Q-HAM: a multicenter upfront randomized phase II trial of quizartinib and high-dose Ara-C plus mitoxantrone in relapsed/refractory AML with FLT3-ITD

BACKGROUND

About 50% of older patients with acute myeloid leukemia (AML) fail to attain complete remission (CR) following cytarabine plus anthracycline-based induction therapy. Salvage chemotherapy regimens are based on high-dose cytarabine (HiDAC), which is frequently combined with mitoxantrone (HAM regimen). However, CR rates remain low, with less than one-third of the patients achieving a CR. FLT3-ITD has consistently been identified as an unfavorable molecular marker in both relapsed and refractory (r/r)-AML. One-quarter of patients who received midostaurin are refractory to induction therapy and relapse rate at 2 years exceeds 40%. The oral second-generation bis-aryl urea tyrosine kinase inhibitor quizartinib is a very selective FLT3 inhibitor, has a high capacity for sustained FLT3 inhibition, and has an acceptable toxicity profile.

METHODS

In this multicenter, upfront randomized phase II trial, all patients receive quizartinib combined with HAM (cytarabine 3g/m2 bidaily day one to day three, mitoxantrone 10mg/m2 days two and three) during salvage therapy. Efficacy is assessed by comparison to historical controls based on the matched threshold crossing approach with achievement of CR, complete remission with incomplete hematologic recovery (CRi), or complete remission with partial recovery of peripheral blood counts (CRh) as primary endpoint. During consolidation therapy (chemotherapy and allogeneic hematopoietic cell transplantation), patients receive either prophylactic quizartinib therapy or measurable residual disease (MRD)-triggered preemptive continuation therapy with quizartinib according to up-front randomization. The matched threshold crossing approach is a novel study-design to enhance the classic single-arm trial design by including matched historical controls from previous clinical studies. It overcomes common disadvantages of single-armed and small randomized studies, since the expected outcome of the observed study population can be adjusted based on the matched controls with a comparable distribution of known prognostic and predictive factors. Furthermore, balanced treatment groups lead to stable statistical models. However, one of the limitations of our study is the inability to adjust for unobserved or unknown confounders. Addressing the primary endpoint, CR/CRi/CRh after salvage therapy, the maximal sample size of 80 patients is assessed generating a desirable power of the used adaptive design, assuming a logistic regression is performed at a one-sided significance level α=0.05, the aspired power is 0.8, and the number of matching partners per intervention patient is at least 1. After enrolling 20 patients, the trial sample size will be recalculated in an interim analysis based on a conditional power argument.

CONCLUSION

Currently, there is no commonly accepted standard for salvage chemotherapy treatment. The objective of the salvage therapy is to reduce leukemic burden, achieve the best possible remission, and perform a hemopoietic stem-cell transplantation. Thus, in patients with FLT3-ITD mutation, the comparison of quizartinib with intensive salvage therapy versus chemotherapy alone appears as a logical consequence in terms of efficacy and safety.

ETHICS AND DISSEMINATION

Ethical approval and approvals from the local and federal competent authorities were granted. Trial results will be reported via peer-reviewed journals and presented at conferences and scientific meetings.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03989713; EudraCT Number: 2018-002675-17.

Treatment of adult ALL patients with third-generation CD19-directed CAR T cells: results of a pivotal trial

BACKGROUND

Third-generation chimeric antigen receptor (CAR)-engineered T cells (CARTs) might improve clinical outcome of patients with B cell malignancies. This is the first report on a third-generation CART dose-escalating, phase-1/2 investigator-initiated trial treating adult patients with refractory and/or relapsed (r/r) acute lymphoblastic leukemia (ALL).

METHODS

Thirteen patients were treated with escalating doses of CD19-directed CARTs between 1 × 10⁶ and 50 × 10⁶ CARTs/m². Leukapheresis, manufacturing and administration of CARTs were performed in-house.

RESULTS

For all patients, CART manufacturing was feasible. None of the patients developed any grade of Immune effector cell-associated neurotoxicity syndrome (ICANS) or a higher-grade (≥ grade III) catokine release syndrome (CRS). CART expansion and long-term CART persistence were evident in the peripheral blood (PB) of evaluable patients. At end of study on day 90 after CARTs, ten patients were evaluable for response: Eight patients (80%) achieved a complete remission (CR), including five patients (50%) with minimal residual disease (MRD)-negative CR. Response and outcome were associated with the administered CART dose. At 1-year follow-up, median overall survival was not reached and progression-free survival (PFS) was 38%. Median PFS was reached on day 120. Lack of CD39-expression on memory-like T cells was more frequent in CART products of responders when compared to CART products of non-responders. After CART administration, higher CD8 + and γδ-T cell frequencies, a physiological pattern of immune cells and lower monocyte counts in the PB were associated with response.

CONCLUSION

In conclusion, third-generation CARTs were associated with promising clinical efficacy and remarkably low procedure-specific toxicity, thereby opening new therapeutic perspectives for patients with r/r ALL. Trial registration This trial was registered at www.

CLINICALTRIALS

gov as NCT03676504.

Intensive chemotherapy with or without gemtuzumab ozogamicin in patients with NPM1-mutated acute myeloid leukaemia (AMLSG 09-09): a randomised, open-label, multicentre, phase 3 trial

BACKGROUND

Acute myeloid leukaemia with mutated NPM1 is associated with high CD33 expression and intermediate-risk cytogenetics. The aim of this study was to evaluate intensive chemotherapy with or without the anti-CD33 antibody-drug conjugate gemtuzumab ozogamicin in participants with newly diagnosed, NPM1-mutated acute myeloid leukaemia.

METHODS

This open-label, phase 3 trial was conducted at 56 hospitals in Germany and Austria. Eligible participants were 18 years or older and had newly diagnosed NPM1-mutated acute myeloid leukaemia and an Eastern Cooperative Oncology Group performance status of 0-2. Participants were randomly assigned, using age as a stratification factor (18-60 years vs >60 years), 1:1 to the two treatment groups using allocation concealment; there was no masking of participants and investigators to treatment groups. Participants received two cycles of induction therapy (idarubicin, cytarabine, and etoposide) plus all-trans retinoic acid (ATRA) followed by three consolidation cycles of high-dose cytarabine (or an intermediate dose for those older than 60 years) and ATRA, without or with gemtuzumab ozogamicin (3 mg/m2 administered intravenously on day 1 of induction cycles 1 and 2, and consolidation cycle 1). The primary endpoints were short-term event-free survival and overall survival in the intention-to-treat population (overall survival was added as a co-primary endpoint after amendment four of the protocol on Oct 13, 2013). The secondary endpoints were event-free survival with long-term follow-up, rates of complete remission, complete remission with partial haematological recovery (CRh), and complete remission with incomplete haematological recovery (CRi), cumulative incidences of relapse and death, and number of days in hospital. This trial is registered with ClinicalTrials.gov (NCT00893399) and has been completed.

