Safety and Efficacy of Off-the-Shelf CD30.CAR-Modified Epstein-Barr Virus-Specific T Cells in Patients with CD30-Positive Lymphoma

Abstract The manufacture of individual patient-derived CAR T-cells is expensive, frequently unsuccessful, too time consuming to benefit acutely ill patients and difficult to scale for large numbers of patients. "Off-the-shelf" T cell products that are banked from healthy donors would improve accessibility, allow rapid treatment, and reduce costs. The major obstacles to the success of allogeneic T cells are graft-versus-host disease (GVHD) and graft rejection, mediated by host and recipient alloreactive T cells, respectively. To address GVHD, we are using allogeneic Epstein-Barr Virus-specific T cells (EBVSTs), which have not produced GVHD in more than 300 recipients. To prevent graft rejection we have expressed a chimeric antigen receptor for CD30 (CD30.CAR) in EBVSTs. CD30 will be upregulated by host alloreactive T cells when they encounter infused CD30.CAR EBVSTs. As a consequence, they will become targets for the CD30.CAR EBVSTs. Previous clinical studies (NCT02917083, NCT01555892, and NCT00062868) have shown that CD30.CAR T cells can destroy CD30+ lymphoma cells through their chimeric receptor, while EBVSTs can kill EBV+ lymphoma cells through their native TCR. Thus, once engrafted, banked CD30.CAR EBVSTs may kill both CD30+ and EBV+ lymphomas through their CAR and TCR respectively without causing GVHD. To assess the safety and activity of banked CD30.CAR EBVSTs, we treated patients with multiply relapsed (median of 4 prior lines of therapy; range 3-5) or refractory CD30-positive lymphomas in a Phase 1 dose escalation study using 4 × 10 7, 1 × 10 8 or 4 × 10 8 CD30.CAR EBVSTs infused after lymphodepletion with cyclophosphamide and fludarabine. Although CD30.CAR killing is not HLA restricted, selection of the CD30.CAR EBVST product for each recipient was based on the best HLA class I and class II match; this should allow endogenous EBV (when present) to boost the in vivo activity of CD30.CAR EBVSTs via their native TCRs, and augment reactivity in patients whose CD30+ malignancies are also EBV+. We have currently treated eight patients, including two at the highest dose level. The infusions have been well tolerated with no dose-limiting toxicities and in particular no cytokine release syndrome (CRS) or GVHD of any grade. We have evaluated seven of the patients. At 6-week evaluation, per Lugano criteria, two patients have had a complete response (one shown in Figure 1) and three have had a partial response (overall response rate of 71%). CD30.CAR EBVSTs were detectable for 1 week in peripheral blood, but there was no evidence of expansion. We are analyzing tumor samples for CD30.CAR EBVSTs, and will continue to assess the safety, efficacy and durability of these responses. Thus banked CD30.CAR EBVSTs can safely be given to allogeneic recipients and may cause significant tumor responses including complete remissions. These cells may be a suitable platform for other "off-the-shelf" CAR-T cell therapies. Figure 1 Figure 1. Disclosures Quach: Tessa Therapeutics: Research Funding. Ramos: Athenex: Research Funding; Novartis: Consultancy; Genentech: Consultancy; Tessa Therapeutics: Patents & Royalties, Research Funding. Grilley: Allovir: Current equity holder in publicly-traded company, Other: Leadership; QB Regulatory Consulting: Other: Ownership, project management support, Research Funding; Marker: Consultancy, Other: Regulatory and project management support. Brenner: Athenex: Membership on an entity's Board of Directors or advisory committees; Turnstone Biologics: Membership on an entity's Board of Directors or advisory committees; TScan Therapeutics: Membership on an entity's Board of Directors or advisory committees; Coya Therapeutics: Membership on an entity's Board of Directors or advisory committees; CellGenix GmbH: Membership on an entity's Board of Directors or advisory committees; Walking Fish Therapeutics: Membership on an entity's Board of Directors or advisory committees; Poseida Therapeutics: Membership on an entity's Board of Directors or advisory committees; Onkimmune: Membership on an entity's Board of Directors or advisory committees; Memgen: Membership on an entity's Board of Directors or advisory committees; Bluebird Bio: Membership on an entity's Board of Directors or advisory committees; Bellicum Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Allogene: Membership on an entity's Board of Directors or advisory committees; Abintus: Membership on an entity's Board of Directors or advisory committees; Tessa Therapeutics: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees, Other: Founder; Allovir: Current equity holder in publicly-traded company; Marker Therapeutics: Current equity holder in publicly-traded company. Heslop: Kiadis: Membership on an entity's Board of Directors or advisory committees; Allovir: Current equity holder in publicly-traded company; Gilead: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Tessa Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; Kuur Therapeutics: Research Funding; Marker Therapeutics: Current equity holder in publicly-traded company; GSK: Membership on an entity's Board of Directors or advisory committees; Fresh Wind Biotherapies: Membership on an entity's Board of Directors or advisory committees. Rouce: Tessa Therapeutics: Research Funding; Pfizer: Consultancy; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees. Lapteva: Tessa Therapeutics: Consultancy. Rooney: Tessa: Membership on an entity's Board of Directors or advisory committees, Research Funding; Marker Therapeutics: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Allovir: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees.

