Winters, Jeffrey L.

Abstract Abstract 4228 Background Peripheral blood stem cells (PBSC) are the preferred graft type for autologous stem cell transplantation (ASCT) and mobilization is typically done using growth factor (GF) alone or a combination of chemotherapy (CTX) and GF. The success of mobilization is influenced by several factors such as prior therapy, mobilization strategy, underlying disease, among others. Patients (Pts) failing to mobilize successfully often have GF dose increased and if unsuccessful, mobilization is reattempted with chemotherapy + GF or G-CSF (Granulocyte Colony-Stimulating factor) + GM-CSF (Granulocyte–Macrophage Colony-Stimulating factor). More recently, plerixafor, a CXCR4 inhibitor, has been found to enhance G-CSF based collection allowing potential early intervention in poor mobilizers. However, this approach requires valid cut-points for peripheral CD34 counts (pCD34) for cost efficient use. Methods We studied 656 first time, G-CSF based PBSC mobilizers with Non-Hodgkin Lymphoma (562; 86%), or Hodgkin's Disease (94; 14%). Salvage attempts were excluded, as were first attempts using CTX+GCSF, plerixafor or GF combinations. Sensitivity-specificity analysis (Receiver operating characteristic) was used to define ideal cut-points for predefined outcomes. We used a CD34 yield of 2 million/kg as the minimum required collection and 5 million/kg as the ideal collection for the current analysis. Our current practice is to initiate collection at a pCD34 of 10/uL. Results We first determined the best day 1 pCD34 cutoff for being able to collect at least 2 million/kg PBSC to be 9/uL. Among those with ≥9/uL, only 6.6 % failed to collect at least 2 million compared to 55% among the rest (P < 0.001). These numbers were 6.3% and 50% respectively using the traditional cutoff of 10/uL. We then examined how the pCD34 on day 2 predicted collection, among those failing to reach the current threshold of 10/uL. Among this group, a pCD34 on day 2 of 9.1/uL was the best cutoff to predict a collection of 2 million/kg. Among those with >=9.1/uL, only 22% failed to collect at least 2 million compared to 79% among the rest (P < 0.001). Among those with day 1 pCD34 < 10, 49% achieved a count of 9.1/uL on day 2. We then examined what pCD34 on day 1 can best predict a pCD34 ≥ 9.1 on day 2 and found this to be 5.2/uL. Among those with day 1 pCD34 ≥ 5.2/uL, 79% reached day 2 pCD34 ≥ 9.1 compared to 24% among the rest (P < 0.001). We then determined cutoffs based on ideal targets using only those patients achieving pCD34 count > 10/uL by day 2, since these patients would have started collection without any change in the mobilization technique. We used a maximum of 5 collections to achieve the goal as being ideal, taking into account the most commonly used practice of collecting during weekdays. We examined cutoffs for a target of 5 million/kg for one transplant. The best day 1 or day 2 pCD34 predicting a 5 million/kg yield in 5 collections was 17/uL. Among those with day 1or 2 pCD34 ≥ 17/uL, 4% failed to reach 5 million in ≤ 5 days compared to 96% among the rest (P < 0.001). Conclusions This study provides an estimate of optimal pCD34 count thresholds for early identification of patients with lymphoma at high risk of collection failure. It is reasonable to use the first or second day pCD34 count, since a substantial proportion of patients will achieve the threshold value by day 2 and these patients appear to have similar outcome as those reaching the threshold by day 1. Based on the results here, interventions such as addition of plerixafor can be considered if pCD34 count is < 6/uL on day 1 or < 10/uL by day 2, to achieve the minimum collection of 2 million/kg. However, in order to achieve the ideal targets, a higher threshold should be considered and the recommendation based on the current study would be 17/uL for a target of 5 million. Such a target-adapted strategy may be more appropriate. Disclosures: Kumar: Celgene,Genzyme,Millenium,Novartis,Bayer,: Honoraria, Research Funding. Gertz:Genzyme: Research Funding. Micallef:Genzyme: Research Funding.

