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Flow chart of the study displaying the three cohorts.

Waffle chart (%) of patients addressed for cytopenia exploration after OC exposed to a PARPi treatment from cytopenia diagnosis (A) and cytopenia diagnosis based on NGS results (B). Dot plots (C) showing the median WBC, hemoglobin, and platelet counts from patients referred for cytopenia exploration after OC exposed to a PARPi treatment according to t-MN diagnosis (“t-MN”) or not (“Cytopenia”).

Blood smear and bone marrow aspiration of patient referred for cytopenia post PARPi.

Commutation plot visualizing the mutated genes in t-MN after OC according to PARPi treatment.

Univariate analysis for overall survival from t-MN diagnosis of patients from the national cohort.

TP53 mutations characteristics among t-MN PARPi national cohort.

Purpose:To provide insights into the diagnosis and management of therapy-related myeloid neoplasms (t-MN) following PARP inhibitors (PARPi).Experimental Design:In a French cancer center, we identified and described the profiles of 13 t-MN diagnosed among 37 patients with ovarian cancer referred to hematology consultation for cytopenia under PARPi. Next, we described these 13 t-MN post-PARPi among 37 t-MN post ovarian cancer according to PARPi exposure. Finally, we described 69 t-MN post-PARPi in a national cohort.Results:From 2016 to 2021, cumulative incidence of t-MN was 3.5% (13/373) among patients with ovarian cancer treated with PARPi. At time of hematologic consultation, patients with t-MN had a longer PARPi exposure (9 vs. 3 months, P = 0.01), lower platelet count (74 vs. 173 G/L, P = 0.0005), and more cytopenias (2 vs. 1, P = 0.0005). Compared with t-MN not exposed to PARPi, patients with t-MN-PARPi had more BRCA1/2 germline mutation (61.5% vs. 0%, P = 0.03) but similar overall survival (OS). In the national cohort, most t-MN post-PARPi had a complex karyotype (61%) associated with a high rate of TP53 mutation (71%). Median OS was 9.6 months (interquartile range, 4–14.6). In multivariate analysis, a longer time between end of PARPi and t-MN (HR, 1.046; P = 0.02), olaparib compared with other PARPi (HR, 5.82; P = 0.003) and acute myeloid leukemia (HR, 2.485; P = 0.01) were associated with shorter OS.Conclusions:In a large series, we described a high incidence of t-MN post-PARPi associated with unfavorable cytogenetic and molecular abnormalities leading to poor OS. Early detection is crucial, particularly in cases of delayed cytopenia.

Univariate analysis for overall survival from t-MN diagnosis of patients diagnosed with t-MN after OC according to PARPi exposure.

Purpose: To provide insights into the diagnosis and management of therapy-related myeloid neoplasms (t-MN) following PARP inhibitors (PARPi). Experimental Design: In a French cancer center, we identified and described the profiles of 13 t-MN diagnosed among 37 patients with ovarian cancer referred to hematology consultation for cytopenia under PARPi. Next, we described these 13 t-MN post-PARPi among 37 t-MN post ovarian cancer according to PARPi exposure. Finally, we described 69 t-MN post-PARPi in a national cohort. Results: From 2016 to 2021, cumulative incidence of t-MN was 3.5% (13/373) among patients with ovarian cancer treated with PARPi. At time of hematologic consultation, patients with t-MN had a longer PARPi exposure (9 vs. 3 months, P = 0.01), lower platelet count (74 vs. 173 G/L, P = 0.0005), and more cytopenias (2 vs. 1, P = 0.0005). Compared with t-MN not exposed to PARPi, patients with t-MN-PARPi had more BRCA1/2 germline mutation (61.5% vs. 0%, P = 0.03) but similar overall survival (OS). In the national cohort, most t-MN post-PARPi had a complex karyotype (61%) associated with a high rate of TP53 mutation (71%). Median OS was 9.6 months (interquartile range, 4–14.6). In multivariate analysis, a longer time between end of PARPi and t-MN (HR, 1.046; P = 0.02), olaparib compared with other PARPi (HR, 5.82; P = 0.003) and acute myeloid leukemia (HR, 2.485; P = 0.01) were associated with shorter OS. Conclusions: In a large series, we described a high incidence of t-MN post-PARPi associated with unfavorable cytogenetic and molecular abnormalities leading to poor OS. Early detection is crucial, particularly in cases of delayed cytopenia.

