Considerations for Optimal Administration of Chimeric Antigen Receptor (CAR) T-Cell Therapy Programs: A Multi-Stakeholder Qualitative Analysis

Abstract CAR-T therapies represent a novel advance in oncology, albeit at list prices that exceed $373,000 (and that does not capture their total cost to the healthcare system). Since initial product approval in 2017, stakeholders and observers have attempted to investigate clinical and financial impacts of CAR-T therapies, and potential approaches to optimizing access and use by eligible patients. Most existing research is from a single stakeholder perspective - patients, providers, or payers - limiting the ability to draw broader conclusions on trends and offer prospective recommendations. To address this knowledge gap, we sought to identify and describe critical success factors for optimal delivery of CAR-T therapies. We undertook a qualitative study based on interviews with multiple US-based stakeholders including clinicians, financial and operations staff, and payer-insurers. Interviewees--which included oncologists (n=6), facility financial and operational personnel (n=4), and coverage and reimbursement decision-makers from US health plans (n=3)--completed structured, live, hour-long, interviews covering clinical, administrative, and general topics on patient access to CAR-T therapies. All clinicians had experience with ≥1 FDA-approved CAR-T therapies in both registered clinical trials and clinical practice; financial and operational personnel were affiliated with the same facilities as the clinicians, and also had real-world experience with these therapies; payer representatives were directors from a large national commercial plan, regional integrated delivery network, and a Medicare administrative contractor, respectively. Consensus facility feedback (i.e., clinicians, operational personnel) was that CAR-T is effective, and that their administrative processes had been optimized through care team coordination and experience-based efficiencies; in contrast, 2 of 3 payer interviewees expressed that, while CAR-T therapies have shown efficacy, their real-world benefits and applicability are less well-defined. Facility interviewees noted that: (1) reimbursement from commercial insurers is higher than from Medicare, with the latter associated with per-patient net-neutral or negative margins; (2) when possible, differential reimbursement between inpatient and outpatient settings may drive patient management towards outpatient care; and (3) negative-margin cases are currently deemed acceptable due to nonclinical factors (i.e., competitive pressure within a geographic region, anticipated branding/marketing value) and relatively small treated populations. From payer interviewees, CAR-T cost and perceived cost-to-value have made health plans more receptive to considering outcomes-based contracting, capitated provider payments, or other mitigation methods. Left unoptimized, these factors may adversely impact patient access to, and long-term provider attractiveness of, CAR-T therapies. All interviewees agreed that as the CAR-T marketplace grows, a strong preference exists for manufacturers to develop and communicate for their therapies durable outcomes data, clear and comprehensive reimbursement information, and competitive pricing. With the potential for many approved products in a single indication, and/or a single approval for indications with relatively large eligible patient populations, interviewees also conveyed interest in compelling health economic data. Facility interviewees also acknowledged that if it remains an overall net-negative margin service, new providers will be less able to start CAR-T programs and smaller programs may encounter sustainability issues, collectively jeopardizing patient access to these life-changing therapies. Overall, findings from this study suggest that during the continued maturation of the landscape, stakeholders will need to be proactive to ensure that CAR T-cell therapies can be maintained amidst financial and operational pressures. Several CAR-T therapy options for multiple myeloma are on the immediate horizon, likely increasing demand among eligible patients. Accordingly, the need to link real-world evidence of the clinical value and institutional investment burden of these therapies to reimbursement is imperative, both to insulate payers and enable clinicians to provide innovative therapies. Figure 1 Figure 1. Disclosures Faber: Amgen: Honoraria; Adaptive: Honoraria; Cardinal Health: Honoraria; Celgene: Honoraria; Astra Zeneca: Honoraria; GlaxoSmith Kline: Honoraria; Janssen: Honoraria; Juno: Honoraria; Karyopharm: Honoraria; Kite: Honoraria; Takeda: Honoraria; Sanofi Genzyme: Honoraria. Hunter: BMS: Consultancy, Honoraria; Kite: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy, Honoraria. Deol: Kite, a Gilead Company: Consultancy. Crivera: Johnson & Johnson: Current Employment, Current equity holder in publicly-traded company. Riccobono: Legend Biotech: Current Employment, Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company. Garrett: Legend Biotech USA: Current Employment. Jackson: Memorial Sloan Kettering Cancer Center: Consultancy; Janssen: Current Employment. Fowler: Amgen: Ended employment in the past 24 months; Janssen: Current Employment. Berger: Janssen Scientific Affairs: Consultancy, Research Funding. Lorden: Janssen Scientific Affairs: Consultancy, Research Funding. Stewart: Janssen Scientific Affairs: Consultancy, Research Funding.

