ALBERT

Description: Background: The International Prognostic Scoring System (IPSS) for MDS has recently been revised (IPSS-R). However both scoring systems were developed after exclusion of therapy-related cases and data on its usefulness in treatment-related MDS (tMDS) is limited. Aims and Methods: We analyzed 1837 pts from Spanish, German, Swiss, Austrian, US, Italian, and Dutch centers diagnosed 1975-2015. Complete data to calculate the IPSS/-R was available in 1511 pts. The impact of prognostic features was analyzed by uni- and multivariable models and estimated by a measure of concordance for censored data (Dxy). Results: Median age was 68 years. 1% of pts had 5q-syndrome, 13% RCUD, 4% RARS, 27% RCMD/-RS, 18% RAEB 1, 18% RAEB 2, 4% CMML 1, 2% CMML 2, 3% MDS-U, and 7% AML (RAEB-T) according to WHO-classification. Regarding cytogenetics 38% exhibited good, 14% intermediate, and 48% poor-risk according to IPSS, and 2% very good, 36% good, 17% intermediate, 15% poor, and 31% very poor according to IPSS-R. Prognostic risk groups were 12% IPSS low, 34% int 1, 36% int 2, and 18% high, while the IPSS-R was very low in 8%, low in 20%, intermediate in 17%, high in 23%, and very high in 32%. The most frequent primary diseases were NHL 28%, breast cancer 16%, myeloma 6%, prostate cancer 6%, Hodgkins disease 5%, and 4% gastrointestinal tumors. Patients received chemotherapy in 75% and radiotherapy in 47%. Regarding chemotherapeutic drugs, most pts received combination regimens containing alkylating agents in 65%, topoisomerase inhibitors in 44%, antitubulin agents in 26%, and antimetabolites in 26%. Median follow-up from MDS diagnosis was 59 months, median survival 16 months. Since a disease altering treatment is, at least in higher risk disease, which is overrepresented in tMDS, standard of care, we decided to analyze treated as well as untreated pts to avoid a selection bias. This included stem cell transplantation in 16% with a median survival of 24 months. Features with influence on survival and time to AML in univariable analysis included FAB, WHO, IPSS, IPSS-R, cytogenetics, hb, platelets, marrow and peripheral blasts, ferritin, LDH, fibrosis, ß2-microglobulin, and use of alkylating agents for the treatment of primary disease. For hemoglobin, platelets, LDH, fibrosis, and ß2-microglobulin the influence was stronger on survival. Year of diagnosis, age, gender, neutrophil count, WBC, use of chemo or radiotherapy as well as other chemotherapeutic agents had no marked influence on both outcomes. According to our results, both the IPSS (Dxy 0.29 for survival, 0.32 for AML) and IPSS-R (Dxy 0.34, 0.32 for AML) perform moderately in tMDS, but not as well as in primary MDS (pMDS). Therefore, existing prognostic models need to be adjusted to tMDS. However, this appears to be not without difficulties. The scores tested, as well as most prognostic variables themselves perform inferior compared to pMDS. It becomes even more complicated since tMDS in itself is even more heterogeneous than pMDS. Scores and variables perform differently depending on the primary disease or therapy. The IPSS/-R and its variables perform for example better in pts with solid tumors compared to hematologic diseases or in pts who have received radio- instead of chemotherapy, but also in pts after prostate compared to breast cancer. In addition to the integration of further variables, new cutoffs, or the weighting of existing variables, we are currently testing the possibility of separate score versions for different tMDS subgroups. Separate score versions for survival and time to AML would also give differing weights to most features. Hemoglobin, platelets and cytogenetics would get more weight for survival, while marrow blasts would be more important regarding AML. Conclusion: In contrast to early descriptions of tMDS, with poor risk cytogenetics in the vast majority of pts and a uniformly poor prognosis, surprisingly we find good risk karyotypes in a relatively large number of pts. Although, poor risk cytogenetics are still overrepresented, this indicates, different types of tMDS exist. Our analysis shows that many variables exhibit prognostic influence in tMDS and the IPSS or preferably IPSS-R can be applied in these pts. However, the prognostic power of both scores is inferior compared to pMDS, making an optimized tMDS score reasonable. Currently data from further IWG centers is integrated in our database and further analyses are performed to propose a tMDS specific score. Figure 1. Figure 1. Disclosures Komrokji: Novartis: Research Funding, Speakers Bureau; Pharmacylics: Speakers Bureau; Incyte: Consultancy; Celgene: Consultancy, Research Funding. Sekeres:TetraLogic: Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. Steensma:Celgene: Consultancy; Incyte: Consultancy; Amgen: Consultancy; Onconova: Consultancy. Valent:Novartis: Consultancy, Honoraria, Research Funding; Ariad: Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria; Pfizer: Honoraria; Celgene: Honoraria. Platzbecker:Boehringer: Research Funding; Celgene: Honoraria, Research Funding; Novartis: Honoraria, Research Funding. Esteve:Celgene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria.

