ALBERT

Description: Introduction: 30% of Hodgkin Lymphoma (HL) patients are refractory or relapse (RR) after first line therapy. Salvage chemotherapy followed by high-dose chemotherapy and with Autologous Peripheral Blood Stem Cell Transplantation (APBSCT) can cure many patients, but those who are transplanted with active disease detectable by PET-CT have a very poor prognosis. Therefore, the current challenge in HL is to improve the results of the pre-transplant chemotherapy. We and others have demonstrated that the addition of Brentuximab Vedotin (BV) to chemotherapy can produce very good results. Objectives: We conducted a phase II trial to assess response rate with combined Brentuximab vedotin and ESHAP chemotherapy [BRESHAP] as 2nd line therapy for RRHL prior to APBSCT (ClinicalTrials.gov #NCT02243436). Methods: Primary efficacy endpoint was the proportion of complete responses (CR) pre-APBSCT. A prior phase I step was carried out to establish the appropriate dosis. Final treatment consisted of Brentuximab Vedotin (1.8 mg/m2/day IV, D1), Etoposide (40 mg/m2/day IV, D1-4), Solumedrol (250 mg/day IV, D1-4), High dose AraC (2 g/m2 IV, D5) and cisPlatin (25 mg/m2/day IV, D1-4). Results: Patients with relapsed or refractory classical HL (cHL) after one prior line of therapy were eligible. 66 patients were included in the trial. There were 35 females and 31 males, with a median age of 36 years (18-66). At inclusion, 40 patients were considered primary refractory, 16 as early relapses (complete remission -CR- shorter than 1 year) and 10 as late relapses. Currently, all patients have completed the pre-transplant therapy. During that period, there were 22 Severe Adverse Events (SAEs) reported in 15 patients: Fever in 13 occasions (neutropenic in seven, and non-neutropenic in six), hypomagnesemia and gastrointestinal alterations (n=2) and pneumothorax, skin lesions, left ventricular function reduction and pulmonary embolism [PE](n=1). There were 2 deaths: non-neutropenic abdominal sepsis and PE. Grade 3-4 hematologic toxicity presented in 22 cases: neutropenia (n=18), thrombocytopenia (n=12), and anemia (n=5). Grade 3-4 extrahematologic adverse events present in ≥5% of cases were non-neutropenic fever (n=8) and hypomagnesemia (n=3). All patients except three underwent stem cell mobilization after the 1st (n=15), 2nd (n=36) or 3rd (n=12) cycle using subcutaneous G-CSF 5 mcg/Kg/12 h. for 5 days. All patients collected 〉2·10e6/Kg peripheral blood CD34+ cells in all cases (median 5.75, range 2.12-33.4). The number of harvesting procedures was one in 47 patients, two in 13, three in 2 and four in 1. The transplant has been done in 61 patients, with data are available from 47: all engrafted with a median of 9&10 days for neutrophil and platelet recovery, respectively. No major events were registered during transplant period, except for one patient who died at day +110 due to pneumonia. Overall pre-transplant response was 96%, including a 70% and 26% complete and partial remission rates, respectively. Of these forty-seven patients, 37 (80%) were in metabolic CR after transplant and 3 (7%) in PR; six patients were considered as non-responders (13%) and went out of the trial. At a mean follow-up of 11 months, 7 patients have progressed, rendering a projected progression free survival of 87% at one year. Six patients have already died: three due to progression, and the three already mentioned above (PE, abdominal sepsis and pneumonia). With a mean follow-up of 11 months, the projected overall survival was 90% at one year (cause specific, 96%). Conclusions: BRESHAP is a highly effective regimen for remission induction prior to transplant in patients with refractory or relapsed Hodgkin lymphoma. The addition of BV to the conventional chemotherapy did not resulted in a higher toxicity for the pre- and post-transplant periods and it did not hamper the collection of PBSC. Disclosures No relevant conflicts of interest to declare.