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Targeting the Membrane-Proximal C2-Set Domain of CD33 for Improved CD33-Directed CAR T Cell Therapy

Blood ◽

10.1182/blood-2021-149642 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 2776-2776

Author(s):

Salvatore Fiorenza ◽

George S. Laszlo ◽

Tinh-Doan Phi ◽

Margaret C. Lunn ◽

Delaney R. Kirchmeier ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Research Funding ◽

Set Domain ◽

Car T Cells ◽

Car T Cell ◽

Car T ◽

Privately Held

Abstract Background: There is increasing interest in targeting CD33 in malignant and non-malignant disorders, but available drugs are ineffective in many patients. As one limitation, therapeutic CD33 antibodies typically recognize the membrane-distal V-set domain. Likewise, currently tested CD33-directed chimeric antigen receptor (CAR) T cells likewise target the V-set domain and have thus far shown limited clinical activity. We have recently demonstrated that binding closer to the cell membrane enhances the effector functions of CD33 antibodies. We therefore raised antibodies against the membrane-proximal C2-set domain of CD33 and identified antibodies that bound CD33 regardless of the presence/absence of the V-set domain ("CD33 PAN antibodies"). Here, we tested their properties as targeting moiety in CD33 PAN CAR T cell constructs, using a clinically validated lentiviral backbone. Methods: To generate CAR T cells, negatively selected CD8 + T cells were transduced with an epHIV7 lentivirus encoding the scFv from a CD33 PAN antibody (clone 1H7 or 9G2) linked to either a short (IgG 4 hinge only), intermediate (hinge plus IgG 4 CH3 domain), or long (hinge plus IgG 4 CH3 domain plus IgG 4 CH2 domain) spacer, the CD28-transmembrane domain, CD3zeta and 4-1BB intracellular signaling domains, and non-functional truncated CD19 (tCD19) as transduction marker. Similar constructs using scFvs from 2 different V-set domain-targeting CD33 antibodies, including hP67.6 (My96; used in gemtuzumab ozogamicin), were generated for comparison. CAR-T cells were sorted, expanded in IL-7 and IL-15, and used in vitro or in vivo against human AML cell lines endogenously expressing CD33 and cell lines engineered to lack CD33 (via CRISPR/Cas9) with/or without forced expression of different CD33 variants. Results: CD33 V-set-directed CAR T cells exerted significantly more cytolytic activity against AML cells expressing an artificial CD33 variant lacking the C2-set domain (CD33 ΔE3-4) than cells expressing full-length CD33 at similar or higher levels, consistent with the notion that CD33 CAR T cell efficacy is enhanced when targeting an epitope that is located closer to the cell membrane. CD33 PAN CAR T cells were highly potent against human AML cells in a strictly CD33-dependent fashion, with constructs containing the short and intermediate-length spacer demonstrating robust cytokine secretion, cell proliferation, and in vitro cytolytic activity, as determined by 51Cr release cytotoxicity assays. When compared to optimized CD33 V-set CAR T cells, optimized CD33 PAN CAR T cells were significantly more potent in cytotoxicity, proliferation, and cytokine production without appreciably increased acquisition of exhaustion markers. In vivo, CD33 PAN CAR T cells extended survival in immunodeficient NOD.SCID. IL2rg -/- (NSG) mice bearing significant leukemic burdens from various cell line-derived xenografts (HL-60, KG1α and MOLM14) with efficient tumor clearance demonstrated in a dose-dependent fashion. Conclusion: Targeting the membrane proximal domain of CD33 enhances the anti-leukemic potency of CAR T cells. Our data provide the rationale for the further development of CD33 PAN CAR T cells toward clinical testing. Disclosures Fiorenza: Link Immunotherapeutics: Consultancy; Bristol Myers Squibb: Research Funding. Godwin: Pfizer: Research Funding; Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Turtle: Allogene: Consultancy; Amgen: Consultancy; Arsenal Bio: Consultancy; Asher bio: Consultancy; Astrazeneca: Consultancy, Research Funding; Caribou Biosciences: Consultancy, Current holder of individual stocks in a privately-held company; Century Therapeutics: Consultancy, Other; Eureka therapeutics: Current holder of individual stocks in a privately-held company, Other; Juno therapeutics/BMS: Patents & Royalties, Research Funding; Myeloid Therapeutics: Current holder of individual stocks in a privately-held company, Other; Nektar therapeutics: Consultancy, Research Funding; PACT Pharma: Consultancy; Precision Biosciences: Current holder of individual stocks in a privately-held company, Other; T-CURX: Other; TCR2 Therapeutics: Research Funding. Walter: Kite: Consultancy; Janssen: Consultancy; Genentech: Consultancy; BMS: Consultancy; Astellas: Consultancy; Agios: Consultancy; Amphivena: Consultancy, Other: ownership interests; Selvita: Research Funding; Pfizer: Consultancy, Research Funding; Jazz: Research Funding; Macrogenics: Consultancy, Research Funding; Immunogen: Research Funding; Celgene: Consultancy, Research Funding; Aptevo: Consultancy, Research Funding; Amgen: Research Funding.

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A Phase II Trial of Anakinra for the Prevention of CAR-T Cell Mediated Neurotoxicity

Blood ◽

10.1182/blood-2021-146927 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 2814-2814

Author(s):

Matthew J. Frigault ◽

Kathleen M.E. Gallagher ◽

Marc Wehrli ◽

Betsy Valles ◽

Keagan Casey ◽

...

