First-in-Human Study of WT1 Recombinant Protein Vaccination in Elderly Patients with AML in Remission: A Single-Center Experience

Abstract Background Vaccination (vac) strategies to maintain remissions in AML have been pursued for decades. The usage of recombinant proteins instead of peptides allows a potential immune response to multiple epitopes, hence could be offered to all patients (pts) independent of HLA expression. Wilms' tumor 1 (WT1) protein is highly immunogenic and frequently overexpressed in AML, thus ranked as a very promising target for novel immunotherapies. Here we report a single-center experience of a phase I/II clinical trial (NCT01051063) of a first-in-human vac strategy based on WT1 recombinant protein (WT1-A10) together with vaccine adjuvant AS01 B in 5 elderly AML pts. Patients and Methods Key eligibility criteria: overexpression of WT1 transcripts in AML blasts at diagnosis (qRT-PCR); 1 or 2 induction chemotherapies, with partial remission (PR) or morphologic complete remission with incomplete blood count recovery (CRi). The vaccine consisted of WT1-A10, a truncated WT-1 protein retaining the N-terminus (amino acids 2-281) of full length WT1 protein (429 aa) linked to the first 11 amino acids of trimethylamine N-oxide reductase signal peptide via one histidine residue combined with the liquid AS01 B adjuvant. AS01 B is an Adjuvant System containing MPL (3-O-desacyl-4´-monophosphoryl lipid A), QS-21 (Quillaja saponaria Molina, fraction 21) and liposome (50µg MPL and 50µg QS-21). One human dose of WT1-A10 + AS01 B contained 200 μg of WT1-A10 antigen. Pts received the vaccine by i.m. injection. To assess cellular response, antigen-specific stimulation of cultured PBMCs was performed with a pool of 123 15mer peptides covering the entire WT1 (1μg/ml/peptide), together with irrelevant re-stimulation plus negative control peptide. CD4 + and CD8 + T cells were serially assessed by intracellular flow cytometry for their ability to produce both IFN-γ and TNF upon antigen stimulation. Results A total of 5 pts (median age 69, range 63-75) were enrolled on the WT1 protein-based vac study at our institution (Table 1), receiving a total of 62 vac after a median of 3 courses (1-5) of standard chemotherapy. The repeated vac had an acceptable safety profile and were thus well tolerated. 2/5 pts experienced therapy-related toxicity, injection site pain (CTCAE v.3, grade 2) and injection site inflammation (CTCAE v.3, grade 1). Symptoms were of mild / moderate severity and resolved completely. No hematologic toxicity was noted. With a median progression-free survival of 28.8 mths (range 1-59) and median overall survival (OS) of 35.4 mths (range 3-75) from the 1st vac, this older patient cohort showed above-average clinical outcome (Table 1), pointing to a potential clinical efficacy of WT1-based vac therapy. All vaccinated pts showed highly elevated WT1 ratios before WT1-based vac therapy and normal levels after vac (Fig. 1A). Two pts demonstrated early relapse after 3 WT1 protein-based vac, and clinical benefit was observed in 3 pts: one achieved complete and sustained measurable residual disease clearance (NPM1 ratios) during WT1 vac, resulting in molecular CR at the 18th vac. The pt died from unrelated reasons 5.5 years after initial diagnosis of AML, 3.5 years after the last WT1 vac, with continued molecular CR. One pt maintained long-term hematological and molecular remission over 59 mths, until molecular relapse occurred 11 mths after the final, 21 st vac. Interestingly, in one case, a complete clonal switch occurred at hematologic relapse following 18 vac, with loss of WT1 overexpression: while the clone at initial diagnosis harbored FLT3, NPM1 and SRSF2 mutations, BRAF, KRAS and STAG2 mutations were detected at relapse (Fig. 1B), pointing to an ongoing suppression of the WT1 expressing AML clone. Flow cytometry studies were conducted in one pt to elucidate specific cellular immune responses. We noted CD4 + T cell immune responses by strong IFN-γ and TNF expression (Fig. 1C), suggestive of efficient immune stimulation post-vac, while CD8 + T cells failed to upregulate these key cytokines. Conclusions This vac strategy showed good feasibility, with a very acceptable safety profile, and appeared to extend remissions beyond the expected duration, together with MRD clearance. Thus, our data provide evidence of potential clinical efficacy of WT1 protein-based vac therapy in AML pts, making this maintenance approach an attractive alternative to more complex strategies, particularly in elderly pts with comorbidities. Figure 1 Figure 1. Disclosures Döhner: Abbvie: Consultancy, Honoraria; Jazz Roche: Consultancy, Honoraria; Daiichi Sankyo: Honoraria, Other: Advisory Board; Janssen: Honoraria, Other: Advisory Board; Celgene/BMS: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Astellas: Research Funding; Agios and Astex: Research Funding. Schmitt: MSD: Membership on an entity's Board of Directors or advisory committees; TolerogenixX: Current holder of individual stocks in a privately-held company; Bluebird Bio: Other: Travel grants; Hexal: Other: Travel grants, Research Funding; Novartis: Other: Travel grants, Research Funding; Kite Gilead: Other: Travel grants; Apogenix: Research Funding. Lübbert: Teva: Research Funding; Janssen: Research Funding; Cheplapharm: Research Funding; Aristopharm: Research Funding; Syros: Honoraria; Pfizer: Honoraria; Janssen: Honoraria, Research Funding; Imago BioSciences: Honoraria; Hexal: Honoraria; Astex: Honoraria; Abbvie: Honoraria.

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Polatuzumab Vedotin Use before Chimeric Antigen Receptor T-Cell (CAR-T) Therapy in Aggressive Lymphoma: A US Single Center Experience

Blood ◽

10.1182/blood-2021-152313 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 3842-3842

Author(s):

Arushi Khurana ◽

Radhika Bansal ◽

Matthew Hathcock ◽

Adrienne Nedved ◽

Yucai Wang ◽

...