Abstract Peripheral blood infused total autograft absolute lymphocyte count (A-ALC) correlates with day 15 absolute lymphocyte count and is an independent prognostic factor for survival after autologous stem cell transplantation (ASCT) for non-Hodgkin lymphoma (NHL). Factors to enhance A-ALC collections are not well defined. We hypothesize that the number of peripheral blood apheresis collections (PBAC) directly correlates with A-ALC. 190 consecutive NHL patients who underwent ASCT at the Mayo Clinic between 1993 and 2001 were analyzed. The primary end point of the study was to assess the correlation between the number of PBAC and A-ALC. The secondary end point was to determine if the number of PBAC affected survival post-ASCT. Of the 190 patients, 18 patients underwent 1 PBAC, 23 patients 2 PBAC, 50 patients 3 PBAC, 37 patients 4 PBAC, 50 patients 5 PBAC, and 12 patients had ≥ 6 PBAC. There was no association between the number of PBAC and the number of CD34+ stem cells collected (p= 0.25). A strong association between number of PBAC and A-ALC (Kruskall Wallis test, p <0.0001)(Figure 1) was identified. Using a cut-off of 4 PBAC, superior overall survival (OS) and progression-free survival (PFS) were observed for patients that underwent 4 PBAC or more compared to patients that underwent less than 4 PBAC (86 months vs 18 months, p <0.0001; 76 months vs 10 months, p <0.0001, respectively). Multivariate analysis demonstrated PBAC ≥ 4 is an independent prognostic factor for OS (RR = 0.654, 95%CI: 0.529–0.804, p< 0.0001) and for PFS (RR = 0.682, 95%CI: 0.561–0.826, p< 0.0001) when compared with other significant factors including performance status, lactate dehydrogenase and extra nodal disease. These data suggest that increasing the number of PBAC beyond the minimum number required to meet CD34+ collection targets may result in improved overall and progression-free survival mediated by an increase in autograft absolute lymphocyte count.

Abstract A device that would provide a rapid evaluation of hemostasis would greatly aid physicians in making scientific decisions regarding transfusion therapy; especially with perioperative bleeding. We performed a prospective in-vitro study with reconstituted, recalcified whole blood (n = 6) separated into samples containing specific deficiencies in platelets, plasma, lyophilized platelets and lyophilized plasma such that the concentrations of the specific platelet or plasma were 0%, 10%, 30%, 50%, and 100%. The whole blood was obtained from consenting healthy volunteers. Samples from the various concentrations of the reconstituted blood were subjected to the following point of care coagulation tests: activated clotting time (ACT), thromboelastogram (TEG), laboratory prothrombin time (PT), laboratory activated partial thromboplastin time (APTT) and Signature+ PT. ACT’s were performed for each of four celite doses (1.5 mg, 3.0 mg, 6.0 mg and 12 mg celite). The four dose celite ACT’s were performed in duplicate and the mean recorded. The TEG was performed in duplicate, and the mean was recorded. The signature+ PT was performed in duplicate, and the mean recorded. The laboratory PT, aPTT, Platelet Count and Fibrinogen were performed once each. ACT values were analyzed within each of the three preparations using analysis of variance. This assessed the strength of the relationship between blood constituent concentration and ACT, and determined whether this relationship differed across varying amounts of celite. Other coagulation parameters including TEG (mA), PT and APTT were analyzed using analysis of variance with a single term for blood constituent concentration. This model determined the strength of the relationship between these coagulation parameters and blood constituent concentration. In addition, the kaolin activated TEG and the signature+ PT was evaluated to determine the strength of the relationship between these tests and the variations in platelet and plasma concentrations. There was a significant correlation between the plasma, platelets and lyophilized plasma concentrations and ACT results (all p < 0.001). There was a significant correlation between plasma platelets and lyophilized plasma and the TEG MA and angle (all p < 0.028). There was a significant correlation between laboratory PT and APTT and plasma, platelets, and lyophilized plasma, lyophilized platelets (all p < 0.001). There was a significant correlation between the Signature+ PT and plasma, lyophilized platelets, and lypholized plasma and platelets (all p < 0.005), (figure 1). A better point of care coagulation device that is based on in-vitro additions of various therapies, and comparison of their effects on coagulation tests may provide better treatment of the bleeding patient. The Signature+ PT could provide the endpoint for such a device whereas the ACT was nonspecific and had a small change in results with large changes in plasma concentration. The additional benefit of lypholized plasma to behave similarly to human plasma may allow such a device to be built. Figure Figure

