an otherwise suboptimal CAR T cell dose. In addition, ortho-hIL-2 administration initiated at the time of leukemic relapse after CAR T cell therapy can rescue an otherwise failed antileukemic response. These data highlight the potential of combining an orthogonal cytokine approach with T cell–based immunotherapies to augment the antitumor efficacy of engineered T cells.

Disease Burden Affects Outcomes in Pediatric and Young Adult B-Cell Lymphoblastic Leukemia After Commercial Tisagenlecleucel: A Pediatric Real-World Chimeric Antigen Receptor Consortium Report.

Tisagenlecleucel is a CD19-specific chimeric antigen receptor T-cell therapy, US Food and Drug Administration-approved for children, adolescents, and young adults (CAYA) with relapsed and/or refractory (RR) B-cell acute lymphoblastic leukemia (B-ALL). The US Food and Drug Administration registration for tisagenlecleucel was based on a complete response (CR) rate of 81%, 12-month overall survival (OS) of 76%, and event-free survival (EFS) of 50%. We report clinical outcomes and analyze covariates of outcomes after commercial tisagenlecleucel. We conducted a retrospective, multi-institutional study of CAYA with RR B-ALL across 15 US institutions, who underwent leukapheresis shipment to Novartis for commercial tisagenlecleucel. A total of 200 patients were included in an intent-to-treat response analysis, and 185 infused patients were analyzed for survival and toxicity. Intent-to-treat analysis demonstrates a 79% morphologic CR rate (95% CI, 72 to 84). The infused cohort had an 85% CR (95% CI, 79 to 89) and 12-month OS of 72% and EFS of 50%, with 335 days of median follow-up. Notably, 48% of patients had low-disease burden (< 5% bone marrow lymphoblasts, no CNS3, or other extramedullary disease), or undetectable disease, pretisagenlecleucel. Univariate and multivariate analyses associate high-disease burden (HB, ≥ 5% bone marrow lymphoblasts, CNS3, or non-CNS extramedullary) with inferior outcomes, with a 12-month OS of 58% and EFS of 31% compared with low-disease burden (OS; 85%, EFS; 70%) and undetectable disease (OS; 95%, EFS; 72%; P < .0001 for OS and EFS). Grade ≥ 3 cytokine release syndrome and neurotoxicity rates were 21% and 7% overall and 35% and 9% in patients with HB, respectively. Commercial tisagenlecleucel in CAYA RR B-ALL demonstrates efficacy and tolerability. This first analysis of commercial tisagenlecleucel stratified by disease burden identifies HB preinfusion to associate with inferior OS and EFS and increased toxicity.

Impact of High Disease Burden on Survival in Pediatric Patients with B-ALL Treated with Tisagenlecleucel