FINDINGS

Between May 12, 2010, and Sept 1, 2017, 600 participants were enrolled, of which 588 (315 women and 273 men) were randomly assigned (296 to the standard group and 292 to the gemtuzumab ozogamicin group). No difference was found in short-term event-free survival (short-term event-free survival at 6-month follow-up, 53% [95% CI 47-59] in the standard group and 58% [53-64] in the gemtuzumab ozogamicin group; hazard ratio [HR] 0·83; 95% CI 0·65-1·04; p=0·10) and overall survival between treatment groups (2-year overall survival, 69% [63-74] in the standard group and 73% [68-78] in the gemtuzumab ozogamicin group; 0·90; 0·70-1·16; p=0·43). There was no difference in complete remission or CRi rates (n=267 [90%] in the standard group vs n=251 [86%] in the gemtuzumab ozogamicin group; odds ratio [OR] 0·67; 95% CI 0·40-1·11; p=0·15) and complete remission or CRh rates (n=214 [72%] vs n=195 [67%]; OR 0·77; 0·54-1·10; p=0·18), whereas the complete remission rate was lower with gemtuzumab ozogamicin (n=172 [58%] vs n=136 [47%]; OR 0·63; 0·45-0·80; p=0·0068). Cumulative incidence of relapse was significantly reduced by gemtuzumab ozogamicin (2-year cumulative incidence of relapse, 37% [95% CI 31-43] in the standard group and 25% [20-30] in the gemtuzumab ozogamicin group; cause-specific HR 0·65; 0·49-0·86; p=0·0028), and there was no difference in the cumulative incidence of death (2-year cumulative incidence of death 6% [4-10] in the standard group and 7% [5-11] in the gemtuzumab ozogamicin group; HR 1·03; 0·59-1·81; p=0·91). There were no differences in the number of days in hospital across all cycles between treatment groups. The most common treatment-related grade 3-4 adverse events were febrile neutropenia (n=135 [47%] in the gemtuzumab ozogamicin group vs n=122 [41%] in the standard group), thrombocytopenia (n=261 [90%] vs n=265 [90%]), pneumonia (n=71 [25%] vs n=64 [22%]), sepsis (n=85 [29%] vs n=73 [25%]). Treatment-related deaths were documented in 25 participants (4%; n=8 [3%] in the standard group and n=17 [6%] in the gemtuzumab ozogamicin group), mostly due to sepsis and infections.

INTERPRETATION

The primary endpoints of the trial of event-free survival and overall survival were not met. However, an anti-leukaemic efficacy of gemtuzumab ozogamicin in participants with NPM1-mutated acute myeloid leukaemia is shown by a significantly lower cumulative incidence of relapse rate, suggesting that the addition of gemtuzumab ozogamicin might reduce the need for salvage therapy in these participants. The results from this study provide further evidence that gemtuzumab ozogamicin should be added in the standard of care treatment in adults with NPM1-mutated acute myeloid leukaemia.

FUNDING

Pfizer and Amgen.

KIR2DS4 and its variant KIR1D in KIR-AA genotype donors showed differential survival impact in patients with lymphoid disease after HLA-matched unrelated hematopoietic stem cell transplantation

Previous studies illustrated associations between presence of activating killer cell immunoglobulin-like receptor (KIR) genes and lower susceptibility to hematologic malignancies in humans. In addition, favorable hematopoietic stem cell transplantation (HSCT) outcomes were reported in patients, who received transplants from donors with KIR genotypes dominant for activating KIR receptors. However, the association of activating KIR genes on an allelic level with disease and their impact on HSCT outcome has been only scarcely investigated. To this end, we genotyped a large transplantation cohort for KIR two Ig domains and short cytoplasmic tail 4 (KIR2DS4) polymorphisms and investigated their association with disease. We next investigated the impact of KIR-AA genotype donor KIR2DS4 polymorphisms (AA/KIR2DS4 versus (vs.) AA/KIR1D), on clinical outcome of HSCT in patient subgroups (myeloid vs. lymphoid). Among 2810 transplant pairs, 68.8% (n=1934) were 10/10 human leukocyte antigen (HLA) matched and 31.2% (n=876) were 9/10 HLA-matched. The distribution of KIR one Ig domain (KIR1D) in patients vs. donors was equal (P value = 0.205). Multivariate analysis in 10/10 HLA-matched patients with lymphoid disease showed improved HSCT outcome (overall survival (OS): hazard ratio (HR) 0.62, P=0.002; disease free survival (DFS): HR 0.70, P=0.011; graft-versus-host disease free and relapse-free survival (GRFS): HR 0.67, P=0.002; non-relapse mortality (NRM): HR 0.55, P<0.001) when they received grafts from AA/KIR1D donors. This effect was not seen in either 9/10 HLA-matched patients with lymphoid disease or patients with myeloid disease. Our study indicates that the presence of KIR1D alleles is not associated with disease in patients and interestingly, using grafts from AA/KIR1D donors translated into a beneficial survival outcome in 10/10 HLA-matched patients with lymphoid disease.

HLA-DRB3/4/5 Matching Improves Outcome of Unrelated Hematopoietic Stem Cell Transplantation

The HLA-DRB3/4/5 loci are closely linked to the HLA-DRB1 gene. Mismatches in these loci occur with a frequency of about 8%–12% in otherwise 10/10 HLA-matched transplant pairs. There is preliminary evidence that these disparities may associate with increased acute graft-versus-host disease (GvHD) rates. The aim of this study was to analyze a large cohort of German patients and their donors for HLA-DRB3/4/5 compatibility and to correlate the HLA-DRB3/4/5 matching status with the outcome of unrelated hematopoietic stem cell transplantation (uHSCT). To this end, 3,410 patients and their respective donors were HLA-DRB3/4/5 and HLA-DPB1 typed by amplicon-based next-generation sequencing (NGS). All patients included received their first allogeneic transplant for malignant hematologic diseases between 2000 and 2014. Mismatches in the antigen recognition domain (ARD) of HLA-DRB3/4/5 genes were correlated with clinical outcome. HLA-DRB3/4/5 incompatibility was seen in 12.5% (n = 296) and 17.8% (n = 185) of the 10/10 and 9/10 HLA-matched cases, respectively. HLA-DRB3/4/5 mismatches in the ARD associated with a worse overall survival (OS), as shown in univariate (5-year OS: 46.1% vs. 39.8%, log-rank p = 0.038) and multivariate analyses [hazard ratio (HR) 1.25, 95% CI 1.02–1.54, p = 0.034] in the otherwise 10/10 HLA-matched subgroup. The worse outcome was mainly driven by a significantly higher non-relapse mortality (HR 1.35, 95% CI 1.05–1.73, p = 0.017). In the 9/10 HLA-matched cases, the effect was not statistically significant. Our study results suggest that mismatches within the ARD of HLA-DRB3/4/5 genes significantly impact the outcome of otherwise fully matched uHSCT and support their consideration upon donor selection in the future.

