Chimeric Antigen Receptor T-cell Dose Research Articles

Systemically administered low-affinity HER2 CAR T cells mediate antitumor efficacy without toxicity

BackgroundThe paucity of tumor-specific targets for chimeric antigen receptor (CAR) T-cell therapy of solid tumors necessitates careful preclinical evaluation of the therapeutic window for candidate antigens. Human epidermal growth factor...

Higher doses of tisagenlecleucel are associated with improved outcomes: a report from the pediatric real-world CAR consortium.

Remarkable complete response rates have been shown with tisagenlecleucel, a chimeric antigen receptor (CAR) T-cell therapy targeting CD19, in patients up to age 26 years with refractory/relapsed B-cell acute lymphoblastic leukemia; it is US Food and Drug Administration approved forthis indication. Currently, patients receive a single dose of tisagenlecleucel across a wide doserange of 0.2 to 5.0× 106 and 0.1 to 2.5× 108 CAR T cells per kg for patients ≤50 and >50 kg, respectively. The effect of cell dose on survival and remission is not yet well established. Our primary goal was to determine if CAR T-cell dose affects overall survival (OS), event-free survival (EFS), or relapse-free-survival (RFS) in tisagenlecleucel recipients. Retrospective data were collected from Pediatric Real World CAR Consortium member institutions and included 185 patients infused with commercial tisagenlecleucel. The median dose of viable transduced CAR T cells was 1.7× 106 CAR T cells per kg. To assess the impact of cell dose, we divided responders into dose quartiles: 0.134 to 1.300× 106 (n= 48 [27%]), 1.301 to 1.700× 106 (n= 46 [26%]), 1.701 to 2.400×106 (n= 43 [24%]), and 2.401 to 5.100× 106 (n= 43 [24%]). OS, EFS, and RFS were improved in patients who received higher doses of tisagenlecleucel (P= .031, .0079, and .0045, respectively). Higher doses of tisagenlecleucel were not associated with increased toxicity. Because the current tisagenlecleucel package insert dose range remains broad, this work has implications in regard totargeting higher cell doses, within the approved dose range, to optimize patients' potential for long-standing remission.

Taking a step forward in CAR T-cell therapy for acute myeloid leukaemia and myelodysplastic syndrome

Chimeric antigen receptor (CAR) T-cell therapies have transformed the treatment landscape of lymphoid malignancies. Six CAR T-cell products have been approved by the US Food and Drug Administration since 2017.1–5 A single dose of autologous CD19-directed CAR T-cells showed objective response rates of 64–95% for patients with relapsed or refractory B-cell malignancies, with a subset of responding patients having durable remission.1–3 Similarly, B-cell maturation antigen (BCMA) targeting CAR T-cells have yielded promising efficacy in relapsed and refractory multiple myeloma.

GPRC5D-Targeted CAR T Cells for Myeloma

BackgroundB-cell maturation antigen (BCMA)–directed chimeric antigen receptor (CAR) T-cell therapies have generated responses in patients with advanced myeloma, but relapses are common. G protein–coupled receptor, class C, group 5, member D (GPRC5D) has been identified as an immunotherapeutic target in multiple myeloma. Preclinical studies have shown the efficacy of GPRC5D-targeted CAR T cells, including activity in a BCMA antigen escape model.MethodsIn this phase 1 dose-escalation study, we administered a GPRC5D-targeted CAR T-cell therapy (MCARH109) at four dose levels to patients with heavily pretreated multiple myeloma, including patients with relapse after BCMA CAR T-cell therapy.ResultsA total of 17 patients were enrolled and received MCARH109 therapy. The maximum tolerated dose was identified at 150×106 CAR T cells. At the 450×106 CAR T-cell dose, 1 patient had grade 4 cytokine release syndrome and immune effector cell–associated neurotoxicity syndrome (ICANS), and 2 patients had a grade 3 cerebellar disorder of unclear cause. No cerebellar disorder, ICANS of any grade, or cytokine release syndrome of grade 3 or higher occurred in the 12 patients who received doses of 25×106 to 150×106 cells. A response was reported in 71% of the patients in the entire cohort and in 58% of those who received doses of 25×106 to 150×106 cells. The patients who had a response included those who had received previous BCMA therapies; responses were observed in 7 of 10 such patients in the entire cohort and in 3 of 6 such patients who received 25×106 to 150×106 cells.ConclusionsThe results of this study of a GPRC5D-targeted CAR T-cell therapy (MCARH109) confirm that GPRC5D is an active immunotherapeutic target in multiple myeloma. (Funded by Juno Therapeutics/Bristol Myers Squibb; ClinicalTrials.gov number, NCT04555551.)

