ALBERT

Description: Background:Harnessing the cytotoxic properties of T cells to destroy tumor cells has been the central goal of anti-cancer immunotherapy. One approach to achieve this goal has been the use adoptive cell transfer (ACT). This method involves the isolation, in vitro manipulation and re-infusion of antigen-specific T cells into cancer patients. This approach has been used to mediate durable responses in a number of malignancies. Despite its significant therapeutic potential, the routine use of ACT has been limited. This has been due, in large part, to the high cost, intricate and labor-intensive methods required to successfully generate autologous antigen-specific T cells. There is a clear need for less expensive more efficient and streamlined approaches for generation of antigen-specific T cells for use in ACT. To this end, we have developed a T cell Enrichment+Expansion strategy using paramagnetic, Nano scale artificial Antigen Presenting Cells (nano-aAPCs), which are capable of enriching rare tumor-specific T cells in a magnetic column and activating them. Nano-aAPCs, are not only more biocompatible than traditional aAPC, but by manipulating paramagnetic nanoparticle based aAPC with magnetic fields, we propose a method to quickly generate large numbers of high frequency tumor-specific T cells. Our hypothesis is that magnetic enrichment and expansion with nano-aAPC can reduce time in culture and increase frequency of antigen-specific cells, two factors that we predict will improve T cell expansion and persistence after adoptive transfer. Methods:HLA-Ig dimer was loaded with tumor antigen peptides for MART1, NY-ESO and WT1. To manufacture nano-APCs, magnetic nanoparticles (size 50-100nm) were decorated with loaded HLA-Ig (signal 1) and anti-CD28 antibody (signal 2). Peripheral blood mononuclear cells (PBMCs) were collected from normal donors and CD8+ T cells were isolated. CD8+ T cells were subsequently incubated with nano-APCs. The T cell/nano-APCs mixtures were then pass through a magnetic column. The relevant T cells were bound to the nano-APCs and therefore were attached to the column while the irrelevant T cells passed through the column. Relevant T cells were then washed off the column and cultured using standard T cell culture techniques for 7 days. Cell number and specificity were evaluated on Day 0 and day 7. Results: CD8+ T cells specific for the tumor antigens MART1, NYESO and WT1 were successfully expanded using our nano-APCs. After one week, we saw fold expansions of 〉100-fold for all 3 antigens studied. T cell specificity increased from

Description: Several cell-based immunotherapy strategies have been developed to specifically modulate T cell–mediated immune responses. These methods frequently rely on the utilization of tolerogenic cell–based antigen-presenting cells (APCs). However, APCs are highly sensitive to cytotoxic T-cell responses, thus limiting their therapeutic capacity. Here, we describe a novel bead-based approach to modulate T-cell responses in an antigen-specific fashion. We have generated killer artificial APCs (κaAPCs) by coupling an apoptosis-inducing α-Fas (CD95) IgM mAb together with HLA-A2 Ig molecules onto beads. These κaAPCs deplete targeted antigen-specific T cells in a Fas/Fas ligand (FasL)–dependent fashion. T-cell depletion in cocultures is rapidly initiated (30 minutes), dependent on the amount of κaAPCs and independent of activation-induced cell death (AICD). κaAPCs represent a novel technology that can control T cell–mediated immune responses, and therefore has potential for use in treatment of autoimmune diseases and allograft rejection.

Description: Immunotherapy is the modulation of a patient’s immune system to treat illness. Unfortunately many T cell based attempts have failed due to the fact that existing tumor-specific T cells are mostly anergic or tolerized and ex vivo generated T cells are often already of exhausted phenotype. Therefore, investigators have developed alternative approaches including bispecific antibody technology to redirect fully functional non-tumor specific T cells to the tumor. This has been primarily accomplished through targeting CD3 which is expressed on all T cells to engage and redirect them towards a molecule that is expressed on the tumor cells. Here we present a novel nanoparticle based approach to selectively target cytotoxic T cells (CTL) and re-direct them to kill tumors, termed ATR (Antigen-specific T cell Redirectors). ATR were generated by coupling either MHC-Ig dimer or clonotypic anti-TCR antibody 1B2 to target the effector T cell population and an anti-CD19 to re-direct those to CD19+ tumor target cells onto 50-100nm nanoparticles. Flow cytometry and microscope based data confirm that the described ATR phenotype efficiently and stably stain tumor and T cells in a dose dependent manner and ATR mediate antigen-specific conjugate formation of effector T cells and tumor target cells. We further developed two clinically relevant protocols to test and optimize our ATR in vitro. First a pre-treatment approach in which the effector T cells are pre-incubated with ATR mimicking an adoptive transfer approach and second a co-culture protocol that mimics an active immunotherapy approach of direct ATR injection. Antigen-specific ATR mediated re-direction of T cells to tumor target cells was demonstrated in 51Cr-release killing assays at low E:T ratios. Variation of ATR target-cell : effector-cell targeting molecule ratio could further increase efficacy. Finally, intra tumoral ATR injection induced T cell re-direction and reduced tumor growth in a s.c. Raji/SCIDbeige treatment model. In summary this data demonstrates that ATR target and redirect antigen-specific CTL to tumor cells that would otherwise not be recognized and mediates their lysis. ATR can be used to develop new innovative immunotherapeutic approaches for all cancers that can be targeted with antibodies or antibody-like molecules. Furthermore, ATR could also be used in conjunction with virus-specific immunization to specifically increase the targeted CTL population. Ultimately, we expect ATR and their potential for clinical applications to increase our understanding of tumor immunotherapy through T cell redirection. Disclosures Oelke: NextImmune: Equity Ownership. Schneck:NextImmune: Equity Ownership.