Abstract Background: The Surveillance, Epidemiology & Risk Factors for TTP (SERF-TTP) study is the largest prospective cohort of idiopathic TTP cases to date. Methods: Patients with first episode of idiopathic TTP were enrolled at 11 sites in the US. Exclusion criteria include solid organ or allogeneic stem cell transplant, anti-neoplastic therapy or malignancy. All patients underwent therapeutic plasma exchange (TPE). Remission is defined as platelet count >150,000/mm3. ADAMTS13 activity was measured by fluorescence resonance energy transfer assay (FRETS-vWF73, Peptides Int.). ADAMTS13 inhibitor was assessed by ELISA (Technozym ADAMTS13 INH ELISA, Technoclone) and functional inhibition of normal ADAMTS13 activity (modified FRETS). Differences between the groups was evaluated by Chi-square test, t-test or Fisher’s exact test. Results: Complete data is available for 57 cases. 84% were female & median age was 42. ADAMTS13 was severely deficient (<10%) in 53%, moderate (10–50%) in 8%, & normal (>50%) in 39%. Adverse events were frequent & most commonly include citrate toxicity and allergic reactions. Long-term followup was available for 56 patients, and overall relapse rate was 25% with median time to relapse of 11 months. The relapse rate was 41% in patients with severe ADAMST13 deficiency & 0% in patients with normal ADAMTS13 activity (p=0.0077). Conclusions: Severe ADAMTS13 deficiency does not define all cases of idiopathic TTP, yet is associated with a unique syndrome characterized by severe thrombocytopenia, normal renal function, presence of ADAMTS13 neutralizing autoantibodies & high risk of relapse. Non-ADAMTS13 deficient idiopathic TTP has clinical features similar to thrombotic microangiopathies associated with stem cell transplant or drugs such as quinine, yet has a better than expected overall survival after TPE. There is likely an alternate disease mechanism for this cohort, possibly immunologic, which may be responsive to TPE and warrants further study. ADAMTS13 < 10% n=30 ADAMTS13 > 50% n=22 p-value * t-test, ** Fisher’s Exact Test, # Chi-Square Test Presenting Labs Hemoglobin (mean) 8.5 9.2 0.22* Platelet count (mean x10^9/L) 19 57 <0.0005* Serum creatinine (mean) 1.33 3.9 0.0012* ADAMTS13 antibody (neutralizing & non-neutralizing) % 100 63.6 0.0004** ADAMTS13 neutralizing antibody % 83 35 .0003# Presenting Symptoms Neurologic symptoms present 45 52.4 0.23# Diarrhea 23 30.4 0.79# Infection 40 43.5 0.79# Past Medical History Connective Tissue Disease % 10 8.5 0.28# Family history of TTP % 0 4.6 0.11# Remission Labs Hemoglobin (mean) 12.2 8.5 0.16* Platelet count (mean x10^9/L)) 169 152 0.15* Serum creatinine (mean) 1.02 3.7 0.0009* Outcomes Therapy-related Adverse events % 71 55 0.24# Time (days) to remission (plt > 150,000) 9.7 9.2 0.89* Early remission (< 8 days) % 73 57 0.20# 30 day Exacerbation rate % 35 28 0.63# 30 day Survival % 96.6 90.0 0.56** Long-term Relapse % 41 0 0.0077**

Abstract Since its emergence as a novel therapy for cutaneous T-cell lymphoma in 1987, extracorporeal photopheresis (ECP) has gained popularity in the fields of solid organ and stem cell transplantation (Perotti et al Transfus Apher Sci 2015). Though ECP is thought to be associated with few adverse effects, we have anecdotally noted that some patients treated with ECP develop iron deficiency anemia. Anemia has been reported in ECP literature at an incidence of anywhere from 0% to 24.5%, however, the etiology of the anemia has not been described (Quaglino et al Int J Dermatol 2013, Flowers et al Blood 2008, Jaksch et al J Heart Lung Transpl 2012, Dignan et al Bone Marrow Transpl 2014). We performed a retrospective chart review to further investigate the magnitude of this potential adverse effect. Adult patients receiving ECP for any indication at Mayo Clinic Hospital-Rochester were eligible for inclusion. Patients with pre-existing