Mapping CAR T-Cell Design Space Using Agent-Based Models.

Chimeric antigen receptor (CAR) T-cell therapy shows promise for treating liquid cancers and increasingly for solid tumors as well. While potential design strategies exist to address translational challenges, including the lack of unique tumor antigens and the presence of an immunosuppressive tumor microenvironment, testing all possible design choices in vitro and in vivo is prohibitively expensive, time consuming, and laborious. To address this gap, we extended the modeling framework ARCADE (Agent-based Representation of Cells And Dynamic Environments) to include CAR T-cell agents (CAR T-cell ARCADE, or CARCADE). We conducted in silico experiments to investigate how clinically relevant design choices and inherent tumor features—CAR T-cell dose, CD4+:CD8+ CAR T-cell ratio, CAR-antigen affinity, cancer and healthy cell antigen expression—individually and collectively impact treatment outcomes. Our analysis revealed that tuning CAR affinity modulates IL-2 production by balancing CAR T-cell proliferation and effector function. It also identified a novel multi-feature tuned treatment strategy for balancing selectivity and efficacy and provided insights into how spatial effects can impact relative treatment performance in different contexts. CARCADE facilitates deeper biological understanding of treatment design and could ultimately enable identification of promising treatment strategies to accelerate solid tumor CAR T-cell design-build-test cycles.

Abstract 2732: A mathematical model for optimization of combination therapy involving targeted radionuclide and CAR-T cell therapy

Abstract Background: Immunotherapy with chimeric antigen receptor - T (CAR-T) cells and targeted radionuclide therapy (TRT) are two highly promising therapies in cancer treatment. Often, these therapies show limited efficacy in complete eradication of cancer cells making the combination of these two therapies an attractive cancer treatment option. The complications involved in dosing and scheduling of these therapies make mathematical modeling an appropriate method for analyzing and predicting disease response to these therapies. Here we propose a mathematical model evaluating disease response to the combination of these two therapies and explore the optimization of their dosing and scheduling. Methods: An ordinary differential equation-based formalism is proposed for simulation of tumor response to CAR-T cell therapy as well as TRT. CAR-T cell dose and injected radioactivity was input to the model. Among others, key model parameters included tumor proliferation rate, tumor cell and CAR-T cell radiosensitivity, CAR-T cell killing rate, CAR-T cell decay rate indicating persistence. Preclinical experiments involving CS1- CAR-T cell therapy and 225Ac-DOTA-Daratumumab TRT in a multiple myeloma mice model were used to parameterize the model. Sensitivity study of the model parameters using overall survival (OS) and progression-free survival (PFS) as evaluation metrics, was performed to elucidate the parameters with highest impact. Results: OS and PFS were 97 and 55 days when CAR-T cell therapy was given prior to TRT as compared to OS of 43 days for untreated control mice. Sensitivity study of model parameters showed that tumor proliferation has the highest impact on survival metrics. For a ±50% change in tumor proliferation rate, OS changed by -41%/+111% and PFS changed by -62%/+147%. Similar changes in TRT injected activity and CAR-T cell dose changed OS by ± 15% and ±21% respectively. Accordingly, PFS changed by roughly ±32% and ±45% respectively. A variation of the interval between the therapies showed that faster growing tumors required a shorter interval between the two therapies. The sequence of therapies was also changed and TRT prior to CAR-T cell therapy demonstrated shorter PFS (43 days) due to the adverse effects of radiation on CAR-T cells. Conclusion: For a fixed dose of TRT and CAR-T cells, tumor proliferation rate was found to be the prime factor impacting therapy interval. The presented work shows the key parameters required for planning and optimizing preclinical experiments and clinical trials. Using disease, CAR-T cell and radionuclide-specific parameters as shown in this work as well as incorporating immune stimulating effects of radiation would make it an extremely potent tool for optimizing combination therapies. Citation Format: Vikram Adhikarla, Dennis Awuah, Alexander B. Brummer, Enrico Caserta, Amrita Krishnan, Flavia Pichiorri, Megan M. Minnix, John E. Shively, Jeffrey Y.C. Wong, Xiuli Wang, Russell C. Rockne. A mathematical model for optimization of combination therapy involving targeted radionuclide and CAR-T cell therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2732.