CD19-specific chimeric antigen receptor (CAR) T-cell therapies, including the FDA-approved tisagenlecleucel, induce high rates of remission in pediatric patients with relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL). However, post-treatment relapse remains an issue. Optimal management of B-ALL after tisagenlecleucel treatment remains elusive, and continued tracking of outcomes is necessary to establish a standard of care for this population. We sought to evaluate outcomes on the real-world use of tisagenlecleucel in a contemporary pediatric patient population and to identify risk factors influencing event-free survival (EFS) and overall survival (OS). Additionally, we aimed to describe post-tisagenlecleucel management strategies, including use of allogeneic hematopoietic cell transplantation (AlloHCT) or repeat CAR T-cell infusions. We report on 31 pediatric and adolescent and young adult patients (AYA) with B-ALL, treated with lymphodepleting chemotherapy followed by tisagenlecleucel. Patients were treated at Johns Hopkins Hospital and St. Jude Children's Research Hospital between March 2018 and November 2020. Data on patient, disease, and treatment characteristics were collected retrospectively from medical records and described. EFS and OS were estimated by the Kaplan-Meier method and compared by the log-rank test. Single-factor and multiple-factor analysis of EFS and OS were performed by fitting Cox regression models. Of the 30 evaluable patients, 25 (83.3%) experienced a complete response, with 21 having negative minimal residual disease. Treatment was well tolerated, with expected rates of cytokine release syndrome (61.3%) and immune effector cell-associated neurotoxicity (29%). After initial complete response, 12 patients (48%) had subsequent disease recurrence, with CD19-negative relapse (n=6) occurring sooner than CD19-positive relapse (P = .0125). With a median follow-up time of 386 days (range 11-1187 days), the EFS for the entire cohort (n = 31) at 6 and 12 months after infusion was 47% (95% confidence interval [CI], 28.4%-63.4%) and 35.2% (95% CI, 18.4%-52.5%), respectively. In multivariate analysis, high pretreatment leukemic burden (≥5% bone marrow blasts) was an independent risk factor for inferior EFS (HR 5.98 [95% CI, 1.1-32.4], P=.0380) and OS (HR 4.2 [95% CI, 1.33-13.39], P=.0148). Tisagenlecleucel induced high initial response rates in a contemporary cohort of pediatric and AYA patients with B-ALL. However, 48% of patients experienced subsequent disease relapse, including 6 with antigen-escape variants. This highlights a considerable limitation of single-agent autologous CD19-CAR T-cell therapy. Pretreatment leukemic disease burden of ≥5% blasts was significantly associated with worse outcomes in this study, including lower EFS and OS. Our findings suggest that reducing preinfusion leukemic burden is a viable treatment strategy to improve outcomes of CAR T-cell therapy.

Impact of Bridging Chemotherapy on Clinical Outcomes of CD19-Specific CAR T Cell Therapy in Children/Young Adults with Relapsed/Refractory B Cell Acute Lymphoblastic Leukemia

Chimeric antigen receptor (CAR) T cells achieve response and durable remission in patients with relapsed/refractory (R/R) B cell malignancies. Following collection of patient T cells, chemotherapy ("bridging chemotherapy") is utilized during the manufacture of CAR T cells. However, the optimal bridging chemotherapy has yet to be defined. Our objective in this study was to report clinical outcomes following bridging chemotherapy in a cohort of pediatric/young adult patients with R/R B cell acute lymphoblastic leukemia (B-ALL) treated with CAR T cell therapy. This retrospective study included patients enrolled on clinical trial NCT01860937 or referred to Memorial Sloan Kettering Cancer Center for commercial CAR T cell therapy (tisagenlecleucel). Bridging chemotherapy (given after T cell collection and before CAR T cell infusion) was defined as high intensity if myelosuppression was expected for >7 days. Outcome comparison analyses were performed in high-intensity versus low-intensity bridging chemotherapy, 1 cycle versus ≥2 cycles of bridging chemotherapy, disease burden at the start of bridging chemotherapy, disease burden at the start of bridging chemotherapy with chemotherapy intensity, tumor debulking by bridging chemotherapy, and disease burden pre-lymphodepleting chemotherapy (LDC) for CAR T cell treatment. The outcomes of this analysis showed that the incidence of grade ≥3 infection was significantly higher (94% versus 56%; P=.019) and overall survival (OS) was significantly lower (hazard ratio, 3.73; 95% confidence interval, 1.39 to 9.97; P=.006) in patients who received ≥2 cycles versus 1 cycle of bridging chemotherapy. No difference in incidence was found for cytokine release syndrome (P > .99) or neurotoxicity/immune effector cell-associated neurotoxicity syndrome (P=.70). Disease burden at the start of bridging chemotherapy, disease burden prior to LDC, and tumor debulking by bridging chemotherapy also did not significantly affect outcomes after CAR T cell therapy in this cohort. In this study, patients receiving ≥2 cycles of bridging chemotherapy had higher rates of infection and lower OS but no difference in CAR-specific toxicity. Clinicians should carefully consider the use of additional cycles of chemotherapy during the bridging period as it delays treatment with CAR T cells and increases the risk of infectious complications. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

