Sierra Clinical Trial Dosimetry Results Support Low Dose Anti-CD45 Iodine (131I) Apamistamab [Iomab-B] for Targeted Lymphodepletion Prior to Adoptive Cell Therapy

Introduction Nearly all adoptive cell therapies currently being evaluated in the clinic, including CAR-T, TIL, and TCR-based cell therapies, require lymphodepletion to remove cellular cytokine sinks and create a favorable cytokine environment for the incoming transferred cells to proliferate. Targeted conditioning with an antibody radio-conjugate directed to CD45 represents a promising and potentially more effective alternative to the commonly used fludarabine/cyclophosphamide chemotherapy lymphodepletion regimen. Methods SIERRA is an ongoing Phase 3 multicenter trial evaluating anti-CD45 Iodine (131I) Apamistamab [Iomab-B] as targeted conditioning prior to HCT in active, relapsed or refractory acute myeloid leukemia. Prior to administration of the therapeutic dosage, dosimetry is performed using a tracer amount of Iomab-B (range from 7-20 mCi, median 10 mCi) in an out-patient setting to calculate the appropriate patient-specific therapeutic infusion. Blood sample analysis from 57 evaluable Iomab-B treated patients collected pre-dosimetric infusion (Pre-DI), post-dosimetric infusion (Post-DI), day 1 post-dosimetric infusion (D1 post-DI), and pre-therapeutic infusion (Pre-TI, range 6-14 days post-dosimetry) was assessed to determine if residual Iomab-B had any significant effect on blood counts in support of its use as a transient targeted lymphodepletion agent. Results From these data, a significant but transient decrease in lymphocytes and white blood cells was observed compared to pre-DI values. An 85% decrease of lymphocytes was observed at the post-DI time point, a 67% decrease at day 1 post-DI, and a 43% decrease at the time of therapeutic infusion. Peripheral blasts were also transiently decreased at the post-DI time point (35%), indicating that low dose Iomab-B may exert an anti-tumor effect in these patients. Interestingly, the levels of platelets, hematocrit, and neutrophils were unchanged at the Pre-TI time point compared to Pre-DI, reflecting the comparatively lower surface antigen levels of CD45 on these cell types. In addition, data from a subset of treated patients (n=25) was used to calculate the radiation absorbed dose to bone marrow to determine an appropriate amount of Iomab-B that would not impart more than 2 Gy, a threshold that is considered to be non-myeloablative. This analysis determined that 75 mCi Iomab-B could be administered as a non-myeloablative amount and has been proposed as the starting dose for a clinical trial using Iomab-B for targeted lymphodepletion prior to CAR-T. Additional calculations were performed to model the clearance of Iomab-B to determine at what time post-infusion a CAR-T could be administered without the amount of residual radiation to bone marrow exceeding a safe level (0.25 Gy). Based on clinical data from the SIERRA trial, the average effective half-time of Iomab-B was 45.1 hours and the time frame for CAR-T administration following 75 mCi of Iomab-B was 136 hours (5.7 days). Given that administration of radiopharmaceuticals often requires special safety precautions, the proposed range of doses for Iomab-B is considered an outpatient infusion without the need for isolation. Conclusions Despite the importance of lymphodepletion prior to adoptive cell therapies, there has been very little optimization of this step. Clinical data collected using a low dose of Iomab-B for dosimetry has demonstrated that this method of lymphodepletion is specifically targeted to CD45+ immune cells, may have an anti-tumor effect, and can be administered in an outpatient setting. These clinical and logistical attributes are attractive characteristics for lymphodepletion and supportive of using Iomab-B as a novel lymphodepletion regimen prior to adoptive cell therapies such as CAR-T. Table Disclosures Nath: Astellas: Consultancy; Daiichi Sankyo: Consultancy; Actinium: Consultancy. Geoghegan:Actinium Pharmaceuticals: Employment. Spross:Actinium Pharmaceuticals: Employment, Equity Ownership. Lichtenstein:Actinium Pharmaceuticals: Employment, Equity Ownership. Konerth:Versant Medical Physics and Radiation Safety: Consultancy. Fisher:Versant Medical Physics and Radiation Safety: Employment. Liang:Actinium Pharmaceuticals: Employment. Ludwig:Actinium Pharmaceuticals: Employment, Equity Ownership. Reddy:Actinium Pharmaceuticals: Employment. Berger:Actinium Pharmaceuticals, Inc: Employment, Equity Ownership. Gyurkocza:Actinium Pharmaceuticals: Research Funding.

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Preclinical Evaluation of ALLO-819, an Allogeneic CAR T Cell Therapy Targeting FLT3 for the Treatment of Acute Myeloid Leukemia

Blood ◽

10.1182/blood-2019-129025 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 3921-3921 ◽

Cited By ~ 1

Author(s):

Cesar Sommer ◽

Hsin-Yuan Cheng ◽

Yik Andy Yeung ◽

Duy Nguyen ◽

Janette Sutton ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Target Cells ◽

