Mutations in the nucleophosmin gene (NPM1 mut ) are one of the most frequent molecular alterations in acute myeloid leukemia (AML), and immune responses may contribute to the favorable prognosis of AML patients with NPM1 mut . In the present study, we were able to demonstrate both CD4 ؉ and CD8 ؉ T-cell responses against NPM1 mut . Ten peptides derived from wild-type NPM1 and NPM1 mut were subjected to ELISPOT analysis in 33 healthy volunteers and 27 AML patients.Tetramer assays against the most interesting epitopes were performed and Cr 51 -release assays were used to show the cytotoxicity of peptide-specific T cells. Moreover, HLA-DR-binding epitopes were used to test the role of CD4 ؉ T cells in NPM1 immunogenicity. Two epitopes (epitopes #1 and #3) derived from NPM1 mut induced CD8 ؉ T-cell responses. A total of 33% of the NPM1 mut AML patients showed immune responses against epitope #1 and 44% against epitope #3. Specific lysis of leukemic blasts was detected. To obtain robust immune responses against tumor cells, the activation of CD4 ؉ T cells is crucial. Therefore, overlapping (OL) peptides were analyzed in ELISPOT assays and OL8 was able to activate both CD8 ؉ and CD4 ؉ T cells. The results of the present study show that NPM1 mut induces specific T-cell responses of CD4 ؉ and CD8 ؉ T cells and therefore is a promising target for specific immunotherapies in AML. (Blood. 2012;120(6):1282-1289) IntroductionMutations in the nucleophosmin 1 gene (NPM1 mut ) represent some of the most common gene mutations in acute myeloid leukemia (AML). 1,2 Falini et al first described the abnormal cytoplasmic localization of the NPM1 protein caused by mutations in exon 12 of the gene. 3 In AML patients with normal cytogenetics, the incidence of NPM1 mut was reported in up to 60% of the patients. 1-3 NPM1 constitutes an important prognostic marker, especially in the context of FMS-related tyrosine kinase internal tandem duplication (FLT3-ITD). In more than 90% of AML patients harboring NPM1 mut , the 3 different NPM1 mut types (A, B, and D) were found. 1,2,4-6 AML patients harboring an NPM1 mut without an FLT3-ITD mutation showed improved survival when treated with intensive chemotherapy. 2 Most AML patients with NPM1 mut seem not to benefit from an allogeneic stem cell transplantation as a first-line treatment. 2,7 However, this issue remains to be elucidated in the context of minimal residual disease detection 8 and the coexistence of other molecular markers. The functional role of NPM1 mut for the improved clinical outcome remains to be elucidated. Immune responses may contribute to clinical outcome by lysis of residual leukemic cells through specific T cells after chemotherapy. Leukemia-associated antigens (LAAs) can be targeted by the immune system in a specific manner, leading to the hypothesis that the expression of LAAs might also influence the clinical outcome of AML patients. mRNA expression of at least 1 of the 3 LAA, receptor for hyaluronic acid-mediated motility (RHAMM), preferentially expressed antigen in mela...

BackgroundRecently, we demonstrated immunological and clinical responses to a RHAMM-R3 peptide vaccine in patients with acute myeloid leukemia, myelodysplastic syndrome and multiple myeloma. To improve the outcome of the vaccine, a second cohort was vaccinated with a higher dose of 1,000 μg peptide. Design and MethodsNine patients received four vaccinations subcutaneously at a biweekly interval. Immunomonitoring of cytotoxic CD8+ as well as regulatory CD4 + T cells was performed by flow cytometry as well as by enzyme-linked immunospot (ELISpot) assays. Parameters of clinical response were assessed. ResultsIn 4 of 9 patients (44%) we detected positive immunological responses. These patients showed an increase of CD8-effector T cells and an increase of R3-specific CD8+ T cells. Two of these patients showed a significant decrease of regulatory T cells (Tregs). In one patient without response Tregs frequency increased from 5 to 16%. Three patients showed clinical effects: one patient with myelodysplastic syndrome RAEB-1 showed a reduction of leukemic blasts in the bone marrow, another myelodysplastic syndrome patient an improvement of peripheral blood counts and one patient with multiple myeloma a reduction of free light chains. Clinical and immunological reactions were lower in this cohort than in the 300 μg cohort. ConclusionsHigh-dose RHAMM-R3 peptide vaccination induced immunological responses and positive clinical effects. Therefore, RHAMM constitutes a promising structure for further targeted immunotherapies in patients with different hematologic malignancies. However, higher doses of peptide did not improve the frequency and intensity of immune responses in this trial. (This study is registered at http://ISRCTN.org as ISRCTN32763606)Key words: acute myeloid leukemia, leukemia-associated antigens, receptor for hyaluronic acid mediated motility, RHAMM/CD168, epitope peptides, cancer vaccines. Haematologica 2010;95:1191-1197. doi:10.3324/haematol.2009 This is an open-access paper.High-dose RHAMM-R3 peptide vaccination for patients with acute myeloid leukemia, myelodysplastic syndrome and multiple myeloma

