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Background The Coronavirus disease-2019 (COVID-19) is a global pandemic caused by novel coronavirus SARS-CoV-2. Acute respiratory and renal failure as well as systemic coagulopathy are critical aspects of the morbidity and mortality in patients with COVID-19. Heparin Induced Thrombocytopenia (HIT) occurs when IgG antibodies form against platelet factor 4-Heparin complex, resulting in platelet activation and removal, leading to a prothrombotic state. HIT is suspected when there is a platelet count decrease of more than 50% after exposure to heparin, along with hypercoagulability. Clinical Scoring systems like 4T Score (Thrombocytopenia, Timing, Thrombosis, no other cause of Thrombocytopenia) have been developed to assess the pretest probability of HIT. The use of unfractionated heparin, post-orthopedic and post-cardiac surgery state, female gender, and old age are recognized as risk factors for HIT. There is a nine-fold increased risk of developing HIT in patients requiring hemodialysis. ICU patients and patients with VTE without thrombocytopenia are considered to have low pre-test probability for HIT. Studies have shown that only 6% who are investigated serologically for HIT actually have the diagnosis. We conducted this study to assess the incidence and risk factors for HIT in COVID-19 positive patients and its impact on mortality. Methods A retrospective analysis was performed on all patients who were COVID-19 positive and hospitalized between March 1, 2020 and June 26, 2020 at our institution. Patients with intermediate or high suspicion for HIT, based on 4T score of 4 or higher, underwent IgG-specific platelet factor 4(PF4)-dependent enzyme immune assay (EIA). Washed platelet assays such as serotonin release assay (SRA) and heparin-induced platelet aggregation (HIPA) were used as confirmatory tests in cases with intermediate or low optical density (OD) with EIA. The incidence of HIT, its impact on mortality, and positivity of IgG-specific PF4-EIA in COVID-19 patients were studied, and statistical analysis was done with X2 testing. Subgroup analysis was performed based on demographic factors and risk factors for HIT, including exposure to heparin or low molecular weight heparin (LMWH), history of or cancer, recent orthopedic or cardiac surgery, exposure to renal replacement therapy (RRT), and severity of disease (D-dimer >6 ULN, Acute Kidney Injury, ICU admission, and mechanical ventilation requirement). These factors were analyzed by Fisher's exact test to determine their impact on mortality. The hospital course for HIT antibody-positive patients was further analyzed to study the impact of COVID-19 related therapy, such as Remdesivir, Tocilizumab, Hydroxychloroquine, Steroids, and anticoagulation after diagnosis of HIT. Results WEight out of 1265 hospitalized COVID-19 positive patients tested positive for IgG-specific platelet factor 4(PF4)-dependent enzyme immune assay (EIA+). Incidence of EIA+ in COVID-19 patients was 0.6%, which is significantly higher than in the general population 0.2% (p1, 1 was SRA positive) which is significantly higher than confirmation of HIT in nonCOVID-19 patients 6% (p Conclusion Our study indicates incidence of HIT is higher in the COVID-19 population. The incidence of positive EIA for patients with intermediate to high 4T scores is also higher in COVID-19 positive patients. This can be attributed to the cytokine storm and severe sepsis seen in critically ill COVID-19 patients. Our study also suggests that development of HIT can contribute to increased risk for thromboembolic events as well as mortality of COVID-19 patients, however, our study is limited due to small sample size. Therefore, prospective studies are needed to analyze the impact of HIT on morbidity, mortality and long-term outcomes in COVID-19 patients. Table Disclosures No relevant conflicts of interest to declare.

Background The Coronavirus disease-2019 (COVID-19) is a global pandemic. Acute respiratory compromise and systemic coagulopathy cause significant morbidity and mortality. Venous thromboembolism (VTE), which encompasses both deep vein thrombosis (DVT) and pulmonary embolism (PE), as well as arterial thromboembolism (ATE), which includes stroke, are common sequelae described in this patient population. COVID-19 coagulopathy is attributed to severe inflammation and endothelial dysfunction resulting in a prothrombotic state. COVID-19 related treatment has focused on targeting the unregulated inflammatory state in an attempt to decrease incidence of COVID-19 related complications, such as thrombosis. Prophylactic anticoagulation is recommended, and many suggest intermediate to therapeutic anticoagulation in severe COVID-19. However, there is no clear data showing impact of anticoagulation on morbidity and mortality in patients with COVID-19. Methods A retrospective analysis was performed on all COVID-19 patients hospitalized between March 2020 and June 2020 at our institution. Patient charts were individually reviewed to ensure accuracy of data. Thromboembolic events (VTE or ATE) verified by imaging were included in the analysis. The impact of COVID-19 specific treatments such as Remdesivir, Tocilizumab, Hydroxychloroquine, and steroids on incidence of thrombosis was analyzed by using X2 testing. Using logistics regression, we analyzed the effect of prophylactic versus therapeutic anticoagulation received before development of thrombosis on mortality. Results Out of 1265 COVID-19 positive hospitalized patients during our time frame, 138 (10.9%) had thromboembolism. Incidence of 6.3% VTE, 5.6% DVT, 4.8% PE in COVID-19 patients was significantly higher than 0.24% VTE, 0.15% DVT, 0.12% PE in non COVID-19 hospitalized patients as reported by CDC (p Conclusion In Our study the incidence of thrombosis in hospitalized COVID-19 patients was significantly higher than non-COVID-19 hospitalized patients. COVID-19 patients with thrombosis had higher mortality compared to COVID-19 patient without thrombosis, particularly patients with PE. Hispanic patients with COVID-19 and thrombosis experienced a higher mortality rate compared to non-Hispanic patients. The lowest incidence of thrombosis occurred in COVID-19 patients who received steroids, followed by Tocilizumab suggesting that steroids and Tocilizumab may reduce the pro-inflammatory state leading to thrombosis. However, mortality rate was higher in patients who received COVID-19 related treatment, suggesting that these patients likely had severe disease. There was no mortality difference in patients who received prophylactic versus therapeutic anticoagulation prior to thrombosis. Randomized control trials will address the impact of anticoagulation dosing on morbidity and mortality in COVID-19 patients and study the post discharge prophylaxis and long-term outcomes in these patients. Disclosures No relevant conflicts of interest to declare.