“My T Cell”: A Smartphone Application for Guidance of CAR T Logistics and Management of CAR T & BiTE Related Toxicities

The Bispecific T-cell engager (BiTE) Blinatumomab and CD19-specific Chimeric Antigen Receptor (CAR) T-cell products are approved for the treatment of relapsed and refractory B-cell neoplasms. However, these T-cell based immunotherapies can be accompanied by immune-related toxicities differing from adverse events of classical cytotoxic agents. Toxicity management can pose a challenge for health care professionals. Additionally, logistics of CAR T-cell patient management, particularly with regard to timelines of apheresis, bridging therapies, and CAR T-cell transfusion, require coordinated efforts between referring physicians and treatment centers. To support the optimal management of these patients, we developed an interactive smartphone application (“myTcell”) which educates physicians in the pre-treatment logistics of CARs and BiTEs and provides recommendations on management and treatment of immune-related toxicities.We initiated a multi-step content development process with an extensive literature research of toxicity guidelines consented by the ASTCT, SITC, NCCN and EBMT as well as of officially released drug information. Findings were integrated in an information platform to provide diagnostic and therapeutic recommendations as well as algorithms for interactive toxicity grading tools. We could successfully implement an app (“myTcell”) guiding health workers in a disease- and product-specific step by step process through the clinical workflow of CAR and BiTE therapy (Fig.1). This includes recommendations for eligibility, patient screening, safety assessment and stopping rules prior to leukapheresis and CAR T-cell transfusion. Upon entering relevant clinical data for grading of CRS, ICANS and HLH, interactive tools display toxicity grade and grade-specific management (Fig. 2). Further, “myTcell” assists with the diagnosis and treatment of pancytopenia and infections. The app includes an overview of important publications with direct links to respective abstracts to support evidence-based decision-making. A prototype was validated at five Geman treatment centers through a questionnaire which measured the advantage of the app compared to common clinical practice.38 physicians with a median working experience of 8 years validated the app protoype in a real-world setting of CAR T-cells or BiTE application for the treatment of Diffuse Large-B-Cell Lymphoma (89.5%) and B-Cell Precursor Acute Lymphoblastic Leukemia (39.5%) at five German treatment centers (University Hospitals of LMU Munich, Cologne, Göttingen, Erlangen, Tübingen). 78.9% of the users most valued the content of toxicity management. In addition, 63.2% reported to dominantly use the interactive tools and calculators to assess severity of toxicities and to instantly receive grade-specific management recommendations. As expected, the tools were most frequently used for the two most commonly occurring side effects CRS (68.4%) and ICANS (65.8%). In addition, most of the users agreed, that the interactive tools improved toxicity management (94.7%) and saved time during their clinical practice (81.6%). Based on these results, “myTcell” has been certified as a medicinal product class I and has been released in the app stores and for desktop application (www.mytcell.de) on July 15, 2021.“myTcell” is a smartphone app supporting the use of T-cell based immunotherapy platforms. The app supports assessment and treatment of novel CAR T and BITE mediated immunotoxicities. Health care professionals validated feasibility and in particular appreciated fast and easy assessment of toxicity grading and management. Thus, “myTcell” is a tool that has the potential to improve guideline adherence and accelerate broader and safer application of CARs and BiTEs based immunotherapy. [Display omitted] DisclosuresBlumenberg: Novartis: Consultancy, Research Funding; BMS/Celgene: Research Funding; Janssen: Research Funding; Kite/Gilead: Consultancy, Research Funding. Schmidt: Bayer Healthcare: Research Funding; Novartis: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; Kite/Gilead: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Research Funding; Janssen: Other: Travel, Accommodations, Expenses; Takeda: Consultancy, Other: Travel, Accommodations, Expenses; BMS: Consultancy, Other: Travel, Accommodations, Expenses. von Bergwelt: Astellas: Honoraria, Research Funding, Speakers Bureau; Mologen: Honoraria, Research Funding, Speakers Bureau; Miltenyi: Honoraria, Research Funding, Speakers Bureau; MSD Sharpe & Dohme: Honoraria, Research Funding, Speakers Bureau; Kite/Gilead: Honoraria, Research Funding, Speakers Bureau; BMS: Honoraria, Research Funding, Speakers Bureau; Novartis: Honoraria, Research Funding, Speakers Bureau; Roche: Honoraria, Research Funding, Speakers Bureau. Buecklein: BMS/Celgene: Consultancy, Research Funding; Miltenyi: Research Funding; Kite/Gilead: Consultancy, Honoraria, Other: Congress and travel support, Research Funding; Amgen: Consultancy, Honoraria; Novartis: Consultancy, Other: congress and travel support, Research Funding, Speakers Bureau; Pfizer: Consultancy, Honoraria, Speakers Bureau. Subklewe: Janssen: Consultancy; Gilead: Consultancy, Research Funding, Speakers Bureau; Roche: Research Funding; Takeda: Speakers Bureau; Klinikum der Universität München: Current Employment; BMS/Celgene: Consultancy, Research Funding, Speakers Bureau; Amgen: Consultancy, Research Funding, Speakers Bureau; Miltenyi: Research Funding; Seattle Genetics: Consultancy, Research Funding; Pfizer: Consultancy, Speakers Bureau; Novartis: Consultancy, Research Funding, Speakers Bureau; MorphoSys: Research Funding.