IntroductionTherapy with chimeric antigen receptor T (CART) cells for hematological malignancies has shown promising results. Effectiveness of CART cells may depend on the ratio of naive (TN) vs. effector (TE) T cells, TN cells being responsible for an enduring antitumor activity through maturation. Therefore, we investigated factors influencing the TN/TE ratio of CART cells.Materials and methodsCART cells were generated upon transduction of peripheral blood mononuclear cells with a CD19.CAR-CD28-CD137zeta third generation retroviral vector under two different stimulating culture conditions: anti-CD3/anti-CD28 antibodies adding either interleukin (IL)-7/IL-15 or IL-2. CART cells were maintained in culture for 20 days. We evaluated 24 healthy donors (HDs) and 11 patients with chronic lymphocytic leukemia (CLL) for the composition of cell subsets and produced CART cells. Phenotype and functionality were tested using flow cytometry and chromium release assays.ResultsIL-7/IL-15 preferentially induced differentiation into TN, stem cell memory (TSCM: naive CD27+ CD95+), CD4+ and CXCR3+ CART cells, while IL-2 increased effector memory (TEM), CD56+ and CD4+ T regulatory (TReg) CART cells. The net amplification of different CART subpopulations derived from HDs and untreated CLL patients was compared. Particularly the expansion of CD4+ CARTN cells differed significantly between the two groups. For HDs, this subtype expanded >60-fold, whereas CD4+ CARTN cells of untreated CLL patients expanded less than 10-fold. Expression of exhaustion marker programmed cell death 1 on CARTN cells on day 10 of culture was significantly higher in patient samples compared to HD samples. As the percentage of malignant B cells was expectedly higher within patient samples, an excessive amount of B cells during culture could account for the reduced expansion potential of CARTN cells in untreated CLL patients. Final TN/TE ratio stayed <0.3 despite stimulation condition for patients, whereas this ratio was >2 in samples from HDs stimulated with IL-7/IL-15, thus demonstrating efficient CARTN expansion.ConclusionUntreated CLL patients might constitute a challenge for long-lasting CART effects in vivo since only a low number of TN among the CART product could be generated. Depletion of malignant B cells before starting CART production might be considered to increase the TN/TE ratio within the CART product.

Despite high response rates after initial chemotherapy in patients with acute myeloid leukemia (AML), relapses occur frequently, resulting in a five-year-survival by <30% of the patients. Hitherto, allogeneic hemotopoietic stem cell transplantation (allo-HSCT) is the best curative treatment option in intermediate and high risk AML. It is the proof-of-concept for T cell-based immunotherapies in AML based on the graft-versus-leukemia (GvL)-effect, but it also bears the risk of graft-versus-host disease. CD19-targeting therapies employing chimeric antigen receptor (CAR) T cells are a breakthrough in cancer therapy. A similar approach for myeloid malignancies is highly desirable. This article gives an overview on the state-of-the art of preclinical and clinical studies on suitable target antigens for CAR T cell therapy in AML patients.