Keyword(s):

Board Of Directors ◽

Research Funding ◽

Advisory Board ◽

Single Center ◽

Infection Rates ◽

Bridging Therapy ◽

Advisory Committees ◽

Single Center Experience ◽

Significant Difference ◽

Car T

Abstract Background: Polatuzumab vedotin (Pola), an antibody drug conjugate targeting CD79b received FDA approval in combination with bendamustine and rituximab (Pola-BR) in June 2019. With CAR-T as destination therapy, the option of Pola-BR appears appealing with its superior efficacy and lack of potential interference with CAR-T due to different target antigens. However, clinical concerns remain regarding prolonged lymphopenia associated with benda and CAR-T manufacturing if used before apheresis. We reviewed the single center experience of all patients with exposure to polatuzumab around CAR-T for R/R aggressive NHL treated at Mayo Clinic Rochester. Methods: A review of patients that received at least one dose of Pola with the intent to proceed to CAR-T between July 1, 2019 and March 31st, 2021 at Mayo Clinic, Rochester were included. Response to therapy was based on 2014 Lugano criteria. Overall survival (OS) was defined as the time from CAR-T infusion to death, and event-free survival (EFS) as the time from CAR-T infusion to disease progression, next treatment, or death. Survival curves were calculated using Kaplan-Meier estimates, and were compared between subgroups using the log-rank test. Cox regression was used for multivariate analysis (MVA). Results: A total of 22 patients were identified during the study period. Of these 18 (82%), made it to CAR-T infusion (17 axi-cel, and 1 -tisa cel). 3 patients died due to progressive disease (PD) before CAR-T and one achieved complete remission (CR). In the pre-CAR-T Pola cohort (n = 22), the median age was 65.5 years (39-73), 50% were males, 96% had advanced stage and IPI ≥ 3. Median prior lines of treatment were 4.5 (2-6), 73% had primary refractory disease and 50% had myc rearrangement. 19 (86%) patients received Pola as bridging therapy and 8 were exposed to Pola before T-cell apheresis. Bendamustine was included in the treatment for 79% (15/19) for bridging therapy and 63% (5/8) with exposure pre-apheresis. For those in the bridging group, the overall response rate (ORR) was 26% (5/19), with one patient achieving CR with Pola-BR. Disease control (defined as those in a partial response [PR] or stable disease [SD]) was seen in 47% (9/19) patients. One of the 8 patients with pre-apheresis exposure to Pola, required an additional attempt at CAR-T manufacturing after the initial failure. At a median follow up of 48 weeks, the EFS and OS in 18 patient cohort with pre-CAR-T Pola exposure were 6.7 weeks (95% CI, 4.3-not reached [NR]) and 15 weeks (95% CI, 9.7-NR), respectively. At the data cut off (7/25/2021), 78% patients had died. As traditional chemo for bridging is a particularly poor prognostic group, we compared Pola-BR bridging group (n = 15), to other traditional chemo bridge group (n = 16) in our CAR-T database. Both groups had comparable baseline characteristics as shown in Table 1 except for higher proportion of patients with B-symptoms in the Pola-BR group at time of CAR-T. There was also no difference in the inflammatory markers (CRP and ferritin) at LD or peak level after CAR-T. Table 2 shows outcomes between the 2 groups with comparable any grade CRS, neurotoxicity, pre and post CAR-T infection rates. Best response ORR to CAR-T was higher in the other chemo group vs. Pola BR (81.2% vs. 33%, p = 0.027). There was a significant difference in the 6-month OS rate (other 81.3% [95%CI, 54.5-96] vs. pola 33.3% [95%CI, 11.8- 61.6], p = 0.007) but no significant difference in the 6-month EFS rate (other 37.5% [95%CI, 15.2-64.6%] vs. pola 13.3% [95%CI, 1.7-40.5%] p = 0.12) between the 2 groups (figure 1). On univariate analysis within the chemo type bridging cohort (Pola-BR + other traditional chemo, n = 31), presence of B-symptoms (HR 4.72, p = 0.002), ECOG PS > 2 at CAR-T (HR 6.75, p = 0.0008), and type of bridge therapy (pola HR 6.57, p = 0.009) were associated with worse OS whereas a response to bridge (PR+SD, HR 0.39, 0.031) was favorable. On MVA, association was maintained for bridge type (pola, p <0.001) and response to bridge (p <0.001). Discussion: Pola based bridge was feasible in this US based cohort without significant issues with CAR-T manufacturing or increased infection rates. However, in this retrospective analysis, use of Pola-BR was associated with inferior outcomes compared to other traditional chemotherapy options. Future studies are required to elucidate whether these difference in outcomes stem from a biological basis versus bias in patient selection. Figure 1 Figure 1. Disclosures Wang: TG Therapeutics: Membership on an entity's Board of Directors or advisory committees; MorphoSys: Research Funding; Incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding; Eli Lilly: Membership on an entity's Board of Directors or advisory committees; LOXO Oncology: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Genentech: Research Funding; InnoCare: Research Funding. Paludo: Karyopharm: Research Funding. Bennani: Kymera: Other: Advisory Board; Vividion: Other: Advisory Board; Kyowa Kirin: Other: Advisory Board; Daichii Sankyo Inc: Other: Advisory Board; Purdue Pharma: Other: Advisory Board; Verastem: Other: Advisory Board. Ansell: Bristol Myers Squibb, ADC Therapeutics, Seattle Genetics, Regeneron, Affimed, AI Therapeutics, Pfizer, Trillium and Takeda: Research Funding. Lin: Bluebird Bio: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Merck: Research Funding; Kite, a Gilead Company: Consultancy, Research Funding; Novartis: Consultancy; Janssen: Consultancy, Research Funding; Juno: Consultancy; Vineti: Consultancy; Takeda: Research Funding; Gamida Cell: Consultancy; Legend: Consultancy; Sorrento: Consultancy.

