scholarly journals CD19-CAR Therapy Using Naive/Memory or Central Memory T Cells Integrated into the Autologous Stem Cell Transplant Regimen for Patients with B-NHL

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 610-610 ◽  
Author(s):  
Leslie Popplewell ◽  
Xiuli Wang ◽  
Suzette Blanchard ◽  
Jamie Wagner ◽  
Araceli Naranjo ◽  
...  
Keyword(s):  
T Cells ◽  
Stem Cell ◽  
T Cell ◽  
Research Funding ◽  
Memory T Cells ◽  
Central Memory ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

Abstract Autologous stem cell transplantation (ASCT) remains an important consolidative therapy for patients with recurrent non-Hodgkin lymphoma (NHL), but is limited by the high incidence of NHL relapse. We report a Phase I clinical trial of ASCT followed by CD19-specific CD28-costimulatory chimeric antigen receptor (CD19:28z-CAR) T cells, with the goal of reducing NHL relapse rates. Safety and feasibility were the primary objectives, with CAR T cell persistence and expansion in the myeloablative ASCT setting as secondary objectives. This study examines safety and feasibility for two manufacturing platforms that differed in the T cell subset composition used for CAR engineering. Initially, the T cell population for CAR transduction was central memory (Tcm)-enriched: participants' peripheral blood mononuclear cells (PBMC) were depleted for CD14+ monocytes, CD25+ Tregs, and CD45RA+ naïve and stem-memory T cells, after which they were selected for CD62L+ Tcm (Wang et al. Blood;127:2980). Based on comparative preclinical data, a second arm was added to the trial to evaluate a Tn/mem-derived manufacturing platform that enriched central memory, naïve, and stem memory T cells (no CD45RA+ depletion). Either Tcm- or Tn/mem-enriched T cells were activated with CD3/CD28 beads, transduced with lentiviral vector encoding the CD19:28z-CAR, and expanded ex vivo. This phase I trial used the toxicity equivalence range design (Blanchard and Longmate. Contemp Clin Trials; 32;114) with an equivalence range for DLTs of 0.20-0.35 and a target toxicity rate of 0.25. The first 3 participants on each arm were followed one at a time, with later accrual in cohorts of 3. Twenty-three participants underwent ASCT and received CD19:28z-CAR T cells 2 days post stem cell infusion at the assigned dose level (DL): 17 on the Tcm arm (DL 50 million [M] CAR+ T cells [n=3], 200 M [n=5], 600 M [n=9]); 6 on the Tn/mem arm (DL 200 M). Participants were followed for dose limiting toxicity (DLT) for 28 days. Table 1 shows results by arm and DL. Both arms demonstrated safety and feasibility. There was no delayed hematopoietic reconstitution on either arm. On the Tcm arm, the only DLT was at DL 600 M (1 of 9 at 600 M). The Tn/mem arm was opened at 200 M and 6 participants were treated with no DLTs. The dose was not escalated as the protocol management team had seen activity at the 200M level in 2 other trials using the Tn/mem product. Tcm Arm: Fourteen of 17 participants (82%) had a diagnosis of diffuse large B-cell lymphoma (DLBCL) and 3 had mantle cell lymphoma. The mean age of the participants on the Tcm arm was 57 (35-75). The median number of prior chemotherapy regimens was 2 (1-5). The median progression-free survival (PFS) was 34.6 months 95% CI [21.8, undefined]. Seven of 17 participants (41%) have progressed, 1 died in remission of unrelated intracranial hemorrhage (6%), 7 (41%) remain in CR and are still in follow-up, and 2 are lost to follow-up (12%). All 17 participants achieved a CR or a continuing CR after ASCT and T cells. Tn/mem arm: Five of 6 participants (83%) had a DLBCL diagnosis, and 1 was NHL not otherwise specified. The mean age of the participants was 50 (40-72). The median number of prior chemotherapy regimens was 2.5 (1-3). The median follow-up time for the Tn/mem arm was 12 months, with median PFS not yet reached. One of 6 (17%) has progressed, 4 (66%) remain in CR and are still in follow-up, and 1 is lost to follow-up (17%). Five of 6 (83%) participants achieved a best response of CR or continuing CR after therapy. Several differences were observed between the manufacturing platforms. Since the Tn/mem production platform has fewer depletion steps, it resulted in a higher product yield, which shortened the ex vivo expansion period by 4.1 days (95% CI [1.5%, 6.6%]) from 18.9 days (15-24) for Tcm to 14.8 days (12-18) for Tn/mem (P<0.005). Notably in the ASCT minimal disease burden setting, the Tn/mem-derived CD19:28z-CAR T cell products exhibited significantly higher in vivo CAR T cell expansion compared to Tcm products at the 200M DL (Figure 1). We conclude that although both Tcm- and Tn/mem-enriched CD19CAR T cell therapies are safe, the Tn/mem product is more promising due to its 1) shorter production time, 2) higher cell yield, and 3) better in vivo expansion, despite the low antigen drive in these patients post-salvage and ASCT therapy. Longer follow-up for the 2-year PFS secondary objective will indicate if improved Tn/mem expansion impacts tumor control. Disclosures Wang: Mustang Therapeutics: Other: Licensing Agreement, Patents & Royalties, Research Funding. Budde:Mustang Therapeutics: Consultancy, Other: Licensing Agreement, Patents & Royalties, Research Funding. Brown:Mustang Therapeutics: Consultancy, Other: Licensing Agreement, Patents & Royalties, Research Funding. Forman:Mustang Therapeutics: Other: Licensing Agreement, Patents & Royalties, Research Funding.

scholarly journals B Cell Maturation Antigen-Specific CAR T Cells for Relapsed or Refractory Multiple Myeloma: A Meta-Analysis

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3113-3113 ◽  
Author(s):  
Nico Gagelmann ◽  
Francis Ayuketang Ayuk ◽  
Djordje Atanackovic ◽  
Nicolaus Kroeger
Keyword(s):  
T Cells ◽  
T Cell ◽  
High Risk ◽  
Research Funding ◽  
Response Rates ◽  
Overall Response ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