The Human Leukocyte Antigen-DPB1 Degree of Compatibility Is Determined by Its Expression Level and Mismatch Permissiveness: A German Multicenter Analysis

T-cell epitope matching according to the TCE3 algorithm classifies HLA-DPB1 mismatches in permissive and non-permissive. This classification has been shown to be predictive for mortality and acute GvHD (aGvHD) events in large international cohorts. We retrospectively genotyped HLA-DPB1 in 3523 patients transplanted in Germany between 2000 and 2014 and in their unrelated donors using an Illumina amplicon-NGS based assay. Aim of the study was to evaluate DP-compatibility beyond the established TCE3 algorithm by assessing the combined effect of several DP-mismatch parameters on post-transplant outcome. We implemented an extended DP-mismatch assessment model where TCE3, DP allotype expression with respect to rs9277534, mismatch vector and number of mismatches were conjointly taken into consideration. In this model, non-permissive HLA-DPB1 mismatches showed significantly increased aGvHD risk if they were accompanied by two HLA-DPB1 mismatches in GvH direction (HR: 1.46) or one mismatched highly expressed patient allotype (HR: 1.53). As previously reported, non-permissive HLA-DPB1 mismatches associated with a significantly higher risk of aGvHD and non-relapse mortality (HR 1.36 and 1.21, respectively), which in turn translated into worse GvHD and relapse free survival (HR 1.13). Effects on GvL and GvHD appeared strongest in GvH-directed non-permissive mismatches. Our study results support the consideration of additional HLA-DPB1 mismatch parameters along with the established TCE3 matching algorithm for refinement of future donor selection. In particular, our findings suggest that DP non-permissiveness associated with two HLA-DPB1 mismatches or at least on highly expressed mismatched patient allotype should be avoided.

Randomized phase-II trial evaluating induction therapy with idarubicin and etoposide plus sequential or concurrent azacitidine and maintenance therapy with azacitidine

The aim of this randomized phase-II study was to evaluate the effect of substituting cytarabine by azacitidine in intensive induction therapy of patients with acute myeloid leukemia (AML). Patients were randomized to four induction schedules for two cycles: STANDARD (idarubicin, cytarabine, etoposide); and azacitidine given prior (PRIOR), concurrently (CONCURRENT), or after (AFTER) therapy with idarubicin and etoposide. Consolidation therapy consisted of allogeneic hematopoietic-cell transplantation or three courses of high-dose cytarabine followed by 2-year maintenance therapy with azacitidine in the azacitidine-arms. AML with CBFB-MYH11, RUNX1-RUNX1T1, mutated NPM1, and FLT3-ITD were excluded and accrued to genotype-specific trials. The primary end point was response to induction therapy. The statistical design was based on an optimal two-stage design applied for each arm separately. During the first stage, 104 patients (median age 62.6, range 18-82 years) were randomized; the study arms PRIOR and CONCURRENT were terminated early due to inefficacy. After randomization of 268 patients, all azacitidine-containing arms showed inferior response rates compared to STANDARD. Event-free and overall survival were significantly inferior in the azacitidine-containing arms compared to the standard arm (p < 0.001 and p = 0.03, respectively). The data from this trial do not support the substitution of cytarabine by azacitidine in intensive induction therapy.

DNMT3A mutant transcript levels persist in remission and do not predict outcome in patients with acute myeloid leukemia

We investigated the prognostic impact of minimal residual disease (MRD) monitoring in acute myeloid leukemia patients harboring DNA methyltransferase 3A-R882H/-R882C mutations (DNMT3A^mut). MRD was determined by real-time quantitative PCR (RQ-PCR) in 1494 samples of 181 DNMT3A^mut patients. At the time of diagnosis, DNMT3A^mut transcript levels did not correlate with presenting clinical characteristics and concurrent gene mutations as well as the survival end points. In Cox regression analyses, bone marrow (BM) DNMT3A^mut transcript levels (log10-transformed continuous variable) were not associated with the rate of relapse or death. DNMT3A^mut transcript levels were significantly higher in BM than in blood after induction I (P=0.01), induction II (P=0.05), consolidation I (P=0.004) and consolidation II (P=0.008). With regard to the clinically relevant MRD time points, after two cycles of induction and at the end of therapy, DNMT3A^mut transcript levels had no impact on the end point remission duration and overall survival. Of note, only a minority of the patients achieved RQ-PCR negativity, whereas most had constantly high DNMT3A^mut transcript levels, a finding which is consistent with the persistence of clonal hematopoiesis in hematological remission.

Prospective noninterventional study on peripheral blood stem cell mobilization in patients with relapsed lymphomas

High-dose chemotherapy followed by autologous stem cell transplantation (ASCT) to rescue hematopoiesis is considered standard care for patients with a relapsed chemosensitive lymphoma, but diagnosis of lymphoma has been a risk factor for poor mobilization in several studies. The aim of this prospective noninterventional clinical audit was to review the mobilization strategies used by EBMT centers in relapsed lymphoma and to evaluate their efficacy. Between 2010 and 2014, 275 patients with relapsed lymphoma from 30 EBMT centers were prospectively registered. Almost all patients were mobilized with chemotherapy plus G-CSF (96%), but there was a large variation in chemotherapy schedules. Thirty (11%) of them were poor mobilizers (<2 × 10⁶ CD 34+ cells/kg body weight) at the first mobilization. Poor mobilization was not associated with gender, age, bone marrow involvement at diagnosis, primary diagnosis, number of previous chemotherapy lines, previous radiotherapy or mobilization with G-CSF alone. The use of high dose cyclophosphamide alone was associated with mobilization failure (P = 0.0006), whereas the use of a platinum-containing regimen was associated with a good mobilization outcome (P = 0.013). Because failure rate is low, we can conclude from this study that PBSC mobilization failure in relapsed lymphomas is not an important problem in the EBMT centers.

ASXL1 mutations in younger adult patients with acute myeloid leukemia: a study by the German-Austrian Acute Myeloid Leukemia Study Group

We studied 1696 patients (18 to 61 years) with acute myeloid leukemia for ASXL1 mutations and identified these mutations in 103 (6.1%) patients. ASXL1 mutations were associated with older age (P<0.0001), male sex (P=0.041), secondary acute myeloid leukemia (P<0.0001), and lower values for bone marrow (P<0.0001) and circulating (P<0.0001) blasts. ASXL1 mutations occurred in all cytogenetic risk-groups; normal karyotype (40%), other intermediate-risk cytogenetics (26%), high-risk (24%) and low-risk (10%) cytogenetics. ASXL1 mutations were associated with RUNX1 (P<0.0001) and IDH2(R140) mutations (P=0.007), whereas there was an inverse correlation with NPM1 (P<0.0001), FLT3-ITD (P=0.0002), and DNMT3A (P=0.02) mutations. Patients with ASXL1 mutations had a lower complete remission rate (56% versus 74%; P=0.0002), and both inferior event-free survival (at 5 years: 15.9% versus 29.0%; P=0.02) and overall survival (at 5 years: 30.3% versus 45.7%; P=0.0004) compared to patients with wildtype ASXL1. In multivariable analyses, ASXL1 and RUNX1 mutation as a single variable did not have a significant impact on prognosis. However, we observed a significant interaction (P=0.04) for these mutations, in that patients with the genotype ASXL1(mutated)/RUNX1(mutated) had a higher risk of death (hazard ratio 1.8) compared to patients without this genotype. ASXL1 mutation, particularly in the context of a coexisting RUNX1 mutation, constitutes a strong adverse prognostic factor in acute myeloid leukemia.