Employment Equity ◽

T Cell Therapy ◽

Cell Therapies ◽

Car T Cells ◽

Car T Cell ◽

Car T ◽

Equity Ownership

Autologous chimeric antigen receptor (CAR) T cells have achieved unprecedented clinical responses in patients with B-cell leukemias, lymphomas and multiple myeloma, raising interest in using CAR T cell therapies in AML. These therapies are produced using a patient's own T cells, an approach that has inherent challenges, including requiring significant time for production, complex supply chain logistics, separate GMP manufacturing for each patient, and variability in performance of patient-derived cells. Given the rapid pace of disease progression combined with limitations associated with the autologous approach and treatment-induced lymphopenia, many patients with AML may not receive treatment. Allogeneic CAR T (AlloCAR T) cell therapies, which utilize cells from healthy donors, may provide greater convenience with readily available off-the-shelf CAR T cells on-demand, reliable product consistency, and accessibility at greater scale for more patients. To create an allogeneic product, the TRAC and CD52 genes are inactivated in CAR T cells using Transcription Activator-Like Effector Nuclease (TALEN®) technology. These genetic modifications are intended to minimize the risk of graft-versus-host disease and to confer resistance to ALLO-647, an anti-CD52 antibody that can be used as part of the conditioning regimen to deplete host alloreactive immune cells potentially leading to increased persistence and efficacy of the infused allogeneic cells. We have previously described the functional screening of a library of anti-FLT3 single-chain variable fragments (scFvs) and the identification of a lead FLT3 CAR with optimal activity against AML cells and featuring an off-switch activated by rituximab. Here we characterize ALLO-819, an allogeneic FLT3 CAR T cell product, for its antitumor efficacy and expansion in orthotopic models of human AML, cytotoxicity in the presence of soluble FLT3 (sFLT3), performance compared with previously described anti-FLT3 CARs and potential for off-target binding of the scFv to normal human tissues. To produce ALLO-819, T cells derived from healthy donors were activated and transduced with a lentiviral construct for expression of the lead anti-FLT3 CAR followed by efficient knockout of TRAC and CD52. ALLO-819 manufactured from multiple donors was insensitive to ALLO-647 (100 µg/mL) in in vitro assays, suggesting that it would avoid elimination by the lymphodepletion regimen. In orthotopic models of AML (MV4-11 and EOL-1), ALLO-819 exhibited dose-dependent expansion and cytotoxic activity, with peak CAR T cell levels corresponding to maximal antitumor efficacy. Intriguingly, ALLO-819 showed earlier and more robust peak expansion in mice engrafted with MV4-11 target cells, which express lower levels of the antigen relative to EOL-1 cells (n=2 donors). To further assess the potency of ALLO-819, multiple anti-FLT3 scFvs that had been described in previous reports were cloned into lentiviral constructs that were used to generate CAR T cells following the standard protocol. In these comparative studies, the ALLO-819 CAR displayed high transduction efficiency and superior performance across different donors. Furthermore, the effector function of ALLO-819 was equivalent to that observed in FLT3 CAR T cells with normal expression of TCR and CD52, indicating no effects of TALEN® treatment on CAR T cell activity. Plasma levels of sFLT3 are frequently increased in patients with AML and correlate with tumor burden, raising the possibility that sFLT3 may act as a decoy for FLT3 CAR T cells. To rule out an inhibitory effect of sFLT3 on ALLO-819, effector and target cells were cultured overnight in the presence of increasing concentrations of recombinant sFLT3. We found that ALLO-819 retained its killing properties even in the presence of supraphysiological concentrations of sFLT3 (1 µg/mL). To investigate the potential for off-target binding of the ALLO-819 CAR to human tissues, tissue cross-reactivity studies were conducted using a recombinant protein consisting of the extracellular domain of the CAR fused to human IgG Fc. Consistent with the limited expression pattern of FLT3 and indicative of the high specificity of the lead scFv, no appreciable membrane staining was detected in any of the 36 normal tissues tested (n=3 donors). Taken together, our results support clinical development of ALLO-819 as a novel and effective CAR T cell therapy for the treatment of AML. Disclosures Sommer: Allogene Therapeutics, Inc.: Employment, Equity Ownership. Cheng:Allogene Therapeutics, Inc.: Employment, Equity Ownership. Yeung:Pfizer Inc.: Employment, Equity Ownership. Nguyen:Allogene Therapeutics, Inc.: Employment, Equity Ownership. Sutton:Allogene Therapeutics, Inc.: Employment, Equity Ownership. Melton:Allogene Therapeutics, Inc.: Employment, Equity Ownership. Valton:Cellectis, Inc.: Employment, Equity Ownership. Poulsen:Allogene Therapeutics, Inc.: Employment, Equity Ownership. Djuretic:Pfizer, Inc.: Employment, Equity Ownership. Van Blarcom:Allogene Therapeutics, Inc.: Employment, Equity Ownership. Chaparro-Riggers:Pfizer, Inc.: Employment, Equity Ownership. Sasu:Allogene Therapeutics, Inc.: Employment, Equity Ownership.

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A Phase 1/2 Study of the Second Generation Selective Inhibitor of Nuclear Export (SINE) Compound, KPT-8602, in Patients with Relapsed Refractory Multiple Myeloma

Blood ◽

10.1182/blood.v128.22.4509.4509 ◽

2016 ◽

Vol 128 (22) ◽

pp. 4509-4509 ◽

Cited By ~ 4

Author(s):

R. Frank Cornell ◽

Adriana C Rossi ◽

Rachid Baz ◽

Craig C Hofmeister ◽

Chaim Shustik ◽

...

Keyword(s):

Clinical Trial ◽

Board Of Directors ◽

Nuclear Export ◽

Research Funding ◽

Low Dose ◽

Phase 1 ◽

Single Agent ◽

Employment Equity ◽

Advisory Committees ◽

Equity Ownership

Abstract Introduction - Inhibition of Exportin 1 (XPO1) is a novel treatment approach for multiple myeloma (MM). XPO1 mediates the nuclear export of cell-cycle regulators and tumor suppressor proteins leading to their functional inactivation. In addition, XPO1 promotes the export and translation of the mRNA of key oncoproteins (e.g. c-MYC, BCL-2, Cyclin D). XPO1 overexpression occurs in solid and hematological malignancies, including MM and is essential for MM cell survival. Selinexor, the first oral SINE compound, has shown promising anti-MM activity in phase 1 studies but has been associated with gastrointestinal and constitutional toxicities including nausea, anorexia and fatigue. KPT-8602 is a second generation oral SINE compound with similar in vitro potency to selinexor, however, has substantially reduced brain penetration compared with selinexor, and demonstrated markedly improved tolerability with minimal anorexia and weight loss in preclinical toxicology studies. In murine models of MM, KPT-8602 can be dosed daily (QDx5) with minimal anorexia and weight loss. We have therefore initiated a phase 1/2 first-in-human clinical trial. Methods - This phase 1/2 clinical trial was designed to evaluate KPT-8602 as a single agent and in combination with low dose dexamethasone (dex) in patients (pts) with relapsed / refractory MM (RRMM). KPT-8602 is dosed orally (QDx5) for a 28-day cycle with a starting dose of 5 mg. Low dose dex (20 mg, twice weekly) is allowed after cycle 1 if at least a minimal response (MR) is not observed. The primary objective is to evaluate the safety and tolerability including dose-limiting toxicity (DLT), determine the maximum tolerated dose (MTD), the recommended Phase 2 dose (RP2D), and evidence for anti-MM activity for KPT-8602 single agent and in combination with dex. The pharmacokinetic (PK) and pharmacodynamic (PDn; XPO1 mRNA) profile of KPT-8602 will also be determined. PDn predictive biomarker analysis and ex vivo drug response assays are underway using tumor cells from bone marrow aspirates before treatment, during and at relapse. These analyses include cell death pathway assays by flow and nuclear/cytoplasmic localization of XPO1, NF-ƙB, IƙBα, IKKα, NRIF and p53 by imaging flow and IHC. Results - As of 01-Aug-2016, 6 pts 2 M/4 F, (median of 6 prior treatment regimens, median age of 71) with RRMM have been enrolled. Common related grade 1/2 adverse events (AEs) include thrombocytopenia (3 pts), nausea (2 pts) and diarrhea (2 pts). Grade 3 AEs include neutropenia (1 pt) and dehydration (1 pt). No grade 4 or 5 AEs have been reported. No DLTs have been observed and the MTD has not been reached. 5 pts were evaluable for responses (1 pt pending evaluation): 1 partial response, 1 minimal response, and 3 stable disease; no pts have progressed on therapy with the longest on for >5 months. The PK properties following oral administration showed that 5 mg of KPT-8602 was rapidly absorbed (mean tmax= 1 hr, mean Cmax= 30.6 ng/mL). The mean AUCinf was calculated to be 141 ng•hr/mL. After tmax, KPT-8602 declined at an estimated mean t½ of 4 hr. At the same dose level, XPO1 mRNA expression was the highest (~2.5 fold) at 8 hr post dose. Conclusions - Oral KPT-8602 is well tolerated in heavily pretreated pts with RRMM. Gastrointestinal and constitutional toxicities observed with twice weekly selinexor have not been observed with 5x/week KPT-8602, including in pts on study for >4 months. PK was predictable and in line with selinexor. These early results show encouraging disease control with pts remaining on therapy. Enrollment is on-going. Disclosures Rossi: Takeda: Speakers Bureau; Janssen: Speakers Bureau; Onyx: Research Funding, Speakers Bureau; Celgene: Consultancy, Speakers Bureau. Baz:Takeda/Millennium: Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Research Funding; Signal Genetics: Research Funding; Bristol-Myers Squibb: Research Funding; Merck: Research Funding; Novartis: Research Funding. Hofmeister:Karyopharm Therapeutics: Research Funding; Arno Therapeutics, Inc.: Research Funding; Signal Genetics, Inc.: Membership on an entity's Board of Directors or advisory committees; Janssen: Pharmaceutical Companies of Johnson & Johnson: Research Funding; Incyte, Corp: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; Takeda Pharmaceutical Company: Research Funding; Teva: Membership on an entity's Board of Directors or advisory committees. Shustik:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Millenium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Richter:Amgen: Consultancy, Speakers Bureau; Takeda: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Jannsen: Speakers Bureau. Chen:Janssen: Honoraria, Research Funding; Takeda: Research Funding; Celgene: Honoraria, Research Funding. Vogl:Takeda: Consultancy, Research Funding; Celgene: Consultancy; GSK: Research Funding; Calithera: Research Funding; Teva: Consultancy; Karyopharm: Consultancy; Acetylon: Research Funding; Constellation: Research Funding. Shacham:Karyopharm Therapeutics: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Baloglu:Karyopharm Therapeutics: Employment, Equity Ownership. Senapedis:Karyopharm Therapeutics: Employment, Equity Ownership. Ellis:Karyopharm Therapeutics: Employment, Equity Ownership. Friedlander:Karyopharm Therapeutics: Employment. Choe-Juliak:Karyopharm Therapeutics: Employment. Sullivan:Karyopharm Therapeutics: Research Funding. Kauffman:Karyopharm Therapeutics Inc: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees.