Background Subcutaneous (s.c.) administration of bortezomib is the most widely used route of administration for the treatment of patients with multiple myeloma. No study has as yet prospectively evaluated home versus hospital administration of s.c. bortezomib with respect to patient preference and cost. Patients and methods In this prospective trial, myeloma patients received the first administration of s.c. bortezomib of each cycle in the outpatient unit of the Department of Hematology. When possible, all subsequent doses of bortezomib within each cycle were provided at home. A cost analysis was carried out to compare the average cost of an injection of bortezomib in the outpatient unit and at home. In order to compare hospital and home administration of bortezomib for preference and satisfaction, patients had to complete 2 simple questionnaires analyzing 16 criteria, such as quality of life, well-being, social life, satisfaction, safety, quality of care, the reduction in personal transportation time, and personal anxiety. Each item was analyzed using a Likert scale. Results Fifty patients were studied. Overall, a total of 1043 s.c. injections of bortezomib were carried out, 655 (62.8%) at home, and 388 (35.2%) in the outpatient unit. The cost analysis showed that the total cost of one s.c. injection of bortezomib in the outpatient unit was e1510.09 versus e1224.57 for the home administration, which represents a reduction of e285.52, i.e. 20% of the cost of the hospital administration. The evaluation of patient preference and satisfaction showed that home administration improved the quality of life in 84% of the patients, increased well-being in 78%, and improved the activities of daily living in 72% of the cases. Overall, 98% of the patients noted their preference for home administration over the hospital administration of bortezomib. Conclusion Home administration of s.c. bortezomib is cost-effective and is preferred by myeloma patients compared with hospital administration.

Introduction Next generation sequencing (NGS) has allowed to improve knowledge about the genomic landscape of hematological malignancies. Somatic mutations (SM) are valuable new biomarkers but the utility of incorporating routine sequencing to guide diagnosis and therapeutic decisions remains challenging. We report here an observational multicentric study aimed at assessing the impact of SM testing by NGS in a real-life setting on the diagnosis and treatment of chronic myeloid malignancies (CMM). Patients and Method All patients who benefited from molecular assessment, between 10/2014 and 03/2019 in our University Hospital were included. All provided informed consent for data collection. All NGS requests were validated during a regional multidisciplinary concertation meeting. A custom targeted panel of 34 genes (145kbp i.e. ASXL1,BCOR, BCORL1, CBL, CSF3R, DNMT3A, ETV6, EZH2, GATA2, IDH1, IDH2, JAK2, KDM6A, KIT, KRAS, MPL, NPM1, NRAS, PIGA, PTEN, PTPN11, RAD21, RUNX1, SETBP1, SF3B1, SMC1A, SMC3, SRSF2, STAG2, TET2, TNFAIP3, TP53, U2AF1, ZRSR2) was applied on DNA extracted from peripheral blood or bone marrow samples. DNA libraries, built with the Haloplex® target enrichment protocol (Agilent Technologies, Santa Clara, CA), were paired-end sequenced (150bp reads) with a MiSeq® Instrument (Illumina, San Diego, CA). Data analysis used an in-house pipeline including three variant callings (GATK HaplotypeCaller, VarScan and SAMTools). In a first group (A), NGS indication was to search for clonal hematopoiesis (CH), defined by the presence of at least one SM, in order to confirm or rule out a diagnosis of Idiopathic Cytopenia of Undetermined Significance (ICUS), Clonal Cytopenia of Undetermined Significance (CCUS), myelodysplastic syndrome (MDS), mixed myelodysplastic/myeloproliferative neoplasm (MDS/MPN), aplastic anemia (AA)/hypoplastic myelodysplasia (hMDS) or myeloproliferative neoplasm (MPN), based on recommendations of the WHO classification. In a second group (B), the theranostic impact of SM was studied. Prognostic SMs according to Bejar (2011) were used for MDS and MDS/MPN excluding chronic myelomonocytic leukemia that were analyzed with Itzykson score (2013) and/or CPSS-Mol score (Elena 2016). Prognostic SMs according to Vannucchi (2013) were used for myelofibrosis. Results The median age of the cohort was 60 years old (range: 10-87) with a median follow up of 1.1 years from molecular assessment to last follow-up. Within group A (94 patients), the most frequent blood count anomalies were cytopenia (68%), thrombocytosis (16%), and monocytosis (13%). The karyotype was normal in 77% and failed in 5% of the cases. Non-specific abnormalities (i.e. loss of chr Y, del 20q), were found in 8% of the cases. Before molecular assessment, the diagnoses proposed were ICUS (n=37), suspicion of MDS/MPN (n=16), AA/hMDS (n=16), or MPN (n=25). CH was detected in 31 patients comforting the diagnosis of CMM for 33% of group A (8 CCUS, 3 MDS, 7 MDS/MPN, 6 medullary hypoplasia, 7 MPN) patients. Considering the patients for whom no CH was detected (n=63), the initial suspected diagnosis of CMM was ruled out in 47 patients (i.e. 50% of group A). For the 16 remaining (i.e. 17% of group A), no firm diagnosis could be retained. Within group B (95 patients), NGS identified prognosis SM in 33% of the patients, i.e. poor prognosis SM in 24, including 8/40 MDS, 10/29 MDS/MPN and 6/17 myelofibrosis and good prognosis SM(SF3B1) in 7 of them, respectively 6/40 MDS and 1/29 MDS/MPN. Prognostic SMs had a therapeutic impact in 18/95 pts (19%). Indeed 13 patients with poor prognosis SM had a therapeutic change including 12 allogeneic stem-cell transplantation and 1 hypomethylating agent. Conversely, 5 patients with a good prognosis SM or absence of poor prognosis SM had a de-escalation of treatment intensity. Conclusion The use of NGS in daily practice had a clinical impact in both diagnostic and therapeutic decisions provided that the prescription is made in a critically explored context and not as a systematic test. In this "real life" cohort, the presence or absence of SM was a useful complement for integrated diagnoses in 83% of the patients, allowing to confirm (33%), or exclude (50%) a suspected condition. Moreover, in this cohort 34% of the patients had a SM with a reported prognostic impact and the treatment was modified in 19% of the cases. Yet, it remains necessary to integrate these results with other diagnostic criteria. Disclosures Peterlin: AbbVie Inc: Consultancy; Jazz Pharma: Consultancy; Astellas: Consultancy; Daiichi-Sankyo: Consultancy. Moreau:Janssen: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Amgen: Consultancy, Honoraria. Le Gouill:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support; Roche-Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support. Chevallier:Daiichi Sankyo: Honoraria; Incyte: Consultancy, Honoraria; Jazz Pharmaceuticals: Honoraria.

