ALBERT

Description: Introduction. Ibrunitib (IBR) is active in chronic lymphocytic leukemia (CLL) patients (pts) with TP53 aberrations. Few data describing the dynamics of TP53 mutated clones under IBR are available. We analyzed a cohort of 40 treatment-naïve and relapsed CLL pts treated with IBR to investigate the dynamics of clonal and subclonal TP53 mutations (TP53-mut). Methods. Forty pts (Table) underwent a longitudinal TP53 monitoring (117 samples) by ultra-deep sequencing (UDS): 26 received IBR + rituximab (IBR+RTX) in first line as part of the GIMEMA LLC 1114 protocol (IBR exposition: 8 months in 7 pts and 14 months in 19 pts) (cohort 1), while 14 received IBR single agent after a median of 1.5 (range: 1-4) chemo-immunotherapy lines (IBR exposition: 2.1 to 4 years in 12 pts) (cohort 2). Samples were analyzed by UDS on a MiSeq sequencer (Illumina, Inc.) to obtain a 5000X coverage/base. For variant calling, the MiSeq Reporter software and an in-house bioinformatics pipeline were applied. All mutations were checked on the IARC TP53 database and those with a variant allele frequency (VAF)

Description: It is well known that cytogenetic abnormalities, the IgVH mutational status, ZAP-70 and CD38 have a significant prognostic role in chronic lymphocytic leukemia (CLL). We therefore designed a 1st line treatment approach for young CLL patients stratified according to the biological features of the disease. Between November 2005 and July 2008, previously untreated CLL patients ≤60 years, with advanced or progressive disease, from 21 Italian centers, were included in this study. High risk (HR) patients were defined by the presence of an adverse biologic profile: a 17p deletion in ≥20% of analyzed cells, or a 11q deletion associated with at least one additional poor prognostic factor (IgVH germline, ZAP-70+ ≥10% or CD38+ ≥7%), or a germline IgVH or mutated VH3-21 status and at least 2 additional unfavorable prognostic factors (ZAP+ ≥10%, CD38+ ≥7%, 6q deletion or trisomy 12). Low risk (LR) patients were defined by the absence of the above mentioned characteristics. For HR patients, treatment consisted of 4 monthly courses of Fludarabine and Campath-1H (FluCam; Flu 30 mg/m2 iv; Campath-1H 30 mg iv, days 1–3). Patients who achieved a response with evidence of residual disease - by CT scan, flow cytometry and/or PCR - received a post-induction therapy including a reduced intensity PBSCs allogeneic transplant or, in the absence of a sibling donor, an autologous PBSC transplant or, in the absence of a sufficient harvest, Campath-1H sc (30 mg weekly for a maximum of 12 weeks). For LR patients, treatment included 6 monthly courses of Fludarabine and Cyclophosphamide (FluCy; Flu 30 mg/m2 iv and Cy 250 mg/m2, days 1–3). Patients with no response after 4 courses, were treated with Campath-1H sc (30 mg weekly for a maximum of 12 weeks). All patients received Darbepoietin alpha in case of anemia, G-CSF and Ciprofloxacin in case of severe granulocytopenia and PC prophylaxis with Bactrim. In addition, patients treated with FluCam underwent weekly CMV antigenemia monitoring and valacyclovir prophylaxis (2g/8h). So far, 74 young patients with advanced or progressive disease fulfilling the above criteria have been included in the study, 41 (55%) with a HR profile and 33 (45%) with a LR profile. Forty-five patients have completed the induction therapy, 24 HR patients and 21 LR patients. A response was observed in 17 HR patients: OR 71%, CR 30%, with 17% of patients obtaining an MRD- status; and in 20 LR patients: OR 95%, CR 57%, with a 19% MRD negativity. The 7 FluCam refractory patients were characterized by the presence of a 17p deletion in 3 cases and by multiple enlarged nodes in 5 (bulky nodes: 3 cases). Grade III–IV granulocytopenia was the most common toxicity after FluCam and after FluCy. However, long-lasting cytopenia was observed only in cases treated with FluCy. Asymptomatic CMV reactivation was detected in 3 cases treated with FluCam. Four patients, all treated with FluCy, have died. The causes of deaths were: febrile granulocytopenia in 2 cases, cerebral hemorrhage in 1 and multiple cerebral abscesses of unknown origin in 1. At present, 9 HR patients who achieved a response to FluCam have undergone a PBSC transplantation (allogeneic 3, autologous 6). In conclusion, the first analysis of this study, focused on young CLL patients with progressive disease stratified according to the biologic profile of the disease, has shown a high CR rate after FluCy given to patients with a LR profile and a considerable response rate with a low number of CMV reactivations after FluCam administered to patients with a HR profile. Factors predicting FluCy-related myelotoxicity warrant further investigation.

