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Abstract 1508 Background. The long term prognosis of ETV6/RUNX1 -positive acute lymphoblastic leukemia (ALL) remains to be evaluated with regard to the frequency of late relapses and the possible existence of a preleukemic stem cell. We performed a retrospective study based on a long-term follow up of the FRALLE 93 ALL relapses to address the issue of the outcome of ETV6/RUNX1 -positive ones. Methods. 1395 patients aged 0 to 20 years with untreated ALL (except L3) were included between 01-Jan-1993 and 31-Dec-1999. From 1995, children were systematically screened for four fusion transcripts (ETV6-RUNX1, BCR-ABL, E2A-PBX1, MLL-AF4). The FRALLE 93 study population was stratified into three groups (low-risk [LR], intermediate-risk [IR], and high-risk [HR]) based on the following prognostic factors: age, white-cell count at diagnosis, haemoglobin level, immunophenotype, karyotype, and response to steroids. Patients received an initial treatment comprised of a prednisone prophase and a triple-drug intrathecal injection. Induction treatment then included prednisone, vincristine, L-asparaginase, daunorubicin (except for the LR group), and one or two more triple-drug intrathecal injections (TIT). The main treatment features of the SR and IR protocol were induction, consolidation, delayed intensification, and maintenance (total treatment duration of 26 and 38 months for girls and boys respectively). Treatment of the HR patients consisted of induction, consolidation, two delayed intensifications, and maintenance with a total treatment time of 2 years. Depending on subgroups, CNS-directed therapy included intrathecal injections +/− high-dose methotrexate +/− cranial irradiation. Following factors influencing survival after first relapse were analyzed: age, leukocytosis, gender, duration of first remission (CR1), risk groups defined in the REZ-BFM 95/96 study, sites of relapse and post CR2 consolidation treatment (AlloSCT or not). Results. ETV6/RUNX1 status was defined for 724 patients B lineage ALL. Overall, 162 of the 713 children who reached CR1 (45 % of boys) relapsed, including 43 with t(12;21). Cumulative incidence of relapses did not differ between ETV6/RUNX1 -positive and negative ALL (p=0.94), with a 5-year estimate at 19.4% and 19.9%, respectively nor according to gender and type of relapse. Nevertheless, 11 out of 26 relapses in the ETV6/RUNX1 -positive ALL males (43%) were testicular (4 testis isolated) versus 16 out of 70 (23%) in ETV6/RUNX1 -negative ALL cases (p= 0.04). Thirty three (77%) had been stratified as LR (n=6) or IR (n=27) group and 32 displayed good early response at initial diagnosis. Thirty five (81.4%) patients were classified as S1/S2 and 8 (18.6%) as S3/S4. All but three received second line salvage therapy (37/40 were included in the COOPRALL 97) and 16 underwent an AlloSCT (6 S3/S4). Based on univariate analyses, the overall survival of ETV6-RUNX1 -positive ALL after relapse was significantly affected by the duration of the first remission with a OS that was significantly improved when relapse occurred after 36 months (5-year OS: 80.6+/−7.9% versus 34.7+/− 12.3, p=0.002). Female gender was also associated with a poor survival (p= 0.015), whereas the site of relapse (p= 0.13), age at initial diagnosis (p= 0.81), leukocytosis (p=0.42), and consolidation strategy (p=0.18) had no affect on survival. In multivariate Cox-regression analysis, only the duration of first remission remained associated with the outcome (Figure 1). Conclusions. We found a high rate of testicular relapse without any increase of other extramedullary sites and an excellent outcome for ETV6/RUNX1 -positive leukemia relapses occurring over 36 months post-diagnosis. These findings highlight the interest of a primary treatment able to cross the testicular barrier. They also support the hypothesis that ETV6/RUNX1 “late relapses” are due to a novel leukemic clone, sensitive to a novel cycle of ALL chemotherapy. Disclosures: No relevant conflicts of interest to declare.

