Effect of Melan-Α/Μart-1-peptide vaccination plus IMP321 on antitumor immunity and clinical benefit in patients receiving autologous PBMCs after lymphodepletion.

e20011 Background: Immunotherapy offers great promise for cancer treatmet. Strong evidence supports adoptive cell transfer (ACT) and immunemodulation for regression of advanced melanoma. Few studies assessed the potential synergy between these two strategies. Methods: Twelve patients with metastatic melanoma received multiple Melan-A/Mart-1-peptide vaccinations with (n=6) or without (n=6) IMP321 (LAG-3Ig fusion protein) as an adjuvant in combination with lymphodepleting chemotherapy and ACT. All patients were selected on the basis of ex vivo detectable Melan-A-specific CD8 T cell responses and were immunized at day (D) 0, 8, 15, 22, 28, 52, and 74 post-reinfusion. Results: One-week after reinfusion of bulk autologous PBMCs, a significant expansion of Melan-A-specific CD8 T cells was measured in >83% (n=5) and <17% (n=1) of patients from the IMP321 and control groups, respectively (p=0.02). Compared to the control group, the mean fold increase of Melan-A-specific CD8 T cells was respectively >2-, >4-, and >6-fold higher in the IMP321 group at D15, D30, and D60 (p=0.02). A long-lasting Melan-A-specific CD8 T-cell response was significantly associated with IMP321 (p<0.001). A higher proportion of Melan-A-specific CD8 TEMRA (i.e., CD45RA+CCR7-CD127-) cells was observed in the IMP321 group at the peak of the response (p <0.002), whereas no significant difference was observed in the expression of co-inhibitory receptors (i.e., PD-1, 2B4, TIM3, CD160). IMP321 was associated with a significantly (p<0.04) reduced expansion of regulatory T cells (TREGS); we observed a negative correlation between the fold increase of Melan-A-specific CD8 T cells and the relative expansion of TREGS. Clinical benefit (assessed as CR, PR, and SD) was observed in none of the control patients vs 67% (4/6) of patients from the IMP321 group, (p=0.02). Conclusions: Vaccination with IMP321 as an adjuvant in combination with lymphodepleting chemotherapy and ACT provided clinical benefit and this was associated with a more robust and durable cellular antitumor immune response, supporting further development of IMP321 for future immunotherapeutic strategies. Clinical trial information: NCT00324623.

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Type I Interferons Regulate the Magnitude and Functionality of Mouse Polyomavirus-Specific CD8 T Cells in a Virus Strain-Dependent Manner

Journal of Virology ◽

10.1128/jvi.00199-16 ◽

2016 ◽

Vol 90 (10) ◽

pp. 5187-5199 ◽

Cited By ~ 7

Author(s):

Qingsong Qin ◽

Shwetank ◽

Elizabeth L. Frost ◽

Saumya Maru ◽

Aron E. Lukacher

Keyword(s):

