ALBERT

Description: Background: The ability to express the ABH antigens in oral mucosa and saliva is present in about 80% of the general population (hence called secretors) and is regulated by the Sec gene on chromosome 19q13.3, which encodes for the enzyme fut2 (α(1,2)Fucosyltransferase), resulting in the expression of blood types in body fluids, including saliva. The gene encoding for the ABH antigens that determines ABO blood type, is located on chromosome 9q34, and transcribes to the enzyme fut1. While fut1 is mainly expressed in erythroid tissue, fut2is expressed in secretory cells. The aim of the present study was to evaluate the ABO type in saliva and red blood cells of patients undergoing allogeneic SCT from ABO mismatched donors Methods: Secretion status and ABO type in saliva and blood were analyzed in patients with different hematological malignancies undergoing alloSCT from ABO incompatible donors and from healthy donors serving as controls. All study participants signed informed consent. For the determination of ABO type in saliva, following mouth rinse, 5 cc of saliva were collected from each participant into fresh tube and immediately frozen at -800C. Saliva ABH antigens were extracted and enzymes were inactivated. Secretor status and ABO type in patients' saliva were determined by inhibition test. Agglutination of diluted A, B or O typed donor red cells was tested macroscopically in the presence or absent of the extracted ABH antigens pre-incubated with anti-A, anti-B or anti-H, respectively. ABO blood type was routinely determined in patients at least every 2 weeks and time to ABO type conversion was recorded as along with all transplant-related clinical data Results: The study cohort included 30 patients (16 males and 14 females; median age 54.2, 18.8-68.5), who underwent alloSCT between Dec 2009 and Feb 2014 from an ABO incompatible donor and were available for routine follow-up. Median follow-up time from transplant to last ABO determination in saliva was 613 days (153-2789).Donors were matched related in 11, matched unrelated in 16 and mismatched unrelated in 3 cases. All grafts were from mobilized peripheral blood. Transplant from major, minor and bidirectional ABO incompatible donors was present in 9, 16 and 5 recipients, respectively. All patients engrafted. Chimerism analysis at day 30 and 100 post transplant by PCR for STR was 100% in 24/25 and 23/25 of tested patients, respectively. Median days to ABO type conversion were 64 (21-290). Of 30 patients, 26 were found to be secretors (87%).In the secretor group, 29/30(96.6%) retained original blood group in the saliva, while one patient originally typed as AB and transplanted from an A type donor, did not retain his original AB blood type in the saliva. It is not clear whether the lack of B-antigen is attributed to the acute mucosal GvHD or to a true conversion of the ABH antigen expression in the saliva Conclusion: To the best of our knowledge, this is the first report of stable chimerism of the ABO blood groups post ABO-incompatible allogeneic transplantation, such that the majority of recipients (96.6%) retained the recipient ABO group in the saliva, while expressing the donor ABO group in the blood. The significance of these findings and correlation with long-term outcome need to be further studied in larger patient cohort Disclosures No relevant conflicts of interest to declare.

Description: Background: High-dose therapy (HDT) with melphalan 200 mg/m2 (MEL200) followed by autologous hematopoietic cell transplantation (HCT) after an induction therapy is considered the standard of care for patients with newly diagnosed multiple myeloma younger than 65 years. Data are limited for patients above the age of 65 years. We aimed to test the feasibility, efficacy and toxicity of HDT/HCT in patients 〉 65 years. Methods: We included all consecutive patients with multiple myeloma aged 60 and above who underwent an upfront first HCT within 9 months of diagnosis, at 4 Israeli bone marrow transplantation centers. We recorded and compared transplantation-associated toxicity and outcomes between patients 〉65 years (elderly group) and patients 60-65 years (younger group). Results: 220 patients fulfilling the above inclusion criteria underwent HCT between the years 2000 – 2014. Median age of the younger and the elderly group were 62 (range, 60-65) and 68 (range, 66-75), respectively. There were no differences in patient characteristics between the 2 cohorts except of the status of disease at HCT, Table. As expected, higher percentage of patients in the younger group received melphalan 200 mg/m^2 compared to the older group (77% vs. 57%, p=.002). There were no differences in the median day of neutrophil engraftment, the incidence of documented