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Background: The GATLA Collaborative Group has a 50 year (y) long experience of running cooperative trials for lymphomas in Argentina. Aim: Describe the outcome of pediatric patients(pts) treated according to the international cooperative work with AHOPCA and St. Jude Children's Research Hospital (11-EHP-12) adopting OEPA/COPDAC strategy for High Risk (HR) pts and ABVD for Intermediate (IR) and Low Risk (LR) pts. Methods: 11-EHP-12: Risk assignment according Stanford/Danna Farber/ SJCRH Consortium classification. LR: ABVD x 4± IFRT (20 Gy). IR: ABVD x 6 ± IFRT (20 Gy). HR: OEPA-COPDAC+IFRT (20/25 Gy). Response evaluation: LR after 4th cycle, IR and HR after the 2nd cycle. Complete Remission (CR): response > 80% reduction and PET negative. Partial Remission (PR): response >50% and Results: 5 y OS was 94% (100% for LR and IR, and 91% HR) and 5y EFS was 88% (100% for LR, 91% IR, and 84% HR). 95% of the LR pts and 72% of the IR pts did not undergo radiotherapy. 70% of the HR pts achieved CR after the 2nd OEPA and received 20 Gy IFRT. According PR or CR after 2nd OEPA, the 5y EFS in HR pts was 84% and 90% respectively. Conclusion: Thanks to this international cooperation We could significantly improve the results in Argentina compared to our previous experience (7-PHD-96: COPP-ABV x 6 + IFRT Bulky disease or PR (20/25Gy): 5yOS:85%, 5yEFS:67%), reduce the number of patients who required radiotherapy and reproduce the Euronet experience for HR pts in a different context. Figure Disclosures No relevant conflicts of interest to declare.

Abstract 2605 Introduction: The outcome in pediatric patients with relapse-refractory acute leukemia (acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML)) is very poor. Clofarabine is an active agent in this high risk group. Purpose: Report the GATLA experience in patients with relapse-refractory acute leukemia treated with clofarabine based regimens. Methods: Between June 07 and April 12, 66 patients from 15 GATLA centers were enrolled. 61 ALL (52 B/9 T): 23 first relapse (20 BM, 1 CNS, 2 combined), 33 second relapse (28 BM, 1 CNS, 4 combined), 5 with refractory disease. 5 AML (4 first relapse, 1 refractory disease). Median age 10,5 years (1–20 ys). Gender: 44 boys and 22 girls. 60 patients received chemotherapy combined clofarabine-etoposide-cyclophosphamide (CLO 218), 4 patients received clofarabine plus ara-c therapy and 2 patients were treated with clofarabine alone (52mg/m2). 63.7% (42/66) of the patients were treated with 2 therapeutic lines prior to clofarabine regimens, 22.7% (15/66) received only 1 prior treatment, 13.6% (9/66) got 3 or more therapies and 5 patients undergone prior HSCT (Hematopoietic Stem Cell Transplantation). Results: Complete remission (CR) was achieved in: 36/66 patients (54,5 %). Early toxic death rate was 7/66 (10,6%). No response occurred in 22/66 (33,3%) patients. 1 patient is on induction, not evaluable at the moment. Of the 36 responders, 19 patients (52,7 %) proceeded to HSCT: 6 (31,5 %) remain alive post-transplantation with a median follow up of 55 weeks ( range 6–156 w), HSCT related death: 7 (37 %), relapse after HSCT: 6 (31,5%) at a mean of 20 weeks( range 8–56 weeks). Among the 61 ALL patients, 18/23 (78%) in first relapse achieved CR, 12/18 (66,6%) needed only one course to achieved CR, of them, 3/12 (25%) relapsed at 8, 8 and 14 weeks and died for progressive disease. 1/12 (8,3%) died in CR at week 8. 2/12 (16,6%) patients are on treatment. 6/12 (50%) proceeded to HSCT: 1/6 relapsed 56 weeks after. 3/6 patients died in CR after HSCT at 12, 15 and 24 weeks. 2/6 remain in CR at 6 weeks follow up. 6/18 (33,3%) of the patients in first relapse needed 2 courses to achieved CR. 1/6 (16,7%) relapsed at week 8. 2/6(33,3%) died in CR at week 9 and 16. 3/6 ( 50%) proceeded to HSCT, 1 is alive at 36 weeks, 1 relapsed at week 26 and 1 died in CR at week 14. 13/33 (39%) ALL patients in second relapse achieved CR and 8/13 (61,5%) needed only one course to CR. 3/8 (37,5%) relapsed at 6,8 and 16 weeks and died for progressive disease. 5/8(62,5%) proceeded to HSCT, of them 3 (60%) relapsed after HSCT at 8,8 and 12 weeks. 1/5 (20%) is alive and disease free at 6 weeks after HSCT. 1/5 (20%) died in CR. 5/13 (38%) needed 2 courses to achieved CR, 1/5 relapsed after 4 weeks. 