Keyword(s):

T Cell ◽

Stock Options ◽

Research Funding ◽

Leadership Role ◽

Publicly Traded ◽

Car T Cell ◽

Car T ◽

Post Infusion ◽

Grade 3 ◽

Privately Held

Abstract Introduction: Chimeric antigen receptor (CAR)-T cell therapy is limited in most cases to inpatient use due to risk of severe treatment-related toxicities. The two primary toxicities observed with CAR-T therapy, cytokine release syndrome (CRS) and neurotoxicity, are associated with increased circulating inflammatory cytokines such as IL-6 and IL-1. Targeting IL-6 with tocilizumab is effective for treating CRS but not neurotoxicity. Anakinra is an FDA-approved recombinant IL-1 receptor antagonist that competitively inhibits IL-1 receptor signaling and therefore blocks downstream production of inflammatory cytokines including IL-6. Leveraging support from Kite Pharma, we opened an investigator-initiated clinical trial (NCT04150913) with the hypothesis that anakinra could be administered prophylactically to prevent severe CRS and neurologic events (NE) in patients receiving axicabtagene ciloleucel (axi-cel). Here we report preliminary outcomes of this study. Study Design and Methods: This is a phase II single center, open-label study for patients ≥18 years old with relapsed or refractory large cell lymphoma. Patients must have progressed after ≥2 lines of systemic therapy but could not have CNS disease or have been previously treated with CAR-T therapy. Following leukapheresis and manufacturing, patients received 3 days of lymphodepleting chemotherapy (LDC, cyclophosphamide 500mg/m 2 and fludarabine 30 mg/m 2) and 200 mg of subcutaneously administered anakinra starting 4 hours prior to axi-cel infusion and daily thereafter for a total of 7 days. CRS and NE were graded based on the Lee 2013 criteria and the CTCAE 4.03 criteria, respectively, to enable direct comparison to the pivotal Zuma-1 cohorts. The primary endpoint is the rate and severity of NE within the first 30 days of infusion; secondary endpoints include the incidence and severity of CRS and disease response. CAR-T cell expansion, serum cytokines, and circulating biomarkers of toxicity were measured at baseline, day 3, 7, 14, 21, and 28 post CAR-T cell infusion. Results: Interim analysis of the first 6 patients demonstrated a median age of 68 (range 59-72). Patients included a diverse group of histologies including double-hit lymphoma (n=2), transformed indolent NHL (n=3), and DLBCL NOS (n=1). Two patients were considered primary refractory at time of enrollment. Pre-LDC baseline characteristics included a median SPD of 2819 mm 2 (range 1063-5802), median LDH of 415 (range 147-497) which were comparable to the pivotal ZUMA-1 cohorts. Baseline ferritin, CRP, SAA and IL-15 were similar to the pivotal ZUMA-1 cohorts. While low-grade CRS was observed in 5/6 patients, no patients experienced severe CRS and median onset occurred on day +8 (range 1-8). Four patients did not experience any NE, while two patients experienced grade 3 NE on days +6 till +9 (somnolence) and +12 (global aphasia only, for one day) respectively. With a median follow-up of 4 months, the day +28 overall response rate was 100% (4 CRs, 2 PRs), with 4/6 patients having an ongoing complete response at last disease assessment. One patient was re-infused at progression and remains in a CR 3 months from re-infusion. Responses were seen despite varying CAR-T peak level with most patients demonstrating expansion in the lower quartile of the historic ZUMA-1 cohort. Median post-infusion peak of CRP, ferritin, IL-2, GM-CSF, IFNγ, IL-10, IL-6 and SAA were lower than that observed in the pivotal ZUMA-1 cohorts. All patients remain alive at time of data analysis. Conclusions: With a limited number of patients analyzed thus far, anakinra appears to provide benefit to the toxicity profile of axi-cel, presenting reduced and/or delayed CRS and NE and a decrease in post-infusion inflammatory analytes, when compared to ZUMA-1 pivotal cohorts. No severe CRS was observed in this initial analysis and 2/6 patients experienced grade 3 NE (somnolence and global aphasia) after day 6. Despite CAR-T expansion in the lower quartile of that of ZUMA-1, we observed a 100% ORR with 4 patients remaining in CR at a median follow-up of 4 months. Additional subjects will be assessed to investigate the role of prophylactic anakinra in the management of CRS and NE, which has potential for making axi-cel treatment an outpatient therapy. Disclosures Frigault: BMS: Consultancy; Editas: Consultancy; Iovance: Consultancy; Arcellx: Consultancy; Takeda: Consultancy; Kite: Consultancy, Research Funding; Novartis: Consultancy, Research Funding. Wehrli: CSL Behring: Patents & Royalties; Nestle: Current equity holder in publicly-traded company; Novartis: Current equity holder in publicly-traded company. Chou: Kite Pharma: Current Employment. Shen: Atara: Current Employment, Current equity holder in publicly-traded company, Other: Leadership role, Patents & Royalties; Gilead Sciences: Current equity holder in publicly-traded company; Kite, a Gilead Company: Current Employment, Other: Leadership role, Patents & Royalties. Filosto: Kite, a Gilead Company: Current Employment; Gilead Sciences: Other: stock or other ownership ; Tusk Therapeutics: Patents & Royalties: or other intellecular property. Bot: Kite, a Gilead Company: Current Employment; Gilead Sciences: Consultancy, Current equity holder in publicly-traded company, Other: Travel support. Maus: Agenus: Consultancy; Arcellx: Consultancy; Astellas: Consultancy; AstraZeneca: Consultancy; Atara: Consultancy; Bayer: Consultancy; BMS: Consultancy; Cabaletta Bio (SAB): Consultancy; CRISPR therapeutics: Consultancy; In8bio (SAB): Consultancy; Intellia: Consultancy; GSK: Consultancy; Kite Pharma: Consultancy, Research Funding; Micromedicine: Consultancy, Current holder of stock options in a privately-held company; Novartis: Consultancy; Tmunity: Consultancy; Torque: Consultancy, Current holder of stock options in a privately-held company; WindMIL: Consultancy; Adaptimmune: Consultancy; tcr2: Consultancy, Divested equity in a private or publicly-traded company in the past 24 months; century: Current equity holder in publicly-traded company; ichnos biosciences: Consultancy, Current holder of stock options in a privately-held company.