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Cell Response ◽

Cd8 T Cell ◽

T Cell Response ◽

Single Amino Acid ◽

Type I ◽

Type I Ifns ◽

Vp1 Capsid Protein

ABSTRACTMouse polyomavirus (MPyV) is a ubiquitous persistent natural mouse pathogen. A glutamic acid (E)-to-glycine (G) difference at position 91 of the VP1 capsid protein shifts the profile of tumors induced by MPyV from an epithelial to a mesenchymal cell origin. Here we asked if this tropism difference affects the MPyV-specific CD8 T cell response, which controls MPyV infection and tumorigenesis. Infection by the laboratory MPyV strain RA (VP1-91G) or a strain A2 mutant with an E-to-G substitution at VP1 residue 91 [A2(91G)] generated a markedly smaller virus-specific CD8 T cell response than that induced by A2(VP1-91E) infection. Mutant A2(91G)-infected mice showed a higher frequency of memory precursor (CD127hiKLRG1lo) CD8 T cells and a higher recall response than those of A2-infected mice. Using T cell receptor (TCR)-transgenic CD8 T cells and immunization with peptide-pulsed dendritic cells, we found that early bystander inflammation associated with A2 infection contributed to recruitment of the larger MPyV-specific CD8 T cell response. Beta interferon (IFN-β) transcripts were induced early during A2 or A2(91G) infections. IFN-β inhibited replication of A2 and A2(91G)in vitro. Using mice lacking IFN-αβ receptors (IFNAR−/−), we showed that type I IFNs played a role in controlling MPyV replicationin vivobut differentially affected the magnitude and functionality of virus-specific CD8 T cells recruited by A2 and A2(91G) viral infections. These data indicate that type I IFNs are involved in protection against MPyV infection and that their effect on the antiviral CD8 T cell response depends on capsid-mediated tropism properties of the MPyV strain.IMPORTANCEIsolates of the human polyomavirus JC virus from patients with the frequently fatal demyelinating brain disease progressive multifocal leukoencephalopathy (PML) carry single amino acid substitutions in the domain of the VP1 capsid protein that binds the sialic acid moiety of glycoprotein/glycolipid receptors on host cells. These VP1 mutations may alter neural cell tropism or enable escape from neutralizing antibodies. Changes in host cell tropism can affect recruitment of virus-specific CD8 T cells. Using mouse polyomavirus, we demonstrate that a single amino acid difference in VP1 known to shift viral tropism profoundly affects the quantity and quality of the anti-polyomavirus CD8 T cell response and its differentiation into memory cells. These findings raise the possibility that CD8 T cell responses to infections by human polyomaviruses may be influenced by VP1 mutations involving domains that engage host cell receptors.

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Role of Thymic Output in Regulating CD8 T-Cell Homeostasis during Acute and Chronic Viral Infection

Journal of Virology ◽

10.1128/jvi.79.15.9419-9429.2005 ◽

2005 ◽

Vol 79 (15) ◽

pp. 9419-9429 ◽

Cited By ~ 29

Author(s):

Nicole E. Miller ◽

Jennifer R. Bonczyk ◽

Yumi Nakayama ◽

M. Suresh

Keyword(s):

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Cell Response ◽

Viral Infections ◽

T Cell Responses ◽

Cd8 T Cell ◽

T Cell Response ◽

Cell Responses ◽

Lcmv Infection

ABSTRACT Although it is well documented that CD8 T cells play a critical role in controlling chronic viral infections, the mechanisms underlying the regulation of CD8 T-cell responses are not well understood. Using the mouse model of an acute and chronic lymphocytic choriomeningitis virus (LCMV) infection, we have examined the relative importance of peripheral T cells and thymic emigrants in the elicitation and maintenance of CD8 T-cell responses. Virus-specific CD8 T-cell responses were compared between mice that were either sham thymectomized or thymectomized (Thx) at ∼6 weeks of age. In an acute LCMV infection, thymic deficiency did not affect either the primary expansion of CD8 T cells or the proliferative renewal and maintenance of virus-specific lymphoid and nonlymphoid memory CD8 T cells. Following a chronic LCMV infection, in Thx mice, although the initial expansion of CD8 T cells was normal, the contraction phase of the CD8 T-cell response was exaggerated, which led to a transient but striking CD8 T-cell deficit on day 30 postinfection. However, the virus-specific CD8 T-cell response in Thx mice rebounded quickly and was maintained at normal levels thereafter, which indicated that the peripheral T-cell repertoire is quite robust and capable of sustaining an effective CD8 T-cell response in the absence of thymic output during a chronic LCMV infection. Taken together, these findings should further our understanding of the regulation of CD8 T-cell homeostasis in acute and chronic viral infections and might have implications in the development of immunotherapy.

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596 Combining Bempegaldesleukin (CD122-preferential IL-2 pathway agonist) and NKTR-262 (TLR7/8 agonist) pairs local innate activation with systemic CD8+ T cell expansion to enhance anti-tumor immunity

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2021-sitc2021.596 ◽

2021 ◽

Vol 9 (Suppl 3) ◽

pp. A626-A626

Author(s):

Annah Rolig ◽

Daniel Rose ◽

Grace Helen McGee ◽

Saul Kivimae ◽

Werner Rubas ◽

...