IMMU-14. SynNotch chimeric antigen receptor (CAR) T-cells as a potential treatment for diffuse intrinsic pontine glioma (DIPG)/diffuse midline glioma (DMG)

BACKGROUND: The development of effective chimeric antigen receptor (CAR) T-cell therapies for malignant pediatric brain tumors remains a challenge due to multiple barriers, including antigenic heterogeneity, on-target off-tumor toxicities, and T cell exhaustion. We have adopted a novel synthetic Notch “synNotch” receptor system and developed innovative T-cell circuits that recognize tumor cells based on the “prime-and-kill” strategy. METHODS: We created a novel synNotch-CAR circuit in which the brain/glioma-specific antigen Brevican (BCAN) primes the T cells to induce expression of a CAR that recognizes interleukin-13 receptor α2 (IL-13Rα2) and ephrin type A receptor (EphA2), thereby eradicating glioma cells expressing either antigen. Immunocompromised mice bearing the SF8628 DIPG cell line in the frontal lobe or brain stem received a single intravenous (IV) infusion of synNotch CAR T-cells (2.5 x 106 each of CD4+ and CD8+ T cells) on day 6 following the tumor inoculation. Mice were monitored for toxicity and tumor growth. RESULTS: Following this synNotch CAR T-cell dose, although tumors in the brainstem did not regress, 3 of the 5 mice with frontal lobe tumors demonstrated complete and sustained remission. Our histological analyses revealed primed CAR T-cells both within and surrounding the tumor in both settings. By flow cytometry, we confirmed the CAR T-cells in the CNS were primed and mostly did not express an exhaustive phenotype. In the spleen, we also found the CAR T-cells in a more naïve and central memory state. CONCLUSIONS: Our work so far has demonstrated that synNotch-CAR T-cells are able to traffic to the tumor microenvironment even in the brainstem, are primed to express the CAR, and most do not express an exhaustive phenotype. Future work will include CAR T-cell dose optimization, continued assessments of the tumor microenvironment, and investigating for antigen escape.

Perfecting CAR Engraftment to a Tee (Cell) through Characterization of Single Cell Transcriptome Product and Understanding Neurotoxicity