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High Rates of Minimal Residual Disease-Negative (MRD−) Complete Responses (CR) in Adult and Pediatric and Patients With Relapsed/Refractory Acute Lymphoblastic Leukemia (R/R ALL) Treated With KTE-C19 (Anti-CD19 Chimeric Antigen Receptor [CAR] T Cells): Preliminary Results of the ZUMA-3 and ZUMA-4 Trials

Blood ◽

10.1182/blood.v128.22.2803.2803 ◽

2016 ◽

Vol 128 (22) ◽

pp. 2803-2803 ◽

Cited By ~ 17

Author(s):

Bijal Shah ◽

Van Huynh ◽

Leonard S. Sender ◽

Daniel W. Lee ◽

Januario E. Castro ◽

...

Keyword(s):

T Cells ◽

Research Funding ◽

Low Dose ◽

Lymphoblastic Leukemia ◽

Phase 1 ◽

Employment Equity ◽

Car T Cells ◽

Car T ◽

Equity Ownership ◽

Support Research

Abstract Background: Acute lymphoblastic leukemia (ALL) exhibits a bimodal age distribution with 60% of cases occurring in children and adolescents (<20 y) and 25% in older adults (>45 y; Howlader SEER Cancer Statistics 2015). Most adults and 15-20% of children will relapse following initial therapy with subsequent poor outcomes. (Bassan, JCO 2012; Locatelli, Blood 2012). Promising results have been observed in studies of anti-CD19 CAR T cells in patients with B cell malignancies, including those treated with KTE-C19, a CD28/CD3ζ anti-CD19 CAR T cell studied in the multicenter ZUMA-1 trial (Neelapu ASCO 2016). However, studies of anti-CD19 CAR T cell therapy in R/R ALL have also observed high incidences of severe CRS in patients with high leukemic burden (Lee, Lancet 2015; Maude NEJM 2014). We present a preliminary analysis of the phase 1 portions of ZUMA-3 and ZUMA-4 which to date have enrolled adult and pediatric patients, respectively with high leukemic burden (M3 marrow). Methods: The primary objective of phase 1 of these multicenter trials is to evaluate the safety of KTE-C19. Eligible patients with R/R ALL are aged ≥18 y (ZUMA-3) or 2-21 y (ZUMA-4) with ≥25% marrow blasts, and adequate renal, hepatic, and cardiac function. Patients are required to have an Eastern Cooperative Oncology Group performance score 0-1 (ZUMA-3) or a Lansky or Karnofsky performance status of >80% (ZUMA-4). Patients with Ph+ ALL and low-burden central nervous system disease are eligible. Patients with Burkitt lymphoma or chronic myeloid leukemia in blast crisis, extramedullary disease only, active graft-versus-host disease, or clinically significant infection are not eligible. KTE-C19 is administered at a target dose of either 1 or 2 × 106 anti-CD19 CAR T cells/kg after low-dose conditioning with fludarabine (25 mg/m2/day for 3 days) and cyclophosphamide (900 mg/m2/day [CyFlu]; Wayne ASCO 2016; Shah ESMO 2016). Results: As of July 8, 2016, 6 patients have enrolled and 5 patients (3 adult and 2 pediatric) have been treated with KTE-C19. KTE-C19 was successfully manufactured in a centralized, streamlined 6-8-day process for 5 patients with approximately a 2-week turnaround time from the time of apheresis to delivery of KTE-C19 to site for patient infusion (Choi, ASGCT 2016). In one 2-year-old patient with peripheral white blood cells >150,000/μL and >99% leukemic blasts in the apheresis collection, KTE-C19 could not be manufactured. All 5 treated patients had high burden disease with a median 85% of marrow blasts (range, 48%-100%) at screening. All 5 patients received bridging chemotherapy prior to dosing with KTE-C19. No patient experienced a dose-limiting toxicity. Cytokine release syndrome (CRS) was reported in all adult (grade 1, n=1; grade 2, n=2) and pediatric (grade 2, n=2) patients; neurotoxicity (NT) was reported in adults only (grade 3, n=2; grade 4, n=1). CRS and NT were successfully managed to resolution with either tocilizumab, corticosteroids, and/or siltuximab in addition to other supportive care for all 5 patients. MRD- remission has been observed in all 5 patients who received KTE-C19 by day 28, with some remissions occurring as early as day 7. Four of 5 patients have had a CR/CR with partial hematologic recovery to date, and 1 of 5 patients with MRD- remission was showing recovering counts. CAR T cells expanded in blood within 2 weeks after infusion and were also detected in bone marrow and/or cerebrospinal fluid. Additional patients and clinical and correlative biomarker data will be presented. Conclusions: The administered dose of KTE-C19 after low-dose CyFlu conditioning has been tolerable and to date appears safe for further analysis in adult and pediatric patients with high leukemic burden R/R ALL. Initial results demonstrate promising efficacy, and the central manufacturing process is deemed feasible. The phase 1 portions of ZUMA-3 and ZUMA-4 are ongoing with planned expansion to phase 2. Clinical trial information: NCT02614066 (ZUMA-3); NCT02625480 (ZUMA-4). Disclosures Shah: Pfizer: Consultancy, Speakers Bureau; Bayer: Honoraria, Speakers Bureau; Plexus Communications: Honoraria; Rosetta Genomics: Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Baxalta: Honoraria, Speakers Bureau. Lee:Juno: Honoraria. Wierda:Novartis: Research Funding; Abbvie: Research Funding; Acerta: Research Funding; Gilead: Research Funding; Genentech: Research Funding. Schiller:Incyte Corporation: Research Funding. Gökbuget:Pfizer: Honoraria, Research Funding; Amgen: Honoraria, Research Funding. Sabatino:Kite: Employment, Equity Ownership. Bot:Kite Pharma: Employment, Equity Ownership. Rossi:Kite Pharma: Employment, Equity Ownership. Jiang:Kite Pharma: Employment, Equity Ownership. Navale:Kite Pharma: Employment, Equity Ownership. Stout:Kite Pharma: Employment, Equity Ownership. Aycock:Kite Pharma: Employment, Equity Ownership. Wiezorek:Kite Pharma: Employment, Equity Ownership. Jain:Kite Pharma: Employment, Equity Ownership. Wayne:Spectrum Pharmaceuticals: Honoraria, Other: Travel Support, Research Funding; Kite Pharma: Honoraria, Other: Travel support, Research Funding; Pfizer: Consultancy, Honoraria, Other: Travel Support; Medimmune: Honoraria, Other: Travel Support, Research Funding; NIH: Patents & Royalties.

