Suzanne van Dorp

Pitfalls of vaccinations with WT1-, Proteinase3- and MUC1-derived peptides in combination with MontanideISA51 and CpG7909

T cells with specificity for antigens derived from Wilms Tumor gene (WT1), Proteinase3 (Pr3), and mucin1 (MUC1) have been demonstrated to lyse acute myeloid leukemia (AML) blasts and multiple-myeloma (MM) cells, and strategies to enhance or induce such tumor-specific T cells by vaccination are currently being explored in multiple clinical trials. To test safety and immunogenicity of a vaccine composed of WT1-, Pr3-, and MUC1-derived Class I-restricted peptides and the pan HLA-DR T helper cell epitope (PADRE) or MUC1-helper epitopes in combination with CpG7909 and MontanideISA51, four patients with AML and five with MM were repetitively vaccinated. No clinical responses were observed. Neither pre-existing nor naive WT1-/Pr3-/MUC1-specific CD8+ T cells expanded in vivo by vaccination. In contrast, a significant decline in vaccine-specific CD8+ T cells was observed. An increase in PADRE-specific CD4+ T helper cells was observed after vaccination but these appeared unable to produce IL2, and CD4+ T cells with a regulatory phenotype increased. Taken into considerations that multiple clinical trials with identical antigens but different adjuvants induced vaccine-specific T cell responses, our data caution that a vaccination with leukemia-associated antigens can be detrimental when combined with MontanideISA51 and CpG7909. Reflecting the time-consuming efforts of clinical trials and the fact that 1/3 of ongoing peptide vaccination trails use CpG and/or Montanide, our data need to be taken into consideration.

Rituximab Treatment before Reduced-Intensity Conditioning Transplantation Associates with a Decreased Incidence of Extensive Chronic GVHD

Chronic graft-versus-host-disease (cGVHD) is the major cause of late morbidity and mortality after allogeneic stem cell transplantation. B cells have been reported to be involved in mediating cGVHD. To assess whether preemptive host B cell depletion prevents extensive cGVHD after allogeneic reduced-intensity conditioning transplantation (RICT), 173 patients treated with RICT for various hematologic diseases, who had or had not received Rituximab (Rtx) within 6 month prior to RICT, were analyzed retrospectively. Rtx treatment within 6 months prior to RICT reduced extensive cGVHD significantly from 45.8% to 20.1%. We hypothesize that most likely host B cells initiate cGVHD, and thus, host B cell depletion prior to RICT by Rtx might be a valuable strategy to reduce extensive cGVHD after RICT.

γ9 and δ2CDR3 domains regulate functional avidity of T cells harboring γ9δ2TCRs

Immunotherapy with innate immune cells has recently evoked broad interest as a novel treatment option for cancer patients. γ9δ2T cells in particular are emerging as an innate cell population with high frequency and strong antitumor reactivity, which makes them and their receptors promising candidates for immune interventions. However, clinical trials have so far reported only limited tumor control by adoptively transferred γ9δ2T cells. As a potential explanation for this lack of efficacy, we found unexpectedly high variability in tumor recognition within the physiologic human γ9δ2T-cell repertoire, which is substantially regulated by the CDR3 domains of individual γ9δ2TCRs. In the present study, we demonstrate that the reported molecular requirements of CDR3 domains to interact with target cells shape the physiologic γ9δ2T-cell repertoire and, most likely, limit the protective and therapeutic antitumor efficacy of γ9δ2T cells. Based on these findings, we propose combinatorial-γδTCR-chain exchange as an efficient method for designing high-affinity γ9δ2TCRs that mediate improved antitumor responses when expressed in αβT cells both in vitro and in vivo in a humanized mouse model.

Re-targeting T-cells against cancer by gene-transfer of tumor-reactive receptors

Background: Adoptive transfer of T-lymphocytes is a promising treatment for a variety of malignancies, but is often not feasible due to difficulties in generating T-cells reactive with the targeted antigen from patients. To facilitate rapid generation of cells for therapy, T-cells can be programmed with genes encoding for an antigen-specific T-cell receptor (TCR) or chimeric receptors. Objective: To discuss the molecular design and selected pitfalls of TCR gene modified T-cells and T-cells expressing chimeric receptors, so called T-bodies. Methods: A selected review of the recent literature. Conclusion: Clinical trials report so far only limited efficacy of adoptively transferred genetically modified T-cells. However, the recent progress in engineering tumor-reactive T cells is providing a promising basis to further explore this treatment modality.

Influence of Donor Cytomegalovirus (CMV) Status on Severity of Viral Reactivation after Allogeneic Stem Cell Transplantation in CMV-Seropositive Recipients

We investigated the role of donor cytomegalovirus (CMV) serostatus on reactivation of CMV infection in CMV-infected transplant recipients. Reactivation of CMV infection occurred more frequently in patients receiving a CMV-positive graft but was less severe than in patients receiving a CMV-negative graft. These data suggest roles for both virus as well as CMV-specific immunity present in the graft.