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The Immunomodulatory Effect of Triptolide on Mesenchymal Stem Cells in Vitro

Blood ◽

10.1182/blood-2019-125046 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 5011-5011

Author(s):

Haiping He ◽

Atsuko Takahashi ◽

Yuki Yamamoto ◽

Akiko Hori ◽

Yuta Miharu ◽

...

Keyword(s):

Stem Cells ◽

T Cells ◽

Cd8 T Cells ◽

Research Funding ◽

Complete Medium ◽

Surface Markers ◽

Rt Pcr ◽

Tnf Α ◽

Ifn Γ

Background: Mesenchymal stromal cells (MSC) are known to have the immunosuppressive ability and have been applied in clinic to treat acute graft-versus-host disease (GVHD), as one of severe complications after hematopoietic stem cells transplantation (HSCT) in Japan. However, MSC are activated to suppress the immune system only upon the stimulation of inflammatory cytokines and the clinical results of MSC therapies for acute GVHD are varied. It is ideal that MSC are primed to be activated and ready to suppress the immunity (=priming) before administration in vivo. Triptolide (TPL) is a diterpene triepoxide purified from a Chinese herb - Tripterygium Wilfordii Hook F (TWHF). It has been shown to possess anti-inflammatory and immunosuppressive properties in vitro. In this study, we aim to use TPL as the activator for umbilical cord-derived MSC (UC-MSC) to entry stronger immunosuppressive status. Methods: The proliferation of UC-MSC with TPL at the indicated concentrations for different time of 24, 48, 72, and 96 hours. Cell counting kit-8(CCK-8) was added in the culture medium to detect cell toxicity and the absorbance was measured using microplate reader. Flow cytometry was used to identify the MSC surface markers expression. TPL-primed UC-MSC were once replaced with fresh medium and co-culture with mixed lymphocyte reaction (MLR) consisted with mononuclear cells (MNCs) stained with CFSE and irradiated allogenic dendritic cell line (PMDC05) in RPMI 1640 medium supplemented with 10 % FBS (complete medium). IDO-1, SOD1, and TGF-β gene expression in TPL-primed UC-MSC and UC-MSC induced by 10 ng/ml IFN-γ and/or 15 ng/ml TNF-α were evaluated by RT-PCR. PDL1 and PDL2 expression in TPL-primed UC-MSC and UC-MSC in response to IFN-γ and/or TNF-α were checked by Flowjo. Results: Exposure of TPL for UC-MSC for 72hour at the concentration above 0.1 μM resulted in the cell damage significantly. Therefore, we added TPL in UC-MSC at 0.01μM of TPL for up to 48 hours, then washed thourouphly for the following culture for experiments. To evaluate the influence of TPL on the surface markers of UC-MSC, we cultured UC-MSC for 4 hours in complete medium following culture with 0.01μM of TPL for 20 hours (TPL-primed UC-MSC). TPL-primed UC-MSC revealed positive for CD105, CD73, and CD90, negative for CD45, CD34, CD14 or CD11b, CD79α or CD19 and HLA-DR surface molecules as same as the non-primed UC-MSC. In MLR suppression by UC-MSC, the TPL-primed UC-MSC activity revealed stronger anti-proliferative effect on the CD4+ and CD8+ T cells activated by allogeneic DC than those of non-primed UC-MSC in MLR. Furthermore, the TPL-primed UC-MSC promoted the expression of IDO-1, SOD1 and TGF-β in response to IFN-γ+/-TNF-α by RT-PCR and enhanced the expression of PD-L1 by FACS analysis. Discussion:In this study, we found the TPL-primed UC-MSC showed stronger antiproliferative potency on CD4+ and CD8+ T cells compared with non-primed UC-MSC. TPL-primed UC-MSC promoted the expression of IDO-1, SOD1 and TGF-β stimulated by IFN-γ+/-TNF-α, although TPL alone did not induce these factors. Furthermore, we found that the PD1 ligand (PD-L1) was induced in TPL-primed UC-MSC, likely IFN-γ enhanced the PD-L1 expression, evaluated by flowcytometry. These results suggested that TPL-primed UC-MSC seemed more sensitive to be activated as the immunosuppressant. Here, we firstly report the new function of TPL to induce the upregulation of immunosuppressive effect, although the mechanisms of TPL inhibition to MSC need to be explore. Conclusively, TPL-primed UC-MSC might be applied for the immunosuppressive inducer of MSC. Figure Disclosures He: SASAGAWA Medical Scholarship: Research Funding; IMSUT Joint Research Project: Research Funding. Nagamura:AMED: Research Funding. Tojo:AMED: Research Funding; Torii Pharmaceutical: Research Funding. Nagamura-Inoue:AMED: Research Funding.

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The effect of Kefir on The Immune Response of Healthy Volunteers In Vitro

Journal of Agromedicine and Medical Sciences ◽

10.19184/ams.v3i2.5067 ◽

2017 ◽

Vol 3 (2) ◽

pp. 28

Author(s):

Desie Dwi Wisudanti

Keyword(s):