Background: Autologous chimeric antigen receptor T (CAR-T) cell therapies show significant clinical activity against hematologic malignancies including multiple myeloma (MM). Numerous factors influence the effectiveness of this therapeutic approach. The fitness of a CAR-T cell product is an important factor affecting T cell engraftment and persistence, a pre-requisite for effective CAR-T cell therapy. In an effort to deconstruct the cellular heterogeneity of CAR-T cell products and explore relationships between T cell states within the cellular product, gene expression and CAR-T cell engraftment following adoptive transfer, we performed single cell RNA-sequencing (scRNA-seq) on CAR-T cell products from a phase I trial of BCMA-specific CAR-T cells in relapsed/refractory MM patients that included cohorts receiving a similar CAR-T cell dose with and without preconditioning with cyclophosphamide (NCT02546167, Cohen et al, J Clin Invest 2019).Method: scRNA-seq was performed on 25 unique products with an average of 8823 cells captured per product at an average depth of 40779 reads per cell. Batch effects were controlled by integration using established metrics for quality control. The linked inference of genomic experimental relationships (LIGER) method exhibited the most effective integration of 228,752 single cells across the 25 products. Annotation was completed by comparing transcriptomes of cells to the Blueprint/ENCODE references of pure immune cells. Differential gene expression (DGE) analysis was conducted by both Wilcoxon rank sum test testing and negative binomial distribution. Gene enrichment analysis was performed by comparing DGE with the Molecular Signatures Database v7.4. Cell to cell communication utilized the KEGG signaling pathway maps and curated lists of interactions from the literature. The intercellular communication probability was estimated on the DE genes before statistically significant intercellular communications were calculated by a permutation test, with dominant senders, receivers, mediators, and influencers identified using graph theory. Patients were grouped based upon “good” or “poor” engraftment using a peak blood vector copies per cell cutoff of 10,000. Association of transcriptional variation with neurotoxicity was explored for all patients.Results: The CD4:CD8 ratio of 2.51 single cells in the data was comparable to the observed average CD4:CD8 ratio of total T cells in the product based upon flow cytometric analysis of the products at harvest. Cell annotation showed significant heterogeneity of CD4+ and CD8+ T cells with cells exhibiting a CD4 Tcm transcriptional profile comprising the largest subset of T cells within the product. DGE analysis found 205 genes that were up or down regulated between the “good” vs “poor” engraftment phenotypes with 75 genes being detected using both mathematical approaches. CAR-BCMA expression was increased in “good” engraftment groups which has not previously been shown in CAR sorted cells. Within both CD4+ and CD8+ T cell subsets, transcriptional pathways associated with the RXF5/RFXAP/RFXANK transcriptional activator complex and the IL-2/STAT5 signaling were identified as upregulated in the “good” engrafted products. Cell to cell communication analysis for both secreted signaling and cell to cell contact revealed similar ligand-receptor interaction differences between the engraftment groups. Within the neurotoxicity groups CAR-BCMA expression was not associated with either neurotoxicity or with high and low neurotoxicity effects in the product. High vs low neurotoxicity showed a shift with interferon gamma and cytokine-cytokine interactions. We also detected IL-6/JAK/STAT3 signaling activation increases in this group.Conclusion: The RFX5/RFXAP/RFXANK pathway associated with MHC class II expression and IL-2/STAT5 signaling show a significant association with engraftment of BCMA-specific CAR-T cells. Although IL-2 signaling is well known to be critical to T cell survival and a potential key driver for long-term persistence, the role of the RFX5 transcriptional activator complex in T cells, outside of its important role in regulating MHC expression, is largely unknown. Both pathways deserve further investigation. Cell to cell communication between engraftment groups suggests CD4/CD8 interactions that might be beneficial to engraftment at the product manufacturing stage. [Display omitted] DisclosuresGarfall: Amgen: Honoraria; CRISPR Therapeutics: Research Funding; GlaxoSmithKline: Honoraria; Janssen: Honoraria, Research Funding; Novartis: Research Funding; Tmunity: Research Funding. Bu: Novartis: Current Employment, Patents & Royalties: Co-inventor on patent applications. Orlando: Novartis: Current Employment. Brogdon: Novartis Institutes for Biomedical Research: Current Employment. Pruteanu-Malinici: Novartis: Current Employment. Cohen: Janssen: Consultancy; Oncopeptides: Consultancy; Genentech/Roche: Consultancy; BMS/Celgene: Consultancy; AstraZeneca: Consultancy; Novartis: Research Funding; Takeda: Consultancy; GlaxoSmithKline: Consultancy, Research Funding.

Update of CARTITUDE-1: A phase Ib/II study of JNJ-4528, a B-cell maturation antigen (BCMA)-directed CAR-T-cell therapy, in relapsed/refractory multiple myeloma.