Description: Background:The isolation of cell-free DNA (cfDNA) evolved the concept of liquid biopsy. Several works have analyzed the presence of cfDNA in lymphomas, especially in diffuse large B-cell lymphoma (DLBCL) and Hodgkin lymphoma (HL), however there is limited information regarding the detection of cfDNA in other types of lymphomas or the role of cfDNA detection to monitor disease outcome. Objectives:1.- To analyze the presence of cfDNA at diagnosis of patients with lymphoproliferative malignancies. 2.- To evaluate the change in concentration of cfDNA ([cfDNA]) after treatment in DLBCL patients. Material and Methods:A retrospective study in a single center was performed including 221 adult patients since January 2015 to February 2019 with: DLBCL, HL, marginal zone lymphoma (MZL), follicular lymphoma (FL), chronic lymphocytic leukemia (CLL), mantle cell lymphoma (MCL), lymphoplasmacytic lymphoma (LPL) and peripheral T-cell lymphomas (TCL). All patients had plasma samples collected at diagnosis that were stored in the institutional biobank (MarBiobank). The cfDNA were obtained from 1 mL of -80°C frozen stored plasma using the MagMax Cell Free DNA isolation kit (Thermo Fisher Scientific). The cfDNA quantification was performed using the Qubit system with the dsDNA high sensitivitykit (Thermo Fisher) and is expressed as ng/mL of plasma. In addition, patients with DLBCL who were treated with rituximab-CHOP/CHOP-like regimens were evaluated for [cfDNA] analysis, pre and post-treatment, and results were compared with PET-CT scan findings. Results: Stored plasma samples at diagnosis were available in 221 patients: DLBCL 82, HL 22, CLL/LPL 13, FL 36, MZL 37, MCL: 11, TCL 10 and others 10 (B-cell lymphoma unclassified, hairy cell leukemia, Burkitt lymphoma). Successful identification of cfDNA was obtained in 95.9% (212/221) of samples. DLBCL patients showed higher [cfDNA] globally and, DLBCL, HL and FL patients showed a higher concentration than MZL who exhibited the lower concentration of all groups (p=0.009; p=0.013 and p=0.002); see table 1. 50 DLBCL patients with a median follow-up since diagnosis of 25.5 (5-51) months were analyzed. Median age was 67 (19-79) years, males 56% (28). IPI distribution: low-risk 28% (14), low-intermediate 26% (13), high-intermediate 24% (12) and high risk 22% (11) cases. Detection of cfDNA was successful in 100% at diagnosis and in 98% (49) cases post-therapy. The mean [cfDNA] at diagnosis was 2.21 (standard deviation- SD: 1.60) ng/mL with a correlation with LDH concentration (p

Description: DAC is a potent hypomethylating agent with clinical activity in patients with myelodysplastic syndromes (MDS) and acute myelogenous leukemia (AML). VPA is a histone deacetylase inhibitor used as an antiepileptic agent. In vitro, the combination of DAC with VPA results in synergistic antileukemia activity at doses of VPA above 1mM. Based on this data, we have developed a phase I/II study of this combination for pts with leukemia. The phase I of the study followed a classic 3+3 design. The dose of DAC was fixed: 15 mg/m2 iv daily for 10 days. This was based on a previous phase I study (Blood2004;103:1635) that indicated that this schedule had an optimal toxicity-response profile in this population. Three dose levels of VPA were selected: 20, 35 and 50 mg/kg. VPA was given orally for 10 days concomitantly with DAC. 22 pts have completed the phase I portion of the study (median age 56 years, range 4–78, 20 pts AML, 2 MDS). At dose level 1 (20 mg/kg of VPA) no grade III-IV toxicity was observed. At dose level 2 (VPA 35 mg/kg), 2 out 6 pts developed grade III neurotoxicity. Both pts were receiving high doses of other neurotropic agents. After IRB approval, 3 mores pts were treated at this dose level with no significant toxicity. Subsequently, 3 pts were treated at the highest planned dose level (50 mg/kg) with no toxicity observed. This cohort was then expanded to a total of 10 pts. One pt developed grade III neurotoxicity. No other severe drug-related toxicities were observed, but 5 patients at all dose levels developed grade II sedation/somnolence. Pancytopenia was induced in all pts. At dose level 1, one pt with refractory AML achieved complete remission (CR) after the second course of therapy. This is now maintained for 5 courses. At dose level 2, a patient with HIV disease and relapsed AML achieved CR after the third course of