infections, the percentage of patients with grade 3-4 mucositis and the occurrence of cardiovascular events, between the two groups. Within a median follow up of 18 months, 136 patients are alive. There was no difference in non-relapse mortality at 100 days post HCT (4.7%, vs. 5%, p=.9). There was no difference in the percentage of patients with improvement in disease status after HCT, per the IMWG criteria, between the 2 groups in all patients (36%, vs. 35%, p=.87) and among sub-group of patients who failed to reach VGPR pre-transplant (p=.18). At 3 year post HCT progression-free survival was higher in the younger group, compared to patients in the elderly group (42% vs. 29% , p=.04), however this was no longer true after adjustment for disease status prior to HCT (p=.49). In the elderly group, melphalan 200 mg/m^2 compared to lower doses were not associated with improved progression-free survival (p=.69), Figure. Multivariate analysis identified only lambda chain myeloma and no improvement in disease response after HCT to predict a worse progression-free survival (HR 1.7, p=.045 and HR=2.9, p=.021, respectively), while melphalan doses and the age of patients did not predict progression-free survival. There was no difference in overall survival between the younger and the elderly groups (p=.2). Conclusions: Toxicity profile, response rate, progression-free and overall survival of HCT in elderly patients with myeloma is similar to younger patients. Lower melphalan doses given as a preparative regimen do not hamper efficacy of HCT. Randomized controlled trials are needed to confirm the feasibility and outcomes of HCT in patients older than 65 years. Table Patients’, collection and preparative regimen’s characteristics Datum Young group (N=133) Older group (N=87) P value Age (median, range) years 62 (60-65) 68 (66-75) 1 line prior to HCT 76 70 .41 Status prior to auto 〉PR (%) 68 54 .08 Collection at steady state (%) 44 35 .32 Pleriixafor (%) 6 6 1 Total collected cells (median, range) CD34/kg 6.85 (1.9-33.6) 6.25 (2.6-20) .06 MEL 200 (%) 77 57 .002 Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Description: Introduction: Acute graft-versus-host disease (aGVHD) is a major limitation of allogeneic stem cell transplantation (alloSCT) due to associated morbidity and mortality. A search for biomarkers that predict its occurrence is continuously evolving. Regulatory T cells (T regs) have been shown to suppress the early expansion of alloreactive donor T cells and limit the capacity to induce GVHD without minimizing the graft-versus-leukemia (GVL) effect. Recently, the role of regulatory B cells (B reg) in GHVD was demonstrated, with exacerbation of GVHD in both donor and host mice lacking functional regulatory B cells. Semaphorin 3A (Sema3A) is an immunoregulatory molecule secreted by activated B, T and antigen presenting cells. It enhances suppressor ability of B and T regulatory cells by increased secretion of interleukin-10 (IL-10) and transforming growth factor β (TGF-β). The aim of the present study was to explore whether Sema3A expression on B reg and T reg cells from donors and/or recipients pre- or early post-transplantation can predict occurrence of aGVHD. Methods: Thirty four consecutive patients referred to alloSCT were included in the first study cohort. Additionally, 10 donor/recipient (D/R) pairs were enrolled. All participants signed informed consent. 20 cc of fresh peripheral blood were drawn from recipients at day -7 pre-alloSCT and upon WBC engraftment, as well as from their corresponding donors. Mononuclear cells were isolated using ficoll gradient separation and subjected to FACS analysis using monoclonal antibodies evaluating the level of Sema3A expression on B reg cells (CD19/CD25high/ Sema3A), T reg cells (CD4/CD25high/Sema3A) and natural killer (NK) cells (CD3/CD56). Cutoff for positive expression of Sema3A on regulatory cells was considered only if ≥20% of cells expressed the above phenotype of T, B cell and NK population. The FACS results correlated with occurrence of clinical aGVHD grade II-IV. Descriptive statistical analysis and student t test are used to describe results. Results: Overall, 44 recipients were analyzed. Median age at transplant was 49.9 (18-69), 34 were diagnosed with acute leukemia/MDS, 8 - lymphoproliferative and 2 - myeloproliferative diseases. All patients received peripheral mobilized stem cells. Myeloablative conditioning was administered to 33 and reduced intensity to 11 patients. GVHD prophylaxis consisted of standard cyclosporine and methotrexate. Twenty patients developed aGVHD grade II-IV, mostly grade II –III (80%). Recipient expression of Sema3A on B cells pre-transplant was higher in patients without aGVHD versus those with aGVHD (79.9% vs 69.5%, respectively; p