8505 Background: JNJ-68284528 (JNJ-4528) is a chimeric antigen receptor T (CAR-T) cell therapy containing 2 BCMA-targeting single-domain antibodies. Here we present updated CARTITUDE-1 (NCT03548207) phase 1b results with longer follow-up. Methods: Pts had MM per IMWG criteria, measurable disease, received ≥3 prior regimens or were double refractory to a PI and IMiD, and received anti-CD38 antibody. Cyclophosphamide 300 mg/m2+ fludarabine 30 mg/m2 over 3 days were used for lymphodepletion. JNJ-4528 (median, 0.73x106 CAR+ viable T cells/kg) was given as a single infusion. Cytokine release syndrome (CRS) was graded by Lee et al2014 and neurotoxicity by CTCAE, v5.0 and ASTCT grading. Response was assessed per IMWG criteria. Results: As of 17 Jan 2020, median follow-up is 9 mo (3–17). Phase 1b enrollment is complete (N = 29 treated; median 5 (3–18) prior lines, 76% penta-exposed, 86% triple-refractory, 31% penta-refractory, 97% refractory to last line of therapy). Most frequent adverse events (AEs) were neutropenia (100%), CRS (93%), and thrombocytopenia (93%). Grade (Gr) ≥3 hematologic AEs were neutropenia (100%), thrombocytopenia (69%), and leukopenia (59%). 27 (93%) pts had CRS; 25 Gr 1–2, 1 Gr 3, and 1 Gr 5 (day 99 subsequent to dose-limiting toxicity of prolonged Gr 4 CRS). Median time to onset of CRS was 7 days (2–12). 4 pts had treatment-related neurotoxicity: 3 Gr 1–2 and 1 Gr 3. ORR was 100%, with 22 (76%) stringent complete responses (sCRs), 6 (21%) very good partial responses (VGPRs), and 1 (3%) PR. Median time to ≥CR was 2 mo (1–9). 26/29 pts are progression-free, with 6-mo progression-free survival rate of 93% and longest response ongoing at 15 mo. 1 death due to CRS and 1 to acute myeloid leukemia (not treatment-related) occurred during the study. All 16 pts (14 sCR, 2 VGPR) evaluable at 6 mo were minimal residual disease negative at 10−5 or 10−6. JNJ-4528 CAR+ T cell expansion peaked between day 10–14. At 6-mo individual follow-up, 22/28 pts had JNJ-4528 CAR+ T cells below the level of quantification (2 cells/µL) in peripheral blood, suggesting CAR-T persistence in peripheral blood did not seem to correlate with deepening of response. At peak expansion, preferential expansion of CD8+ CAR-T cells with a central memory phenotype was observed in peripheral blood. Conclusions: JNJ-4528 treatment led to responses in all pts. These responses were early, deep, and durable at a low dose of CAR-T cells with 26/29 (90%) pts progression free at median 9-mo follow-up. CRS was manageable in most pts, supporting outpatient dosing. Clinical trial information: NCT03548207 .

Chimeric antigen receptor T-cell therapies: Optimising the dose.

Lymphocytes such as T-cells can be genetically transduced to express a synthetic chimeric antigen receptor (CAR) that re-directs their cytotoxic activity against a tumour-expressed antigen of choice. Autologous (patient-derived) CAR T-cells have been licensed to treat certain relapsed and refractory B-cell malignancies, and numerous CAR T-cell products are in clinical development. As living gene-modified cells, CAR T-cells exhibit unique pharmacokinetics, typically proliferating within the recipient during the first 14 days after administration before contracting in number, and sometimes exhibiting long-term persistence. The relationship between CAR T-cell dose and exposure is highly variable, and may be influenced by CAR design, patient immune function at the time of T-cell harvest, phenotype of the CAR T-cell product, disease burden, lymphodepleting chemotherapy and subsequent immunomodulatory therapies. Recommended CAR T-cell doses are typically established for a specific product and indication, although for some products, stratification of dose based on disease burden may mitigate toxicity while maintaining efficacy. Re-evaluation of CAR T-cell dosing may be necessary following changes to the lymphodepleting regimen, for different disease indications, and following significant manufacturing changes, if product comparability cannot be demonstrated. Dose escalation trials have typically employed 3 + 3 designs, although this approach has limitations, and alternative phase I trial designs may facilitate the identification of CAR T-cell doses that strike an optimal balance of safety, efficacy and manufacturing feasibility.