T-cell reconstitution after allogeneic stem cell transplantation: assessment by measurement of the sjTREC/βTREC ratio and thymic naive T cells

The immune reconstitution after allogeneic hematopoietic stem cell transplantation comprises thymus-dependent and thymus-independent pathways. We wanted to improve the understanding of this complex process using two different measurements at definite checkpoints of T-cell neogenesis. We therefore assessed the thymus-dependent pathway by combining measurements of single joint T-cell receptor excision circles (sjTREC) and β T-cell receptor excision circles (βTREC) in an improved quantitative light-cycler hybridization polymerase chain reaction assay. In a subgroup of patients, we additionally assessed the proliferation kinetics of the CD31(+) thymic naïve cell population, which corresponds to recent thymic emigrants by six-color immunostaining. After the establishment of normal values in 22 healthy volunteers, we applied our polymerase chain reaction to 66 patients undergoing allogeneic hematopoietic stem cell transplantation at a median age of 44 years. It took more than 2 years after transplant to restore the pre-transplant thymic proliferation capacity. Only one third of the patients in our longitudinal study reached age-adjusted normal values for both sjTREC and βTREC at a median follow-up of 558 days, with acute graft-versus-host disease being the most prominent negative factor by univariate analysis. We observed several patterns of sjTREC and βTREC recovery suggesting different mechanisms of thymic damage in individual patients. In a comparison of CD31(+) thymic naïve cells between volunteers and patients after transplant we found a significantly higher peak proliferation rate within the latter population in the first year after transplantation. The combination of measurements of sjTREC and βTREC by our simplified polymerase chain reaction assay provides insight about the stage of T-cell development affected by different types of damage and may help to choose the correct therapeutic intervention. Besides the sole thymic T-cell neogenesis, proliferation within the CD31(+) thymic naïve cell compartment contributed to the replenishment of the naïve T-cell pool after transplantation.

Prognosis of patients with primary central nervous system lymphoma after high-dose chemotherapy followed by autologous stem cell transplantation

High-dose chemotherapy followed by autologous stem cell transplantation has been shown to be feasible and highly effective in newly diagnosed primary central nervous system lymphoma. In this retrospective multicenter study, we investigated prognosis and baseline risk factors in patients with primary central nervous system lymphoma who underwent this treatment approach. We retrospectively analyzed 105 immunocompetent patients with primary central nervous system lymphoma who underwent high-dose chemotherapy followed by autologous stem cell transplantation with or without whole brain radiotherapy as first-line consolidation treated at 12 German centers between 1997 and 2011. We estimated survival rates and investigated the impact of age, performance status, serum lactate dehydrogenase level, and deep brain involvement on overall and progression-free survival. Patients were additionally categorized into three prognostic groups according to the Memorial Sloan Kettering Cancer Center prognostic model. After a median follow up of 47 months, median progression-free survival and overall survival was reached after 85 and 121 months; 2- and 5-year survival rates were 82% and 79%, respectively. The Memorial Sloan Kettering Cancer Center prognostic model did not predict survival. Only age revealed some evidence of prognostic relevance. Overall response rate was 95%; of those patients with progressive disease before high-dose chemotherapy, 7 of 20 achieved ongoing complete remission after therapy without whole brain radiation therapy. Transplantation-associated mortality was 2.8%. High-dose chemotherapy followed by autologous stem cell transplantation is a highly effective and safe treatment modality for selected primary central nervous system lymphoma patients. Superiority compared to standard chemotherapy still warrants further investigation.

Cerebrospinal fluid pleocytosis: pitfalls and benefits of combined analysis using cytomorphology and flow cytometry

BACKGROUND

Cerebrospinal fluid samples with doubtful morphologic interpretation are a common problem in the workup of patients with clinical signs for leptomeningeal disease. The authors report on the combination of morphology and flow cytometry in the diagnosis of leptomeningeal disease in patients with radiological, clinical, or cytological findings suspicious for leukemia or lymphoma with spread into the cerebrospinal fluid.

METHODS

The authors defined a set of antibodies for flow cytometric analysis, which is capable of distinguishing between malignant and nonmalignant hematopoietic cells. One hundred twenty-seven cases were analyzed with both methods.

RESULTS

The additional application of flow cytometry resulted in an improvement of diagnostic reliability in 29 of 127 cases. Diagnostic sensitivity was raised from 73% (cytology) to 96% (flow cytometry), specificity from 94% to 97%, the positive predictive value from 88% to 96%, and the negative predictive value from 76% to 97%.

CONCLUSIONS

Because the appropriate selection of markers is crucial to successful analysis, the authors suggested a highly selected panel of antibodies for flow cytometry analysis of cerebrospinal fluid samples. The authors were able to demonstrate that leptomeningeal disease caused by leukemia or lymphoma can be diagnosed by flow cytometry and discriminated from reactive pleocytosis in most cases of doubtful morphology.

Neoplastic meningitis in patients with acute myeloid leukemia scheduled for allogeneic hematopoietic stem cell transplantation

We analyzed the frequency of neoplastic meningitis in patients with acute myeloid leukemia prior to allogeneic hematopoietic stem cell transplantation at our institution. Between 1996 and 2009, cerebrospinal fluid samples of 204 adult patients were examined during pre-transplant work-up for cell counts and, if abnormal, morphologically. We found blasts in cerebrospinal fluid samples of 17 patients with either persistent (n=9) or newly diagnosed (n=8) neoplastic meningitis. All patients proceeded to transplant. The proportion of patients with central nervous system involvement was significantly higher in patients with refractory disease at the time of transplantation compared with patients responding to prior systemic therapy (19% vs. 4.6%; P=0.003). Since most of the patients with central nervous system involvement were asymptomatic, cerebrospinal fluid evaluation should be considered at least in patients with refractory acute myeloid leukemia.

High-dose RHAMM-R3 peptide vaccination for patients with acute myeloid leukemia, myelodysplastic syndrome and multiple myeloma

BACKGROUND

Recently, 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 microg peptide.

DESIGN AND METHODS

Nine 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.

RESULTS

In 4 of 9 patients (44%) we detected positive immunological responses. These patients showed an increase of CD8(+)RHAMM-R3_tetramer(+)/CD45RA(+)/CCR7(-)/CD27(-)/CD28(-) 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 microg cohort.

CONCLUSIONS

High-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.