Description: The clinical application of T-cells for adoptive immunotherapy often requires the ex vivo stimulation and expansion of antigen-specific T cells and the re-transfer of the expanded T cells into patients. One strategy to generate such T-cell products includes the use of autologous antigen-presenting cells (APCs) which vary essentially in quality and quantity. Furthermore, other strategies for the generation of APCs such as dendritic cells (DCs) are labor intensive and expensive. To circumvent these disadvantages, many investigators have focussed their research on the development of artificial APCs (aAPCs). Recent studies have demonstrated that microbeads loaded with MHC-peptide molecules in monomeric or Ig-coupled dimeric forms and co-stimulatory antibodies such as anti-CD28 and anti-4-1BB are reproducibly capable to induce high numbers of antigen-specific T-cells. In our study, we wanted to address the question if the use of further stimulatory signals in addition to CD28/4-1BB could induce higher stimulatory capacities in aAPCs. We loaded epoxy surface activated magnetic beads (DynaBeads Epoxy M-450) with HLA-B*0702/CMV_pp65 (TPRVTGGGAM) monomer and activating antibodies (AB) and/or ligands (L) against co-stimulatory molecules of the CD28 and/or the TNF-receptor (TNFR) family: namely CD28 (AB), ICOS (AB), 4-1BB (AB+L), CD27 (L), OX40 (L). The molar ratio between MHC and the co-stimulatory molecules was between 1:1 and 1:5 with a total amount of MHC-molecules of approximately 2×105 molecules/aAPC. Cell cultures were maintained as described previously 1 and analyzed weekly by staining with HLA-B*0702/CMV_pp65 (TPRVTGGGAM) tetramers and surface antibodies against the surface markers CD3, CD8, CD45RA, CCR7, CD57 and CD25. Our results demonstrate that CD28 triggering is pivotal on aAPCs besides the antigen-specific signal for an optimal expansion of CMV-specific CTL. This signal can not be replaced by ICOS or 4-1BB either alone or in combination. The addition of ICOS and/or 4-1BB to CD28 did not significantly improve the percentage of specific T-cells after 3 weeks of culture although a trend to higher cell numbers and higher specificity when combining CD28, ICOS (AB) and 4-1BB (AB) was observed. Here, longer time periods may be required to evaluate the capacity of this combination to maintain long term cultures of antigen-specific CTL. Therefore, we always applied HLA-B*0702/CMV_pp65 monomer and CD28 (AB) on the aAPCs in further experiments and supplemented these molecules by the other co-stimulatory signals as described above. Our data suggests that the phenotype (and thereby potential effector functions/in vivo survival) varies when triggering different costimulatory pathways via aAPCs. Interestingly, we could detect a higher amount of central memory T-cells (CCR7+/CD45RA−) in samples co-stimulated with the 4-1BB antibody, compared to samples treated with other co-stimulations [e.g. MHC/CD28: 6.2 % of CD8+/Tet+ vs. MHC/CD28/4-1BB (AB): 23.5 % of CD8+/Tet+]. Another difference was seen in OX40 ligand co-stimulated samples when analyzing CD57 and CD25 expression: Here, CD8+/tetramer+ T-cells had a higher content of non-activated (CD25−) T-cells with less replicative history (CD57−) than samples co-stimulated with other co-stimulations [e.g. MHC/CD28: 23 % of CD8+/Tet+ vs. MHC/CD28/OX40 (L): 45.2 % of CD8+/Tet+]. These preliminary findings suggest that the CD28 signal on aAPCs is indispensable for expansion of CMV-specific T-cells. But the phenotype and thereby in vivo functionality may be controlled by the use of defined other co-stimulatory signals like members of the CD28 and/or TNFR family. Further tests will have to define optimal amounts of MHC-molecules on aAPCs and their ratio to co-stimulatory molecules.