Keyword(s):

T Cells ◽

Cell Death ◽

T Cell ◽

Immune Responses ◽

Cd8 T Cells ◽

Cd8 T Cell ◽

T Cell Response ◽

Cycle Phase ◽

Tumor Cell Death ◽

Specific Immunity

BackgroundTumor cell death caused by radiation therapy (RT) can trigger anti-tumor immune responses in part because dying cells release adjuvant factors that amplify and sustain DC and T cell responses. We previously demonstrated that bempegaldesleukin (BEMPEG:NKTR-214, a first-in-class CD122-preferential IL-2 pathway agonist), significantly enhanced the anti-tumor efficacy of RT through a T cell-dependent mechanism. Because RT can induce either immunogenic or tolerogenic cell death, depending on a multitude of factors (radiation dose, cell cycle phase, and tumor microenvironment), we hypothesized that providing a specific immunogenic adjuvant, like intratumoral NKTR-262, a novel toll-like receptor (TLR) 7/8 agonist, to the tumor site would further improve systemic tumor-specific immunity by promoting synergistic activation of local immunostimulatory innate immune responses. Therefore, we evaluated whether intratumoral NKTR-262, combined with systemic BEMPEG treatment would result in improved tumor-specific immunity and survival compared to BEMPEG combined with RT.MethodsTumor-bearing mice (CT26; EMT6) received BEMPEG (0.8 mg/kg; iv), RT (16 Gy x 1), and/or intratumoral NKTR-262 (0.5 mg/kg). Flow cytometry was used to evaluate CD4+ and CD8+ T cell activation status in the blood and tumor (7 days post-treatment). The contribution of specific immune subsets was determined by depletion of CD4+, CD8+, or NK cells. CD8+ T cell cytolytic activity was determined in vitro with an Incucyte assay. Data are representative of 1–2 independent experiments (n=5–14/group) and statistical significance was determined by 1-way ANOVA (p-value cut-off of 0.05).ResultsBEMPEG/NKTR-262 resulted in significantly improved survival compared to BEMPEG/RT. Both combination therapies were CD8+ T cell dependent. However, response to BEMPEG/NKTR-262 was characterized by a significant expansion of activated CD8+ T cells (GzmA+; Ki-67+; ICOS+; PD-1+) in the blood, which correlated with reduced tumor size (p<0.05). In the tumor, BEMPEG/NKTR-262 induced higher frequencies of GzmA+ CD8+ T cells exhibiting reduced expression of suppressive molecules (PD-1+, TIM-3+), compared to BEMPEG/RT. Additionally, CD8+ T cells isolated from BEMPEG/NKTR-262-treated tumors had greater cytolytic capacity than those from BEMPEG/RT-treated mice.ConclusionsCombining BEMPEG with NKTR-262 lead to a more robust expansion of activated CD8+ T cells compared to the BEMPEG/RT combination. Enhancement of the activated CD8+ T cell response in mice treated with NKTR-262 in combination with BEMPEG suggests that intratumoral TLR stimulation provides superior antigen presentation and costimulatory activity compared to RT. A clinical trial of BEMPEG/NKTR-262 for patients with metastatic solid tumors is in progress (NCT03435640).

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Mucosal CD8+ T cell responses induced by an MCMV based vaccine vector confer protection against influenza challenge

10.1101/494864 ◽

2018 ◽

Author(s):

Xiaoyan Zheng ◽

Jennifer Dora Oduro ◽

Julia Désirée Boehme ◽

Lisa Borkner ◽

Thomas Ebensen ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Cell Response ◽

Influenza A ◽

Clinical Medicine ◽

Cd8 T Cell ◽

T Cell Response ◽

Vaccine Vector ◽

Protective Capacity

Cytomegalovirus (CMV) is a ubiquitous β-herpesvirus that establishes life-long latent infection in a high percentage of the population worldwide. CMV induces the strongest and most durable CD8+ T cell response known in human clinical medicine. Due to its unique properties, the virus represents a promising candidate vaccine vector for the induction of persistent cellular immunity. To take advantage of this, we constructed a recombinant murine CMV (MCMV) expressing an MHC-I restricted epitope from influenza A virus (IAV) H1N1 within the immediate early 2 (ie2) gene. Only mice that were immunized intranasally (i.n.) were capable of controlling IAV infection, despite the greater potency of the intraperitoneally (i.p.) vaccination in inducing a systemic IAV-specific CD8+ T cell response. The protective capacity of the i.n. immunization was associated with its ability to induce IAV-specific tissue-resident memory CD8+ T (CD8TRM) cells in the lungs. Our data demonstrate that the protective effect exerted by the i.n. immunization was critically mediated by antigen-specific CD8+ T cells. CD8TRM cells promoted the induction of IFNγ and chemokines that facilitate the recruitment of antigen-specific CD8+ T cells to the lungs. Overall, our results showed that locally applied MCMV vectors could induce mucosal immunity at sites of entry, providing superior immune protection against respiratory infections.

