Anniek B. van der Waart

Inhibition of Akt signaling promotes the generation of superior tumor-reactive T cells for adoptive immunotherapy

Effective T-cell therapy against cancer is dependent on the formation of long-lived, stem cell-like T cells with the ability to self-renew and differentiate into potent effector cells. Here, we investigated the in vivo existence of stem cell-like antigen-specific T cells in allogeneic stem cell transplantation (allo-SCT) patients and their ex vivo generation for additive treatment posttransplant. Early after allo-SCT, CD8+ stem cell memory T cells targeting minor histocompatibility antigens (MiHAs) expressed by recipient tumor cells were not detectable, emphasizing the need for improved additive MiHA-specific T-cell therapy. Importantly, MiHA-specific CD8+ T cells with an early CCR7+CD62L+CD45RO+CD27+CD28+CD95+ memory-like phenotype and gene signature could be expanded from naive precursors by inhibiting Akt signaling during ex vivo priming and expansion. This resulted in a MiHA-specific CD8+ T-cell population containing a high proportion of stem cell-like T cells compared with terminal differentiated effector T cells in control cultures. Importantly, these Akt-inhibited MiHA-specific CD8+ T cells showed a superior expansion capacity in vitro and in immunodeficient mice and induced a superior antitumor effect in intrafemural multiple myeloma-bearing mice. These findings provide a rationale for clinical exploitation of ex vivo-generated Akt-inhibited MiHA-specific CD8+ T cells in additive immunotherapy to prevent or treat relapse in allo-SCT patients.

Natural Killer Cells Generated from Cord Blood Hematopoietic Progenitor Cells Efficiently Target Bone Marrow-Residing Human Leukemia Cells in NOD/SCID/IL2Rgnull Mice

Natural killer (NK) cell-based adoptive immunotherapy is an attractive adjuvant treatment option for patients with acute myeloid leukemia. Recently, we reported a clinical-grade, cytokine-based culture method for the generation of NK cells from umbilical cord blood (UCB) CD34+ hematopoietic progenitor cells with high yield, purity and in vitro functionality. The present study was designed to evaluate the in vivo anti-leukemic potential of UCB-NK cells generated with our GMP-compliant culture system in terms of biodistribution, survival and cytolytic activity following adoptive transfer in immunodeficient NOD/SCID/IL2Rgnull mice. Using single photon emission computed tomography, we first demonstrated active migration of UCB-NK cells to bone marrow, spleen and liver within 24 h after infusion. Analysis of the chemokine receptor expression profile of UCB-NK cells matched in vivo findings. Particularly, a firm proportion of UCB-NK cells functionally expressed CXCR4, what could trigger BM homing in response to its ligand CXCL12. In addition, high expression of CXCR3 and CCR6 supported the capacity of UCB-NK cells to migrate to inflamed tissues via the CXCR3/CXCL10-11 and CCR6/CCL20 axis. Thereafter, we showed that low dose IL-15 mediates efficient survival, expansion and maturation of UCB-NK cells in vivo. Most importantly, we demonstrate that a single UCB-NK cell infusion combined with supportive IL-15 administration efficiently inhibited growth of human leukemia cells implanted in the femur of mice, resulting in significant prolongation of mice survival. These preclinical studies strongly support the therapeutic potential of ex vivo-generated UCB-NK cells in the treatment of myeloid leukemia after immunosuppressive chemotherapy.

Decreased Levels of Circulating IL17-Producing CD161+CCR6+ T Cells Are Associated with Graft-versus-Host Disease after Allogeneic Stem Cell Transplantation

The C-type lectin-like receptor CD161 is a well-established marker for human IL17-producing T cells, which have been implicated to contribute to the development of graft-versus-host disease (GVHD) after allogeneic stem cell transplantation (allo-SCT). In this study, we analyzed CD161+ T cell recovery, their functional properties and association with GVHD occurrence in allo-SCT recipients. While CD161+CD4+ T cells steadily recovered, CD161hiCD8+ T cell numbers declined during tapering of Cyclosporine A (CsA), which can be explained by their initial growth advantage over CD161neg/lowCD8+ T cells due to ABCB1-mediated CsA efflux. Interestingly, occurrence of acute and chronic GVHD was significantly correlated with decreased levels of circulating CD161+CD4+ as well as CD161hiCD8+ T cells. In addition, these subsets from transplanted patients secreted high levels of IFNγ and IL17. Moreover, we found that CCR6 co-expression by CD161+ T cells mediated specific migration towards CCL20, which was expressed in GVHD biopsies. Finally, we demonstrated that CCR6+ T cells indeed were present in these CCL20+ GVHD-affected tissues. In conclusion, we showed that functional CD161+CCR6+ co-expressing T cells disappear from the circulation and home to GVHD-affected tissue sites. These findings support the hypothesis that CCR6+CD161-expressing T cells may be involved in the immune pathology of GVHD following their CCL20-dependent recruitment into affected tissues.

