Comprehensive landscape of neutralizing antibody and cell-mediated response elicited by the 1/5 fractional dose of 17DD-YF primary vaccination in adults.

The present study aimed at evaluating the YF-specific neutralizing antibody profile besides a multiparametric analysis of phenotypic/functional features of cell-mediated response elicited by the 1/5 fractional dose of 17DD-YF vaccine, administered as a single subcutaneous injection. The immunological parameters of each volunteer was monitored at two time points, referred as: before (Day 0) [Non-Vaccinated, NV(D0)] and after vaccination (Day 30-45) [Primary Vaccinees, PV(D30-45)]. Data demonstrated high levels of neutralizing antibodies for PV(D30-45) leading to a seropositivity rate of 93%. A broad increase of systemic soluble mediators with a mixed profile was also observed for PV(D30-45), with IFN-γ and TNF-α presenting the highest baseline fold changes. Integrative network mapping of soluble mediators showed increased correlation numbers in PV(D30-45) as compared to NV(D0) (532vs398). Moreover, PV(D30-45) exhibited increased levels of Terminal Effector (CD45RA+CCR7-) CD4+ and CD8+ T-cells and Non-Classical memory B-cells (IgD+CD27+). Dimensionality reduction of Mass Cytometry data further support these findings. A polyfunctional cytokine profile (TNF-α/IFN-γ/IL-10/IL-17/IL-2) of T and B-cells was observed upon in vitro antigen recall. Mapping and kinetics timeline of soluble mediator signatures for PV(D30-45) further confirmed the polyfunctional profile upon long-term in vitro culture, mediated by increased levels of IFN-γ and TNF-α along with decreased production of IL-10. These findings suggest novel insights of correlates of protection elicited by the 1/5 fractional dose of 17DD-YF vaccine.

Immune determinants of CAR-T cell expansion in solid tumor patients receiving GD2 CAR-T cell therapy.

Chimeric antigen receptor T cells (CAR-Ts) have remarkable efficacy in liquid tumors, but limited responses in solid tumors. We conducted a Phase I trial (NCT02107963) of GD2 CAR-Ts (GD2-CAR.OX40.28.z.iC9), demonstrating feasibility and safety of administration in children and young adults with osteosarcoma and neuroblastoma. Since CAR-T efficacy requires adequate CAR-T expansion, patients were grouped into good or poor expanders across dose levels. Patient samples were evaluated by multi-dimensional proteomic, transcriptomic, and epigenetic analyses. T cell assessments identified naive T cells in pre-treatment apheresis associated with good expansion, and exhausted T cells in CAR-T products with poor expansion. Myeloid cell assessment identified CXCR3+ monocytes in pre-treatment apheresis associated with good expansion. Longitudinal analysis of post-treatment samples identified increased CXCR3- classical monocytes in all groups as CAR-T numbers waned. Together, our data uncover mediators of CAR-T biology and correlates of expansion that could be utilized to advance immunotherapies for solid tumor patients.

Intrinsic suppression of type I interferon production underlies the therapeutic efficacy of IL-15-producing natural killer cells in B-cell acute lymphoblastic leukemia.