Background Cellular immunotherapies represent an enormously promising strategy for relapsed/refractory multiple myeloma (RRMM). Chimeric antigen receptor (CAR) T cells targeting B cell maturation antigen (BCMA) have shown impressive results in early-phase clinical studies. Here, we summarize the current body of evidence on the role of anti-BCMA CAR T cell therapy for RRMM. Methods We performed a systematic literature review to identify all publicly available prospective studies. We searched Medline, Cochrane trials registry, and www.clinicaltrials.gov. To include the most recent evidence, meeting abstracts from international hematology congresses were added. A conventional meta-analysis was conducted using meta and metafor packages in R statistical software. Pooled event rates and 95% confidence intervals (CIs) were calculated using the inverse variance method within a random-effects framework. Main efficacy outcomes were overall response, complete response (CR), and minimal residual disease (MRD). Furthermore, relapse rates, progression-free survival, and overall survival were evaluated. In terms of safety, outcomes were cytokine release syndrome (CRS), neurotoxicity, and hematologic toxic effects. Results Fifteen studies comprising a total of 285 patients with heavily pretreated RRMM were included in quantitative analyses. Patients received a median of seven prior treatment lines (such as proteasome inhibitors, immunomodulatory drugs, monoclonal antibodies, stem cell transplantation) which included autologous stem cell transplantation in 90% of patients. The median age of patients was 59 years and median follow-up duration ranged from 1.1 to 11.3 months. Most studies used 4-1BB (or CD137), a member of the TNF receptor superfamily, as an activation-induced T-cell costimulatory molecule. Most studies used fludarabine and cyclophosphamide for lymphodepletion while one study used busulfan and cyclophosphamide and one study used cyclophosphamide only. Most studies used the former Lee criteria for CRS grading. Anti-BCMA CAR T cells resulted in a pooled overall response of 82% (95% CI, 74-88%). The pooled proportion of CR in all evaluable patients was 36% (95% CI, 24-50%). Within responders, the pooled proportion of MRD negativity was 77% (95% CI, 67-85%). Higher dose levels of infused CAR+ cells were associated with higher overall response rates resulting in a pooled proportion of 88% (95% CI, 78-94%). In addition, peak CAR T cell expansion appeared to be associated with responses.The presence of high-risk cytogenetics appeared to be associated with lower overall response rates resulting in a pooled proportion of 68% (95% CI, 47-83%). The presence of extramedullary disease at time of infusion did not influence outcome and was associated with similar response rates compared with RRMM patients who did not have extramedullary disease, resulting in a pooled proportion of 78% (95% CI, 47-93%). The pooled relapse rate of all responders was 45% (95% CI, 27-64%) and the median progression-free survival was 10 months. In terms of overall survival, pooled survival rates were 84% (95% CI, 60-95%) at last follow-up (median, 11 months). In terms of safety, the pooled proportion of CRS of any grade was 69% (95% CI, 51-83%). Notably, the pooled proportions of CRS grades 3-4 and neurotoxicity were 15% (95% CI, 10-23%) and 18% (95% CI, 10-31%). Peak CAR T cell expansion appeared to be more likely in the setting of more severe CRS in three studies. Most hematologic toxic effects of grade 3 or higher were neutropenia (85%), thrombocytopenia (70%), and leukopenia (60%). Conclusion Anti-BCMA CAR T cells showed high response rates, even in high-risk features such as high-risk cytogenetics and extramedullary disease at time of CAR T cell infusion. Toxicity was manageable across all early-phase studies. However, almost half of the patients who achieved a response eventually relapsed. Larger studies with longer follow-up evaluating the association of response and survival are needed. Disclosures Ayuk: Novartis: Honoraria, Other: Advisory Board, Research Funding. Kroeger:Medac: Honoraria; Sanofi-Aventis: Honoraria; Neovii: Honoraria, Research Funding; Riemser: Research Funding; JAZZ: Honoraria; Novartis: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; DKMS: Research Funding.

scholarly journals Response to Anti-Bcma CAR T Cell Therapy Correlates with T Cell Exhaustion and Activation Status in T Cells at Baseline in Myeloma

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1909-1909 ◽  
Author(s):  
Meng Wang ◽  
Iulian Pruteanu ◽  
Adam D. Cohen ◽  
Alfred L. Garfall ◽  
Lifeng Tian ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Board Of Directors ◽  
Research Funding ◽  
Precursor Cells ◽  
Central Memory ◽  
Advisory Committees ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

Despite intense efforts, multiple myeloma remains incurable in most patients with the standard of care therapies. The plasma cell surface receptor B cell maturation antigen (BMCA) is highly expressed by myeloma cells and we recently demonstrated that 12 out of 25 heavily pretreated myeloma patients achieved a partial response or better after anti-BCMA CAR T cell treatment (VGPR, n=5; CR, n=1; sCR, n=1; Cohen et al., 2019, JCI 129(6):2210). To better understand the biological basis of this therapy, we identified key correlates of response using the pre-manufacturing apheresed T cells, the infusion product, and post-infusion T cells from the 25 patients in this cohort. As reported before, the disease characteristics, tumor burden, and CAR transduction efficiency did not correlate with therapy response. CAR T cell expansion, measured by the area under the curve of CAR qPCR in the first 21 days (AUC[0-21]), was highest in responding, lowest in non-responding patients (Jonckheere-Terpstra test, JT = 38, p=1.8x10^-6)(Fig.1A,B). Soluble BCMA, a biomarker of disease burden, shows a similar trend with response (Jonckheere-Terpstra test, JT = 54, p=1.2x10^-4). Furthermore, AUC[0-21] for CAR T cell expansion and soluble BCMA decline also strongly correlated (Spearman's rank correlation test, rho=0.82; p=2.41x10^-6), underscoring the quantitative relationship between CAR T cell expansion and tumor reduction. We have previously shown that response to CAR T cell therapy in CLL is largely determined by T cell memory function. To find if this extends to myeloma, we immunophenotyped apheresed T cells (or CAR-T precursor cells) and infusion product from the 25 patients. Phenotypically distinct T cell subpopulations were identified using shared-nearest-neighbor clustering method (PMID: 31178118) and their correlation with response to CAR T cell treatment was evaluated. This analysis revealed that among CD4+ and CD8+ CAR-T precursor cells, subpopulations representing naive and central memory T cells were enriched in T cells from responding patients, while non-responders displayed a distinctly activated effector phenotype at baseline. Additional analyses showed that apheresed CD8+ and CD4+ T cells from responder patients were non-cycling, granzyme B-negative, CTLA4[low] but otherwise largely immune checkpoint inhibitor-negative. CD8+ CAR-T precursor cells isolated from non-responders exhibited high expression levels of TIM3 or LAG3, and/or granzyme B, but not PD1, CTLA4, CD45RO or CD27. These data confirm the high activation, potential exhaustion and end-stage differentiation state of CAR-T precursor cells in this group. Similar analyses of infusion product CAR T cells did not reveal subpopulations associated with response. Clustering analysis of CD8+ CAR T cells within 20 days after infusion revealed a BCMA CAR-expressing cluster enriched in responding patients: a non-cycling, negatively regulated, Eomes-expressing central memory subset (cluster 0; Fig. 1E). Non-responding patients CAR-T cells displayed high levels of granzyme B and PD1 expression but were otherwise devoid of signs of activation (cluster 8; Fig. 1F). Furthermore, the abundance of CD8+ CAR-T cells with cluster 0 and 8 phenotype correlated significantly with in vivo expansion (AUC[0-21]; Fig. 1C). Four patients with a sufficiently high proportion of CAR expressing cells were phenotyped up to 125 days post-infusion. This analysis showed that the highly activated CAR T cell clusters 2 and 5 dominated at early phases post infusion but was rapidly replaced by non-cycling CAR T cells with downregulated CTLA4 and LAG3 but maintained expression of PD1 and TIM3 (cluster 0; Fig. 1D). Patient 27 with VGPR had a prominent effector population four months after infusion. BCMA-redirected CD4+ CAR T cells showed an enrichment of central memory phenotype CAR T cells in responding patients early after infusion, with high expression of Eomes, TIM3, and other immune checkpoint inhibitor molecules. This cluster also dominated the CD4 T cell repertoire in the first four months after infusion in the four responding patients. In conclusion, our data suggest that strategies to promote expression of Eomes and central memory function and reduce exhaustion in BCMA CAR T cells will enhance clinical activity. Further, these results underscore the "self-sustaining" feature of successful CAR T cell therapies in myeloma. Disclosures Pruteanu: Novartis: Employment. Cohen:Poseida Therapeutics, Inc.: Research Funding. Garfall:Tmunity: Honoraria, Research Funding; Amgen: Research Funding; Novartis: Patents & Royalties: inventor on patents related to tisagenlecleucel (CTL019) and CART-BCMA, Research Funding; Janssen: Research Funding; Surface Oncology: Consultancy. Lacey:Novartis: Patents & Royalties: Patents related to CAR T cell biomarkers; Tmunity: Research Funding; Novartis: Research Funding. Fraietta:Tmunity: Research Funding; Cabaletta: Research Funding; LEK Consulting: Consultancy. Brogdon:Novartis: Employment. Davis:Tmunity: Research Funding; Cabaletta: Research Funding. Levine:Tmunity Therapeutics: Equity Ownership; Avectas: Membership on an entity's Board of Directors or advisory committees; Vycellix: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy; Novartis: Consultancy, Patents & Royalties, Research Funding; Cure Genetics: Consultancy; Incysus: Membership on an entity's Board of Directors or advisory committees; Brammer Bio: Membership on an entity's Board of Directors or advisory committees; CRC Oncology: Consultancy. Milone:Novartis: Research Funding; Novartis: Patents & Royalties: patents related to tisagenlecleucel (CTL019) and CART-BCMA. Stadtmauer:Janssen: Consultancy; Tmunity: Research Funding; Amgen: Consultancy; Abbvie: Research Funding; Novartis: Consultancy, Research Funding; Takeda: Consultancy; Celgene: Consultancy. June:Novartis: Research Funding; Tmunity: Other: scientific founder, for which he has founders stock but no income, Patents & Royalties. Melenhorst:National Institutes of Health: Research Funding; Parker Institute for Cancer Immunotherapy: Research Funding; Novartis: Research Funding, Speakers Bureau; Colorado Clinical and Translational Sciences Institute: Membership on an entity's Board of Directors or advisory committees; Stand Up to Cancer: Research Funding; Incyte: Research Funding; IASO Biotherapeutics, Co: Consultancy; Simcere of America, Inc: Consultancy; Shanghai Unicar Therapy, Co: Consultancy; Genentech: Speakers Bureau.