Description: Recently, we have established a 5-parameter flow cytometry (FCM)-based score allowing for a precise prediction a deletion (5q) in therapy naïve MDS patients. The aim of this prospective study was to test, whether this FCM-based profiling is at least equal to the cytogenetics/FISH-based del(5q) detection for monitoring response to treatment. Overall, 229 FCM investigations were performed in 57 patients with MDS and del(5q) (IPSS-R very low/low: n=24, int: n119, high/very high n=22) including 39 patients with isolated del(5q) or one additional cytogenetic abnormality. The majority of analyses were performed in patients receiving lenalidomide or azacitidine (n=28 and n=21 patients), or in patients receiving chemotherapy and/or allogeneic transplantation (n=3), or growth factors (n=5). The del(5q)-FCM-score includes the following 5 parameters: myeloid progenitors (myPC 〉 2%) = 3 points, CD45 MFI ratio (lymphocytes: myPC ≤ 7.0) = 10, SSC ratio (granulocytes : lymphocytes 〈 6.0) = 2, CD71 (≤ 20%) on granulocytes = 1.5, and female gender = 1.5; a score ≥ 15.0 indicates the presence of del(5q). A standardized FCM (lyse-stain-wash) and cytogenetics/FISH were performed according to ELN guidelines at the TU of Dresden, VUMC of Amsterdam, UH of Bristol, and UH of Guadalajara. Before therapy, in 61 cytogenetic/FISH analyses in 40 MDS patients a del(5q) was detectable. In 53/561 (87%) FCM measurements, performed in parallel, a del(5q) could be predicted using the del(5q)-FCM-score. Monitoring response to treatment, a cytogenetic complete response (CCR) with the disappearance of del(5q) was accompanied by the disappearance of the typical del(5q)-FCM-profile in all of the 50 (19 patients) FCM measurements (sensitivity=100%). Otherwise, in patients without CCR the presence of del(5q) could be predicted by FCM in 96/118 measurements (specificity=81%). Aiming at a still higher specificity, in the following analyses we included only patients who presented with a typical del(5q)-FCM-score before therapy (33 patients; 54 measurements; median score=16.5) resulting in the above described sensitivity of 100% (32 measurements; median score=13.0) as well as a remarkably high specificity of 97% (59/61 measurements; median score=16.5) for response prediction. Next, we compared cytogenetics/FISH and del(5q)-FCM-score with further methods for response monitoring as cytomorphology, two well established diagnostic FCM scores: FCSS (flow cytometry scoring system; Wells et al. 2003) and the diagnostic score (Ogata et al. 2009), as well as the assessment of hematological improvement (HI). Thus, cytomorphology and FCSS, analyzing dyspoiesis of multiple cell lineages, showed a CR or disappearance of a MDS typical FCSS in less than the half of all investigations being in cytogenetic CR (sensitivity: 41% and 38%), but those two methods revealed a high specificity (98% and 97%). On the other side, the analysis of HI was high sensitive (91%) but not specific (49%). The use of the diagnostic Ogata score, considering almost only abnormalities of the myeloid progenitors, ended up with a slightly lower sensitivity (91%) and specificity (89%) as cytogenetics/FISH and the del(5q)-FCM-score. Finally, response monitoring using the del(5q) FCM-score allowed for a better separation of overall survival compared to cytogenetics/FISH (p=0.039 vs. p=0.1725). Flow cytometry-based detection of a del(5q)-specific immunophenotype is feasible and can serve as a rapid tool for response monitoring during treatment with disease-modifying drugs. At the moment, we test whether the better separation of the patients' survival curves applying the FCM-score holds true in a larger patient cohort to be analyzed within the ELNet iMDS-Flow working group. Disclosures Platzbecker: TEVA: Honoraria, Research Funding.

