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Development of chimeric antigen receptor T cell (CART) therapy has led to an unprecedented success against B-cell leukemia and lymphoma and resulted in U.S. Food and Drug Administration-approved treatment protocols. Despite the initial clinical response in B cell-related malignancies, high relapse rates suggest that much work is needed to uncover mechanisms of resistance. In chronic lymphocytic leukemia (CLL), the durable activity of CAR T-cells is limited, and CAR T-cell therapy success is lower than in other malignancies. T cells from these patients are vulnerable to a state of dysfunction because of stresses including chronic infection, rapid cell cycle on antigen recognition, immunosuppressive tumor microenvironment, and cancer-related treatments. T cells are also introduced to additional stresses when cultured ex vivo during the CAR T-cell manufacturing process. All these factors contribute to the limited regenerative capacity of T cells, which can lead to CAR T-cell treatment failure. In this article, we review the challenges of CAR T-cell therapy in patients with CLL and discuss potential strategies to overcome these challenges.

With the development of various strategies of anti-CD19 immunotherapy for treatment of B cell malignancies, it remains to be elucidated whether CD19 targeting with a monoclonal antibody impairs subsequent CD19 targeted chimeric antigen receptor T cell (CART19) therapy. In this study, we evaluated the potential interference between the CD19 targeting monoclonal antibody tafasitamab and CART19 treatment (using a construct similar to the FDA approved therapy, FMC63-41BBζ, tisagenlecleucel) in preclinical lymphoma and leukemia models. For in vitro assays, the CD19 + cell lines JeKo-1 (mantle cell lymphoma), Nalm6 (acute lymphoblastic leukemia), and OCI-Ly7 (diffuse large B cell lymphoma) were used. When CART19 were co-cultured with CD19 + tumor cells in the presence of increasing concentrations of tafasitamab (10-400 µg/mL) or the isotype control, an impairment of CART19 functions at the highest concentration of tafasitamab was observed. However, when tafasitamab was cocultured with tumor cells overnight and removed from the culture by washing, there was no impairment of CART19 anti-tumor activity or effector functions compared to a pre-culture with isotype control. We then aimed to validate these findings in xenograft mouse models by determining whether prior tafasitamab treatment impairs subsequent CART cell function. First, a two-step JeKo-1 xenograft model was created through inoculation of 1x10 6 luciferase + JeKo-1 cells to immunocompromised NOD-SCID-γ -/- (NSG) mice via tail vein injection. One week later, tumor burden was assessed by bioluminescence imaging (BLI) and mice were randomized to receive either 1) PBS (Group 1) or 2) 10 mg/kg of tafasitamab (Group 2) (Fig. 1A). Treatment was performed until the mice reached the endpoint due to the high tumor load. When reaching the endpoint, mice were euthanized and spleen was harvested. Splenic cells were then injected to naïve NSG mice. Two weeks after the inoculation of splenic cells (PBS or tafasitamab treated), mice were imaged with BLI and randomized according to their tumor burden to receive 2x10 6 of 1) untransduced T cells (UTD) or 2) CART19 (i.v.) (Fig. 1B). Mice, treated with CART19 demonstrated potent anti-tumor effects and showed prolonged survival compared to UTD control mice. Interestingly, CART19-treated mice inoculated with Group 2 splenic cells (pretreated with tafasitamab) showed a significantly better tumor control and overall survival compared with mice engrafted Group 1 splenic cells (PBS pretreatment) (Fig. 1C). This finding led us to further investigate the effects of prior tafasitamab therapy on subsequent CART19 treatment. In this context, we studied the sequential treatment with tafasitamab