Abstract 534 Introduction: There is increasing information about reduced intensity conditioning regimen AlloHSCT (Allogeneic Hematopoietic Stem Cell Transplantation) in children. The safety of this approach is now well established but data regarding efficacy are limited and the role in pediatric cancer has yet to be defined. Materiels and methods: We report results of a French pediatric AlloHSCT protocol with ATG-fludarabine (180 mg/m2) - Busilvex (3.2 at 4.8 mg/kg/d for 2 days) conditioning regimen. Related, unrelated bone marrow (BM) and Peripheral blood stem cell (PBSC) donors and Cord blood units (CB) were allowed. In case of CB a TBI 2 grays, Cyclophosphamide 50 mg/kg, Fludarabine 100 mg/m2 conditioning regimen was recommended. GVH prophylaxis consists in cyclosporine alone. A rapid discontinuation of systemic immunosuppression and re-injecting donor lymphocytes to initiate graft-versus-tumor effect are based on tumor assessment and blood chimerism. Inclusion criteria are children with malignancies that can be potentially cure by allograft but a conventional conditioning regimen being impossible due to toxicity and children with solid tumor or hematological malignancy remaining unresponsive to the reference strategies according to French best practices in pediatrics. Results: From April 2007 to April 2010, 40 RIC AlloHSCT were performed in 10 different French pediatric graft centers: 13 Hodgkin Lymphoma, 7 acute myeloblastic leukaemia, 2 acute lymphoblastic leukaemia, 6 neuroblastoma, 8 rhabdomyosarcoma, 3 desmoplastic tumor and 1 Ewing sarcoma. Median age at transplantation was 15 years and median time from diagnosis to transplant was 18 months. Before transplant, 15 patients are in complete response and 25 patients (14/18 solid tumors) have active disease (11 progressive, 14 partial response). 21 had already received a myeloablative therapy (18 autograft and 3 allograft). Graft source was PBSC in 17 cases (7 related and 10 unrelated), BM in 18 (10 related and 8 unrelated), and 5 CB. The RIC Bu-flu conditioning regimen permits rapid engraftment without major toxicity contrary to the Cy-TBI in CB. 1 patient had primary graft failure: 1 CB and 5 patients experienced secondary graft failure: 3 CB, 1 PBSC and 1 BM. Median time to reach an ANC of 0.5 109/l was 16 days. Median time to reach a platelet count of 20 × 109/l was 2 days. Platelet count did not decrease below 20 109/l in 10 allografts. At day 30 post-transplant, chimerism is mainly donor for 30 and partial for 6 children. At day 100 post transplant, 4 out of 6 with initial mixed chimerism were converted into full donor chimerism. 8 patients received DLI and 17 patients experienced acute graft versus host disease (GvH) (2 grade IV and 15 grade ≤ II). A low day 365 TRM of 5% is reported in these heavily pre-treated patients. With a median follow-up of 15 months, the estimated 2 yr overall survival (OS) was respectively 57 % (71% for hematological malignancies and 42% solid tumors) (fig 1) and event free survival (EFS) 36% (50% for hematological malignancies and 19% solid tumors). Univariate analysis of EFS and OS showed no effect of related versus unrelated stem cell sources and BM versus PBSC. Our analysis identified a group of patients, who had no measurable disease at transplant, with a 2 yr OS and EFS of 86%. In term of efficacy, we observe a graft versus lymphoma effect in patients with advanced active Hodgkin lymphoma. Concerning solid tumors, all children included had a very bad prognosis and detectable disease before transplant. Our results may suggest that an immune-mediated effect cannot be excluded in some refractory solid pediatric tumors particularly in neuroblastoma. The main cause of failure of this approach is disease progression. Immunologic approaches after transplantation may help cure more of these very-high-risk patients. Conclusion: Even if further follow up is needed, this prospective study suggest that RIC regimen provides promising outcome in children previously not eligible for myeloablative AlloHSCT. This study “RICE” was registered at www.clinicaltrials.gov as NCT 007 50 126 Disclosures: No relevant conflicts of interest to declare.