Description: Abstract 964 Background: High dose immunosuppressive therapy and hematopoietic stem cell transplantation (HSCT) has shown efficacy in severe or rapidly progressive systemic sclerosis (SSc) in phase 1 and 2 trials with durable responses in two thirds of patients (pts), while a recent phase 2 randomised trial in 19 SSc pts showed superior benefit of HSCT over iv pulse cyclophosphamide (Cy) on skin score and lung function. Methods: The ASTIS-trial (Autologous Stem cell Transplantation International Scleroderma trial) is a multinational prospective randomized controlled phase 3 trial, comparing safety and efficacy of HSCT versus Cy in early progressive dcSSc pts with disease duration of a) 4 years or less and evidence of organ involvement or b) of 2 years or less and evidence of systemic inflammation with or without major organ involvement. Major exclusion criteria were: concomitant severe SSc disease (mean PAP 〉 50 mmHg, DLCO 〈 40% predicted, creatinine clearance (CCl) 3months oral) treatment), liver failure. Pts randomized to the transplant arm underwent mobilization with Cy 2×2 g/m2 + G-CSF 10mcg/kg/d, conditioning with Cy 200 mg/kg, rbATG 7.5 mg/kg, followed by reinfusion of CD34+ autologous HSCT. Controls were treated with 12× monthly iv pulse Cy 750 mg/m2. Crossing over was allowed after 2 years. The primary endpoint was event-free survival (EFS), defined as survival until death or development of major organ failure at 2 yrs. Toxicity according to WHO criteria and progression free survival (defined as worsening of modified Rodnan skin score, functional ability, major organ function) were the main secondary endpoints. The effects of treatment were analyzed on an ITT basis and by comparing EFS using the KM survival curves (using log-rank test) and Cox models. Results: 156 pts (female 59%), from 27 centers were enrolled in 10 countries from March 2001 until October 2009 and randomized to HSCT (n=79) or iv pulse Cy (n=77). Seventy-five pts in each arm started treatment, 70 pts in HSCT and 58 pts in control groups completed treatment. The median time (Interquartile Range (IR)) from randomization to completion of treatment was 93 (43.0) days in the HSCT and 338 (41.75) days in the control groups respectively. Baseline characteristics (mean (SD)) of the pts were: age 44 (11.2) yrs, SSc duration 1.4 (1.3) yrs, BMI 24 (14.4), Rodnan skin score 25 (8), HAQ 1.35 (0.8), prior Cy therapy 22%, creat cl 116 (39.5) ml/min, LVEF 65% (8.5), DLCO 59% (14), with no significant differences between the 2 arms. With data cut at 1 May 2012, median follow-up (IR) are 33 (42.0) and 27 (34.0) months in the HSCT and control groups respectively. Forty two events occurred : 18 in the HSCT group (16 deaths and 2 irreversible renal failures) and 24 in the control group (24 deaths). Event-free survival was time-dependent with a hazard ratio at 84 months of 0.22 (95% CI 0.08–0.58, P= 0.002). Eight deaths (including 1 during mobilization and 1 after conditioning) in the HSCT group were deemed treatment-related by the independent data monitoring committee with heart failure (3), ARDS (2), multiple organ failure (2) and pulmonary oedema (1) as the causes of death. In the control group, none died from treatment causes and most deaths were due to progressive disease. Eight pts in the control arm received rescue HSCT treatment, one of whom later died from secondary acute myeloid leukaemia. Two HSCT pts received rescue iv Cy therapy. Conclusions: The ASTIS-trial is the first international, investigator-initiated, phase 3 HSCT trial in early diffuse cutaneous systemic sclerosis. The data show that despite 10% treatment-related mortality, long term event-free survival and overall survival were better in the HSCT group than in the group treated with iv pulse cyclophosphamide. (Funded by the European Group for Blood and Marrow Transplantation, European League Against Rheumatism, AP-HP, NIHR, DIGR, Imtix-Sangstat, Miltenyi-Biotec, Amgen Europe; Current Controlled Trials number, ISRCTN 54371254). Disclosures: No relevant conflicts of interest to declare.