Recent advances in allogeneic stem cell transplantation (allo-HSCT) have included the advent of reduced-intensity conditioning (RIC) regimens to decrease the toxicity of myeloablative allo-SCT and the use of double umbilical cord blood (dUCB) units as a graft source in adults lacking a suitable donor. The FB2A2 regimen (fludarabine 30 mg/kg/day for 5-6 days + i.v. busulfan 3.6 mg/kg/day for 2 days + rabbit antithymocyte globulin 2.5 mg/kg/day for 2 days) supported by peripheral blood stem cells (PBSCs) and the TCF regimen (fludarabine 200 mg/m² for 5 days + cyclophosphamide 50 mg/kg for 1 day + low-dose [2 Gy] total body irradiation) supported by dUCB units are currently the most widely used RIC regimens in many centers and could be considered standard of care in adults eligible for an RIC allo-SCT. Here we compared, retrospectively, the outcomes of adults patients who received the FB2A2-PBSC RIC regimen (n = 52; median age, 59 years; median follow-up, 19 months) and those who received the dUCB-TCF RIC regimen (n = 39; median age, 56 years; median follow-up, 20 months) for allo-SCT between January 2007 and November 2010. There were no significant between-group differences in patient and disease characteristics. Cumulative incidences of engraftment, acute grade II-IV and chronic graft-versus-host disease were similar in the 2 groups. The median time to platelet recovery, incidence of early death (before day +100), and 2-year nonrelapse mortality were significantly higher in the dUCB-TCF group (38 days versus 0 days [P

Few data are available on the efficacy of the combination of lenalidomide plus dexamethasone (Len/Dex) in very elderly patients above 75 years of age with relapsed multiple myeloma (MM). We report here a single-center series of 45 consecutive patients aged 75 years or older with relapsed MM treated with this combination. The overall response rate was 62% and the median progression-free survival was 14 months, which compares favorably to that described in the two pivotal prospective studies that formed the basis for the approval of Len/Dex in the relapse setting. Our study confirms that Len/Dex is an effective combination in very elderly patients with relapsed MM.