The coronavirus disease 2019 (COVID-19) outbreak, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was declared a pandemic on March 11, 2020. This novel virus can cause a rapid progression from cough to acute respiratory distress syndrome and death. Cancer patients infected with COVID-19 were reported to have a 39% incidence of severe events, including admission to intensive care unit (ICU), mechanical ventilation, or death. Patients with hematologic malignancies, especially those undergoing treatment, are a particularly at-risk population due to disease-related impairment of the immune system and chemotherapy-induced neutropenia. The goal of this study is to analyze outcomes of COVID-19 infected patients with hematologic malignancies in order to better understand the impact of SARS-CoV-2 on this vulnerable population. Methods We performed a retrospective analysis on 26 COVID-19 positive patients with hematologic malignancies identified at our center. On July 22, 2020, there were 264 COVID-19 positive patients with hematologic malignancies (including our center's 26 patients) reported to the American Society of Hematology Research Collaborative COVID-19 Registry (ASH RC), a global public reference tool. We extracted our patient's data from each category reported to the ASH RC and compared hospitalization, ICU admissions, and mortality rates between our cohort and the remaining 238 cases. Chi-square test was used for analyses. We also performed a subgroup analysis comparing demographics; type and status of hematologic malignancy, as well as COVID-19 directed treatments between our center's patients and the patients reported to the ASH RC. Results Between March and June 2020, a total of 1265 COVID-19 positive patients were hospitalized at our institution. A significantly higher percentage of COVID-19 patients with hematologic malignancies were hospitalized at our institution compared to the ASH RC (61.5% versus 35.3%, P=. 009). There was no difference in ICU admission rate at our center compared to the ASH RC (23.1% versus 30.2%, P=.45). Significantly less COVID-19 directed therapies were administered at our center compared to the ASH RC (46.2% versus 66.4%, P=.041). Our patients received: 7.7% Remdesivir, 11.5% Tocilizumab, 15.4% hydroxychloroquine, 11.5% azithromycin, 0% convalescent plasma, compared to the ASH RC: 1.7% Remdesivir, 5.5% Tocilizumab, 30.3% hydroxychloroquine, 25.6% azithromycin, 4.6% convalescent plasma. Lastly, our institution had a significantly decreased mortality rate compared to the ASH RC (11.5% versus 29.8%, P=.049). Demographics as well as type and status of hematologic malignancy comparing the two cohorts are shown in Table 1. Conclusions In our comparative analysis, we found that our center's patients were hospitalized significantly more than the ASH RC cohort yet had lower mortality rates. These differences were seen despite similar distribution of malignancy types between the two groups. It should be noted that more patients in our cohort were in remission and none presented at initial cancer diagnosis at the time of infection, which may have contributed to better outcomes. The difference in mortality rates may also be attributed to variance in provider experience, higher percentage of patients >80 years of age reported to the ASH RC, and closer patient monitoring at our center due to a higher hospitalization rate. Differences in ICU admissions were not significant, suggesting a similar rate of severe COVID-19 infection between the two cohorts. Our demographics reflect the urban population we serve with more African Americans and Hispanics compared to the ASH RC. The greater number of COVID-19 directed therapies in the ASH RC cohort compared to ours is likely attributed to the use of convalescent plasma, which was not commonly used as COVID-19 directed treatment at our institution. Limitations of our study include a restricted time frame, small sample size, and the possibility of incomplete datasets within the ASH RC, as stated on the registry's website. In conclusion, we recommend close monitoring and a lower threshold for hospitalizing patients with hematologic malignancies in the setting of COVID-19 infection; however, additional prospective studies are needed to confirm our findings, and further investigate the complications and outcomes of SARS-CoV-2 on this at-risk population. Disclosures Ustun: Kadmon: Honoraria. Shammo:Celgene: Consultancy, Research Funding, Speakers Bureau; BMS: Consultancy, Research Funding, Speakers Bureau; Onconova: Research Funding; Incyte: Consultancy, Research Funding, Speakers Bureau; Apellis: Consultancy; Regeneron: Consultancy; Novartis: Consultancy; Agios: Consultancy; Sanofi: Speakers Bureau; Abbive: Current equity holder in publicly-traded company; Baxter: Current equity holder in publicly-traded company; Takeda: Current equity holder in publicly-traded company; Alexion: Consultancy, Research Funding, Speakers Bureau.

Background Coronavirus disease-2019 (COVID-19) has become a global pandemic causing respiratory compromise, coagulopathy and renal failure in severe cases. Studies demonstrate a high incidence of venous thromboembolism (VTE), up to 69% in patients with severe COVID-19 infection. Coagulopathy in COVID-19 patients is attributed to excessive inflammation and endotheliopathy. Pregnant patients have approximately a 4-fold increase of VTE incidence. This is in part due to an increase in clotting factors and fibrinogen and a decrease in fibrinolytic activity and protein S. Increased stasis and the presence of acquired and inherited thrombophilias can contribute to increased VTE incidence during pregnancy and postpartum period (PP). Risk factors for thrombosis in pregnancy include African American race, heart disease, diabetes, smoking, multiparity, age >35 years, and obesity. Pregnancy/PP state and COVID-19 infection independently increase the risk of VTE which raises concern for an even higher incidence of thromboembolic events in pregnant/PP patients with COVID-19. Data pertaining to hypercoagulability in COVID-19 infected pregnant patients is currently limited. We conducted this study to evaluate the incidence of thrombosis and mortality in pregnant/PP COVID-19 positive patients. Methods A retrospective analysis was performed on all COVID-19 positive hospitalized patients between March 2020-June 2020 at our institution. Pregnant and PP patients were extracted from this cohort and individually chart reviewed by clinicians. Data from the Centers for Disease Control and Prevention on COVID-19 positive pregnant women in the United States from January 22-July 7, 2020 was utilized for comparison analyses. Statistical analysis was performed with chi-square testing. The incidences of thrombosis and mortality were compared between hospitalized COVID-19 positive pregnant/PP patients and hospitalized adult COVID-19 positive women of childbearing age (18-51 years). A subgroup analysis was performed to evaluate risk factors for thrombosis such as demographics, trimester of pregnancy, and single/multiple gestation (Table 1). Anticoagulation and COVID-19 related therapies administered in this cohort were also studied. Results Forty-three pregnant/PP COVID-19 positive patients were identified out of 1265 hospitalized COVID-19 positive patients at our institution. Thrombosis (DVT, PE, or stroke) incidence in our cohort was 0%, which was not significantly different compared to 6.12% incidence of thrombosis in hospitalized COVID-19 positive women of childbearing age (P = .097). The mortality rate of COVID-19 positive pregnant/PP patients was 0%, which was not significantly different compared to the mortality rate of 3.06% in hospitalized COVID-19 women of childbearing age (P = .25). Further, VTE incidence of 0% in hospitalized COVID-19 positive pregnant/PP patients was not significantly different from the 0.1% incidence of VTE in the non COVID-19 pregnant population in the United States (P=.84). Lastly, the 0% mortality rate in COVID-19 positive pregnant/PP patients at our institution was no different than the 0.0169% mortality rate of pregnant women without COVID-19 infections in the United States (P = .93). Conclusion Our study demonstrates no significant difference in incidence of thrombosis and mortality rate between hospitalized COVID-19 positive pregnant/PP patients and hospitalized COVID-19 positive women of childbearing age. There was also no difference in VTE incidence between hospitalized COVID-19 positive pregnant/PP patients and non COVID-19 pregnant women in the United States. The lack of significant difference in both thrombosis incidence and mortality rate in patients who are both COVID-19 positive and pregnant/PP is reassuring and may imply that pregnancy might play a role in decreasing the inflammatory response of COVID-19. During certain phases of pregnancy a high number of macrophages, natural killer cells, and T regulator cells in the decidua have been identified, which could indicate an overall increased systemic immune response, potentially decreasing the dysregulation of the cytokine storm seen in critically ill COVID-19 patients. However, the systemic immunologic changes in pregnancy and the postpartum period remain largely unknown and prospective studies are needed to further investigate the effects of COVID-19 on pregnant patients. Disclosures No relevant conflicts of interest to declare.