Description: Relapse after allo-HSCT is the leading cause of death in patients with AML. While donor lymphocyte infusions (DLI) achieve modest graft-versus-leukemia (GVL) effects in a small group of responders, responses are often accompanied by significant morbidity and mortality from graft-versus host disease (GVHD). Therefore, there is a significant need for cellular approaches that enhance the benefit of GVL while decoupling toxicities associated with GVHD. Herein, we report initial results from a first-in-human study of a non-genetically engineered adoptive cellular therapy product, NEXI-001, which contains populations of anti-leukemia antigen-specific CD8+ T cells. NEXI-001is generated using a novel technology platform referred to as Artificial Immune Modulation (AIM). Specifically, nano-artificial Antigen Presenting Cells are used in combination with a proprietary cellular expansion system to isolate and expand populations of CD8+ T cells that recognize five specific HLA 02.01-restricted peptides from the WT1, PRAME, and Cyclin A1 antigens, each of which is commonly over-expressed on AML blasts and leukemic stem cells. The ability to direct T cells against multiple leukemic antigens may reduce potential for tumor escape via target down-regulation. The AIM manufacturing process is optimized to consistently produce cellular products that contain T cell subtypes which combine anti-tumor potency with long-term persistence. Each NEXI-001 product is comprised of 〉95% memory T cells, and include stem-like central memory (Tscm), central memory (Tcm) and effector memory (Tem) cells - those T cell subtypes with potential to provide long lasting GVL effects. Importantly, each product also contains very low proportions of naïve T cells with allo-reactive potential (Tn), which may further reduce the risk of GVHD. (Table 1) Patients underwent bridging therapy to control leukemic burden while NEXI-001 T cells were manufactured for 14 days. After a 14-day wash out period, lymphodepleting therapy (fludarabine 30mg/m2, Cytoxan 300mg/m2 D-5 to D-3) was given followed by two rest days before NEXI-001 cell infusion. Dose levels for Phase 1 patients enrolled include safety D-1 (50 million T cells, n=1); followed by two additional dose-escalating safety cohorts {100 million T cells (n=3); and 200 million T cells, (n=3)}, and expansion cohort (n=16). A total of 7 AML patients (median age 43) with HLA-02:01 who had relapsed after allo-HSCT have been enrolled to-date. The same HLA-matched donor PBMCs are used for NEXI-001 manufacturing. Median time from previous SCT to relapse was 10 months, median bone marrow blast at relapse was 9%. and all patients were determined as poor risk category. To-date, there have been no infusion reactions, CRS or ICANS events observed for any patient treated. Significantly, there is no evidence of GVHD in any patient (n=3). Analysis of primary end point demonstrates a safe and well tolerated profile. Analyses of secondary end points support early signs of clinical response. We observed early and significant in vivo T cell proliferation as early as Day 5 (Figure 1). This may suggest that NEXI- T cells are actively engaging leukemic targets. Multimer staining confirmed the presence of NEXI-001 T cells in peripheral blood (Figure 2). Uniquely, the CD8+ T cells in peripheral blood maintain the phenotype subsets of the infused product over all time points measured (Figure 3). Despite complete lymphodepletion, CD4 reconstitution is robust, earlier than expected and consistent with increased levels of IL2. Evidence of cytotoxic activity, likely mediated by CD8+ T cells, was evident with increased serum levels of IFNg, TNFa, Granzymes A and B, and sFas. Additionally, we observed recruitment and trafficking of CD4 T cells to the bone marrow which may contribute to the initiation of a more robust cell-mediated immune response. Maintaining populations of T-stem cell and T-central memory subtypes may provide marrow-resident effector T cells with a source of continued replenishment over time, providing potential for a durable anti-tumor response. In conclusion, early results suggest that infusion of NEXI-001 product, is safe, well tolerated and capable of generating an early and robust cell-mediated immune response in patients with relapsed AML post allo-HSCT. As a novel cellular therapy, NEXI-001 may have potential to enhance the benefit of GVL while decoupling the toxicities associated with GVHD. Disclosures Al Malki: Neximmune: Consultancy; Jazz Pharmacuticals, Inc: Consultancy; Rigel Pharma: Consultancy. Perales:Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Kite/Gilead: Honoraria, Research Funding; Miltenyi Biotec: Research Funding; Medigene: Membership on an entity's Board of Directors or advisory committees, Other; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Nektar Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Merck: Consultancy, Honoraria; Servier: Membership on an entity's Board of Directors or advisory committees, Other; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria; Incyte Corporation: Honoraria, Research Funding; MolMed: Membership on an entity's Board of Directors or advisory committees; Omeros: Honoraria, Membership on an entity's Board of Directors or advisory committees; NexImmune: Membership on an entity's Board of Directors or advisory committees; Cidara Therapeutics: Other; Bellicum: Honoraria, Membership on an entity's Board of Directors or advisory committees. Modi:MorphoSys: Membership on an entity's Board of Directors or advisory committees. Vasu:Janssen: Membership on an entity's Board of Directors or advisory committees; Kiadis Inc: Other: Kiadis has obtained exclusive licensing requirements from The OHio State University; Omeros: Membership on an entity's Board of Directors or advisory committees. Kim:Neximmune: Current Employment. Wang:Neximmune: Current Employment. Lu:Neximmune: Current Employment. Oelke:Neximmune: Current Employment. Myint:Neximmune: Current Employment, Current equity holder in private company; BMS: Current equity holder in publicly-traded company; Celgene: Ended employment in the past 24 months. Varela:Neximmune: Consultancy, Current equity holder in private company.