Description: Introduction. The fludarabine, cyclophosphamide, rituximab (FCR) regimen is associated with high complete response (CR) rates and a negative residual disease status in a significant proportion of cases and is considered the optimal front-line treatment for fit patients with chronic lymphocytic leukemia (CLL). In addition, long-term follow-up of patients treated with FCR at the MD Anderson Cancer Center, in the multicenter German CLL8 study and at Italian institutions indicate that a sizable fraction of patients characterized by a favorable biologic profile remains free from progression in excess of 10 years. FC combined with ofatumumab (FC-O), a human monoclonal antibody which targets an epitope of the CD20 molecule, has also been associated with a high CR rate. The aim of this study was to evaluate whether a double dose of ofatumumab (O2) combined with FC could improve the CR rate in young (≤65 yrs) and fit patients with CLL. Methods. Sixty-one fit CLL patients from 15 Italian institutions were enrolled in this front-line study and treated with the FC-O2 regimen based on the FC schedule (F 25 mg/sqm i.v. d1-3, C 250 mg/sqm i.v. d1-3) combined with 13 doses of O (300 mg i.v. d14; 1000 mg d21 at the first cycle; 1000 mg d1 and d15 at cycles 2-6 and d28 at cycle 6). As infection prophylaxis, patients received bactrim and peg-filgrastim in order to prevent granulocytopenia. CLL diagnosis, treatment requirement and response were assessed according to the 2008 iwCLL guidelines. Minimal residual disease (MRD) was evaluated by flow cytometry in the peripheral blood (PB) and bone marrow (BM), and also by RQ-PCR in flow negative cases. CT scan evaluation was included in the response assessment. Adverse events (AEs) were graded according to the NCI-CTCAE. Results. The median age of patients was 60 years (range 36-65), Binet stages B and C were recorded in 86% of cases, B-symptoms in 21%, increased β2M values in 74% and bulky nodes (≥5 cm) in 10%. An IGVH unmutated status was recorded in 60% of cases, deletion 13q in 37%, no aberrations in 33%, deletion 11q in 14%, trisomy 12 in 12%, 17p deletion and/or TP53 mutation were found in 10% of cases. At present, the median follow-up of patients is 7 months (range 1-20). Response to treatment has been assessed in 29 patients after a median number of 6 courses of treatment (range 2-6). The overall response rate is 90%, with a CR rate of 69% (20 patients). No evidence of MRD was observed by flow cytometry in both PB and BM in 15/20 CR patients (75%). To date, 11 patients with cytometric MRD negative CR have been evaluated by RQ-PCR and no residual disease was detected in 3. Grade 3-4 granulocytopenia was recorded in 4 patients (7%), a severe infection in 4 (7%) and 5 patients (8%) experienced a severe infusion-related reaction during ofatumumab administration. Treatment was discontinued in 8 patients as a result of toxicity (infection, 2 cases; FUO, 1; infusion-related toxicity, 1; autoimmune hemolytic anemia, 1; recurrent granulocytopenia, 1; tachyarrhythmia, 1; non-specified toxicity,1). A non-treatment-related death (traumatic aortic transaction due to a dislocated aortic endoprostheses) has been recorded in a patient after 2 months from treatment discontinuation and 1 showed a disease progression after 4 courses of FC-O2. Conclusions. Taken together, the first analysis of this ongoing front-line study suggests that the combination of FC with an increased dose of ofatumumab is well tolerated with acceptable and no unexpected toxicity. Our preliminary results show that the FC-O2 treatment is associated with a high rate of cytometric MRD-negative CR in young and fit patients with previously untreated CLL. Disclosures Carella: Seattle Genetics Inc.: Research Funding. Foà:Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