and CART19 in an additional JeKo-1 xenograft model (Fig. 1D). In brief, NSG mice were inoculated with luciferase + JeKo-1 on day -14. On day -8, mice were imaged and randomized to the PBS (Group I) or tafasitamab (10 mg/kg) group. On day -1 tafasitamab treated mice were imaged again, randomized to the tafasitamab discontinuation (Group II) or continuation (Group III). Treatment with PBS was continued in Group I. All groups were administered with 1x10 6 of CART19 on day 0. Cotreatment of JeKo-1 xenografts with tafasitamab and CART19 led to impaired anti-tumor activity presumably as a result of CD19 binding competition between tafasitamab and CART19 (Group III). Mice treated with tafasitamab followed by CART19 had improved tumor control compared to mice treated with PBS followed by CART19 (Fig. 1E-F). Serial peripheral blood analysis demonstrated that mice from Group I showed the highest CART19 expansion on day 10. Strikingly, Group II exhibited weak CART19 expansion at day 10, but strongest expansion on day 23 (Fig. 1G). We therefore hypothesized that prior treatment with tafasitamab results in modulation of CART19 cell activation. To test this hypothesis, spleens of satellite mice were harvested 24 hours after CART19 administration. Flow cytometric analysis revealed that the mice from Group II showed significantly lower CD69 and HLA-DR expression on CART19 cells compared with Group I, and reduced apoptosis as measured by the Annexin assay (Fig. 1H-I). In summary, concomitant treatment of tafasitamab and CART19 led to impaired anti-tumor activity while, in contrast, sequential treatment of tafasitamab and CART19 did not inhibit CART19 anti-tumor activity but rather promoted anti-tumor effects in xenograft models. Figure 1 Figure 1. Disclosures Sakemura: Humanigen: Patents & Royalties. Augsberger: MorphoSys AG: Current Employment. Schanzer: MorphoSys AG: Current Employment. Patra-Kneuer: MorphoSys AG: Current Employment. Heitmüller: MorphoSys AG: Current Employment. Steidl: MorphoSys AG: Current Employment. Endell: MorphoSys AG: Current Employment. Ding: DTRM: Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; Octapharma: Membership on an entity's Board of Directors or advisory committees. Parikh: Pharmacyclics, MorphoSys, Janssen, AstraZeneca, TG Therapeutics, Bristol Myers Squibb, Merck, AbbVie, and Ascentage Pharma: Research Funding; Pharmacyclics, AstraZeneca, Genentech, Gilead, GlaxoSmithKline, Verastem Oncology, and AbbVie: Membership on an entity's Board of Directors or advisory committees. Kay: Acerta Pharma: Research Funding; Targeted Oncology: Membership on an entity's Board of Directors or advisory committees; Oncotracker: Membership on an entity's Board of Directors or advisory committees; Juno Therapeutics: Membership on an entity's Board of Directors or advisory committees; Morpho-sys: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Dava Oncology: Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Research Funding; Behring: Membership on an entity's Board of Directors or advisory committees; CytomX Therapeutics: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Rigel: Membership on an entity's Board of Directors or advisory committees; MEI Pharma: Research Funding; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol Meyer Squib: Membership on an entity's Board of Directors or advisory committees, Research Funding; Tolero Pharmaceuticals: Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees; Agios Pharm: Membership on an entity's Board of Directors or advisory committees; Genentech: Research Funding; Sunesis: Research Funding. Nowakowski: Celgene, NanoString Technologies, MorphoSys: Research Funding; Celgene, MorphoSys, Genentech, Selvita, Debiopharm Group, Kite/Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees. Cox: Humanigen: Patents & Royalties. Kenderian: Humanigen, Inc.: Consultancy, Honoraria, Research Funding.