Immune Response ◽

T Cells ◽

Immune Responses ◽

Healthy Volunteers ◽

Cd8 T Cells ◽

Cd4 T Cells ◽

Fermented Milk ◽

Bioactive Components ◽

Ifn Γ

Kefir is a functional foodstuff of probiotics, made from fermented milk with kefir grains containing various types of beneficial bacteria and yeast. There have been many studies on the effects of oral kefir on the immune system, but few studies have shown the effect of bioactive components from kefir (peptides and exopolysaccharides/ kefiran), on immune responses. The purpose of this study was to prove the effect of kefir supernatant from milk goat on healthy immune volunteer response in vitro. The study was conducted on 15 healthy volunteers, then isolated PBMC from whole blood, then divided into 5 groups (K-, P1, P2, P3 and P4) before culture was done for 4 days. The harvested cells from culture were examined for the percentage of CD4+ T cells, CD8+ T cells, IFN-γ, IL-4 using flowsitometry and IL-2 levels, IL-10 using the ELISA method. The results obtained that kefir do not affect the percentage of CD4+ T cells and CD8+ T cells. The higher the concentration of kefir given, the higher levels of secreted IFN- γ and IL-4, but a decrease in IL-2 levels. Significant enhancement occurred at levels of IL-10 culture PBMC given kefir with various concentrations (p <0.01), especially at concentrations of 1%. These results also show the important effects of kefir bioactive components on immune responses. The conclusion of this study is that kefir can improve the immune response, through stimulation of IL-10 secretion in vitro.

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Efficacy of Subsequent Therapies in Multiple Myeloma Patients after Progression on a BCMA Targeting Therapy: A Single-Center Experience

Blood ◽

10.1182/blood-2020-141637 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 11-13

Author(s):

Barry Paul ◽

Myra Robinson ◽

Kristen Cassetta ◽

Daniel Slaughter ◽

Jordan Robinson ◽

...

Keyword(s):

Clinical Trial ◽

Multiple Myeloma ◽

Overall Survival ◽

Research Funding ◽

Subsequent Treatment ◽

Single Center ◽

Targeting Therapy ◽

Single Center Experience ◽

Best Response ◽

Car T

Background: Targeting B-cell maturation antigen (BCMA) with antibody-drug conjugates (ADCs), bispecific antibodies, or chimeric antigen receptor t-cells (CAR-Ts) has proven safe and effective in recent clinical trials, but relapses remain common. As most patients treated with BCMA targeting therapies are refractory to conventional anti-myeloma therapies, management of these patients poses unique challenges once they progress, with no data available to guide subsequent therapies. Methods: We performed a retrospective chart review of all relapsed refractory multiple myeloma (RRMM) patients at our institution who progressed while on or after a BCMA targeting therapy and were treated with subsequent therapies. We evaluated the best response achieved and overall survival (OS) measured from progression on BCMA targeting therapies. Kaplan Meier methods were used to estimate OS curves and landmarks between classes of BCMA targeting therapy received (ADC, bispecific antibody or CAR-T), and by type of subsequent therapy. Results: At a median follow up of 6 months, a total of 47 patients were treated with a BMCA targeting therapy. Of those, a total of 21 (44.7%) patients have progressed, with 18 (38.3%) receiving another therapy. Twelve-month overall survival of the patients who received a subsequent treatment was 51.1% (figure 1a), but varied considerably based on the class of BCMA therapy they received (figure 1b). Patients who progressed after a BCMA CAR-T had the best OS (N =2, 6 mo OS: 100%, 12 mo OS: Of the 18 patients who progressed and were treated with subsequent therapies, 7 (38.9%) received 2 lines of therapy, 5 (27.8%) received 3 lines of therapy, and 1 patient (5.6%) received 5 lines of therapy. In the first relapse, 4 (22.2%) patients received infusional chemotherapy with CAR-D PACE or CAR-DCEP, 4 (22.2%) received the combination of elotuzumab, pomalidomide, and dexamethasone (Elo-Pd; one of which was first treated with CAR-DCEP), 3 (16.7%) received selinexor based regimens. The best response seen after first-line post BCMA treatment was a partial response (PR) in 5 (27.8% of patients), whereas 8 (61.5%) patients who received second-line treatment post-BCMA therapy had a PR or better, including 3 (23.1%) who had a very good partial response (VGPR). In the third line post-BCMA, 1 (16.7%) had a VGPR, while 1 (16.7%) had stable disease as their best response. The use of Elo or Dara after anti-BCMA progression seemed to correlate with improved OS (see figure 1c below). While all these patients were Elo naïve, the majority (94.4%) were previously Dara exposed. Conclusions: Our data demonstrate that many RRMM patients who progress on BCMA targeting therapies still derive benefit from subsequent treatment. Early evidence from our experience suggests a survival advantage with monoclonal antibody-based therapies even in patients who had previously been exposed to these agents-suggesting a possible resensitization with BCMA directed therapy. Although our dataset is a single-center experience, to our knowledge it represents the first report of post-BCMA exposed management of RRMM and provides valuable insight into the treatment of this challenging and ever-expanding population. Disclosures Paul: Bristol-Myers Squibb: Other: Stock Ownership (prior employee); Amgen: Consultancy, Speakers Bureau; Regeneron: Membership on an entity's Board of Directors or advisory committees. Bhutani:BMS: Other: Clinical trial funding to institute, Speakers Bureau; Takeda: Other: Clinical trial funding to institute, Speakers Bureau; Prothena: Other: Clinical Trial Funding to Institute; Amgen: Speakers Bureau; MedImmune: Other: Clinical Trial Funding to Institute; Sanofi Genzyme: Consultancy; Janssen: Other: Clinical Trial Funding to Institute. Voorhees:Adaptive Biotechnologies: Other: Personal fees; Bristol-Myers Squibb: Other: Personal fees; Celgene: Other: Personal fees; Janssen: Other: Personal fees; Novartis: Other: Personal fees; Oncopeptides: Other: Personal fees; TeneoBio: Other: Personal fees; Levine Cancer Institute, Atrium Health: Current Employment. Usmani:Celgene: Other; Janssen: Consultancy, Honoraria, Other: Speaking Fees, Research Funding; SkylineDX: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Merck: Consultancy, Research Funding; Incyte: Research Funding; Pharmacyclics: Research Funding; Array Biopharma: Research Funding; GSK: Consultancy, Research Funding; Takeda: Consultancy, Honoraria, Other: Speaking Fees, Research Funding; Sanofi: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy; BMS, Celgene: Consultancy, Honoraria, Other: Speaking Fees, Research Funding; Amgen: Consultancy, Honoraria, Other: Speaking Fees, Research Funding. Atrash:BMS, Jansen oncology, Sanofi: Speakers Bureau; Takeda, Amgen, Karyopharm, BMS, Sanofi, Cellactar, Janssen and Celgene: Honoraria; Amgen, GSK, Karyopharm.: Research Funding.