Background Sickle cell disease (SCD) is a hemoglobinopathy which manifests clinically as hemolytic anemia and recurrent episodes of pain caused by vaso-occlusion, among other symptoms. Vaso-occlusive crises (VOCs) account for an overwhelming majority of visits to the emergency room (ER) and hospitalizations for patients with SCD (Shah et al. PLoS One 2019). Upregulation of P-selectin, a cellular adhesion protein expressed on activated platelets and endothelial cells, contributes to the pathophysiology of VOCs. Crizanlizumab is a monoclonal antibody administered intravenously that inhibits the interaction of P-selectin with its ligand; it was approved by the Food and Drug Administration (FDA) as a treatment for SCD patients in 2019. In the Phase II SUSTAIN trial, crizanlizumab therapy resulted in a significantly lower rate of sickle cell-related pain crises than placebo (Ataga et al. N Engl J Med 2017). Due to their high-risk status for COVID-19, the pandemic has posed significant challenges for SCD patients to readily access healthcare, including novel therapies such as crizanlizumab. This study aimed to investigate the utility of telemedicine in facilitating access to crizanlizumab as well as compare acute medical care utilization for patients on crizanlizumab six months before initiating therapy and up to six months after their final dose in 2020. Methods All patients (≥18 years of age as of January 1, 2020) with SCD who received crizanlizumab between January 1, 2020 and December 31, 2020 at Rush University Medical Center (RUMC) were included in the final analysis. Demographic features as well as the type of visit when the patient and healthcare provider discussed crizanlizumab treatment was documented. Paired t-tests and Wilcoxon matched-pairs signed rank tests were utilized to compare acute medical care utilization - defined by the number of ER visits, urgent care visits, and hospitalizations - six months prior to initiating therapy and six months after completing the specified therapy regimen for 2020. Simple linear regression models and multiple regression models were conducted to control for sex, BMI, age, insurance, duration of treatment, and type of visit. Results A total of ten patients were included in the final analysis. Five (50%) patients first agreed to proceed with crizanlizumab therapy during a telehealth video visit with their provider, one (10%) made the decision during a telehealth phone visit, and the other four (40%) did so during a traditional office visit. 9 (90%) patients were still on crizanlizumab after June 1, 2020, the date that RUMC urgent care started seeing patients with SCD. The mean number of visits to the ER in the period before initiating therapy was 2.8 (SD=4.26) compared to 2.5 (SD=2.76) after last dose in 2020, however this finding did not achieve statistical significance (p>0.9999). Visits to the urgent care clinic, on average, increased significantly from 1.7 (SD=2.87) in the six months before initiating therapy to 8.2 (SD=11.02) in the six months after ending therapy for 2020 (p=0.0234). The mean number of hospitalizations in the period before initiating therapy was 6.6 (SD=5.19) compared to 4.6 (SD=3.44) in the period after last dose in 2020, however this was also not statistically significant (p=0.2309). None of the covariates had a significant effect on differences in acute care utilization in the period before and after therapy in 2020. Conclusion This study suggests that administration of crizanlizumab therapy did reduce hospitalization and ED visits, but the results could not achieve statistical significance due to our small sample size and short study duration. The number of urgent care visits for these patients, however, did differ significantly from the period before initiating therapy to the six months after the last dose in 2020. This finding can be attributed to the fact that due to the COVID-19 pandemic, urgent care services were made increasingly available to SCD patients beginning on June 1, 2020 to avoid admissions to the ER and hospital. Additionally, our study suggests that during the COVID-19 pandemic, telemedicine played an important role in providing health services to patients with SCD, and it could continue to improve care accessibility for SCD patients after the pandemic. Continued collection and analysis of real-world data is needed to further understand the effect of crizanlizumab therapy on utilization of acute medical care. Figure 1 Figure 1. Disclosures Jain: DOVA: Other: advisory board; Sanofi: Other: advisory board; Argenx: Other: advisory board; Novartis: Speakers Bureau; GBT: Speakers Bureau.