This study addressed the question of upfront allo-SCT in untreated PTCL patients (n = 49). The 2-year OS rate was 59% but 72.5% for transplanted patients (n = 29). Disease status at the time of transplantation was predictive marker for PFS/OS. This work shows that upfront allo-SCT is feasible with low TRM and provide long-term disease control in PTCLs but one-third of patients is chemo-refractory. Background Peripheral T-cell lymphomas (PTCLs) are rare and heterogeneous diseases with dismal outcome when treated with chemotherapy alone. Because allogeneic stem-cell transplantation (allo-SCT) can cure relapse/refractory patients, we hypothesized that upfront allo-SCT may provide a better outcome. Therefore, all patients that presented with advanced PTCL in our institution at diagnosis were scheduled to undergo upfront allo-SCT after induction chemotherapy. Patients and methods The aim of the present work was to assess the feasibility and toxicity of upfront allo-SCT. From 2004 to 2012, 49 newly diagnosed PTCL patients were scheduled to receive upfront allo-SCT. A human leukocyte antigen-matched donor was found for 42 patients: related to the patient in 15 cases, unrelated in 20 cases, and suitable cord blood units were used in 7 cases. Results After induction chemotherapy, 17 patients reached complete remission and 29 (60%) proceeded to upfront allo-SCT. For all patients, the 1 and 2-year overall survival (OS) rates were 59% [95% confidence interval (CI) 47–75] and 55% (95% CI 43–71), respectively. The most frequent reason we did not proceed to allo-SCT was disease progression or insufficient response after induction. For transplanted patients, the 1- and 2-year OS were 76% (95% CI 62–93) and 72.5% (95% CI 58–91), respectively. Toxicity-related mortality (TRM) 1 year after allo-SCT was only 8.2% (95% CI 0–18.5). The 2-year progression-free survival (PFS) rate of patients who did not proceed to allo-SCT (n = 20) was below 30%. The disease status at the time of transplantation was a strong predictive marker for both PFS and OS in transplant patients. Conclusions Upfront allo-SCT in PTCLs is feasible with low TRM, and it provides long-term disease control. However, one-third of patients remain chemo-refractory and, thus, new therapeutic approaches are warranted. The role of upfront allo-SCT compared with other therapeutic approaches in PTCLs requires investigation in randomized studies.

Patients with hematopoietic malignancies relapsing after allogeneic hematopoietic SCT (allo-HSCT) have a poor prognosis. We retrospectively analyzed the patients who received azacitidine in our center in the course of treatment of their post-transplant relapse. We identified 31 patients. Relapse occurred at a median of 3.7 (1.7-37.6) months following allo-HSCT. Patients received a median number of three cycles (1-12) of azacitidine (7 days, 75 mg/m(2) daily). Thirty-nine percent of patients had either a monosomal karyotype or a complex karyotype. Eleven patients (35%) received at least one DLI. Eleven patients responded to azacitidine, with four patients achieving a CR (13%). Median time to best response was 92 (35-247) days, with a median duration of 209 (64-751) days. One-year estimated survival rate was 14%. In conclusion, azacitidine may reinduce durable remissions in very few patients with AML or myelodysplastic syndrome. The toxicity related to azacitidine was high, although it may be difficult to distinguish between treatment-related side effects, namely due to cytopenia and toxicity due to the relapse or disease progression itself. Early administration of azacitidine after transplant followed by DLI should be considered as a pre-emptive therapy for potential relapse in patients with minimal residual disease or high-risk myeloid malignancies.