therapy, and 2 pts with relapsed AML achieved complete marrow responses (marrow blasts less then 5%, no recovery of peripheral counts). Of 3 pts evaluable for response at dose level 3, 1 pt with MDS has achieved CR after 1 course, and 1 with relapsed AML a complete marrow response. Median free VPA levels pretreatment were 0, and 25 mg/L on both days 5 and 10 and returned to 0 prior to next course. Histone acetylation measured by Western blot was observed in 3 pts (25%), all at doses above 20 mg/kg of VPA. Reactivation of p21 expression was induced in 4 out 11 pts analyzed. Global hypomethylation measured using a bisulfite PCR LINE assay was induced in 1 out 3 pts so far studied. Based on the toxicity observed, the phase II portion of the study was initiated. This is restricted to pts with AML/MDS. Seven pts have been accrued to this phase, and 8 out the 10 pts at dose level 3 of the phase I are also evaluable. The response data of this pts will be updated at the meeting. In summary, the combination of low dose DAC and VPA up to doses of 50 mg/kg can be safely administered to pts with leukemia although it may be complicated by neurotoxicity. Clinical and biological activity was observed at all dose levels.

Description: Introduction: Micro-RNAs (miRNAs) are 19-24 nucleotide non-coding RNAs that regulate gene expression through the inactivation of their messenger RNA. Previous studies have demonstrated the important role of some miRNAs in the development of cancer. Specifically, in diffuse large B cell lymphoma (DLBCL), miRNAs involved in lymphomagenesis were identified but understanding their biological function continues to be a challenge. Nevertheless, the pathogenesis effects of some miRNAs such as miR-125a, miR-17-92 cluster or mi-R-155 are well characterized. Some studies suggest that miRNAs also possess a prognostic potential role in DLBCL. For this reason, our objective was to analyze the different miRNAs involved in the chemo-sensitivity or resistance to the first line treatment, their correlation with standard prognostic factors at diagnosis and the role of these miRNAs in survival in patients with DLBCL. Material and methods: Patients homogeneously treated with R-CHOP from 1999-2013 were reviewed from 3 Spanish centers. They were retrospectively obtained from Pathology Department registry to avoid selection bias. We included those patients with valid genomic material in formalin-fixed-paraffin-embedded tissue and with available clinical data. Samples were processed using the miRNA 4 Affymetrix microarrays kit in a discovery group that included 2 cohorts (patients with durable complete remission (CR) versus refractory or early relapsing patients). Those miRNAs with differential expression were validated in the whole series with quantitative RT-PCR. We also analyzed the role of these miRNAs as predictors of event-free survival (EFS) and overall survival (OS) and their relationship with standard prognostic factors in DLBCL. Results: We identified 156 patients homogeneously treated with R-CHOP. Finally, 96 samples were obtained with valid material for RNA extraction. To identify those miRNAs with prognostic implication, a discovery cohort of 12 patients was used in which all the cases had poor prognosis with high tumor load and advance disease (III-IV stage and unfavorable R-IPI). On this basis of poor prognosis, 2 groups were defined totally opposed from the point of view of the treatment response and evolution: chemo-resistance group (n=6) including refractory or relapsed (RR) patients (first 12 months) and chemo-sensitive group (n=6) including patients with at least 3 years of CR. A hierarchical clustering was performed in which 26 miRNAs differentially expressed were identified. A screening of miRNAs was carried out based on the fold-change and pathways involved and finally we obtained 10 miRNAs differentially expressed in RR group. The validation of these miRNAs was performed with quantitative RT-PCR in the whole series which finally included 68 samples with valid material. A univariate survival analysis including clinical prognostic factors and the selected 10 miRNAs was performed. We confirmed that 7 of them (miR-20b-5p, miR-1244, miR-6840-3p, miR-1231, miR-193b-5p, miR-6860-5p y miR-199a-5p) significantly influenced EFS and 6 of them (miR-1244, miR-1231, miR-193b-5p, miR-885-3p, miR-182-5p y miR-199a-5p) on OS. From these 10 miRNAs, only 