Description: Conventional cytogenetics and molecular analyses allow to stratify acute myeloid leukemia (AML) patients into subgroups with different clinical and prognostic relevance. AMLs with unsuccessful cytogenetics and no known recurrent mutations are a subgroup of cases for which information on possible underlying genetic lesions of the leukemic cells is lacking and with a poorly defined outcome. Previous studies have quantified the rate of unsuccessful karyotyping in approximately 10% of the analyzed AML samples and it is conceivable that if cases with molecular rearrangements were to be included this figure could be lower. With the aim of investigating the prevalence and impact of cases with an undefined genetic profile (UGP), we studied 437 AML patients - 228 males and 209 females, with a median age of 50 years (range 1-81) - treated on successive intensive chemotherapy protocols at our Institution. Conventional cytogenetic and molecular analyses - RUNX1-RUNX1T1, CBFB-MY11, DEK-NUP214, FLT3-ITD, NPM1, BCR-ABL, MLL-PTD - were performed at diagnosis. According to the genetic alterations, patients were comprehensively stratified into three subgroups: a favorable risk group - t(8;21) RUNX1-RUNX1T1, inv(16) CBFB-MY11, normal karyotype with mutated NPM1 without FLT3-ITD - with a 5-year overall survival (OS) of 65%, an intermediate risk group - normal karyotype with mutated or wild type NPM1 and FLT3 ITD or wild-type NPM1 without FLT3-ITD, t(9;11)(p22;q23), cytogenetic abnormalities not classified as favorable or adverse - with a 5-year OS of 27% and an unfavorable risk group - inv(3)(q21q26) or t(3;3)(q21;q26), t(6;9)(p23;q34), DEK-NUP214, t(v;11)(v;q23), -5 or del(5q), -7, complex karyotype - with a 5-year OS of 11%. Thirty-three patients (7.5%) were identified as having an UGP and their baseline characteristics, as well as clinical outcome, were compared to those of patients with defined molecular and cytogenetic features. Patients with an UGP were older at the onset of the disease than those with a delineated genetic profile (median 55 vs 49 years). In addition, the proportion of UGP cases increased with age, being 3% in patients 50 years. The complete remission (CR) rate for UGP patients (69.6%) was similar to that of intermediate risk patients (71.1%), but inferior to that of patients with a favorable risk profile (90.5%) (p=0.0046) and better than that of unfavorable genetic risk patients (63.7%). After adjusting for age, gender, WBC and platelet count, Hb, marrow blast percentage at diagnosis and treatment, UGP remained an independent factor for lower CR rate with respect to patients with a favorable genetic risk profile. The frequency of relapse was significantly higher in patients with UGP compared to the favorable risk group (60.8% vs 32%) (p=0.011). In multivariate analysis, the 5-year OS of patients with UGP was significantly worse than that of patients with a favorable genetic risk profile (p

Description: Abstract 4408 PNH is a hemolytic disorder resulting from dysregulation of complement on the rbc, and is associated with immune mediated marrow failure and marked hypercoagulability. Thrombosis can be prevented with anticoagulation or the complement inhibitor eculizumab, and it often involves the hepatic, portal, and splenic veins. This can result in an increase in portal pressure and complications that we term the “Thrombosis-Splenomegaly-Thrombocytopenia” syndrome (TST). TST is frequently associated with abdominal pain, and thrombocytopenia may be simultaneously exacerbated by marrow failure. Particularly, thrombocytopenia can complicate efforts at anticoagulation, leaving the patient exposed to the risk of further events. In some patients thromboses can reversed with tPA, but others will not be candidates because they have presented late after their thromboses. Ablating splenic function would be desirable: however, with a high risk of perioperative thrombosis, surgical splenectomy may be hazardous, particularly in patients who have already had thrombosis, and will confer a risk of sepsis. Here we report on 4 patients with PNH and late-presenting TST. We referred these 4 patients for