Nilotinib hampers the proliferation and function of CD8+ T lymphocytes through inhibition of T cell receptor signalling

The novel selective BCR-ABL Breakpoint cluster region – Abelson murine leukemia viral oncogene homolog 1 (BCR-AML) inhibitor nilotinib (AMN107) is a tyrosine kinase inhibitor that is more potent against leukaemia cells in vitro than imatinib. As nilotinib might be used in the context of allogeneic stem cell transplantation where CD8⁺ T lymphocytes play a pivotal role in the graft-versus-leukaemia (GVL) effect, we investigated effects of nilotinib on this lymphocyte subpopulation. Nilotinib inhibits phytohemagglutinin (PHA)-induced proliferation of CD8⁺T lymphocytes in vitro at therapeutically relevant concentrations (0.5–4 μM). The inhibition of CD8⁺ T lymphocytes specific for leukaemia or viral antigens through nilotinib was associated with a reduced expansion of antigen peptide specific CD8⁺ T lymphocytes and with a decreased release of interferon—γ and granzyme B by these cells as analysed by flow cytometry and enzyme-linked immunospot (ELISPOT) assays. The inhibitory effect caused by nilotinib was two times stronger than by imatinib. These effects were mediated through the inhibition of the phosphorylation of ZAP-70, Lck and ERK 1/2 and the NF-κβ signalling transduction pathway. Taken together, we observed a strong suppressive impact of nilotinib on the CD8⁺ T lymphocyte function which should be considered carefully in the framework of allogeneic stem cell transplantation or other T cell based immunotherapies.

[Female patient with organic psychosyndrome and neurological focal signs after immunosuppressant therapy]

Cerebral toxoplasmosis nearly exclusively affects immunodeficient or immunocompromised patients. Mostly, it is a reactivation of latent toxoplasmosis. The pathogens, persisting in the reticuloendothelial system of heart and skeletal muscle cells, are causing a multifocal necrotizing encephalitis. The characteristic clinical features are organic psychosyndrome and focal neurological signs such as monoparesis, hemiparesis, aphasia, or seizures. Here we describe a 56-years-old patient who developed cerebral toxoplasmosis after receiving stem-cell transplantation treatment for acute myeloic leukemia, and we discuss the clinical features, differential diagnoses and therapeutic strategies.

RHAMM (CD168) is overexpressed on the protein level and may constitute an immunogenic antigen in advanced prostate cancer disease

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Introduction: Treatment options for early stage prostate cancer are well defined, and localized prostate cancer can be cured by several strategies. However therapeutic outcome in advanced tumor stages is still disappointing. One approach is to deliver targeted therapy based on identified human tumor antigens, specifically expressed in neoplastic tissue and recognised by CD4/CD8 T-cells or antibodies. Materials and Methods: We employed serological identification of antigens by recombinant expression cloning (SEREX) and data mining in SEREX related databases to identify potential immunological target structures. Consequently, candidate antigens were screened by DNA microarrays consisting of approximately 20K genes, designed to profile benign and malignant prostate tissues. Genes overexpressed on the cDNA level were evaluated on the protein level by tissue microarrays representing various disease stages including about 900 tissue cores. Protein expression was measured by the Chromavision system. Results: Ten of the targets identified by SEREX and data mining showed a significant overexpression on the 20k cDNA array in localized prostate cancer compared to benign prostatic hyperplasia and in metastases compared to localized prostate cancer. One gene which has been identified earlier as an immunogenic antigen in leukemia by our group, CD168, showed a highly significant overexpression in prostate cancer metastases compared to localized disease (p=0.007). On the protein level CD168 was highest in metastatic tissue samples and significantly higher in neoplastic localized disease compared to benign tissue (p=0.03). High CD168 expression had an association to clinical parameters known to be associated with better clinical outcome. Patients with high CD168 expression in the primaries had a significantly lower risk for biochemical failure (log rank p=0.023; RR:0.621). In cell culture experiments, the number of viable cells was reduced in blocking experiments using hormone sensitive (LNCaP) and hormone insensitive metastatic (PC3 and DU 145) prostate cancer cell lines. Conclusion: Acknowledging the proven immunogenic effects of CD168 in leukemia, this antigen is an intriguing therapeutic target in advanced prostate cancer disease.

No significant financial relationships to disclose.

Imatinib impairs CD8+ T lymphocytes specifically directed against the leukemia-associated antigen RHAMM/CD168 in vitro

The Bcr-Abl tyrosine kinase inhibitor imatinib mesylate is highly effective in the front-line treatment of chronic myeloid leukemia (CML) and is increasingly used in patients with residual disease or relapse after allogeneic stem cell transplantation (allo-SCT). Since an impairment of anti-viral CD8+ T-lymphocyte function by imatinib has been described, we question whether imatinib also affects specific anti-leukemic CD8+ T lymphocytes generated from the peripheral blood of healthy donors, and of CML patients after allo-SCT. Here, we assessed CD8+ T-cell expansion and function from healthy donors and patients with CML. The release of IFN-gamma and granzyme B by CD8+ T-lymphocytes specific for R3, a recently described T-cell epitope peptide derived from a leukemia-associated antigen designated RHAMM/CD168 (receptor for hyaluronic acid mediated motility), was inhibited by imatinib in a dose-dependent fashion (range: 1-25 microM). These T cells were able to lyse cognate peptide labeled T2 cells and CD34+ CML progenitor cells. This lysis was inhibited by imatinib. The inhibitory effect was not associated with an increased rate of apoptosis of T cells and reversible after removal of imatinib. In the light of these findings, clinical administration of imatinib might result in the reduction of efficacy of the graft-versus-leukemia effect or other T-cell-based immunotherapies.

Reduced-intensity conditioning followed by T-cell depleted allogeneic stem cell transplantation for patients with chronic myeloid leukaemia and minimal residual disease at the time of transplant: high risk of molecular relapse

A pilot trial was initiated for chronic myeloid leukaemia patients, which employed imatinib for remission induction, followed by reduced-intensity conditioning and an in vivo T-cell depleted graft. Out of nine patients, six experienced a molecular relapse and one patient had a haematological relapse at a median interval of 5 months after transplantation. Five relapsing patients achieved a 2nd molecular remission after treatment with either donor lymphocyte infusions (n = 4) or imatinib (n = 1). Two of nine patients died due to infectious complications. The probability of survival 2 years after transplant was 74% (95% CI 42-100%).

Translation molekularer Zusammenhänge in die klinische Anwendung

For patients with metastatic renal cell cancer (RCC), therapeutic options after cytokine failure are rather limited. There is a considerable need to identify new substances for systemic therapy. Due to upregulation after the loss of a functional von Hippel Lindau gene product, the vascular endothelial growth factor (VEGF) pathway is a promising target for a molecular based therapy. Over the last few years, therapeutic agents have been developed which inhibit this pathway at various levels. Here, we provide an overview of the molecular background and currently used drugs which have entered clinical trials in the setting of metastatic RCC disease. Until now, the results from early clinical trials are very promising, however, the best schedule, dosage, potential combination regimens, as well as long time efficacy, are still to be determined.

