Anke Janssen’s research while affiliated with University Medical Center Utrecht and other places

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) aims to cure patients without inducing severe graft-versus-host disease (GVHD) or relapse. In prospective studies of mostly pediatric patients with haploidentical donors, ex vivo αβTCR/CD19 depletion has shown to have low incidences of GVHD, but data for adults with matched related (MRD) or unrelated donors (MUD) remain limited. We analyzed the outcomes of recipients who received a myeloablative regimen plus ATG, followed by an αβTCR/CD19-depleted allograft (cohort D+ATG (n = 122)), and compared outcomes to T cell-replete cohorts (cohort R (N = 60)); without ATG; R+ATG = with ATG (N = 129) in a single-center retrospective analysis. In D+ATG, the incidence of aGVHD grade III–IV was 7%, compared to 13% in R and 16% in R+ATG (p = 0.09). Extensive cGVHD was reduced from 23% in R and 10% in R+ATG to 2% in D+ATG (p < 0.001). The reduced incidence of cGVHD led to a superior GVHD-relapse-free survival (GRFS) of 56.7% in D+ATG versus 36.7% in R and 42.8% in R+ATG (p = 0.03) at 2 years. In conclusion, the combination of myeloablative conditioning, ATG, and ex vivo αβTCR/CD19 depletion appears to be a promising approach to enhance GRFS in adult patients up to 75 years of age undergoing allo-HSCT.

Introduction The aim of allogeneic stem cell transplantation (allo-SCT) is to reach graft-versus-host disease, relapse free survival (GRFS). To reduce the incidence of graft-versus-host disease (GVHD), we have developed an allo-SCT platform combining ex vivo αβTCR/CD19 depletion with in vivo T-cell depletion through administration of antithymoglobulin (ATG). Here we compare GRFS to historical cohorts of T-cell replete allo-SCT. Methods Adults with hematological malignancies and transplanted between 2011 and 2022 were included in this retrospective analysis. Written informed consent was obtained in accordance with the JACIE guidelines. Clinical data was extracted from the EBMT registry. 3 cohorts were identified. Cohort A: Allo-SCT of unmanipulated peripheral blood derived mononuclear cells (PBMCs) of matched related donors (MRD) after non-myeloablative (NMA) or myeloablative (MA) conditioning without ATG. Cohort B: Allo-SCT of unmanipulated PBMCs of 10/10 or 9/10 matched unrelated donors (MUD) after NMA or MA conditioning with ATG. Patients in cohorts A & B received dual immunosuppression with cyclosporin (CsA) and mycophenolic acid (MMF). Cohort C: Allo-SCT of αβTCR/CD19 depleted PBMCs of MRD and MUD (10/10 and 9/10) after ATG and a myeloablative conditioning as previously described[1]. Patients in cohort C received 28 days of MMF. Cumulative incidence (CI) of GVHD was defined as time to onset of GVHD, with relapse and death as competing events. Overall survival (OS) was defined as time to death from any cause. CI of relapse was defined as time to relapse, with death as a competing event. Non-relapse mortality (NRM) was defined as time to death, without relapse or progression. Event free survival (EFS) was defined as the time to relapse, graft failure or death. GRFS was defined as the time to relapse, aGVHD 3-4 or extensive cGVHD, graft failure or death. CI of CMV and EBV reactivations were calculated with relapse and death as competing events. Results 341 patients were included (cohort A: N=63; cohort B: N=150; cohort C: N=128) (table 1). In T cell replete allo-SCT (A&B) ATG was administered to recipients of MUD and MA conditioning was administered to patients < 40 years with acute leukemia. In cohort C, all patients received ATG and an MA conditioning, regardless of age or underlying malignancy. This explains differences donor types and intensity of conditioning between the cohorts (table 1). Other clinical characteristics were comparable. Two year OS (A=66.7%; B=58.7%; C=63.8%) and EFS (A=57.1%; B=52%; C=55.7%) was comparable between the cohorts. Two year CI of relapse was also comparable (A=30%; B=23%; C=28%). Two year NRM appeared higher in B, but this difference did not reach significance (A= 9.8%; B=24%; C=15%). The CI of aGVHD grade 2-4 and 3-4 at day 100 was significantly higher in T cell replete allo-SCT with MUD (2-4; A=23%; B=37%; C=20% (p=0.002); 3-4: A=5%; B=16%; C=4.7% (p=0.043)). The incidence of extensive cGVHD was significantly higher in T cell replete allo-SCT of MRD. (A= 25%; B=13%; C= 2.3% (p=< 0.001)). The low incidence of grade 3-4 aGVHD and extensive cGVHD without an increase in relapse or NRM, translated into a superior 2 year GRFS in patients receiving ATG combined with an αβTCR/CD19 allograft (C=55.6%) as compared to T cell replete allo-HSCT of MRD (A=38.1%) and MUD (B=40.8%) (Figure 1, p=0.04). This difference remained significant in a multivariate analysis. Conclusion We demonstrate that αβTCR/CD19 depletion combined with ATG, with a myeloablative conditioning and a very short course of immunosuppression results in very low incidences of life-threatening GVHD and an improved GRFS as compared to T cell replete allo-SCT for adult patients up to the age of 70. This is likely to positively impact the long term quality of life in survivors of allo-SCT[2]. In addition, this platform provides a window for additional early post allo-interventions to further improve the control of underlying hematological malignancies. 1. de Witte, M.A., et al., alphabeta T-cell graft depletion for allogeneic HSCT in adults with hematological malignancies. Blood Adv, 2021. 5(1): p. 240-249. 2. Oerlemans, S., et al. Relapse and severe Graft-versus-Host Disease have a negative impact on long-term symptoms and quality of life of patients three years after allogeneic haematopoietic stem cell transplantation. Annual meeting EBMT 2022.