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A Phase 1/1b Safety Study of Prgn-3006 Ultracar-T™ in Patients with Relapsed or Refractory CD33-Positive Acute Myeloid Leukemia and Higher Risk Myelodysplastic Syndrome

Blood ◽

10.1182/blood-2020-139417 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 17-17

Author(s):

David A. Sallman ◽

Hany Elmariah ◽

Kendra L. Sweet ◽

Chetasi Talati ◽

Asmita Mishra ◽

...

Keyword(s):

T Cells ◽

Gene Transfer ◽

Board Of Directors ◽

Dose Escalation ◽

Myeloid Leukemia ◽

Research Funding ◽

Publicly Traded ◽

Advisory Committees ◽

Car T Cells ◽

Car T

Background: Therapeutic options for relapse or refractory (r/r) acute myeloid leukemia (AML) and hypomethylating agent (HMA) failure higher risk myelodysplastic syndrome (MDS) pts are limited with median overall survival of < 6 months. Consequently, novel therapies are urgently needed. CD33 is highly expressed on most myeloid leukemia stem cells with lesser expression on normal hematopoietic stem cell populations and minimal non-hematopoietic expression making CD33 a leading target in chimeric antigen receptor therapy (CAR-T) development for myeloid malignancies. However, additional barriers of CAR-T development in myeloid malignancies include long manufacturing period, expansion of CAR-T cells and potential toxicity related to on-target, off-tumor toxicity. Scientific Rationale: Current CAR-T cells utilize viral vectors for gene transfer and subsequent lengthy ex vivo expansion at centralized manufacturing facilities, which is costly and leads to cell product that is exhausted and short lived in vivo. Time is of the essence for pts with rapidly progressing disease such as r/r AML and the prolonged interval between apheresis to product infusion with current CAR-T cell therapies can be a disadvantage. Although allogeneic "off-the-shelf" products allow for rapid administration, challenges remain with rapid rejection. Precigen has developed UltraCAR-T platform to overcome these limitations by utilizing an advanced non-viral gene delivery system and a rapid, decentralized manufacturing process. UltraCAR-T cells are manufactured overnight at medical center's cGMP facility using patient's autologous T cells and administered back to patient only one day after gene transfer with no need for ex vivo expansion. PRGN-3006 UltraCAR-T cells co-express CD33 CAR, membrane bound IL-15 (mbIL15) and a kill switch. Preclinical studies have demonstrated that the expression of the mbIL15 on UltraCAR-T cells leads to maintenance of preferred stem-like memory phenotype (TSCM). Superior efficacy of UltraCAR-T cells was demonstrated in an aggressive murine xenograft model of AML where a single administration of PRGN-3006, only one day after gene transfer, showed significantly higher expansion and persistence; effectively eliminated tumor burden; and significantly improved overall survival compared to traditional CD33 CAR-T cells lacking mbIL15 expression (Blood (2019) 134(S1): 2660). Study Design: The PRGN-3006 UltraCAR-T cells are currently being evaluated in a Phase 1/1b first-in-human dose escalation/dose expansion clinical trial (NCT03927261). The study population includes adult pts (≥ 18 years) with relapsed or refractory AML and HMA failure higher risk MDS or chronic myelomonocytic leukemia (CMML) with ≥ 5% blasts. Pts who have relapsed post allogeneic stem cell transplant are allowed if > 3 months out from transplant without evidence of active graft versus host disease and off immunosuppression for 6 weeks. Key inclusion criteria include an absolute lymphocyte count ≥ 0.2k/µL, KPS > 60%, absence of other active malignancy within 1 year of study entry, daily corticosteroid dose < 10mg of prednisone daily, adequate organ function and a backup allogeneic donor should bone marrow aplasia occur. Hydroxyurea is allowed for cytoreduction with cessation 3 days prior to apheresis/infusion but can be reinitiated post-infusion. To test the hypothesis that expression of mbIL15 on PRGN-3006 cells is sufficient to promote CAR-T cell expansion and persistence, study subjects will receive PRGN-3006 infusion either without prior lymphodepletion (Cohort 1) or following lymphodepleting chemotherapy (Cohort 2 with fludarabine 30mg/m2 and cyclophosphamide 500mg/m2 days -5 to -3). Up to 5 dose levels are planned in dose escalation. All subjects will be followed for adverse events, CAR-T-related toxicities, disease response and PRGN-3006 cell expansion and persistence in blood and bone marrow compartments. In addition, the mechanisms of safety and effectiveness of PRGN-3006 cells will be evaluated with correlative assays of specific immune response pathways. Currently, the study is in the dose escalation phase and has cleared the lower dose level while demonstrating successful manufacturing of UltraCAR-T cells. Additionally, multi-center expansion of the trial is in progress. Disclosures Sallman: Celgene, Jazz Pharma: Research Funding; Agios, Bristol Myers Squibb, Celyad Oncology, Incyte, Intellia Therapeutics, Kite Pharma, Novartis, Syndax: Consultancy. Sweet:Agios: Membership on an entity's Board of Directors or advisory committees; Astellas: Honoraria; Takeda: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Stemline: Honoraria; Novartis: Membership on an entity's Board of Directors or advisory committees; Incyte: Research Funding. Talati:Astellas: Speakers Bureau; Jazz: Speakers Bureau; AbbVie: Honoraria; Pfizer: Honoraria; BMS: Honoraria. Lankford:Precigen, Inc.: Current Employment. Chan:Precigen, Inc.: Current Employment, Current equity holder in publicly-traded company. Shah:Precigen, Inc.: Current Employment; Intrexon Corporation: Current equity holder in publicly-traded company. Padron:BMS: Research Funding; Novartis: Honoraria; Kura: Research Funding; Incyte: Research Funding. Komrokji:Novartis: Honoraria; Agios: Honoraria, Speakers Bureau; Acceleron: Honoraria; AbbVie: Honoraria; JAZZ: Honoraria, Speakers Bureau; Incyte: Honoraria; Geron: Honoraria; BMS: Honoraria, Speakers Bureau. Lancet:Abbvie: Consultancy; Agios Pharmaceuticals: Consultancy, Honoraria; Astellas Pharma: Consultancy; Celgene: Consultancy, Research Funding; Daiichi Sankyo: Consultancy; ElevateBio Management: Consultancy; Jazz Pharmaceuticals: Consultancy; Pfizer: Consultancy. Sabzevari:Precigen, Inc.: Current Employment, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Compass Therapeutics: Current equity holder in publicly-traded company. Bejanyan:Kiadis Pharma: Membership on an entity's Board of Directors or advisory committees.

