ALBERT

Description: We hypothesized that after allogeneic hematopoietic stem cell transplant (HSCT), GvHD-affected tissues harbor expanded “immunodominant” T-cell clones, and characterization of these clones can be used to develop markers of disease. A multiplex PCR was used to detect T-cell receptor variable beta (VB) chain rearrangements in target tissue. Molecular analysis of the amplified VB CDR3 sequences allowed for identification and quantitation of putative disease-associated “clonotypes” and for the development of clone-specific PCR. We studied 5 HSCT patients for the presence of signature clonotypes in 10 skin biopsies taken during diagnostic GvHD work-up. Size distribution analysis of VB PCR products showed a skewed peak pattern in 9 biopsies; immunodominant clones (per definition frequency ≥30%) were detected in 6/7 biopsies with histologically confirmed GvHD, consistent with the presence of expanded clonotypes and the oligoclonal nature of the tissue-specific alloresponse. Immunodominant clones were also found in 2 of 3 biopsies not diagnostic for GvHD but obtained based on strong clinical suspicion, raising the possibility that they were associated with early evolving GvHD not distinguishable by histology. For example, when serial skin biopsies were analyzed, a GvHD-positive post-transplant d63 biopsy contained an immunodominant clone (frequency 60%), which was also detected in a subsequent biopsy positive for GvHD (frequency 33%). Similar results were seen in another patient, in whom serial biopsies taken on d214 (not diagnostic) and d217 (GvHD-positive) showed an identical immunodominant clone, not present in a d13 GVHD-negative biopsy. This finding suggests that the d214 biopsy might have contained early GvHD that was not detectable morphologically. In a patient who rejected an initial MUD graft (Tx 1) and then received a MUD SCT (Tx 2) from a different, unrelated donor, immunodominant clones were identified in GvHD-positive biopsies following each transplant, that were distinct for each graft. To examine whether immunodominant clonotypes derived from biopsies could be used as markers of disease, clonotypic PCR was developed for an immunodominant biopsy-derived clonotype for each transplant. The Tx 1 clonotype was detected in blood and skin following Tx 1, but not in tissue or blood taken after Tx 2. Specificity and correct size of the clonotypic PCR product were confirmed by both Genescan analysis and sequencing. Clonotypic PCR designed for an immunodominant clonotype from the Tx 2 donor detected the putative allospecific clonotype in serial samples after the second engraftment. Neither clonotype could be found in either donor, indicating that the disease-associated clones expanded to detectable levels following transplant. These results indicate that clonotypic PCR can distinguish distinct GvHD-associated clonotypes from different donors in both blood and tissue following transplant. Monitoring of the relative frequency of disease-associated clones in recipient blood indicated a significant peripheral expansion of disease-associated clones at the time of active GvHD. Our results demonstrate an efficient method for identification of disease-associated clonotypic markers, which can be used to aid diagnosis and monitoring of GvHD.

Description: LBH589 is a novel HDAC inhibitor which activates p21 and inhibits proliferation and induces apoptosis in tumor cell lines at nanomolar concentrations. In this study, LBH589 was administered IV as a 30-minute infusion on days 1–7 of a 21 day cycle. Fourteen pts. (median 61 years [range 42–87], performance status 0 (2 pts) or 1 (12 pts), de novo AML (2 pts), relapsed /refractory AML (10 pts), refractory ALL (1 pt), MDS (RAEB) (1 pt) have been treated at dose levels (mg/m2): 4.8 (3 pts), 7.2 (3 pts), 9.0 (1 pt), 11.5 (2 pts), 14.0 (5 pts). Four DLT’s (G3 QTcF prolongation) have been observed − 3 at 14.0 mg/m2 and one at 11.5 mg/m2 (a total of 357 ECG’s were performed during the study). One patient treated at 14.0 mg/m2 died of pulmonary hemmorhage resulting from sepsis while on study. Treatment with LBH589 as well as the patient’s underlying