iron deficiency anemia (IDA) or physiologic and/or pharmacologic reasons for altered iron homeostasis were excluded from analysis. The primary endpoint was to describe the cumulative incidence of IDA at one year of ECP therapy, utilizing Kaplan-Meier methodology. We defined IDA as a hemoglobin < 12 g/dL (females) or < 14 g/dL (males), plus any of the following: MCV < 80 fL, ferritin < 11 mcg/L, iron < 35 mcg/dL (females) or < 50 mcg/dL (males), total iron binding capacity > 400 mcg/dL, or percent saturation <14%. Secondarily, we aimed to describe the proportion of patients who underwent further diagnostic evaluation of IDA and those that were initiated on iron supplementation for IDA. Patients were followed for the primary endpoint until diagnosis of IDA, death, or date of last ECP session; those who did not develop IDA were censored at the date of last follow-up. Between January 1, 2006 and July 1, 2015, a total of 120 adult patients were treated with ECP at Mayo Clinic in Rochester, MN; 80 patients met inclusion criteria. For the remaining 40 patients, patients were excluded for recent history of transfusions and/or phlebotomy (n=27), incomplete documentation (n=7), IDA at baseline (n=3), or potentially confounding past medical histories (n=3). Treatment of graft-versus-host disease (GVHD) was the foremost ECP indication in our cohort, accounting for 63.8% of our patients. Patients also received ECP for treatment of cutaneous T-cell lymphoma, treatment of solid organ transplant rejection, and other indications (25%, 7.5%, and 3.8%, respectively). Mean age was 55.6 years, 38.7% were female, and the median duration of ECP therapy was 344 days (IQR 130 - 755 days). At 1 year from the start of ECP therapy, the cumulative incidence of IDA in our cohort was 21.1% (95% CI 9% - 31.6%; Figure 1). At 4 years from the start of ECP therapy, the cumulative incidence of IDA was 49.1% (95% CI 26.4% - 64.8%). Of those that developed an IDA at any time during ECP therapy, 6/20 (30%) underwent invasive diagnostic procedures (colonoscopy and/or upper endoscopy) to evaluate the etiology of the IDA. Iron supplementation was initiated in 18/20 (90%) patients; hemoglobin returned to normal in 8 patients (44.4%) based on available follow-up. These data indicate that a substantial number of patients develop IDA while receiving ECP therapy; a finding which may lead to more prompt recognition and treatment of IDA in patients receiving ECP, and perhaps spare expensive diagnostic procedures. Figure 1. Kaplan-Meier Curve of Cumulative Incidence of IDA During ECP Therapy Figure 1. Kaplan-Meier Curve of Cumulative Incidence of IDA During ECP Therapy Disclosures No relevant conflicts of interest to declare.

Abstract Abstract 3231 Poster Board III-168 Background Peripheral blood stem cells (PBSC) are the preferred graft type for autologous stem cell transplantation (ASCT) and mobilization is typically done using growth factor (GF) alone or a combination of chemotherapy (CTX) and GF. The success of mobilization is influenced by several factors such as prior therapy and mobilization strategy. Patients (Pts) failing to mobilize successfully often have GF dose increased and if unsuccessful, mobilization reattempted with chemotherapy + GF or G-CSF (Granulocyte Colony-Stimulating Factor) + GM-CSF (Granulocyte-Macrophage Colony-Stimulating Factor). More recently, plerixafor, a CXCR4 inhibitor, has been found to enhance G-CSF based collection allowing potential early intervention in poor mobilizers. However, this approach requires valid cut-points for peripheral CD34 counts (pCD34) for cost efficient use. Methods We studied 910 first time, G-CSF based PBSC mobilizers with MM (565; 62%), or light chain amyloidosis (345; 38%). Salvage attempts were excluded, as were first attempts using CTX+GCSF, plerixafor or GF combinations. Sensitivity-specificity analysis (ROC) was used to define ideal cut-points for predefined outcomes. We used a CD34 yield of 2 million/kg as the minimum required collection and 4 million/kg as the ideal collection for this analysis. Our current practice is to initiate collection at a pCD34 of 10/uL. Results We first determined the best day 1 pCD34 cutoff for being able to collect at least 2 million/kg PBSC to be 9.2/uL. Among those with ≥9.2/uL, only 1.6% failed to collect at least 2 million compared to 27% among the rest (P < 0.001). These numbers were 1.7% and 25% respectively using the traditional cutoff of 