Landscape analyses of mutational patterns have shown that virtually all myelodysplastic syndromes (MDS) harbor somatic mutations in >80% of cases. These molecular alterations provide useful clonality markers with a potential for early diagnosis of MDS when only cytopenia without marked dysplasia is observed. These markers have been proposed as future prognostic tools to guide therapeutic strategies (Bejar et al., 2011; Itzykson et al, 2013; Mufti et al 2013). Mutational analysis is finally a good way to track disease complexity by deciphering oligoclonality in MDS and better understand clonal evolution. Alterations in the TP53 gene are the most common cause of tumor escape from apoptosis. The aim of this study was to identify TP53 mutations in consecutive samples of lower-risk MDS (IPSS ≤1) with del(5q)obtained at follow-up or progression after sequential classical treatments. Next-generation sequencing (NGS) was used to backtrack the mutant clone(s) identified in late samples. The study was performed both by conventional Sanger sequencing and NGS on a GS Junior Instrument (Roche Applied Science, Mannheim, Germany). For each sample, eight exons (4-11) were amplified from 320 ng of DNA with preconfigured primer plates provided within the IRON II study network. PCR reactions were performed using the FastStart High Fidelity PCR System kit (Roche Applied Science). After double purification with Agencourt AMPure XP beads (Beckman Coulter, Miami, FL), exon-specific amplicon pools were generated and quantified using the Quant-iT™ Broad-Range PicoGreen DNA Assay Kit (Invitrogen, Carlsbad, CA). Emulsion PCR was performed with GS Junior emPCR Reagents (Lib-A) (Roche Applied Science) using 5 x 106 beads at a copy per bead ratio of 0.6. Finally, a fraction of 5-7% enriched beads was loaded on GS Junior Titanium sequencing PicoTiterPlate kit (Roche Applied Science). Data were analyzed for sequence alignment and variant detection using the GS Junior Sequencer and GS Amplicon Variant Analyzer softwares, versions 2.7 and 2.9 (Roche Applied Science). The results were further processed using the Sequence Pilot software version 4.0.1 (JSI Medical Systems, Kippenheim, Germany). The sensitivity of variant detection was set to a lower limit of >1% for bidirectional reads. This threshold was chosen according to a recent study investigating the assay's lower limit of detection (Grossmann et al., 2013), thus underlining the strength of NGS to identify subclones at a low frequency, not detectable by conventional Sanger analysis. A total of 89 DNA samples were extracted from the cytogenetics pellets of a cohort of 40 MDS with del(5q). TP53 mutation analysis was performed on 40 initial and 49 follow-up or progression samples including serial samples for 23 subjects. The depth of coverage was at least 500X and up to 8,444X per amplicon. Of those samples obtained and analysed at time of last follow-up or progression, 14 (61%) had TP53 mutations, mostly in the DNA-binding domain. Performing backtracking on previously collected serial samples, TP53 mutations were retrieved by NGS in 43% of initial samples (n=6), which is different from what was previously described by Jädersten et al (2011). A complete scenario of clonal evolution was retrieved in 11 cases, evidenced by TP53 mutations and/or cytogenetics. These were always consecutive to treatment with lenalidomide, yet 6 of the 12 cases without clonal evolution were also consecutive lenalidomide. Figure 1 provides the example of a complete follow-up including nine time points. More correlation with treatment will be provided. Although lenalidomide remains the treatment of choice for MDS with del(5q), resistant subclones may survive and culminate even following therapy initiation. This theory was recently suggested by Landau et al. in CLL (2013) and our test results support this. Early detection of emerging subclones could lead to initiation of alternative treatment, and we thus propose that a monitoring of TP53 alleles is performed annually after the onset of therapy for MDS using NGS. Figure 1. Figure 1. Disclosures: Kohlmann: MLL Munich Leukemia Laboratory: Employment. Moreau:CELGENE: Honoraria, Speakers Bureau; JANSSEN: Honoraria, Speakers Bureau.