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Identification of the AAV2 Capsid CD8+ T Cell Epitope in C57BL/6 Mice.

Blood ◽

10.1182/blood.v104.11.3188.3188 ◽

2004 ◽

Vol 104 (11) ◽

pp. 3188-3188

Author(s):

Denise E. Sabatino ◽

Federico Mingozzi ◽

Haifeng Chen ◽

Peter Colosi ◽

Hildegund C.J. Ertl ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Immune Responses ◽

Capsid Protein ◽

Cd8 T Cells ◽

Cell Epitope ◽

T Cell Response ◽

Cd8 Cells ◽

Media Control ◽

Ifn Γ

Abstract Recently, a clinical trial for adeno-associated virus serotype 2 (AAV2) mediated liver directed gene transfer of human Factor IX to subjects with severe hemophilia B revealed that two patients developed transient asymptomatic transaminitis following vector administration. Immunology studies in the second patient demonstrated a transient T cell response to AAV2 capsid peptides suggesting that the immune response to the AAV capsid may be related to the transient transaminitis. We hypothesized that the observations made in the human subjects were due to a CD8 T cell response to AAV2 capsid protein. Preclinical studies in mice and dogs, which are not naturally infected by wild type AAV2 viruses, did not predict these findings in the clinical study. Thus, we developed a mouse model in which we were able to mimic this phenomenon (Blood 102:493a). In an effort to further characterize the immune responses to AAV2 capsid proteins in this mouse model, we identified the T cell epitope in the AAV capsid protein recognized by murine C57Bl/6 CD8 T cells. A peptide library of AAV2 VP1 capsid peptides (n=145) that were synthesized as 15mers overlapping by 10 amino acids were divided into 6 pools each containing 24–25 peptides. C57Bl/6 mice were immunized intramuscularly with an adenovirus expressing AAV2 capsid protein. Nine days later the spleen was harvested and intracellular cytokine staining (ICS) was used to assess release of IFN-γ from CD8 T cells in response to 6 AAV2 capsid peptide pools. ICS demonstrated CD8 cells from mice immunized with Ad-AAV2 produced IFN-γ (3.5% of the CD8 cells) in response to Pool F (amino acid 119–145) while no IFN-γ release in CD8 cells was detected with Pool A to E (mean 0.28%±0.25%) compared to the media control (0.16%). This detection of IFN-γ release from CD8 T cells indicates a specific proliferation to a peptide(s) within this peptide pool (Pool F). A matrix approach was used to further define which peptide(s) contained the immunodominant epitope. Eleven small peptide pools of Pool F were created in which each peptide was represented in 2 pools. ICS of splenocytes from immunized (Ad-AAV2 capsid) C57Bl/6 mice demonstrated IFN-γ response from CD8 cells to 3 of the matrix pools corresponding to peptide 140 (PEIQYTSNYNKSVNV) and 141 (TSNYNKSVNVDFTVD) compared with media controls. To determine the exact peptide sequence that binds to the MHC Class I molecule, 9 amino acid peptides (n=7) were created that overlap peptide 140 and 141. Peptide SNYNKSVNV showed positive staining for both CD8 and IFN- γ(3.2%) compared with the six other peptides (0.14%±0.08%), media control (0.08%) and mice that were not immunized (0.11%). This epitope lies in the C terminus of the AAV2 VP1 capsid protein. Current studies using strains of mice with different MHC H2 haplotypes will allow us to determine which of the C57Bl/6 MHC alleles the epitope binds. These findings will provide us with a powerful tool for assessing immune responses to AAV capsid in the context of gene therapy. Specifically, they will allow us to determine how long immunologically detectable capsid sequences persist in an animal injected with AAV vectors. This in turn will provide a basis for a clinical study in which subjects are transiently immunosuppressed, from the time of vector injection until capsid epitopes are no longer detectable by the immune system.

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Phagocytosis May Be a Regulatory Mechanism for Myeloid Dendritic Cells to Terminate Type 1 CD8+ T Cells.

Blood ◽

10.1182/blood.v114.22.1654.1654 ◽

2009 ◽

Vol 114 (22) ◽

pp. 1654-1654

Author(s):

Young-June Kim ◽

Hal E. Broxmeyer

Keyword(s):