Targeting the IL17 Pathway for the Prevention of Graft-Versus-Host Disease

Graft-versus-host disease (GVHD) is still a major complication of allogeneic stem cell transplantation (allo-SCT). The pathophysiology of GVHD is a multistep process initiated by tissue damage and proinflammatory cytokine cascades induced by the pretransplantation conditioning therapy. This eventually results in Th1-driven tissue damage. However, increasing evidence indicates the involvement of IL17-producing T cells in GVHD pathogenesis. Both CD4(+) and CD8(+) IL17-producing T cells are suspected of initiating the Th1 response and aggravating tissue inflammation, resulting in full-blown GVHD. In this review, we discuss the involvement of IL17-producing T cells in GVHD and the factors involved in their expansion, differentiation, and activation. Different dendritic cell (DC) subsets, such as plasmacytoid DCs and DC NK lectin group receptor 1(+) myeloid DCs have the capability to stimulate Th/Tc17 responses through the release of cytokines. Pivotal cytokines include IL1β, IL6, IL23, and TGFβ, which are known to drive differentiation and expansion of IL17-producing T cells, and these cytokines are highly elevated in patients after allo-SCT. Potent activators of these DC subsets are motifs that are released upon tissue damage and microbial exposure during allo-SCT. These motifs aggravate the Th/Tc17 response via the activation of various pathogen recognition receptors, thereby initiating and perpetuating GVHD. A more comprehensive understanding of the factors and DC subsets driving the IL17 pathway will result in developing and testing novel therapeutic approaches for the prevention of GVHD.

siRNA silencing of PD-1 ligands on dendritic cell vaccines boosts the expansion of minor histocompatibility antigen-specific CD8(+) T cells in NOD/SCID/IL2Rg(null) mice

Abstract Allogeneic stem cell transplantation (allo-SCT) can be a curative therapy for patients suffering from hematological malignancies. The therapeutic efficacy is based on donor-derived CD8+ T cells that recognize minor histocompatibility antigens (MiHAs) expressed by patient’s tumor cells. However, these responses are not always sufficient, and persistence and recurrence of the malignant disease are often observed. Therefore, application of additive therapy targeting hematopoietic-restricted MiHAs is essential. Adoptive transfer of MiHA-specific CD8+ T cells in combination with dendritic cell (DC) vaccination could be a promising strategy. Though effects of DC vaccination in anti-cancer therapy have been demonstrated, improvement in DC vaccination therapy is needed, as clinical responses are limited. In this study, we investigated the potency of program death ligand (PD-L) 1 and 2 silenced DC vaccines for ex vivo priming and in vivo boosting of MiHA-specific CD8+ T cell responses. Co-culturing CD8+ T cells with MiHA-loaded DCs resulted in priming and expansion of functional MiHA-specific CD8+ T cells from the naive repertoire, which was augmented upon silencing of PD-L1 and PD-L2. Furthermore, DC vaccination supported and expanded adoptively transferred antigen-specific CD8+ T cells in vivo. Importantly, the use of PD-L silenced DCs improved boosting and further expansion of ex vivo primed MiHA-specific CD8+ T cells in immunodeficient mice. In conclusion, adoptive transfer of ex vivo primed MiHA-specific CD8+ T cells in combination with PD-L silenced DC vaccination, targeting MiHAs restricted to the hematopoietic system, is an interesting approach to boost GVT immunity in allo-SCT patients and thereby prevent relapse.

Successful Transfer of Umbilical Cord Blood CD34+ Hematopoietic Stem and Progenitor-derived NK Cells in Older Acute Myeloid Leukemia Patients

Purpose: Older acute myeloid leukemia (AML) patients have a poor prognosis; therefore, novel therapies are needed. Allogeneic natural killer (NK) cells have been adoptively transferred with promising clinical results. Here, we report the first-in-human study exploiting a unique scalable NK-cell product generated ex vivo from CD34+ hematopoietic stem and progenitor cells (HSPC) from partially HLA-matched umbilical cord blood units. Experimental Design: Ten older AML patients in morphologic complete remission received an escalating HSPC-NK cell dose (between 3 and 30 × 106/kg body weight) after lymphodepleting chemotherapy without cytokine boosting. Results: HSPC-NK cell products contained a median of 75% highly activated NK cells, with <1 × 104 T cells/kg and <3 × 105 B cells/kg body weight. HSPC-NK cells were well tolerated, and neither graft-versus-host disease nor toxicity was observed. Despite no cytokine boosting being given, transient HSPC-NK cell persistence was clearly found in peripheral blood up to 21% until day 8, which was accompanied by augmented IL15 plasma levels. Moreover, donor chimerism up to 3.5% was found in bone marrow. Interestingly, in vivo HSPC-NK cell maturation was observed, indicated by the rapid acquisition of CD16 and KIR expression, while expression of most activating receptors was sustained. Notably, 2 of 4 patients with minimal residual disease (MRD) in bone marrow before infusion became MRD negative (<0.1%), which lasted for 6 months. Conclusions: These findings indicate that HSPC-NK cell adoptive transfer is a promising, potential “off-the-shelf” translational immunotherapy approach in AML. Clin Cancer Res; 23(15); 4107–18. ©2017 AACR.