Background The virus SARS-CoV-2, which causes COVID-19 has rapidly spread into a global pandemic. In critically ill patients with the disease, common symptoms include sepsis, severe pneumonia with acute respiratory distress syndrome (ARDS), and complications such as coagulopathy and thrombosis. Many patients with COVID-19 have sequelae such as venous thromboembolism (VTE) including pulmonary embolism (PE) and deep vein thrombosis (DVT) as well as arterial thromboembolism (ATE) including stroke. COVID-19 induced inflammation can induce a prothrombotic state by activating the coagulation cascade; coupled with the immobility of severe and critically ill patients in ICU, making thrombosis common in this patient population. Different blood types in patients include A, B, AB, and O. ABO carbohydrate moieties are genetically inherited and have been linked to predisposing patients to cardiovascular diseases, cancers, and even susceptibility of COVID-19. Blood type positivity and negativity are determined by the Rhesus (Rh) factor, which is a protein found on the surface of red blood cells and is also genetically inherited and linked to higher incidence of certain diseases such as diabetes. Studies have shown a relationship between blood types and increased severity of infection from COVID-19 including increased risk of thrombosis. Blood type A has been shown to have higher severity of disease with O blood type having a lower risk of infection or mortality. This study was done to evaluate if patients with different blood types have increased risk for thrombosis or higher mortality rates with COVID-19 infection. Methods A retrospective analysis was performed on COVID-19 positive hospitalized patients between March 1, 2020 and June 26, 2020 at our institution with reported blood typing. Patients who had a thromboembolism (VTE, DVT, PE, ATE, or stroke) verified by imaging were extracted from this cohort and included in the analysis. The prevalence of different blood types in COVID-19 patients was compared to the general population without COVID-19. The incidence of thrombosis and mortality rate based on blood type was analyzed to understand severity of COVID-19 disease. Statistical analysis was performed using chi-squared testing. Results Among 1265 COVID-19 positive patients during our time frame, 138 patients were identified to have a thrombosis. Of those, 102 patients with thrombosis and 402 without thrombosis had reported blood types that were used for analysis. There was no significant difference in prevalence of blood types in COVID-19 patients (A 34.3%, AB 2.9%, B 16.7%, O 46.1%) to the general nonCOVID-19 population (A32.7%, AB 4.2%, B 14.9%, O 48.1%) (p=0.8572). There was no significant difference in incidence of thrombosis between blood types: A (23.3%), AB (15%), B (20.7%), and O (18.7%) (p=0.6513). When stratifying by Rh factor, there was also no significant difference in incidence of thrombosis by blood types: A- (11.1%), A+ (24.1%), AB- (0%), AB+ (15.8%), B- (25%), B+ (20.3%), O- (18.2%), O+ (18.7%) (p=0.9054). There was also no significant difference in mortality rate between COVID-19 patients based on blood types in our cohort: A (20.7%), AB (15%), B (13.4%), and O (21.8%) (p=0.3747). Conclusion Our study demonstrates that there is no increased prevalence of one blood type over another between COVID-19 patients compared to the general population, showing that patients are not at higher risk for COVID-19 infection based on blood type. There was also no difference between blood types based on incidence of thrombosis. When further stratifying with Rh factor, there was also no difference in incidence of thrombosis based on blood types. This shows that regardless of Rh positivity or negativity, there is no increased risk for thrombosis in COVID-19 patients based on blood type. There is also no difference in mortality in COVID-19 patients based on blood type. Since COVID-19 patients who are critically ill and have more severe disease have higher incidence of thrombosis and higher mortality rates, our study suggests that patients are not at higher risk for severe COVID-19 disease based on blood type. However, this study is also limited due to small sample size, and prospective studies are needed to better understand the relationship between blood type and severity of disease in COVID-19+ patients. Disclosures No relevant conflicts of interest to declare.

Patients with a personal or familial history of thromboembolism are considered at higher risk for thromboembolic disease after knee arthroplasty. While it remains unclear why some patients develop deep vein thrombosis (DVT) or pulmonary embolism (PE) despite similar operative procedures and the same prophylactic regimen, we presume one explanation would be genetic predisposition.We determined the frequency of 12 factors including antithrombin III activity, prothrombin gene mutations, and the presence of phospholipid antibodies in a high-risk patient cohort and compared those findings with the known prevalence in the population at large.Patients identified preoperatively as having a personal or familial history of DVT and/or PE were referred for hemostatic serum and genetic tests, including % antithrombin III activity (ATIII), protein C and protein S activities, APC resistance, Factor V gene (Leiden) mutations, prothrombin gene mutations, lupus anticoagulant antibody presence, cardiolipin antibody presence, phosphatidyl antibody presence, β2-glycoprotein antibody presence, and serum homocysteine and lipoprotein(a) levels The frequencies of varying abnormalities were identified and compared to the prevalence reported in the literature.Forty-three of 1944 patients undergoing knee arthroplasty had a history of DVT or PE. Sixteen of 43 (37%) patients had an abnormality and eight of these (19%) had two or more abnormalities. The frequency of nine of the 12 tests appeared to be greater in this cohort than in the population at large.Patients with a personal or familial history of DVT or PE appear to have a high frequency of hereditary prothrombotic abnormalities. Preoperative evaluation by a hematologist may be warranted in patients with a personal or familial history of DVT or PE as the postoperative anticoagulation protocols may be altered and identification of these abnormalities may affect a patient's risk for other disease states.Level IV, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Remicade, a chimeric human-murine monoclonal antibody capable of neutralizing tumor necrosis factor alpha was given to 37 low-risk myelodysplastic syndromes (MDS) patients in two cohorts; 5 and 10 mg/kg intravenously every 4 weeks for 4 cycles. Median age was 68 years, 33 had primary MDS, 14 had refractory anemia (RA), 14 RA with ringed sideroblasts, 9 RA with excess blasts. Nine patients stopped therapy prior to completing 4 cycles, 3 from cohort 1 and 6 from cohort 2 and response was evaluated using the International Working Group criteria in 28 patients who completed the 4 cycles. Six patients showed disease progression, 14 had stable disease and 8 showed hematologic responses, 3/15 (20%) in cohort 1 and 5/13 (38%) in cohort 2. Two patients had multi-lineage responses, 2 had > 100% increase in absolute neutrophils, I had > 1 gm/dl increase in hemoglobin, I had reduction in blasts from 7% to 1%, and 2 had minor cytogenetic responses ( > 50% reduction in + 8 and 20q-metaphases respectively). We conclude that Remicade may have a variety of activities in low risk MDS patients, is well tolerated with a high patient compliance, and may be considered for combination therapy in the future.

Twenty-eight myelodysplastic syndromes (MDS) patients were treated with arsenic trioxide (ATO) and thalidomide. Seven patients responded including one complete hematologic and cytogenetic response and one with regression in spleen size. Two trilineage responses were seen in patients with inv(3)(q21q26.2). Three of five patients who had high pre-therapy EVI1 levels showed unexpectedly good responses while two died early in the first cycle. In vitro studies using 32Dcl3 cells forced to express EVI1 confirmed increased sensitivity of these cells to ATO. Both low/high risk MDS may benefit significantly from therapy with ATO/thalidomide, and those with high pre-therapy EVI1 expression may be uniquely sensitive.