10/uL. We then examined how the pCD34 on day 2 predicted collection, among those failing to reach the current threshold of 10/uL. Among this group, a pCD34 on day 2 of 8/uL was the best cutoff to predict a collection of 2 million/kg. Among those with >8/uL, only 9% failed to collect at least 2 million compared to 48% among the rest (P < 0.001). Among those with day 1 pCD34 < 10, 65% achieved a count of 8/uL on day 2. We then examined what pCD34 on day 1 can best predict a pCD34 ≥ 8 on day 2 and found this to be 5/uL. Among those with day 1 pCD34 ≥ 5/uL, 92% reached day 2 pCD34 ≥ 8 compared to 36% among the rest (P < 0.001).We then determined cutoffs based on ideal targets using only those patients achieving pCD34 count > 10/uL by day 2, since these patients would have started collection without any change in the mobilization technique. We used a maximum of 5 collections to achieve the goal as being ideal, taking into account the most commonly used practice of collecting during weekdays. We examined cutoffs both for a target of 4, 8 and 12 million/kg for one, two or three transplants respectively. Among those with a day 1 or day 2 pCD34 > 10/uL 98% collected 4 million/kg in 5 collections. The best day 1 or day 2 pCD34 predicting a 8 million/kg yield in 5 collections was 21.4/uL and a 12 million/kg yield was 27.9/uL. Among those with day 1or 2 pCD34 ≥ 21.4/uL, 90% collected 8 million compared to 54% among those with pCD34 < 21.4/uL. Similarly, among those with day 1 or 2 pCD34 ≥ 27.9/uL, 79% reached 12 million in ≤ 5 days compared to 17% among those with pCD34 < 27.9/uL (P < 0.001).Finally we examined if poor collection on first day, despite a pCD34 > 10 predicts for poor overall yield. A ratio of day 1 collection (million/kg) to pCD34 day 1 or 2 < 5×104 was highly predictive of failure to get eventual yield of 2 million/kg, with 38% below the cutoff failing to reach the goal compared to 2% for those above the cutoff. Conclusions This study provides an estimate of optimal pCD34 count thresholds for early identification of patients at high risk of collection failure. It is reasonable to use the first or second day pCD34 count, since a substantial proportion of patients will achieve the threshold value by day 2 and have similar outcome as those reaching the threshold by day 1. Based on the results here, interventions such as plerixafor can be considered if pCD34 count is < 5/uL on day 1 or < 9/uL by day 2, to achieve the minimum collection of 2 million/kg. However, in order to achieve the ideal targets, a higher threshold should be considered and the recommendation would be 17/uL, and 28/uL for target of 8 or 12 million respectively. Finally, identification of poor mobilizers after start of collection potentially provides another time point for early intervention, and this needs to be prospectively studied. Disclosures Micallef: Genzyme: Research Funding. Gertz:Genzyme: Research Funding. Kumar:Celgene,Genzyme,Millenium,Novartis,Bayer,: Honoraria, Research Funding.

Abstract Autologous stem cells transplant in tandem is considered the standard therapy for patients with Multiple Myeloma (MM) and Primary Amyloidosis. The collection as well as the infusion of stem cells, which are preserved in dimethyl sulfoxide (DMSO), may cause serious side effects including renal failure. We reviewed the charts of MM patients undergoing stem cell transplant from 2001 through the end of 2005. Patients were grouped into one of 3 categories: Amylodosis, MM with Immunoglobulin G (IgG) and MM with non IgG. Creatinine and creatinine clearance values were collected 14 days prior to, the day of, 3 days post, and 28 days post infusion. The volume of the transplant as well as the number of CD 34+ stem cells reflect the dose of DMSO infused since all the cryopreservation of cells were done with 105 DMSO solution. We also collected data about the administration of nephrotoxic agents such as Aminoglycoside antibiotics, Vancomycin and Amphotercin B because these patients are at increased risk of developing infections. We also reviewed the dose of consolidation chemotherapy (Melphalen) as a potential nephrotoxic agent. Chi-square analysis was used. 645 patients were included [380 (58.82%) males and 265 females (41.18%)]. 384 received Vancomycin, 7 received Gentamycin and 8 received Amphotericin B with total of 146 missing data. 191 (29.57%) had Amyloidosis, 285 (44.12%) IgG MM and 169 (26.32%) non IgG MM. Only 6 transplants were allogeneic. The dose of Melphalen ranged between 0–200 mg/m2 over 2 days at the discretion of the physician. The mean weight was 82.25 Kg and median weight was 81.8 Kg. The mean age 57.12 years and median age was 58 years. 