Description: The immune system plays a role in the pathogenesis of myelodysplastic syndrome (MDS) but its precise contribution to disease development and control is not fully clarified. T cell activation could reflect undesired autoimmune reactions against normal hematopoietic precursor cells as well as effective immune-surveillance against dysplastic clones. We have investigated lymphocyte subsets and activation markers of 42 low risk and intermediate-1 risk MDS patients and compared them to those of intermediate-2 risk, high risk MDS patients, and healthy donors. In low and intermediate-1 risk MDS patients, we have found an activated state of lymphocytes, determined by increased percentages of effector T cells with cytotoxic profile, increased number of clonal expansions, increased frequencies of Wilms’ Tumor 1 (WT1) specific lymphocytes and decreased regulatory T cell activation, as compared to healthy donors. Moreover, we demonstrate autologous T cell mediated cytotoxicity against aberrant hematopoietic precursor cells. These findings provide evidence for the existence of immune-surveillance in the pathogenesis of low and intermediate-1 risk MDS patients. Our data are important for adequate evaluation of the role of immune-modulatory drugs in the future and justify the reconsideration of the role of immune-suppressing therapy for low and intermediate-1 risk MDS patients.

Description: To develop a prognostic scoring system tailored for therapy-related myelodysplastic syndromes (tMDS), we put together a database containing 1933 patients (pts) with tMDS from Spanish, German, Swiss, Austrian, US, Italian, and Dutch centers diagnosed between 1975-2015. Complete data to calculate the IPSS and IPSS-R were available in 1603 pts. Examining different scoring systems, we found that IPSS and IPSS-R do not risk stratify tMDS as well as they do primary MDS (pMDS), thereby supporting the need for a tMDS-specific score (Kuendgen et al., ASH 2015). The current analysis focuses on cytogenetic information as a potential component of a refined tMDS score, based on this large, unique patient cohort. Of the 1933 pts, 477 had normal karyotype (KT), 197 had missing cytogenetics, while 467 had a karyotype not readily interpretable. Incomplete karyotype descriptions will be reedited for the final evaluation. Of the remaining 1269 pts the most frequent cytogenetic abnormalities (abn) were: -7, del(5q), +mar, +8, del(7q), -5, del(20q), -17, -18, -Y, del(12p), -20, and +1 with 〉30 cases each. Frequencies are shown in Table 1. Some abn were observed mostly or solely within complex KTs, such as monosomies, except -7. Others, like del(20q) or -Y, are mainly seen as single or double abn, while del(5q), -7, or del(7q) are seen in complex as well as non-complex KTs. The cytogenetic profile overlapped with that of pMDS (most frequent abn: del(5q), -7/del(7q), +8, -18/del(18q), del(20q), -5, -Y, -17/del(17p), +21, and inv(3)/t(3q) (Schanz et al, JCO 2011)), with notable differences including overrepresentation of complete monosomies, a higher frequency of -7 or t(11q23), and a more frequent occurrence of cytogenetic subtypes in complex KTs, which was especially evident in del(5q) occurring as a single abn in 16%, compared to 70% within a complex KT. IPSS-R cytogenetic groups were distributed as follows: Very Good (2%), Good (35%), Int (17%), Poor (15%), Very Poor (32%). Regarding the number of abn (including incomplete KT descriptions) roughly 30% had a normal KT, 20% 1, 10% 2, and 40% ≥3 abn, compared to pMDS: 55% normal KT, 29% 1, 10% 2, and 6% ≥3 abn. To be evaluable for prognostic information, abn should occur in a minimum of 10 pts. As a single aberration