The immunological phenotype of rituximab-sensitive chronic graft-versus-host disease: a phase II study

Chronic graft-versus-host disease is the major long-term complication after allogeneic stem cell transplantation with a suboptimal response rate to current treatments. Therefore, clinical efficacy and changes in lymphocyte subsets before and after rituximab treatment were evaluated in a prospective phase II study in patients with steroid-refractory chronic graft-versus-host disease. Overall response rate was 61%. Only responding patients were found to have increased B-cell numbers prior to treatment. B cells had a naïve-antigen-presenting phenotype and were mainly CD5 negative or had a low CD5 expression. Normal B-cell homeostasis was reestablished in responding patients one year after ritxumab treatment and associated with a significant decline in skin-infiltrating CD8+ T cells, suggesting that host B cells play a role in maintaining pathological CD8+ T-cell responses. Imbalances in B-cell homeostasis could be used to identify patients a priori with a higher chance of response to rituximab treatment (Eudra-CT 2008-004125-42).

Secondary monoclonal gammopathy of undetermined significance after allogeneic stem cell transplantation in multiple myeloma

In the course of multiple myeloma, patients may develop a M-protein band different from the original: secondary monoclonal gammopathy of undetermined significance. In this retrospective single center analysis, we describe the occurrence and clinical relevance of secondary monoclonal gammopathy of undetermined significance after allogeneic stem cell transplantation (post-transplant monoclonal gammopathy of undetermined significance). A total of 138 patients who had undergone 139 allogeneic stem cell transplantations (39.6% in the upfront setting and 60.4% for relapsed multiple myeloma) were included in the study. Sixty-seven (48.2%) patients developed secondary monoclonal gammopathy of undetermined significance, after a median latency of 6.9 months. Secondary monoclonal gammopathy of undetermined significance occurred more often in patients who achieved at least very good partial response after allogeneic stem cell transplantation, compared to partial response or less (54.8% vs. 26.5%; P=0.005). The incidence was also higher in the upfront setting as compared to relapsed disease, or with a sibling donor compared to matched unrelated donor, but less often after T-cell depletion. Importantly, development of post-transplant monoclonal gammopathy of undetermined significance as a time-dependent variable independently predicted for superior progression-free and overall survival (median progression-free survival 37.5 vs. 6.3 months, P<0.001; median overall survival 115.3 vs. 31.0 months, P=0.004). Clinicians should be aware of the benign nature of this phenomenon, and secondary monoclonal gammopathy of undetermined significance should not be confused with relapse or progression of disease. (Trial registered with trialregister.nl; HOVON 108: NTR 2958.)

Histological Assessment of the Sclerotic Graft-versus-Host Response in the Humanized RAG2−/−γc−/− Mouse Model

Graft-versus-host disease (GVHD) remains a frequently occurring and difficult-to-treat complication in human allogeneic stem cell transplantation. Murine transplantation models are often used to study and understand the complex pathogenesis of GVHD and to explore new treatment strategies. Although GVHD kinetics may differ in murine and human models, adequate models are essential for identification of the crucial factors responsible for the major pathology in GVHD. We present a detailed description of the specific histological features of a graft-versus-host-induced fibrotic response in xenogeneic RAG2(-/-)γc(-/-) mice after total body irradiation and injection with human peripheral blood mononuclear cells. We describe the full morphological features of this reaction, including a detailed analysis of the specific tissue infiltration patterns of the human peripheral blood mononuclear cells. Our data show the development of fibrosis, predominantly near blood vessels, and reveal different cell populations and specific cell migration patterns in the affected organs. The combination of immunohistochemical cell characterization and mRNA expression analysis of both human (donor)- and murine (host)-derived cytokines reveals an interaction between host tissues and donor-derived cells in an entangled cytokine profile, in which both donor- and host-derived cytokines contribute to the formation of fibrosis.

Prospective evaluation of sequential treatment of sclerotic chronic graft versus host disease with rituximab and nilotinib

Sclerotic chronic graft vs. host disease (cGVHD) still has a large impact on morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). We performed the first prospective study to test whether sequential therapy of the anti-CD20 antibody rituximab followed by 6 months treatment with tyrosine kinase inhibitor nilotinib is a favorable treatment strategy for patients with sclerotic cGVHD. Twenty-nine patients were included, 24 were available for analysis. We observed objective responses in 71% of patients (two patients CR, 15 patients PR). Moreover, two out of five patients suffering from severe ulcerations showed complete resolution of ulcers. Observed responses lasted until the end of study follow-up. The majority of responding patients could reduce daily corticosteroid dose with more than 50%. Furthermore, CD5+ B-cells are significantly lower (p = 0.007) in responding patients at baseline, proposing a new biomarker predictive for response. In conclusion, sequential treatment of rituximab followed by nilotinib associates with a very high response rate in this difficult to treat patient population. CD5+ B-cells could assist in guiding treatment choices and might be a first step toward more personalized cGVHD treatment. This trial was registered at the Dutch clinical trial registry as NTR1222.