selective splenic artery embolization (SSAE), which involves cannulating branches of the splenic artery– beyond the hilum– and introducing gelfoam and microcoils. We planned a multi-session stepwise approach: we started with the inferior branches of the splenic artery, to decrease the risk of pleural effusions. We planned to infarct no more than 1/3 of the spleen at any one time and to allow weeks to months for recovery. We routinely administered vaccinations and discontinued anticoagulation temporarily, and patients were given prophylactic antibiotics, fluids, analgesics, and antipyretics, and they were observed in the hospital with a back-up surgical team. Prior to the procedure, the median platelet count was 17 and the median spleen size was 22 cm. Patients 1–4 were treated with 3,2,1, and 3 procedures respectively, which resulted in a significant reduction in spleen volume in all 4 patients. The post procedure platelet counts were respectively 123, 12, 44, and 90, which represented a significant increase for all patients except patient 2, who remained thrombocytopenic; since there was evidence of bone marrow failure, she underwent a successful unrelated SCT. Patients 1,2, and 4 all had had abdominal pain before the procedure, which very significantly improved after recovery from the procedure, which we attribute to decreased venous return from the spleen into the portal circulation. Patients 1–3 were treated before eculizumab was available and patient 1, 3, and 4 are now on it. Patient 4 is a special case in that she had been on eculizumab for several months prior to the SSAE, but had had only a partial reduction in the red cell transfusion requirement; C3d deposition on rbcs was documented by flow cytometry, and it was thought that extravascular hemolysis was limiting her response to eculizumab, as has been described. Of note, her hemoglobin began to rise after the embolization procedure, concurrent with the increase in the platelet count, and a significant further reduction in the red cell transfusion requirement, suggesting that partially reducing splenic function markedly reduced C3-mediated extravascular hemolysis. Of the 9 procedures performed on these 4 patients, only one was complicated by a clinically significant left sided pleural effusion, which was drained by thorascope. All patients are doing well between 3.5 and 11 years after their procedures. We conclude that SSAE, when performed by an experienced interventional radiologist, is relatively safe in patients with PNH and TST, it produces sustained correction of hypersplenism without the risk associated with surgery or the asplenic state, and can be of benefit to patients on eculizumab who have hypersplenism. Pt Age at diagnosis Lowest plt count pre-SSAE Spleen size (cm) pre-SSAE Abdominal pain pre-SSAE Bone marrow Plt count post SSAE Spleen size post SSAE Abdominal pain after recovery from SSAE Complications of SSAE Follow up (yrs) 1 30 42 21 + Hypercellular Megakaryocyte aggregates 123 12 No Abd pain and fever 10 2 18 19 19 + Hypocellular Megas reduced 12 12 No Pain, pleural effusion SCT 3 27 14 36 – Erythroid hyperplasia Megas adequate 44 NA No Abd pain 11 4 26

Description: Abstract 2462 Background: Two of the largest trials ever conducted in patients with chronic lymphocytic leukemia (CLL) have shown that the addition of rituximab to fludarabine plus cyclophosphamide (R-FC) significantly improves outcome. However, myelotoxicity and immunosuppression limit the use of this regimen in patients with impaired performance status and pre-existing co-morbidities, predominantly in the elderly. Chlorambucil (CLB) remains a first-line treatment option for such patients. The use of CLB in combination with R is thus an attractive therapeutic option in view of the potentially increased activity compared to CLB alone and the likely good tolerability. This study was designed to determine whether the R-CLB combination is feasible and beneficial as first-line treatment for elderly