T Cells ◽

Immune Responses ◽

Cd8 T Cells ◽

Phagocytic Activity ◽

Regulatory Mechanism ◽

Gm Csf ◽

T Cell Immune Responses ◽

Ifn Γ

Abstract Abstract 1654 Poster Board I-680 CD8+ cytotoxic T cells are often ‘exhausted’ by programmed death-1 (PD-1) signaling, and subsequently the functions of these cells are terminated especially in a tumor environment or upon chronic HIV or HCV infection. Subsets of myeloid cells referred to as myeloid derived suppressor cells (MDSC) or regulatory dendritic cells (DCs) have been implicated in inducing exhaustion or termination of effector CD8+ T cells. To this end, we developed various myeloid-derived dendritic cell (DC) types in vitro from human CD14+ monocytes using M-CSF or GM-CSF in the presence of IL-4 with/without other cytokines, and characterized these DCs with respect to their capacity to induce PD-1 expression on and exhaustion of CD8+ T cells. We then assessed their impact on longevity of CD8+ T cells following coculture. Myeloid DCs developed in vitro with M-CSF and IL-4 for 5 days (referred to as M-DC) did not express ligand for PD-1 (PD-L1) nor did they induce PD-1 on CD8+ T cells. Thus, using M-DCs as starting cells, we sought determinant factors that could modulate M-DCs to express PD-L1 and thereby induce exhaustion of CD8+ T cells. In order to better monitor exhaustion processes, we incubated human peripheral CD8+ T cells for 5 days in the presence of IL-15, an important cytokine for maintaining viability, before coculture. M-DCs showed little impact on exhaustion or longevity of the CD8+ T cells. IL-10 converted M-DC into a distinct myeloid DC subset (referred to as M-DC/IL-10) with an ability to express PD-L1 as well as to induce PD-1 on cocultured CD8+ T cells. M-DC/IL-10 cells markedly suppressed proliferation of cocultured CD8+ T cells. M-DC/IL-10 cells were morphologically unique with many granules and filamentous structures around the cell periphery. These IL-10 effects on M-DC were completely abrogated in the presence of TNF-á. M-DC/IL-10 cells could be further differentiated into another myeloid DC subset in the presence of IFN-γ (referred to as M-DC/IL-10/IFN-γ) with an ability to express even higher levels of PD-L1 compared to M-DC/IL-10 cells. The most remarkable effect of M-DC/IL-10/IFN-γ cells on cocultured CD8+ T cells was a dramatic loss of CD8+ T cells. Light and confocal microscopic observations indicated that loss of CD8+ T cells was due to phagocytosis by M-DC/IL-10/IFN-γ cells. As IFN-γ, a type 1 cytokine which is induced in CD8+ T cells by IL-12 is essential for phagocytosis, we tested whether IL-12 treatment of CD8+ T cells could further enhance phagocytosis induced by M-DC/IL-10/IFN-γ cells. Indeed, IL-12 treatment greatly increased numbers of phagocytosed CD8+ T cells. In contrast, IL-4 treated CD8+ T cells became resistant to phagocytosis, suggesting IFN-γ producing (type1) CD8+ T cells may be primary target cells for the M-DC/IL-10 cells mediated phagocytosis. CD4+ T cells were not as susceptible as CD8+ T cells to phagocytosis. We failed to detect such phagocytic activity induced by prototype DCs generated with GM-CSF and IL-4. Phagocytic activity was not inhibited by various arginase-1 inhibitors suggesting that nitric oxide signaling may not mediate phagocytic activity. Neutralizing antibody to PD-L1 slightly but significantly lowered phagocytic activity suggesting that PD-L1/PD-1 interaction may be partially involved in this process. Myeloid DCs are thought to be immunogenic, actively inducing T cell immune responses. Our results demonstrate that myeloid DCs may play suppressive roles as well through induction of phagocytic activity, especially against IFN-γ producing CD8+ T cells. This may serve as a regulatory mechanism for type 1 CD8+ T cell immune responses in an IL-10 enriched microenvironment. Disclosures No relevant conflicts of interest to declare.

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Differential Roles of Interleukin 15 mRNA Isoforms Generated by Alternative Splicing in Immune Responses in Vivo

Journal of Experimental Medicine ◽

10.1084/jem.191.1.157 ◽

2000 ◽

Vol 191 (1) ◽

pp. 157-170 ◽

Cited By ~ 109

Author(s):

Hitoshi Nishimura ◽

Toshiki Yajima ◽

Yoshikazu Naiki ◽

Hironaka Tsunobuchi ◽

Masayuki Umemura ◽

...

Keyword(s):

T Cells ◽

Alternative Splicing ◽

Transgenic Mice ◽

Immune Responses ◽

Cd8 T Cells ◽

Salmonella Infection ◽

Mrna Isoforms ◽

Interleukin 15 ◽

Ifn Γ

At least two types of interleukin (IL)-15 mRNA isoforms are generated by alternative splicing at the 5′ upstream of exon 5 in mice. To elucidate the potential roles of IL-15 isoforms in immune responses in vivo, we constructed two groups of transgenic mice using originally described IL-15 cDNA with a normal exon 5 (normal IL-15 transgenic [Tg] mice) and IL-15 cDNA with an alternative exon 5 (alternative IL-15 Tg mice) under the control of an MHC class I promoter. Normal IL-15 Tg mice constitutionally produced a significant level of IL-15 protein and had markedly increased numbers of memory type (CD44high Ly6C+) of CD8+ T cells in the LN. These mice showed resistance to Salmonella infection accompanied by the enhanced interferon (IFN)-γ production, but depletion of CD8+ T cells exaggerated the bacterial growth, suggesting that the IL-15–dependent CD8+ T cells with a memory phenotype may serve to protect against Salmonella infection in normal IL-15 Tg mice. On the other hand, a large amount of intracellular IL-15 protein was detected but hardly secreted extracellularly in alternative IL-15 Tg mice. Although most of the T cells developed normally in the alternative IL-15 Tg mice, they showed impaired IFN-γ production upon TCR engagement. The alternative IL-15 transgenic mice were susceptible to Salmonella accompanied by impaired production of endogenous IL-15 and IFN-γ. Thus, two groups of IL-15 Tg mice may provide information concerning the different roles of IL-15 isoforms in the immune system in vivo.