BACKGROUND: Type I interferons (IFN-Is), secreted by hematopoietic cells, drive immune surveillance of solid tumors. However, the mechanisms of suppression of IFN-I-driven immune responses in hematopoietic malignancies including B-cell acute lymphoblastic leukemia (B-ALL) are unknown. METHODS: Using high-dimensional cytometry, we delineate the defects in IFN-I production and IFN-I-driven immune responses in high-grade primary human and mouse B-ALLs. We develop natural killer (NK) cells as therapies to counter the intrinsic suppression of IFN-I production in B-ALL. RESULTS: We find that high expression of IFN-I signaling genes predicts favorable clinical outcome in patients with B-ALL, underscoring the importance of the IFN-I pathway in this malignancy. We show that human and mouse B-ALL microenvironments harbor an intrinsic defect in paracrine (plasmacytoid dendritic cell) and/or autocrine (B-cell) IFN-I production and IFN-I-driven immune responses. Reduced IFN-I production is sufficient for suppressing the immune system and promoting leukemia development in mice prone to MYC-driven B-ALL. Among anti-leukemia immune subsets, suppression of IFN-I production most markedly lowers the transcription of IL-15 and reduces NK-cell number and effector maturation in B-ALL microenvironments. Adoptive transfer of healthy NK cells significantly prolongs survival of overt ALL-bearing transgenic mice. Administration of IFN-Is to B-ALL-prone mice reduces leukemia progression and increases the frequencies of total NK and NK-cell effectors in circulation. Ex vivo treatment of malignant and non-malignant immune cells in primary mouse B-ALL microenvironments with IFN-Is fully restores proximal IFN-I signaling and partially restores IL-15 production. In B-ALL patients, the suppression of IL-15 is the most severe in difficult-to-treat subtypes with MYC overexpression. MYC overexpression promotes sensitivity of B-ALL to NK cell-mediated killing. To counter the suppressed IFN-I-induced IL-15 production in MYChigh human B-ALL, we CRISPRa-engineered a novel human NK-cell line that secretes IL-15. CRISPRa IL-15-secreting human NK cells kill high-grade human B-ALL in vitro and block leukemia progression in vivo more effectively than NK cells that do not produce IL-15. CONCLUSION: We find that restoration of the intrinsically suppressed IFN-I production in B-ALL underlies the therapeutic efficacy of IL-15-producing NK cells and that such NK cells represent an attractive therapeutic solution for the problem of drugging MYC in high-grade B-ALL.

IL-7 expands lymphocyte populations and enhances immune responses to sipuleucel-T in patients with metastatic castration-resistant prostate cancer (mCRPC).

BACKGROUND: Sipuleucel-T (sip-T) is a Food and Drug Administration (FDA)-approved autologous cellular immunotherapy for metastatic castration-resistant prostate cancer (mCRPC). We hypothesized that combining sip-T with interleukin (IL)-7, a homeostatic cytokine that enhances both B and T cell development and proliferation, would augment and prolong antigen-specific immune responses against both PA2024 (the immunogen for sip-T) and prostatic acid phosphatase (PAP). METHODS: Fifty-four patients with mCRPC treated with sip-T were subsequently enrolled and randomized 1:1 into observation (n=26) or IL-7 (n=28) arms of a phase II clinical trial (NCT01881867). Recombinant human (rh) IL-7 (CYT107) was given weekly×4. Immune responses were evaluated using flow cytometry, mass cytometry (CyTOF), interferon (IFN)-γ ELISpot, 3H-thymidine incorporation, and ELISA. RESULTS: Treatment with rhIL-7 was well tolerated. For the rhIL-7-treated, but not observation group, statistically significant lymphocyte subset expansion was found, with 2.3-2.6-fold increases in CD4+T, CD8+T, and CD56bright NK cells at week 6 compared with baseline. No significant differences in PA2024 or PAP-specific T cell responses measured by IFN-γ ELISpot assay were found between rhIL-7 and observation groups. However, antigen-specific T cell proliferative responses and humoral IgG and IgG/IgM responses significantly increased over time in the rhIL-7-treated group only. CyTOF analyses revealed pleiotropic effects of rhIL-7 on lymphocyte subsets, including increases in CD137 and intracellular IL-2 and IFN-γ expression. While not powered to detect clinical outcomes, we found that 31% of patients in the rhIL-7 group had prostate specific antigen (PSA) doubling times of >6 months, compared with 14% in the observation group. CONCLUSIONS: Treatment with rhIL-7 led to a significant expansion of CD4+ and CD8+ T cells, and CD56bright natural killer (NK) cells compared with observation after treatment with sip-T. The rhIL-7 treatment also led to improved antigen-specific humoral and T cell proliferative responses over time as well as to increased expression of activation markers and beneficial cytokines. This is the first study to evaluate the use of rhIL-7 after sip-T in patients with mCRPC and demonstrates encouraging results for combination approaches to augment beneficial immune responses.

Immune Profiling Mass Cytometry Assay Harmonization: Multicenter Experience from CIMAC-CIDC.