Thirty patients with myelodysplastic syndromes (MDS) were treated with thalidomide at 100 mg/d p.o., increased as tolerated to 400 mg/d for 12 weeks. Levels of apoptosis, macrophage number, microvessel density (MVD), tumour necrosis factor alpha (TNF-alpha), transforming growth factor beta (TGF-beta), interleukin 6 (IL-6), vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) were determined in the serum, bone marrow (BM) plasma and BM biopsies before and after therapy. Pretherapy biological characteristics of MDS patients were compared with similar studies performed in 11 normal volunteers. Ten patients demonstrated haematological improvement in the erythroid series, six becoming transfusion independent. Responders had a higher pretherapy platelet count (P < 0.048) and lower BM blasts (P < 0.013). Median time to response was 10 weeks, and four remain in remission beyond a year. Pretherapy MDS BMs showed higher MVD (P < 0.001) and TGF-beta (P < 0.03) and higher serum TNF-alpha (P < 0.008) compared with normal control subjects. After therapy, only BM TGF-beta decreased significantly (P < 0.002). Pretherapy haemoglobin was directly related to serum VEGF (P < 0.001) in responders and inversely related in non-responders (P < 0.05), suggesting the possibility that angiogenesis may be a primary pathology in the former and a consequence of anaemia-induced hypoxia in the latter. We conclude that thalidomide has important clinical and biological effects in at least a subset of MDS patients, but the precise mechanism of its action remains unknown and requires further study including a larger number of patients.

We used bone marrow biopsies instead of mononuclear cells to maintain long-term cultures from 103 patients belonging to all five sub-categories of myelodysplastic syndromes (MDS), as well as 12 normal controls. By week 4, 30-50% confluency was reached and could be maintained for up to 12 weeks with 100% confluency. The four prominent cells were fibroblasts, macrophages, endothelial cells and adipocytes. Immunohistochemical and electron microscopic studies provided lineage confirmation. Normal hematopoiesis was well supported by MDS stroma. Neither the FAB nor cytogenetics was co-related with the potency of growth. MDS stroma appears to be both morphologically and functionally normal.

Twenty patients with poor prognosis AML and four patients in the blastic phase of a myeloproliferative disorder were treated with two 'pulses' of therapy each consisting of two doses of high dose araC (separated by 12 h) followed by a single dose of mitoxantrone. The pulses were separated by 96 h. Amifostine was then administered tiw. The median age of the population was 68 years with 88% of patients having had either a prior MDS, MPD or toxic exposure. The acute leukemia of 58% of patients either entered a CR or reverted to preleukemic state. For patients under 70 years of age, treatment produced 62% CRs with a leukemia free decision marrow in 77%. For patients over 70 years the CR rate was 27% with 36% of patients having a leukemia free decision marrow.

Rates of proliferation and apoptosis as well as expression of tumor necrosis factor alpha (TNF-alpha), transforming growth factor beta (TGF-beta) and the number of macrophages were measured in bone marrow (BM) biopsies of 33 patients who presented with hypocellular (cellularity30%) myelodysplastic syndromes (MDS). Results showed that 2/3 of the patients had high apoptosis, high cytokine levels and large number of macrophages in their biopsies while 1/3 did not. Apoptosis and TNF-alpha levels were directly related (r = 0.583, P = 0.003, n = 24) as was apoptosis and the degree of anemia (P = 0.033, n = 18). A subgroup of patients with abnormalities of chromosomes 5 or 7 had higher platelets (P = 0.026) and higher apoptosis (P = 0.038) when compared with the rest of the group. Eight patients had no evidence of apoptosis and almost no detectable TNF-alpha in their biopsies. We conclude that within the hypocellular variant of MDS, there may be two distinct sub-groups of patients, one who present with high cytokine-mediated intramedullary apoptosis and the other who may be better characterized as having a stem-cell failure defect since they showed no evidence of apoptosis.

Extensive apoptosis or programmed cell death (PCD) of both hematopoietic (erythroid, myeloid, megakaryocytic) and stromal cells in myelodysplastic syndromes (MDS) cancels the high birth-rate resulting in ineffective hematopoiesis and has been demonstrated as the probable basis for peripheral cytopenias in MDS by our group. It is proposed that factors present in the microenvironment are inducing apoptosis in all the cells whether stromal or parenchymal. To investigate this hypothesis further, bone marrow biopsies from 46 MDS patients and eight normal individuals were examined for the presence of three cytokines, tumor necrosis factor-alpha (TNF-alpha), transforming growth factor-beta (TGF-beta) and granulocyte macrophage-colony stimulating factor (GM-CSF) and one cellular component, macrophages, by the use of monoclonal antibodies immunohistochemically. Results showed the presence of TNF-alpha and TGF-beta in 41/46 and 40/46 cases of MDS respectively, while only 15 cases showed the presence of GM-CSF. Further a significant direct relationship was found between the degree of TNF-alpha and the incidence of PCD (p= 0.0015). Patients who showed high PCD also had an elevated TNF-alpha level. Thus, the expression of high amounts of TNF-alpha and TGF-beta and low amounts of the viability factor GM-CSF may be responsible for the high incidence of PCD leading to ineffective hematopoiesis in MDS. Future studies will be directed at attempting to reverse the lesion in MDS by using anti-TNF-alpha drugs such as pentoxifylline.

Our previous studies using in situ end labeling (ISEL) of fragmented DNA revealed extensive apoptotic cell death in the bone marrows (BM) of patients with myelodysplastic syndromes (MDS) involving both stromal and hematopoietic cells. In the present report we show greater synthesis of interleukin-1 beta (IL-1 beta) in 4 hour cultures of density separated BM aspirate mononuclear (BMAM) cells from MDS patients as compared to the cultures of normal BM from healthy donors or lymphoma patients (1.7 +/- 0.37 pg/10(5) cells, n = 29 v 0.42 +/- 0.24 pg/10(5) cells, n = 11, respectively, P = .049). Further, these amounts of IL-1 beta in MDS showed a significant correlation with the extent of apoptosis detected by ISEL in corresponding plastic embedded BM biopsies (r = .480, n = 30, P = .007). In contrast normal BMs did not show any correlation between the two (r = .091, n = 12, P = .779). No significant correlation was found between the amounts of IL-1 beta and % S-phase cells (labeling index; LI%) in MDS determined in BM biopsies using immunohistochemistry following in vivo infusions of iodo- and/or bromodeoxyuridine. Neither anti-IL-1 beta antibody nor IL-1 receptor antagonist blocked the apoptotic death of BMAM cells in 4 hour cultures (n = 5) determined by ISEL (apoptotic index; AI%), although the latter led to a dose-dependent accumulation of active IL-1 beta in the culture supernatants. On the other hand, a specific tetrapetide-aldehyde inhibitor of ICE significantly retarded the apoptotic death of BMAM cells at 1 mumol/L in 5/6 MDS cases studied (AI% = 2.99 +/- 0.30 in controls v 1.58 +/- 0.40 with ICE-inhibitor, P = .05) and also reduced the levels of active IL-1 beta synthesized (5.59 +/- 2.63 v 2.24 +/- 0.93 pg/10(6) cells, respectively). In normal cells, neither IL-1 blockers nor the ICE inhibitor showed any effect on the marginal increase in apoptosis observed in 4 hour cultures. Our data thus suggest a possible involvement of an ICE-like protease in the intramedullary apoptotic cell death in the BMs of MDS patients.