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Superior Efficacy of CAR-T Cells Using Marrow-Infiltrating Lymphocytes (MILsTM) As Compared to Peripheral Blood Lymphocytes (PBLs)

Blood ◽

10.1182/blood-2019-130629 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 4437-4437 ◽

Cited By ~ 2

Author(s):

Eric R. Lutz ◽

Srikanta Jana ◽

Lakshmi Rudraraju ◽

Elizabeth DeOliveira ◽

Jing Zhou ◽

...

Keyword(s):

Multiple Myeloma ◽

Bone Marrow ◽

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Employment Equity ◽

Car T Cells ◽

Car T ◽

Equity Ownership

Background The type of T cell used in generating chimeric antigen receptor (CAR) T cells is an important choice. Evidence suggests that T cells that are early in the effector/memory differentiation pathway with more stemness and greater potential to persist are better than more differentiated T cells with less stemness that are more readily exhausted and have less potential to persist. Marrow-infiltrating Lymphocytes (MILsTM) is a novel form of adoptive T cell therapy composed of patient-autologous, polyclonal CD4 and CD8 T cells that are activated and expanded from the bone marrow. Genetically unmodified MILsTM have demonstrated antitumor activity in patients with multiple myeloma and are being developed for several other tumor types, including non-small cell lung cancer and other solid tumors. Distinguishing features of bone marrow T cells used to produce MILsTM include their memory phenotype, inherent tumor antigen-specificity, higher CD8:CD4 ratio and ability to persist long-term when compared to peripheral blood lymphocytes (PBLs) which is the T cell source used to produce currently approved CAR-T therapies. Based on these differences, we hypothesize that MILsTM provide a more robust and better fit platform for CAR-T therapy compared to PBLs. Using a CD38-specific, 4-1BB/CD3z-signaling CAR as an initial model, we have demonstrated the feasibility of producing CAR-modified MILsTM (CAR-MILsTM) and showed that CAR-MILsTM demonstrate superior killing in vitro compared to CAR-T cells generated from patient-matched PBLs (CAR-PBLs). Herein, we build on our previous data and add a second BCMA-specific CAR model. We use the two multiple myeloma model systems to compare cytolytic potential, functionality, and expression of phenotypic markers of memory, stemness and exhaustion between patient-matched CAR-MILsTM and CAR-PBLs. Methods Matched pairs of CAR-MILsTM and CAR-PBLs were produced from the bone marrow and blood of multiple myeloma patients. Two different in vitro cytotoxicity assays, the RTCA xCelligence real-time impedance and FACS assays, were used to evaluate antigen-specific killing of target tumor cells. Functionality of CD4 and CD8 CAR-T cells, at the single-cell level, was evaluated by measuring the secretion of 32 cytokines and chemokines following in vitro antigen-specific stimulation using IsoPlexis IsoCode chips and analyzed using IsoPeak. Expression of markers of T cell memory (CD45RO & CCR7/CD62L), stemness (CD27) and exhaustion (PD1 & TIM3) on CAR-MILsTM and CAR-PBLs prior to and following antigen-specific stimulation was evaluated by flow-cytometry (FACS). Results CAR-MILsTM demonstrated superior killing of tumor target cells in vitro, regardless of the antigen specificity of the CAR, when compared to matched CAR-PBLs and this superiority persisted even upon repeated antigen encounter - a factor that may be critical in guaranteeing better anti-tumor efficacy and persistence. CAR-MILsTM demonstrated increased polyfunctionality (secretion of 2+ cytokines per cell) and an increased polyfunctional strength index (PSI) following antigen-stimulation compared to CAR-PBL in both CD4 and CD8 T cells. The enhanced PSI in CAR-MILsTM was predominately mediated by effector, stimulatory and chemoattractive proteins associated with antitumor activity including Granzyme B, IFNg, IL-8, MIP1a and MIP1b. Coincidentally, increased PSI and enhanced secretion of these same proteins was reported to be associated with improved clinical responses in patients with Non-Hodgkin lymphoma treated with CD19-specific CAR-T therapy. Expression of memory markers on CD4 and CD8 T cells were similar in CAR-MILsTM and CAR-PBLs both prior to and following antigen-stimulation. Although expression of CD27, PD1 and TIM3 were similar at baseline, CAR-MILs maintained higher levels of CD27 and lower levels of PD1 and TIM3 compared to CAR-PBLs following antigen-stimulation in both CD4 and CD8 T cells. Conclusions Collectively, our data suggest that CAR-MILsTM have several advantages over CAR-PBLs, including increased cytolytic potential, enhanced polyfunctionality, increased stemness and less exhaustion. Based on these differences and the inherent antitumor properties of MILsTM, we speculate that CAR-MILsTM would be more potent and effective than currently approved CAR-T products derived from PBLs. Disclosures Lutz: WindMIL Therapeutics: Employment, Equity Ownership. Jana:WindMIL Therapeutics: Employment, Equity Ownership. Rudraraju:WindMIL Therapeutics: Employment, Equity Ownership. DeOliveira:WindMIL Therapeutics: Employment, Equity Ownership. Zhou:Isoplexis: Employment, Equity Ownership. Mackay:Isoplexis: Employment, Equity Ownership. Borrello:Aduro: Patents & Royalties: intellectual property on allogeneic MM GVAX; BMS: Consultancy; WindMIL Therapeutics: Equity Ownership, Patents & Royalties, Research Funding; Celgene: Honoraria, Research Funding, Speakers Bureau. Noonan:WindMIL Therapeutics: Employment, Equity Ownership, Patents & Royalties; Aduro: Patents & Royalties: intellectual property on allogeneic MM GVAX.

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Developing a Novel Anti-Bcma CAR-T for Relapsed or Refractory Multiple Myeloma

Blood ◽

10.1182/blood-2019-125372 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 50-50 ◽

Cited By ~ 1

Author(s):

Xin Yao ◽

Shigui Zhu ◽

Jiaqi Huang ◽

Xiaoyan Qu ◽

Judy Zhu ◽

...