Owing to the difficulty in isolating T cells from human biopsy samples, the characteristics of T cells that are infiltratinghuman acute graft-versus-host disease (GVHD) tissues remain largely uninvestigated. In the present study, TCR-β deep sequencing of various GVHD tissue samples and concurrent peripheral blood obtained from transplant recipients was performed in combination with functional assays of tissue-infiltrating T cell clones. The T cell repertoire was more skewed in GVHD tissues than in the peripheral blood. The frequent clonotypes differed from tissue to tissue in the same patient, and the frequent clonotypes in the same tissue differed from patient to patient. Two T cell clones were successfully isolated from GVHD skin of a patient. In a cytotoxicity assay, both Tcell clones lysed patient peripheral blood mononuclear cells, but not donor-derived Epstein-Barr virus-transformed lymphoblastoid cells. Their clonotypes were identical to the most and second most frequent T cell clonotypes in the original GVHD skin and accounted for almost all of the skin-infiltrating T cells. These results suggest that human acute GVHD may result from only a few different alloreactive cytotoxic T cell clones, which differ from tissue to tissue and from patient to patient. The characterization of T cells infiltrating human GVHD tissues should be further investigated.

CD19-targeted chimeric antigen receptor T cell (CART19) therapy has been remarkably successful in treating a subset of patients with hematological malignancies. However, it is associated with significant toxicities, including cytokine release syndrome (CRS) and neurotoxicity (NT). Furthermore, the rate of durable responses after CART19 therapy is low, and most patients develop resistance to the therapy. One of the predominant mechanisms for CART cell resistance is intrinsic T cell dysfunction which leads to a suboptimal CART product. The Bruton's tyrosine kinase (BTK) inhibitor ibrutinib has been shown to favorably modulate CART phenotype and function through downregulation of inhibitory receptors and enhancement of CART cell efficacy in preclinical models and early clinical studies. However, ibrutinib is an irreversible receptor tyrosine kinase (RTK) inhibitor, and thus there are concerns that it inhibits CART cell proliferation and expansion. In contrast to ibrutinib and other BTK inhibitors, vecabrutinib has recently emerged as a potent, reversible, non-covalent BTK inhibitor that can block the activity of both wild type and C481 mutant BTK as well as interleukin-2-inducible T-cell kinase (ITK). We hypothesized that treatment with vecabrutinib improves CART19 antitumor efficacy through the reversible inhibition of BTK/ITK, independent of its antitumor effect. To test this hypothesis, we assessed whether vecabrutinib potentiates CART19 cytotoxicity against CD19 + tumor cells. Killing of the CD19 + mantle cell lymphoma cell line, JeKo-1, was significantly increased when CART19 were combined with vecabrutinib (Fig. 1A). Of note, vecabrutinib did not induce antitumor activity in this model as a single agent (Fig. 1A). In addition, vecabrutinib (10 µM) treatment of CART19 resulted in enhanced antigen-specific proliferation (Fig. 1B). Next, we aimed to study the direct impact of vecabrutinib on CART19 cytokine production. We measured the levels of multiple pro-inflammatory cytokines in the supernatant of CART19 co-cultured for 3 days with JeKo-1 cells and vecabrutinib. Vecabrutinib did not impair CART19 degranulation, as measured by flow cytometric assessment of CD107a expression (Fig. 1C). Cytokines known to play a crucial part in the development of CRS, such as IL-6, IL-10, and MIP-1β were significantly downregulated in cocultures with vecabrutinib (Fig. 1D-F). We then investigated whether the addition of vecabrutinib to CART19 caused a synergistic antitumor effect in vivo. We used our established JeKo-1 lymphoma xenograft models. Here NSG mice were engrafted with CD19 + luciferase + JeKo-1 cells. Mice were then imaged for engraftment and randomized to treatment with 1) untransduced control T cells, 2) CART19 with vehicle, or 3) CART19 with vecabrutinib 50 mg/kg BID administered via oral gavage over a period of 4 weeks. Vecabrutinib combination with CART19 treatment led to sustained antitumor activity (Fig.1G) and increased CART19 proliferation (Fig.1H). Encouragingly, mice treated with vecabrutinib better