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A Bank of CD30.CAR-Modified, Epstein-Barr Virus-Specific T Cells That Lacks Host Reactivity and Resists Graft Rejection for Patients with CD30-Positive Lymphoma

Blood ◽

10.1182/blood-2020-141491 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 16-16

Author(s):

David H. Quach ◽

Haran R. Ganesh ◽

Sachin Thakkar ◽

Luis Becerra-Dominguez ◽

Birju Mehta ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Board Of Directors ◽

Graft Rejection ◽

Research Funding ◽

Publicly Traded ◽

Advisory Committees ◽

T Cell Therapy ◽

Barr Virus ◽

Alloreactive T Cells

While autologous T cell therapies can effectively treat B-cell leukemia and lymphoma, the personalized manufacturing process is difficult to scale, expensive and may fail. Even when autologous products are successfully manufactured, they are not immediately available to acutely ill patients. "Off-the-shelf" T cell products derived from healthy donors that can rapidly be administered, would improve accessibility and reduce the cost of T cell therapy. However, major obstacles to successful allogeneic T cell products include their potential for graft-versus-host disease (GVHD) and graft rejection, mediated by host and recipient alloreactive T cells respectively. To address GVHD, we are using Epstein-Barr Virus-specific T cells (EBVSTs) as our platform since they are virus specific rather than allospecific and have not produced GVHD in more than 300 allogeneic recipients. To prevent graft rejection we have introduced into these EBVSTs, a chimeric antigen receptor for CD30 (CD30.CAR). CD30 is upregulated during the activation of alloreactive T cells, which leads to them becoming targets. The CD30.CAR provides the additional advantage of targeting CD30-positive lymphoma and has proved safe and effective in prior clinical trials (NCT02917083) using autologous CAR-T cells. Hence, we expect off-the-shelf CD30.CAR EBVSTs to eliminate the alloreactive T cells they elicit in allogeneic hosts, and therefore persist for sufficient time to eliminate CD30-positive lymphoma, without causing GVHD. Here we show that CD30.CAR-EBVSTs resist fratricide by masking their own CD30 molecules expressed in cis, but are nonetheless protected from rejection when co-cultured with alloreactive T cells expressing CD30 in trans. Notably, CD30.CAR EBVSTs preserve the function of both their TCR and the CD30.CAR, with retention of EBV specificity and the ability to eliminate CD30-positive tumor cells. We have manufactured a bank of clinical grade CD30.CAR EBVSTs from donors with HLA types designed to provide a partial HLA match for our diverse recipients. Clinical grade CD30.CAR EBVST cultures readily expanded to sufficient numbers for a planned clinical trial and expressed the CD30.CAR on 77% to 99% of cells. All of the lines passed functional release criteria of having greater than 100 IFNɣ spot-forming units (SFU) per 105 cells in response to both latent and lytic EBV antigens, and greater than 20% specific cytolysis against a CD30-positive Hodgkin lymphoma cell line, HDLM2, at an effector to target ratio of 20:1. Although CD30.CAR killing is not HLA restricted, we will select the CD30.CAR EBVST product for each recipient, based on the best HLA class I and class II match. This will allow endogenous EBV to boost the in vivo activity of CD30.CAR EBVSTs, and will provide additional reactivity for patients with CD30-positive and EBV-positive tumors. The IND for the clinical trial (NCT04288726) has been approved and we will recruit patients with CD30-positive lymphomas including Hodgkin lymphoma, diffuse large B cell lymphoma and NK/T cell lymphoma. In summary, we present an approach to making an off-the-shelf T cell therapy that can rapidly translate to the clinic, requires no gene editing, and can serve as a platform for other CAR/TCRs to target a multiplicity of malignancies. Disclosures Quach: Tessa Therapeutics: Research Funding. Brenner:Memmgen: Membership on an entity's Board of Directors or advisory committees; Allogene: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Walking Fish: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Maker Therapeutics: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees, Other: Founder; Tessa Therapeutics: Membership on an entity's Board of Directors or advisory committees, Other: Founder; Tumstone: Membership on an entity's Board of Directors or advisory committees; Bluebird Bio: Membership on an entity's Board of Directors or advisory committees. Heslop:Tessa Therapeutics: Consultancy, Research Funding; Novartis: Consultancy; Gilead Biosciences: Consultancy; PACT Pharma: Consultancy; Kiadis: Consultancy; AlloVir: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Marker Therapeutics: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees. Ramos:Novartis: Membership on an entity's Board of Directors or advisory committees; Tessa Therapeutics: Research Funding; Kuur Therapeutics: Research Funding. Rouce:Tessa Therapeutics: Other, Research Funding; Novartis: Honoraria. Rooney:Marker Therapeutics: Current equity holder in publicly-traded company, Other: co-founder; Tessa Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Allovir: Current equity holder in publicly-traded company, Other: co-founder.