this was the case for -7, +8, del(5q), del(20q), del(7q), -Y, and t(11;varia) (q23;varia). Of particular interest, there was no apparent prognostic difference between -7 and del(7q); del(5q) as a single abn was associated with a relatively good survival, while the prognosis was poor with the first additional abn; t(11q23) occurred primarily as a single abn and was associated with an extremely poor prognosis, and prognosis of pts with ≥4 abn was dismal independent of composition (Table 1). To develop a more biologically meaningful scoring system containing homogeneous and prognostically stable groups, we will further combine subgroups with different abn leading to the same cytogenetic consequences. For example, deletions, unbalanced translocations, derivative chromosomes, dicentric chromosomes of 17p, and possibly -17 all lead to a loss of genetic material at the short arm of this respective chromosome affecting TP53. Further information might be derived from analyses of the minimal common deleted regions. For some abn, like del(11q), del(3p), and del(9q), this can be refined to one chromosome band only (table 1). Conclusion: Development of a robust scoring system for all subtypes of tMDS is challenging using existing variables. This focused analysis on the cytogenetic score component shows that favorable KTs are evident in a substantial proportion of pts, in contrast to historic data describing unfavorable cytogenetics in the majority of pts. Although complex and monosomal KTs are overrepresented, this suggests the existence of distinct tMDS-subtypes, although some of these cases might not be truly therapy-induced despite a history of cytotoxic treatment. The next steps will be to analyze the prognosis of the different groups, develop a tMDS cytogenetic score, and examine minimal deleted regions to identify candidate genes for development of tMDS, as well as to describe the possible influence of different primary diseases and treatments (radio- vs chemotherapy, different drugs) on induction of cytogenetic subtypes. Our detailed analysis of tMDS cytogenetics should reveal important prognostic information and is likely to help understand mechanisms of MDS development. Disclosures Komrokji: Novartis: Consultancy, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Sole:Celgene: Membership on an entity's Board of Directors or advisory committees. Sekeres:Celgene: Membership on an entity's Board of Directors or advisory committees; Millenium/Takeda: Membership on an entity's Board of Directors or advisory committees. Roboz:Cellectis: Research Funding; Agios, Amgen, Amphivena, Astex, AstraZeneca, Boehringer Ingelheim, Celator, Celgene, Genoptix, Janssen, Juno, MEI Pharma, MedImmune, Novartis, Onconova, Pfizer, Roche/Genentech, Sunesis, Teva: Consultancy. Steensma:Amgen: Consultancy; Genoptix: Consultancy; Janssen: Consultancy; Celgene: Consultancy; Millenium/Takeda: Consultancy; Ariad: Equity Ownership. Schlenk:Pfizer: Honoraria, Research Funding; Amgen: Research Funding. Valent:Amgen: Honoraria; Deciphera Pharmaceuticals: Research Funding; Celgene: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Ariad: Honoraria, Research Funding; Deciphera Pharmaceuticals: Research Funding. Giagounidis:Celgene Corporation: Consultancy. Giagounidis:Celgene Corporation: Consultancy. Platzbecker:Celgene Corporation: Honoraria, Research Funding; TEVA Pharmaceutical Industries: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Janssen-Cilag: Honoraria, Research Funding; Amgen: Honoraria, Research Funding. Lübbert:Janssen-Cilag: Other: Travel Funding, Research Funding; Celgene: Other: Travel Funding; Ratiopharm: Other: Study drug valproic acid.