maintained their body weight following CART19 infusion, suggesting possibly dampened toxicity (Fig.1I). We also measured serum cytokine levels from patients on a phase 1 clinical trial (NCT03037645) testing vecabrutinib in B cell malignancies at baseline and four weeks after treatment. We found that vecabrutinib significantly reduces the levels of multiple pro-inflammatory cytokines linked to CART cell toxicity, including MIP-1β, IP-10, and TNF-a (Fig. 1J-L), further validating our preclinical findings. Finally, we interrogated the transcriptome of CART19 co-cultured with JeKo-1 with or without vecabrutinib. Total RNA sequencing of activated CART19 highlighted a significant enhanced expression of multiple genes involved in the PI3K/AKT and Th1 pathways compared to antigen stimulated CART19 alone (Fig.1M, N). These results could explain the enhanced proliferation and cytotoxicity induced by vecabrutinib. In summary, we demonstrate for the first time that using the reversible BTK inhibitor, vecabrutinib, is a potent and a novel strategy to favorably modulate CART19 function by increasing their efficacy and decreasing toxicity. Further studies are currently underway to compare the effect of reversible versus irreversible BTK/ITK inhibition on CART functions and to further validate the mechanisms responsible for the observed effects. Figure 1 Figure 1. Disclosures Sakemura: Humanigen: Patents & Royalties. Cox: Humanigen: Patents & Royalties. Fox: Sunesis Pharmaceuticals: Current Employment. Ding: Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; Octapharma: Membership on an entity's Board of Directors or advisory committees; DTRM: Research Funding. Parikh: Pharmacyclics, MorphoSys, Janssen, AstraZeneca, TG Therapeutics, Bristol Myers Squibb, Merck, AbbVie, and Ascentage Pharma: Research Funding; Pharmacyclics, AstraZeneca, Genentech, Gilead, GlaxoSmithKline, Verastem Oncology, and AbbVie: Membership on an entity's Board of Directors or advisory committees. Kay: MEI Pharma: Research Funding; Sunesis: Research Funding; Rigel: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; CytomX Therapeutics: Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Research Funding; Juno Therapeutics: Membership on an entity's Board of Directors or advisory committees; Bristol Meyer Squib: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Behring: Membership on an entity's Board of Directors or advisory committees; Genentech: Research Funding; Morpho-sys: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Targeted Oncology: Membership on an entity's Board of Directors or advisory committees; Tolero Pharmaceuticals: Research Funding; Dava Oncology: Membership on an entity's Board of Directors or advisory committees; Acerta Pharma: Research Funding; Agios Pharm: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Oncotracker: Membership on an entity's Board of Directors or advisory committees. Kenderian: Humanigen, Inc.: Consultancy, Honoraria, Research Funding.

Introduction Despite the success of chimeric antigen receptor T (CART) cell therapy, it is limited by lower rates of durable responses related to inadequate CART cell expansion and trafficking and life-threatening complications such as cytokine release syndrome (CRS). Development of a strategy to efficiently track CART cells would allow the in vivo characterization of T cell expansion and trafficking to tumor sites as well as the development of strategies to potentially overcome these limitations. The sodium iodide symporter (NIS) is a sensitive reporter system that has been used for cell imaging in the clinic. Objectives NIS would be an efficient way to assess CART cell expansion, trafficking, and toxicity. Methods In vitro functions of CART cells were assessed by antigen specific proliferation, cytotoxicity, and cytokine production. NIS activity in vitro was evaluated by 125I uptake assay. In vivo imaging was performed using TFB PET/CT. CART cell trafficking assay was tested with OPM2 multiple myeloma (MM) xenografts and treated with either BCMA CART or NIS+BCMA CART cells. For CRS model, NSG mice were engrafted with patient-derived CD19+ acute lymphoblastic leukemia blasts. After the engraftment, mice were treated with either NIS+CART19 cells (5 × 106) or control. Results We generated NIS+CART19 and NIS+BCMA CART cells through dual transduction (Fig A) and revealed the exclusive 125I uptake in vitro (Fig B). In vitro