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The Utility of Granulocyte Colony Stimulating Factor in Patients Receiving Chimeric Antigen Receptor T-Cell Therapy with Axicabtagene Ciloleucel

Blood ◽

10.1182/blood-2020-142150 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 23-25

Author(s):

Jason N Barreto ◽

Corina J Doleski ◽

Justin R Hayne ◽

Matthew A Hathcock ◽

Tuan A Truong ◽

...

Keyword(s):

T Cell ◽

Research Funding ◽

Severe Neutropenia ◽

Granulocyte Colony Stimulating Factor ◽

T Cell Therapy ◽

Car T Cell ◽

Car T ◽

Baseline Characteristics ◽

Stimulating Factor ◽

Neutropenic Episode

Background: Infection during the period of neutropenia following chemotherapy represents a major cause of morbidity and mortality in patients with malignancy.(Freifeld, et al, 2011, Baden LR, et al, 2012) Several guidelines recommend granulocyte colony stimulating factor (GCSF) to reduce the duration and severity of chemotherapy-induced neutropenia and abate infection risk.(Lyman, et al 2018, Aapro, et al, 2011, Smith, et al, 2015). Optimal GCSF administration following chimeric antigen receptor (CAR) T-cell therapy remains undefined and requires characterization. Methods: The Mayo Institutional Review Board approved this retrospective, single-center study. Electronic medical records for patients prescribed axicabtagene ciloleucel were reviewed until disease relapse, death, or a maximum of 60 days after infusion. Baseline characteristics and laboratory values were abstracted prior to lymphodepleting chemotherapy. GCSF support was originally prescribed when the absolute neutrophil count (ANC) declined below 500 cells/mm3 and discontinued when the ANC exceeded 1000 cells/mm3 (neutropenia) for 2 consecutive days. A practice change was made where GCSF was recommended only in those with febrile neutropenia and an increased concern for infection. The primary endpoint was the difference in the total days of neutropenia for patients receiving and not receiving GCSF. Secondary outcomes compared total days of severe neutropenia, number of neutropenia episodes, infection rates by GCSF use, and outcomes by protocol change. Neutropenia and severe neutropenia were defined as an ANC below 500 cells/mm3 and 100 cells/mm3, respectively. Updated data with more patients will be presented at the conference. Results: The 60 included patients had a median age of 59 (IQR: 44, 63) years, 38 (63%) were male and 53 (88%) were Caucasian. Significantly fewer patients were prescribed GCSF according to infection-related concerns compared to ANC-based indication, 18% vs. 94%, p<0.001. Because only 3 subjects received GCSF based on infection-related concerns, results based on GCSF use versus no use is shown here. GCSF was prescribed to 35 (58%) patients for a median of 8 (IQR: 6, 12) doses with a median cumulative dosage of 3840 mcg (IQR 2100-5400) and median time to first dose of 3 days (IQR: 1, 4) post CAR T-cell infusion. Table 1 displays additional baseline characteristics and laboratory parameters according to GCSF support utilization. GCSF prescribed: Table 2 displays outcomes by GCSF use. Total days of neutropenia were similar between groups (13 vs. 16, p=0.52) with a trend towards significantly fewer days of severe neutropenia when prescribed GCSF (6 vs. 9, p=0.129). Patients prescribed GCSF were more likely to experience multiple episodes of neutropenia (83% vs. 43% p=0.002) with a significantly greater median number of episodes (3 vs. 1, p=0.002) when compared to those not prescribed GCSF. GCSF use significantly decreased the median days of the first neutropenia episode (6 vs. 12, p=0.001). There was a trend for decreased median days of severe neutropenia in the first episode with GCSF (5.0 vs. 8.0, p=0.236). Figure 1 displays a trend towards a lower overall risk of infection (HR 0.55, 95%CI: 0.16-1.87, p=0.34) and lower risk of bacterial infection (HR: 0.49, 95% CI: 0.18-1.31, p=0.15); however, these were not statistically significant. Conclusion: Patients prescribed GCSF according to ANC-based indication were significantly more likely to experience multiple neutropenia episodes; however, duration of first neutropenic episode and days of severe neutropenia during the first neutropenic episode were significantly reduced. Interestingly, the total days of neutropenia and severe neutropenia were similar between groups. It is possible that using the parameter of ANC more than 1000 cells/mm3 for 2 consecutive days is not the optimal criteria for stopping GCSF. Risk of overall and bacterial infection was lower with ANC-based initiation of GCSF, although non-significant likely due to small sample size. The potential benefit for using CSF and the optimal timing after CAR T-cell infusion requires further, rigorous, prospective investigation. Disclosures Ansell: ADC Therapeutics: Research Funding; Trillium: Research Funding; Affimed: Research Funding; Regeneron: Research Funding; AI Therapeutics: Research Funding; Takeda: Research Funding; Seattle Genetics: Research Funding; Bristol Myers Squibb: Research Funding. Bennani:Purdue Pharma: Other: Advisory Board; Kite/Gilead: Research Funding; Affimed: Research Funding; Verastem: Other: Advisory Board. Lin:Kite, a Gilead Company: Consultancy, Research Funding; Vineti: Consultancy; Sorrento: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gamida Cells: Consultancy; Takeda: Research Funding; Merck: Research Funding; Legend BioTech: Consultancy; Juno: Consultancy; Bluebird Bio: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy; Janssen: Consultancy, Research Funding.