Allogeneic NKT Cells Expressing a CD19-Specific CAR in Patients with Relapsed or Refractory B-Cell Malignancies: An Interim Analysis

Autologous T cells engineered to express a CD19-specific chimeric antigen receptor (CAR) mediate high rates of complete response (CR) in patients with B-cell malignancies. However, autologous cell therapy products are time- and resource-intensive to manufacture and vary in potency and toxicity. Unlike polymorphic HLA-restricted T cells, monomorphic CD1d-restricted Vα24-invariant natural killer T cells (NKTs) are not alloreactive, and therefore therapeutic NKTs can be generated from allogeneic donors without the risk of graft-versus-host disease (GvHD). Moreover, pre-clinical models suggest that CAR-NKTs have inherent advantages over CAR-T products including an ability to trans-activate NK cells, cross-prime tumor-specific CD8 T cells, and recognize CD1d-positive B-cell lymphoma cells via their endogenous NKT T cell receptor.We report interim results from five patients treated on a phase 1 dose-escalation trial of allogeneic NKTs engineered to co-express a CD19-specific CAR, IL-15, and shRNA targeting beta-2 microglobulin and CD74 for downregulation of HLA class I and class II molecules, respectively (ANCHOR, NCT00840853). Four patients with relapsed/refractory B-cell non-Hodgkin's lymphoma (NHL, cohort A) were enrolled on dose level (DL) 1 (NHL-1, -2, -3) and DL 2 (NHL-4), and 1 patient with relapsed acute B-lymphoblastic leukemia (ALL, cohort B) was enrolled on DL 1 (ALL-1). Primary and secondary objectives of the trial are to assess safety and anti-tumor responses; immune response evaluation is an additional objective. NKTs were isolated from the leukapheresis product of 1 HLA-unmatched healthy individual, transduced with the CAR, expanded ex vivo for 14 days to a total of 2.7×10 9 CAR-positive cells (99.8% NKT purity, 0.04% T cells), and cryopreserved. Patients received 10 7 (DL 1) or 3×10 7 (DL 2) CAR-NKT cells per square meter of body surface area following lymphodepleting conditioning with cyclophosphamide/fludarabine. Adverse events were evaluated per NCI criteria. When accessible, patients underwent core biopsies of an involved site at 2-5 weeks post-infusion. Response to therapy was assessed at 4 weeks per Lugano Criteria (for NHL) or NCCN guidelines (for ALL).The most common adverse effects observed were nausea and grade 3-4 hematologic toxicities related to the lymphodepletion chemotherapy. There were no early adverse events attributable to the cellular product except grade 1 cytokine release syndrome in 1 patient. Of the 4 NHL patients (all with diffuse large B cell lymphoma), 3 had a partial response (NHL-1, -2, and -4, Figure 1A) that evolved into a CR in 1 case (NHL-2). The ALL patient achieved a CR with incomplete hematologic recovery and showed no evidence of leukemia by morphology, flow cytometry, or next-generation sequencing at 4 weeks. We detected in vivo expansion of donor-derived NKT and CAR-NKT cells in the peripheral blood of NHL-4 and ALL-1 that peaked at 1 week post-infusion in both cases as determined by flow cytometry and qPCR. While CAR-NKTs were not detected in the peripheral blood of the first 3 NHL patients beyond 3 hours post-infusion, they were found in tumor tissues collected from the 2 biopsied NHL patients (Figure 1B). In patient NHL-2, we also observed a 2000-fold expansion of recipient NKTs with a skewed TCRβ repertoire; this population peaked at 6 weeks post-treatment and remained elevated through 12 weeks (Figure 1C). An ELISpot assay performed with peripheral blood from NHL-1 and NHL-2 before treatment and at 4 and 6 weeks post-therapy to detect changes in the frequency of T cells reactive to a set of tumor-associated antigens (TAAs) found no evidence for epitope spreading toward the tested TAAs.In conclusion, our data indicate that allogeneic CAR-NKT cells are well-tolerated and can mediate objective responses in relapsed/refractory NHL and ALL patients even at the low doses tested. Our initial results from this first-in-human clinical evaluation of allogeneic CAR-NKTs suggest that NKTs represent a promising platform for “off-the-shelf” cancer immunotherapy. [Display omitted] DisclosuresRamos: Tessa Therapeutics: Patents & Royalties, Research Funding; Athenex: Research Funding; Genentech: Consultancy; Novartis: Consultancy. Courtney: Athenex: Patents & Royalties, Research Funding. Metelitsa: Athenex: Patents & Royalties, Research Funding. OffLabel Disclosure:Cyclophosphamide and fludarabine are being used as lymphodepleting agents before immune effector infusion.

Suppressed Fibrinolytic Activity Demonstrated By Simultaneous Thrombin and Plasmin Generation Assay during Cytokine Release Syndrome after CD19 Chimeric Antigen Receptor-Modified T-Cell Therapy