disease (MDS) were considered a contributing factors to the sepsis. A white cell differentiation syndrome (which was sucessfully treated with high-dose steroids) was observed in one patient with refractory AML treated at 14.0 mg/m2. Other LBH589-related toxicities included: Grade 1 ST-T wave abnormality, palpitations, hypokalemia; Grade 2 diarrhea, nausea, vomiting, loss of appetite, headache, atrial fibrillation, and QT prolongation. In 9 of 12 patients (2 patients were aleukemic), treatment with LBH589 resulted in reductions in peripheral blasts, WBC and platelets during treatment. Counts rebounded following the 7-day treatment period (generally by day 15). Bone marrow blast counts generally continued to increase during treatment. The levels of histone acetylation in bone marrow and peripheral blood cells were measured using quantitative flow cytometry and antibodies against histones H2B and H3. The median acetylation of histones H2B and H3 in CD34+ cells increased on therapy from 4463 to 17185 and from 11540 to 66224, respectively. Despite this increase in histone acetylation a significant change in apoptosis (measured by annexin V or mitochondrial potential) or proliferation (measured by BrdU incorporation) in CD34+ cells was not demonstrated. However, peripheral blood lymphocytes showed significant increase in apoptosis on day 7 as compared with the levels of apoptosis before therapy. PK samples were collected on days 1 and 7 of cycle 1 and analyzed using a noncompartmental analysis. Plasma LBH589 concentrations were determined using HPLC/MS/MS assay. AUC increased proportionally with dose and mean AUCs (0–24h) were 139.47, 131.46, 189.12, and 344.28 ng.h/mL, respectively, for 4.8, 7.2, 9.0, and 14.0 mg/M2 dose levels on Day 1. Terminal half-life was approximately 11 hrs. LBH589 given IV appears well tolerated at doses below 11.5 mg/m2 with consistent transient antileukemic and PD effects.

Description: Invasive aspergillosis is still a life-threatening complication, in particular in patients after allogeneic hematopoietic stem cell transplantation (HSCT). Whereas prolonged neutropenia is a well established risk factor for invasive fungal disease, there is a growing body of evidence that T-cells also play an important role in the immunological response to Aspergillus species. Since invasive aspergillosis often occurs during the phase of postengraftment, which is characterized by impaired cell-mediated immunity, Aspergillus-specific T-cells could be a potential therapeutic target in these patients. We therefore analyzed in a first step the response of T-cells to several potential antigens of Aspergillus fumigatus by means of 3H-thymidine incorporation assay. In order to generate Aspergillus-specific T-cells, the antigens with the highest proliferation indices (EC-SAB and 90 kDa catalase) were used to stimulate 1.0 x 108 mononuclear cells from healthy donors. The activated T-cells were isolated on the following day using the IFN-γ secretion assay (Miltenyi Biotec, Germany) and then expanded for 14 days. Intracellular cytokine analysis of EC-SAB generated cell lines (n=7) revealed a significant IFN-γ secretion by 13.6%±2.3 of CD4+ cells (seven out of seven tested cell lines) and an Aspergillus-specific IL-2 secretion by 6.5%±1.9 of CD4+ cells (three out of three tested cell lines), which supports the TH1 response of the generated cells to Aspergillus antigen. In contrast to EC-SAB generated T-cell populations, all three cell lines which were generated with 90 kDa catalase were not informative. Further analysis showed that restimulation with EC-SAB induced a strong proliferation of EC-SAB generated T-cell populations (all three populations tested), whereas alloreactivity was unaffected. The number of these cells could be expanded within 14 days up to 20fold using OKT-3, IL-2 and feeder cells. Currently, we investigate the impact of these Aspergillus-specific cell populations in the defense to different species of Aspergillus. Our preliminary results suggest that Aspergillus-specific T-cells could be an interesting option in prophylaxis and therapy of invasive aspergillosis in patients undergoing HSCT.