Intravital imaging reveals synergistic effect of CAR T-cells and radiation therapy in a preclinical immunocompetent glioblastoma model

ABSTRACT Recent advances in novel immune strategies, particularly chimeric antigen receptor (CAR)-bearing T-cells, have shown limited efficacy against glioblastoma (GBM) in clinical trials. We currently have an incomplete understanding of how these emerging therapies integrate with the current standard of care, specifically radiation therapy (RT). Additionally, there is an insufficient number of preclinical studies monitoring these therapies with high spatiotemporal resolution. To address these limitations, we report the first longitudinal fluorescence-based intravital microscopy imaging of CAR T-cells within an orthotopic GBM preclinical model to illustrate the necessity of RT for complete therapeutic response. Additionally, we detail the first usage of murine-derived CAR T-cells targeting the disialoganglioside GD2 in an immunocompetent tumor model. Cell culture assays demonstrated substantial GD2 CAR T-cell-mediated killing of murine GBM cell lines SB28 and GL26 induced to overexpress GD2. Complete antitumor response in advanced syngeneic orthotopic models of GBM was achieved only when a single intravenous dose of GD2 CAR T-cells was following either sub-lethal whole-body irradiation or focal RT. Intravital microscopy imaging successfully visualized CAR T-cell homing and T-cell mediated apoptosis of tumor cells in real-time within the tumor stroma. Findings indicate that RT allows for rapid CAR T-cell extravasation from the vasculature and expansion within the tumor microenvironment, leading to a more robust and lasting immunologic response. These exciting results highlight potential opportunities to improve intravenous adoptive T-cell administration in the treatment of GBM through concurrent RT. Additionally, they emphasize the need for advancements in immunotherapeutic homing to and extravasation through the tumor microenvironment.

Mathematical deconvolution of CAR T-cell proliferation and exhaustion from real-time killing assay data.

Chimeric antigen receptor (CAR) T-cell therapy has shown promise in the treatment of haematological cancers and is currently being investigated for solid tumours, including high-grade glioma brain tumours. There is a desperate need to quantitatively study the factors that contribute to the efficacy of CAR T-cell therapy in solid tumours. In this work, we use a mathematical model of predator–prey dynamics to explore the kinetics of CAR T-cell killing in glioma: the Chimeric Antigen Receptor T-cell treatment Response in GliOma (CARRGO) model. The model includes rates of cancer cell proliferation, CAR T-cell killing, proliferation, exhaustion, and persistence. We use patient-derived and engineered cancer cell lines with an in vitro real-time cell analyser to parametrize the CARRGO model. We observe that CAR T-cell dose correlates inversely with the killing rate and correlates directly with the net rate of proliferation and exhaustion. This suggests that at a lower dose of CAR T-cells, individual T-cells kill more cancer cells but become more exhausted when compared with higher doses. Furthermore, the exhaustion rate was observed to increase significantly with tumour growth rate and was dependent on level of antigen expression. The CARRGO model highlights nonlinear dynamics involved in CAR T-cell therapy and provides novel insights into the kinetics of CAR T-cell killing. The model suggests that CAR T-cell treatment may be tailored to individual tumour characteristics including tumour growth rate and antigen level to maximize therapeutic benefit.

Efficiency and safety of autologous chimeric antigen receptor T-cells therapy used for patients with lymphoma: A systematic review and meta-analysis.

Chimeric antigen receptor (CAR) T-cell therapy has produced promising response rates in patients with B cell malignancies. However, previous meta-analyses have demonstrated that CAR T-cell efficacy is unsatisfactory in patients with lymphoma unlike in patient with other hematological malignancies, but these studies included insufficient numbers of studies and patients with lymphoma. Furthermore, clinicians are interested in the effects of infusion dose, CAR structure, interleukin-2 (IL-2), and conditioning therapy regimen. All clinical trials administering autologous CAR T-cell therapy in lymphoma patients were searched in medical databases. A traditional meta-analysis was performed to assess the safety and efficacy of CAR T-cells in lymphoma treatment. Subgroup analysis was performed to determine the relationships between potential factors and efficacy. The best overall response rate (ORR), 6 month ORR (6m ORR), and severe cytokine release syndrome (sCRS) rate were calculated by Stata 14.0. A total of 411 patients across all the studies were included. Our analysis showed a best ORR of 0.71, a 6m ORR of 0.63, and an overall CRS (grade ≥ 3) rate of 0.18. The subgroup analysis showed that increased response rates and reduced CRS (grade ≥ 3) rates were associated with a low dose of CAR T-cells. No IL-2 administration and the use of a fludarabine-containing lymphodepletion regimen led to improved efficacy, while anti-CD19 CAR T cells led to a more successful outcome than anti-CD20 CAR T cells. In addition, 2nd- and 3rd-generation CAR T cells exhibited increased effectiveness in clinical studies, and no significant effect diversity was found between the 2nd- and 3rd-generation CAR T cells. sCRS was associated with a high dose of infused CAR T cells when IL-2 and fludarabine were excluded from the positive factors for sCRS. CAR T cells are promising in the treatment of relapsed or refractory lymphoma. Doses lower than 10/m, no IL-2 administration, fludarabine administration, and anti-CD19 CAR T cells were related to improved efficacy and safety.