functions of NIS+CART cells were equivalent to CART19 (Fig C). This indicates the incorporation of NIS into CART cells does not impair their antitumor activity. In vivo sensitivity assay revealed NIS+CART cells were detectable when cells were subcutaneously injected to NSG mice at a dose of 1.25 × 106 cells (Fig D). For in vivo trafficking assay, bioluminescence imaging (BLI) showed MM cells mainly engrafted in bones (Fig E). TFB PET confirmed the trafficking of NIS+BCMA CART cells to the bones, corresponding to BLI (Fig E). Both BCMA CART and NIS+BCMA CART cells exhibited similar antitumor activity. Finally, we explored whether TFB PET can detect CART massive expansion in vivo and predict CRS. One week after mice were treated with high dose NIS+CART19 cells, mice developed muscle weakness, hunched bodies, and weight loss (Fig F), which correlate with CRS. TFB PET revealed a significant uptake in the bone marrow, spleen, liver, and lungs (Fig G) of the diseased mice but not control mice. Flow cytometry revealed extensive infiltration of CART cells in the liver and spleen. This demonstrates the ability of TFB PET to detect NIS+CART cell expansion in vivo, correlating with the development of CRS. Conclusion Our results robustly show NIS+CART cells provides a sensitive, clinically applicable platform to image CART cells and to assess their expansion, trafficking to tumor sites, and the development of CRS. These studies illuminate a novel way to noninvasively assess CART cell functions in vivo.

Introduction Despite the remarkable activity of CD19 directed chimeric antigen receptor T cell (CART19) therapy in the treatment of B cell malignancies, limitations include neurotoxicity (NT) and cytokine release syndrome (CRS). Emerging literature suggests that inhibitory myeloid cells and their cytokines induce CAR-T cell toxicities and inhibit effector functions. GM-CSF was specifically identified as a critical cytokine in the development of NT and CRS. Neutralization of GM-CSF in preclinical models has been shown to prevent CRS, enhance CART anti-tumor activity, and reduce the presence of tumor associated macrophages. In addition, there appears to be a direct effect on CART19 cells. Objectives In this study, we aimed to evaluate the direct effect of GM-CSF on CART cells. Methods We used a guide RNA (gRNA) targeting exon 3 of GM-CSF in a CRISPR-Cas9 lentiviral vector to knock out GM-CSF during CART cell manufacturing. Edited and wildtype T cells and CART cells were sent for whole exome sequencing (WES) and RNA sequencing. We also used flow cytometry to assess the expression of GM-CSF receptors on CART cells, activated using CD3/CD28 beads or irradiated NALM6 cells. Results WES analysis revealed no significant difference in the single nucleotide variants or indel counts between GM-CSFk/o and GM-CSFwt CART19 (Fig 1A). WES was significant for only two alterations in the gene targeted by the gRNA (Fig 1B). This high efficiency and accuracy indicated that the improvement in CART function is unlikely related to an off-target effect of the gRNA and suggests a direct interaction between GM-CSF and CART cells as a potential mechanism behind the improved anti-tumor activity. Further investigation robustly indicates that while resting CART cells do not express any GM-CSF receptors, activated CART cells significantly upregulate both α and β subunits of the GM-CSF receptor. This finding was significant both when CART cells were activated through their T cell receptor (Fig 1C) or CAR (Fig 1D). This was also seen in GM-CSFk/o CART19 cells, indicating this is specifically induced by T cell stimulation. These data suggest a direct interaction between GM-CSF and upregulated GM-CSFR on activated CART cells. Finally, we sought to uncover the downstream changes resulting from this effect. Transcriptome interrogation of GM-CSFk/o CART19 revealed a distinct signature, including significant inhibition of the Fas death pathway (Fig 1E). This suggests a potential mechanism for enhanced CART19 activity following GM-CSF depletion. Conclusion Our results strongly indicate that CART cells increase expression of GM-CSF receptor subunits when activated, resulting in modulation of CART cell functions. Furthermore, GM-CSFk/o CART19 revealed a distinct transcriptome signature compared to GM-CSFwt CART19. These results illuminate a novel mechanism for a direct modulatory effect of GM-CSF on activated CART cells.