scholarly journals A Novel Second Generation CD19 CAR for Therapy of High Risk/Relapsed Paediatric CD19+ Acute Lymphoblastic Leukaemia and Other Haematological Malignancies: Preliminary Results from the Carpall Study

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 4026-4026
Author(s):  
Sara Ghorashian ◽  
Anne Marijn Kramer ◽  
Sarah Jayne Albon ◽  
Catherine Irving ◽  
Lucas Chan ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Research Funding ◽  
Memory T Cells ◽  
Transduction Efficiency ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Post Infusion ◽  
Equity Ownership

Abstract Introduction: Recent clinical trials with T cells engineered to express 2nd generation CD19 chimeric antigen receptors (CARs) unprecedented anti-leukemic responses. We have developed a novel CD19CAR with a new scFv in the 41BBz format (CAT-41BBz CAR) which confers enhanced cytotoxicity and cytokine secretion in response to stimulation with CD19+ targets in vitro as well as equivalent in vivo anti-tumour efficacy to the FMC63 41BBZ CAR in use in clinical studies. We have designed, optimized and validated GMP-grade CAR T cell production using this novel CAR. Based on these data, we have recently initiated a Phase I clinical study (CARPALL) of this novel CAR in pediatric patients with relapsed ALL and other CD19+ hematological malignancies to determine the safety profile and durability of responses to CD19CART therapy. This will be critical in determining whether CD19CAR T cells are best used as a stand-alone therapy or as a bridge to stem cell transplant (SCT). Methods: We initially optimized our GMP production methodology in terms of activation method, cytokine milieu and expansion conditions on healthy donor peripheral blood mononuclear cells (PBMCs) to give optimal transduction efficiency and preserve early memory subsets within the CAR T cell product. We have subsequently validated this methodology using unstimulated leucaphereses from 5 lymphopenic patients with ALL. PBMCs were activated with anti-CD3/CD28 microbeads (Dynabeads CTS) and then lentivirally transduced with the CAT CAR vector. T cells were then expanded in the WAVE bioreactor before bead removal on a magnetic system and cryopreservation. Patients on study receive lymphodepletion with fludarabine and cyclophosphamide followed by a single dose of 106 CAR+ T cells/kg and are then monitored as an in-patient for 14 days post infusion for toxicities such as cytokine release syndrome or neurotoxicity. The primary end-points of the study are toxicity and the proportion of patients achieving molecular CR at 1 month post CD19CAR T cell infusion. Following this, patients undergo intensive monitoring of disease status for a total of 2 years post infusion. To determine the durability of responses, patients achieving a molecular CR will be monitored closely for the re-emergence of molecular level disease without additional consolidative therapy or SCT Results: We were able to generate the target dose of 1x106 CAR+ T cells/kg in 6 of 7 production runs (involving 2 healthy donors and 5 patients) to date, all of which met sterility release criteria. Transduction efficiency was on average 37% (range 7-84%, see table 1). Mean viral copy was 4.2 (range 1.2-5.8). Memory T cells of stem cell-like phenotype (CAR+ CCR7+ CD45RA+ CD95+ CD127+) formed a mean of 9% (range 0-31%), central memory T cells (CAR+ CCR7+ CD45RA-) formed a mean of 43% (range 16-70%) and effector memory T cells formed a mean of 31% (range 0-77%) of the final CAR T cell product. The percentage of CAR T cells expressing dual exhaustion markers (TIM3+ PD-1+) was on average 5% (range 2-8%). So far 2 patients have been treated. Conclusions We have optimized and successfully validated a robust GMP production method for CD19CAR T cells lentivirally transduced with a novel CD19CAR. Preliminary results of therapy with CAT-41BBz CAR T cells in initial patients on the clinical study will be presented. Disclosures Qasim: Autolus: Consultancy, Equity Ownership, Research Funding; Cellectis: Research Funding; Calimmune: Research Funding; Catapult: Research Funding. Pule:Autolus Ltd: Employment, Equity Ownership, Research Funding; UCL Business: Patents & Royalties; Amgen: Honoraria; Roche: Honoraria.

scholarly journals Lenalidomide Enhances the Function of CS1 Chimeric Antigen Receptor Redirected-T Cells Against Multiple Myeloma