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Oncogenic-Drivers Dictate Immune Responses to Control Disease Progression in Acute Myeloid Leukaemia

Blood ◽

10.1182/blood-2018-99-112009 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 904-904

Author(s):

Rebecca Austin ◽

Megan Bywater ◽

Jasmin Straube ◽

Leanne T Cooper ◽

Madeleine Headlam ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Immune Responses ◽

Nk Cells ◽

Research Funding ◽

T Cell Subsets ◽

Transcriptional Analysis ◽

Immune Control ◽

Immune Microenvironment ◽

Ifn Γ

Abstract Immunotherapy has revolutionised therapeutic approaches to fight cancer and, in certain diseases dramatically improves survival. Clinical responses to immune checkpoint blockade have in part been attributed to high mutational burden of tumours such as melanoma. High-risk acute myeloid leukaemia (AML) is defined by molecular and cytogenetic factors. AML has a low prevalence of somatic mutations and is predicted to have low immunogenicity. We aimed to determine how AMLs driven from different classes of oncogenes interact with endogenous anti-leukemic immune responses. Methods and Results We generated three oncogenically distinct models of AML: BCR-ABL+NUP98-HOXA9 (BA/NH9), MLL-AF9 (MA9), and AML1-ETO+NRASG12D (AE/NRAS), using retroviral transduced bone marrow transplanted into immune-competent, non-irradiated C57BL/6J (B6) mice or immune-deficient Rag2-/-γc-/- mice. Immunologic control of AML was dependent on the driver oncogene, as AE/NRAS AML was effectively controlled in B6, but not Rag2-/-γc-/-recipients, whereas survival of BA/NH9 AML recipients was similar between B6 and Rag2-/-γc-/-. MA9 AML had an intermediate phenotype (Figure 1A-C). To examine the mechanisms underlying immune escape in AE/NRAS, AML from immune-deficient or immune-competent hosts, was passaged through immune-competent hosts. Prior exposure to an intact immune system dramatically accelerated disease progression of AE/NRAS AML in subsequent B6 recipients, but this was not seen in passage through Rag2-/-γc-/- recipients. This demonstrates specific, functional immunoediting of AML resulting in evasion of immune control. Despite evidence of disease attenuation in immune competent hosts, functional immunoediting was not observed in MA9 AML. Antibody-mediated immune cell depletion experiments demonstrated that natural killer (NK) cells and T cells both contribute to the control AE/NRAS AML, whereas MA9 immune control was dependent on NK cells. As immunoediting was only seen in AE/NRAS model, this suggests that functional immunoediting in this model is primarily mediated by T cells. To characterise the mechanisms regulating immunoediting, we integrated proteomic and transcriptional analysis of immunoedited and non-immunoedited AE/NRAS AML. There was strong correlation between increased protein expression and transcriptional regulation. There was distinct regulation of inflammatory pathways between immunoedited and non-immunoedited AML. Immunoedited AE/NRAS cells showed increased IFN-γ-dependent response signatures, consistent with direct targeting of the leukemic cells by the immune system. Transcriptional analysis also showed modulation of expression of immune checkpoint molecules including upregulation of suppressive molecules Tim-3 and CD39 and downregulation of activating ligand CD137L. These findings were confirmed by cell-surface flow cytometry. Immunoedited AE/NRAS downregulated RAS signalling transcriptionally, with coordinate activation of MYC targets. In the murine AE/NRAS model, CD4+ and CD8+ T effector memory (TEM) cells (CD44+ CD62L-) demonstrated increased PD-1 expression compared to naïve mice. In addition, mice with high disease burden also had increased frequency of T cells co-expressing exhaustion markers PD-1, Tim-3 and LAG-3, consistent with suppression of the anti-leukemic effector immune response. To understand if these findings were relevant to AML in the clinic, we obtained single cell RNA-sequencing data from the CD45+ CD34- non-leukemic fraction of bone marrow in a patient with AML1-ETO AML at diagnosis compared to that in normal marrow. Single cell type classification and clustering using tSNE demonstrated remodelling of the immune microenvironment in AML with loss of NK cells, pre-B cells and skewing of T cell subsets. There was depletion of CD8+ TEM cells and greater proportions of CD4+ and CD8+ TEM cells expressing activation and exhaustion markers (IFN-γ, PD-1, LAG-3, TIM-3). Conclusions These data demonstrate that immune responses in AML are oncogene-specific and provide evidence that AE/NRAS AML cells undergo immunoediting over time in the presence of a competent immune microenvironment. Since AML is associated with alterations in T cell subsets, and changes in T cell activation and exhaustion states, these findings may inform translational strategies to use immunotherapies for patients with AML. Disclosures Smyth: Bristol Myers Squibb: Other: Research agreement; Tizona Therapeutics: Research Funding. Lane:Janssen: Consultancy, Research Funding; Celgene: Consultancy; Novartis: Consultancy.

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Optimum Imatinib Exposure Have Possibility of Leading to Appropriate Immune Response after Imatinib Discontinuation in CML Patients

Blood ◽

10.1182/blood-2019-130300 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 192-192

Author(s):

Yuki Fujioka ◽

Hiroyoshi Nishikawa ◽

Naoto Takahashi

Keyword(s):