PURPOSE: The Cancer Immune Monitoring and Analysis Centers - Cancer Immunologic Data Commons (CIMAC-CIDC) Network is supported by the NCI to identify biomarkers of response to cancer immunotherapies across clinical trials using state-of-the-art assays. A primary platform for CIMAC-CIDC studies is cytometry by time of flight (CyTOF), performed at all CIMAC laboratories. To ensure the ability to generate comparable CyTOF data across labs, a multistep cross-site harmonization effort was undertaken. EXPERIMENTAL DESIGN: We first harmonized standard operating procedures (SOPs) across the CIMAC sites. Because of a new acquisition protocol comparing original narrow- or new wide-bore injector introduced by the vendor (Fluidigm), we also tested this protocol across sites before finalizing the harmonized SOP. We then performed cross-site assay harmonization experiments using five shared cryopreserved and one lyophilized internal control peripheral blood mononuclear cell (PBMC) with a shared lyophilized antibody cocktail consisting of 14 isotype-tagged antibodies previously validated, plus additional liquid antibodies. These reagents and samples were distributed to the CIMAC sites and the data were centrally analyzed by manual gating and automated methods (Astrolabe). RESULTS: Average coefficients of variation (CV) across sites for each cell population were reported and compared with a previous multisite CyTOF study. We reached an intersite CV of under 20% for most cell subsets, very similar to a previously published study. CONCLUSIONS: These results establish the ability to reproduce CyTOF data across sites in multicenter clinical trials, and also highlight the importance of quality control procedures, such as the use of spike-in control samples, for tracking variability in this assay.

Activated natural killer cells predict poor clinical prognosis in high-risk B- and T-cell acute lymphoblastic leukemia.

B- and T-cell acute lymphoblastic leukemia (B/T-ALL) may be refractory or recur after therapy by suppressing host anticancer immune surveillance mediated specifically by natural killer (NK) cells. We delineated the phenotypic and functional defects in NK cells from high-risk patients with B/T-ALL using mass cytometry, flow cytometry, and in silico cytometry, with the goal of further elucidating the role of NK cells in sustaining acute lymphoblastic leukemia (ALL) regression. We found that, compared with their normal counterparts, NK cells from patients with B/T-ALL are less cytotoxic but exhibit an activated signature that is characterized by high CD56, high CD69, production of activated NK cell-origin cytokines, and calcium (Ca2+) signaling. We demonstrated that defective maturation of NK cells into cytotoxic effectors prevents NK cells from ALL from lysing NK cell-sensitive targets as efficiently as do normal NK cells. Additionally, we showed that NK cells in ALL are exhausted, which is likely caused by their chronic activation. We found that increased frequencies of activated cytokine-producing NK cells are associated with increased disease severity and independently predict poor clinical outcome in patients with ALL. Our studies highlight the benefits of developing NK cell profiling as a diagnostic tool to predict clinical outcome in patients with ALL and underscore the clinical potential of allogeneic NK cell infusions to prevent ALL recurrence.

CD81 is a novel immunotherapeutic target for B cell lymphoma.

The tetraspanin CD81 was initially discovered by screening mAbs elicited against a human B cell lymphoma for their direct antiproliferative effects. We now show that 5A6, one of the mAbs that target CD81, has therapeutic potential. This antibody inhibits the growth of B cell lymphoma in a xenograft model as effectively as rituximab, which is a standard treatment for B cell lymphoma. Importantly, unlike rituximab, which depletes normal as well as malignant B cells, 5A6 selectively kills human lymphoma cells from fresh biopsy specimens while sparing the normal lymphoid cells in the tumor microenvironment. The 5A6 antibody showed a good safety profile when administered to a mouse transgenic for human CD81. Taken together, these data provide the rationale for the development of the 5A6 mAb and its humanized derivatives as a novel treatment against B cell lymphoma.

IL-33-expanded human Vγ9Vδ2 T cells have anti-lymphoma effect in a mouse tumor model.

From several years, the anticancer effects of Vγ9 T lymphocytes make these cells good candidates for cancer immunotherapies. However, the proved efficacy of γδ Τ cell-based cancer immunotherapies in some clinical trials was minimized due to the inherent toxicity of IL-2, which is essential for the combination therapy with Phosphoantigen (PAg). Recently, we showed that IL-33, a γ chain receptor-independent cytokine, was able to induce the in vitro proliferation of PAg-activated Vγ9 T cells, which were fully functional expressing IFN-γ and TNF-α and showing in vitro anti-tumor cytotoxicity. We proposed IL-33 as an alternative to IL-2 for Vγ9 T cell-based cancer immunotherapies, and have therefore evaluated the efficacy of this cytokine in preclinical investigations. This study shows that human Vγ9 T cells are able to proliferate in a mouse model with the combination of PAg and rhIL-33, and that IL-33-expanded Vγ9 T cells can prevent tumor growth in a mouse lymphoma model.