Abstract 956 Background. Unrelated umbilical cord blood cells (UCB) have emerged as an alternative stem cell source for allo-SCT in patients who lack a matched-related or unrelated donor (MUD). Several studies found a similar outcome between HLA 4–6/6 matched UCB and HLA 8/8 matched and 7/8 mismatched unrelated donors, mainly in the setting of standard myeloablative conditioning. However, currently it is more common practice in many centres to search for 10/10 or 9/10 MUD or for double UCB. Thus far, no study focussed on the comparison of outcome of patients who received double UCB allo-SCT versus allo-SCT using 9/10 mismatched donors. With this background, this retrospective analysis assessed outcome after allo-SCT using double UCB cells or 9/10 mismatched donors in the setting of a RIC regimen. Patients and Methods. This analysis was performed in a series of 152 consecutive adult patients treated for hematological malignancies in 2 centers adopting similar transplant procedures. 85 patients were males (56%) and the median age at time of allo-SCT was 53 years (range, 16–69). Diagnoses included 59 AML (39%), 21 MDS/MPN (14%), 42 NHL (28%), 5 Hodgkin diseases (3%), 18 ALL (12%) and 7 Myelomas (5%). 35 patients (23%) had standard risk disease and 117 patients (77%) presented with high risk disease. Conditioning regimen consisted of fludarabine, cyclophosphamide and low dose TBI for 108 patients (71%), fludarabine and busulfan for 35 patients (23%); and other regimens in the remaining 9 patients (6%). 50 patients (33%) received antithymocyte globulin. The donor was double UCB in 110 cases (“dUCB” group) and 9/10 mismatched unrelated in 42 cases (“9/10” group). During the study period, both participating centers adopted the same strategy for donor search and choice: in the absence of matched-related siblings or 10/10 MUD, 9/10 donors were searched. UCB cells were used if no 9/10 donor could be identified within a reasonable time frame (usually 2–3 months after search initiation). Results. With a median follow-up of 30.3 months (range, 6–72.4), the Kaplan-Meier estimate of overall survival (OS) at 2 years was comparable between both groups [52% (95%CI, 42–61%) in the dUCB group versus 48% (95%CI, 32–62%) in the 9/10 group, P=0.55]. The cumulative incidence of NRM was 26% in the dUCB group versus 24% in the 9/10 group (P=0.95). Grade 3–4 acute GVHD and extensive chronic GVHD incidences were 20% versus 21.4% (P=0.83), and 6% versus 21% (P=0.02), in the dUCB group versus the 9/10 group, respectively. The cumulative incidence of relapse was 34% in the dUCB group versus 38% in the 9/10 group (P=0.63). Finally, the estimate of progression-free survival (PFS) at 2 years was 43% (95%CI, 34–52%) in the dUCB group versus 38% (95%CI, 23–53%) in the 9/10 group (P=0.55). In multivariable analysis including the most important parameters associated with outcome (patient's age at transplantation, patient's sex, diagnosis, disease status at transplantation, use of ATG, GVHD prophylaxis), the stem cell source (dUCB versus 9/10) did not have any significant impact on OS (HR=0.92 (95% CI, 0.41–2.08); P=0.86) Conclusion. These data suggest that dUCB is likely a valid alternative graft source compared to 9/10 mismatched unrelated donors in the setting of RIC allo-SCT since both donor types showed similar results in terms of OS, PFS, disease relapse, and acute GVHD incidence. However, the significantly lower incidence of extensive chronic GVHD in the dUCB group is an important and major finding, highlighting the need for a prospective randomized study in this field. Disclosures: No relevant conflicts of interest to declare.

Abstract 3108 Introduction: RIC regimens are increasingly used for allo-SCT in older patients or patients with co-morbidities. The FB2 regimen (Fludarabine 120–150 mg/m2 + I.V. Busulfan 6.4 mg/Kg + ATG 5 mg/Kg) using PBSC as stem cell source is currently the most widely used RIC regimen in many European centres. On the other hand, in patients without a suitable HLA-matched donor, the use of umbilical cord blood stem cells for allo-SCT (uCBT) is increasingly considered, especially using the RIC regimen developed by the Minneapolis group. Series comparing PBSC vs CB as stem cells source for RIC allo-SCT are still scarce and using various RIC regimens before allo-SCT. Patients and Methods: This retrospective single centre analysis compared two homogeneously treated cohorts of patients who had received between January 2007 and November 2010 in our department either a FB2/PBSC allo-SCT (n=52, males: 61%; median age: 59 years (range: 22–70)) or a FC-TBI/uCBT (Fludarabine 200 mg/m2 + Cyclophosphamide 50 mg/Kg + TBI 2 Grays regimen; n=39, males 49%; median age 56 years (range: 22–70). Except for age (p=0.03), there were no significant differences between the 2 groups regarding patients and diseases characteristics: gender (p=0.22), interval between diagnosis and transplant (PBSC: 9 months vs CB: 10 months, p=0.85), disease type (PBSC: myeloid disease 63% vs CB: 67%, p=0.75), status at transplant (complete remission PBSC: 77% vs CB: 67%, p=0.28), prior auto-SCT (PBSC: 35% vs CB: 33%, p=0.90). Donors in the PBSC group were as follows: sibling donors, n=30; HLA-MUD n=20, mismatched unrelated n=2. All patients from the CB group received 2 CB units (HLA matching 4/6 n=25; 5/6 n=53). As for GVHD prophylaxis, patients received cyclosporine (CsA) alone in case of an HLA-identical sibling donor, and CsA+ mycophenolate mofetyl in all other cases. None of the patients from the PBSC group received G-CSF after transplant, while it was administered to all CB recipients. Results: Median follow-up was respectively 19 and 20 months for the PBSC and the CB groups (p=NS). Engraftment and median time for neutrophils recovery were similar between the 2 groups: PBSC: 96% vs CB: 90%, p=0.22; and 17 days (range: 0–39) vs 16 days (range: 8–60), p=0.88, respectively. The median time for platelets recovery (>20000/mm3) was significantly higher in the CB group: 38 days (range: 13–150) vs PBSC: 0 days (range: 0–186) (p Conclusion: Our study suggests that RIC uCBT is a valid alternative in patients lacking an HLA-matched related or unrelated donor and candidate for RIC allo-SCT. Prospective and randomized studies are warranted in order to establish the definitive role of uCBT, especially in patients with acute leukemia, where CB cells may offer a rapidly available source of stem cells in diseases with high tumor kinetics. Disclosures: No relevant conflicts of interest to declare.