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Synergism between CAR-T Cells and a Personalized Tumor Vaccine in Hematological Malignances

Blood ◽

10.1182/blood-2021-150307 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 737-737

Author(s):

Giulia Cheloni ◽

Marzia Capelletti ◽

Daniela Torres ◽

Poorva Bindal ◽

Jessica J. Liegel ◽

...

Keyword(s):

T Cells ◽

Board Of Directors ◽

Research Funding ◽

Tumor Vaccine ◽

Publicly Traded ◽

Advisory Committees ◽

Car T Cells ◽

Car T ◽

Provision Of Services

Abstract Background: CAR-T cells are a tremendous breakthrough in the treatment of certain type of blood cancer, demonstrating impressive and durable responses. However, mechanisms of resistance and relapse have been reported. Mechanisms contributing to relapse after CAR-T therapy include the downregulation of the CAR-T target antigen and the rapid extinguishing of CAR-T cells. We have developed a personalized cancer vaccine whereby patient derived tumor cells are fused to autologous dendritic cells (DC). DC/tumor vaccine induces a broad anti-tumor immunity capable of preventing relapse but may not be effective in patients with advanced disease. Aims: We sought to overcome relapse and resistance to CAR-T therapy to improve the current response rate to CAR-T cells. To this end, we combined CAR-T cells treatment with our personalized DC/tumor vaccine. We postulated that the DC/tumor vaccine would demonstrate synergy with CAR-T cells in a setting where CAR-T cells reduce the bulky disease and the fusion vaccine prevents relapse by expanding CAR-T cells and tumor antigen specific lymphocytes. Methods: To investigate the effects of the CAR-T/fusion vaccine combination, we used the A20 murine B-cell lymphoma model. Syngeneic T cells were obtained from BALB/c mice and retrovirally transduced with a second-generation CAR construct composed of an antigen binding domain that recognizes murine CD19, the CD3ζ domain, 4-1BB as costimulatory molecule and GFP (m19BBz-GFP). GFP expression was used to assess gene-transfer efficiency and monitor the CAR-transduced T cells. The DC/tumor vaccine was obtained by PEG-mediated fusions of A20 cells and BALB/c DC. In the in vitro experiments, T cells transduced with the m19BBz-GFP CAR or non-transduced T cells were co-cultured in the presence or the absence of the DC/A20 vaccine for 3 days. Tumor killing was measured by quantifying Firefly luciferase activity (WT A20) or Renilla luciferase activity (CD19- A20). Vaccine was removed before starting the killing assay. In the in vivo experiment, B-cell lymphoma was induced in BALB/c mice by tail vein injection of A20 cells. The mice were lymphodepleted and treated with m19BBz-GFP CAR-T. The mice were then subcutaneous injected with the DC/A20 fusion vaccine or with PBS (control group). CD8+ T-cells specific for the A20 idiotype epitope were quantified by MHC Class I tetramer analysis. Results: In vitro co-culture of CAR-T cells and DC/A20 vaccine induced a memory-like CAR-T phenotype and strongly improved CAR-T persistence (measured as % of GFP+ T cells in culture). These results were confirmed in vivo where increased CAR-T percentage was observed in the bone marrow and spleen of vaccinated mice with respect to the unvaccinated control group. Moreover, in the vaccinated mice we detected CD8+ T-cells specific for the A20 idiotype epitope demonstrating the expansion of tumor-specific lymphocytes in response to the fusion vaccine. To assess whether the vaccine-induced persistence of CAR-T cells was translated in a higher tumor killing capacity, we performed an in vitro killing assay. To mimic the presence of CD19- clones in the tumor bulk, we used a mixture of WT A20 and CD19-A20 as CAR-T target cells. Enhanced killing capacity against CD19+ tumors was induced by education of the CAR-T with the vaccine. No effects on the CAR-T killing capacity against CD19- A20 were elicited by the fusion vaccine. However, when the same killing assay was performed using as effector cells a mixture of CAR-T and naïve T cells or a mixture of CAR-T and vaccine-educated T cells, we observed that the addition of vaccine-educated T cell to the CAR-T, strongly reduced both A20 WT and A20 CD19- in the cultures. Thus, vaccine-educated T cells are able to kill tumor cells independently from the presence or the absence of the CAR-T target antigen on the tumor. Conclusions: The combination of CAR-T and DC/tumor vaccine, increasing the persistence of CAR-T cells and evoking a polyclonal T cell response against tumor antigens in the non-CAR-transduced T cells, may represent a novel therapeutic strategy to overcame therapeutic resistance and improve current response rate to CAR-T therapy. Disclosures Capelletti: Caris Life Sciences: Current Employment. Stroopinsky: The Blackstone Group: Consultancy. Kufe: REATA: Consultancy, Current equity holder in publicly-traded company; Genus Oncology: Current equity holder in publicly-traded company; Hillstream BioPharma: Current equity holder in publicly-traded company; Canbas: Consultancy. Themeli: Fate Therapeutics: Patents & Royalties. Rosenblatt: Attivare Therapeutics: Consultancy; Imaging Endpoints: Consultancy; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Parexel: Consultancy; Wolters Kluwer Health: Consultancy, Patents & Royalties; Bristol-Myers Squibb: Research Funding. Sadelain: Minerva Biotechnologies: Patents & Royalties; Juno Therapeutics: Patents & Royalties; Fate Therapeutics: Other: Provision of Services (uncompensated), Patents & Royalties; Mnemo Therapeutics: Patents & Royalties; Takeda Pharmaceuticals: Other: Provision of Services, Patents & Royalties; Ceramedix: Patents & Royalties; NHLBI Gene Therapy Resource Program: Other: Provision of Services (uncompensated); St. Jude Children's Research Hospital: Other: Provision of Services; Atara Biotherapeutics: Patents & Royalties. Avigan: Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Research Funding; Kite Pharma: Consultancy, Research Funding; Juno: Membership on an entity's Board of Directors or advisory committees; Partner Tx: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Aviv MedTech Ltd: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Legend Biotech: Membership on an entity's Board of Directors or advisory committees; Chugai: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy; Parexcel: Consultancy; Takeda: Consultancy; Sanofi: Consultancy.