Combined IL-15 and IL-12 drives the generation of CD34+-derived natural killer cells with superior maturation and alloreactivity potential following adoptive transfer

Adoptive transfer of allogeneic natural killer (NK) cells represents a promising treatment approach against cancer, including acute myeloid leukemia (AML). Previously, we reported a cytokine-based culture method for the generation of NK cell products with high cell number and purity. In this system, CD34+ hematopoietic progenitor cells (HPC) were expanded and differentiated into NK cells under stroma-free conditions in the presence of IL-15 and IL-2. We show that combining IL-15 with IL-12 drives the generation of more mature and highly functional NK cells. In particular, replacement of IL-2 by IL-12 enhanced the cytolytic activity and IFNγ production of HPC-NK cells toward cultured and primary AML cells in vitro, and improved antileukemic responses in NOD/SCID-IL2Rγnull (NSG) mice bearing human AML cells. Phenotypically, IL-12 increased the frequency of HPC-NK cells expressing NKG2A and killer immunoglobulin-like receptor (KIR), which were more responsive to target cell stimulation. In addition, NK15/12 cell products demonstrated superior maturation potential, resulting in >70% positivity for CD16 and/or KIR within 2 weeks after infusion into NSG mice. We predict that higher functionality and faster in vivo maturation will favor HPC-NK cell alloreactivity toward malignant cells in patients, making this cytokine combination an attractive strategy to generate clinical HPC-NK cell products for cancer adoptive immunotherapy.

Polymorphisms in CCR6 Are Associated with Chronic Graft-versus-Host Disease and Invasive Fungal Disease in Matched-Related Hematopoietic Stem Cell Transplantation

Graft-versus-host disease (GVHD) and fungal infections are frequent complications after allogeneic hematopoietic stem cell transplantation (HSCT). Single nucleotide polymorphisms (SNPs) in genes of the immune system can influence the inflammatory cascade and T cell-driven alloimmune reactions after HSCT, and thus increasing the incidence of GVHD and infectious complications. Here, we investigated the effect of SNPs in IL-23R and CCR6 on posttransplantation outcome in 161 recipients of partially T cell-depleted HSCT. Remarkably, IL-23R SNPs were not associated with clinical outcome, but we found that disparities in the CCR6 tagSNP rs2301436 and SNP rs3093023 are independently associated with the occurrence of chronic GVHD (cGVHD) and invasive fungal disease. In multivariate analysis, patients receiving a transplant from a homozygous rs2301436 G allele donor showed less cGVHD (odds ratio [OR]: 0.16; P = .002), as was the case for a homozygous donor rs3093023 G allele (OR: 0.24; P = .005). In parallel, the GG genotype at rs2301436 in donors was associated with a higher incidence of invasive fungal disease at day 100 after HSCT (OR: 3.59; P = .008). This study shows that CCR6 SNPs can be used to predict clinical outcome, and that polymorphisms in the CCR6 gene may influence T cell-mediated immune reactions after HSCT.

Time to Akt: Superior tumor-reactive T cells for adoptive immunotherapy.

T cells are crucial players in the protection against cancer, and can be used in adoptive cell therapy to prevent or treat relapse. However, their state of differentiation determines their effectiveness, with early memory cells being the most favorable. Here, we discuss restraining of differentiation to engineer the ultimate tumor-reactive T cell.

Ex vivo AKT-inhibition facilitates generation of polyfunctional stem cell memory-like CD8+ T cells for adoptive immunotherapy

ABSTRACT Adoptive T cell therapy has shown clinical potential for patients with cancer, though effective treatment is dependent on longevity and potency of the exploited tumor-reactive T cells. Previously, we showed that ex vivo inhibition of AKT using the research compound Akt-inhibitor VIII retained differentiation and improved functionality of minor histocompatibility antigen (MiHA)-specific CD8+ T cells. Here, we compared a panel of clinically applicable AKT-inhibitors with an allosteric or adenosine triphosphate-competitive mode of action. We analyzed phenotype, functionality, metabolism and transcriptome of AKT-inhibited CD8+ T cells using different T cell activation models. Most inhibitors facilitated T cell expansion while preserving an early memory phenotype, reflected by maintenance of CD62L, CCR7 and CXCR4 expression. Moreover, transcriptome profiling revealed that AKT-inhibited CD8+ T cells clustered closely to naturally occurring stem cell-memory CD8+ T cells, while control T cells resembled effector-memory T cells. Interestingly, AKT-inhibited CD8+ T cells showed enrichment of hypoxia-associated genes, which was consistent with enhanced glycolytic function. Notably, AKT-inhibition during MiHA-specific CD8+ T cell priming uncoupled preservation of early memory differentiation from ex vivo expansion. Furthermore, AKT-inhibited MiHA-specific CD8+ T cells showed increased polyfunctionality with co-secretion of IFN-γ and IL-2 upon antigen recall. Together, these data demonstrate that AKT-inhibitors with different modality of action promote the ex vivo generation of stem cell memory-like CD8+ T cells with a unique metabolic profile and retained polyfunctionality. Akt-inhibitor VIII and GDC-0068 outperformed other inhibitors, and are therefore promising candidates for ex vivo generation of superior tumor-reactive T cells for adoptive immunotherapy in cancer patients.