Low Dose of Human scFv-Derived BCMA-Targeted CAR-T Cells Achieved Fast Response and High Complete Remission in Patients with Relapsed/Refractory Multiple Myeloma

▪Introduction: B Cell Mature Antigen (BCMA)-targeted chimeric antigen receptor T (CAR-T) cell therapy emerges as promising treatment for patients with relapse/refractory multiple myeloma (RRMM). Previous studies indicate patients who receive high-dose CAR-T cells may achieve better remission but have worse adverse events, like cytokine release syndrome (CRS). To solve this dilemma, we have developed novel autologous CAR-T therapeutics CT053 that are genetically modified T cells comprising an extracellular anti-BCMA human scFv and an intracellular 4-1BB costimulatory motif connected to a CD3-zeta T cell activation domain.Methods: A multi-center investigator-initiated clinical study is designed to evaluate CT053 in patients with RRMM who have failed in the prior treatment with ≥2 regimens, including a proteasome inhibitor, an immunomodulatory agent, and anti-CD38 monoclonal antibody. All patients have ≥50% BCMA expression on malignant cells. Patients are subjected to the lymphodepletion with 20-25 mg/m2 fludarabine and 300-500 mg/m2 cyclophosphamide daily for 2-4 days prior to receiving single-dose infusion of CT053 CAR-T cells. In case of progressive disease, patient may be dosed again on basis of investigators' evaluation of the disease status, BCMA expression and CAR-T persistence. Most enrolled patients received a single dose of 1.5 x 108 cells, except for 1 patient who received 0.5 x 108 cells and 1 patient who was infused with 1.8 x 108 cells. The primary outcome measure is incidence of adverse events (AEs), including dose-limiting toxicities (DLTs) and CAR T related AEs. Additional outcome measures include clinical response assessed according to the IMWG Uniform Response Criteria for Multiple Myeloma, overall and progression-free survival, pharmacokinetics and pharmacodynamic of CT053.Results: The study was performed in compliance with the declaration of Helsinki. As of the data cut-off date (July 10th, 2018), 16 patients (median 55 [39 to 67] years old) with a median of 3.9 (0.4 to 16.7) years since MM diagnosis, were infused with CT053. Patients had a median of 4 prior different regimens (range 2 to 10), and 56% (9/16) patients received prior autologous or allogeneic stem cell transplant.Among 16 patients, no neurotoxicity and no dose-limiting toxicities (DLT) were observed. The most common grade≥3 CAR-T related AEs were 3 thrombocytopenia (19%), 3 leukopenia (19%), 2 anemia (13%), 2 neutropenia (13%), 2 fever (13%) (Figure 1A). CRS was reported in 3 patients, including 1 Grade 3, 1 Grade 2 and 1 Grade 1, who had rapid recovery after Tocilizumab administration.13/16 patients were eligible for initial evaluation of early clinical response with a median observation period of 8 (4 to 36) weeks. Overall response rate (ORR) in 13/13 patients was 100% post treatment. 12/13 patients (92%) quickly achieved partial response (4 PR), very good PR (6 VGPR), and complete response (2 CR) within 4 weeks post single-dose infusion (Figure 1B). 5/12 patients (42%) who were dosed at ≥1.5 x 108 CT053 CAR-T cells obtained CR at a median of 8 weeks post treatment. Durable responses from 4 weeks towards the data cut-off date were found in 12/13 patients (92%). One relapse from VGPR by the Week 12 was reported in a patient who had aggressive RRMM at enrollment and received the reduced dose of lymphodepletion regimen at 19 mg/m2 fludarabine and 192 mg/m2 cyclophosphamide for 2 days prior to CT053 infusion. Because positive BCMA expression on malignant cells was verified at relapse, the patient was re-dosed with CT053 at the Week 16 and subjected to the further evaluation.All patients had detectable CAR-T expansion from Day 3 post CT053 infusion. Expansion peaks were found on Day 7 (5/13), Day 14 (6/13) and Day 21 (2/13). 11/13 patients had notable persistence of CT053 CAR-T cells up to 4-6 months. The only relapsed patient had the lowest CAR-T expansion peak among 13 patients, indicating the potential correlation between CAR-T expansion and response outcome.Conclusions: Data from this early-stage clinical study showed the unparalleled safety and efficacy of CT053 CAR-T cells. Major AEs were transient, manageable, and reversible. 100% ORR in 13/13 evaluable patients were reported post single-dose infusion of 0.5~1.8 x 108 cells. 5/12 patients who were dosed at ≥1.5 x 108 CAR-T cells rapidly achieved durable CR at median of 8 weeks, suggesting CT053 could be developed as competitive therapeutics to treat patients with RRMM. DisclosuresRuan:CARsgen Therapeutics: Employment. Xiao:CARsgen Therapeutics: Employment, Equity Ownership. Wang:CARsgen Therapeutics: Employment, Equity Ownership. Li:CARsgen Therapeutics: Employment, Equity Ownership.

