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Abstract 4978 Introduction: Organ transplantation recipients are generally considered to be at higher risk to develop a malignancy mainly due to prolonged inmunosuppression. The most common haematologic malignancies observed in the post-transplantation setting are B-cell lymphoproliferative disorders. Myeloid neoplasms are rare and most of them have been reported in patients undergoing heart, lung or kidney transplant. Only fifteen acute myeloid leukaemia (AML) and two myelodysplasic syndromes (MDS) cases have been described so far. We report the diagnosis of two MDS in two of the 160 paediatric recipients who underwent liver transplantation (LT) in our center. Patient 1: A 6-year-old child received a liver graft for idiopatic fulminant hepatic failure in December 2006. Inmunosuppressive medication was consisted of Basiliximab induction plus Tacrolimus and prednisone. On the eighth postoperative day a histologically proven rejection grade I occurred, successfully treated with methylprednisolone bolus therapy. Subsequently the patient did well until Abril 2010, when a peripheral blood smear showed 18% blast cells, 31% neutrophils, 46%lymphocytes. The white blood cell count was 4.2 × 1000/μL, the haemoglobin 10.6 g/dL and the platelets 34 × 1000/μL. Bone marrow aspiration showed dysplastic changes in the myelopoietic cells and 12% of blast cells. Myelodysplastic syndrome type refractory anemia with exess blasts (RAEB-2) was diagnosed. The blast cells inmunophenotype was CD34+, CD117+, CD13++, and CD33+. Kariotype analysis revealed a normal 46XX kariotype. Patient 2: In May 2007 a 15-year-old female patient underwent LT for idiopathic acute liver failure. Inmunosuppression consisted of tacrolimus and steroids for the first 3 months. No induction therapy was added. The patient remained in good health with good liver function for 31 months. In a routine follow-up in December 2009 pancytopenia was detected. The white blood cell count was 3.1 × 1000/μL with 31% neutrophils, 66% lymphocytes and 2% monocytes. The haemoglobin was 7.7 g/dL, and platelets were 29 × 1000/μL. Subsequent bone marrow aspiration showed multilineage dysplasia and 15% myeloid blast cells, classified as MDS type RAEB-2. No HLA related donor was found. Two months later the bone marrow showed leukemic infiltration with 38% myeloid blast cells. The inmunophenotype was CD34+, CD117+, CD13+, CD33+, CD133+, and MPO+. Cytogenetic analysis revealed a normal 46XX kariotype. AML with myelodysplasia-related changes was diagnosed. No molecular changes typical of therapy-related MDS were found in any of the cases. Donor and recipient genotypes were identified by real-time PCR to quantify donor chimerism (DC) after LT. In the first case, there was no difference between the donor and recipient genotype and chimerism study could not be done. In the second case DC after LT was not found neither at the moment of the MDS diagnose nor in the next 3 months. Conclusion: MDS/AML has rarely been reported after liver transplantation, and MDS isn't frequently found in the paediatric population. In contrast to previous reports rapid progression to AML was observed in our patients. The present cases support the need for further investigation of the mechanism leading to post-transplant myelodysplastic syndromes and the acute leukaemia in the setting of solid organ transplantation. Disclosures: No relevant conflicts of interest to declare.

Abstract 1811 Poster Board I-837 The prognostic significance of achieving complete remission (CR) in Multiple Myeloma (MM) has finally been accepted. However, available studies have been based on series with a median follow-up around 5 years. This time period is insufficient according to the current life expectation of MM. Aim To establish the real effect of prognosis of the different response categories in a cohort of MM patients treated with autologous stem cell transplantation (ASCT) after long term follow up. Patients and methods Follow-up from diagnosis of 344 MM patients transplanted between 1989 and 1998 has been updated. These patients were previously included in a study aimed at establishing the post-ASCT response significance in MM and to validate the EBMT classification (Br J Haemat 2000;109:438-46). It was possible to update the follow up of 322 patients as at April 2009. At this date 99 patients were alive with a median follow-up form diagnosis of 12.5 years. Response categories and evaluated cases were: i) Complete Response (IF-) (CR), n= 84 ii) near Complete Response (EF-/IF+) (nCR), n= 66 iii) Very good partial response (VGPR) ( Results Significant differences in overall survival (OS) and event free survival (EFS) were found between CR and nCR groups (p 0.01 and 0.0022, respectively); or between CR and VGPR (p 0.0001 and 0.0035); no differences were detected between nRC and VGPR groups (p 0.21 and 0.99) and between these groups and PR group (p 0.1 y p 0.8). OS and EFS of patients with ED o PD were lower than the rest of the groups. Overall survival at 12 years was 43% in CR patients, 21% in nCR, 20% in VGPR, 30% in PR, 8% in SD and 0% in PD groups. Median survival (OS, EFS respectively) of each group was 91 months and 36 m, 26 m and 21 m, 20 m and 15 m, 31 m and 12 m, 8 m and 5 m, and 6 and 1 month. Land-mark study (10 years) found a plateau phase in OS and EFS after 11 years. Twenty two percent of patients are still alive with stable status between 11 and 15.54 years and only two cases had relapsed in the non CR group. In a regression study for OS, response was only one variable with statistical significance (CR P Conclusions In MM achieving CR after ASCT is the most important prognostic factor even after long-term follow-up. Relapse rate is very low in patients with >11 years of follow-up, this could mean a cure for patients in CR. Disclosures No relevant conflicts of interest to declare.