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Chimeric Yellow Fever/Dengue Virus as a Candidate Dengue Vaccine: Quantitation of the Dengue Virus-Specific CD8 T-Cell Response

Journal of Virology ◽

10.1128/jvi.74.17.8094-8101.2000 ◽

2000 ◽

Vol 74 (17) ◽

pp. 8094-8101 ◽

Cited By ~ 77

Author(s):

Robbert G. van der Most ◽

Kaja Murali-Krishna ◽

Rafi Ahmed ◽

James H. Strauss

Keyword(s):

T Cells ◽

T Cell ◽

Dengue Virus ◽

Yellow Fever ◽

Cd8 T Cells ◽

Cell Response ◽

Protective Efficacy ◽

Cd8 T Cell ◽

T Cell Response ◽

E Proteins

ABSTRACT We have constructed a chimeric yellow fever/dengue (YF/DEN) virus, which expresses the premembrane (prM) and envelope (E) genes from DEN type 2 (DEN-2) virus in a YF virus (YFV-17D) genetic background. Immunization of BALB/c mice with this chimeric virus induced a CD8 T-cell response specific for the DEN-2 virus prM and E proteins. This response protected YF/DEN virus-immunized mice against lethal dengue encephalitis. Control mice immunized with the parental YFV-17D were not protected against DEN-2 virus challenge, indicating that protection was mediated by the DEN-2 virus prM- and E-specific immune responses. YF/DEN vaccine-primed CD8 T cells expanded and were efficiently recruited into the central nervous systems of DEN-2 virus challenged mice. At 5 days after challenge, 3 to 4% of CD8 T cells in the spleen were specific for the prM and E proteins, and 34% of CD8 T cells in the central nervous system recognized these proteins. Depletion of either CD4 or CD8 T cells, or both, strongly reduced the protective efficacy of the YF/DEN virus, stressing the key role of the antiviral T-cell response.

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T Cell Recognition of HCMV: Pan-Genome Analysis of Immunogenic Open-Reading Frames.

Blood ◽

10.1182/blood.v104.11.606.606 ◽

2004 ◽

Vol 104 (11) ◽

pp. 606-606 ◽

Cited By ~ 1

Author(s):

Louis J. Picker ◽

Andrew W. Sylwester ◽

Bridget L. Mitchell ◽

Cara Taormina ◽

Christian Pelte ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Peripheral Blood ◽

