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Rationale: Treatment of acute myelogenous leukemia (AML) remains a challenge in elderly populations, those with comorbid conditions, and patients with poor performance status indices. The optimal choice for induction therapy as well as further agent selection is unclear, and current guidelines recommend enrollment in a controlled clinical trial. Methods: Institutional cases of AML via an electronic medical record query performed in November 2017 containing cases of AML in patients 65 years of age or greater from 01/01/2000 to 06/21/2017 were extracted. Instances of acute myelogenous leukemia were identified by ICD codes. Age, gender, induction therapy, cytogenetics, molecular analyses, and overall survival were collected. Results: A total of 61 cases of AML in patients aged 65 or greater were identified, with those having incomplete data being excluded from analysis. The mean age of included patients was 78.9 years of age, 35 were male and 26 were female. 60 confirmed deaths were recorded. 26 patients received conventional 7+3 (42.6%), 22 received a hypomethylating agent (HMA) (31.1%), 16 (26.2%) did not receive treatment. Conclusion: Our institutional data showed overall survival was significantly longer when treated with 7+3, 354 days (95% CI [93, 614]), vs. 61 days (95% CI [15, 107]). Similarly, OS was significantly longer when treated with HMA, 303 days (95% CI [23, 583]). Risk of death, accordingly, was as follows: 7+3 HR .347 (.179-.672), HMA HR .348 (.173-.703). Our institutional mortality data reasonably reflected SEER data analysis reported by Medeiros et al concerning untreated patients, but trended toward a greater OS for those treated with 7+3 or HMA. Registry data, as well as our institutional data, demonstrate a survival benefit to intensive chemotherapy and palliative chemotherapy, while controlled trials have not shown this benefit consistently in elderly populations. Practices regarding induction therapy vary greatly between institutions. Determination of which elderly patients to treat with intensive therapy remains difficult. References: Almeida AM, Ramos F. Acute myeloid leukemia in the older adults. Leuk Res Rep. 2016;6:1-7. Eleni LD, Nicholas ZC, Alexandros S. Challenges in treating older patients with acute myeloid leukemia. J Oncol. 2010;2010:943823. Medeiros BC, Satram-hoang S, Hurst D, Hoang KQ, Momin F, Reyes C. Big data analysis of treatment patterns and outcomes among elderly acute myeloid leukemia patients in the United States. Ann Hematol. 2015;94(7):1127-38. Disclosures Chisti: Eli Lilly: Speakers Bureau; Medscape: Honoraria; UpToDate: Honoraria.

Background: Antigens like CD20 antigen, are established targets for antibody therapy with monoclonal antibodies (mAb) like Rituximab. Mixed clinico-pathological responses to mAb have been reported either due to presence of antibodies, rapid clearance or low density of target receptor/antigens. This demands need for an assay to monitor serum mAb therapeutic levels to ensure appropriate dosage. Enzyme-linked immunosorbent assay (ELISA) is still the most widely used technique to detect mAb level in human serum which is expensive and time consuming. Understanding properties and interactions of antigens is quintessential for developing better targeted agents and overcoming resistance. Flow cytometry is still the most widely used technique to detect CD20 level in human serum which is expensive, time consuming and does not reveal any details of interaction between the molecules. We have developed a new innovative biosensor based novel technique to not only monitor levels but also study real time interaction of antigens with antibodies using QCM Piezo-immunosensor. This quantitative label free peptide based assay can be used to characterize cell surface antigen, to study antigen- antibody interactions and obtain understanding of mechanisms of resistance to therapy. Method:Mimotope was used as a substitute for the antigen like CD20 and HER2 receptor protein in QCM assays to detect mAb level. The validation samples were prepared from the standard T solution in 10% human serum at three concentrations (10, 20 and 40 ug/ml). The changes in frequencies (ΔF) of sera from 3 female patients were obtained by calculating the differences between frequency shifts in pre and post mAb infusion. mAb level was calculated by equation, (ΔF +1.0022) ÷ 0.9997 μg / ml. The real-time processes of attachment of Cells like Raji cells on the gold electrode and the subsequent binding of antibody like Rituximab to the cells were studied using QCM biosensor. The interaction between Antigen and Antibody led to the increased resonant frequency shifts (df0) in the studied antibody concentration range from 5 to 250 μg mL-1 . Control experiments using other therapeutic antibodies (i.e., Trastuzumab and Bevacizumab) and different cells (i.e., T cells and endothelial cells) proved very specific interaction between Rituximab and CD20 antigens on B cells Results: Antigen and Antibody binding was very specific. This binding decreased the electrochemical activity and stability of the cells, supporting the cell lysis mechanisms of action of