Abstract 4483 Introduction: RIC regimens are increasingly used prior to allo-SCT. The FB2 regimen (Fludarabine 120–150 mg/m2 + IV Busulfan 6.4 mg/Kg + ATG Thymoglobuline 5mg/Kg) is currently the most widely used RIC regimen in many European centres. This retrospective analysis aimed to assess the hematopoietic and immune recovery in a homogeneously treated cohort of 53 patients (males: n=33; median age: 59 years (range: 22–70)) who received the FB2 regimen between January 2007 and October 2010 in our department. Patients and Methods: Diagnoses were as follow: AML n=23; ALL n=1; biphenotypic leukemia n=1; lymphoma n=16; myelodysplastic syndrome n=9; multiple myeloma n=3. Nineteen patients (36%) had received a prior autologous SCT. The majority of patients (n=40, 75.5%) were transplanted in complete remission. Thirty patients received a graft from a matched sibling donor (56.5%). All patients, but one (who received unmanipulated bone marrow) received G-CSF-mobilized PBSCs. GVHD prophylaxis consisted of cyclosporine (CsA) alone in patients transplanted with an HLA-identical sibling, and CsA+ mycophenolate mofetyl in other cases. None of the patients received G-CSF during aplasia following transplant while nine patients received erythropoietin before day+100. Results: Engraftment was achieved in 96% of patients (n=51). Median times for neutrophils (n=51) and platelets (n=22) recovery were 17 days (range: 0–39) and 10 days (range: 4–186), respectively. The majority of patients (n=31, 58%) did not receive platelet support during aplasia. The cumulative incidences of grade II-IV and grade III-IV acute GVHD were 30% and 15%, respectively, while overall incidence of chronic extensive GVHD was 33%. With a median follow-up of 19 months (range: 2–53), the 2-year OS, DFS, relapse incidence, and NRM were 63%, 59.5%, 35% and 6%, respectively. In univariate analysis, when regarding pre-transplant factors associated with outcome, the only factor correlated with a significantly higher 2-year OS and DFS was a higher total circulating lymphocytes count at transplant (> 730/mm3) (OS: 81.5% vs 43.2%, p=0.01; DFS: 73.2% vs 45.5%, p=0.03). Regarding post-transplant factors, we found that higher recovery of leukocytes (>5000/mm3) (2-year OS: 78% vs 46%, p=0.007; 2-year DFS: 70% vs 48%, p=0.08), neutrophils (>3230/mm3) (2-year OS: 76% vs 50%, p=0.02; 2-year DFS: 67.5% vs 52.0%, p=0.09), and monocytes (>590/mm3) (2-year OS: 80% vs 47%, p=0.004; 2-year DFS: 75% vs 42%, p=0.007) at day+30 post-transplant were the most significant factors associated with outcome. In multivariate analysis, the only independent factors associated with a significantly higher OS and DFS were a better immune status at transplant (lymphocytes count >730/mm3; HR 0.22; 95%CI: 0.08–0.63, p=0.005; and HR: 0.29; 95%CI: 0.12–0.71, p=0.006, respectively) and a higher monocytes count at day+30 post-transplant (>590/mm3) (HR: 0.24; 95%CI: 0.08–0.66, p=0.006; and HR: 0.28; 95%CI: 0.11– 0.68, p=0.005; respectively). Conclusion: These results suggest that hematopoietic status and recovery before and after FB2 RIC allo-SCT can be significant predictors of outcome. This paves the way for future studies aiming to closely monitor the kinetics of immune recovery after RIC allo-SCT and to evaluate the impact of growth factors and other immunostimulatory cytokines in the setting of RIC allo-SCT. Disclosures: No relevant conflicts of interest to declare.