patients with CLL and to define the role of maintenance R. Patients and Methods: Between October 2008 and January 2010, 97 elderly patients with untreated CD20+ CLL requiring therapy according to the IWCLL criteria were enrolled into the protocol. CLB treatment was administered every 28 days for up to 8 courses at a dose of 8 mg/m2/day p.o. on days 1–7 combined with 375 mg/m2 R for cycle 3 and 500 mg/m2 for cycles 4–8. Responsive patients were randomized to R maintenance (375 mg/m2 every 2 months for 2 years) versus observation. At baseline, blood samples were taken for FISH analysis, IgVH mutational status and expression of Zap-70 and CD38. Minimal residual disease (MRD) was planned to be evaluated on peripheral blood (PB) and bone marrow (BM) cells by four-color flow cytometry and, when required, by PCR. The primary endpoint was the overall response rate at the end of the induction phase defined according to the IWCLL 2008 on the intention-to-treat (ITT) population (all enrolled patients who received at least 1 dose of R). Secondary endpoints included the adverse event (AE) profile, progression-free and overall survival. Results: These are the data of the planned interim analysis based on the first 54 evaluable patients from 19 Italian centers, including tumor response at the end of the induction phase and safety. The median age of patients was 70.5 years (range 61–84): 14.8% were between 61 and 64, 31.5% between 65 and 69, 31.5% between 70 and 74, 16.7% between 75 and 79, and 5.6% were ≥80 years; thus, 53.8% of patients were over the age of 70; 70.4% were males; 25.9% were Binet stage A, 57.4% stage B and 16.7% stage C. The overall incidences of trisomy 12 and abnormalities of 13q, 11q23 and 17p13 were 24.5%, 52.8%, 20.8% and 5.7%, respectively; 7.5% of patients had p53 mutations. Of the 51/54 patients analyzed for the IgVH mutational status, 64.7% were unmutated; of the 53/54 patients studied, 39.6% were CD38+ and 71.7% were Zap-70+. The overall response rate on an ITT analysis was 81.4% (44/54 patients); a CR assessed by CT scan and trephine immunohistochemistry was found in 16.7% of cases (9 patients: 4 in Binet stage A, 3 in stage B and 2 in stage C), a CRi in 3.7% (2 patients), a nPR in 1.9% (1 patient) and a PR in 59.3% (32 patients). Eight of the 9 CR cases were investigated for MRD by flow cytometry and all proved positive: 6/8 had MRD levels

Description: Dasatinib is a potent BCR-ABL inhibitor effective in chronic myeloid leukemia and Ph+ acute lymphoblastic leukemia (ALL) resistant/intolerant to imatinib. In the GIMEMA LAL1205 protocol, patients with newly diagnosed Ph+ ALL older than 18 years (with no upper age limit) received dasatinib induction therapy for 84 days combined with steroids for the first 32 days and intrathecal chemotherapy. Postremission therapy was free. Fifty-three patients were evaluable (median age, 53.6 years). All patients achieved a complete hematologic remission (CHR), 49 (92.5%) at day 22. At this time point, 10 patients achieved a BCR-ABL reduction to 〈 10−3. At 20 months, the overall survival was 69.2% and disease-free survival was 51.1%. A significant difference in DFS was observed between patients who showed at day 22 a decrease in BCR-ABL levels to 〈 10−3 compared with patients who never reached these levels during induction. In multivariate analysis, BCR-ABL levels of 〈 10−3 at day 85 correlated with disease-free survival. No deaths or relapses occurred during induction. Twenty-three patients relapsed after completing induction. A T315I mutation was detected in 12 of 17 relapsed cases. Treatment was well tolerated; only 4 patients discontinued therapy during the last phase of the induction when already in CHR. In adult Ph+ ALL, induction treatment with dasatinib plus steroids is associated with a CHR in virtually all patients, irrespective of age, good compliance, no deaths, and a very rapid debulking of the neoplastic clone. This trial was registered at www.clinicaltrials.gov as #NCT00391989.