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 812-812 ◽  
Author(s):  
Xiuli Wang ◽  
Ryan Urak ◽  
Miriam Walter ◽  
Lihong Weng ◽  
Laura Lim ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
T Cells ◽  
T Cell ◽  
Memory T Cells ◽  
Central Memory ◽  
Central Memory T Cells ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

Abstract Multiple myeloma (MM) is an incurable malignancy of plasma cells even with great advances in treatment. Chimeric Antigen Receptor (CAR) directed T cell therapy, which can specifically recognize tumor associated antigens and kill tumor cells in an MHC independent manner, is a promising approach for hematological malignancy. There are several candidate antigens for CAR T cell targeting of multiple myeloma, including BCMA and CS1. Our goal is to develop novel CARs for the treatment of MM and explore the potential benefits of combinatorial therapy of CAR T cells and immunomodulatory drugs (IMiDs) such as lenalidomide. In the present study, we redirected central memory T cells to express second-generation CARs specific for either CS1 or BCMA that incorporate CD28 signaling moieties. Central memory T cells were activated by CD3/CD28 bead stimulation, transduced with lentivirus encoding the CAR construct, and expanded ex vivo. The engineered and expanded CS1 and BCMA CAR T cells exhibited similar phenotypes and comparable in vitro effector function. However, once adoptively transferred into MM tumor-bearing NOD/Scid IL2RγCnull (NSG) mice by intravenous injection of 1x10^6 CAR T cells, CS1 CAR T cells exhibited superior antitumor activity over BCMA CART cells and significantly prolonged mouse survival (P<0.01). To further improve the anti-MM activity of CAR T cell therapy, we investigated the effects of lenalidomide on CS1 CAR T cell function against MM. Central memory T cells were activated and transduced with lentivirus encoding CS1 CAR and then expanded in vitro in the presence of 0, 1 or 10mM lenalidomide for 3-4 weeks and then effector function was evaluated. We found that CD8+ CAR T cells were preferentially expanded over CD4+ CAR T cells in a dose-dependent manner. Lenalidomide-treated CAR T cells secreted higher levels of Th1 cytokines such as IFN-gamma, TNF-alpha, and IL-2, but reduced Th2 cytokines such as IL-4 and IL-10 upon antigen stimulation as compared with untreated CAR T cells. Meanwhile we observed that lenalidomide greatly improved the maintenance of T cell memory markers (CD62L, CD28, and CD27) in the culture and enhanced the formation of immune synapses between CAR T cells and MM cells. RNA-seq analysis revealed that more than 600 genes were differentially expressed among the lenalidomide treated and un-treated CD8+CAR+ T cells. Among those, expression of immune synapse related genes such as cell junction and biological assembly is significantly increased with lenalidomide treatment. Moreover, lenalidomide results in elevated gene transcrips characteristic of memory, homing and cytolytic function of CAR T cells. To test the synergistic effects, MM bearing mice were treated with a single infusion of 1x10^6 CS1 CAR T cells (i.v) on day 0 and/or 5-7.5mgkg-1 of lenalidomide daily (i.p.) initiating on day 0 for 30 days. CS1 CAR T cells and lenalidomide exhibited synergistic anti-MM activity in vivo when MM mice received combinatorial treatment. The combination therapy significantly inhibited tumor growth in vivo, prolonged mouse survival (P<0.01) and improved CAR T cell persistence in mice as compared to single-agent treatment. Taken together, these findings indicate that lenalidomide plays a co-stimulatory role in immune modulation of CAR T cells and strengthens the anti-tumor activity of CS1 CAR T cells in vivo. Rational combination of these immunotherapeutic regimens is an effective strategy and the planned clinical trial will use a combination of lenalidomide and CS1 CAR T cells for increasing treatment efficacy. Disclosures No relevant conflicts of interest to declare.

scholarly journals Simultaneous Targeting of CD19 and CD22: Phase I Study of AUTO3, a Bicistronic Chimeric Antigen Receptor (CAR) T-Cell Therapy, in Pediatric Patients with Relapsed/Refractory B-Cell Acute Lymphoblastic Leukemia (r/r B-ALL): Amelia Study

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 279-279 ◽  
Author(s):  
Persis J Amrolia ◽  
Robert Wynn ◽  
Rachael Hough ◽  
Ajay Vora ◽  
Denise Bonney ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Phase I ◽  
Research Funding ◽  
Advisory Board ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Equity Ownership