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Donor-Derived Adoptive T-Cell Therapy Targeting Multiple Tumor Associated Antigens to Prevent Post-Transplant Relapse in Patients with ALL

Blood ◽

10.1182/blood-2021-149332 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 471-471

Author(s):

Swati Naik ◽

Spyridoula Vasileiou ◽

Ifigeneia Tzannou ◽

Manik Kuvalekar ◽

Ayumi Watanabe ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Board Of Directors ◽

Research Funding ◽

Management Support ◽

Publicly Traded ◽

Advisory Committees ◽

Post Infusion ◽

T Cell Lines

Abstract Background: Hematopoietic stem cell transplant (HSCT) is a curative option for patients with high-risk Acute Lymphoblastic Leukemia (HR-ALL), but relapse remains a major cause of treatment failure. Strategies to enhance the graft-versus-leukemia (GVL) effect have been employed to prevent relapse, including modulating immune suppression post-HSCT to hasten immune reconstitution or with the use of donor lymphocyte infusions (DLIs). However, DLIs carry a significant risk of graft-versus-host disease (GVHD) due to the concurrent transfer of alloreactive T cells. To enhance the GVL effect while minimizing GVHD, we developed a protocol for the generation of ex vivo expanded, donor-derived T-cell lines targeting PRAME, WT1 and Survivin - tumor associated antigens that are frequently expressed in both B- and T-cell ALL. These multi-antigen-targeted T cells (multiTAAs) were adoptively transferred to pediatric and adult patients with HR-ALL who had undergone an allogeneic HSCT. Methods: Donor-derived multiTAA-specific T cells were generated by co-culturing PBMCs with autologous DCs loaded with pepmixes (15 mer peptides overlapping by 11 amino acids) spanning all 3 target antigens in the presence of a Th1-polarizing/pro-proliferative cytokine cocktail. Following 2-4 rounds of stimulation these multiTAA-specific T cells were infused to patients with ALL who had undergone an HSCT but remained at a high risk for disease relapse. Results: We have generated 15 clinical grade multiTAA-specific T cell lines comprising CD3+ T cells (mean 95.1±1.9%) with a mixture of CD4+ (mean 22.8±6.3%) and CD8+ (mean 52.5±5.3%) cells, which expressed central [CD45RO+/CD62L+: 13.5±2.8%] and effector memory markers [CD45RO+/CD62L-: 56.4±3.8%]. The expanded lines recognized the targeted antigens PRAME (range 0-370 SFC/2x10 5), WT1 (0-363 SFC/2x10 5), and Survivin (0-65 SFC/2x10 5) in an IFNg ELIspot. None of the lines reacted against non-malignant patient-derived cells (3.7±0.8% specific lysis; E: T 20:1) - a study release criterion indicating lack of alloreactivity. We have infused 11 HR-ALL patients (8 pediatric and 3 adult) with donor-derived multiTAA-specific T cells to prevent disease relapse (Table 1). Patients were administered with up to 4 infusions of cells at 3 escalating dose levels, ranging from 0.5 - 2x10 7 cells/m 2. Infusions were well tolerated with no dose-limiting toxicity, GVHD, cytokine release syndrome or other adverse events. Three patients were not evaluable per study criteria as they received >0.5mg/kg of steroids (2 patients received stress doses for septic shock and 1 for elevated liver enzymes presumed to be GVHD that was later ruled out) within 4 weeks of infusion and were replaced. Six of the 8 remaining patients infused remain in CR on long-term follow up at a median of 46.5 months post-infusion (range 9-51 months). In patients who remained in long term CR we detected an expansion of tumor-reactive T cells in their peripheral blood post-infusion against both targeted (WT1, Survivin, PRAME) and non-targeted antigens (SSX2, MAGE-A4, -A1, -A2B, -C1, MART1, AFP and NYESO1) reflecting epitope and antigen spreading, which correlated temporally (within 4 weeks) with multiTAA infusions. By contrast in the two patients who relapsed we saw no evidence of in vivo T cell amplification within the first 4 weeks after infusion. Conclusion: The preparation and infusion of donor-derived multiTAA-specific T cells to patients with B- and T-ALL post allogeneic HSCT is feasible, safe and as evidenced by in vivo tumor-directed T cell expansion and antigen spreading in patients, may contribute to disease control. This strategy may present a promising addition to current immunotherapeutic approaches for prophylaxis for leukemic relapse in HSCT recipients. Figure 1 Figure 1. Disclosures Vasileiou: Allovir: Consultancy. Tzannou: Gileas: Honoraria; Allovir: Current equity holder in publicly-traded company. Kuvalekar: Allovir: Consultancy. Watanabe: Allovir: Consultancy. Grilley: QB Regulatory Consulting: Other: Ownership, project management support, Research Funding; Marker: Consultancy, Other: Regulatory and project management support; Allovir: Current equity holder in publicly-traded company, Other: Leadership. Hill: Incyte: Membership on an entity's Board of Directors or advisory committees. Omer: Allovir: Research Funding. Gottschalk: Tessa Therapeutics: Consultancy; Immatics: Membership on an entity's Board of Directors or advisory committees; Other: Other: patents and patent applications in the field of cancer cell and gene therapy ; Tidal: Consultancy; Novartis: Consultancy; Catamaran Bio: Consultancy. Heslop: Gilead: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Kiadis: Membership on an entity's Board of Directors or advisory committees; Kuur Therapeutics: Research Funding; GSK: Membership on an entity's Board of Directors or advisory committees; Allovir: Current equity holder in publicly-traded company; Tessa Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Marker Therapeutics: Current equity holder in publicly-traded company; Fresh Wind Biotherapies: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees. Rooney: Allogene: Patents & Royalties; Bellicum: Patents & Royalties; Bluebird: Current equity holder in publicly-traded company; Allovir: Current equity holder in publicly-traded company; Alimera: Consultancy; Memgen: Consultancy; TScan Therapeutics: Consultancy; Takeda: Patents & Royalties; Marker: Current equity holder in publicly-traded company; Tessa: Consultancy, Other: Leadership, Research Funding. Vera: Allovir: Consultancy, Current equity holder in publicly-traded company, Other: Leadership, travel , accomodations, expenses, Patents & Royalties; Marker: Current Employment, Other: Travel, Accomodations, Expenses, Patents & Royalties, Research Funding. Leen: Allovir: Consultancy, Current equity holder in publicly-traded company; Marker: Current equity holder in publicly-traded company.