Cell-cycle kinetics were measured in situ after infusions of iododeoxyuridine and/or bormodeoxyuridine in 50 patients with myelodysplastic syndromes (MDS) and the median labeling index in bone marrow (BM) biopsy samples was 28.6%. Unfortunately, 26 of 50 patients showed that > or = 75% of hematopoietic cells of all three lineages were undergoing programmed cell death (PCD) in their biopsy samples as shown by the in situ end labeling (ISEL) technique. Ten patients had 1/3 and eight had 2/3 ISEL+ cells. Stromal cells were frequently ISEL+ and often S-phase cells were also found to be simultaneously ISEL+. Nucleosomal DNA fragments as a ladder in agarose gel were present in BM aspirates of four patients who showed high ISEL and were absent in two who had no ISEL staining in biopsy samples, but only when DNA was extracted after a 4-hour in vitro incubation in complete medium. Therefore, laddering data confirmed the ISEL findings that the majority of hematopoietic cells in MDS are in early stages of PCD. We conclude that extensive intramedullary cell death may explain the paradox of pancytopenia despite hypercellular marrows in MDS patients. Investigating approaches that protect against PCD in some MDS subsets would be of interest.

Six patients, five with acute myeloid leukemia (AML) and one with a myelodysplastic syndrome (MDS), were found to have monosomy 7 by conventional cytogenetics at diagnosis. Repetitive DNA sequences from the heterochromatic region of human chromosomes 1 and 7 were used as probes for in situ hybridization experiments on interphase cells of these patients. A double hybridization protocol was used to reveal the particular chromosomes as distinct spots or clusters of signals within interphase nuclei. The chromosome 1 sequence served as an internal control. Simultaneous detection of the sequences showed the presence of two normal number 1 chromosomes and a missing 7 chromosome from individual cells. While cytogenetic preparations showed only -7 metaphases in 3 AML and 1 MDS patients, in situ hybridization of interphase cells showed many normal cells as well as the presence of -7 in fully mature granulocytes. One AML patient studied in remission showed only normal metaphases yet had 9% interphase cells with a missing 7 and relapsed within 3 months. We conclude that examination of interphase cells by in situ hybridization provides clinically useful data since every cell including mature granulocytes can be examined, the lineage of a cell can be determined, and efficacy of differentiation therapy can be evaluated.

Antiphospholipid syndrome has received considerable attention from the medical community because of its association with a number of serious clinical disorders, including arterial and venous thromboembolism, acute ischemic encephalopathy, recurrent pregnancy loss, thrombocytopenia, and livido reticularis. It can occur within the context of several diseases, mainly autoimmune disorders, and is then called secondary antiphospholipid syndrome. However, it may be also be present without any recognizable disease, or so-called primary antiphospholipid syndrome. There is no defined racial predominance for primary antiphospholipid syndrome, although a higher prevalence of systemic lupus erythematosus (SLE) occurs in African Americans and the Hispanic population. Multiple terms exist for this syndrome, some of which can be confusing. Lupus anticoagulant syndrome, for example, is a misleading term, because patients may not necessarily have SLE, and it is associated with thrombotic rather than hemorrhagic complications. To avoid further confusion, antiphospholipid syndrome is currently the preferred term for this clinical syndrome. Antiphospholipid antibodies are found in 1% to 5% of young healthy control subjects; however, the incidence increases with age and coexistent chronic disease. The syndrome occurs most commonly in young to middle-aged adults; however, it also can occur in children and the elderly. Among patients with SLE, the prevalence of antiphospholipid antibodies is high, ranging from 12% to 30% for anticardiolipin antibodies, and 15% to 34% for lupus anticoagulant antibodies. In general, anticardiolipin antibodies occur approximately five times more often then lupus anticoagulant in patients with antiphospholipid syndrome. This syndrome is the most common cause of acquired thrombophilia, associated with either venous or arterial thrombosis or both. It is characterized by the presence of antiphospholipid antibodies, recurrent arterial and venous thrombosis, and spontaneous abortion. Rarely, patients with antiphospholipid syndrome may have fulminate multiple organ failure, or catastrophic antiphospholipid syndrome. This is caused by widespread microthrombi in multiple vascular beds, and can be devastating. Patients with catastrophic antiphospholipid syndrome may have massive venous thromboembolism, along with respiratory failure, stroke, abnormal liver enzyme concentrations, renal impairment, adrenal insufficiency, and areas of cutaneous infarction. According to the international consensus statement, at least one clinical criterion (vascular thrombosis, pregnancy complications) and one laboratory criterion (lupus anticoagulant, antipcardiolipin antibodies) should be present for a diagnosis of antiphospholipid syndrome. The hallmark result from laboratory tests that defines antiphospholipid syndrome is the presence of antibodies or abnormalities in phospholipid-dependent tests of coagulation, such as dilute Russell viper venom time. There is no consensus for treatment among physicians. Overall, there is general agreement that patients with recurrent thrombotic episodes require life-long anticoagulation therapy and that those with recurrent spontaneous abortion require anticoagulation therapy and low- dose aspirin therapy during most of gestation. Prophylactic anticoagulation therapy is not justified in patients with high titer anticardiolipin antibodies with no history of thrombosis. However, if a history of recurrent deep vein thrombosis or pulmonary embolism is established, long-term anticoagulant therapy with international normalized ratio (INR) of approximately 3 is needed.