Description: T-cell acute lymphoblastic leukemia (T-ALL) accounts for 25% of adult ALL and is characterised by specific clinical and biologic features such as phenotype with early (cyCD3+,CD7+) (E-T), thymic (CD1a+) ) (Thy-T) and mature T-ALL (M-T) (sCD3+). The formerly poor prognosis of T-ALL was more recently improved in some studies albeit not in all, even not in childhood ALL. Patients: To improve outcome of T-ALL the German Multicenter Study Group for Adult ALL initiated two consecutive studies with subtype adapted therapies. 503 T-ALL pts were recruited between 4/93 and 10/03. The median age was 30 (15–55)yrs, 75% were male, 66% had mediastinal tumor (MedTu), 24% WBC 〉 100.000 and 7% CNS involvement with subtypes as follows: 53% Thy-T, 26% E-T and 21% M-T. Study Design: In Study 05/93 all T-ALL pts were treated uniformly with 8drug induction incl. prophylactic CNS (24 Gy) (CNSRAD) and proph. mediastinal (24 Gy) irradiation (MEDRAD) followed by 7x consolidation (HDAC/MITOX, HDMTX/ASP, reinduction, 2xVM26/AC, 2xCYCLO/AC) and maintenance (6MP/MTX). In Study 06/99 treatment of T-ALL was risk adapted with a shortened, intensified 8drug induction (CNSRAD in all but MEDRAD only in pts with residual MedTu after induction) followed by consolidation I (HDAC/HDMTX/VP16). Thy-T was then treated as standard risk with 6x consolidation (3xHDMTX/ASP,reinduction,VM26/AC,CYCLO/AC). E-T and M-T were considered as high risk and scheduled for stem cell transplantation (SCT) in CR1. Results: In Study 05/93 the CR rate in 291 pts was 89% (94%, 73% and 90% for Thy-T, E-T and M-T; p=.0006) and even 97% for Thy-T in adolescents (15–25 yrs) . Overall 4% failed to achieve CR and 7% died in induction. The probability of continuous CR (CCR) at 5 yrs was overall 53% and 64% for Thy-T, but only 30% (p

Description: Despite the major peak of ALL in childhood the incidence also increases in the elderly beyond 50 yrs. Outcome of these elderly ALL pts is very poor. In a survey including 12 studies with 370 pts (50–88 yrs) the mean CR rate was 50% and the rate of continuous CR (CCR) 13%. Also in a first prospective pilot study of the German Multicenter Study Group for Adult ALL (GMALL) for elderly ALL pts 〉 65 yrs with a moderate intensive chemotherapy regimen (Blood, 96(11): 3104a, 2000) the results in 94 pts were poor with a CR rate of 48% and a survival (OS) 55 yrs (age limit for allo SCT) according to status for 1) Ph/BCR-ABL, 2) CD20 expression and 3) a separate protocol for mature B-ALL. For 1) and 2) chemotherapy was similar to the pilot study (induction I,II consol. I–V with 2xIDMTX/MP,2xVM26/AC and reinduction). Out of a total of 824 pts recruited for the GMALL 06/99 109 were older than 55 yrs. 1) Imatinib in Ph/BCR-ABL+ ALL: In a prospective randomized trial pts received a 4 wk induction with 600 mg/d Imatinib (ImInd) compared to chemotherapy without Imatinib (ChInd). 36 pts (median age 67y) were evaluable (18 ImInd; 18 ChInd). The CR rate was higher for the Imatinib arm with 93% compared to only 44% with chemotherapy (p=.003). 3 of the 4 failure pts in the ChInd arm achieved CR after cross-over to ImInd. There were more non-hematologic severe (grade III/IV) adverse events during ChInd (pneumonia N=6 sepsis 2, enteritis 2, hepatotoxicity 1) versus ImInd (N=0). After induction both arms received the consolidation cycles parallel with Imatinib 600 mg/d for 1 yr. After a median follow-up of 4.3 mo (0.5–20+) 21 pts are in CCR and 6 relapsed. 7 pts died in CR. The OS at 18 mo is 47%. 3 pts (11%) achieved molecular remissions. 2) Rituximab in CD20+ ALL: In the 2nd study pts with CD20+ B-prec. ALL (Ph/BCR-ABL neg) received 375 mg rituximab before each cycle (induction I, II, consolidations). The small group of CD20neg ALL received the similar chemotherapy regimen without rituximab. 