Bone marrow transplantation nephropathy after an intensified conditioning regimen with radioimmunotherapy and allogeneic stem cell transplantation

Intensification of the conditioning regimen with a radioactively labeled anti-CD66 antibody is feasible before allogeneic stem cell transplantation. The use of radioimmunotherapy may deliver a significant dose of radiation to the kidneys. We therefore studied the incidence and clinical picture of bone marrow transplantation (BMT) nephropathy in our patients receiving radioimmunotherapy before allogeneic stem cell transplantation.

METHODS

This study was a clinical trial of 114 consecutive patients who received conditioning with a radiolabeled anti-CD66 antibody-188Re (n = 93) or 90Y (n = 21)-between 1998 and 2003.

RESULTS

Although BMT nephropathy has developed in none of the patients in the [90Y]anti-CD66 group, 6 of 93 patients receiving [188Re]anti-CD66 presented with signs of BMT nephropathy at a median of 11.5 mo after stem cell transplantation. The absorbed renal dose was significantly lower in the 90Y group (4 vs. 7 Gy, P < 0.0001). Of the patients receiving [188Re]anti-CD66 who are alive, BMT nephropathy developed in 19% (6/32). Five of 6 patients with BMT nephropathy received total-body irradiation. The patients presented with elevated serum creatinine, proteinuria, anemia, hypertension, and signs of microangiopathy. All 6 patients in whom BMT nephropathy has developed are alive at a median follow-up of 58 mo after stem cell transplantation, and 1 patient has entered a dialysis program.

CONCLUSION

BMT nephropathy appears to be a significant problem after allogeneic stem cell transplantation with intensified conditioning using the 188Re-labeled anti-CD66 applied in this study, particularly when combined with total-body irradiation.

188Re or 90Y-labelled anti-CD66 antibody as part of a dose-reduced conditioning regimen for patients with acute leukaemia or myelodysplastic syndrome over the age of 55: results of a phase I-II study

In a phase I-II study for patients aged 55-65 years, we employed radioimmunotherapy using an anti-CD-66 antibody as part of a dose-reduced conditioning regimen, which was followed by a T-cell-depleted graft. 20 patients with a median age of 63 years suffering from acute leukaemia (n=17) or myelodysplastic syndrome (n=3) received the antibody labelled either with 188Rhenium (n=8) or with 90Yttrium (n=12) during conditioning. Radioimmunotherapy provided a mean dose of 21.9 (+/-8.4) Gy to the bone marrow with a significantly higher dose when 90Yttrium was used. Additional conditioning was fludarabine-based plus anti-thymocyte globulin in matched related donor transplants (n=11), or plus melphalan in matched unrelated donor transplants (n=9). Regimen-related toxicity was low, with two patients developing three episodes of grade III organ toxicity. All patients engrafted, grade II-IV acute graft-versus-host disease (GvHD) was observed in one patient (5%) and chronic GvHD in three patients (15%). The cumulative incidence of non-relapse mortality was 25%, the cumulative incidence of relapse 55%. The probability of survival was estimated to be 70% at 1 year and 52% at 2 years post-transplant, although no plateau was reached afterwards. In conclusion, radioimmunotherapy using the anti-CD66 antibody was feasible and safe in our elderly patient group and provided a high marrow dose.

Dendritic cells generated from acute myeloid leukemia (AML) blasts maintain the expression of immunogenic leukemia associated antigens

Recently, the focus is on new specific immunotherapies for AML such as cellular therapies employing dendritic cells (DCs) generated from AML blasts. AML-DCs express constitutionally leukemia-associated antigens (LAAs) present in AML blasts they are generated from. Here we investigated whether the generation of AML-DCs would alter the expression level of LAAs. Moreover, we evaluated the presence of HLA and costimulatory molecules on AML blasts versus AML-DCs. Quantitative real-time polymerase chain reaction (PCR) was performed for the following LAAs: preferentially expressed antigen in melanoma (PRAME), the receptor for hyaluronic acid mediated motility (RHAMM/CD168), Wilms' tumor gene 1 (WT-1) and proteinase 3. The expression of HLA-ABC, HLA-DR, CD40, CD80, CD83 and CD86 was evaluated by flow cytometry. RHAMM protein expression was evaluated by immunocytochemistry, recognition of AML-DCs by PRAME epitope-specific T cells was evaluated in a chromium-release assay. Quantitative real-time PCR for AML-DCs versus AML blasts showed an alteration in mRNA expression of LAAs. An elevated PCR signal for PRAME was detected in 7/12 AML-DC preparations. 6/12 AML-DC preparations showed a significant upregulation of the PCR signal for RHAMM. A stronger WT-1 and proteinase-3 signal was observed in PCR for only 2/12 and 1/12 AML-DCs , respectively. All preparations showed a strong expression of at least one of the LAAs examined. As demonstrated by flow cytometry, AML-DCs strongly upregulated costimulatory molecules like CD40 and CD80 in comparison with AML blasts. AML-DCs tested positive for RHAMM protein. PRAME positive AML-DCs were recognized by specific T cells. AML-DCs might constitute a powerful tool in immunotherapy for AML. Real-time PCR allows a quick and quantitative assessment of immunologically relevant LAA expression with only 10(5) DCs and might be helpful for the decision whether the AML-DC vaccination strategy is favourable or not.

Identification and characterization of epitopes of the receptor for hyaluronic acid-mediated motility (RHAMM/CD168) recognized by CD8+ T cells of HLA-A2-positive patients with acute myeloid leukemia

The receptor for hyaluronic acid-mediated motility (RHAMM/CD168) has been described as a leukemia-associated antigen. To define T-cell epitopes of RHAMM/CD168 toward specific immunotherapies for acute myeloid leukemia (AML), 10 potential HLA-A2-binding RHAMM/CD168 peptides (R1 to R10) were synthesized based on computer algorithms and screened by enzyme-linked immunospot (ELISPOT) analysis using CD8+ T cells isolated from peripheral blood (PB) of patients with AML and healthy donors. We found that CD8+ cells from 7 of 13 (54%) patients with AML presensitized with peptides R3 (ILSLELMKL) or R5 (SLEENIVIL) specifically recognized T2 cells pulsed with R3 (39%) or R5 (15%) peptide. In contrast, only 4 of 21 (19%) healthy volunteers had CD8+ cells reactive with R3- or R5-pulsed T2 cells after presensitization. The presence of R3 peptide-specific effector T cells in the peripheral blood of patients with AML could be confirmed by staining as HLA-A2/R3 peptide tetramer+ CCR7-CD45RA+ cells. In chromium-51 release assays, peptide-primed CD8+ T cells from patients with AML were able to lyse RHAMM/CD168 peptide-pulsed T2 cells, AML blasts, and dendritic cells generated thereof (AML DCs). Transfection of COS7 cells with RHAMM/CD168 cDNA revealed that peptides R3 and R5 are naturally processed epitopes of RHAMM/CD168 that are presented in an HLA-A2-restricted manner. In summary, RHAMM/CD168 is a promising target for immunotherapies in patients with AML, and we have therefore initiated a clinical vaccination trial with R3 peptide. Because RHAMM/CD168 is also expressed in various other hematologic malignancies and solid tumors, vaccines targeting this antigen may have even wider application.