608 patients (94.12%) had one transplant, 35 (5.42%) had 2 transplants and 3 (0.46%) had 3 transplants. The mean volume was 289.20 ml and median volume was 245 ml. The mean number of CD34+ cells was 5.39 × 10(6)/kg with a median of 4.74 × 10(6). The mean and median Creatinine levels were 1.26 mg/dl and 1 mg/dl respectively at 2 weeks prior to transplant, 1.23mg/dl and 1mg/dl on the day of transplant, 1.18 mg/dl and 1mg/dl at 3 days after transplant and finally 1.16mg/dl and 0.9mg/dl at 4 weeks interval. 67 males as well 50 females had renal failure prior to transplant but there was no statistical difference due to gender (p 0.001). Creatinine clearance levels were 83.96 ml/min at 2 weeks prior, 83.84 ml/min at day zero, 88.57 ml/min and 91.89 ml/min respectively. The median were 83.37 ml/min, 82.77 ml/min, 86.43 ml/min and 91.29 ml/min respectively. Even though 35 creatinine values were missing within the first 3 days period, there was no acute renal failure (ARF) (0.5 mg/dl increase) noted with a 95% C.I. 95% in 494 patients with normal creatinine. The creatinine level improved in 93 patients with an abnormal level and only 24 were left with abnormal levels. This might represent a dilutional effect due to fluid administration during the transplant. Concerning the incidence of chronic renal failure (CRF) at 4 weeks interval, considering that only 47 laboratory values were missing the results was as follows: 4 patients had > 0.5 mg/dl creatinine increase from the 485 normal patients with C.I. 95%. CRF was still observed in 38 patients of the 72 patients with baseline renal failure. Even though 9 had very poor creatinine clearance <10ml/min (p 0.01) only 5 were left with severe creatinine clearance after transplant (p 0.05) We found that DMSO does not induce ARF or an exacerbation of CRF in transplants patients for Amyloidosis and Multiple Myeloma.

Abstract Abstract 1178 Poster Board I-200 Background: High-dose chemotherapy with autologous peripheral blood stem cell transplantation (PBSCT) has been shown to be of value in selected patients with malignant lymphoma and multiple myeloma (MM). Both granulocyte macrophage colony stimulating factor (GMCSF) and granulocyte colony stimulating factor (GCSF) are widely used following stem cell transplantation to support accelerated myeloid recovery and potentially shorten hospital stay. In the recent years, PBSCT is increasingly done in an ambulatory care setting and it is not clear if routine growth factor use has any potential benefit. We undertook this study to compare engraftment kinetics, incidence of febrile episodes, hospitalization duration and other outcomes among transplants done with or without growth factor support Patients and Methods: We included adult patients undergoing PBSCT for myeloma and lymphoma between May 2007 and June 2009 in an ambulatory care setting. Prior to April 2008 (Group-1) all patients received GMCSF 500 mcg/ day starting on day 6 routinely. Since April 2008, there was a shift in clinical practice and routine use of GMCSF was discontinued due to lack of clear evidence regarding benefit. Patients transplanted between April 2008 and June 2009 did not routinely receive GMCSF (Group-2). Typical conditioning regimen for lymphoma was BEAM (BCNU, Etoposide, Cytosine Arabinose, Melphalan) and for multiple myeloma was melphalan 200mg/m2. Patients' demographics details, indication for PBSCT, duration of neutropenic fever, hospital stay, and neutrophil and platelet engraftment were collected from electronic medical records. Neutrophil engraftment is defined as the first day of 2 consecutive days when ANC was > 0.5 × 109/L and platelet engraftment is defined as first of 7 consecutive days on which patient's unsupported platelet count was greater than 20× 109/L. Results: A total of 309 were included in this study, 126 (40%) patients in group-1 (69 with MM, 57 with lymphoma) and 183 (60%) in group-2 (100 with MM, 83 with lymphoma). In group-1, 73 (58%) and in group-2 130 (71%) were male patients. Median age was 59 (29-74) years in group 1 and 58 (24-76) years in group-2. Patients in group 1 received a median of 3.65 (1.1-8.7) versus 4.37 (1.1-9.54) CD34+ x106/kg in group 2 (P =0.005). Median time to neutrophil engraftment was 12 (95% CI 