26 pts are evaluable (19 with rituximab and 7 with CD20 neg B-prec. or T-ALL). The median age is 66 (55–79) yrs. The CR rate in CD20+ pts is 63% and the OS after 1 yr is 54%. No pts died in CR so far. 3) Rituximab in mature B-ALL, Burkitt or other high-grade NHL: Elderly pts 〉 55 yrs with these diseases had a poor outcome with the former protocol B-NHL90 (Blood100(11):159a, 2002). The CR-rate in 45 pts was 71% and the OS 39% at 6 yrs. Therefore in the subsequent trial B-NHL2002 pts with mature B-ALL/B-NHL 〉55 yrs (86% CD20 pos) received a total of 8 cycles rituximab (375 mg), 6x before each chemotherapy cycle (day −1) and 2x rituximab only. In 26 evaluable pts the CR-rate increased to 81% and the OS at 1.5 yr is 84% (p=.03 compared to study B-NHL90). Out of 21 CR pts 19 are in CCR, 1 relapsed and 1 went off-study. Conclusion: In elderly ALL pts the application of Imatinib in Ph/BCR-ABLpos or rituximab in CD20+ pts led to a stubstantially improved antileukemic activity with high CR and low failure rates. The risk of infections remains a major problem and improved supportive measures are needed. Hopefully this risk stratified approach with targeted therapies will translate into improved long-term outcome in this age category (partly supported by Novartis Pharma and Hoffmann-La-Roche)

Description: Dendritic cells (DC) initiatiate immunity and maintain tolerance. They internalize exogenous antigen and convert it into immunogenic peptides by lysosomal proteolytic degradation, ultimately followed by presentation to CD4 T cells. Monocyte-derived DC (MO-DC) generated in vitro with GM-CSF and IL-4 serve as prototype DC to analyse the cellular biology and biochemistry of DC. However, different types of primary DC, whose functional role in vivo and relationship to MO-DC generated in vitro is unclear, reside in human tissue as well as peripheral blood. The composition of lysosomal proteases in these primary human DC1 and DC2-cells and the way they handle a clinically relevant antigen are unknown, and there is no comparison of the lysosomal processing of antigen by these primary DC to that in primary human B cells or MO-DC generated ex vivo. We have isolated human peripheral blood (PB) DC1 and DC2 cells as well as primary B lymphocytes by magnetic separation and isolated lysosomal compartments from these cells, as well as from MO-DC. Expression and activity of endocytic proteases were assessed by western blot and active site-restricted affinity labelling using a synthetic probe that selectively binds to the active centre of cysteine proteases and allows a simultaneous semiquantitaive assessment and identification of multiple active protease species. In this analysis, PB-DC1 and DC2-cells lacked significant active Cathepsins (Cat) S, L and B as well as asparagine-specific endoprotease AEP, the major enzymes involved in antigen processing in the MHC II-compartment. Surprisingly, lysosomal extracts from PB-DC1 were by far more effective than MO-DC in processing the muliple sclerosis-associated autoantigen myelin basic protein (MBP) in vitro. When analyzed on a molecular scale using mass spectrometry, MBP processing was dominated by CatS, CatD and AEP in MO-DC, as expected, similar to B-lymphoblastoid cells (BLC). PB-DC, however, did not generate proteolytic processing intermediates indicative of CatS or AEP activity but showed the same pattern as primary B-lymphocyte-derived lysosomes, i.e. processing was performed by two cleavage sites that can be reproduced by purified CatG in vitro, suggesting a CatG like dominant lysosomal protease. While active CatG was present in primary human B cells, PB-DC1 cells lacked CatG protein by western blot, suggesting the presence of an as yet unknown dominant endoprotease with CatG-like activity in PB-DC1. By cleaving MBP after pos F90 and F114, this protease directly eliminates the integrity of the major immunodominant MBP epitope MBP85-99. This might lead to poor presentation of this epitope to regulatory T cells resulting in inefficient silencing of MBP-autoreactive T cells during the development of autoimmunity. Our results emphasize the need to apply state-of-the-art biochemical tools to primary human types of APC for the understanding of antigen processing and the rational design of tolerogenic or immunotherapy approaches towards human malignant and autoimmune disorders.