Thalidomide was administered to 83 patients with myelodysplastic syndrome (MDS), starting at 100 mg by mouth daily and increasing to 400 mg as tolerated. Thirty-two patients stopped therapy before 12 weeks (minimum period for response evaluation), and 51 completed 12 weeks of therapy. International Working Group response criteria for MDS were used to evaluate responses. Intent-to-treat (ITT) analysis classified all off-study patients as nonresponders. Off-study patients belonged to a higher risk category (P =.002) and had a higher percentage of blasts in their pretherapy bone marrow than patients who completed 12 weeks of therapy (P =.003). No cytogenetic or complete responses were seen, but 16 patients showed hematologic improvement, with 10 previously transfusion-dependent patients becoming transfusion independent. Responders had lower pretherapy blasts (P =.016), a lower duration of pretherapy platelet transfusions (P =.013), and higher pretherapy platelets (P =.003). Among responders, 9 had refractory anemia (RA); 5 had RA with ringed sideroblasts; and 2 had RA with excess blasts. By ITT analysis, 19% of patients (16 of 83) responded, and when only evaluable patients were analyzed, 31% (16 of 51) responded. It was concluded that thalidomide, as a single agent, is effective in improving cytopenias of some MDS patients, especially those who present without excess blasts. (Blood. 2001;98:958-965)

Spontaneous intramedullary apoptosis was measured in bone marrow (BM) biopsies of 175 patients with myelodysplastic syndromes (MDS) using in situ end-labeling (ISEL) of fragmented DNA. Two groups of high (n = 71) versus low (n = 43) levels of apoptosis were identified while 61 patients were ISEL-negative. Semiquantitative assessment of 3 cytokines, the number of macrophages and in vivo labeling indices (LI) were also determined from consecutive sections of the biopsy. Patients with high apoptosis levels tended to have a high LI (p = 0.013), more macrophages in their BM biopsies (p = 0.006) and higher tumor necrosis factor alpha (TNF-α) levels (not significant) compared to patients with no apoptosis. In addition, low risk MDS patients had significantly lower rates of apoptosis (p = 0.047) and lower levels of TNF-α (p = 0.055) compared to high-risk MDS patients. We conclude that the genesis of cytopenias in MDS is of multifactorial origin and that cytokine-associated apoptosis clearly identifies a distinct biological subgroup of patients who may benefit selectively by use of anti-cytokine therapies.

Forty-three patients with myelodysplastic syndromes (MDS) were treated with a combination of pentoxifylline and ciprofloxacin (PC) with the addition of dexamethasone (PCD) in 18 patients who failed to respond to PC. There were 15 females and 28 males, and the median age was 67 years. A total of 18 patients either showed a hematopoietic improvement, a partial or complete cytogenetic response or a combination of both for an overall response rate of 42%. Seven PC only patients responded, four showing hematologic improvement, two cytogenetic responses and one patient showing a combined response. This 16% response rate to PC was increased to 61% by the addition of dexamethasone with 11/18 patients showing a response. Four of the 7 patients who responded initially to PC were given dexamethasone after at least 12 weeks of PC therapy, and only 1 showed a further improvement in response. Thus, we conclude that the combination of PCD provides an encouraging novel approach to treating MDS. The mechanism of action is probably related to the suppression of a veriety of cytokines which in turn attenuate the excessive intramedullary apoptotic death of hematopoetic cells in MDS, an observation which has been speculated to be the basis of the paradox of variable cytopenias despite cellular marrows in MDS. Larger numbers of patients need to be treated and followed for longer periods to determine the true efficacy of this therapy, especially the nature and duration of the cytogenetic responses.

PubMedID: 9444948 The incidence of aplastic anemia among hospitalized adult patients was prospectively determined in this first study in Turkey. New cases of aplastic anemia among patients 14 years and older who were admitted to the study centers were included in a 3 year survey. Seventy-three patients fulfilled the diagnostic criteria, yielding a mean annual incidence rate of 1.14 cases in 103 admissions. The male-to-female ratio of the cases (1.6:1) differed from the almost equal ratio of the larger population of Turkey. The median age was 30 years and females were younger at diagnosis. The age distribution of the cases was different from that of the population; showing two incidence peaks in both sexes. The majority of the patients (89%) had severe disease. TAG-0755 Materials Research Society Acknowledgements-The authorsa re gratefult o Professor N. Akman,P rofessoYr . Aydm,P rofessoSr . DtindarP, rofessor B. Ferhanoglu,A ssociateP rofessor0 . Gzcebe, Associate Professor0 . Gzdemir,P rofessorK . Gzerkana nd Associate ProfessorT . Soysal for providingp atientst o the studya nd ProfessorH asanY azrci for his valuables uggestionfso r the studya nda lso Mrs GtinseliD um,M S Figen Aydogana ndM S NurcanG edik for their secretariaal ssistanceTs.h e studyw as supportedb y TL&ITAK (The Scientific and Technical Research Council of Turkey), grant no: TAG-0755

This study was made to show the effects of acute leukemia (AL) and cytostatic drug therapy on chromosomes by sister chromatid exchange (SCE) analysis. Metaphase preparations from peripheral blood lymphocytes (PBL) of 15 patients [13 with acute nonlymphocytic leukemia (ANLL) and one with acute lymphocytic leukemia (ALL), and one with Hodgkin's disease (HD)] were harvested before and after treatment. Mean SCE frequency in the cells was 12.07 +/- 0.15 before therapy and was 14.04 +/- 0.32 after therapy as compared with 7.87 +/- 0.60 in controls. SCE values of patients with AL were significantly higher than those of controls, and this was more conspicuous in the cells that had undergone anticancer treatment.