Introduction: Infusion T cells engineering to express CD19-specific chimeric antigen receptor T cells (CAR-T) following lymphodepleting chemotherapy has shown promising efficacy in patients with relapsed and/or refractory CD19-positive B-cell malignancies including B-cell acute lymphoblastic leukemia (B-ALL), and diffuse large B-cell lymphoma (DLBCL). CAR-T therapy can often be associated with cytokine release syndrome (CRS), which has been reported to present severe coagulopathy. Conventional coagulation and fibrinolysis parameters have been reported to worsen in correlation with CRS grading [Hay KA et al. Blood 2017]. In the present study, we hypothesized that the change of balance between coagulation and fibrinolysis due to coagulopathy is associated with CRS after CAR-T therapy. To clarify our hypothesis, we investigated the global coagulation and fibrinolytic function of patients receiving CD19 CAR-T therapy using simultaneous thrombin and plasmin generation assay (T/P-GA). Patients: We enrolled 13 consecutive patients aged 23-69 years (8 males and 5 females, DLBCL; n = 11, B-ALL; n = 2) receiving CD19 CAR-T therapy from May 2020 to December 2020 at a single center in Japan. Due to a history of internal jugular venous thrombosis, one patient received edoxaban, an anticoagulant. Methods: We evaluated the global functions of coagulation and fibrinolysis using T/P-GA [Matsumoto et al. TH 2013]. This clotting was initiated by the mixture of recombinant human tissue factor (Innovin ®, f.c. 1 pM), phospholipid vesicles (f.c. 4 μM), and tissue-type plasminogen activator (f.c. 3.2 nM). We simultaneously monitored thrombin and plasmin generation using thrombin- and plasmin-specific fluorogenic substrate (Z-Gly-Gly-Arg-AMC and BOC-Glu-Lys-Lys-MAC, respectively) in separate microtiter wells. The first derivatives (velocity) of thrombin and plasmin generation were utilized to derive the parameters, lag time (LT), endogenous potential (EP), peak levels (Peak), and time to peak (ttPeak). In this study, EP of thrombin generation (T-EP) and plasmin-peak (P-Peak) were selected as parameters for evaluation. We calculated the ratio of T-EP and P-Peak of patients' plasmas to those of control normal plasma. A ratio > 1.0 was defined as high coagulation or fibrinolytic potential relative to normal. Using fibrinogen (Fbg), D-dimer, and antithrombin (AT), we also monitored the conventional laboratory markers of hemostasis. Soluble IL-2 receptor (sIL-2R) was also measured as a marker of