Cell Response ◽

Cd8 T Cell ◽

Cross Reactivity ◽

T Cell Response ◽

Cd4 T Cell ◽

Cell Responses

Abstract Human Cytomegalovirus (HCMV) is among the largest and most complex of known viruses with 150–200nm virions enclosing a double stranded 230kb DNA genome capable of coding for >200 proteins. HCMV infection is life-long, and for the vast majority of immune competent individuals clinically benign. Disease occurs almost exclusively in the setting of immune deficiency, suggesting that the stable host-parasite relationship that characterizes these infections is the result of an evolutionarily “negotiated” balance between viral mechanisms of pathogenesis and the host immune response. In keeping with, and perhaps because of this balance, the human CD4+ T cell response to whole HCMV viral lysates is enormous, with median peripheral blood frequencies of HCMV-specific cells ~5–10 fold higher than for analogous preparations of other common viruses. Although certain HCMV ORFs have been identified as targets of either the CD4+ or CD8+ T cell response, the specificities comprising the CD4+ T cell response, and both the total frequencies and component parts of the CD8+ T cell response are unknown. Here, we used cytokine flow cytometry and ~14,000 overlapping 15mer peptides comprising all 213 HCMV ORFs encoding proteins >100 amino acids in length to precisely define the total CD4+ and CD8+ HCMV-specific T cell responses and the HCMV ORFs responsible for these responses in 33 HCMV-seropositive, HLA-disparate donors. An additional 9 HCMV seronegative donors were similarly examined to define the extent to which non-HCMV responses cross-react with HCMV-encoded epitopes. We found that when totaled, the median frequencies of HCMV-specific CD4+ and CD8+ T cells in the peripheral blood of the seropositive subjects were 4.0% and 4.5% for the total CD4+ or CD8+ T cell populations, respectively (which corresponds to 9.1% and 10.5% of the memory populations, respectively). The HCMV-specific CD4+ and CD8+ T cell responses included a median 12 and 7 different ORFs, respectively, and all told, 73 HCMV ORFs were identified as targets for both CD4+ and CD8+ T cells, 26 ORFs as targets for CD8+ T cells alone, and 43 ORFS as targets for CD4+ T cells alone. UL55, UL83, UL86, UL99, and UL122 were the HCMV ORFs most commonly recognized by CD4+ T cells; UL123, UL83, UL48, UL122 and UL28 were the HCMV ORFs most commonly recognized by CD8+ T cells. The relationship between immunogenicity and 1) HLA haplotype and 2) ORF expression and function will be discussed. HCMV-seronegative individuals were non-reactive with the vast majority of HCMV peptides. Only 7 potentially cross-reactive responses were identified (all by CD8+ T cells) to 3 ORFs (US32, US29 and UL116) out of a total of almost 4,000 potential responses, suggesting fortuitous cross-reactivity with HCMV epitopes is uncommon. These data provide the first glimpse of the total human T cell response to a complex infectious agent, and will provide insight into the rules governing immunodominance and cross-reactivity in complex viral infections of humans.

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The Response to Repeated Vaccination with PR1 and WT1 Peptides Admixed in Montanide Adjuvant Is Transient and Fails to Induce Sustained Anti-Leukemia Responses in Patients with Myeloid Malignancies.

Blood ◽

10.1182/blood.v114.22.4096.4096 ◽

2009 ◽

Vol 114 (22) ◽

pp. 4096-4096

Author(s):

Katayoun Rezvani ◽

Agnes S. M. Yong ◽

Stephan Mielke ◽

Behnam Jafarpour ◽

Bipin N. Savani ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Cell Response ◽