Abstract Introduction CAR T-cell therapies directed against CD19 or CD22 antigens have shown significant activity in pediatric patients with r/r B-ALL. Whilst complete response (CR) rates of 70‒90% have been observed, relapse due to target antigen downregulation or loss is the major cause of treatment failure. This Phase I/II study evaluates the safety and efficacy of AUTO3, a CAR T-cell therapy designed to target CD19 and CD22 simultaneously in order to reduce the likelihood of relapse due to antigen loss. Methods & Patients We constructed a novel bicistronic retroviral vector encoding both an anti-CD19 CAR and an anti-CD22 CAR. Antigen binding domains were humanized and both CARs are in "2nd generation" format (incorporating an OX40 co-stimulatory domain for the CD19 CAR and a 41BB for the CD22 CAR). The performance of the CD22 CAR was optimized by incorporating a novel pentameric spacer. The cell product was manufactured on a semi-automated and closed process using CliniMACS® Prodigy (Miltenyi Biotec). Patients (1‒24 years of age) with high risk relapse (IBFM criteria) or relapse post-allogeneic stem cell transplant (SCT), adequate performance score/organ function, and an absolute lymphocyte count ≥0.5 x 109/L are eligible. Patients with CNS 3 disease, active graft versus host disease, and clinically significant infection or serious toxicity from prior CAR T-cell are excluded. Patients receive lymphodepletion with 30 mg/m2/day fludarabine x 4 days and 500 mg/m2/day cyclophosphamide x 2 days prior to AUTO3 infusion. Three dose levels are being explored (1 x 106, 3 x 106, and 5 x 106 transduced CAR+ T cells/kg) and CAR T cells are infused as a single (for <25% blasts) or split (for >25% blasts) dose based on leukemia burden. Bridging therapy is allowed during the manufacturing period. The primary endpoint of Phase I is the frequency of dose-limiting toxicities (DLTs) and key secondary endpoints include proportion of patients achieving a morphological/minimal residual disease (MRD) negative CR, disease-free survival, overall survival, as well as biomarker endpoints including AUTO3 levels and persistence in blood and bone marrow. Results As of the data cut-off date (July 16, 2018), 9 patients have been enrolled and 8 have received AUTO3. It was possible to generate a product in all patients and the median transduction efficiency was 16% (range 9‒34%). Median age was 7.5 years (range 4‒16 years) and 5 (63%) patients had prior SCT. One patient (13%) had prior anti-CD19 CAR-T cells and blinatumomab. The disease burden at Day ‒7 ranged from 0% to 90% leukemic blasts. Eight patients had a minimum of 4 weeks' follow up and were evaluable for safety and efficacy analysis. Three patients received ≤1 × 106 CAR T cells/kg as single dose, 1 patient received 2 × 106/kg as split dose, and 4 received 3 × 106 CAR cells/kg (3 single infusions, 1 split). No AUTO3 related deaths and no DLTs were observed. The most common grade (Gr) ≥3 adverse events were neutropenia (63%), febrile neutropenia (50%), pyrexia (25%), and anemia (25%). Five patients (63%) had Gr 1 cytokine release syndrome (CRS); no Gr 2 or higher CRS was seen. Five patients (63%) experienced neurotoxicity: 4 had Gr 1 and 1 patient (13%) had Gr 3 encephalopathy that was considered likely related to prior intrathecal methotrexate. No patients required ICU admission. Six of 8 patients achieved MRD negative CR, giving an objective response rate of 75% (95% CI 34.9‒96.8%) at 1 month. In patients treated at doses <3 x 106/kg, 3 responded but subsequently relapsed. Importantly, no loss of CD19 or CD22 was noted in patients that relapsed. All 4 patients treated at the higher dose of 3 × 106 CAR T cells/kg had an MRD negative CR with ongoing remission and B-cell aplasia, with the longest follow up of 4 months. CAR T-cell expansion was enhanced in patients receiving 3 x 106/kg (median 79,282 copies/µg DNA in blood at peak) compared to those receiving lower doses (median 10,243 copies/µg DNA). Conclusion This interim data analysis demonstrates for the first time the feasibility and safety of simultaneous targeting of CD19 and CD22 with AUTO3. Promising efficacy was demonstrated at a dose level of 3 × 106 CAR T cells/kg, as 4/4 patients achieved MRD complete remission with no antigen negative escape at this early stage. The study continues to enrol and updated follow up and additional patient data at higher dose levels, as well as cellular kinetics and additional biomarker analysis, will be presented. Disclosures Wynn: Orchard SAB: Membership on an entity's Board of Directors or advisory committees; Orchard Therapeutics: Equity Ownership; Chimerix: Research Funding; Genzyme: Honoraria; Bluebird Bio: Consultancy; Orchard Therapeutics: Consultancy; Chimerix: Consultancy. Hough:University College London Hospital's NHS Foundation Trust: Employment. Vora:Amgen: Other: Advisory board; Medac: Other: Advisory board; Novartis: Other: Advisory board; Pfizer: Other: Advisory board; Jazz: Other: Advisory board. Veys:Servier: Research Funding; Pfizer: Honoraria; Novartis: Honoraria. Chiesa:Gilead: Consultancy; Bluebird Bio: Consultancy. Al-Hajj:Autolus Ltd: Employment; Autolus Ltd: Equity Ownership. Cordoba:Autolus Ltd: Employment; Autolus Ltd: Equity Ownership; Autolus Ltd: Patents & Royalties. Onuoha:Autolus Ltd: Employment, Equity Ownership, Patents & Royalties. Kotsopoulou:Autolus Ltd: Equity Ownership; Autolus Ltd: Employment. Khokhar:Autolus Ltd: Employment; Autolus Ltd: Equity Ownership. Pule:Autolus Ltd: Employment, Equity Ownership, Other: Salary contribution paid for by Autolus, Research Funding; University College London: Patents & Royalties: Patent with rights to Royalty share through UCL. Peddareddigari:Autolus Therapeutics plc: Equity Ownership; Autolus Therapeutics plc: Patents & Royalties; Autolus Therapeutics plc: Employment.

scholarly journals Feasibility, and Efficacy of Donor-Derived cd19-Targeted Car t-Cell Therapy in Refractory/Relapsed(r/r)b-Cell Acute Lymphoblastic Leukemia (b-all) Patients

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 4-6
Author(s):  
Xian Zhang ◽  
Junfang Yang ◽  
Wenqian Li ◽  
Gailing Zhang ◽  
Yunchao Su ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T ◽  
Grade 3

Backgrounds As CAR T-cell therapy is a highly personalized therapy, process of generating autologous CAR-T cells for each patient is complex and can still be problematic, particularly for heavily pre-treated patients and patients with significant leukemia burden. Here, we analyzed the feasibility and efficacy in 37 patients with refractory/relapsed (R/R) B-ALL who received CAR T-cells derived from related donors. Patients and Methods From April 2017 to May 2020, 37 R/R B-ALL patients with a median age of 19 years (3-61 years), were treated with second-generation CD19 CAR-T cells derived from donors. The data was aggregated from three clinical trials (www.clinicaltrials.gov NCT03173417; NCT02546739; and www.chictr.org.cn ChiCTR-ONC-17012829). Of the 37 patients, 28 were relapsed following allogenic hematopoietic stem cell transplant (allo-HSCT) and whose lymphocytes were collected from their transplant donors (3 HLA matched sibling and 25 haploidentical). For the remaining 9 patients without prior transplant, the lymphocytes were collected from HLA identical sibling donors (n=5) or haploidentical donors (n=4) because CAR-T cells manufacture from patient samples either failed (n=5) or blasts in peripheral blood were too high (&gt;40%) to collect quality T-cells. The median CAR-T cell dose infused was 3×105/kg (1-30×105/kg). Results For the 28 patients who relapsed after prior allo-HSCT, 27 (96.4%) achieved CR within 30 days post CAR T-cell infusion, of which 25 (89.3%) were minimal residual disease (MRD) negative. Within one month following CAR T-cell therapy, graft-versus-host disease (GVHD) occurred in 3 patients including 1 with rash and 2 with diarrhea. A total of 19 of the 28 (67.9%) patients had cytokine release syndrome (CRS), including two patients (7.1%) with Grade 3-4 CRS. Four patients had CAR T-cell related neurotoxicity including 3 with Grade 3-4 events. With a medium follow up of 103 days (1-669days), the median overall survival (OS) was 169 days (1-668 days), and the median leukemia-free survival (LFS) was 158 days (1-438 days). After CAR T-cell therapy, 15 patients bridged into a second allo-HSCT and one of 15 patients (6.7%) relapsed following transplant, and two died from infection. There were 11 patients that did not receive a second transplantation, of which three patients (27.3%) relapsed, and four parents died (one due to relapse, one from arrhythmia and two from GVHD/infection). Two patients were lost to follow-up. The remaining nine patients had no prior transplantation. At the time of T-cell collection, the median bone marrow blasts were 90% (range: 18.5%-98.5%), and the median peripheral blood blasts were 10% (range: 0-70%). CR rate within 30 days post CAR-T was 44.4% (4/9 cases). Six patients developed CRS, including four with Grade 3 CRS. Only one patient had Grade 3 neurotoxicity. No GVHD occurred following CAR T-cell therapy. Among the nine patients, five were treated with CAR T-cells derived from HLA-identical sibling donors and three of those five patients achieved CR. One patient who achieved a CR died from disseminated intravascular coagulation (DIC) on day 16. Two patients who achieved a CR bridged into allo-HSCT, including one patient who relapsed and died. One of two patients who did not response to CAR T-cell therapy died from leukemia. Four of the nine patients were treated with CAR T-cells derived from haploidentical related donors. One of the four cases achieved a CR but died from infection on day 90. The other three patients who had no response to CAR T-cell therapy died from disease progression within 3 months (7-90 days). Altogether, seven of the nine patients died with a median time of 19 days (7-505 days). Conclusions We find that manufacturing CD19+ CAR-T cells derived from donors is feasible. For patients who relapse following allo-HSCT, the transplant donor derived CAR-T cells are safe and effective with a CR rate as high as 96.4%. If a patient did not have GVHD prior to CAR T-cell therapy, the incidence of GVHD following CAR T-cell was low. Among patients without a history of transplantation, an inability to collect autologous lymphocytes signaled that the patient's condition had already reached a very advanced stage. However, CAR T-cells derived from HLA identical siblings can still be considered in our experience, no GVHD occurred in these patients. But the efficacy of CAR T-cells from haploidentical donors was very poor. Disclosures No relevant conflicts of interest to declare.