Introduction Cellular immunotherapy is a rapidly progressing field in multiple myeloma (MM). Multiple clinical trials have reported impressive efficacy of B cell maturation antigen (BCMA) directed chimeric antigen receptor cell therapy (BCMA CART) in MM. While trials demonstrated a high response rate, the durable response rate is around 30%. Most patients lose their CART cells, and the disease relapses within the first year, suggesting an inhibition by the MM tumor microenvironment (TME). Therefore strategies to overcome this inhibition would represent a major advance in this field. Cancer associated fibroblasts (CAFs) within the TME play a critical role in promoting tumor growth and immunosuppression. Objective CAFs from MM patients lead BCMA CART cell dysfunction and targeting both MM cells and CAFs can overcome this resistance. Methods CAFs were isolated from the bone marrow (BM) of MM patients and purified using anti fibroblast beads. MM-TME mouse model was established by injecting a 1:1 ratio of BCMA+ OPM2 (MM cell line) to CAFs. Five different CART cells were tested in this study. For single transduced CAR: BCMA, CS1, and fibroblast activation protein (FAP). For dual transduced CAR: BCMA-CS1 and BCMA-FAP CART. These were generated through the double transduction of two lentiviral vectors. Results BCMA CART cell proliferation assay showed inhibition of CART expansion in the presence of CAFs, and this was mediated by TGF-β (Fig A). MM-TME mouse model revealed a significant acceleration of MM progression (Fig B). To identify targets, we verified FAP expression on CAFs. Interestingly, there was a low level of CS1, but not BCMA expressed on CAFs (Fig C). Then, we evaluated the impact of CAFs on functions of BCMA CART cells compared to dual CART cells. When CART cells were stimulated with the BCMA+ MM cell line MM1S, in the presence of CAFs, the proliferation of BCMA CART cells, but not the dual CART cells was significantly inhibited (Fig A). Similarly, in the presence of CAFs, the production of key effector cytokines by BCMA CART cells, but not the dual CART cells was reduced (Fig D). Finally, we studied the impact of CAFs on CART cell functions in vivo. First, using OPM2 xenografts, treatment with BCMA CART cells was able to eradicate MM (Fig E). Then, the MM-TME model was used to assess the effect of targeting CAFs. Mice were treated with 1) control T cells, 2) BCMA CART cells, 3) BCMA-FAP CART cells, or 4) BCMA-CS1 CART cells. A low dose (1 × 106 iv) of CART cell was used to induce relapse. BCMA CART cells led to a transient antitumor activity in this model (mice died within 2 weeks), while dual CART cells resulted in durable remissions, a higher number of circulating T cells, and long term survival (Fig F). Conclusion We demonstrate for the first time that dual targeting both malignant plasma cells and the CAFs within the TME is a novel strategy to overcome resistance to CART cell therapy in MM.