3 had a significant prognosis role not only for EFS but also for OS and progression-free survival (PFS): miR-1244, miR-193b-5p and miR-1231. The overexpression of miR-1244 and miR-193-5p were associated with advance stage and worse clinical prognosis factors (p15% were independently associated with worse SG and EFS (Figure 1). In previously reported studies, these 3 miRNAs have been related with proliferative events such as the overexpression of myc or anti-apoptosis. Also, the miR-1231 may be related with new lymphomagenesis pathways associated to viral infections. Conclusions: Through a discovery group focused on progression/refractoriness, a group of new miRNAs differentially expressed on chemo-resistant patients with DLBCL was identified. The overexpression of miR-1244 and miR-193-5p was associated with more extensive disease and worse clinical prognostic factors. The high R-IPI, reduction of 〉15% RDI and the overexpression of miR-1231 were independently associated with worse EFS and OS. Disclosures Sánchez-González: Amgen: Consultancy, Speakers Bureau; Gilead: Speakers Bureau; Navartis: Consultancy, Speakers Bureau; Shire: Speakers Bureau; Takeda: Consultancy, Speakers Bureau. Salar:Roche: Research Funding, Speakers Bureau; Janssen Pharmaceuticals: Consultancy, Speakers Bureau; Gilead: Consultancy, Speakers Bureau; Celgene: Consultancy.

Description: Background: The trombopoietin receptor agonists (TRAs) romiplostim and eltrombopag are effective and safe in the treatment of chronic immune thrombocytopenia (ITP). However, when no response is achieved or when adverse events occur with one TRA the value of the sequential use of romiplostim and eltrombopag has not been clearly established. Here we have evaluated the efficacy and tolerance of using eltrombopag after romiplostim in ITP. Methods: Fifty-one primary ITP patients (aged 18 years or more) who had been sequentially treated first with romiplostim and then with eltrombopag in the Spanish Eltrombopag Registry were retrospectively evaluated. In accordance with the usual standards, complete response was defined as a platelet count of 100x109/L and a response as a platelet count of 30x109/L or a count of at least twice the initial (pre-treatment) value. This study was performed in accordance with the standards of the Helsinki declaration and approved by the Hospital Universitario de Burgos Ethics Committee. Results: The median age of our cohort was 49 [range, 18–83] years. There were 32 women and 19 men. According to the standard definition, patients were allocated to newly diagnosed (n=2), persistent (n=5) and chronic (n=44) ITP groups. The median number of therapies prior to administration of eltrombopag was 4 [range, 2–9], including splenectomy (39%), rituximab (33%) and romiplostim (100%). The median duration of romiplostim use before switching to eltrombopag was 12 (IQR 5–21) months. The reasons for switching from the romiplostim to eltrombopag were: lack of efficacy of romiplostim (n=25), patient's preference (n=16), platelet-count fluctuation (n=6), and side-effects (n=4). The initial response rate to eltrombopag was 41/51 (80.5%), including 67% (n=34) of cases with complete remission. After a median follow-up of 13 months with eltrombopag, 39 patients maintained their response. When eltrombopag was used for patients who were refractory to the maximum romiplostim dose the initial response rate of eltrombopag was 25%. However, 83% of patients who relapsed after their initial response to romiplostim responded to eltrombopag. Sixteen romiplostim responders requested their physicians to switch them to eltrombopag because they preferred an oral drug. The efficacy was maintained after switching in all 16 patients. In the platelet-count fluctuation group, the initial response rate was also 100%. All 4 patients who were switched to eltrombopag because they experienced side-effects of romiplostim achieved complete remission with eltrombopag and their adverse events were resolved. 16 / 51 (33%) patients experienced one or more adverse event during treatment with eltrombopag. The frequency of grade 3–4 adverse events during treatment with eltrombopag was 9.8%. Conclusion: The use of eltrombopag after romiplostim for treating ITP is effective and safe. The reason for discontinuing romiplostim was associated with the response to eltrombopag. Disclosures No relevant conflicts of interest to declare.