T Cell Responses ◽

Cd8 T Cell ◽

T Cell Response ◽

Gm Csf ◽

Cell Responses ◽

Ifn Γ

Abstract Abstract 4096 Poster Board III-1031 We previously demonstrated the immunogenicity of a combined vaccine approach employing two leukemia-associated antigenic peptides, PR1 and WT1 (Rezvani Blood 2008). Eight patients with myeloid malignancies received one subcutaneous 0.3 mg and 0.5 mg dose each of PR1 and WT1 vaccines in Montanide adjuvant, with 100 μg of granulocyte-macrophage colony-stimulating factor (GM-CSF). CD8+ T-cell responses against PR1 or WT1 were detected in all patients as early as 1 week post-vaccination. However, responses were only sustained for 3-4 weeks. The emergence of PR1 or WT1-specific CD8+ T-cells was associated with a significant but transient reduction in minimal residual disease (MRD) as assessed by WT1 expression, suggesting a vaccine-induced anti-leukemia response. Conversely, loss of response was associated with reappearance of WT1 transcripts. We hypothesized that maintenance of sustained or at least repetitive responses may require frequent boost injections. We therefore initiated a phase 2 study of repeated vaccination with PR1 and WT1 peptides in patients with myeloid malignancies. Five patients with acute myeloid leukemia (AML) and 2 patients with myelodysplastic syndrome (MDS) were recruited to receive 6 injections at 2 week intervals of PR1 and WT1 in Montanide adjuvant, with GM-CSF as previously described. Six of 7 patients completed 6 courses of vaccination and follow-up as per protocol, to monitor toxicity and immunological responses. Responses to PR1 or WT1 vaccine were detected in all patients after only 1 dose of vaccine. However, additional boosting did not further increase the frequency of PR1 or WT1-specific CD8+ T-cell response. In 4/6 patients the vaccine-induced T-cell response was lost after the fourth dose and in all patients after the sixth dose of vaccine. To determine the functional avidity of the vaccine-induced CD8+ T-cell response, the response of CD8+ T-cells to stimulation with 2 concentrations of PR1 and WT1 peptides (0.1 and 10 μM) was measured by IC-IFN-γ staining. Vaccination led to preferential expansion of low avidity PR1 and WT1 specific CD8+ T-cell responses. Three patients (patients 4, 6 and 7) returned 3 months following the 6th dose of PR1 and WT1 peptide injections to receive a booster vaccine. Prior to vaccination we could not detect the presence of PR1 and WT1 specific CD8+ T-cells by direct ex-vivo tetramer and IC-IFN-γ assay or with 1-week cultured IFN-γ ELISPOT assay, suggesting that vaccination with PR1 and WT1 peptides in Montanide adjuvant does not induce memory CD8+ T-cell responses. This observation is in keeping with recent work in a murine model where the injection of minimal MHC class I binding peptides derived from self-antigens mixed with IFA adjuvant resulted in a transient effector CD8+ T cell response with subsequent deletion of these T cells and failure to induce CD8+ T cell memory (Bijker J Immunol 2007). This observation can be partly explained by the slow release of vaccine peptides from the IFA depot without systemic danger signals, leading to presentation of antigen in non-inflammatory lymph nodes by non-professional antigen presenting cells (APCs). An alternative explanation for the transient vaccine-induced immune response may be the lack of CD4+ T cell help. In summary these data support the immunogenicity of PR1 and WT1 peptide vaccines. However new approaches will be needed to induce long-term memory responses against leukemia antigens. To avoid tolerance induction we plan to eliminate Montanide adjuvant and use GM-CSF alone. Supported by observations that the in vivo survival of CD8+ T-effector cells against viral antigens are improved by CD4+ helper cells, we are currently attempting to induce long-lasting CD8+ T-cell responses to antigen by inducing CD8+ and CD4+ T-cell responses against class I and II epitopes of WT1 and PR1. Disclosures: No relevant conflicts of interest to declare.

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In Vivo Model to Evaluate Loss of Liver-Derived Factor IX Expression Caused by AAV Capsid-Specific CD8+ T Cells

Blood ◽

10.1182/blood.v120.21.2046.2046 ◽

2012 ◽

Vol 120 (21) ◽

pp. 2046-2046

Author(s):

David M Markusic ◽

Ashley T Martino ◽

Federico Mingozzi ◽

Katherine A. High ◽

Roland W Herzog

Keyword(s):