Description: It is generally accepted that myelodysplastic syndromes (MDS) most often originate in a multipotent, myelorestricted progenitor population, although primary transformation may occur at the hematopoietic stem cell level. MDS can be classified into low risk and high risk with evolution to acute myeloid leukemia (AML) predominantly in the latter cases. In AML, survival of leukemia-initiating cells, often referred to as leukemic stem cells, after chemotherapy is thought to lead to minimal residual disease and relapse. Hence, in de novo AML a larger size of the stem cell compartment is predictive for poor survival. [Van Rhenen et al.,Clin Cancer Res 2005,11] The monoclonal antibody against the cell surface antigen C-type lectin-like molecule-1, CLL-1, together with lineage infidelity markers enables discrimination of normal and malignant stem cells. [Van Rhenen et al.,Blood 2007,110; Van Rhenen et al.,Leukemia 2007,21] It could be hypothesized that CLL-1 and aberrant marker expression on MDS stem cells together with size of the stem cell compartment may predict leukemic evolution. Therefore, stem cells, defined as CD45dimCD34+CD38−, were analyzed for expression of CLL-1 and aberrant lineage markers in bone marrow samples from 88 MDS patients classified by WHO as 16 RA w/o RS, 42 RCMD w/o RS, 3 MDS-U, 5 hypoplastic MDS, 6 MDS/MPD and CMML, 15 RAEB-1 and 2, 20 AML patients with a known MDS history and 26 healthy controls. Analysis of the CD34+CD38− frequency in all MDS patients and normal controls revealed no significant differences (median 0.0061% vs. 0.0074%, respectively), whereas the frequency of CD34+CD38− cells was 17-fold higher in high risk MDS (RAEB-1 and 2, median: 0.076%) as compared to low risk MDS (median: 0.0046%, p20) could be tested in 11/15 high risk RAEB-1 and 2 cases and in 16/73 of the remaining low risk MDS cases. In these cases, median CLL-1 expression on the CD34+CD38− cells was 1.6% (range 0–50) in low risk and 2.0% (range 0–27) in high risk MDS. Median CLL-1 expression on stem cells was 0.0% (range 0–4.7) in normal controls. Nevertheless, expression of lineage infidelity markers, such as CD5, CD7 and CD56, on CD34+CD38− stem cells in MDS strongly suggests that a considerable part of these stem cells is malignant (median 35% in 7/16 patients tested). Our data show that CLL-1 is virtually absent on stem cells in MDS. Remarkably, median CLL-1 expression on stem cells in AML cases that evolved from MDS (7%, range 0–53, n=9) was manifold lower than in de novo AML (median 45% when excluding non de novo AML [Van Rhenen et al.,Blood 2007,110], p=0.034). Detailed analysis of CLL-1 expression in AML had already revealed that CLL-1 expression increases with differentiation (CD34− 〉 CD34+CD38− 〉 CD34+CD38+). [Bakker et al.,Cancer Res 2004,64;Van Rhenen et al.,Blood 2007,110] Thus, our data suggest that the CD34+CD38− cells in high risk MDS and AML with antecedent MDS are more immature than in most de novo AML, which might explain poor prognosis of AML cases with MDS history. To conclude, our data indicate that CLL-1 is a specific marker of de novo AML, while CLL-1-negative AML may have been evolved from a MDS pre-phase that is further characterized by an increasing size of the stem cell compartment upon progression towards AML.

Description: Purpose: This randomized phase II study (HOVON89) in patients with low/int-1 risk MDS refractory or unlikely to respond to erythropoietin and granulocyte-colony stimulating factor (EPO/G-CSF) assessed efficacy and safety of lenalidomide without (Arm A) or with EPO+/-G-CSF (Arm B) in case of no erythroid response after 4 cycles. Patients and methods: In total 200 patients were randomly 1:1 assigned to either Arm A or Arm B. All patients were treated with lenalidomide (10 mg/day/day 1-21) for a minimum of 6 months in arm A and 12 months in arm B or until loss of response or disease progression. Patients in arm B without hematological improvement-erythroid (HI-E) after 4 cycles received EPO (30,000 IU/wk). In those patients who did not show HI-E after 6 months, EPO was increased to 60,000 IE/wk. G-CSF (3x 300-480 µg/wk) was added if no HI-E was reached at 8 month. The current pre-final evaluation was based on the first180 patients and included 85% non-del5q MDS and15% patients with isolated del5q. The median age was 71years (range 38-89). No differences were observed between both arms regarding sex (55% male), WHO PS, WHO diagnostic subgroup and IPSS, baseline Hb, WBC, platelets, endogenous erythropoietin level, pretreatment with EPO+/-G-CSF (67% of the patients were pretreated) and pre-study transfusions. Patients had received a median of 13 (range 0-72) units of RBC and 4 (range 0-13) within 8 weeks for prior study entry. Results: Adverse events were consistent with the known safety profile of lenalidomide/EPO/G-CSF. HI-E according to IWG criteria was achieved in 38% and 41% of the patients for arm A and B, respectively (p = 0.46). HI-E was significantly lower in non-del5q versus del5q patients (33% vs 78%, respectively). Time-to-HI-E was 3.1 months (median; range 1.6-12.3) for both arms with a median duration of 10 months (range 1 - 76). The median PFS was 14.4 vs 15.4 months in arms A and B (p=0.43). OS was 51.1 and 37.7 months for arm A and B (p=0.09). At 2 years 17% of patients had progressed to AML (no differences between arms). The median FU of patients still alive is 31 months. PFS and OS was significantly longer in those who achieved HI-E, (median 13 vs 19 months, p=0.02 for PFS and median 31 vs 63 months for OS, p