Chimeric antigen receptor T-cell therapy (CART) is limited by the development of cytokine release syndrome (CRS) and neurotoxicity (NT). CRS is related to extreme elevation of cytokines and massive T cell expansion. Preliminary studies suggest that NT might be mediated by myeloid cells that cross the blood brain barrier. This is supported by correlative analysis from CART19 pivotal trials where CD14+ cell numbers were increased in the cerebrospinal fluid of patients that developed severe NT (Locke et al, ASH 2017). Thus, we aimed to investigate the role of GM-CSF neutralization in preventing CRS and NT after CART cell therapy via monocyte control. The human GM-CSF neutralizing antibody lenzilumab (Humanigen, Burlingame, California), which has been shown to be safe in phase II clinical trials, does not impair CART cell function in vitro (10 ug/mL) when CART19 cells are stimulated with the CD19+ Luciferase+ acute lymphoblastic leukemia (ALL) cell line NALM6. Lenzilumab results in enhanced CART cell antigen specific proliferation in the presence of monocytes. In vivo, NOD-SCID-g−/− mice were engrafted with high disease burdens of NALM6 and treated with low doses of CART19 or control T cells, in combination with lenzilumab or isotype control antibody. The combination of CART19 and lenzilumab does not impair CART cell activity in vivo (Fig 1A). The impact of GM-CSF neutralization on CART toxicities in a novel patient derived xenograft model was explored. NOD-SCID-g−/− mice were engrafted with primary ALL blasts (1-3 × 106 cells). Mice were treated with high doses of CART19 cells (2-5 × 106 iv) and developed CART cell related toxicities. The combination of CART19, lenzilumab (to neutralize human GM-CSF), and murine GM-CSF blocking antibody (to neutralize mouse GM-CSF) resulted in prevention of weight loss (Fig 1B), decrease in critical myeloid cytokines (Fig 1C-D), reduction of cerebral edema (Fig 1E), enhanced leukemic disease control in the brain (Fig 1F), and reduction in brain macrophages (Fig 1G). As CRISPR/Cas9 gene editing of the GM-CSF gene during the process of CART cell manufacturing would result in CART cells with innately reduced secretion of GM-CSF, we designed guide RNA targeting exon 3 of the GM-CSF gene to generate GM-CSFk/o CART19 cells. These CARTs produce significantly less GM-CSF upon activation but other T cell cytokine production is not inhibited (Fig 1H). Using the NALM6 high tumor burden relapse xenograft model as described above, GM-CSFk/o CART19 cells resulted in slightly enhanced disease control compared to CART19 cells (Fig 1I). These studies illuminate a novel approach to abrogate NT and CRS through GM-CSF blockade that also potentially enhances CART cell functions. Based on these results, we have designed a phase II clinical trial using lenzilumab as a modality to prevent CART related toxicities in patients with diffuse large B cell lymphoma.

Despite the remarkable results of CD19 directed chimeric antigen receptor T cell (CART19) therapy, the durable responses in B cell lymphoma and chronic lymphocytic leukemia (CLL) is limited. This may be due to the loss of CART persistence, poor trafficking and inhibition by the tumor microenvironment. Strategies to enhance CART function are thus needed. Recent data have shown that abnormal expression of receptor tyrosine kinase (RTK) AXL portends poor prognosis. Inhibition of AXL with TP0903, a high affinity AXL inhibitor, has been found to induce robust apoptosis of CLL B cells. We therefore examined the role of AXL inhibition with TP0903 on T cell and CART19 function. First, we investigated the effect of AXL inhibition on naive T cells. Cells stimulated with PMA/Ionomycin and cultured with TP0903 showed significant reduction of Th2 cytokines and inhibitory receptors (Fig 1a). Effector and regulatory T cells (Treg) treated with TP0903 showed a preferential reduction of Tregs (Fig 1b). Next, we investigated the influence of TP0903 on 41BB costimulated CART19. TP0903 led to polarization of CARTs into a Th1 phenotype when T cells were stimulated with the CD19+ mantle cell lymphoma (MCL) cell line JeKo or with leukemic B cells isolated from CLL patients (Fig 1c). TP0903 treatment also significantly downregulated inhibitory receptors on activated CARTs, including cytokine release syndrome (CRS) related cytokines (Fig 1c). The combination of CART19 and TP0903 yielded a synergistic cytotoxicity against JeKo in vitro (Fig 1d). We compared the transcriptome of activated CARTs treated with TP0903, and noted >100 genes that were differentially expressed compared to non-treated cells. Among these, cell junction, cell migration, and immune synapse related genes were significantly increased in activated CARTs treated with TP0903. To investigate the effect of AXL inhibition of CARTs with TP0903 in vivo, we established MCL xenografts via the injection of JeKo into NSG mice. The mice were then treated with vehicle alone, TP0903 alone, CART19 alone, or TP0903 + CART19. Three weeks after the treatment, mice were rechallenged with JeKo. Mice treated with CART19 and TP0903 rejected the JeKo challenge while mice previously treated with CART19 alone redeveloped JeKo, suggesting that AXL inhibition enhanced CART persistence (Fig 1e). Finally, we validated our findings in a phase I clinical trial of TP0903 (NCT02729298). T cells isolated from 3 cancer patients showed significant reduction of Tregs. This will be further investigated in a planned phase I clinical trial of TP0903 in relapsed/refractory CLL (NCT03572634). In summary, we showed for the first time that AXL inhibitior polarizes T cells into a Th1 phenotype, downregulates inhibitory receptors, reduces CRS associated cytokines and synergizes CARTs in B cell malignancies. These findings encourage further study of TP0903 as an enhancer of T cell immunotherapies.