Description: Key Points Increased levels of sCD19 protein in the CSF are associated with CNS disease in DLBCL and BL patients at risk of CNS lymphoma. Presence of lymphoma cells by FCM and/or increased CSF sCD19 levels are related with a poorer EFS and/or OS in DLBCL and BL patients.

Description: Introduction : Follicular lymphoma (FL) is an indolent non-Hodgkin lymphoma that represents 15-30% of all newly diagnosed lymphomas. It is characterized by a high rate of response followed by continuous relapses being considered incurable with standard immunochemotherapy regimens (Ardeshna et al. Lancet. 2003). The combination of immunochemotherapy and rituximab maintenance (Rm) improves progression free survival (PFS) when compared with a cohort without Rm (51% vs 35%) (Salles G. et al. ASH, 2017), being the standard for many centers. This improvement may have changed the risk assessment in FL. However, there is a need for identifying those patients with a poor prognosis with standard Rm-based therapy and candidates to receive alternative approaches using new drugs such as obinutuzumab with better reported results in this frontline setting (Gallium trial) (Marcus et al., 2017). Methods : From February-2002 to October-2016, all newly diagnosed FL patients with the intention to treat with immunochemotherapy and Rm where included. The participant centers were Son Espases University Hospital and Hospital del Mar of Barcelona. Clinical data were retrospectively collected from clinical histories and standard prognostic variables were evaluated at diagnosis including FLIPI and FLIPI-2. Another prognostic markers were defined: POD12 (progression of disease at 12 months), POD24 (progression of disease at 24 months) and POD30 (progression of disease at 30 months). The regimen effectiveness was evaluated based on the CT or PET/CT findings. Overall survival (OS) and PFS were determined from the date of the first cycle and they were estimated through Kaplan-Meier. Results: A total of 96 patients were included in the study with a median follow-up of 68 months. Main characteristics of the sample are shown in Tables 1. Briefly, median age was 61 years old, 88% where diagnosed in an advanced stage (III-IV), 36% and 38% presented with high risk (3-5) FLIPI and FLIPI2. Five-year OS and PFS was of 94% and 78% respectively. Univariate survival analysis proved that ECOG and response rate affected PFS and that stage and response influenced OS. In this analysis, no significant relation was found between the studied variables and POD12, POD24 or POD30 except beta2-microglobuline in POD30. Conclusions: Frontline Rm significantly improves outcomes of FL patients. It seems that it is not possible to predict only with clinical variables which patients are in high risk of failure to a standard approach with immunochemotherapy followed by Rm. Additional prognostic factors such as molecular markers may help to identify these patients at risk of failure at the beginning of a first line of immunochemotherapy followed by Rm, and candidates for alternative approaches. Disclosures No relevant conflicts of interest to declare.