Abstract 3518 Background: Despite progress made in sickle cell anemia (SCA) management, such as the prevention of pneumococcal infections, introduction of hydroxyurea therapy and early cerebral vasculopathy detection with transcranial Doppler, SCA remains a disease with high risk of morbidity and early death. Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative treatment for SCA; nevertheless, its use has been limited by the risk of transplant-related mortality (TRM). Our first experience, reported in Blood 2007, included 87 consecutive severe SCA- patients transplanted in France between 1988 and Dec-2004. We showed that the introduction of rabbit anti-thymocyte globulin (ATG) in the conditioning regimen in 2000 allowed a significant reduction of the rejection rate from 22.6% to 3% and that the outcome improved significantly with time as the DFS rate among the 44 patients transplanted after January 2000 was 95.3%. These data have justified continuing to transplant symptomatic young sickle cell patients having a geno-identical donor with the same conditioning regimen (CR) consisting of intravenous Busulfan (BU), Cyclophosphamide (CY) and rabbit ATG. Patients and Methods: In France, from 1992 to 2010, 144 SCA-patients (84M, 60F) have now been transplanted with a geno-identical donor using BU-CY-ATG as CR at the median age of 9.0 years (range:3.2-27.5). Transplants were performed in 16 different centers but 60 were performed in Hopital St-Louis and 21 in Hopital Debré in Paris. All recipients were SS or Sb0 and 76% of them were CMV+. All had been transfused and 47% had received more than 20 units. The source of cells was the bone marrow (BM) (n=121), cord blood (CB) alone (n=21), CSP (n=1) or BM+CB (n=1). GvHD prophylaxis consisted of the association of cyclosporine (CSA)-short MTX for BMT and CSA alone for CBT. Results: Engraftment was successful in 141/144; the time to absolute neutrophil count > 500/mm3 was significantly shorter after BMT compared to CBT (mean ± SD; 21.3 ± 6.7 vs 32.1 ± 9.8, respectively; p Conclusion: These results with 121 patients transplanted since 2000 confirm that it is possible to offer more than 95% chances of cure to SCA-children, indicating that HLA-geno-identical HSCT after myeloablative conditioning with ATG should be considered as standard of care for SCA children, not only for those at high risk of stroke but also for children experiencing crises or other complications requiring intensive therapy such as transfusion program or hydroxyurea. Sibling cord-blood cryopreservation should be systematically offered and pre-implantation genetic diagnosis coupled with HLA selection discussed with the parents. Disclosures: No relevant conflicts of interest to declare.

From 06/93 to 12/99, 1395 children and adolescents were included in the FRALLE 93 protocol: group A (Very Low Risk): 182, B (Standard risk): 672 and C (High risk including T-ALL): 541. The median FU is 9.5 yr. Inclusion criterias in group B were: age between 1 and 15 yr, WBC< 100,000, BCP phenotype and no poor-prognosis cytogenetic feature (MLL rearrangement or Ph1). Group B pts were randomised in a 2-steps schedule: at inclusion: daunorubicin (DNR: 40 mg/m2 × 2) vs idarubicin (IDA: 8 mg/m2 × 2), and at consolidation: high-dose IV methotrexate (HD-MTX): 4 × 8g/m2 at D1, D15, D29 and D42, vs low-dose po MTX (LD-MTX): 4 × 25 mg/m2; the number of triple IT was the same for both arms (N = 18). Pts with CNS leukemia were not randomized for MTX. During induction, pts were also classified on D21 bone marrow aspiration according to the level of residual blasts: M1 (< 5%): n=555, M2 (6–25%): n=71 and M3 (> 25%): n=41; M2/M3 pts received 1 more antracyclin infusion at D22 and M3 pts were subsequently treated according to the HR group and not randomized for MTX. Both M1 and M2 pts who reached CR were randomized for MTX. The overall group B EFS, DFS and OS were respectively 80±2, 81±2, and 91±1%. Globally there is no statistically significant impact of 1st or 2nd randomization on the outcome of patients. When we look at the outcome according to the D21 status, the EFS are very different: M1: 84±2%, M2: 63±6% and M3: 74±7%. The very poor EFS of M2 pts, who can not actually be classified as SR pts, and the fact that M1 pts represent 90% of pts randomized for MTX led us to analyse separately M1 pts. For M1 pts there is no interaction between 1st and 2nd randomization for survival, EFS and relapse rate (Gail and Simon test, p = 0.51); therefore pts were pooled for 2nd randomization analysis. Among M1 pts, 271 pts were randomized for HD-MTX and 264 for LD-MTX; there is no difference regarding age or leucocytosis between the 2 arms. Results are as follows: 5-yr EFS Relapses CI iBM relapses CI Other relapses CI 5-yr OS (EFS: event-free survival, CI: cumulative incidence, iBM: isolated bone-marrow, OS: overall survival) HD-MTX 87.82±1.99% 0.12±0.04 7.01±0.02 5.17±0.02 95.20±1.30 LD-MTX 79.92±2.47% 0.20±0.06 10.6±0.03 9.10±0.03 88.64±1.95 Test log-rank Gray Gray Gray log-rank p value 0.028 0.037 0.16 0.18 0.07 At the contrary, among M2 pts there is no difference in EFS for pts treated with HD-MTX (61±7%) and LD-MTX (65±9%) Conclusion: HD-MTX seems to benefit to pts with standard-risk BCP-ALL and good early response to chemotherapy, and the benefit is associated with a reduction in the number of relapses. No benefit is demonstrated in M2 pts with SER who have a very poor outcome and do require a more intensive treatment; the better EFS of M3 patients treated with double delayed intensification is in favour of this hypothesis.