CD81 as a tumor target.

CD81 participates in a variety of important cellular processes such as membrane organization, protein trafficking, cellular fusion and cell-cell interactions. In the immune system, CD81 regulates immune synapse, receptor clustering and signaling; it also mediates adaptive and innate immune suppression. CD81 is a gateway in hepatocytes for pathogens such as hepatitis C virus and Plasmodium; it also confers susceptibility to Listeria infection. These diverse biological roles are due to the tendency of CD81 to associate with other tetraspanins and with cell-specific partner proteins, which provide the cells with a signaling platform. CD81 has also been shown to regulate cell migration and invasion, and has therefore been implicated in cancer progression. Indeed, we have recently shown that CD81 contributes to tumor growth and metastasis. CD81 is expressed in most types of cancer, including breast, lung, prostate, melanoma, brain cancer and lymphoma, and the overexpression or down-regulation of this molecule has been correlated with either good or bad prognosis. Here, we discuss the role of CD81 in cancer and its potential therapeutic use as a tumor target.

TCRVγ9 γδ T Cell Response to IL-33: A CD4 T Cell-Dependent Mechanism.

The availability of specific stimuli to induce the anticancer cytotoxicity of human TCRVγ9-expressing T lymphocytes has allowed the development of γδ T cell-based cancer immunotherapies. However, the stringent dependence of such strategies on the inherently toxic IL-2 has raised safety concerns for patients, justifying a search for alternative methods for inducing γδ T cell stimulation. IL-33 is a γ-chain receptor-independent cytokine of the IL-1 superfamily that is expressed by endothelial cells from a tumor microenvironment and can sustain Th1 and Th2 immune responses. Therefore, we investigated its ability to support the stimulation of human TCRVγ9(+) γδ T cells. In this study, we report that IL-33 efficiently sustained the in vitro activation of Vγ9 T lymphocytes by synthetic phosphoantigens, zoledronate, and a BTN3A1 Ab in the absence of an exogenous supply of IL-2. IL-33 was as potent as IL-2 in allowing the proliferative amplification of Vγ9 T cells isolated from PBMC following activation by the synthetic phosphoantigen bromohydrin pyrophosphate. IL-33 also induced an identical maturation into TNF-α- and IFN-γ-producing Th1 effector memory cells, and IL-33-stimulated cells showed an equivalent cytotoxicity for various tumor cells in vitro. Finally, we found that the bioactivity of IL-33 on the Vγ9 T cell was indirectly mediated through contact with CD4 T cells and IL-2 production by CD4 T cells and Vγ9 T cells themselves. These data posit IL-33 as an alternative to IL-2 for Vγ9 T cell-based cancer immunotherapies.

Phosphoantigens and butyrophilin 3A1 induce similar intracellular activation signaling in human TCRVγ9+ γδ T lymphocytes.

Human γδ cells expressing TCRVγ9 are T lymphocytes with great potential for cancer immunotherapy and unconventional pattern of antigen specificity. These HLA-unrestricted lymphocytes are specifically reactive to non-peptide metabolites (phosphoantigens) and to the butyrophilin 3A (BTN3A/CD277) protein. Whether recognition of such highly different structures trigger the same activation signaling pathway remains unclear, however. Here we combined fluorescent cell barcoding and phosphoflow analysis of TCRVγ9(+) T lymphocytes to compare simultaneously the level of several signaling phosphoproteins after activation by phosphoantigen (BrHPP) or by anti-BTN3A (monoclonal antibody 20.1). This approach shows that the same pathways involving ZAP70, PLCγ2, Akt, NFκB p65, MAPK p38 and Erk1, were induced by either of these stimuli. These data strongly suggest the TCRVγ9(+) T lymphocytes detect phosphoantigens and butyrophilin A3 by the same recognition process.