Rituximab. We showed that assay sensitivity was dependent upon the amino acids used to tether and link the peptide to the sensor surface and the buffers used. QCM assay was capable of detecting mAb like Trastuzumab serum level as low as 0.038 nM (linear operating range of 0.038-0.859 nM). The time frame of assay was 20-30 minutes. These results were in concordance with previously published results using ELISA. We have shown a systematic approach for using QCM technique to quantify the apparent binding constant between antigen and antibody can reveal antigen density. Conclusion: We have established a low cost, highly sensitive, fast, synthetic peptide based QCM assay which could be used as a basis for developing a new generation of affinity-based Immunosensor assays to monitor mAb serum levels like Rituximab, Trastuzumab and other monoclonal antibodies, helping physicians to determine the clinical efficacy of these drugs and ensuring appropriate dosages. Moreover antigen density and interactions of antigens with respective monoclonal antibodies like CD20 with Rituximab will help physicians to determine the clinical efficacy and resistance mechanisms to targeted antibodies like Rituximab and Ofatumumab. This could be used as a basis for developing a new generation of affinity-based Immunosensor assays. Our study shows that peptide mimotopes have potential benefit in sensor applications as the peptide-peptide interactions in the peptide mimotopes could be manipulated by the addition of functional groups to the peptide to influence binding of the target protein as well as for surface immobilization. Disclosures No relevant conflicts of interest to declare.

Background: CD20 antigen, expressed on greater than 90% of B-cell lymphomas, is an established target for antibody therapy with monoclonal antibodies like Rituximab, which can selectively deplete CD20-expressing cells in peripheral blood and lymphoid tissues. Understanding properties and interactions of CD20 antigens is quintessential for developing better targeted agents and overcoming resistance. It has not been clearly established yet whether CD20 antigen density corresponds with response to Rituximab. Flow cytometry is still the most widely used technique to detect CD20 level in human serum which is expensive, time consuming and does not reveal any details of interaction between the molecules. We have developed a new innovative biosensor based novel technique to study real time interaction of CD20 antigens with Rituximab using QCM Piezo-immunosensor. This quantitative label free peptide based assay can be used to characterize cell surface antigen, to study antigen- antibody interactions and obtain understanding of mechanisms of resistance to therapy. Method: The immobilization of Raji cells on the QCM gold electrode surface using RGD tripeptide was electrochemically confirmed (Figure 1). The real-time processes of attachment of Raji cells on the gold electrode and the subsequent binding of Rituximab to the cells were studied using QCM biosensor. The interaction between Rituximab and Raji cells led to the increased resonant frequency shifts (df0) in the studied antibody concentration range from 5 to 250 μg mL-1 following the Langmuir adsorption model (Figure 2). From these observations, the apparent binding constant between a single-layer of Rituximab and Raji cells was calculated to be 1.6×106 M-1 (Figure 3). Control experiments using other therapeutic antibodies (i.e., Trastuzumab and Bevacizumab) and different cells (i.e., T cells and endothelial cells) proved very specific interaction between Rituximab and CD20 antigens on B cells. Calcium and Manganese ions were added to the cell culture and corresponding responses by QCM were monitored. Results: CD20 binding with Rituximab was very specific. This binding decreased the electrochemical activity and stability of the cells, supporting the cell lysis mechanisms of action of Rituximab. We have shown a systematic approach for using QCM technique to quantify the apparent binding constant between Raji cells and Rituximab which can reveal CD20 antigen density. Moreover, increased QCM responses were found in the presence of Ca2+ ions and high concentration Mn2+ ions, supporting the function of CD20 as a calcium ion channel. Microscopic inspection proved that increased Ca2+ ions could promote the Rituximab binding and cell lysis induced by Rituximab, which was not seen with Manganese. Conclusion: CD20 antigen density and interactions of CD20 antigens with respective monoclonal antibodies will help physicians to determine the clinical efficacy and resistance mechanisms to targeted antibodies like Rituximab and Ofatumumab. For the first time, we have established a low cost, highly sensitive, fast, synthetic, QCM assay which could be used as a basis for developing a new generation of affinity-based Immunosensor assays. This real time capability of QCM and its simplicity of operation are highly suitable for multipurpose studies on living cells including cell immobilization, cytotoxicity of drugs, and the cell action mechanisms. Figure 1 Figure 1. Figure 2 Figure 2. Figure 3 Figure 3. Disclosures No relevant conflicts of interest to declare.