Keyword(s):

Clinical Trial ◽

Multiple Myeloma ◽

T Cells ◽

Tumor Cells ◽

Human Monoclonal Antibody ◽

Employment Equity ◽

Early Clinical Trial ◽

Car T Cells ◽

Car T ◽

Equity Ownership

CBMG has developed C-CAR088, a novel chimeric antigen receptor (CAR)-T cell therapy targeting BCMA, which is specifically and highly expressed on multiple myeloma cells. C-CAR088 is designed to improve efficacy through increasing the specificity and reducing immunogenicity by fusing a scFv from high-affinity human monoclonal antibody to a CD3ζ/4-1BB signaling domain. In preclinical study, the human T cells transduced with the lentiviral vector encoding C-CAR088 exhibited specific functions in vitro including CAR-T proliferation, cytokine production, cytotoxicity to BCMA positive tumor cells. C-CAR088 cells were not activated by soluble BCMA protein and MM patient serums. However, they can eradicate BCMA positive tumor cells in vivo including BMCA positive multiple myeloma tumor model RPMI-8226. C-CAR088 is manufactured in a serum free, automated and digital, closed system which produce CAR-T cells with stable and high percentage of Tcm phenotype. C-CAR088 showed a very good dose dependent tumor inhibition effect and survival benefit in animal studies. A Phase 1, 3+3 dose escalation trial is being conducted in patients with r/r MM (≥ 3 prior lines, having received treatment and proteasome inhibitors (PI) and IMiD or double refractory) to assess the safety and efficacy of C-CAR088 (NCT03815383). Patients are apheresed to harvest T cells. C-CAR088 is then manufactured and administered to patients as a single intravenous dose after a standard 3-day cyclophosphamide/fludarabine conditioning regimen. As of July 5, 2019 cutoff date, 3 patients have been treated with C-CAR088 at the dose of 1.0 x 106 CAR-T cells/kg. Patients were heavily pre-treated (7 prior lines of therapy), and all failed IMiDs and proteasome inhibitor therapies. After C-CAR088 treatment, all three patients showed clinical improvement as early as two weeks post treatment. Furthermore, C-CAR088 proliferation & expansion in the peripheral blood correlated with the decrease of tumor burden. Two patients reached VGPR at 4 weeks and 8 weeks respectively, and the third patient reached PR as early as 2 weeks post C-CAR088 infusion. C-CAR088 treatment was well tolerated, no dose-limiting toxicities (DLTs), reversible Grade 1~2 CRS observed. In conclusion, early clinical trial results in patients with r/r MM for C-CAR088 support preclinical findings that the drug shows promising efficacy and manageable safety profile.The very early clinical efficacy signal at low, suboptimal dose is encouraging and compares favorably to many other anti-BCMA CAR-T products at similar dose. The promising trend needs to be confirmed by the ongoing clinical trial. Disclosures Yao: Cellular Biomedicine Group Inc: Employment, Equity Ownership. Zhu:Cellular Biomedicine Group Inc: Employment, Equity Ownership. Huang:Cellular Biomedicine Group Inc: Employment, Equity Ownership. Zhu:Cellular Biomedicine Group Inc: Employment, Equity Ownership. Wei:Cellular Biomedicine Group Inc: Employment, Equity Ownership. Lan:Cellular Biomedicine Group Inc: Employment, Equity Ownership. LV:Cellular Biomedicine Group Inc: Employment, Equity Ownership. Wu:Cellular Biomedicine Group Inc: Employment, Equity Ownership. Wang:Cellular Biomedicine Group Inc: Employment, Equity Ownership. Yang:Cellular Biomedicine Group Inc: Employment, Equity Ownership. Zheng:Cellular Biomedicine Group Inc: Employment, Equity Ownership. Zhao:Cellular Biomedicine Group Inc: Employment, Equity Ownership. Zhang:Cellular Biomedicine Group Inc: Employment, Equity Ownership. Chen:Cellular Biomedicine Group Inc: Employment, Equity Ownership. Li:Cellular Biomedicine Group Inc: Employment, Equity Ownership. Ren:Cellular Biomedicine Group Inc: Employment, Equity Ownership. Zhang:Cellular Biomedicine Group Inc: Employment, Equity Ownership. Humphries:Cellular Biomedicine Group Inc: Employment, Equity Ownership. Yao:Cellular Biomedicine Group Inc: Employment, Equity Ownership.

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CAR T Cell Therapy Targeting G Protein-Coupled Receptor Class C Group 5 Member D (GPRC5D), a Novel Target for the Immunotherapy of Multiple Myeloma

Blood ◽

10.1182/blood-2018-99-110471 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 589-589 ◽

Cited By ~ 3

Author(s):

Eric L. Smith ◽

Kimberly Harrington ◽

Mette Staehr ◽

Reed Masakayan ◽

Jon Jones ◽

...

Keyword(s):