inflammatory cytokines. Day 0 was defined as the day of CAR-T infusion. Plasmas were collected at T0; pre-lymphodepleting chemotherapy, T1; Days -2-0, T2; Days 1-3, T3; Days 4-6, T4; Days 7-9, T5; Days 10-12, T6; Days 13-18, and T7; Days 19-23. Results: All patients had Grade ≤ 2 CRS. Two cases developed CRS-associated coagulopathy, one of whom required fresh frozen plasma transfusion and cryoprecipitate for low Fbg level, and the other required tranexamic acid for hemorrhagic cystitis. The median values of AT remained within the reference value (RV). The median Fbg values were 229-525 mg/dL, and which were significantly greater at T0-T3 than at T5-T7 (p < 0.05). The median D-dimer values were 0.45-3.9 µg/mL, which were within or above the RV with no significant change between time points. The median values of sIL-2R were 819-3,953 U/mL, and which were significantly increased at T3-T4 than at T0-T1 (p < 0.05). T-EP/P-Peak revealed a median of 1,877/21.9, 1,659/18.6, 1,731/19.8, 1,856/15.0, 1,931/16.3, 1,758/18.5, 1,600/19.1, 1,634/20.3, and 1,594/17.4 nM for T0-T7 and control plasma, respectively, indicating the reduced P-Peak ratios (Fig. 1). T-EP ratios showed consistently maintaining > 1 with no significant difference between time points, while P-Peak ratios were significantly lower at T3 and T4 than at T0 (p < 0.01) (median ratios of T-EP/P-peak; T0; 1.23/1.22, T1; 1.08/1.05, T2; 1.12/1.09, T3; 1.23/0.81, T4; 1.27/0.91, T5; 1.19/1.11, T6; 1.07/1.12, and T7; 1.20/1.15, respectively). Conclusion: The results of T/P-GA showed that hemostatic kinetics in patients with Grade ≤ 2 CRS were likely to shift to hypercoagulable states throughout the entire period and that they were likely to experience hypofibrinolytic activity during the CRS phase. These results suggest that the imbalance of coagulation and fibrinolysis might cause organ disorder due to thrombotic tendency associated with CRS after CAR-T therapy. [Display omitted] DisclosuresTakaori-Kondo: Bristol-Myers K.K.: Honoraria; ONO PHARMACEUTICAL CO., LTD.: Research Funding; Celgene: Research Funding. Nogami: Chugai Pharmaceutical Co., Ltd.: Consultancy, Research Funding.

4-1BB and optimized CD28 co-stimulation enhances function of human mono-specific and bi-specific third-generation CAR T cells

BackgroundCo-stimulatory signals regulate the expansion, persistence, and function of chimeric antigen receptor (CAR) T cells. Most studies have focused on the co-stimulatory domains CD28 or 4-1BB. CAR T cell persistence...