Abstract 4319 Background: CBs are highly variable at diagnosis and during the course of IT in AML patients. Assessing response to IT carries a huge implication on the prognosis of individual patient with AML. Our study investigates whether late clearance of CBs during IT using standard cytarabine + anthracycline regimen is associated with refractory phenotype. Methods: We retrospectively reviewed the chart of 83 AML patients (43 males, 40 females, mean age 61.7) who received standard cytarabine and anthracycline regimen during induction between January, 2000-January, 2011 at William Beaumont Health System. Data collected include complete blood count with blast count during course of induction, and bone marrow response. AML is considered refractory if morphological evaluation, flow cytometry or cytogenetic study was positive in the first bone marrow post induction. Response to IT was assessed according to Cancer and Leukemia Group B (CALGB) criteria as complete remission versus residual leukemia or treatment failure (failing to achieve complete remission). Results: We noted that 57 of 83 patients (68.7%) showed CBs at the time of diagnosis. During the IT, CBs clearance occurred within 7 days (early clearance) in 38 of these 57 patients. The remaining 19 patients had CBs persistent more than 7 days (delayed clearance). The frequency of bone marrow residual disease at count recovery post IT was significant higher in patients with late clearance and those with early clearance (84% vs 42%, p=0.0015). Further analysis of data showed the frequency of bone marrow residual disease was not significantly different between patients with no CBs at the diagnosis and those with early clearance of CBs (38% vs 42%, p=0.8). Conclusion: Adult AML patients with persistent CBs >7 days during IT with standard induction cytarabine and anthracycline regimen are more likely to have induction failure. CBs clearance can be used as an early assessment of response to the IT. Disclosures: No relevant conflicts of interest to declare.