Method Fourteen cases of young (under 66 years old) PCNSL who were treated at Anjo-Kosei Hospital between May 2002 and December 2011 enrolled in this study. Result Among 14 cases, 35–65 (median 56) years old, the pathorogical diagnosis are: 13 cases of diffuse large B cell lymphoma (DLBCL), 1 case of intravascular large B cell lymphoma (IVL), and 6 cases are treated by upfront auto PBSCT. The median follow-up was 38.7 months. Between auto-PBSCT and no-auto-PBSCT arms, there are no significant differences in the patient's background such as age (53.5 years old versus 58 years old), performance status, serum LDH (205 versus 198), serum sIL2R (436 versus 680). We checked the prognostic scoring system for PCNSL, but there are no differences between the two arms. In auto-PBSCT arm, they were treated by high-dose MTX-based therapy and high-dose AraC therapy, when they achieved CR/ near CR, they were carried out auto PBSCH. The conditioning regimen for auto PBSCT was LEED therapy in all cases. The overall survival at 4 years was superior in the auto-PBSCT arm (75.0% versus 41.7% P = 0.262). The relapse rate at 4 years was superior in the auto-PBSCT arm (25.0% versus 61.9% P = 0.273). In auto PBSCT arm, five cases maintain complete remissions and no one has severe complications such as leukoencephalopathy. In no-auto PBSCT arm, four cases are died from the relapse and only three cases maintain complete remission. Conclusion Our results emphasize the effectiveness and safety of upfront auto PBSCT to PCNSL.

Introduction Hematology malignancy is often complicated by many critical diseases including DIC. The resolution of DIC safely is one of the most important aspects in getting over hematological malignancy. We would like to report our comparative review of the administration of Recombinant Thrombomodulin (Recomodulin) versus Dalteparin Na (Fragmin) and this time, we would also report the possibility of reducing blood products such as fresh frozen plasma (FFP). Patient Thirteen patients (mean age 57.0 years, men/women 5/8, AML 7, APL 4, ALL 2) were administered recombinant thrombomodulin and 13 patients (mean age 50.5 years, men/women 8/5, AML 6, APL 4, ALL 3) were administered Dalteparin Na. Result The mean duration of therapies was 3.8 and 11.3 days, respectively. All patients has achieved DIC resolution, and the mean resolution time was 5.5 and 11.6 days (P = 0.020). The mean administration of FFP was 7.5 and 16.9 units (P = 0.091). The average of FDP, Fib, and JMHW DIC score has improved in both therapies. On the other hand, there were no changes in PT-INR and AT3. No bleeding and other adverse events were reported during both administration. Conclusion Recombinant thrombomodulin adminisitration is effective therapy rather than Dalteparin Na administration for patients with hematological malignancy and also tends to reduce the use of FFP.