scholarly journals Automated Manufacture of Matched Donor-Derived Allogeneic CD19 CAR T-Cells for Relapsed/Refractory B-ALL Following Allogeneic Stem Cell Transplantation: Toxicity, Efficacy and the Important Role of Lymphodepletion

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 776-776
Author(s):  
Claire Roddie ◽  
Maeve A O'Reilly ◽  
Maria A V Marzolini ◽  
Leigh Wood ◽  
Juliana Dias Alves Pinto ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Board Of Directors ◽  
Research Funding ◽  
Advisory Committees ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Peak Car ◽  
Matched Donor

Introduction: 2nd generation CD19 CAR T cells show unprecedented efficacy in B-ALL, but several challenges remain: (1) scaling manufacture to meet patient need and (2) feasibility of generating products from lymphopenic patients post allogeneic stem cell transplant (allo-SCT). To overcome these issues we propose: (1) use of the CliniMACS Prodigy (Miltenyi Biotec), a semi-automated cGMP platform that simplifies CAR T cell manufacture and (2) the use of matched donor T cells to overcome the challenge posed by patient lymphopenia, albeit this may come with a heightened risk of graft versus host disease (GvHD). CARD (NCT02893189) is a Phase I study of matched donor derived CD19 CAR T cells generated on the CliniMACS Prodigy in 14 adult patients with relapsed/refractory (r/r) B ALL following allo-SCT. We additionally explore the requirement for lymphodepletion (LD) in the allogeneic CAR T cell setting and report on the incidence of GvHD with this therapy. Methods: Manufacturing: CARD utilises non-mobilised matched donor leucapheresate to manufacture 2nd generation CD19CAR T cells using a closed CliniMACS® Prodigy/ TransACTTM process. Study design: Eligible subjects are aged 16-70y with r/r B ALL following allo SCT. Study endpoints include feasibility of CD19CAR T cell manufacture from allo-SCT donors on the CliniMACS Prodigy and assessments of engraftment and safety including GvHD. To assess the requirement for LD prior to CD19CAR T cells in lymphopenic post-allo-SCT patients, the study is split into Cohort 1 (no LD) and Cohort 2 (fludarabine (30 mg/m2 x3) and cyclophosphamide (300mg/m2 x3)). To mitigate for the potential GvHD risk, cell dosing on study mirrors conventional donor lymphocyte infusion (DLI) schedules and is based on total CD3+ (not CAR T) cell numbers: Dose 1=1x106/kg CD3+ T cells; Dose 2= 3x106/kg CD3+ T cells; Dose 3= 1x107/kg CD3+ T cells. Results: As of 26 July 2019, 17 matched allo SCT donors were leukapheresed and 16 products were successfully manufactured and QP released. Patient demographics are as follows: (1) median patient age was 43y (range 19-64y); (2) 4/17 had prior blinatumomab and 5/17 prior inotuzumab ozogamicin; (3) 7/17 had myeloablative allo SCT and 10/17 reduced intensity allo SCT of which 6/17 were sibling donors and 12/17 were matched unrelated donors. No patients with haploidentical transplant were enrolled. To date, 12/16 patients have received at least 1 dose of CD19CAR T cells: 7/16 on Cohort 1 and 5/16 on Cohort 2 (2/16 are pending infusion on Cohort 2 and 2/16 died of fungal infection prior to infusion). Median follow-up for all 12 patients is 22.9 months (IQR 2.9-25.9; range 0.7 - 25.9). At the time of CAR T cell infusion, 7/12 patients were in morphological relapse with &gt;5% leukemic blasts. Despite this, CD19CAR T cells were administered safely: only 2/12 patients experienced Grade 3 CRS (UPenn criteria), both in Cohort 1, which fully resolved with Tocilizumab and corticosteroids. No patients experienced ≥Grade 3 neurotoxicity and importantly, no patients experienced clinically significant GvHD. In Cohort 1 (7 patients), median peak CAR expansion by flow was 87 CD19CAR/uL blood whereas in Cohort 2 (5 patients to date), median peak CAR expansion was 1309 CD19CAR/uL blood. This difference is likely to reflect the use of LD in Cohort 2. CAR T cell persistence by qPCR in Cohort 1 is short, with demonstrable CAR in only 2/7 treated patients at Month 2. Data for Cohort 2 is immature, but this will also be reported at the meeting in addition to potential mechanisms underlying the short persistence observed in Cohort 1. Of the 10 response evaluable patients (2/12 pending marrow assessment), 9/10 (90%) achieved flow/molecular MRD negative CR at 6 weeks. 2/9 responders experienced CD19 negative relapse (one at M3, one at M5) and 3/9 responders experienced CD19+ relapse (one at M3, one at M9, one at M12). 4/10 (40%) response evaluable patients remain on study and continue in flow/molecular MRD negative remission at a median follow up of 11.9 months (range 2.9-25.9). Conclusions: Donor-derived matched allogeneic CD19 CAR T cells are straightforward to manufacture using the CliniMACS Prodigy and deliver excellent early remission rates, with 90% MRD negative CR observed at Week 6 in the absence of severe CAR associated toxicity or GvHD. Peak CAR expansion appears to be compromised by the absence of LD and this may lead to a higher relapse rate. Updated results from Cohorts 1 and 2 will be presented. Disclosures Roddie: Novartis: Consultancy; Gilead: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau. O'Reilly:Kite Gilead: Honoraria. Farzaneh:Autolus Ltd: Equity Ownership, Research Funding. Qasim:Autolus: Equity Ownership; Orchard Therapeutics: Equity Ownership; UCLB: Other: revenue share eligibility; Servier: Research Funding; Bellicum: Research Funding; CellMedica: Research Funding. Linch:Autolus: Membership on an entity's Board of Directors or advisory committees. Pule:Autolus: Membership on an entity's Board of Directors or advisory committees. Peggs:Gilead: Consultancy, Speakers Bureau; Autolus: Membership on an entity's Board of Directors or advisory committees.

scholarly journals Human CD83 Targeted Chimeric Antigen Receptor T Cell for the Prevention of Graft Versus Host Disease and Treatment of Myeloid Leukemia

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 196-196
Author(s):  
Bishwas Shrestha ◽  
Kelly Walton ◽  
Jordan Reff ◽  
Elizabeth M. Sagatys ◽  
Nhan Tu ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Board Of Directors ◽  
Research Funding ◽  
Advisory Committees ◽  
Graft Versus Host ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Fund Research