Bone Marrow ◽

T Cells ◽

T Cell ◽

Research Funding ◽

Employment Equity ◽

Car T Cells ◽

Car T Cell ◽

Car T ◽

Equity Ownership ◽

G Protein Coupled

Abstract Early clinical results using BCMA targeted CAR T cell therapies for advanced multiple myeloma (MM) have shown promise. However, BCMA expression can be variable, and BCMA downregulation has been correlated with relapse (Brudno J. JCO. 2018; Cohen A. ASH. 2017). Targeting multiple antigens may enhance response durability. We report that the orphan seven transmembrane G protein coupled receptor, GPRC5D, is an attractive additional target for CAR T cell therapy of MM. GPRC5D mRNA expression was previously identified in bone marrow cells from patients with MM; however its protein expression could not be detected with available FACS reagents (Frigyesi I. Blood. 2014). We evaluated 83 primary marrow samples by quantitative immunofluorescence (Q-IF) for CD138, BCMA, and GPRC5D. In 98% of the samples, CD138+ cells expressed surface GPRC5D. In most samples, the majority of CD138+ cells expressed both BCMA and GPRC5D, however, in several cases the dominant CD138+ population expressed only BCMA or GPRC5D, with GPRC5D expression independent of BCMA across samples (R2=0.156; Figure 1). The potential for "on target/off tumor" binding by targeting GPRC5D was evaluated by screening 30 essential normal tissue types by IHC (n=3 donors/type) followed by validation of any positive findings by RNA in situ hybridization and quantitative PCR. Results in non-plasma cell normal tissue were consistent with prior reports of GPRC5D off target expression restricted to cells from the hair follicle, a potentially immune privileged site. We developed GPRC5D-targeted CARs considering immunogenicity, spacer length, and tonic signaling. To minimize potential anti-CAR immunity, a human B cell-derived phage display library was screened. Seven diverse and highly specific human single chain variable fragments (scFvs) were identified. 42 CARs were derived from the 7 scFvs by modifying scFv orientation (VH/VL; VL/VH) and incorporating a short, medium, or long IgG4 based spacer. To monitor CAR-mediated signaling, we transduced each CAR into a Jurkat reporter line with RFP inserted in-frame, downstream of endogenous NR4A1 (Nur77). Nur77 expression is an immediate-early, specific marker of CD3z signaling (Ashouri J. J Immunol. 2017). Using this reporter, we observed that (1) a long spacer provided enhanced antigen-dependent activation across all anti-GPRC5D CARs; and (2) the use of different scFvs resulted in vastly different levels of tonic signaling. We selected potential lead and backup constructs and evaluated CAR activity on primary human T cells. When co-cultured specifically with MM cell lines, anti-GPRC5D CAR T cells secreted a polyfunctional cytokine profile, proliferated, and effectively lysed target cells. CD138+/CD38hi primary MM bone marrow aspirate cells were also specifically lysed. In vivo efficacy of GPRC5D-targeted CAR T cells was evaluated in NSG mice engrafted with a human MM cell line (ffLuc+) bone marrow xenograft. Donor T cells were gene-modified to express anti-GPRC5D CARs with either a 4-1BB or a CD28 co-stimulatory domain and membrane-anchored Gaussia luciferase (GLuc). Compared to control CAR T cells specific for an irrelevant target, anti-GPRC5D CAR T cells with either co-stimulatory domain proliferated and homed to the site of MM (Gluc imaging), eradicated MM xenograft (ffLuc imaging), and increased survival (Figure 2). One scFv that was highly functional in our GPRC5D CAR screen was evaluated for off-target binding against either >200 G protein-coupled receptors (cell based), or >4000 human transmembrane proteins (scFv-Fc based), and demonstrated binding only to GPRC5D. Studies with murine and cynomolgus cross-reactive GPRC5D targeting CARs did not show signs of alopecia or other unexpected toxicity in either species. In a murine model of post-BCMA CAR T cell treated antigen escape (CRISPR BCMA KO of a subpopulation of MM cells), anti-GPRC5D CAR T cells rescue BCMA- relapse. These results indicate that GPRC5D will be an important target for the immunotherapy of MM. We are translating this 4-1BB-containing, human-derived, GPRC5D-targeted CAR construct to the clinic. Disclosures Smith: Celgene: Consultancy, Patents & Royalties: CAR T cell therapies for MM, Research Funding. Harrington:Juno Therapeutics, a Celgene Company: Employment, Equity Ownership. Masakayan:Agentus Inc: Employment. Jones:Juno Therapeutics, a Celgene Company: Employment, Equity Ownership. Long:Juno Therapeutics, a Celgene Company: Employment, Equity Ownership. Ghoddusi:Juno Therapeutics, a Celgene Company: Employment, Equity Ownership. Do:Juno Therapeutics, a Celgene Company: Employment, Equity Ownership. Pham:Juno Therapeutics, a Celgene Company: Employment, Equity Ownership. Wang:Eureka Therapeutics: Employment, Equity Ownership. Liu:Eureka Therapeutics, Inc.: Employment, Equity Ownership. Xu:Eureka Therapeutics: Employment, Equity Ownership. Riviere:Juno Therapeutics, a Celgene Company: Membership on an entity's Board of Directors or advisory committees, Research Funding; Fate Therapeutics Inc.: Research Funding. Liu:Eureka Therapeutics, Inc.: Employment, Equity Ownership. Sather:Juno Therapeutics, a Celgene Company: Employment, Equity Ownership. Brentjens:Juno Therapeutics, a Celgene Company: Consultancy, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding.

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NKTR-255, a Polymer-Conjugated IL-15 Enhances Antibody-Dependent Cellular Cytotoxicity Mediated By NK Cells in a B Cell Lymphoma Model

Blood ◽

10.1182/blood-2019-127771 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 5302-5302

Author(s):

Takahiro Miyazaki ◽

Saul Kivimäe ◽

Marlene Hennessy ◽

Rhoneil Pena ◽

Phi Quach ◽

...

Keyword(s):

Bone Marrow ◽

Nk Cells ◽

Survival Benefit ◽

Low Dose ◽

Nk Cell ◽

High Dose ◽

Employment Equity ◽

Equity Ownership ◽

Rpmi 8226

Background IL-15 is a cytokine that activates and provides survival benefit to T and NK cells and has great potential as an immunotherapeutic agent for the treatment of cancer. Exploiting the therapeutic value of native IL-15 has been challenging due to its unfavorable pharmacokinetic properties and poor tolerability. NKTR-255 is a polymer-conjugated IL-15 designed to retain binding affinity to the IL-15 receptor alpha chain and have decreased clearance to provide a sustained pharmacodynamics response. NKTR-255 has an enhanced immunotherapeutic effect when combined with certain targeted monoclonal antibodies that mediate tumor killing by antibody dependent cellular cytotoxicity (ADCC). Here we further characterized the effect of NKTR-255 on NK cell-mediated ADCC in a B cell lymphoma model. Methods For in vitro ADCC, NKTR-255 pre-treated human NK cells (effector cells) were co-cultured with RPMI-8226 (target cells) and with daratumumab for 3 hours. The ability of NK cells to lyse target cells was evaluated by detecting 7-AAD stained RPMI-8226. In the Daudi lymphoma model, SCID or SCID beige mice were inoculated IV with 1x107 Daudi cells on Day 0. NKTR-255 (0.3 mg/kg IV) was administered on Days 14, 21 and 28 and a single dose of antibody treatment was given on Day 14 (daratumumab 0.5 mg/kg IP). Survival rate was determined by onset of hind limb paralysis or moribundity as surrogate parameters. Concurrent vs staggered regimen assessment was conducted with NKTR-255 dosed on day 14 and daratumumab on Day 14, 17, or 21. For dose examination, high (0.5 mg/kg) and low (0.05 mg/kg) doses of daratumumab were combined with low (0.03 mg/kg) and high (0.3 mg/kg) doses of NKTR-255 in a concurrent manner. Daudi cells in the bone marrow were assessed 10 days after the NKTR-255 dose by flow cytometry. Results In vitro, NKTR-255 pre-treatment of human purified NK cells enhanced daratumumab-mediated ADCC against RPMI-8226. The ability of NKTR-255 to enhance in vitro ADCC was translated into an enhanced therapeutic efficacy of daratumumab in the Daudi lymphoma model with SCID mice. NKTR-255 combined with daratumumab synergistically provided long-term survival benefit in a NKTR-255 dose-dependent manner. To confirm the contribution of NK cells as effector cells for ADCC in vivo, the therapeutic effect of the combination treatment was assessed in the tumor model in SCID beige mice, which have a selective impairment of NK cell cytotoxic function. The long-term survival benefit by the combination treatment, which was observed in SCID mice (median survival of 27 days in control and 59.5 days in treatment), was attenuated in SCID beige mice (median survival of 23 days in control and 30 days in treatment). Concurrent vs staggered dose regimens and dose ranging for NKTR-255 and daratumumab were evaluated in the Daudi model with SCID mice to understand optimal therapeutic use of NKTR-255 in future clinical studies. Tumor depletion in bone marrow was most effective in concurrent treatment of NKTR-255 and daratumumab and three days-staggered treatment (NKTR-255 first and the antibody 3 days later). In contrast, a 7-day stagger showed no benefit of the combination in tumor depletion. Combination of low dose daratumumab and high dose NKTR-255 was equally effective in tumor depletion as a combination of high dose daratumumab and low dose NKTR-255. Conclusions NKTR-255 was shown to enhance in vivo therapeutic efficacy of daratumumab, a monoclonal antibody that mediates tumor killing by ADCC. The effect was mainly mediated by NK cells. The treatment scheduling experiments demonstrated that antibody should be present during NKTR-255-driven NK cell activation/expansion phase to efficiently deplete Daudi tumor cells in bone marrow. In addition, even low dose of daratumumab treatment showed effective tumor depletion when combined with high dose of NKTR-255. This suggests that NKTR-255 has a potential to expand the therapeutic window of existing tumor-targeted antibodies to patients with, for example, low antibody concentration in target tumor site or low expression of tumor antigen. Disclosures Miyazaki: Nektar Therapeutics: Employment, Equity Ownership. Kivimäe:Nektar Therapeutics: Employment, Equity Ownership. Hennessy:Nektar Therapeutics: Employment, Equity Ownership. Pena:Nektar Therapeutics: Employment, Equity Ownership. Quach:Nektar Therapeutics: Employment, Equity Ownership. Moffet:Nektar Therapeutics: Employment, Equity Ownership. Nieves:Nektar Therapeutics: Employment, Equity Ownership. Zhang:Nektar Therapeutics: Employment, Equity Ownership. Marcondes:Nektar Therapeutics: Employment, Equity Ownership. Madakamutil:Nektar Therapeutics: Employment, Equity Ownership. Zalevsky:Nektar Therapeutics: Employment, Equity Ownership.