Introduction: Achieving improvements in survival and reducing relapse remains a challenge in acute myelogenous leukemia (AML) patients. This study evaluated the in vitro efficacy of the active form of novel agent sapacitabine, 2′-C-Cyano-2′-deoxy-1-α-d-arabino-pentofuranosylcytosine (CNDAC, Cyclacel Ltd, Dundee, UK), as compared to current chemotherapeutic drugs Ara-C (Cytarabine) and Mitoxantrone (Mit, synthetic anthracenedione) using two AML cell lines, HL-60 (promyelocytic) and THP-1 (monocytic), as well as bone marrow (BM) and peripheral blood (PB) cells collected from 5 AML patients. Methods: Cells lines and AML patient cells were treated in vitro with Ara-C (1-100 µM), CNDAC (1-100 µM) or Mit (0.005-0.5 µM) for 4 days. During treatment, HL-60, THP-1, and PB AML cells were cultured in suspension. BM AML cells were co-cultured with M2-10B4 mouse stromal cells. Cell lines were assessed immediately. BM and PB AML cells were assessed after an additional 3, 7, or 31 days of co-culture on M2-10B4 cells. Treated cells were assessed for sensitivity (cell death by trypan blue and apoptosis by 7AAD/Annexin V) as compared to untreated cells and IC50 values (50% of maximum possible effective response) were calculated. Results: In HL-60 cells, the amount of cell death was greater with CNDAC compared to Ara-C at all doses tested (p≤0.05, n=3). In THP-1 cells, CNDAC and Mit, but not Ara-C, induced a significant apoptotic response. At a 10-fold lower seeding density, which correlates to higher proliferation rates, the response of THP-1 cells to Ara-C, CNDAC and Mit reached significance compared to untreated cells (p≤0.05, n=3). However, the IC50 values for the 3 drugs in THP-1 cells reflect the observation that this cell line is in essence resistant to AraC (IC50 = 7.77 µM) but sensitive to CNDAC (IC50 = 0.929 µM) and Mit (IC50 = 0.003 µM). Using PB AML cells, a significant response to 1 µM CNDAC and 0.005 µM Mit but not 1 µM Ara-C was observed, as compared to untreated cells at all days post drug removal (p≤0.05, n=5). A significantly greater apoptotic response to CNDAC was observed compared to Ara-C at low doses (p≤0.05, n=5). At higher doses, all 3 drugs induced significant cell death (p≤0.05, n=5). In BM AML cells, overall survival with 1 µM CNDAC or 0.005 µM Mit, but not 1 µM Ara-C, was significantly less than untreated cells 31 days post-treatment (p≤0.05, n=5). Higher doses induced cell death (p≤0.05, n=5) with all 3 drugs. Conclusion: Low dose CNDAC and Mitoxantrone induce a greater response than low dose Ara-C in patient AML cells and AML cell lines. CNDAC also exhibits a greater activity in cell lines (THP-1) that are less sensitive to Ara-C. The in vitro sensitivity of AML cells to CNDAC supports the ongoing clinical evaluation of sapacitabine in AML patients. Future studies are warranted to assess the potential for combining sapacitabine with Ara-C and/or Mitoxantrone, with an emphasis on cells and patients insensitive to Ara-C treatment. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4668. doi:1538-7445.AM2012-4668

The paradox of myelodysplastic syndromes (MDS) which present with pancytopenias despite cellular bone marrows (BM) was investigated by conducting detailed studies of proliferation and apoptosis in 89 MDS patients. Our results demonstrated a rapid rate of both proliferation as well as apoptosis. Levels of three cytokines, tumor necrosis factor-alpha (TNF-alpha), transforming growth factor-beta (TGF-beta) and interleukin-1 beta (IL-1 beta) were measured in the same patients. High levels of TNF-alpha were found to correlate with high levels of apoptosis in 83 MDS patients (P = 0.0045). We propose a dual role for TNF-alpha (or other cytokines) in the pathogenesis of MDS. On the one hand, TNF-alpha induces apoptosis in the maturing cells causing pancytopenia while on the other, it stimulates the proliferation of the primitive progenitors accounting for the hypercellular BM frequently seen in MDS. A new model for MDS is presented. The initial abnormality probably affects a primitive hemopoietic progenitor which acquires a growth advantage leading to monoclonal hemopoiesis, which in turn makes these cells susceptible towards acquiring additional mutations and appearance of cytogenetically marked (or unmarked) clones. Cytokines such as TNF-alpha whose source is presently unknown, then contribute towards the clinical syndrome of pancytopenia and hypercellularity.

A patient with acute myelofibrosis developed acute leukemia during the course of her disease. Light microscopic examination showed that the cells were lymphoblasts. The presence of terminal deoxynucleotidyl transferase and T- and B-lymphocyte markers suggested that the malignancy was of immature lymphoid cell origin. Terminal leukemic transformation in some cases of acute myelofibrosis may be of a lymphoid nature and, thus, less toxic chemotherapy could be used with a better prognosis.

A patient with acute myeloid leukemia received bromodeoxyuridine (BrdU) prior to remission induction therapy. Prior to therapy only leukemic blast cells were found to be labeled. The marrow was aplastic by day 17 with the marrow cavity being devoid of BrdU labeled cells. In contrast rare BrdU containing cells were noted in the paratrabecular and endosteal regions. As the marrow recovered, many regenerating cells contained BrdU, implying that normal stem cells must have been in S-phase at the time of BrdU infusion, and repopulation of marrow may be accounted for by the activity of only a few clones in remission.

Twenty-five patients with a diagnosis of myelodysplastic syndromes (MDS) were randomized to either begin therapy with pentoxifylline, ciprofloxacin and dexamethasone (PCD) immediately (10 patients) or after a 12 week observation period (control arm, 15 patients). PCD was administered with the goal of suppressing cytokine-induced excessive intramedullary apoptosis of hematopoietic cells. No marked fluctuations of blood counts were noted during the period of observation. Twenty-two patients completed at least 12 weeks of therapy: 18/22 showed some type of hematologic response, 9/18 showing an improvement in absolute neutrophil count only (p =0.001) and 9/18 showing multi-lineage responses. No unique category of MDS responded better, however 19/25 patients had refractory anemia (RA)/RA with ringed sideroblasts. The median time to response was 6 weeks and 3/18 responding patients maintained their responses beyond a year. We conclude that hematologic improvement in response to PCD therapy supports the validity of this unique anti-cytokine approach. Future trials should combine PCD therapy with established approaches (growth factors/chemotherapy) and also should focus on identifying more effective ways of suppressing the pro-apoptotic cytokines in MDS.

Twenty five patients with AML who had neither a history of toxic exposure or myelodysplasia were treated with a remission induction regimen consisting of two pulses of chemotherapy separated by 96 hrs. Each pulse consisted of cytarabine 2gm/m(2) (at t=0 and t=12 hrs) with mitoxantrone [30mg/m(2) ] administered immediately after the second cytarabine administration. Amifostine was administered three times a week [on Monday, Wednesday, and Friday] until the outcome of therapy was known. This regimen induced complete remissions in 15 of 17 patients less than 70 years of age and in 5 of 8 patients older than 70 years.