Distinct from pharmacologic immunosuppression, we designed a programmed cytolytic effector T cell that prevents graft versus host disease (GVHD). CD83 is expressed on allo-activated conventional T cells (Tconv) and pro-inflammatory dendritic cells (DCs), which are implicated in GVHD pathogenesis. Therefore we developed a novel human CD83 targeted chimeric antigen receptor (CAR) T cell for GVHD prophylaxis. Here we demonstrate that human CD83 CAR T cells eradicate cell mediators of GVHD, significantly increase the ratio of regulatory T cells (Treg) to allo-activated Tconv, and provide lasting protection from xenogeneic GVHD. Further, we show human, acute myeloid leukemia (AML) expresses CD83 and can be targeted by CD83 CAR T cells. A 2nd generation CD83 CAR was generated with CD3ζ and 41BB costimulatory domain that was retrovirally transduced in human T cells to generate CD83 CAR T cells. The CD83 CAR construct exhibited a high degree of transduction efficiency of about 60%. The CD83 CAR T cells demonstrated robust IFN-γ and IL-2 production, killing, and proliferation when cultured with CD83+ target cells. To test whether human CD83 CAR T cells reduce alloreactivity in vitro, we investigated their suppressive function in allogeneic mixed leukocyte reactions (alloMLR). CD83 CAR T cells were added to 5-day alloMLRs consisting of autologous T cells and allogeneic monocyte-derived DCs at ratios ranging from 3:1 to 1:10. The CD83 CAR T cells potently reduced alloreactive T cell proliferation compared to mock transduced and CD19 CAR T cells. We identified that CD83 is differentially expressed on alloreactive Tconv, compared to Tregs. Moreover, the CD83 CAR T cell efficiently depletes CD83+ Tconv and proinflammatory DCs with 48 hours of engagement. To test the efficacy of human CD83 CAR T cells in vivo, we used an established xenogeneic GVHD model, where mice were inoculated with human PBMCs (25x106) and autologous CD83 CAR (1-10x106) or mock transduced T cells. The CD83 CAR T cells were well tolerated by the mice, and significantly improved survival compared to mock transduced T cells (Figure 1A). Mice treated with CD83 CAR T cells exhibited negligible GVHD target organ damage at day +21 (Figure 1B). Mice inoculated with CD83 CAR T cells demonstrated significantly fewer CD1c+, CD83+ DCs (1.7x106 v 6.2x105, P=0.002), CD4+, CD83+ T cells (4.8x103 v 5.8x102, P=0.005), and pathogenic Th1 cells (3.1x105 v 1.1x102, P=0.005) at day +21, compared to mice treated with mock transduced T cells. Moreover, the ratio of Treg to alloreactive Tconv (CD25+ non-Treg) was significantly increased among mice treated with CD83 CAR T cells (78 v 346, P=0.02), compared to mice injected with mock transduced T cells. Further, CD83 appears to be a promising candidate to target myeloid malignancies. We observed CD83 expression on malignant myeloid K562, Thp-1, U937, and MOLM-13 cells. Moreover, the CD83 CAR T cells effectively killed AML cell lines. Many AML antigens are expressed on progenitor stem cells. Thus, we evaluated for stem cell killing in human colony forming unit (CFU) assays, which demonstrated negligible on-target, off-tumor toxicity. Therefore, the human CD83 CAR T cell is an innovative cell-based approach to prevent GVHD, while providing direct anti-tumor activity against myeloid malignancies. Figure Disclosures Blazar: Kamon Pharmaceuticals, Inc: Membership on an entity's Board of Directors or advisory committees; Five Prime Therapeutics Inc: Co-Founder, Membership on an entity's Board of Directors or advisory committees; BlueRock Therapeutics: Membership on an entity's Board of Directors or advisory committees; Abbvie Inc: Research Funding; Leukemia and Lymphoma Society: Research Funding; Childrens' Cancer Research Fund: Research Funding; KidsFirst Fund: Research Funding; Tmunity: Other: Co-Founder; Alpine Immune Sciences, Inc.: Research Funding; RXi Pharmaceuticals: Research Funding; Fate Therapeutics, Inc.: Research Funding; Magenta Therapeutics and BlueRock Therapeuetics: Membership on an entity's Board of Directors or advisory committees; Regeneron Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Davila:Atara: Research Funding; Celgene: Research Funding; Precision Biosciences: Consultancy; Bellicum: Consultancy; GlaxoSmithKline: Consultancy; Adaptive: Consultancy; Anixa: Consultancy; Novartis: Research Funding.

scholarly journals B-CLL Mediated Resistance to CAR T Cell Therapy Via Insufficient Activation Is CAR-Independent

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 44-44
Author(s):  
McKensie Collins ◽  
Weimin Kong ◽  
Inyoung Jung ◽  
Stefan M Lundh ◽  
J. Joseph Melenhorst
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
Research Funding ◽  
Cytokine Production ◽  
Cell Function ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