Description: Myelodysplastic syndromes (MDS) are a group of clonal disorders of the bone marrow characterized by peripheral cytopenias. Standard treatment in low- and intermediate-I–risk MDS is supportive therapy consisting of regular transfusions and growth factors, that is, erythropoietin (Epo) and granulocyte-colony-stimulating factor (G-CSF). Because flow cytometric analysis of MDS bone marrow samples can identify clinically relevant subgroups regarding transfusion dependency and disease progression, we addressed the question whether flow cytometry (FCM) was instrumental in predicting response. In 46 patients with low- and intermediate-I–risk MDS that were treated with Epo/G-CSF, low Epo level and low transfusion need were associated with response to Epo/G-CSF. Interestingly, aberrant phenotype of myeloblasts identified nonresponders among patients with the greatest response probability according to the predictive model of Hellström-Lindberg et al. Moreover, aberrant FCM of myeloblasts acted as a significant biomarker for treatment failure in multivariate analysis. A new predictive model based on the basis FCM combined with previously validated Epo levels is proposed defining 3 subgroups with 94%, 17%, and 11% response probability. In conclusion, FCM may add significantly to well-known predictive parameters in selecting MDS patients eligible for Epo/G-CSF treatment. This is of relevance regarding prevention of treatment failure.

Description: MHC class II molecules are able to present tumor antigens to CD4+ T cells which play in their turn an important role in orchestrating the anti-tumor immune response. MHC class II molecules are only able to present antigen when the antigen binding site has been liberated from CLIP, which is a remnant of the intracellular chaperone molecule called Invariant Chain. Impaired MHC class II antigen presentation by persistent expression of CLIP on the antigen binding site of 〉 35% of the leukemic myeloid cells at diagnosis of AML patients is correlated to shorter overall survival (Chamuleau et al, Cancer Res.2004; 64:5546–5550). In this study, we investigated the CLIP expression on minimal residual disease (MRD) cells in the bone marrow of patients who achieved complete remission after chemotherapeutic treatment. Such expression may reveal the role of immune control in the outgrowth of MRD cells towards a relapse. The presence of MRD was measured by leukemia associated phenotype (LAP) expression (e.g. expression of the lymphoid cell marker CD7 or natural killer cell marker CD56 on myeloid blasts). Such aberrancies can be defined on AML blasts at diagnosis. At first, we established the percentage of MRD cells of 19 patients who remained in continuous complete remission (median follow up 44 months, range 7.4–109 months, sample taken at median 21 months after complete remission) and of 15 patients who relapsed soon after samples were taken (median time before relapse occurred: 5.9 months, range 1.4–20 months). The median frequency of MRD cells in relapsing patients was 0.1% (range 0.01 – 3.1%) compared to 0.02% (range 0.01–0.09%) in patients who remained in continuous remission. Differences were significant (p=0.017, Mann-Whitney U), in line with our previous finding that a high MRD cell frequency correlates with a high relapse rate (N. Feller et al, Leukemia2004, 18:1380–1390). Furthermore, we established the CLIP expression on the CD34+ LAP+ cells of both groups. Patients that relapsed showed a significant higher median CLIP expression (69%, range 6–96%, SD 27) than the patients that remained in continuous complete remission (median CLIP expression of 31.6% (range 5–93%, SD 26)) p=0.012 (Mann-Whitney U). In a logistic regression analysis both parameters were independent factors for predicting relapse (p=0.014 for CLIP expression and p=0.035 for MRD frequency). In conclusion, the impaired immunogenicity of low frequency MRD cells in patients that are morphologically in complete remission seems to play an important role in the outgrowth of MRD to relapsing leukemia. Enhancing the immunogenicity of MRD cells by restoration of the MHC class II antigen presentation pathway could offer new possibilities for immune therapy of AML patients.