Abstract 3148 Background: VTEs are common complications in association with IT which may cause additional morbidity and mortality in AML patients. However, treating patients with AML is challenging because of the cytopenias due to chemotherapy and the high risk for bleeding during IT. This study investigates frequency, risk factors, and safety of using anticoagulation (AC) therapy for VTEs during IT. Method: We retrospectively reviewed the charts of AML patients who received IT between January, 2000-January, 2011 at William Beaumont Health Systems. Exclusion criteria included a documented personal history of inherited thrombophilia. Data retrieved included the following: patient characteristics, leukemia subtype, cytogenetic risk, location of the VTEs, FLT3 mutations, IT regimen used (cytarabine and anthracycline regimens or hypomethylating agents), AC therapy, bleeding complications, mortality related to AC therapy. All patients who received AC were initially treated with regular intravenous unfractionated heparin or subcutaneous low molecular weight heparin. Patients were subsequently started on oral warfarin during the first 10 days of the initial treatment with a targeted INR of 2.0–3.0. Results: We found 48 of 363 (13.2%) AML patients developed VTEs during IT. Of those patients, 56.3 % were female. The VTEs occurred most frequently in upper extremities (58%) and were catheter-related. Other locations for VTEs included lower extremities (21%), pulmonary embolism (15%), and mesenteric or portal veins (6%). We note that 41 patients (87%) received AC therapy. Of these, three patients (7.3%) had bleeding complications and no AC therapy-related deaths were observed. When the three cytogenetic risk groups were compared, there was no difference in the incidence of VTEs (good vs intermediate vs poor). Patients with FLT 3 mutations, however, had a significant higher incidence of VTEs when compared to patients without FLT3 mutations (55.3% vs 12% p Conclusions: We found that 13% of AML patients developed VTEs during IT, most commonly in upper extremities and were catheter-related. The risk for VTEs was markedly increased in patients with FLT3 mutations. Furthermore, using a cytarabine + anthracycline regimens carried a higher risk for VTEs when compared to regimens using a hypomethylating agents. Finally, using AC therapy during IT is relatively safe and is associated with low risk of bleeding complications. Disclosures: No relevant conflicts of interest to declare.

Abstract 2087 Background: During IT, AML patients may develop PI due to infection, leukostasis, pneumonitis, drug reaction or even acute respiratory distress syndrome. The risk association and the clinical outcome of such PI are poorly characterized in the literature. This study investigates the frequency, radiologic patterns, and outcome of PI during the IT of AML patients. Methods: We retrospectively reviewed 363 cases of AML patients who received IT either cytarabine and anthracycline regimens, or hypomethylating agents between January, 2000-January, 2011 at William Beaumont Health System. Of 363 patients, 120 developed PI during IT, those patients were divided into 2 groups based on distribution of the infiltrate presenting whether localized or diffuse infiltrate. Distribution of the infiltrate was evaluated by dividing the thorax vertically in the midline, then horizontally by two lines originating above and below the hilus resulting in six areas. Localized infiltrate was defined as involvement of 1–3 areas, and diffuse infiltrate was defined as >3 areas were involved. Detected by either Bronchioalveolar lavage culture or sputum culture revealing a pathogen other than coagulase-negative staphylococci or corynebacteria was considered as pathogenic microorganisms. Treatment end points were defined as resolve or persistence of the infiltrate or death. Data on pts characteristics, leukemia subtype, cytogenetic risk, microorganism type, white blood cell count (WBC) at diagnosis, neutrophils count at the time of the infiltrate reported, response to antibiotic and/or antifungal therapy, using respiratory support, mortality rate, were retrieved from the records. Results: Our study involved 120 patients. Of these, 33% developed PI during their IT. This population was 53.3 % female, median age 66 years (range 23–93). We noted that 63 patients (52.5%) had localized infiltrate and 57 patients (47.5%) had diffuse infiltrate. Of the 120 patients, 46 (39.3%) had pathogenic microorganisms. These microorganisms were found to be 50% gram positive, 32% gram negative, 10.8% fungal, and 4.3% anaerobic. All 120 patients received two broad-spectrum antibiotics and/or an antifungal. Of the total number of patients, 58 (48.7%) required intubation and ventilatory support. The repeat computed tomography at the end of the hospital stay (after the treatment) showed resolution of the infiltrate in 67 patients (55.8%). During our study, 46 patients died from PI (38.3 %). Further analysis of the data showed patients with localized PI (when compared to patients with diffuse infiltrate) were more likely to have positive pathogenic microorganisms (68.3% vs 8.8%, p Patients with diffuse infiltrate (when compared to patients with localized infiltrate) were more like to require intubation (78.9% vs 21%, p 100 Bil/L) at diagnosis (54.4% vs 0%, p Conclusions: During IT about one third of the AML patients developed PI. The radiological patterns of PI showed specific etiological and prognostic associations, may guide the clinical decision making processes. Diffuse PI is an unfavorable characteristic with overall dismal outcome. Disclosures: No relevant conflicts of interest to declare.