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REAL-WORLD RESULTS ON CD19 CAR T-CELL FOR 60 FRENCH PATIENTS WITH RELAPSED/REFRACTORY DIFFUSE LARGE B-CELL LYMPHOMA INCLUDED IN A TEMPORARY AUTHORIZATION FOR USE PROGRAM

Hematological Oncology ◽

10.1002/hon.110_2630 ◽

2019 ◽

Vol 37 ◽

pp. 301-301 ◽

Cited By ~ 6

Author(s):

C. Thieblemont ◽

S. Le Gouill ◽

R. Di Blasi ◽

G. Cartron ◽

F. Morschhauser ◽

...

Keyword(s):

T Cell ◽

B Cell ◽

Real World ◽

Cell Lymphoma ◽

B Cell Lymphoma ◽

Car T Cell ◽

Large B Cell Lymphoma ◽

Car T ◽

Large B Cell

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

Blood ◽

10.1182/blood-2020-137638 ◽

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.

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Bleeding and Thrombosis Are Associated with Endothelial Dysfunction in CAR-T Cell Therapy and Are Increased in Patients Experiencing Neurologic Toxicity

Blood ◽

10.1182/blood-2020-142218 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 32-33

Author(s):

Andrew Johnsrud ◽

Juliana Craig ◽

John H. Baird ◽

Jay Y. Spiegel ◽

Lori S. Muffly ◽

...

Keyword(s):