CD34 cell selection of peripheral blood progenitor cells using the CliniMACS device for allogeneic transplantation: clinical results in 102 patients

The present study investigated the effects of CD34(+) cell selection in 102 patients using the CliniMACS device. Patients were at high risk for the development of graft versus host disease (GvHD) because of age, or the use of a haploidentical, mismatched or unrelated donor (UD). The median age of the patients was 44 years. The CliniMACS procedure yielded 8.0 x 10(6) CD34(+) cells/kg and the number of residual T cells was 1.3 x 10(4)/kg (median). The median follow up was 20.6 months. The probability of graft failure was 7%. The rate of acute GvHD was low (compatible family donors 10%, UDs 17%, and haploidentical donors 26%) with no patient enduring more than grade II disease. The cumulative incidence of chronic GvHD at the median follow up after transplant was 15% for the compatible family donor group, 40% for the UD group and 78% in the group transplanted from a haploidentical donor Treatment failure was mainly because of transplant-related mortality, especially aspergillus infection, and not due to relapse. The probability of disease-free survival, stratified for the risk of treatment failure, was 27% for the high risk, 46% for the intermediate risk and 83% for the low risk group.

Simultaneous expression of T-cell activating antigens in renal cell carcinoma: implications for specific immunotherapy

PURPOSE

The activation of antigen specific T cells by tumor associated antigens (TAA) might be a promising treatment strategy for patients with renal cell carcinoma (RCC). We analyzed TAA expression in patients with RCC as well as the prevalence of fitting HLA phenotypes and calculated the percent of patients eligible for peptide vaccination trials.

MATERIALS AND METHODS

A total of 41 RCC samples from primary tumors were analyzed for TAA expression by reverse transcriptase-polymerase chain reaction. Genes of interest were MAGE-1, MAGE-3, G250 and PRAME since peptides derived from these genes have been shown to activate antigen specific cytotoxic T lymphocytes. Results were combined with data on the HLA gene and haplotype frequencies in the German population as an example of a white population.

RESULTS

Tumor specific expression of at least 1 T-cell activating antigen was observed in all patients. Of the patients 80% expressed 2 or more TAAs simultaneously. HLA molecules suitable for presentation of the respective antigens were calculated to be expressed in 51% to 85% of white German patients. These results mirror with only minor variations most of the white populations in Europe and North America.

CONCLUSIONS

We noted that T-cell activating tumor associated antigens are frequently expressed in patients with RCC. Based on HLA expression analysis in a white population at least 30% of patients with RCC are eligible for monovalent specific immunotherapy and 41% are eligible for polyvalent specific immunotherapy. These data are a rational basis for future prospective vaccination trials in patients with RCC.

mRNA expression of leukemia-associated antigens in patients with acute myeloid leukemia for the development of specific immunotherapies

Specific immunotherapies for patients with acute myeloid leukemia (AML) using leukemia-associated antigens (LAA) as target structures might be a therapeutic option to enhance the graft-vs.-leukemia effect observed after allogeneic stem cell transplantation or to prolong a complete remission (CR) achieved by chemotherapy. Significant mRNA expression of LAA is a prerequisite for such immunotherapies. Here, previously characterized antigens associated with solid tumors (TAA) and newly characterized LAA were investigated for their expression in up to 60 AML patients and in leukemia cell lines. To investigate their specificity for leukemic blasts, the mRNA expression was also characterized in PBMN and CD34 positive cells of healthy volunteers and in a panel of normal tissues. The following antigens showed high mRNA expression in AML patients: MPP11 was detected in 43/50 (86%), RHAMM in 35/50 (70%), WT1 in 40/60 (67%), PRAME in 32/50 (64%), G250 in 18/35 (51%), hTERT in 7/25 (28%) and BAGE in 8/30 (27%) of AML patients. Real-time RT-PCR showed a tumor-specific expression of the antigens BAGE, G250 and hTERT, as well as highly tumor-restricted expression for RHAMM, PRAME and WT1. The antigen MPP11 was overexpressed. These antigens might be candidates for immunotherapies of leukemia patients and, because of their simultaneous expression, also for polyvalent vaccines.

Characterization of several leukemia-associated antigens inducing humoral immune responses in acute and chronic myeloid leukemia

To design a specific immunotherapy for leukemia patients, the identification of leukemia-associated antigens (LAAs) is a pivotal step. Antileukemic effects after hematopoetic stem cell transplantation for myeloid leukemias are observed and might be related to the recognition of LAAs. Using the serological screening of an expression library (SEREX) of K562 cells, we identified 16 different clones encoding LAAs eliciting a humoral immune response, among them the heat shock proteins HSJ2 and HSP70, the M-phase phosphoprotein 11 (MPP11), the BRCA1-associated protein (BRAP), the Jkappa recombination binding protein (RBPJkappa) and the receptor for hyaluronic acid mediated motility (RHAMM). Serological responses to MPP11 were observed in 7/19 (37%) of patients with acute myeloid leukemia (AML) and 6/16 (38%) of patients with chronic myeloid leukemia (CML), but not in healthy volunteers (0/20). IgG antibodies directed against MPP11 were also detected in 25-50% of the sera of patients with solid tumors such as melanoma, renal cell, ovarian and breast carcinoma. mRNA expression of MPP11 was detected in 20/20 AML patients and 7/10 patients with CML. In normal tissues, strong mRNA expression of MPP11 was only detected in testis. By real-time PCR, we detected upregulation of MPP11 in leukemic blasts. Simultaneous humoral immune responses to 2 or more of the 16 LAAs identified here was observed, suggesting the feasibility of a polyvalent vaccination as an option for immunotherapies in leukemia patients.

Reconstitution of CD40 and CD80 in dendritic cells generated from blasts of patients with acute myeloid leukemia

Acute myeloid leukemia (AML) is a clonal disease of hematopoiesis with poor clinical outcome despite recent improvements in chemotherapy and stem cell transplantation regimens. Immunotherapy with dendritic cells (DCs) eliciting specific T cell responses to leukemia-associated antigens (LAAs) might be a therapeutic option. DCs must express HLA class I/II molecules and the costimulatory molecules CD40, CD80 and CD86 to effectively activate T cells for the subsequent lysis of leukemic blasts. The expression of these antigens on DCs generated from 15 AML patients (AML-DCs) and on DCs generated from 15 healthy volunteers (HV-DCs) was analyzed by FACS. All DCs displayed the typical morphology and tested negative for B, T and NK cell markers. The sustained mRNA expression of LAAs such as PRAME, RHAMM or WT-1 proved that the AML-DCs originated from AML blasts. Compared with AML blasts, the expression of CD40, CD80, CD86 and HLA-DR was upregulated during DC culture to a median of 80-98% on AML-DCs. HLA-ABC was preserved on AML-DCs (median 95%). Expression of CD40, CD80 and CD83 remained lower on AML-DCs than on HV-DCs. AML-DCs express at least one LAA and strongly express HLA and costimulatory molecules, the prerequisites for eliciting T cell responses. AML-DCs may play a role in vaccine-based immunotherapies for AML patients.