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Development of Molecular Mutations during the Evolution of Therapy-Related MDS and Therapy-Related AML

Blood ◽

10.1182/blood.v124.21.4624.4624 ◽

2014 ◽

Vol 124 (21) ◽

pp. 4624-4624

Author(s):

Wolfgang Kern ◽

Manja Meggendorfer ◽

Tamara Alpermann ◽

Andreia de Albuquerque ◽

Claudia Haferlach ◽

...

Keyword(s):

Bone Marrow ◽

Peripheral Blood ◽

Gene Panel ◽

Employment Equity ◽

Time Points ◽

Number Of Patients ◽

Patients At Risk ◽

Previously Treated ◽

Equity Ownership ◽

Time Point

Abstract Introduction: Therapy-related myelodysplastic syndrome (t-MDS) and acute myeloid leukemia (t-AML) develop after the application of chemotherapy for malignancies in a significant number of patients (pts). Mutations in TP53 have been described recently to be present even before chemotherapy for the prior malignancy and thus also before any sign of t-MDS or t-AML. Data suggested that chemotherapy selected the TP53mutated clone which evolved to t-MDS/t-AML. More comprehensive genetic analyses, however, have been lacking so far. Aim: To identify molecular mutations by a comprehensive gene panel in pts at t-MDS/t-AML diagnosis and to backtrack them to prior time points. Patients and Methods: We searched our database for pts diagnosed with t-MDS or t-AML for whom in addition ≥1 prior peripheral blood or bone marrow sample from assessment of a previously treated malignancy was stored. Diagnosis of t-MDS and t-AML was performed by cytomorphology, cytochemistry and cytogenetics according to WHO classification 2008 in all cases. A total of 11 pts were identified (3/8 females/males; median age at t-MDS/t-AML diagnosis 72 years, range 50-81 years). 8 pts had t-MDS and 3 had t-AML. All pts had received chemotherapy for CLL before. All pts underwent mutation analysis at t-MDS/t-AML diagnosis by a 26 gene panel targeting ASXL1, BCOR, BRAF, CBL, DNMT3A, ETV6, EZH2, FLT3-TKD, GATA1, GATA2, IDH1, IDH2, JAK2, KIT, KRAS, MPL, NPM1, NRAS, PHF6, RUNX1, SF3B1, SRSF2, TET2, TP53, U2AF1, and WT1. The library was generated with the ThunderStorm (RainDance Technologies, Billerica, MA) and sequenced on MiSeq instruments (Illumina, San Diego, CA). Specific mutations identified at t-MDS/t-AML diagnosis were selectively analyzed in prior samples of the respective patients. Mutations were considered for this analysis only if they were present at t-MDS/t-AML diagnosis at mutation loads clearly higher than residual CLL infiltration. Accordingly, mutations were excluded from this analysis if their load was in the range of residual CLL infiltration or lower. One not yet described genetic variant was also excluded. Results: 13 mutations were identified at t-MDS/t-AML diagnosis in 8/11 pts. While in 3 pts no mutations were found, 5 pts had 1 mutation, 2 had 2, and 1 had 4 mutations. Mean number of mutations per pt was 1.6. TP53 was mutated most frequently (n=5), RUNX1 was mutated in 2 pts, and FLT3-TKD, IDH2, KRAS, NPM1, NRAS, and U2AF1 in 1 pt each. Mean mutation load was 27% (range 4-48%) while mean CLL infiltration at the same time point was 2% (range 0-4%). Thus, the attribution of the described mutations to t-MDS/t-AML is highly likely. We then analyzed a total of 13 samples (8 bone marrow, 5 peripheral blood) drawn prior to t-MDS/t-AML diagnosis from the 8 pts for the respective mutations identified at t-MDS/t-AML diagnosis. In 5/8 patients the respective specific mutations identified at t-MDS/t-AML diagnosis were found in at least one prior sample. Genes found mutated in the prior samples were TP53 in 2 cases and IDH2, KRAS, NPM1, RUNX1, and U2AF1 in 1 case each. Mutation loads in general were lower in prior samples as compared to samples at t-MDS/t-AML diagnosis (median 54-fold lower, range 1.5 to 205-fold), except for one sample with a similar load at both time points which both times was clearly higher than the residual CLL infiltration (50% and 42% vs. 9% and 4%). Specifically, in 3/4 patients with samples available from the time point of CLL diagnosis all of these mutations (n=4) were not detectable at a sensitivity level of 1% while in 1 patient 2 mutations were not detectable and a U2AF1mutation was identified with a 1.9% load. This further supports the concept of these mutations being related to a pre-malignant clone which in the majority of cases might have been present at undetectable levels at the time point of CLL diagnosis or which even developed only during chemotherapy and later evolved into t-MDS/t-AML. The mean interval from first detection of the respective mutations to t-MDS/t-AML diagnosis was 10 months (range 4-25 months). Conclusions: Mutational screening applying a 26 gene panel identified molecular mutations in the majority of pts. These mutations were present up to 2 years before t-MDS/t-AML diagnosis. Further studies focusing on patients at risk of t-MDS/t-AML should clarify the role of early molecular screening helping to potentially improve diagnosis and management of t-MDS/t-AML. Disclosures Kern: MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Meggendorfer:MLL Munich Leukemia Laboratory: Employment. Alpermann:MLL Munich Leukemia Laboratory: Employment. de Albuquerque:MLL Munich Leukemia Laboratory: Employment. Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Schnittger:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership.