γ9δ2T cells fill a distinct niche in human immunity due to the unique physiology of the phosphoantigen-reactive γ9δ2TCR. Here, we highlight reproducible TCRδ complementarity-determining region 3 (CDR3δ) repertoire patterns associated with γ9δ2T cell proliferation and phenotype, thus providing evidence for the role of the CDR3δ in modulating in vivo T-cell responses. Features that determine γ9δ2TCR binding affinity and reactivity to the phosphoantigen-induced ligand in vitro appear to similarly underpin in vivo clonotypic expansion and differentiation. Likewise, we identify a CDR3δ bias in the γ9δ2T cell natural killer receptor (NKR) landscape. While expression of the inhibitory receptor CD94/NKG2A is skewed toward cells bearing putative high-affinity TCRs, the activating receptor NKG2D is expressed independently of the phosphoantigen-sensing determinants, suggesting a higher net NKR activating signal in T cells with TCRs of low affinity. This study establishes consistent repertoire–phenotype associations and justifies stratification for the T-cell phenotype in future research on γ9δ2TCR repertoire dynamics.

In the complex interplay between inflammation and graft-versus-host disease (GVHD) after allogeneic stem cell transplantation (allo-HSCT), viral reactivations are often observed and cause substantial morbidity and mortality. As toxicity after allo-HSCT within the context of viral reactivations is mainly driven by αβ T cells, we describe that by delaying αβ T cell reconstitution through defined transplantation techniques, we can harvest the full potential of early reconstituting γδ T cells to control viral reactivations. We summarize evidence of how the γδ T cell repertoire is shaped by CMV and EBV reactivations after allo-HSCT, and their potential role in controlling the most important, but not all, viral reactivations. As most γδ T cells recognize their targets in an MHC-independent manner, γδ T cells not only have the potential to control viral reactivations but also to impact the underlying hematological malignancies. We also highlight the recently re-discovered ability to recognize classical HLA-molecules through a γδ T cell receptor, which also surprisingly do not associate with GVHD. Finally, we discuss the therapeutic potential of γδ T cells and their receptors within and outside the context of allo-HSCT, as well as the opportunities and challenges for developers and for payers.

abT cells engineered to express a defined gdTCR (TEG) to attack cancer cells have shown great promise when using a g9d2TCR to redirect abT cells. Reports by us and recent reports by others support the key role of the g9d2TCR in cancer recognition. We further emphasized the crucial role of the dTCR chain and that differences in CDR3 sequences of the dTCR chain modulates functional avidity of TEGs. We and others demonstrated that also d2 negative gdTCRs are able to redirect abT cells towards different tumor cell lines. However, some studies suggest that d2 negative gdTCRs play a minor role in the tumor recognition by d2 negative gdT cells. In addition for both modes of action for tumor-recognition, d2 negative gdTCR-dependent and -independent, it has been suggested that CMV infection is not only a major driver of d2 negative gdT cell expansion but also induces tumor-cross reactive d2 negative gdT cells. Therefore, we aimed to systematically explore frequencies of tumor reactive d2 negative gdT cells in naive repertoires (cord blood) and patients with or without CMV infection and examined the potential role the parental d2 negative gdTCR in anti-tumor reactivity of selected clones. We observed that approximately 30% of all tested clones were tumor-reactive, though no differences were observed between different sources. Surprisingly, none of the so far tested gdTCR did mediate strong anti-tumor reactivity of the parental clones. Though numbers of tested TCR sequences are still low, our data imply that tumor-reactivity of d2 negative gdT cells is frequently not mediated by the d2 negative gdTCR alone.

Lymphocyte numbers need to be quite tightly regulated. It is generally assumed that lymphocyte production and lifespan increase homeostatically when lymphocyte numbers are low, and vice versa return to normal once cell numbers have normalized. This widely-accepted concept is largely based on experiments in mice, but is hardly investigated in vivo in humans. Here we quantified lymphocyte production and loss rates in vivo in patients 0.5-1 year after their autologous hematopoietic stem cell transplantation (autoHSCT). We indeed found that the production rates of most T-cell and B-cell subsets in autoHSCT-patients were 2 to 8-times higher than in healthy controls, but went hand in hand with a 3 to 9-fold increase in cell loss rates. Both rates also did not normalize when cell numbers did. This shows that increased lymphocyte production and loss rates occur even long after autoHSCT and can persist in the face of apparently normal cell numbers.