T Cells ◽

T Cell ◽

Immune Responses ◽

Cd8 T Cells ◽

Research Funding ◽

Pharmaceutical Research ◽

T Cell Response ◽

Vitro Assay ◽

Kinetics Of

Introduction: Imatinib, the first tyrosine kinase inhibitor (TKI), has dramatically improved the prognosis of chronic myeloid leukemia (CML) patients. Recently, many trials of TKI discontinuation revealed that approximately 40% to 60% of CML patients who treated long time TKI therapy reached the treatment free remission (TFR), thus now TFR is proposed as one of the goals in CML treatment. Achieving deep molecular response (DMR) by TKI therapy is a minimum requirement of challenge to TKI discontinuation in CML patient, actually CML patients with molecular residual disease (MRD) showed worse consequence than undetectable MRD (IJH 2017). On the other hand, it was known that some patients have continued TFR with detectable BCR-ABL fusion gene, these patients hadn't shown indubitable molecular relapse while BCR-ABL+ malignant cells continued to exist for prolonged time. We hypothesized that the malignant cells were eliminated by host immune systems in these fluctuated patients. Here, we focused on T-cell response, so we analyzed T-cell related markers to identify biomarkers that can predict patients which can continue TFR or not in Japanese CML patients. Furthermore, we confirmed the action of imatinib for T-cell response in vitro. Methods: Japanese CML patients treated with imatinib for at least three years and confirmed in DMR for at least two years were eligible. Patients who received other TKI or stem cell transplantations were excluded. Patients were re-confirmed in MR4.5 before discontinue imatinib and they were sampled peripheral blood at pre- and 1, 3 months after stopping imatinib (figure 1). Peripheral blood mononuclear cells (PBMCs) were subjected to staining with T-cell markers and analyzed by mass cytometry and flowcytometry. Plasma were subjected to detecting Imatinib trough concentrations. Purchased PBMCs of healthy individuals were cultured and analyzed by flowcytometry in vitro assay. Results: Samples of 68 CML patients were analyzed. We classified these CML patients into two groups (Non-retreatment and Retreatment groups) by clinical courses after stopping imatinib (figure 2). Frequency of CD4+ T cells and CD8+ T cells in CD3+ T cells were no difference between both groups. FoxP3+CD4+ regulatory T cells (Treg) were also no difference between both groups, but kinetics of Treg, especially Fraction II (Fr.II : FoxP3hiCD45RA-) of Treg from Pre-stopping imatinib to 1 month after stopping imatinib significantly increased in non-retreatment groups. Kinetics of Treg / CD8+ T cells ratio also significantly increased in non-retreatment groups, and predicted curve made by these kinetics of each groups were significant (figure 3). The expression of PD-1 or other suppressive co-stimulatory molecules in CD8+ T cells of non-retreatment groups at after stopping imatinib had tendency to decrease. Phosphorylated LCK in CD8+ T cells of non-retreatment groups at after stopping imatinib had tendency to increase. Next, we did in vitro assay to confirm the effect of pre-treatment of imatinib in imatinib free T cells. Pre-treatment of imatinib suppressed the proliferations of Treg Fr.II after TCR stimulation dose dependently, but not CD8+ T cells (figure 4). Frequency of phosphorylated LCK in Treg Fr.II increased after TCR stimulation even if pre-treated imatinib at reasonable dose, but didn't increased under the condition of high dose imatinib. Conclusion: Treg population and Treg / CD8+ T cells ratio in PBMCs elevated after stopping imatinib in non-retreatment groups of CML patients. Population of CD8+ T cells showed no differences in two groups but CD8+ T cells were tending to activate after stopping imatinib in non-retreatment groups. These data indicate that the kinetics of Treg after stopping imatinib connect with the immune response of imatinib discontinued CML patients. In vitro data indicate that Treg were more sensitive for imatinib treatment than CD8+ T cells, so kinetics of Treg may possibly become the biomarker of ability of immune responses. Our data suggested that optimum imatinib exposure induce appropriate immune responses leading good prognosis, and excess imatinib exposure induce exhaust immune responses leading poor prognosis. Disclosures Nishikawa: Taihou Pharmaceuticals: Research Funding; Kyowa Hakko Kirin: Research Funding; Bristol-Myers Squibb: Research Funding, Speakers Bureau; Ono Pharmaceutical: Research Funding, Speakers Bureau; Chugai Pharmaceuticals: Research Funding, Speakers Bureau; Asahikasei Pharma: Research Funding; Sysmex: Research Funding; Daiichi Sankyo: Research Funding; Zennyaku: Research Funding. Takahashi:Otsuka Pharmaceutical: Research Funding, Speakers Bureau; Novartis Pharmaceuticals: Research Funding, Speakers Bureau; Chug Pharmaceuticals: Research Funding; Pfizer: Research Funding, Speakers Bureau; Asahi Kasei Pharma: Research Funding; Bristol-Myers Squibb: Speakers Bureau; Kyowa Hakko Kirin: Research Funding; Eisai Pharmaceuticals: Research Funding; Astellas Pharma: Research Funding; Ono Pharmaceutical: Research Funding.

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Lactobacillus plantarum surface-displayed ASFV (p54) with porcine IL-21 generally stimulates protective immune responses in mice

AMB Express ◽

10.1186/s13568-021-01275-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Xiao-Lei Chen ◽

Jun-Hong Wang ◽

Wei Zhao ◽

Chun-Wei Shi ◽

Kai-Dian Yang ◽

...

Keyword(s):

Flow Cytometry ◽

T Cells ◽

Immune Responses ◽

Fusion Protein ◽

Lactobacillus Plantarum ◽

Cd8 T Cells ◽

Classical Swine Fever ◽

Oral Vaccines ◽

Ifn Γ ◽

Mtt Assays

AbstractAfrican classical swine fever virus (ASFV) has spread seriously around the world and has dealt with a heavy blow to the pig breeding industry due to the lack of vaccines. In this study, we produced recombinant Lactobacillus plantarum (L. plantarum) expressing an ASFV p54 and porcine IL-21 (pIL-21) fusion protein and evaluated the immune effect of NC8-pSIP409-pgsA'-p54-pIL-21 in a mouse model. First, we verified that the ASFV p54 protein and p54-pIL-21 fusion protein were anchored on the surface of L. plantarum NC8 by flow cytometry, immunofluorescence and Western blotting. Then, the results were verified by flow cytometry, ELISA and MTT assays. Mouse-specific humoral immunity and mucosal and T cell-mediated immune responses were induced by recombinant L. plantarum. The results of feeding mice recombinant L. plantarum showed that the levels of serum IgG and mucosal secreted IgA (SIgA), the number of CD4 and CD8 T cells, and the expression of IFN-γ in CD4 and CD8 T cells increased significantly, and lymphocyte proliferation occurred under stimulation with the ASFV p54 protein. Our data lay a foundation for the development of oral vaccines against ASFV in the future.

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