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Modeling Targeted Lymphodepletion with Radiolabeled CD45 Antibody As a Promising Preparative Regimen Prior to Adoptive Cell Therapy or CAR-T

Blood ◽

10.1182/blood-2018-99-119740 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 5682-5682

Author(s):

Dale L Ludwig ◽

Mark S. Berger ◽

Dadachova Ekaterina ◽

Kevin Allen ◽

Wojciech Dawicki

Keyword(s):

Bone Marrow ◽

T Cells ◽

Cell Therapy ◽

Research Funding ◽

Adoptive Cell Transfer ◽

Cell Transfer ◽

Immune Microenvironment ◽

Employment Equity ◽

Car T ◽

Equity Ownership

Abstract Prior to a patient receiving a dose of an adoptive cell transfer such as engineered autologous or allogeneic CAR-T cells, it is common to perform a lymphodepletion step often using high dose chemotherapy. This process is considered important to create sufficient space in the immune microenvironment, e.g. bone marrow, to allow the transferred cells to engraft. Further, it appears to elicit a favorable cytokine profile for establishment and proliferation of the donor lymphocytes. Anti-CD45 radioimmunotherapy (RIT) is being investigated in a Phase III clinical trial as a myeloablative targeted conditioning regimen prior to allogeneic hematopoietic cell transplantation in AML patients. In this study, a low 131I-CD45 RIT dosimetric dose is administered to each patient and imaging performed to define a personalized therapeutic dose. Results from studies performed post-dosimetric dose demonstrate that lower doses of 131I-anti-CD45 RIT may be suitable for use as a preparative conditioning or lymphodepleting regimen prior to cell therapy such as CAR-T. Significantly, targeted conditioning with pan-CD45 antibody, which selectively targets all nucleated immune cells, is anticipated to deplete not only lymphocytes, but also macrophages, as well as immune suppressive regulatory T cells (T-regs) and myeloid-derived suppressor cells in the immune microenvironment. It may also exert a direct anti-tumor effect on CD45+ hematopoietic cancers. We hypothesized that targeted lymphodepletion may result in a more suitable immune homeostatic environment for the reception of adoptive cell therapies, and possibly reduce the incidence of cytokine release syndrome. We have performed preclinical studies using a 131I- labeled surrogate anti-mouse pan-CD45 antibody (30F11) to investigate in a mouse model the response of targeted RIT lymphodepletion on particular immune cell types and resulting changes in immune cytokine expression. Following single dose administration of non-myeloablative doses of CD45-RIT, peripheral blood, bone marrow and spleen samples were collected from 8-12 week C57Bl/6 mice at 48 and 96 hours post-treatment for immunophenotyping to evaluate lymphoid and myeloid subsets for lymphodepletion, and serum for cytokine profiling. CD45-RIT was shown to effect a considerable reduction in both lymphocyte and myeloid cell counts, inclusive of immune suppressive T regs and MDSCs. Further, the cytoreduction by CD45-RIT was shown to induce the expression of immune homeostatic cytokines including IL-15. Studies are in progress to evaluate CD45-RIT as a targeted lymphodepletion regimen in E.G7 lymphoma tumor bearing mice prior to adoptive cell transfer with OVA-specific CD8+ T cells. Disclosures Ludwig: Actinium Pharmaceuticals: Employment, Equity Ownership. Berger:Actinium Pharmaceuticals: Employment, Equity Ownership. Ekaterina:Actinium Pharmaceuticals: Consultancy, Research Funding; Radimmune Therapeutics: Consultancy, Research Funding.

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5-Azacytidine Induces NOXA and PUMA Expression to Prime AML Cells for Venetoclax-Mediated Apoptosis

Blood ◽

10.1182/blood-2018-99-111985 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 2644-2644

Author(s):

Dan Cojocari ◽

Sha Jin ◽

Julie J Purkal ◽

Relja Popovic ◽

Nari N Talaty ◽

...

Keyword(s):

Clinical Trial ◽

Cell Lines ◽

Acute Treatment ◽

Low Dose ◽

Dna Demethylation ◽

Phase Iii ◽

Employment Equity ◽

Phase Iii Clinical Trial ◽

Equity Ownership

Abstract Acute myeloid leukemia (AML) is a clonal hematologic malignancy characterized by genomic heterogeneity and epigenetic changes, including aberrant DNA hypermethylation. Phase-Ib clinical data in relapsed/refractory AML patients indicate that combining venetoclax with the hypomethylating agents (HMAs) 5-azacitidine (5-Aza) or decitabine results in an overall response (OR) of 62% (DiNardo et al. 2018) compared to the historical OR of 28-29% with HMAs treatment alone (Kantarjian et al. 2013; Dombret et al. 2015). Subsequently, a randomized phase-III clinical trial was initiated to evaluate venetoclax activity in combination with 5-Aza in treatment-naïve AML patients ineligible for standard induction therapy (M15-656, NCT02993523). However, the underlying mechanism for the combinational activity observed between venetoclax and 5-Aza is unknown. In this study, we demonstrate that both chronic low-dose 5-Aza treatment, which induced global DNA demethylation, and acute treatment (24 hours, non-epigenetic effects) can drive combinational activity with venetoclax in AML through distinct mechanisms. Chronic culture with a low-dose 5-Aza for one week sensitized AML cell lines to venetoclax in vitro. In contrast, acute treatment with 5-Aza, activated the integrated stress response (ISR) pathway to induce expression of the BH3-only proteins NOXA (PMAIP1) and PUMA (BBC3) in human AML cell lines, independent of DNA methylation. This resulted in an increase in the amount of NOXA and/or PUMA in complex with anti-apoptotic proteins like BCL-2, BCL-XL and MCL-1, thereby "priming" AML cells for induction of apoptosis by venetoclax treatment. Priming for apoptosis resulted in significant synergistic cell death in a panel of AML cell lines treated with venetoclax and 5-Aza in vitro. In this panel of cell lines, the level of the PMAIP1, BBC3, and DDIT3 gene induction correlated with the synergy observed between venetoclax and 5-Aza. Importantly, subsequent PMAIP1 deletion significantly impacted the kinetics and depth of apoptosis induced by 5-Aza or venetoclax alone or in combination. In accordance with the in vitro combinational activity, the venetoclax/5-Aza combination provided added benefit over either agent alone in two xenograft models of AML. Together, these data provide a rationale for an ongoing randomized phase-III clinical trial evaluating venetoclax activity in combination with 5-Aza (M15-656, NCT02993523). Disclosures: DC, SJ, JP, RP, NT, YX, EB, JL, and DP are employees of AbbVie. LS is a former employee of AbbVie and was employed during the duration of this study. The design, study conduct, and financial support for this research were provided by AbbVie and Genentech. AbbVie participated in the interpretation of data, review, and approval of the publication. Disclosures Cojocari: AbbVie Inc: Employment. Jin:AbbVie Inc: Employment, Equity Ownership. Purkal:AbbVie Inc: Employment, Equity Ownership. Popovic:AbbVie Inc: Employment, Equity Ownership. Talaty:AbbVie Inc: Employment, Equity Ownership. Xiao:AbbVie Inc: Employment, Equity Ownership. Solomon:AbbVie Inc: Equity Ownership. Boghaert:AbbVie Inc: Employment, Equity Ownership. Leverson:AbbVie Inc: Employment, Equity Ownership, Patents & Royalties. Phillips:AbbVie Inc: Employment, Equity Ownership, Patents & Royalties.

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