Description: BCR-ABL antisense oligodeoxynucleotides (ODN) have provided evidence of antileukemia effect when tested in vitro against Philadelphia-positive (Ph-pos) cells and in vivo when injected into leukemic mice. On the basis of the results obtained in vitro at diagnosis, eight patients with chronic myelogenous leukemia (CML) were selected and submitted to autologous bone marrow transplantation (ABMT) with bone marrow (BM) cells purged in vitro with junction-specific (J-sp) BCR-ABL antisense ODN at the time of transformation in accelerated phase or during second chronic phase. Mononuclear BM cells were treated in vitro for 24 or 72 hours with 150 μg/mL of antisense ODN yielding a median recovery of 47.6% mononuclear cells, 48.8% CD34+ cells, and 20.3% clonogenic cells. After a conditioning regimen including busulphan and etoposide, the reinfused treated cells allowed engraftment and hematologic reconstitution in all patients. Evaluation of the antileukemic effect by standard cytogenetic analysis and fluorescence in situ hybridization showed a complete karyotypic response in two cases and a minimal or no response in the other six. The patient autografted in second chronic phase died in blast crisis 7 months after ABMT; of the seven patients autografted in transformation, three developed blast crisis 21 to 39 months after reinfusion, one died from unrelated BMT complications 30 months after ABMT, and three are in persistent second chronic phase 14 to 26 months after autograft. The low toxicity of the protocol and the hemopoietic reconstitution observed in all patients make this approach feasible; the marked karyotypic response observed in some patients and the duration of the second chronic phase show that ODN-mediated BM purging and autograft is a promising treatment for this high-risk group of CML.

Description: Abstract 4085 Poster Board III-1020 Introduction Umbilical cord blood (CB) stem cells are now broadly used in the unrelated stem cell transplant setting and comparative studies with different stem cell sources have shown that CB transplant is characterized by a lower risk of graft-versus-host disease (GVHD). The immaturity of CB T cells has been generally regarded as the main contributing factor accounting for this phenomenon; the possible role played by CB regulatory T cells (Tregs) for the suppression of the allogeneic T-cell response is now under investigation, but very scare data are so far available. Aim of this study was to analyze and compare the functional properties and the gene expression profile of Tregs expanded from CB units with those expanded from the peripheral blood (PB) of adult normal donors. Methods Tregs were purified from mononuclear cells obtained from 23 CB units and from the PB of 13 adult normal donors using the CD4+CD25+ regulatory T-cell isolation kit (Miltenyi Biotec) and expanded for 6 days in 96-well U-Bottom plates coated with the anti-CD3 (5 ug/ml) and anti-CD28 (5 ug/ml) MoAbs in the presence of IL-2 (100 U/ml). Immunophenotypic analyses were performed before and after expansion. To assess their suppressive functions, expanded Tregs were seeded with autologous effector T cells stimulated with allogeneic dendritic cells (DC) pulsed with apoptotic leukemic blasts, then incubated with [3H]-thymidine and counted in a beta-counter. Suppressor activity was measured as [3H]-thymidine incorporation in the presence or absence of Tregs. The IL-10 production capacity of expanded Tregs was tested using an ELISA assay. The two-sided student t test was used to evaluate the significance of differences between groups. Gene expression profile experiments were performed using the HGU133 Plus 2.0 arrays (Affymetrix); statistical analyses were carried out using the dChip software; a t test was used to evaluate the presence of specifically expressed classes of genes. Functional annotation analysis was performed using the DAVID software. Results CB and PB Tregs presented similar immunophenotypic appearances before and after expansion. Im particular, after expansion they presented a comparable expression of surface