T Cells ◽

T Cell ◽

Gene Transfer ◽

Cd8 T Cells ◽

Cd8 T Cell ◽

T Cell Response ◽

Factor Ix ◽

In Vivo Model ◽

Mhc I

Abstract Abstract 2046 Long-term partial correction of severe hemophilia B following peripheral vein delivery of an AAV8-factor IX vector in human subjects has recently been reported. However, the two patients in the high-dose cohort experienced a rise in liver transaminases and drop in circulating F.IX levels that was halted with steroid treatment. In both the AAV8 and in an earlier AAV2-based trial, a dose of 2×1012 vg/kg seemed above a threshold for the activation of capsid specific memory CD8+ cytotoxic T lymphocytes (CTL). Therefore, reaching a target of > 5% sustained F.IX level (for a change to mild disease) is currently limited by activation of T cell immunity against capsid. New clinical trials are in the pipeline with AAV8 vectors expressing hyperactive F.IX variants that provide therapeutic F.IX expression at lower vector doses, with a goal of avoiding activation of CD8+ T cell memory response. Lack of a preclinical model to study CTL-mediated loss of AAV gene therapy has hampered efforts at clinical development. Neither mice nor non-human primates have recapitulated the human experience, making it difficult to evaluate, prior to clinical trial design, the effect of the serotype, vector dose, and other parameters of the protocol on targeting by capsid-specific T cells. To solve this problem, we have recently developed a murine model, in which male BALB/c RAG −/− mice receive hepatic AAV gene transfer followed by intravenous administration of in vitro expanded strain-matched capsid-specific CD8+ T cells (specific to an MHC I capsid epitope conserved between AAV2 and AAV8 serotypes shared between BALB/c mice and humans expressing the B*0702 molecule). In this model, AAV2-F.IX transduced mice showed a rise in liver enzymes, loss of circulating F.IX, and loss of F.IX expressing hepatocytes, following adoptive transfer of the CTL one day but not 7 or 14 days after gene transfer. CD8+ T cell infiltrates were observed 7 days following adoptive transfer and were absent at 28 days, suggesting a small window for optimal AAV2 capsid antigen presentation in the liver. Additionally, mice were protected from capsid specific CD8+ T cells when treated with the proteasome inhibitor bortezomib, which impairs the generation of peptide epitopes for MHC I antigen presentation. We next tested in our model AAV8 vectors, which in mice show superior tropism for liver. Published pre-clinical data by others suggested lack of capsid-specific CD8+ cell activation with this serotype. While this was not borne out in a clinical trial, the onset of T cell responses and of transaminitis in humans appeared to be delayed for AAV8 vector (8–9 weeks after gene transfer) compared to AAV2 (3–4 weeks). In comparison to AAV2, CD8+ T cell transfer in AAV8 injected mice had a milder impact on circulating F.IX levels (<50% loss of expression as opposed to 4-fold loss with AAV2), and CD8+ T cell infiltrates were largely absent at day 7. In two different experiments, 25–40% of F.IX expressing hepatocytes were lost compared to AAV8-F.IX transduced mice that received no or control CD8+ T cells. However, when the T cells were transferred 7 or 14 days after AAV8 administration, a more robust loss of systemic F.IX expression was observed (3- to 5-fold), with a 45% and 32% reduction in F.IX expressing hepatocytes, respectively (Fig 1 A-C). CD8+ T cell infiltrates were prevalent by day 42 in the livers of these animals. Together, these data suggest that optimal AAV8 capsid presentation in the murine liver occurs between days 28 and 42 following gene transfer. This delay in targeting of AAV8 transduced murine liver is consistent with the delay observed between the AAV2 and AAV8 F.IX clinical trials. This murine model should be useful to (1) evaluate novel AAV serotypes and capsid variants, (2) test the effect of the vector dose, (3) test the effect of pharmacological modulation on capsid presentation and targeting by capsid-specific CTL, and (4) provide guidance for the timing for immune suppression. Figure 1. In vivo model for AAV8 capsid specific CD8 T cell response following AAV8 hF.IX liver gene transfer. (A) hF.IX levels (B) % hF.IX hepatocytes 42 days post vector (C) liver sections stained for hF.IX (red) and CD8 (green) 42 days post vector. Figure 1. In vivo model for AAV8 capsid specific CD8 T cell response following AAV8 hF.IX liver gene transfer. (A) hF.IX levels (B) % hF.IX hepatocytes 42 days post vector (C) liver sections stained for hF.IX (red) and CD8 (green) 42 days post vector. Disclosures: High: Amsterdam Molecular Therapeutics: ; Baxter Healthcare: Consultancy; Biogen Idec: Consultancy; bluebird bio, Inc.: Membership on an entity's Board of Directors or advisory committees; Genzyme, Inc.: Membership on an entity's Board of Directors or advisory committees; Novo Nordisk: ; Sangamo Biosciences: ; Shire Pharmaceuticals: Consultancy. Herzog:Genzyme Corp.: Royalties, AAV-FIX technology, Royalties, AAV-FIX technology Patents & Royalties.

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Recovery of CMV-Specific T Cells Following Alternative Donor Allogeneic Transplant with Post-Transplant Cyclophosphamide

Blood ◽

10.1182/blood.v126.23.5462.5462 ◽

2015 ◽

Vol 126 (23) ◽

pp. 5462-5462

Author(s):

Ayman Saad ◽

Samantha B Langford ◽

Shin Mineishi ◽

Lawrence S. Lamb

Keyword(s):