12, 12) for group-1 and 14 (95% CI; 13-14) for group-2 (Kaplan Meier analysis; log rank P < 0.0001). Median estimated time to platelet engraftment was 14 days (95% CI; 13, 15) for group 1 and 13 days (95% CI; 13-13) for group 2 (Kaplan Meier analysis; log rank P 0.007). In group-1 98 (78%) patients developed febrile episodes compared to 117(64%) in group-2 (P = 0.009). Median duration of fever was 2 days (range, 1-8) in group-1 compared to 1 day (range, 1-8) in group-2 (P = 0.0003). The median (range) duration of hospital stay was 7 (1-40) days for group-1 compared to 8 (2-56) days for group-2 (P=NS). There was no significant difference in mortality between these two groups. Conclusion: Routine use of granulocyte growth factors is associated with a shorter time to neutrophil engraftment, but associated with a delay in platelet engraftment. The longer time to neutrophil engraftment without growth factor use does not translate into any increase in frequency of febrile episodes. On the contrary, higher number of febrile days is seen with use of growth factors, likely explained on the basis of drug fever. No difference in the frequency of engraftment syndrome or treatment related mortality was seen. Disclosures: No relevant conflicts of interest to declare.

Abstract BACKGROUND: Complement-mediated thrombotic microangiopathies (TMAs) are a subset of TMAs in which the thrombocytopenia, microangiopathic hemolytic anemia, and end organ damage are caused by mutations in genes encoding the alternative complement pathway. Numerous complement genes have been implicated in complement-mediated TMAs including complement factor H (CFH), CD46 (MCP), complement factor I (CFI), complement component 3 (C3), complement factor B (CFB), factor H related 5 (CFHR5), and thrombomodulin (THBD) among others. Genetic analysis typically yields a mutation in 60% of patients whose TMA is presumed to be mediated by complement dysregulation. However, the description of novel disease-associated variants may increase this proportion. METHODS: A retrospective study of patients with TMAs diagnosed between 2000 and 2014 was performed. TMA diagnosis was made based on thrombocytopenia and evidence of microangiopathic hemolytic anemia. Analysis was performed with Alamut¨ software with additional in silico prediction tools (SIFT, MutationTaster, and Polyphen) for classification of gene variants. Variants of unknown significance (VUS) and likely pathogenic variants were further assessed using several mutation databases, including HGMD, ClinVar, and Factor H database RESULTS: Of patients diagnosed with a TMA, genetic analysis was performed in only a 10% of patients. Of the 29 patients with genetic studies performed, mutations were identified in 18 patients (62%). The majority of the mutations had been described previously in the literature, but four novel variants were identified: three missense and one splice-site. The table below summarizes these variants as well as laboratory findings on presentation. These were two variants of CFH, one variant of CFHR5, and one variant of CFI. In silico modeling of these variants revealed two polymorphisms likely to be pathogenic, one polymorphism likely benign given the lack of predicted splicing changes, and one VUS. Table 1. Protein Mutation Classification Age Sex Hemoglobin (g/dL) Platelets (thousands) Creatinine (mg/dL) CFH c.245-10_245-9dup Likely benign 61 F 11.6 51 6.7 CFH c.476G>A, p.Ser159Asn Likely pathogenic 43 F 9.1 101 9.1 CFHR5 c.1412G>A p.Gly471Glu Likely pathogenic 30 F 9.8 129 4.9 CFI c.1190T>A p.Val397Glu Unknown significance 51 M 9.4 125 6.1 DISCUSSION: With therapy available to target the alternative complement pathway, genetic analysis to identify genetic variants capable of causing complement mediated TMAs is an essential part of the evaluation. This genetic data must be interpreted and correlated with functional analysis and clinical phenotype. The reporting of novel variants in clinical databases, with inclusion of relevant clinical findings, is necessary to accurately classify and verify variants as pathologic mutations or benign polymorphisms. The full understanding of this diverse disease requires a more complete understanding of its genetics. While complement pathway-directed therapies are available, their rational use requires thorough interpretation of laboratory data, including genetic analysis. Disclosures Murray: Mayo Clinic: Patents & Royalties: Patent Application Filed.