T Cell ◽

Research Funding ◽

Bleeding Events ◽

Private Company ◽

T Cell Therapy ◽

Car T Cell ◽

Car T ◽

Thrombotic Complications ◽

D Dimer ◽

Support Research

Background Treatment with chimeric antigen receptor (CAR) T cell therapies have shown dramatic, often durable responses for relapsed/refractory B-cell malignancies. However, it can be associated with significant side effects such as cytokine release syndrome (CRS), immune effector-cell associated neurotoxicity syndrome (ICANS) and life-threatening consumptive coagulopathies. The underlying pathobiology of such hemostatic defects and their distinct clinical sequelae remains obscure. This retrospective study aims at quantifying CAR T therapy associated bleeding and thrombotic complications and their association with CRS, ICANS, and laboratory derangements. Methods 130 adult patients with DLBCL or B-ALL treated between 2017-2020 with CD19 CAR-T therapy axicabtagene ciloleucel (N=90) or a bispecific CD 19/22 CAR construct utilizing 4-1BB costimulatory domains (N=40) were analyzed to determine dynamics of coagulation parameters and platelet counts as well as incidences of bleeding or thrombosis in the first three months after CAR T infusion. Events were included if graded ≥ 2 or if intervention was required. Platelet counts and coagulation parameters were collected prior to lymphodepletion (pre-LD), day 0, 3, 7, 14, 21, 28, 60 and 90. Results 12 (9.2%) and 8 (6.2%) patients developed bleeding and thrombotic complications in the first three months after CAR-T infusion, respectively. Events are characterized in Figure 1. All bleeding events occurred between days 0-30 (median 17.5, range 8-30), while thrombotic events occurred between days 2-91 (median day 29, range, 2-91). Two (1.5%) patients experienced both bleeding and thrombosis. Bleeding events coincided with the onset of thrombocytopenia and hypofibrinogenemia, and patients who bled had lower platelet (median 22.5 vs. 47 K/uL; p=0.03) and fibrinogen (median 151 vs. 351 ug/mL; p=0.007) nadirs in the first 30 days compared to those without bleeding. Temporally, the lowest median platelet nadir occurred at day 7 in patients with bleeding events vs. day 21 in patients without bleeding, while timing of fibrinogen nadirs were at day 21 in both. Patients with bleeding episodes were more likely to be older (median age: 70 vs. 60 yrs, p=0.03), have thrombocytopenia prior to lymphodepletion therapy (median 117.5 vs. 174.5 K/uL, p=0.01), and have elevated LDH (lymphoma subgroup; p=0.07). Other lab derangements in the first 30 days seen more frequently in patients with bleeding included prolonged thrombin time (TT) (21% vs. 6%; p=0.02), PT (16% vs. 5%; p=0.06), and elevated d-dimer (16% vs. 3%; p=0.01) indicative of a consumptive process. Thrombotic events were not significantly associated with elevated or peak d-dimer values (median 4.97 vs. 2.37 ug/mL, p=0.20). Interestingly, occurrence or severity of CRS was not associated with bleeding or thrombotic events, nor was it associated with marked derangements in coagulation abnormalities. However, higher grade ICANS (grade > 3) was associated with bleeding (42% vs. 15%; p=0.038), thrombosis (50% vs. 16%; p=0.03), and evidence of endothelial activation including PT prolongation (78% vs. 35%; p<0.001), hypofibrinogenemia (57% vs. 20%; p=0.001), and trend towards elevated d-dimer (70% vs. 46%; p=0.06). 13 (10%) patients received anticoagulation for prophylaxis or therapeutic indications that predated CAR T infusion. Four started anticoagulation secondarily for thrombotic events after CAR-T infusion, and one received tissue plasminogen activator (tPA) for an acute stroke. In this group, no patients developed bleeding complications from anticoagulation. Conclusion Both bleeding (9.2%), and thrombotic (6.2%) events are observed after CAR T cell therapy, with bleeding limited to the first month in our cohort. Notably, ICANS was uniquely associated with PT prolongation, hypofibrinogenemia, and increased fibrin degradation, in addition to both bleeding and thrombosis. These results suggest that a systemic coagulopathy coincides with high grade ICANS and whether these neurologic events truly represent sequelae of widespread vascular dysfunction warrants further investigation. Anticoagulation was safe in the patients whom it was indicated. Risk factors for bleeding and thrombotic complications should be studied prospectively to develop risk-assessment models and clinical guidelines for management of bleeding and thrombosis (including prophylaxis) during CAR T therapy. Disclosures Muffly: Adaptive: Research Funding; Servier: Research Funding; Amgen: Consultancy. Negrin:BioEclipse Therapeutics: Current equity holder in private company; Magenta Therapeutics: Consultancy, Current equity holder in publicly-traded company; KUUR Therapeutics: Consultancy; Biosource: Current equity holder in private company; Amgen: Consultancy; UpToDate: Honoraria. Shizuru:Jasper Therapeutics, Inc: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees. Meyer:Orca Bio: Research Funding. Shiraz:Kite, a Gilead Company: Research Funding; ORCA BioSystems: Research Funding. Rezvani:Pharmacyclics: Research Funding. Mackall:Apricity Health: Consultancy, Current equity holder in private company; NeoImmune Tech: Consultancy; Nektar Therapeutics: Consultancy; Allogene: Current equity holder in publicly-traded company; BMS: Consultancy; Lyell Immunopharma: Consultancy, Current equity holder in private company. Miklos:Adaptive Biotech: Consultancy, Other: Travel support, Research Funding; Kite-Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Research Funding; Juno-Celgene-Bristol-Myers Squibb: Consultancy, Other: Travel support, Research Funding; Allogene Therapeutics Inc.: Research Funding; Novartis: Consultancy, Other: Travel support, Research Funding; Pharmacyclics: Consultancy, Other: Travel support, Patents & Royalties, Research Funding; Janssen: Consultancy, Other: Travel support; Miltenyi Biotec: Research Funding. Sidana:Janssen: Consultancy.

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Costs of Postinfusion Monitoring By Site of Care for Patients with Relapsed/Refractory (R/R) Large B-Cell Lymphoma (LBCL) Who Received Third-Line or Later Treatment with Lisocabtagene Maraleucel (liso-cel) in the Transcend NHL 001 and Outreach Trials

Blood ◽

10.1182/blood-2020-141415 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 16-17

Author(s):

M. Lia Palomba ◽

Monika P. Jun ◽

Jacob Garcia ◽

James Lymp ◽

November McGarvey ◽

...