Description: Relapse is the leading cause of treatment failure after allogeneic SCT of Hodgkin Disease (HD). As Ebstein-Barr infection (EBV) is associated with 60% of all HD cases, adoptive immunotherapy with donor derived EBV-specific T-cells lines has resulted in disease control of allogeneic SCT. Potential targets for the adoptively transferred T-cells are the type II latency protein LMP-1 and LMP-2a, which are both homogenously expressed by HD cells. In healthy individuals, both LMP-1 and LMP-2a elicits subdominant CD8+ T-cell responses with frequencies of less than 1:10000. LMP-1 and LMP-2a specific T-cells from 1x108 PBMC derived from HLA A*0201+healthy donors were stimulated with the HLA A*0201 LMP1-epitopes YLLEMLWRL and YLGQNWWTL and the HLA A*0201 LMP-2a epitope CLGGLLTM. Activated T-cells were selected by the cytokine secretion assay and expanded for 10 days. In 85% of donors 1.7 x106 (range 0.7 –4.5 x106; n=13) LMP-1 or LMP-2a specific CD8+ T-cell could be generated with an average purity of 83% as determined by tetramer staining. LMP1- and LMP2a-specific CD8+ T-cells were then expanded 3000 x in 14 d by the rapid expansion protocol and evaluated functionally for cytokine production and specific lysis. Both LMP-1 and LMP-2a specific CD8+ T-cells retained specific cytokine production if stimulated with peptide pulsed targets, efficiently lysed peptid pulsed targets. Surprisingly, if LMP-1 was presented endogenously by EBV positive targets or by targets cells transduced with LMP-1, no cytokine production or specific lysis was detected despite protein expression of LMP-1 in all targets. In contrast, IFN-γ production could be readily detected in LMP-2a-specific CD8+ T-cells after stimulation with target cells processing endogenously the LMP-2a antigen as well as specific lysis of EBV positive target cells. Furthermore, LMP2a specific CD8+ demostrated also specific lyse of Hodgkin-cells expressing the LMP2a (30:1 E/T ratio; 29,3%) where as LMP-1-specific CD8+ T-cells could not lyse HD-cells. In summary, LMP-1 and LMP-2a specific T-cells, although present at undectable levels in healthy donors, can be readily selected and expanded to up to 6x109 antigen-specific T-cells in less than 4 weeks starting from 1x108 PBMC. Based on this data, adoptive immunotherapy of relapsed EBV positive HD after allogeneic SCT should be preferentially performed with LMP-2a specific CD8+ T-cells rather than with LMP-1 specific CD8+ T-cells.

Description: Juvenile myelomonocytic leukemia (JMML) is a rare disease in childhood which can only be cured by stem cell transplantation. The major complication is relapse in up to half of the patients. The existance and efficacy of graft-versus-leukemia (GvL) in JMML is controversial and often associated with severe graft-versus-host disease (GvHD). A 1,5 year old boy developed JMML and was transplanted from a 1 antigen mismatched UD (unmanipulated bone marrow, 8.5 Mio CD34/kg) after a CR consisting of Bu 16*1.25 mg/kg), Cy (2*60 mg/kg), Mel (1*140 mg/m2) and ATG (3*20 mg/kg). GvH prophylaxis consisted of CsA and very short MTX. The situation was further complicated by the intermittent presence of CMV, HHV-6 and EBV in the peripheral blood which was treated intermittently by intravenous ganciclovir. Engraftment occurred on day + 16. GvHD III° of the skin only developed and was treated with corticosteroids, CsA and MMF. Chimerism was complete on day +28. Beginning on day +45 an increasing autologous chimerism was detected. Therefore, immunosuppression was halted. Despite discontinuation of all immunosuppressants the autologous chimerism increased to 60–80% (d +63) and the peripheral leukocytes increased to approx 30,000/μl together with eosinophilia (d +60). Clinical signs of relapse (hepatomegaly and pulmonary obstruction) were also present. Thereafter, within a week, leukopenia and thrombocytopenia developed and the autologous chimerism decreased to 1–5%. Coinciding with the apparent GvL effect severe GvHD reappeared. Skin GvHD II–III° developed, than gut GvDH III° with massive life threatening fluid and potassium loss (day +73). In an attempt to treat both JMML and GvHD the antimetabolite purinethol 50 mg/m2 daily was given orally. Since day + 98 always an complete chimerism was observed. Gut GvHD gradually improved without further immunosuppression. The boy is now at home without evidence of disease or active GvHD more than 1 year after relapse. We speculate that in this case purinethol controlled not only the severe gut GvHD after BMT but also JMML. This antimetabolite may therefore be considered as an immunosuppressant for GvHD when malignat relapse is also present or imminent.