Description: The nucleosome is the basic structure of chromatin. Changes in the biochemical composition of nucleosome-associated histone tails are associated with specific gene activation states, and are the target of several antineoplastic agents such as histone deacetylase inhibitors (HDI). Nucleosomes are constrained into loops that are flanked by domains known as matrix-attached regions (MARs). MARs contain DNA topoisomerase II (Topo II) consensus sequences. Topo II is responsible for regulating and maintaining DNA topology and is the target of several antineoplastic agents such as the anthracycline IDA, an effect mediated by the induction of double strand DNA breaks (DSB). We hypothesized that the combination of a Topo II inhibitor and a HDI will have synergistic antileukemia activity. VPA and SAHA are two HDIs currently studied in several clinical trials with known antileukemia activity and tolerable toxicity. To test our hypothesis and to develop future clinical studies, we have analyzed the effect of the combination of IDA, a potent Topo II inhibitor, with VPA or SAHA. We treated the leukemic cells lines MOLT4 and HL60 with increasing doses of IDA (0.5-20nM), SAHA (0.3-3μM) or VPA (0.25-3mM) daily for 3 days. First, using trypan blue viability assays, we identified the IC10 of IDA to be 0.5nM for MOLT4 and 1.5nM for HL60. Doses in excess of 2μM of SAHA or 3mM of VPA resulted in more than 90% decrease in cell viability in both cell lines. Subsequently, SAHA at doses of 0.075-1μM and VPA at 1-3mM were used for the combination experiments with IDA at its specific cell line IC10. At low doses of SAHA (0.075-0.45 μM) and VPA (0.25-1 mM) the combination was shown to have synergistic antileukemia activity by the Fractional Product Method of Webb. These results were confirmed using Annexin V assays. Of importance, growth inhibition was independent of the sequence used. To analyze the effects of this combination on DSB generation, we analyzed using immonocytochemistry and western blot, the induction of γH2AX, a histone variant that has been identified as an early event after the DSBs. SAHA alone induced a modest increase in γH2AX compared to baseline, whereas IDA alone had a significant effect that was not potentiated by the addition of SAHA. Histone H3 and H4 acetylation increased in a dose-dependent manner (2.4–15 fold) with both SAHA and VPA, starting at 0.3μM of SAHA and 0.25mM of VPA. The addition of IDA had no significant effect on histone acetylation. Because of previous data indicating that HDIs may down-regulate the expression of Topo II-alpha, the target of IDA, we have studied using real-time PCR its levels prior and during exposure to the different combinations. SAHA or VPA had no effect on Topo II-alpha mRNA levels whereas IDA induced 2.0–3.5 fold its expression in a dose-independent manner, an effect no altered by the addition of SAHA or VPA. Expression of p21CIP1, that is silenced in both cell lines, was restored by single agent VPA, SAHA or IDA. The combination of these drugs resulted in an additive effect in terms of p21CIP1 induction. Despite this phenomenon, no changes in cell cycle status were observed in these cells. In summary, the combination of IDA and SAHA or VPA has potent in vitro antileukemia effect, and should be studied in clinical trials.

Description: Vorinostat, formerly known as suberoyl anilide hydroxamic acid, (SAHA) is a histone deacetylase inhibitor with potent in vitro antileukemia activity. We conducted a phase I study of two dose schedules of vorinostat: oral three times a day (TID) x 14 days every 21 days; or oral twice a day (BID) x 14 days every 21 days. Patients with relapsed or refractory chronic and acute leukemia or myelodysplastic syndrome (MDS), with adequate renal, hepatic functions and performance status were eligible. Older patients with untreated AML/MDS were also eligible. Forty-one patients were registered and dosed. Median age was 54 years (range 18 to 90), 31 (76%) had AML, 4 (10%) CLL, 3 (7%) MDS, 2 (5%) ALL and 1 (2%) CML. The median number of prior therapies was 2 (range 0–7). The starting dose of the oral TID schedule was 100 mg po TID and it was increased in 50 mg po steps using a 3+3 design. As these patients were thrombocytopenic at baseline due to their underlying disease, thrombocytopenia was not considered to be a dose-limiting toxicity. A dose of 300 mg po TID was considered above the maximally tolerated dose (MTD) with 2 out of 3 patients developing grade 3 toxicity (nausea, vomiting and diarrhea). Subsequently, 7 patients were treated at a dose of 300 mg po BID x 14 days every 21 days. Two patients developed gastrointestinal toxicity (typhlitis) in the setting of profound neutropenia, and the dose was reduced in the next 6 patients to 200 mg po BID x 14 days. No excess toxicity was observed at that dose level. Subsequently, 6 more patients were treated at a dose of 200 mg po TID x 14 days (The MTD of 250 mg po TID X 14 days could not be further evaluated as the 50 mg capsule was no longer available). Only one out 6 patients developed grade 3 toxicity (fatigue). More frequently observed toxicities, regardless of causality, were nausea, vomiting, diarrhea, anorexia, headache, fatigue, typhlitis, and dyspepsia that resolved upon cessation of therapy. Laboratory abnormalities included pancytopenia, hyperglycemia, hypokalemia, hypocalcemia and hypophosphatemia. Overall 9 patients (21%) had objective evidence of response: 1 CR, 2 CRp (CR criteria but no recovery of platelet counts), 1 partial response and 5 complete marrow responses (blasts less than 5%). All responses were observed in patients with AML, and 5 (41%) of these responses were observed at a dose of 200 mg po tid. Histone acetylation was observed in all patients at all dose levels. In summary, the MTD of oral vorinostat is either 200 mg po TID or 200 mg po BID x 14 days every 21 days in patients with leukemia. Significant activity was observed at a dose of 200 mg po TID x 14 days in patients with AML. This single agent activity warrants additional investigation of the role of vorinostat in the therapy of AML and may be guided by the development of informative biomarkers.