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Cell Response ◽

Cd8 T Cell ◽

T Cell Response ◽

Cell Recovery ◽

Post Transplant ◽

Increased Risk ◽

Cmv Reactivation

Abstract Background: Post-transplant cyclophosphamide (PTCy) is increasingly used for GVHD prophylaxis after allogeneic hematopoietic stem cell transplantation (HCT) using alternative donors. However, immune reconstitution can be delayed posing an increased risk for CMV reactivation. We evaluated the outcomes of patients who received HCT-apheresis products comparing the impact of PTCy on lymphocyte recovery, CMV reactivation and CMV-specific CD8+ T cell recovery following haplo-identical (HAPLO), matched unrelated donor (MUD), and mismatched unrelated donor (mMUD) grafts vs. with conventional matched related donor (MRD) graft recipients. Methods: We examined 26 patients (median age, 49 years; range, 20-72 years) with advanced hematologic malignancies; n=5 (HAPLO); 6 (MRD); 15 (MUD). All patients received myeloablative conditioning regimens that was either busulfan- or total body irradiation (TBI)-based. PTCy (50 mg/kg/day) was administered on days +3 and +4 following HAPLO and on day +3 following MUD/mMUD transplant. Peripheral blood lymphocyte reconstitution and frequency of circulating CMV-directed CD8+ T cells was assessed (day ± 10 days) on post-transplant days +30, +60, and +90. Circulating anti-CMV T cell frequency was assessed using a phycoerythrin-tagged MHC dextramer against HLA-specific CMV pp65, IE-1, or pp50 peptides (Immudex; Copenhagen, DK) in combination with Tru-Count¨ tubes and fluorescent-labeled monoclonal antibodies against CD3, CD8, CD4, CD16/56, and CD19 (BD Biosciences; San Jose, CA). Anti-CMV CD8+ T cell immunity was defined as a CMV-dextramer (CMV/DEX) positive count of ≥7cells/ml. CMV reactivation was defined as a serologic titer of >500IU/mL. All patients with CMV reactivation received ganciclovir therapy until CMV titer became negative. Results: Day +30 total T cell recovery was significantly faster in MRD than CY-treated recipients (p=0.015) due principally to more robust CD8+ T cell recovery. CD4 T cell recovery remained below normal range in all groups through day +100. NK cells recovered to normal numbers at day +28 in all groups. Neither PTCy nor donor source significantly impacted the percentage of patients that recovered anti-CMV CD8+ T cells at each time interval (p = 0.8232). Excluding donors (D) and recipients (R) that were both negative, CMV/DEX+ T cells recovery was >7/mL in 4/5 MRD, 7/14 MUD, and 3/5 HAPLO by day +100. Among MRD recipients either D+ or R+ (n=5), 2 patients showed CMV reactivation within 40 days of transplant that was associated with <7 CMV/DEX+ T cells on day +30. Subsequent high (>90/mL) CMV/DEX T cell response in one patient shortened the duration of viremia to 10 days (vs. 16 days with poor responder) and 3 patients showed no CMV reactivation and a high CMV/DEX+ T cell response by day +60. For MUD CMV D+ and/or R+ recipients (n=14), 3 showed CMV reactivation within 50 days of transplant. All 3 patients had suboptimal CMV/DEX T cell response on day +30. Robust CMV/DEX+ T cell response on day +60 predicted shorter duration of viremia (20 days vs. average of 32 days). For HAPLO CMV D+ and/or R+ (n=5) recipients, 4 experienced CMV reactivation within 50 days of transplant. All patients had a <7 CMV/DEX+ T cells/mL +30. Robust CMV/DEX+ T cell response by day +60 was associated with shorter duration of viremia (range 7-21 days), while one patient with <7/mL CMV/DEX+ T cells had continued CMV viremia for 36 days. Conclusion: In this preliminary analysis, neither PTCy nor donor source significantly impacted the percentage of patients that recovered anti-CMV CD8+ T cells at each time interval. A weak CMV/DEX+ response (<7 cells/mL) on day +30 was consistent with increased risk of CMV reactivation (viremia) in all groups. A CMV/DEX+ T cell count ≥7 cells/mL was not immediately protective against CMV reactivation, but higher counts were associated with a shortened duration of viremia while on antiviral therapy. Conversely, subnormal counts were associated with a longer duration of viremia. This interim analysis suggests that CMV/DEX+ T cell enumeration is a useful biologic correlate for determining clinical response to antiviral therapy, and that donor-derived CMV specific T cell immunity is not further compromised with following PTCy in alternative donor HCT. Disclosures No relevant conflicts of interest to declare.

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