Expression of human leucocyte antigens and co-stimulatory molecules on blasts of patients with acute myeloid leukaemia

Recently, leukaemia-associated antigens (LAA) recognized by T lymphocytes, such as Wilm's tumour-1 (WT-1) or pathogenesis-related protein-1 (PR-1), have been identified. For immunotherapies that employ antigen peptides, either alone or pulsed on dendritic cells (DC), the expression of human leucocyte antigen (HLA) molecules on the targeted leukaemic blasts (LB) is crucial. The co-stimulatory molecules CD80 and CD86 give the secondary signal to T lymphocytes that is necessary for the lysis of leukaemia cells, and CD40 enhances the efficacy of antigen presentation. Here, the expression of HLA-ABC, HLA-A2, HLA-DR, CD40, CD80 and CD86 was flow cytometrically examined in blood samples from 24 healthy volunteers (HV), 24 patients with newly diagnosed acute myeloid leukaemia (AML) and five patients with relapsed AML. The expression of HLA-ABC, CD40, CD80 and CD86 was significantly reduced on LB in comparison with monocytes of HV. HLA-A2 and HLA-DR expression was similar on LB and on monocytes of HV. In AML patients, the expression of HLA and CD86 molecules was significantly higher on LB than on CD33/CD34-negative monocytes. CD40 and CD80 molecules were deficient on AML blasts. The preservation of HLA molecules and CD86 on LB of the majority of AML patients at the time of diagnosis and even at relapse of the disease are prerequisites for LAA-targeted immunotherapies in these patients.

Receptor for hyaluronan acid-mediated motility (RHAMM) is a new immunogenic leukemia-associated antigen in acute and chronic myeloid leukemia

OBJECTIVE

Identification of leukemia-associated antigens (LAA) eliciting an immune response in patients is a prerequisite for specific immunotherapy of leukemias. To identify new LAA, we used the method of serologic screening of cDNA expression libraries (SEREX).

MATERIALS AND METHODS

A SEREX library of the cell line K562 was subjected to allogeneic screening with sera from patients with acute myeloid leukemia (AML) or chronic myeloid leukemia (CML) vs sera from healthy volunteers.

RESULTS

The receptor for hyaluronan acid-mediated motility (RHAMM) involved in cell growth and metastasis was identified as a new LAA. Serologic responses to RHAMM were observed in patients with AML (42%), CML (31%), melanoma (83%), renal cell carcinoma (40%), breast cancer (67%), and ovarian carcinoma (50%), but not in HV or patients with autoimmune diseases. RHAMM mRNA was detectable in peripheral blood mononuclear cells (PBMN) of 60% of newly diagnosed AML patients. Western blotting stained positive for RHAMM protein in 70% of AML patients. mRNA expression of RHAMM also was found in patients with CML (40%), renal cell carcinoma (73%), breast carcinoma (60%), and ovarian carcinoma (50%). In melanoma, RHAMM mRNA expression was detected in metastases (80%) but not in primary tumors. RHAMM is differentially expressed: significant mRNA expression was not found in normal tissues, except from testis, placenta, and thymus, or in PBMN- and CD34-separated cell samples of healthy volunteers.

CONCLUSIONS

RHAMM is an immunogenic antigen in leukemias and solid tumors and might be a potential target structure for cellular immunotherapies and antibody therapies.

[Specific cellular immunotherapy of renal cell carcinoma. Current status and prospects]

Renal cell carcinoma (RCC) is susceptible to immunomodulating therapies. This is proven by clinical responses to unspecific immunotherapy with cytokines. Understanding the mechanisms of antigen presentation and recognition by T cells enables us to expand T-cell clones which are capable of recognizing specific tumor-associated antigens (TAA). The use of dendritic cells (DC) in specific cellular immunotherapy could be beneficial because of their outstanding properties in antigen presentation and T-cell costimulation. In order to circumvent the escape of some tumor cells under T-cell pressure, polyvalent vaccination strategies should be developed. This goal can be achieved by either pulsing respective transfecting DC with tumor cell lysates, RNA or DNA libraries, or a pool of peptide antigens. Careful monitoring of the elicited T-cell response and quality assurance (GMP and GCP) are mandatory to establish a rationale for specific immunotherapy against RCC and to bring it from the bench to the bedside.

Quantitative assessment of the expression of melanoma-associated antigens by non-competitive reverse transcription polymerase chain reaction

The assessment of tumor-associated antigens (TAA) recognized by T lymphocytes is a prerequisite for diagnosis and immunotherapy of melanoma. Different reverse transcription-polymerase chain reaction (RT-PCR) protocols allowing the quantification of the TAA mRNA expression in the solid tumor or the detection of circulating melanoma cells have been described. We have recently shown a positive correlation between the amount of specific product formed by RT-PCR and the staining intensity in immunohistochemical analysis of the corresponding sample. Here we describe a quantification procedure based on the direct digitization of the PCR products after separation on ethidium bromide-stained agarose gels, followed by computer-assisted densitometry. To standardize our method, we examined the linear range of the densitometric quantification procedure as reflected by the correlation of signal intensity to the amount of the corresponding DNA. As an internal measure for the so-termed cDNA in the different samples after RNA isolation and reverse transcription, a beta-actin PCR was introduced. Subsequently, we chose four sets of primers for the melanoma-associated antigens MAGE1, tyrosinase, Melan A/MART-1 and gp100/Pmel17 and performed PCR analysis over a range of cycle numbers. In each case, the amplification rate remained constant up to at least 26 cycles under the respective conditions. Plotting the logarithm of the amount of product against the cycle number yields a slope that equals the logarithm of the amplification rate. The amount of starting material can be determined from the intercept with the ordinate. In summary, the method introduced in the present work allows the quantification of TAA in melanoma which might be important for the monitoring of disease. Technically the method is sound and sensitive, avoids post-PCR manipulations and can be performed with the standard equipment of a molecular biology laboratory. It can be applied also to other solid tumors and leukemias.

Fatal outcome in a patient developing Epstein-Barr virus-associated lymphoproliferative disorder (EBV-LPD) without measurable disease

A 51-year-old female patient in the first chronic phase of CML received an allogeneic PBSCT from a matched unrelated donor. The transplant was manipulated by CD34+ cell selection. On day +193 after transplantation the patient was readmitted to the hospital with recurrent fever of unknown origin and cough. Clinical, radiographic and sonographic evaluation revealed no characteristic findings besides a mild splenomegaly. Screening for EBV, CMV, RSV and HSV did not indicate an active infection. On day +203 the patient developed generalized seizures, respiratory failure and died within 24 h in multiorgan failure. The macroscopic postmortem was still not enlightening; the histological examination however, demonstrated diffuse organ infiltration by monoclonal lymphoblastoid cells due to EBV-LPD.