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Combinatorial Antigen Targeting Strategy for Acute Myeloid Leukemia

Blood ◽

10.1182/blood-2020-141540 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 22-23

Author(s):

Pinar Ataca Atilla ◽

Mary K McKenna ◽

Norihiro Watanabe ◽

Maksim Mamonkin ◽

Malcolm K. Brenner ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Board Of Directors ◽

Tumor Control ◽

Publicly Traded ◽

Advisory Committees ◽

Car T Cells ◽

Car T Cell ◽

Car T

Introduction: Efforts to safely and effectively treat acute myeloid leukemia (AML) by targeting a single leukemia associated antigen with chimeric antigen receptor T (CAR T) cells have had limited success. We determined whether combinatorial expression of chimeric antigen receptors directed to two different AML associated antigens would augment tumor eradication and prevent relapse in targets with heterogeneous expression of myeloid antigens. Methods: We generated CD123 and CD33 targeting CARs; each containing a 4-1BBz or CD28z endodomain. We analyzed the anti-tumor activity of T cells expressing each CAR alone or in co-transduction with a CLL-1 CAR with CD28z endodomain and CD8 hinge previously optimized for use in our open CAR-T cell trial for AML (NCT04219163). We analyzed CAR-T cell phenotype, expansion and transduction efficacy by flow cytometry and assessed function by in vitro and in vivo activity against AML cell lines expressing high, intermediate or low levels of the target antigens (Molm 13= CD123 high, CD33 high, CLL-1 intermediate, KG1a= CD123 low, CD33 low, CLL-1 low and HL60= CD123 low, CD33 intermediate, CLL-1 intermediate/high) For in vivo studies we used NOD.SCID IL-2Rg-/-3/GM/SF (NSGS) mice with established leukemia, determining antitumor activity by bioluminescence imaging. Results: We obtained high levels of gene transfer and expression with both single (CD33.4-1BBʓ, CD123.4-1BBʓ, CD33.CD28ʓ, CD123.CD28ʓ, CLL-1 CAR) and double transduction CD33/CD123.4-1BBʓ or CD33/CD123.CD28ʓ) although single-transductants had marginally higher total CAR expression of 70%-80% versus 60-70% after co-transduction. Constructs containing CD28 co-stimulatory domain exhibited rapid expansion with elevated peak levels compared to 41BB co-stim domain irrespective of the CAR specificity. (p<0.001) (Fig 1a). In 72h co-culture assays, we found consistently improved anti-tumor activity by CAR Ts expressing CLL-1 in combination either with CD33 or with CD123 compared to T cells expressing CLL-1 CAR alone. The benefit of dual expression was most evident when the target cell line expressed low levels of one or both target antigens (e.g. KG1a) (Fig 1b) (P<0.001). No antigen escape was detected in residual tumor. Mechanistically, dual expression was associated with higher pCD3ʓ levels compared to single CAR T cells on exposure to any given tumor (Fig 1c). Increased pCD3ʓ levels were in turn associated with augmented CAR-T degranulation (assessed by CD107a expression) in both CD4 and CD8 T cell populations and with increased TNFα and IFNɣ production (p<0.001 Fig 1d). In vivo, combinatorial targeting with CD123/CD33.CD28ʓ and CLL-1 CAR T cells improved tumor control and animal survival in lines (KG1a, MOLM13 and HL60) expressing diverse levels of the target antigens (Fig 2). Conclusion: Combinatorial targeting of T cells with CD33 or CD123.CD28z CARs and CLL-1-CAR improves CAR T cell activation associated with superior recruitment/phosphorylation of CD3ʓ, producing enhanced effector function and tumor control. The events that lead to increased pCD3ʓ after antigen engagement in the dual transduced cells may in part be due to an overall increase in CAR expression but may also reflect superior CAR recruitment after antigen engagement. We are now comparing the formation, structure, and stability of immune synapses in single and dual targeting CARs for AML. Disclosures Brenner: Walking Fish: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Bluebird Bio: Membership on an entity's Board of Directors or advisory committees; Tumstone: Membership on an entity's Board of Directors or advisory committees; Tessa Therapeutics: Membership on an entity's Board of Directors or advisory committees, Other: Founder; Maker Therapeutics: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees, Other: Founder; Memmgen: Membership on an entity's Board of Directors or advisory committees; Allogene: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees. Atilla:Bluebird Bio: Membership on an entity's Board of Directors or advisory committees; Tumstone: Membership on an entity's Board of Directors or advisory committees; Tessa Therapeutics: Membership on an entity's Board of Directors or advisory committees, Other: founder; Marker Therapeuticsa: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees, Other: Founder, Patents & Royalties; Allogene: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Walking Fish: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; Memgen: Membership on an entity's Board of Directors or advisory committees; KUUR: Membership on an entity's Board of Directors or advisory committees.