Description: The combination of DAC and VPA has synergistic antileukemia activity in vitro. Based on this, we developed a phase I/II study of this combination for patients with leukemia. The dose of DAC was fixed: 15 mg/m2 IV daily x 10. Three dose levels of VPA were studied: 20, 35 and 50 mg/kg orally daily x 10 concomitantly with DAC. The phase I portion of the study followed a classic 3+3 schema. The phase II targeted a response rate of 30%. Patients with relapsed/refractory chronic and acute leukemia with adequate renal, hepatic functions and performance status were eligible. Patients older than 60 years of age with untreated disease were eligible if they were not candidates for higher priority therapies. Fifty four patients have been registered and treated on this study that is now closed to new patient accrual. Median age was 60 years (range 5 to 80). All, but 2 patients with MDS, had AML. Median number of prior therapies was 2 (range 0–5). Thirty patients (56%) had abnormal cytogenetics. No non-hematological VPA dose limiting toxicities were observed during the phase I portion of the study. Therefore the phase II combination consisted of VPA at a dose of 50 mg/kg daily with DAC. Ten patients achieved a CR and 2 a CRP (same criteria as of CR but without complete platelet recovery), for an overall response rate of 22%. The study did not meet any of its planned stopping rules and the maximal number of patients (n=40) was accrued in the phase II portion of the study. Ten out 40 patients (25%) achieved a response in that phase. Two out 12 patients (16%) achieved a response at lower doses of VPA. Five out of 11(45%) previously untreated older patients achieved a CR. The median overall survival (OS) for the whole group was 5.3 months, and it has not been reached for those patients achieving a response. The median duration of response is 8.3 months. Complete cytogenetic responses were observed in 4 out 4 patients with informative karyotypes. A trend toward higher VPA levels was observed in responders (p=0.02). Twelve out 35 (34%) patients receiving VPA at a dose of 50 mg/kg had evidence of histone acetylation compared to 1 out 12 (8%) at lower doses. Histone acetylation was transient. The effects on global methylation were assessed using the LINE assay. Median LINE methylation pretreatment was 44% (range 35.7–57.6%) and it decline to 37.08% (p=0.000) by day 10 to return to baseline by day 28. Methylation of p15, p57, p73, MDR1 and THSB1 was measured pretreatment and serially during therapy. Pretreatment p15 methylation was observed in 36 out 46 patients (78%) with a median value of 18.4% (range 0–80) to decline to 11.7% (range 1.3–67.8), p=0.005, by day 10. Methylation of THSB2 was observed in 19 out 48 patients (39.5%) but it was not affected by the therapy. Methylation of p57KIP2, p73 and MDR1 were rare events in this population. p15 hypomethylation was associated with the the induction of p15 mRNA expression. In summary, the combination of DAC with VPA has significant clinical activity in patients with AML and MDS and effect potentially mediated by the induction of DNA hypomethylation and histone acetylation.