We conducted a multicenter prospective single-arm phase 1/2 study that assesses the outcome of αβ T-cell depleted allogeneic hematopoietic stem cell transplantation (allo-HSCT) of peripheral blood derived stem cells from matched related, or unrelated donors (10/10 and 9/10) in adults, with the incidence of acute graft-versus-host disease (aGVHD) as the primary end point at day 100. Thirty-five adults (median age, 59; range, 19-69 years) were enrolled. Conditioning consisted of antithymocyte globulin, busulfan, and fludarabine, followed by 28 days of mycophenolic acid after allo-HSCT. The minimal follow-up time was 24 months. The median number of infused CD34+ cells and αβ T cells were 6.1 × 106 and 16.3 × 103 cells per kg, respectively. The cumulative incidence (CI) of aGVHD grades 2-4 and 3-4 at day 100 was 26% and 14%. One secondary graft failure was observed. A prophylactic donor lymphocyte infusion (DLI) (1 × 105 CD3+ T cells per kg) was administered to 54% of the subjects, resulting in a CI of aGVHD grades 2-4 and 3-4 to 37% and 17% at 2 years. Immune monitoring revealed an early reconstitution of natural killer (NK) and γδ T cells. Cytomegalovirus reactivation associated with expansion of memory-like NK cells. The CI of relapse was 29%, and the nonrelapse mortality 32% at 2 years. The 2-year CI of chronic GVHD (cGVHD) was 23%, of which 17% was moderate. We conclude that only 26% of patients developed aGVHD 2-4 after αβ T-cell–depleted allo-HSCT within 100 days and was associated with a low incidence of cGVHD after 2 years. This trial was registered at www.trialregister.nl as #NL4767.

γ9δ2T cells play a major role in cancer immune surveillance, yet the clinical translation of their in vitro promise remains challenging. To address limitations of previous clinical attempts utilizing expanded γ9δ2T cells, we explored the clonal diversity of γ9δ2T cell repertoires and characterized their target. We demonstrated that only a fraction of expanded γ9δ2T cells is active against cancer cells, and that activity of the parental clone, or functional avidity of selected γ9δ2TCRs does not associate with clonal frequency. We also analyzed the target-receptor-interface and provided a two-receptor, three-ligand model. Activation is initiated by binding of the γ9δ2TCR to BTN2A1 through the regions between CDR2 and CDR3 of the TCR γ chain, and modulated by the affinity of the CDR3 region of the TCR δ chain, which is phosphoantigen (pAg)-independent and does not depend on CD277. CD277 is secondary, serving as mandatory co-activating ligand. Binding of CD277 to its putative ligand does not depend on the presence of γ9δ2TCR, does depend on usage of the intracellular CD277, creates pAg-dependent proximity to BTN2A1, enhances cell-cell conjugate formation and stabilizes the immunological synapse. This process critically depends on the affinity of the γ9δ2TCR and requires membrane flexibility of the γ9δ2TCR and CD277, facilitating their polarization and high-density recruitment during immunological synapse formation.

Background & Aim Despite extensive usage of gene therapy medicinal products (GTMPs) in clinical studies and recent approval of CAR T cell therapy, little information has been made available on the precise molecular characterization and possible variations in terms of insert integrity and vector copy numbers of different GTMPs during the complete production chain. Within this context we characterize αβT cells Engineered to express a defined γδT cell receptor (TEGs) currently used in a first-in-human clinical study (NTR6541). Methods, Results & Conclusion Utilizing Targeted Locus Amplification in combination with Next Generation Sequencing for the vector producer clone and TEG001 products we report on 5 single nucleotide variants and 9 intact vector copies integrated in the producer clone. The vector copy number in TEG001 cells was on average a factor 0.72 (SD 0.11) below that of the producer cell clone. All nucleotide variants were transferred to TEG001, without having an effect on cellular proliferation during extensive in vitro culture. Based on an environmental risk assessment of the 5 nucleotide variants present in the non-coding viral region of the TEG001 insert, there was no altered environmental impact of TEG001 cells. We conclude that TEG001 cells do not have an increased risk for malignant transformation in vivo. In conclusion, we have reported an extensive molecular characterization of TEG001 transgene integrity that resulted in the approval a phase I clinical study which did not only allow to investigate the safety and tolerability of TEG001 in patients with relapsed/refractory acute myeloid leukemia, high-risk myelodysplastic syndrome, and relapsed/refractory multiple myeloma but also will provide a valuable framework for the molecular characterisation of future GTMPs.