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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 ◽

10.1182/blood-2019-129640 ◽

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 >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.

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Identification of Two CAR T-Cell Populations Associated with Complete Response or Progressive Disease in Adult Lymphoma Patients Treated with Axi-Cel

Blood ◽

10.1182/blood-2019-130815 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 779-779 ◽

Cited By ~ 2

Author(s):

Zinaida Good ◽

Jay Y. Spiegel ◽

Bita Sahaf ◽

Meena B. Malipatlolla ◽

Matthew J. Frank ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Board Of Directors ◽

Research Funding ◽

Advisory Board ◽

Advisory Committees ◽

Car T Cells ◽

Scientific Advisory Board ◽

Car T ◽

Scientific Advisory

Axicabtagene ciloleucel (Axi-cel) is an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy approved for the treatment of relapsed or refractory diffuse large B-cell lymphoma (r/r DLBCL). Long-term analysis of the ZUMA-1 phase 1-2 clinical trial showed that ~40% of Axi-cel patients remained progression-free at 2 years (Locke et al., Lancet Oncology 2019). Those patients who achieved a complete response (CR) at 6 months generally remained progression-free long-term. The biological basis for achieving a durable CR in patients receiving Axi-cel remains poorly understood. Here, we sought to identify CAR T-cell intrinsic features associated with CR at 6 months in DLBCL patients receiving commercial Axi-cel at our institution. Using mass cytometry, we assessed expression of 33 surface or intracellular proteins relevant to T-cell function on blood collected before CAR T cell infusion, on day 7 (peak expansion), and on day 21 (late expansion) post-infusion. To identify cell features that distinguish patients with durable CR (n = 11) from those who developed progressive disease (PD, n = 14) by 6 months following Axi-cel infusion, we performed differential abundance analysis of multiparametric protein expression on CAR T cells. This unsupervised analysis identified populations on day 7 associated with persistent CR or PD at 6 months. Using 10-fold cross-validation, we next fitted a least absolute shrinkage and selection operator (lasso) model that identified two clusters of CD4+ CAR T cells on day 7 as potentially predictive of clinical outcome. The first cluster identified by our model was associated with CR at 6 months and had high expression of CD45RO, CD57, PD1, and T-bet transcription factor. Analysis of protein co-expression in this cluster enabled us to define a simple gating scheme based on high expression of CD57 and T-bet, which captured a population of CD4+ CAR T cells on day 7 with greater expansion in patients experiencing a durable CR (mean±s.e.m. CR: 26.13%±2.59%, PD: 10.99%±2.53%, P = 0.0014). In contrast, the second cluster was associated with PD at 6 months and had high expression of CD25, TIGIT, and Helios transcription factor with no CD57. A CD57-negative Helios-positive gate captured a population of CD4+ CAR T cells was enriched on day 7 in patients who experienced progression (CR: 9.75%±2.70%, PD: 20.93%±3.70%, P = 0.016). Co-expression of CD4, CD25, and Helios on these CAR T cells highlights their similarity to regulatory T cells, which could provide a basis for their detrimental effects. In this exploratory analysis of 25 patients treated with Axi-cel, we identified two populations of CD4+ CAR T cells on day 7 that were highly associated with clinical outcome at 6 months. Ongoing analyses are underway to fully characterize this dataset, to explore the biological activity of the populations identified, and to assess the presence of other populations that may be associated with CAR-T expansion or neurotoxicity. This work demonstrates how multidimensional correlative studies can enhance our understanding of CAR T-cell biology and uncover populations associated with clinical outcome in CAR T cell therapies. This work was supported by the Parker Institute for Cancer Immunotherapy. Figure Disclosures Muffly: Pfizer: Consultancy; Adaptive: Research Funding; KITE: Consultancy. Miklos:Celgene: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Kite-Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; AlloGene: Membership on an entity's Board of Directors or advisory committees; Precision Bioscience: Membership on an entity's Board of Directors or advisory committees; Miltenyi Biotech: Membership on an entity's Board of Directors or advisory committees; Becton Dickinson: Research Funding; Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Juno: Membership on an entity's Board of Directors or advisory committees. Mackall:Vor: Other: Scientific Advisory Board; Roche: Other: Scientific Advisory Board; Adaptimmune LLC: Other: Scientific Advisory Board; Glaxo-Smith-Kline: Other: Scientific Advisory Board; Allogene: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Apricity Health: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Unum Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Obsidian: Research Funding; Lyell: Consultancy, Equity Ownership, Other: Founder, Research Funding; Nektar: Other: Scientific Advisory Board; PACT: Other: Scientific Advisory Board; Bryologyx: Other: Scientific Advisory Board.