Anti-CD 19 and Anti- CD 20 Chimeric Antigen Receptor-Modified T Cells for B-Cell Malignancies: A Systematic Review and Meta-Analysis

Background:Chimeric antigen receptor (CAR) modified T cells targeting CD19 and CD20 have shown activity in Phase I, II trials of patients with hematological malignancies. CD19 and CD20 targeted CAR constructs from several different institutions have demonstrated consistently high anti-tumor efficacy in children and adults with relapsed B-cell acute lymphoblastic leukemia (B-ALL), chronic lymphocytic leukemia (CLL) and B-cell non-Hodgkin lymphoma (B-NHL). We conducted a systematic review and meta-analysis of all published clinical trials studying the role of efficacy as well as safety of CD-19 and CD-20 CAR-T therapy for B-cell hematologic malignancies.Methods:Literature search was performed using MEDLINE (Ovid SP and PubMed), EMBASE, The Cochrane Library, Scopus and Web of Science. We conducted meta-analysis using random effects model using Comprehensive Metaanalysis 3.0. Heterogeneity was assessed using Q-statistic and it was quantified using I2statistic.Results:After a comprehensive literature search 4476 studies were identified and finally 15 eligible studies involving 121 patients were included in the final systematic review. The infused CAR T-cell dose was in the range of 0.76 x 106 to 3 x 107 cells/kg in seven trials and in the range of 0.8 x 107 cells to 3.3 x 109 cells/m2in 6 trials. Among 106 patients, the overall response to treatment after CAR T-cell infusion were 33% complete remission (CR), 30 % partial remission (PR), 21% stable disease (SD), and 8% progressive disease (PD). Three studies described response to immunotherapy as minimal residual disease negative (MRD-) and as no evidence of disease (NED) and after including it, the overall CR was 38%. Major adverse events included fever (38%), hypotension (23%), chills (29%), rigor (28%), fatigue 17% and dyspnea 10%. One patient died from cytokine release syndrome, which is potentially serious complication. Neurological symptoms require prompt recognition and management.Conclusion:CAR T cell therapy is a promising treatment for refractory and relapsed hematological malignancies. The durable responses of CAR T cell therapy help integrate it in standard treatment protocols. Patients who are refractory to standard salvage chemotherapy or relapse after allo - HSCT have overall poor prognosis and can potentially achieve remission again with CAR T cell therapy. DisclosuresMcBride:Sanofi: Research Funding. Anwer:Seattle Genetics: Other: Advisory Board Participant; Incyte: Speakers Bureau.