Description: The procoagulant enzymatic complex, prothrombinase, which is required for normal hemostasis, is composed of the enzyme, factor Xa, the protein cofactor, factor Va, associated on a cell surface in the presence of divalent metal ions. Incorporation of factor Va into prothrombinase and its interaction with factor Xa increases the catalytic efficiency of the enzyme by five orders of magnitude as compared to factor Xa alone. While the importance of the contribution of factor Va to the activity of factor Xa for rapid thrombin formation by prothrombinase at the place of vascular injury has been long established, the consequence of the interaction of the cofactor with the members of prothrombinase and the molecular mechanism by which factor Va accelerates prothrombin activation remains an enigma. Prothrombin is activated following two cleavages (Arg271/Arg320). Depending on the order of peptide bond cleavage different intermediates are formed. Factor Xa alone cleaves prothrombin sequentially, first at Arg271 to produce fragment 1•2 and prethrombin-2, followed by cleavage at Arg320 to produce fragment 1•2 and thrombin. The prothrombinase complex catalyzes the activation of prothrombin following the opposite pathway (Arg320 followed by Arg271), resulting in a formation of an active intermediate (meizothrombin) and a 300,000-fold increase in the rate of the overall reaction compared with the rate of prothrombin activation observed with factor Xa alone. We have shown that amino acid region 307–348 of factor Va heavy chain is critical for cofactor activity. A peptide containing this amino acid sequence (42 amino acids, N42R) was found to interact with fluorescently labeled factor Xa and to inhibit prothrombinase activity. Our present data show that N42R can be cross-linked to the heavy chain of membrane-bound factor Xa in the presence of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC). We have also demonstrated that amino acid region 323–331 from N42R (AP4′) contains a binding site for factor Xa of factor Va heavy chain. Our present data show that a peptide containing amino acid residues 317–326 (AP3) inhibited both prothrombinase activity and the high affinity interaction of factor Va with factor Xa on the membrane surface. Moreover, we have found using site directed mutagenesis and recombinant factor Va that amino acids at the NH2-terminal end of AP4′ (i.e. residues 323–325, Glu-Tyr-Phe) are responsible for the inhibitory effect of AP3 and AP4′ and are crucial for the interaction of factor Va with factor Xa. A tripeptide with this sequence inhibited prothrombinase activity in an assay using a fluorescent thrombin inhibitor. To identify the effect of these peptides on factor Xa’s ability to cleave and activate prothrombin, we studied prothrombin activation by gel electrophoresis. The data demonstrated that several peptides that inhibited both the factor Va-factor Xa interaction on the membrane surface and prothrombinase activity, had the ability to accelerate cleavage of prothrombin by factor Xa alone, in the absence of factor Va. Specifically, N42R and AP3 were found to increase the rate of prothrombin consumption by factor Xa by approximately four-fold when compared to factor Xa acting alone. Both peptides induced acceleration in prethrombin-2 formation suggesting an increased in the rate of cleavage of prothrombin at Arg271. These data suggest that the binding of factor Va to factor Xa through amino acid region 323–331 alone produces an effect on factor Xa that increases its potency for cleavage at Arg271.

Description: This phase 2 pilot study was conducted to determine the efficacy and safety of imatinib mesylate in patients with c-kit–positive acute myeloid leukemia (AML) refractory to or not eligible for chemotherapy. Twenty-one patients were enrolled and received imatinib 600 mg orally once daily. Five responses were seen primarily in patients, starting with relatively low blast counts in bone marrow (BM) and peripheral blood (PB): 2 patients who were considered refractory on chemotherapy on the basis of persistence of blasts in PB and BM met the criteria for complete hematologic remission, 1 patient had no evidence of leukemia, and 2 patients achieved a minor response. Treatment with imatinib demonstrated a good safety profile and was well tolerated. Western blot analysis and immunohistochemistry demonstrated c-Kit activation in primary AML cells. Further, imatinib treatment of primary AML cells inhibited c-Kit tyrosine-phosphorylation. Genomic DNA-sequencing of c-KIT showed no mutations in exons 2, 8, 10, 11, 12, and 17. Although some of the responses derived from relatively small reductions in leukemic blasts and may be attributable, in part, to prior chemotherapy, these cases suggest that imatinib has interesting clinical activity in a subset of patients with c-kit–positive AML. Further clinical trials are warranted to explore the clinical potential of imatinib in AML and to identify the underlying molecular mechanism.