Adolescence has been claimed since the seventies to be associated to a a bad prognosis in childhood ALL. Out of 4658 patients with ALL, 258 adolescents (15–20 year old)(5.5%) were treated in the successive FRALLE 83, FRALLE 87–89, FRALLE 92 (pilot phase), FRALLE 93 and FRALLE 2000 protocols. The main characteristics were: a sex ratio of 1.8 (M/F), a B-lineage in 71% of the cases vs T lineage in 29%, and a median WBC of 12 G/L (9–1000). Translocation and fusion transcripts were searched for in 120 evaluable BCP-ALL: t(9;22)/BCR-ABL, 8 pts (6%); t(1;19)/E2A-PBX1, 12 pts (10%); t(4;11)/MLL-AF4, 4 pts (3%). Out of 75 evaluable pts t(12;21)/TEL-AML1 was found in only 4 pts (3%). 242 out of 258 adolescents were in CR at the end of induction therapy(EOI)(94%) without any significant difference according to the era. Nevertheless a major difference in the 3y and 5y EFS was found: Number of pts CR at EOI (%) 3y EFS (%) 5y EFS (%) 10y EFS (%) *: p=.04; **: p=.04 Eighties (F83, F87–89) 100 93 42 +/− 5 35 +/− 5 35 +/− 5 Nineties (F92, F93) 84 93 71 +/−5* 67 +/− 5** 67 +/− 5 2000– (F2000) 74 96 86 +/−5* 86 +/− 10** NYA The main modification introduced in the nineties was the adoption of a double delayed intensification for the good early responders. Autologous BMT or allogenic BMT were indicated in bad early responders (D8 poor prednisone response, D21 marrow M3 response) and/or unfavourable cytogenetics. The better results of the 2000 protocol can mainly be explained by the further intensification of chemotherapy between induction and delayed Intensification 1 and before delayed Intensification 2. These better results were obtained despite decreasing the indications of BMT (6 performed vs 20 in the nineties) and of CNS irradiation (100% in the nineties vs 35% in the current era, including the TBI for BMTs). Conclusions:excellent results can now be achieved in adolescents with ALLthis study emphasizes again the need to treat adolescents with ALL according to pediatric intensive protocols and not “adult-type” protocols, as we recently suggested (Boissel et al, J Clin Oncol 2003).Whether this could also be applied to young adults remains to be demonstrated but seems appealing.

The particular technical challenges of apheresis in children require the highest quality of stem cell mobilisation. To date, G-CSF remains the reference. The arrival of pegfilgrastim (pegf) theoretically allows the maintenance of an elevated and constant serum level of G-CSF after only one injection. DESIGN: eleven children (2–16 yrs) undergoing chemotherapy for malignancy were consecutively included in a prospective pilot study. Mobilization consisted of one sc injection of 300 μg/kg pegf in haematological steady state. Apheresis was begun once the value of 20 CD34+/μl cells was reached in the blood, or at day 4 after pegf administration. RESULTS: at first apheresis the mean CD34+ cell, mononuclear cell and polynuclear blood counts were respectively 98/μl (12–353), 7.26×109/l (1.0–9.5) and 39.3×109/l (4.6–57.3). The CD34+cell peak level was obtained on day 3 after injection (3–5). The first standard apheresis (less than 3 patient blood volumes) allowed the harvest of more than 5×106 CD34+ cells in 9/11 pts, the median CD34+ cell harvest being 13.5×106/kg (range 1.6–36). On day six after injection, the median ANC was 13.6×109/l. These results were compared to 3 historical prospective cohorts of children who received non-conjugated G-CSF at 10, 20 or 2×12 μg/kg/j, respectively. The four cohorts were not different for age, weight, diagnosis and rounds of chemotherapy. Mobilisation with pegf was more efficient than with G-CSF at 10 μg/kg/d (p Figure Figure Tolerance: 8 pts had an elevation of LDH, 3 a hyperuricemia respectively up to 2 times and 1.5 times the upper limit. After reinfusion, polynuclear recovery (ANC>500/μl) was obtained after (median) 11.5 days (11–13); platelet recovery (>20 G/l) was reached on median day 17 (12–20). CONCLUSION: the combination of predictable mobilisation kinetics similar to those of non-pegylated G-CSF, a better acceptance profile together with an efficiency which appears to be at least as good, seems to represent progress in stem cell mobilisation in children. However, sustained blood WBC levels indicating that hematopoiesis has not returned to steady state necessitates a slight delay (at least 7 days) in resuming the chemotherapy program.