1/5 died in CR at week 6, 1/5 is alive 40 weeks after CR. 2/5 proceeded to HSCT and died in CR at 10 and 22 weeks after HSCT. 2/5 ALL patients with refractory disease achieved CR with 2 and 3 courses of clofarabine, one proceeded to HSCT and is alive with a follow up of 156 weeks, the other relapsed at 8 weeks. 3/5 did not response and died. AML patients: 3/5 received clofarabine as 3rd therapeutic line: 1 patient achieved CR after one course but died of toxicity, 1 patient did not response and 1 died during induction. 2/5 received clofarabine as 2ndline ( 1 with refractory disease and 1 who undergone prior HSCT), they achieved CR with 2 courses of chemotherapy and proceeded to HSCT, one relapsed after 16 weeks and the other is alive and disease free after 120 weeks. Conclusion: In our series, Clofarabine was well tolerated and shows significant antileukemic activity in heavily pretreated children. The response rate and the durability of remission observed is better when clofarabine regimens are used earlier (first relapse). Responses allowed several refractory patients to proceed to HSCT. Levels of pre transplant MRD (Minimal Residual Disease)should be taken into account in order to follow this procedure. Disclosures: No relevant conflicts of interest to declare.

Abstract 4716 Background Conventional cytogenetic studies by chromosome banding are difficult in chronic lymphocytic leukemia (CLL) because of the low in vitro proliferation or mitotic activity of CLL cells. Interphase Fluorescence in situ hybridization (FISH) has improved the detection of genomic aberrations in CLL. We used this method to identify chromosomal abnormalities in patients with CLL at diagnosis, progression disease, after relapse or treatment failure. Methods Mononuclear cells from the blood of 24 Caucasian patients, 12 men and 12 women, age ranged from 39 to 84 years (median, 64) with CLL were analyzed by FISH, for deletions in chromosome bands 11q22.3, 6q23.3, 13q14.3, 17p13.1, and trisomy of chromosome 12. The patients stages were 0A:12; IA:1; IIA: 2; IIB:4; IIIA:1, IIIB:1; IIIC:1; IV:2. The follow up ranged was from 7 to 124 months. Results Chromosomal aberrations were detected in 15 of 24 (58.33 percent). The most frequent changes were a 12 trisomy (37.5 percent), a deletion in 11q23.3, (12.5 percent), a deletion in 6q23.3 (8.33 percent), a deletion in 17p13.1 ( 8.33 percent), a deletion in 13q14.3 8.33%. A patient showed four aberrations tri(12), d(17p13.1), d(6q23.3), d(11q23.3), she was resistant to Fludarabine + Cyclophosfamide treatment and Rituximab CHOP and had a survival of 51 months. The other patients with trisomy 12 alone are still alive and the survival were ranged from 7 to 120 month. Trisomy 12 was correlated with enlarged lymph nodes. Two patients undergo Richter transformation one of them with 6q23.3 the other without the aberrations assessed. The patients with deletion 11q23.3 were resistant to standard regimens treatment. Ten patients have stable disease (0A), clinical follow up ranged from 7 to 124 months; three with trisomy 12 the others without the genetic aberrations assesses. Longest survivals (124 month) were found in patients without aberration or with trisomy 12. Patients without aberrations or with trisomy 12 had similar evolution. A female patient, 84 years old state in stage 0A along 13 month with d(17p13.1), and d(11q23.3). Patients with 11q23.3 deletions had the shortest median treatment-free interval (11months), and those with trisomy 12 or deletion 13q14.3 had the longest (124 and 40 months respectively). Patients with 11q23.3 and 6q23.3 deletion had more advanced disease. Two patients died, both of them with 6q23.3, overall survival 51 and 54 months respectively. ZAP 70 and CD38 do not have correlation with presence of the genomic aberration assessed .The present of 11q23.3, 6q23.3, 17p13.1, age, the white-cell count, Rai - Binet stage and the serum lactate dehydrogenase level gave significant prognostic information. Conclusions Genomic aberrations are independent prognosis factors of disease progression and survival in Chronic lymphocytic leukemia; establish them properly will be an important goal standard, therefore incorporate FISH assay routinely could give significant prognostic information. These genetic findings are predictors of outcome treatment regimens and could help to choose the appropriated strategic treatments. Disclosures: No relevant conflicts of interest to declare.