Keyword(s):

T Cell ◽

Cell Therapy ◽

Research Funding ◽

Cost Ratio ◽

Publicly Traded ◽

T Cell Therapy ◽

Car T Cell ◽

Car T Cell Therapy ◽

Car T ◽

Third Line

Background: Chimeric antigen receptor (CAR) T cell therapy is generally limited to inpatient settings; yet, exploration of outpatient infusion and monitoring is ongoing. Information on health care resource utilization (HCRU) and costs associated with CAR T cell therapy administration is limited and may differ by postinfusion monitoring site. Liso-cel is an investigational, CD19-directed, defined composition, 4-1BB CAR T cell product administered at equal target doses of CD8+ and CD4+ CAR+ T cells. An interim analysis from the OUTREACH study (NCT03744676) observed lower HCRU with outpatient vs inpatient administration (Bachier et al. J Clin Oncol 2020;38:8037). The patient journey after CAR T cell therapy administration may differ for patients with outpatient vs inpatient monitoring and may result in varying costs of care. This study estimated the cost of postinfusion monitoring by site of care for patients with R/R LBCL who received third-line or later treatment with liso-cel in the TRANSCEND NHL 001 (TRANSCEND; NCT02631044) and OUTREACH clinical trials. Methods: This retrospective study analyzed HCRU reported in clinical trial databases from TRANSCEND and OUTREACH. A 2-step microcosting method was used to identify key HCRU and to estimate postinfusion costs: (1) HCRU was analyzed from the index date (day of liso-cel infusion) through the 6-month follow-up; and (2) costs were applied to each HCRU. HCRU included standard inpatient and intensive care unit (ICU) length of stay (LOS), diagnostics (laboratory work and imaging), procedures (dialysis and intubation), and medications (supportive care, prophylactic treatment, and adverse event management). Unit costs were obtained from the health care system (provider) perspective and adjusted to 2020 US dollars. Cost per standard inpatient day ($2,542) was estimated from Healthcare Cost and Utilization Project databases, and cost per ICU day ($7,556) was sourced from Dasta et al (Crit Care Med. 2005;33:1266-77). All medication costs were obtained from REDBOOK (IBM Micromedex) using wholesale acquisition costs. Diagnostic and procedure costs were obtained from the Centers for Medicare & Medicaid Services laboratory fee schedule, physician fee schedule, or outpatient prospective payment system. A payment-to-cost ratio was applied to Medicare payment rates to estimate unit costs. Costs were adjusted to reflect the site of care where the HCRU occurred. A cost ratio was applied to adjust costs from the physician's office/community oncology clinic to the hospital outpatient department (Winfield, Muhlestein, Leavitt Partners; 2017) and from outpatient to inpatient (Meisenberg et al. Bone Marrow Transplant. 1998;21:927-32). Costs were aggregated by HCRU category, specifically medications, diagnostics, procedures, and facility costs. An average total cost by post-liso-cel infusion month was calculated for patients with ongoing status in that month (patients censored due to data cutoff were not included). Analyses were stratified by site of postinfusion monitoring (inpatients vs outpatients). Results: A total of 303 patients with R/R LBCL across the 2 trials received liso-cel and postinfusion monitoring (inpatients, n = 256; outpatients, n = 47). HCRU and LOS, including standard inpatient and ICU days, are shown in the Table. Inpatients had higher rates of inpatient stays (<100% vs 62%) and tocilizumab use (for CRS and/or NE; 20% vs 9%) than outpatients, respectively. Rates of ICU admission, corticosteroid use, vasopressor use, dialysis, and intubation were similar between groups. Median and average LOS in standard inpatient and ICU settings were higher among inpatients. Median (range) total LOS for inpatients and outpatients was 15 (0-88) and 4 (0-77) days, respectively. The estimated mean postinfusion cost of care was $89,535 for inpatients and $36,702 for outpatients. Over 6 months, most costs were incurred in the first month after infusion ($50,369 [56%] for inpatients and $19,837 [54%] for outpatients). Costs were largely driven by facility costs, namely standard inpatient and ICU stays (Figure). Conclusions: Lower overall HCRU was observed with outpatient liso-cel postinfusion monitoring, primarily due to hospitalizations, which resulted in a mean 6-month cost savings of $52,833 (59%) compared with inpatient monitoring. These results are based on national average costs and may not be generalizable to specific institutions. Disclosures Palomba: Regeneron: Research Funding; Juno Therapeutics, a Bristol-Meyers Squibb Company: Honoraria, Research Funding; Genentech: Research Funding; Merck: Honoraria; Novartis: Honoraria; Celgene: Honoraria; Pharmacyclics: Honoraria. Jun:Bristol-Myers Squibb Company: Current Employment, Current equity holder in publicly-traded company. Garcia:Bristol-Myers Squibb Company: Current equity holder in publicly-traded company; Juno Therapeutics, a Bristol-Myers Squibb Company: Current Employment. Lymp:Bristol-Myers Squibb Company: Current equity holder in publicly-traded company; Juno Therapeutics, a Bristol-Myers Squibb Company: Current Employment. McGarvey:Pfizer, Inc.: Ended employment in the past 24 months; BluePath Solutions: Current Employment. Gitlin:BMS: Research Funding. Pelletier:BMS: Current Employment, Current equity holder in publicly-traded company. Nguyen:BluePath Solutions: Current Employment.