Immune responses against the mutated region of cytoplasmatic NPM1 might contribute to the favorable clinical outcome of AML patients with NPM1 mutations (NPM1 mut )Immune responses directed against epitopes derived from the mutated region of nucleophosmin 1 (NPM1) by NPM1 mut -specific CD8(1) cytotoxic T cells (CTLs) might be involved in the rejection of NPM1 mut myeloid leukemic blasts. NPM1 mutations are one of the most frequent molecular alterations in acute myeloid leukemia (AML) and are an important prognostic marker.1 The mutations cause an abnormal shift of the NPM1 protein from the nucleus to the cytoplasm, described by Falini et al.2 AML patients with NPM1 mut , but without FLT3 internal tandem duplication (ITD) mutation, show improved overall survival.3 NPM1 mut /FLT3-ITD-negative patients do not seem to benefit from allogeneic stem cell transplantation in first-line treatment; however, this issue is still under evaluation, further clinical trials are ongoing, and also minimal residual disease (MRD) has to be considered in treatment decision. 3,4 The functional role of NPM1 mut for the improved clinical outcome is still under evaluation. Immune responses to NPM1 mut may contribute to favorable prognosis of this AML subtype. Recently, we described specific T-cell responses of CD4 1 and CD8 1 T cells against epitopes derived from mutated regions of NPM1. 5 Two NPM1 mut -derived peptides, called #1 and #3, induced specific T-cell responses in patients with NPM1 mut (33% and 44%, respectively). NPM1 mut AML patients showed a significantly higher frequency of CTL responses against peptide #3 compared with healthy volunteers (P 5 .046).5 Several leukemia-associated antigens (LAAs) have been defined, most importantly RHAMM, Proteinase 3, and Wilms' tumor antigen 1 (WT-1). These antigens were tested in clinical peptide vaccination trials. 6 Immunologic and clinical responses were detected in patients with different hematologic malignancies. 7,8 Berneman et al 9 discussed NPM1 mut as a further important LAA to attack AML and leukemic stem cells by autologous T cells.In this work, we performed survival analysis of 25 NPM1 mut patients ( Figure 1A), analyzed by enzyme-linked immunospot comparing cases with or without specific T-cell responses. Our data suggest a better overall survival of patients with specific CTL responses against peptide #1 or #3 (P 5 .004; Figure 1B).Immune responses seem to differ in dependence on the epitopes (P = .026; Figure 1C), although this finding has to be interpreted with caution due to the low number of patients. The survival rate of all NPM1 mut patients is lower due to other molecular alterations (like FLT3-ITD in 11 of 25 NPM1 mut patients) and the inclusion of elderly patients (7 of 25 were older than 60 years of age). Due to its exquisite specificity in leukemia, NPM1 mut might constitute an ideal target structure for individualized immunotherapeutic approaches. Analysis with material from larger controlled clinical trials has to be performed. Nevertheless, these data suggest...

[F]FDG-PET/CT before and shortly after allogeneic HCT is a powerful predictor for progression-free and overall survival in MM patients.

Chimeric antigen receptor (CAR) T cells are considered genetically modified organisms (GMOs) and constitute gene therapy medicinal products. Thus, CAR T cell manufacturing for clinical application is strictly regulated. Appropriate methods to assess vector copy numbers (VCNs) in CAR T cell products and monitoring of CAR T cell frequencies in patients are required. Quantitative polymerase chain reaction (qPCR) is the preferred method for VCN assessment. However, no standardized procedure with high reproducibility has been described yet. Here, we report on a single copy gene (SCG)based duplex (DP)-qPCR assay (SCG-DP-PCR) to determine VCN in CAR T cell products. SCG-DP-PCR was validated and compared to the absolute standard curve method (ACM) within the framework of a clinical trial treating patients with good manufacturing practice (GMP)-grade CAR T cells at the University Hospital Heidelberg. Methodologically, SCG-DP-PCR displayed technical advantages over ACM and minimized mathematical analysis. SCG-DP-PCR, as a highly reproducible approach, can be used for clinical follow-up of patients treated with CAR T cells or other GMOs and might replace established methods for VCN quantification. This work will enable clinicians to assess VCN, as well as CAR T cell frequencies, in patients as a basis for decisions on subsequent therapies, including repeated CAR T cell administration.

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