Chronic Lymphocytic Leukemia (CLL) is a B cell malignancy that accounts for nearly 1/3rd of adult leukemia diagnoses in the Western world. Conventional chemo-immunotherapies initially control progression, but in the absence of curative options patients ultimately succumb to their disease. Chimeric Antigen Receptor (CAR) T cell therapy is potentially curative, but only 26% of CLL patients have a complete response. CLL-stimulated T cells have reduced effector functions and B-CLL cells themselves are believed to be immunosuppressive. Our work demonstrates that insufficient activation of CAR T cells by CLL cells mediates some of these effects and that the results are conserved between ROR1- and CD19-targeting CARs. Results: In this study we used an in vitro system to model the in vivo anti-tumor response in which CAR T cells serially engage with CLL cells. Multiple stimulations of CD19 or ROR1-targeting CAR T cells with primary CLL cells recapitulated many aspects of known T cell dysfunction including reduced proliferation, cytokine production, and activation. While the initial stimulation induced low level proliferation, subsequent stimulations failed to elicit additional effector functions. We further found that these functional defects were not permanent, and that CAR T cell function could be restored by switching to a stimulus with an aAPC (artificial Antigen Presenting Cell) control cell line. The aAPCs are well-characterized as potent stimulators of CAR T cell effector responses. Flow cytometry revealed that CLL-stimulated CAR T cells retained a non-activated, baseline differentiation profile, suggesting that CLL cells fail to stimulate CAR T cells rather than rendering them non-functional. One mechanism that could dampen activation is immune suppression. We assessed this at a high level by stimulating CAR T cells with CLL cells and aAPCs mixed at known ratios. However, even cultures containing 75% CLL cells stimulated proliferation and cytokine production. Extensive immune-phenotyping revealed high level expression of the IL-2 Receptor on 90% (18/20) of the B-CLL cells tested. Since cytokine sinking via IL-2 receptor expression is a well-known mechanism of regulatory T cell suppression, we hypothesized that CLL cells similarly sink IL-2, blunting T cell activation. To test this, we supplemented IL-2 into CLL/CAR T cell co-cultures and showed that this rescued proliferation but only partially restored cytokine production. In contrast to our hypothesis, analysis of cytokine production by flow cytometry showed that CLL-stimulated CAR T cells did not produce IL-2 following a 6- or 12-hour stimulus, but TNFα was expressed after 12-hours. Similarly, CAR T cell degranulation, a prerequisite for target cell lysis was triggered after CLL recognition. These data again suggested that CLL cells insufficiently stimulate CAR T cell cytokine production, but also showed that cytolytic activity against CLL cells is intact. We further proposed that CLL cells express insufficient levels of co-stimulatory and adhesion molecules to activate CAR T cells. Flow cytometry showed that most CLL cells expressed co-stimulatory and adhesion molecules at low levels; we hypothesized that up-regulating these molecules would enhance CAR T cell targeting of CLL cells. CLL cells were activated with CD40L and IL-4, which increased expression of CD54, CD58, CD80, and CD86. Stimulating CAR T cells with activated CLL cells enhanced CAR T cell proliferation and induced cell conjugate formation, indicating cell activation. Therefore, improving CLL stimulatory capacity can rescue T cell dysfunctions. To assess whether IL-2 addition and CD40 ligation were synergistic, we combined the two assays; however, we saw no additional improvement over IL-2 addition alone, suggesting that the two interventions may act upon the same pathway. Importantly, we also showed that rescue of CAR T cell function via IL-2 addition or CD40 ligation was not CAR-specific, as we observed the functional defects and subsequent rescue with both a ROR1-targeting CAR and the gold standard CD19-targeting CAR. Conclusions: Together, these data show that CAR T cell "defects" in CLL are actually insufficient activation, and improving the stimulatory capacity of CLL cells may enable better clinical responses. Further, this effect is not CAR-specific and these results may therefore be broadly applicable to multiple therapies for this disease. Disclosures Melenhorst: IASO Biotherapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Kite Pharma: Research Funding; Novartis: Other: Speaker, Research Funding; Johnson & Johnson: Consultancy, Other: Speaker; Simcere of America: Consultancy; Poseida Therapeutics: Consultancy.

scholarly journals Allogeneic Hematopoietic Cell Transplantation Is Critical to Maintain Remissions after CD19-CAR T-Cell Therapy for Pediatric ALL: A Single Center Experience

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 39-40
Author(s):  
Aimee C Talleur ◽  
Renee M. Madden ◽  
Amr Qudeimat ◽  
Ewelina Mamcarz ◽  
Akshay Sharma ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
T Cell Therapy ◽  
Allogeneic Hct ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T

CD19-CAR T-cell therapy has shown remarkable efficacy in pediatric patients with relapsed and/or refractory B-cell acute lymphoblastic leukemia (r/r ALL). Despite high short-term remission rates, many responses are not durable and the best management of patients who achieve a complete response (CR) post-CAR T-cell therapy remains controversial. In particular, it is unclear if these patients should be observed or proceed to consolidative allogeneic hematopoietic cell transplantation (HCT). To address this question, we reviewed the clinical course of all patients (n=22) who received either an investigational CAR T-cell product (Phase I study: SJCAR19 [NCT03573700]; n=12) or tisagenlecleucel (n=10) at our institution. The investigational CD19-CAR T cells were generated by a standard cGMP-compliant procedure using a lentiviral vector encoding a 2nd generation CD19-CAR with a FMC63-based CD19 binding domain, CD8a stalk and transmembrane domain, and 41BB.ζ signaling domain. Patients received therapy between 8/2018 and 3/2020. All products met manufacturing release specifications. Within the entire cohort, median age at time of infusion was 12.3 years old (range: 1.8-23.5) and median pre-infusion marrow burden using flow-cytometry minimal residual disease (MRD) testing was 6.8% (range: 0.003-100%; 1 patient detectable by next-generation sequencing [NGS] only). All patients received lymphodepleting chemotherapy (fludarabine, 25mg/m2 daily x3, and cyclophosphamide, 900mg/m2 daily x1), followed by a single infusion of CAR T-cells. Phase I product dosing included 1x106 CAR+ T-cells/kg (n=6) or 3x106 CAR+ T-cells/kg (n=6). Therapy was well tolerated, with a low incidence of cytokine release syndrome (any grade: n=10; Grade 3-4: n=4) and neurotoxicity (any grade: n=8; Grade 3-4: n=3). At 4-weeks post-infusion, 15/22 (68.2%) patients achieved a CR in the marrow, of which 13 were MRDneg (MRDneg defined as no detectable leukemia by flow-cytometry, RT-PCR and/or NGS, when available). Among the 2 MRDpos patients, 1 (detectable by NGS only) relapsed 50 days after CAR T-cell infusion and 1 died secondary to invasive fungal infection 35 days after infusion. Within the MRDneg cohort, 6/13 patients proceeded to allogeneic HCT while in MRDneg/CR (time to HCT, range: 1.8-2.9 months post-CAR T-cell infusion). All 6 HCT recipients remain in remission with a median length of follow-up post-HCT of 238.5 days (range 19-441). In contrast, only 1 (14.3%) patient out of 7 MRDneg/CR patients who did not receive allogeneic HCT, remains in remission with a follow up of greater 1 year post-CAR T-cell infusion (HCT vs. no HCT: p&lt;0.01). The remaining 6 patients developed recurrent detectable leukemia within 2 to 9 months post-CAR T-cell infusion (1 patient detectable by NGS only). Notably, recurring leukemia remained CD19+ in 4 of 5 evaluable patients. All 4 patients with CD19+ relapse received a 2nd CAR T-cell infusion (one in combination with pembrolizumab) and 2 achieved MRDneg/CR. There were no significant differences in outcome between SJCAR19 study participants and patients who received tisagenlecleucel. With a median follow up of one year, the 12 month event free survival (EFS) of all 22 patients is 25% (median EFS: 3.5 months) and the 12 month overall survival (OS) 70% (median OS not yet reached). In conclusion, infusion of investigational and FDA-approved autologous CD19-CAR T cells induced high CR rates in pediatric patients with r/r ALL. However, our current experience shows that sustained remission without consolidative allogeneic HCT is not seen in most patients. Our single center experience highlights not only the need to explore maintenance therapies other than HCT for MRDneg/CR patients, but also the need to improve the in vivo persistence of currently available CD19-CAR T-cell products. Disclosures Sharma: Spotlight Therapeutics: Consultancy; Magenta Therapeutics: Other: Research Collaboration; CRISPR Therapeutics, Vertex Pharmaceuticals, Novartis: Other: Clinical Trial PI. Velasquez:St. Jude: Patents & Royalties; Rally! Foundation: Membership on an entity's Board of Directors or advisory committees. Gottschalk:Patents and patent applications in the fields of T-cell & Gene therapy for cancer: Patents & Royalties; TESSA Therapeutics: Other: research collaboration; Inmatics and Tidal: Membership on an entity's Board of Directors or advisory committees; Merck and ViraCyte: Consultancy.

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