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

Blood ◽

10.1182/blood-2019-124031 ◽

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.

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Easix As Prediction Score before CAR-T Cells Vs Allogeneic Hematopoietic Cell Transplantation (alloHCT) for Relapsed/Refractory (r/r) Large B Cell Lymphoma (LBCL)

Blood ◽

10.1182/blood-2020-139615 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 11-12

Author(s):

Felix Korell ◽

Thomas Luft ◽

Michael Schmitt ◽

Sascha Dietrich ◽

Anita Schmitt ◽

...

Keyword(s):

T Cells ◽

Board Of Directors ◽

Research Funding ◽

B Cell Lymphoma ◽

Tumor Board ◽

Advisory Committees ◽

Educational Activities ◽

Bulky Disease ◽

Car T Cells ◽

Car T

BACKGROUND: In a previous study we have shown that CD19-directed chimeric antigen receptor (CAR)-T cells do not appear to be inferior to alloHCT when used as standard cellular immunotherapy (CI) for patients with multiply r/r LBCL (EBMT 2020). The purpose of the present follow-up analysis was to further compare the risk profile of the 2 cohorts by applying the EASIX score (lactate dehydrogenase (U/L) × creatinine (mg/dL)/thrombocytes (109 cells per L)), and to assess if EASIX could be used as outcome predictor in patients with r/r LBCL undergoing CAR-T and alloHCT, respectively. METHODS: Eligible were all patients referred to our institution with relapsed/refractory (R/R) DLBCL and a tumor board decision recommending treatment with CAR-T cells between 07/2018 and 02/2020 and those recommending allogeneic donor search between 2004 and 2019. Patients with DLBCL transformed from CLL were excluded. EASIX was evaluated retrospectively using uni- and multivariable analyses (with regards to age, gender and number of failed therapy lines) and mortality using Cox regression analyses. RESULTS: 41 patients intended for CAR-T cells and 60 patients intended for alloHCT were included. In both cohorts nearly all patients had active disease at indication. Cohorts were comparable for sex, time from diagnosis, ZUMA1 eligibility, and PS, but CAR-T patients tended to be older (median 56 vs 51 years, p=0.093), and had more often primary refractory and bulky disease (p=0.004 and p=0.04, respectively). Median EASIX score across both cohorts was 1.50 (0.27-70.5), with significantly higher scores in the CART group both at indication (EASIX-ind; median 1.79 and 1.22 for CAR-T and alloHCT, respectively, p=0.031) and at conditioning for CI (EASIX-pre, median 2.24 vs 1.26, p=0.005). Median OS from indication was 475d for the CAR-T cohort vs 285d for the alloHCT cohort (p=0.88). On multivariate analysis, EASIX-ind was significantly associated with adverse OS if alloHCT was intended (HR per 2fold increase 1.43, 95%CI 1.08-1.90, p=0.013), but not if CAR-T was intended (HR per 2fold increase 1.16, 95%CI 0.88-1.53, p=0.3). After CI, 12-month estimates for NRM, relapse incidence, PFS, and OS for CAR-T vs alloHCT were 3% vs 21% (p=0.04), 59% vs 44% (p=0.12), 39% vs 33% (p=0.97), and 68% vs 54% (p=0.32). EASIX-pre predicted overall survival (OS) in both CAR-T (HR per 2fold increase 2.11, 95%CI 1.21-3.7, p=0.009) and alloHCT (HR per 2fold increase 3.69, 95%CI 1.54-8.31, p=0.003) cohorts. In the alloHCT group, the EASIX effect was largely driven by higher NRM risk with increasing EASIX-pre, while in the CAR-T group poorer OS with increasing EASIX-pre was largely relapse-related. CONCLUSIONS: In patients undergoing CI for r/r LBCL, EASIX measured prior to conditioning can predict mortality after both CAR-T and alloHCT. If applied already at indication for CI, the predictive capacity of EASIX is weaker and no longer significant if CAR-T is intended. Further studies for validation of this data appear to be warrantable. Disclosures Schmitt: MSD: Membership on an entity's Board of Directors or advisory committees, Other: PI of clinical trials on letermovir; TolerogenixX Ltd: Other: Co-Founder and shareholder; Hexal: Other: Travel grants , Research Funding; Apogenix: Research Funding; Kite: Other: Travel grants, educational activities and conferences; Novartis: Other: educational activities and conferences, Research Funding. Dietrich:Roche: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; KITE: Membership on an entity's Board of Directors or advisory committees. Schmitt:Hexal: Other: Travel grants ; TolerogenixX LtD: Other: Co-founder, Part-time employee ; Therakos/Mallinckrodt: Research Funding; Jazz Pharmaceuticals: Other: Travel grants . Dreger:Neovii: Research Funding; Roche: Consultancy, Speakers Bureau; Riemser: Consultancy, Research Funding, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Janssen: Consultancy; Gilead: Consultancy, Speakers Bureau; AstraZeneca: Consultancy; AbbVie: Consultancy, Speakers Bureau.

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