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Treatment with Acalibrutinib, Ibrutinib and CD19 CAR T Cells Restore the Number of Granulocytic Myeloid Derived Supressor Cells in CLL-Bearing Mice

Blood ◽

10.1182/blood-2019-126697 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 3032-3032

Author(s):

Arantxa Romero-Toledo ◽

Robin Sanderson ◽

John G. Gribben

Keyword(s):

T Cells ◽

T Cell ◽

Cell Population ◽

Research Funding ◽

Cell Function ◽

Car T Cells ◽

Car T Cell ◽

T Cell Function ◽

Car T ◽

Secondary Lymphoid Organs

The complex crosstalk between malignant chronic lymphocytic leukemia (CLL) cells and the tumor microenvironment (TME) is not fully understood. CLL is associated with an inflammatory TME and T cells exhibit exhaustion and multiple functional defects, fully recapitulated in Eµ-TCL1 (TCL1) mice and induced in healthy mice by adoptive transfer (AT) of murine CLL cells, making it an ideal model to test novel immunotherapies for this disease. Myeloid-derived suppressor cells (MDSCs), a non-leukemic cell type within the TME, are immature myeloid cells with the ability to suppress T cell function and promote Treg expansion. In humans, CLL cells can induce conversion of monocytes to MDSCs provoking their accumulation in peripheral blood (PB). MDSCs include two major subsets granulocytic (Gr) and monocytic (M)-MDSC. In mice, Gr-MDSCs are defined as CD11b+Ly6G+Ly6Clo and M-MDSC as CD11b+Ly6G-Ly6Chi. Both murine and human MDSCs express BTK. We observed that in CLL-bearing mice, MDSCs cells are lost in PB as disease progresses. Treatment with both BTK inhibitors (BTKi), ibrutinib (Ibr) and acalabrutinib (Acala), result in shift of T cell function from Th2 towards Th1 polarity and increase MDSC populations in vivo. We aimed to determine whether combination treatment with BTKi and chimeric antigen receptor (CAR) T cells renders recovery of the MDSC population in CLL-bearing mice. To address this question we designed a two-part experiment, aiming to mimic the clinically relevant scenario of pre-treatment of CLL with BTKi to improve CAR T cell function. Part 1 of our experiment consisted of 4 groups (n=12) of 2.5 month old C57/Bl6 mice. Three groups had AT with 30x106 TCL1 splenocytes. A fourth group of WT mice remained CLL-free as a positive control and donors for WT T cells. When PB CLL load reached >10% (day 14) animals were randomized to either Ibr or Acala at 0.15 mg/l in 2% HPBC or no treatment for 21 days. All animals from part 1 were culled at day 35 post-AT and splenic cells were isolated, analyzed and used to manufacture CAR T cells. WT, CLL, Ibr and Acala treated T cells were activated and transduced with a CD19-CD28 CAR to treat mice in part 2. Here, 50 WT mice were given AT with 20x106 TCL1 splenocytes for CLL engraftment. All mice were injected with lymphodepleting cyclophosphamide (100mg/kg IP) one day prior to IV CAR injection. At day 21 post-AT, mice were treated with WT CAR, CLL CAR, IbrCAR, AcalaCAR or untransduced T cells. MDSC sub-populations were monitored weekly in PB and SP were analysed by flow cytometry. As malignant CD19+CD5+ cells expands in PB, the overall myeloid (CD19-CD11b+) cell population was not affected, but MDSCs significantly decreased (p<0.0001). Treatment with Acala, but not Ibr restores total MDSCs. However, MDSC impairment occurs in the Gr- but not M- MDSC population and both Acala and Ibr restores this population (Figure 1a). When we examined the spleen, treatment with both Ibr (p<0.001) and Acala (p<0.001) reduced CD5+CD19+ cells, whereas neither BTKi affected the overall myeloid (CD19-CD11b+) cell population. Gr-MDSCs were restored by both treatments whilst M-MDSCs were only restored after Ibr treatment (p<0.001 in each case). In part 2 of this experiment we observed that treatment with all CAR-T cell groups provokes the clearance of all CD19+CD5+ cells. The overall CD19-CD11b+ population stays the same across all mice groups 35 days after treatment in PB with any group of CAR and untransduced T cells. Overall MDSC population is maintained following all CAR T cells compared to CLL-bearing mice (p<0.0001) and it is the Gr- but not the M- MDSC population which is recovered in PB (Figure 1b). These parts of the experiments can of course be influenced by treatment with cyclophosphamide. We conclude that novel therapies for CLL treatment have an effect not only in CLL cells but also in non-malignant cell components of the TME. In this animal model of CLL, the rapid expansion of CLL cells in PB and secondary lymphoid organs provokes loss of MDSC, particularly the Gr-MDSC subpopulation is affected. Treatment with BTKi and CAR T cells provokes clearance of CLL cells in PB and spleen allowing MDSC recovery; suggesting this may be BTK and ITK independent. We continue to explore secondary lymphoid organs to further characterize the shift of the CLL microenvironment from an immunosuppressive to an immune effective one and its impact on immune function in this model. Disclosures Sanderson: Kite/Gilead: Honoraria. Gribben:Celgene: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Research Funding; Acerta/Astra Zeneca: Consultancy, Honoraria, Research Funding.

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