Abstract BACKGROUND: Non-hereditary hemolytic anemia of unknown etiology after an exhaustive work-up is commonly known as direct antiglobulin test (DAT)-negative hemolytic anemia. Due to its rarity, limited data are available regarding this condition. We performed this retrospective study to determine the frequency, associated medical conditions, treatments used, and clinical outcome of patients with DAT- negative hemolytic anemia. METHODS: We included adult (age >18 years) patients with DAT-negative hemolytic anemia seen at Mayo Clinic from 1997-2015 who met all of the following criteria: a) hemoglobin (Hb)< 12 g/dL; b) presence of hemolysis (reticulocytosis, elevated lactate dehydrogenase, decreased haptoglobin, and/or elevated indirect bilirubin); c) DAT-negative; and d) unknown etiology of hemolytic anemia after extensive work-up appropriate for clinical context. Remission status after appropriate therapy for perceived hemolysis was defined as follows: a) complete remission (CR; Hb ≥12g/dL and normalization of at least one previously abnormal hemolytic marker); b) partial remission (PR; Hb: 10-11.9 g/dL with evidence of ongoing hemolysis); c) no remission (NR; neither CR nor PR). In order to calculate the relative frequency of DAT-negative hemolytic anemia, we also determined the number of DAT-positive hemolytic anemia cases during the same time period using the above criteria for hemolytic anemia. RESULTS: During the 19-year study period, 24 and 484 patients were diagnosed with DAT- negative and DAT-positive hemolytic anemia, respectively, a ratio of 1:20. Among those with DAT-negative hemolytic anemia, the majority were males (67%) and the median age at diagnosis was 70 years (range, 22-87). Six patients (25%) had pre-existing autoimmune conditions including immune thrombocytopenia (n=3), Crohn's disease (n=2), and Grave's disease (n=1). All patients had negative DAT by conventional method with one patient turning positive at 104 days after initial diagnosis. Enhanced DAT technique using 4°C low-ionic strength saline wash was performed in one case and was negative. In general, peripheral blood smear showed polychromasia, occasional spherocytes, and no schistocytes or bite cells. Additional work-ups performed based on clinical context and proportion of patients tested (all results negative or normal) were as follows: hemoglobin electrophoresis (54%), flow cytometry for paroxysmal nocturnal hemoglobinuria (92%), glucose 6-phosphate dehydrogenase level (67%), osmotic fragility test/eosin-5'-maleimide stain for hereditary spherocytosis (54%), other red blood cell enzymes (46%), computed tomographic scan of the body to look for occult malignancy (46%), and bone marrow biopsy (50%). The median hemoglobin at diagnosis was 8.5 g/dL (range, 4.5-11.8). Fourteen patients (58.3%) required blood transfusion during the course of their disease. Sixteen patients (67%) received prednisone as initial therapy with 19% CR and 38% PR response rates. Subsequent therapies included: rituximab (n=6; 40% PR), cyclophosphamide (n=2; 100% NR), mycophenolate mofetil (n=1; 100% NR), intravenous immunoglobulin (n=2; 100% NR), and splenectomy (n=6; 50% CR and 33.3% PR), respectively. The median follow-up for all cases was 32.9 months (range, 2-433). Six patients (25%) developed hematologic malignancies after a median follow-up of 8.7 months (range, 0.7-29.3), which included primary myelofibrosis (n=2), myelodysplastic syndrome (n=1), mantle cell lymphoma (n=1), non-Hodgkin lymphoma-not otherwise specified (n=1), and T-cell large granular lymphocyte leukemia (n=1). At last follow-up, 9 patients (38%) were in CR and 8 (33%) in PR. Relapses occurred in 67% and 0% of patients who received prednisone and splenectomy, respectively. CONCLUSION: At our institution, DAT-negative hemolytic anemia was approximately 20 times less common than DAT-positive hemolytic anemia. Most patients were treated with either immunosuppressive agents with or without splenectomy. Splenectomy was the most effective treatment. At least a quarter of the patients were eventually diagnosed with hematologic malignancies mostly within a year of DAT-negative hemolytic anemia diagnosis. Routine upfront evaluation for hematologic malignancies might be necessary for these patients. Disclosures No relevant conflicts of interest to declare.