CD4, CD25, CD62L, CCR5 and CD45RO, and of cytoplasmic CTLA-4 and Foxp3, while they both were negative for the CD45RA antigen, thus indicating the loss of their naïve features. On the contrary, Tregs obtained from CB (n=23) presented a much higher expansion capacity compared to those obtained from PB (n=13): mean fold increase (range), CB 10.3 (1.6-24), PB 3.9 (1.5-10), p 0.003. CB expanded Tregs (n=6) exerted a potent suppressive function on the proliferative reaction of T cells stimulated by allogeneic DC, that resulted inferior even though not significantly compared to that exerted by PB expanded Tregs (n=5): mean fold reduction (range), CB 7.8 (2.5-15.1), PB 14.3 (1.5-23.7), p 0.14. Tregs expanded from CB (n=4) and PB (n=1) presented a high and comparable in vitro IL-10 production capacity: mean pg/ml (range), CB 326.5 (226-426), PB 382. Gene expression profile analysis showed a higher number of upregulated genes in Tregs expanded from CB (n=2) compared to Tregs expanded from PB (n=3); among them, a significant enrichment of genes involved in cell proliferation, cell cycle checkpoints, signal transduction, cell differentiation, apoptosis, TGF-β receptor pathway and the GrNH pathway was observed. This suggests that CB Tregs retain a more undifferentiated program and are characterized by the high expression of genes which might provide an advantage in cell expansion. Finally, when looking at the Foxp3 gene expression levels, no difference was observed between the two populations. Conclusions These results demonstrate that Tregs contained in CB retain an expansion potential superior to that of Tregs isolated from the PB of normal donors, as confirmed by functional analyses and gene profile. Tregs expanded from CB and PB seem to exert a potent and comparable suppressive function of the proliferative effect in mixed lymphocyte reaction assays. The maintaining of the modulatory properties after expansion is confirmed by the expression of the Foxp3 gene and protein, and by the production of IL-10. These data offer further insights into the understanding of the biology of CB transplantation indicating a possible role played by CB Tregs in the suppression of the allogeneic T-cell response. Disclosures: No relevant conflicts of interest to declare.

Description: BCR-ABL antisense oligodeoxynucleotides (ODN) have provided evidence of antileukemia effect when tested in vitro against Philadelphia-positive (Ph-pos) cells and in vivo when injected into leukemic mice. On the basis of the results obtained in vitro at diagnosis, eight patients with chronic myelogenous leukemia (CML) were selected and submitted to autologous bone marrow transplantation (ABMT) with bone marrow (BM) cells purged in vitro with junction-specific (J-sp) BCR-ABL antisense ODN at the time of transformation in accelerated phase or during second chronic phase. Mononuclear BM cells were treated in vitro for 24 or 72 hours with 150 μg/mL of antisense ODN yielding a median recovery of 47.6% mononuclear cells, 48.8% CD34+ cells, and 20.3% clonogenic cells. After a conditioning regimen including busulphan and etoposide, the reinfused treated cells allowed engraftment and hematologic reconstitution in all patients. Evaluation of the antileukemic effect by standard cytogenetic analysis and fluorescence in situ hybridization showed a complete karyotypic response in two cases and a minimal or no response in the other six. The patient autografted in second chronic phase died in blast crisis 7 months after ABMT; of the seven patients autografted in transformation, three developed blast crisis 21 to 39 months after reinfusion, one died from unrelated BMT complications 30 months after ABMT, and three are in persistent second chronic phase 14 to 26 months after autograft. The low toxicity of the protocol and the hemopoietic reconstitution observed in all patients make this approach feasible; the marked karyotypic response observed in some patients and the duration of the second chronic phase show that ODN-mediated BM purging and autograft is a promising treatment for this high-risk group of CML.