18F]FDG PET-CT in patients with DLBCL treated with CAR-T cell therapy: a practical approach of reporting pre- and post-treatment studies.

The introduction of CD19-specific chimeric antigen receptor T-cell therapy (CAR-T) for treatment of relapsed/refractory diffuse large B cell lymphoma (R/R DLBCL) gives hope to patients with otherwise dismal prognosis. Therapy outcomes, however, depend upon selection of patients and accurate early identification of non-responders. Patients treated with CAR-T usually undergo [18F]FDG PET-CT at time of decision (TD), time of CAR-T transfusion (TT), 1month (M1), and 3months (M3) post-therapy. The purpose of the current study was to identify the specific parameters that should be addressed when reporting PET-CT studies in the clinical setting of CAR-T therapy. A total of 138 PET-CT scans (30 TD, 42 TT, 44 M1, 22 M3) of 48 patients treated with CAR-T were included. SUVmax, TMTV, and TLG were calculated in all scans. Response was assessed using the Deauville scale and ΔSUVmax method. Overall survival (OS) was the primary endpoint. Median follow-up was 12.8 (IQR 6.4-16.0) months from CAR-T infusion. In a univariate analysis, TD-SUVmax > 17.1 and TT-SUVmax > 12.1 were associated with shorter OS (Pv < 0.05). In a multivariate analysis, three factors were significantly associated with shorter OS: TD-SUVmax > 17.1 (HR 10.3; Pv < 0.01), LDH > 450 U/l (HR 7.7; Pv < 0.01), and ECOG score > 1 (HR 5.5; Pv = 0.04). Data from TD and TT PET-CT scans were not predictive of toxicity. On M1-PET-CT, patients with a Deauville score > 3 had significantly shorter OS (median 7.9months, versus not reached, Pv < 0.01). ΔSUVmax ≤ 66% on M1-PET-CT predicted shorter OS when M1-SUVmax was compared to TD-SUVmax (Pv = 0.02) but not to TT-SUVmax (Pv = 0.38). Pre-treatment SUVmax may guide patient selection for CAR-T therapy. On M1-PET-CT, Deauville score and ΔSUVmax from TD may identify early therapy failure. These parameters are easy to obtain and should be included in the PET-CT report.

Enzymatically produced piggyBac transposon vectors for efficient non-viral manufacturing of CD19-specific CAR T cells

The piggyBac transposon system provides a non-viral alternative for cost-efficient and simple chimeric antigen receptor (CAR) T cell production. The generation of clinical-grade CAR T cells requires strict adherence to current good manufacturing practice (cGMP) standards. Unfortunately, the high costs of commonly used lentiviral or retroviral vectors limit the manufacturing of clinical-grade CAR T cells in many non-commercial academic institutions. Here, we present a manufacturing platform for highly efficient generation of CD19-specific CAR T cells (CAR19 T cells) based on co-electroporation of linear DNA transposon and mRNA encoding the piggyBac transposase. The transposon is prepared enzymatically in vitro by PCR and contains the CAR transgene flanked by piggyBac 3′ and 5′ arms. The mRNA is similarly prepared via in vitro transcription. CAR19 T cells are expanded in the combination of cytokines interleukin (IL)-4, IL-7, and IL-21 to prevent terminal differentiation of CAR T cells. The accurate control of vector copy number (VCN) is achieved by decreasing the concentration of the transposon DNA, and the procedure yields up to 1 × 108 CAR19 T cells per one electroporation of 1 × 107 peripheral blood mononuclear cells (PBMCs) after 21 days of in vitro culture. Produced cells contain >60% CAR+ cells with VCN < 3. In summary, the described manufacturing platform enables a straightforward cGMP certification, since the transposon and transposase are produced abiotically in vitro via enzymatic synthesis. It is suitable for the cost-effective production of highly experimental, early-phase CAR T cell products.