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Background: Patients ≥55 years of age with rel/ref AML who have failed to achieve complete remission (CR) after standard induction & salvage therapies do not routinely undergo allogeneic hematopoietic cell transplantation (HCT) due to inability to receive myeloablative conditioning and lack of efficacy. With the advent of recently approved targeted therapies (e.g. venetoclax, IDH inhibitors) more patients achieve CR, however durable responses in heavily pre-treated patient populations remain unsatisfactory with very few patients being transplanted. The SIERRA (Study of Iomab-B in Elderly Relapsed or Refractory AML) trial is a prospective, randomized, phase 3 trial designed to address this unmet need. We present the preliminary analysis of the first 50% of patients and analyze the proportion of patients who fail standard chemo and targeted therapies that can then successfully undergo HCT with Iomab-B-based conditioning. Study continues to enroll (N=150), primary end-point durable CR of ≥180 days. Methods: Eligible patients are ≥ 55 years with rel/ref AML (≥5% blasts), adequate organ function, and related/unrelated 8/8 HLA-matched donors. Patients are randomized (1:1) to receive Iomab-B followed 12-14 days later by reduced intensity conditioning (fludarabine(FLU)/TBI) and HCT, or to conventional care (CC). CC patients may receive investigator's choice of salvage therapy, including newly approved targeted agents such as venetoclax, IDH Inhibitors and may proceed to standard HCT if they achieve CR. If patients do not achieve CR, the study allows cross-over (CO) to Iomab-B with HCT. Results: Preliminary data are available from the first 75 patients enrolled on the SIERRA trial. Median age of 64 years (range: 55-77). All patients had active measurable disease (Table 1). Patients in this trial were heavily pretreated with 85% failing ≥2 induction therapies and 33% failing targeted therapies. Molecular and cytogenetics was 68% adverse risk. (NCCN, v1.2018) Following therapeutic dose of Iomab-B as a single agent, there was significant reduction of circulating blasts by day 3 (99%, p<0.0001), and peripheral blasts became undetectable by day 8 prior to FLU. All patients transplanted on the Iomab-B arm with data available showed median days to engraftment of ANC at 14 (range: 9-22) and platelets at 16 (range: 4-30) (Table 1). After randomization, 82% (31/38) patients in the CC arm failed salvage therapy and did not proceed to standard HCT. Significantly, 32% (12/38) of these patients received targeted therapy. 73% (8/11) of the patients receiving venetoclax with HMA or cytarabine did not adequately respond and did not proceed to standard HCT, 45% (5/11) crossed over to Iomab-B and received HCT. Following standard chemotherapies, 85% (22/26) were evaluated for CO. In total, 63% (19/30) received Iomab-B and HCT. The most common reason preventing crossover was disease progression. All crossover (Iomab-B) patients showed similar engraftment (Table 1). CC patients showed increased incidence of febrile neutropenia with grade 3 prior to CO evaluation or HCT, compared to Iomab-B patients prior to HCT (CC: 34%, Iomab-B: 8%). Iomab-B administration was generally well-tolerated with no grade 4 and 1 grade 3 infusion reaction. There were no Iomab-B-related deaths or 100 day non-relapse transplant related mortality deaths in patients on the Iomab-B arm (Table 1). Conclusion: 100% of the patients receiving HCT on the Iomab-B arm engrafted, despite a median of 29% BM blasts pre-Iomab-B. 82% of the patients on the CC arm failed to be eligible for standard of care transplant, including a high percentage of those receiving targeted therapies. On the CC arm, 63% of eligible patients crossed over to Iomab-B/HCT with robust engraftment despite a median of 35% BM blasts pre-Iomab-B. The incidence of grade 3 febrile neutropenia was higher in patients treated on the conventional care arm with salvage therapy vs. those treated on the Iomab-B arm prior to HCT. In conclusion, despite advanced age, active disease and heavily pre-treated patients, 68% (50/74) of all patients enrolled in the SIERRA trial were able to undergo HCT after reinduction and targeted conditioning with Iomab-B. These results show significant improvements in the current rates of transplantation in this patient population. This SIERRA trial is currently enrolling. For full study details see www.sierratrial.com or clinicaltrials.gov (NCT02665065). Disclosures Gyurkocza: Actinium Pharmaceuticals: Research Funding. Nath:Astellas: Consultancy; Actinium: Consultancy; Daiichi Sankyo: Consultancy. Stiff:Amgen: Research Funding; Gamida-Cell: Research Funding; Incyte: Research Funding; Unum: Research Funding; Cellectar: Research Funding; Gilead/Kite Pharma: Consultancy, Honoraria, Research Funding. Tomlinson:Actinium Pharmaceuticals, Inc: Other: Travel Support. Abhyankar:Incyte: Speakers Bureau; Therakos: Other: Consulting, Speakers Bureau. Hari:AbbVie: Consultancy, Honoraria; Cell Vault: Equity Ownership; Sanofi: Honoraria, Research Funding; Spectrum: Consultancy, Research Funding; Amgen: Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Research Funding; Janssen: Consultancy, Honoraria; Kite: Consultancy, Honoraria. Al-Kadhimi:Seattle Genetics: Other: Stocks; Celldex Biotech: Other: Stocks. Foran:Agios: Honoraria, Research Funding. Orozco:Actinium Pharmaceuticals: Research Funding. Van Besien:Miltenyi Biotec: Research Funding. Sabloff:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astellas Pharma Canada: Honoraria, Membership on an entity's Board of Directors or advisory committees; ASTX: Membership on an entity's Board of Directors or advisory committees, Research Funding; Jazz Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees; Actinium Pharmaceuticals, Inc: Membership on an entity's Board of Directors or advisory committees; Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer Canada: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi Canada: Research Funding. Kebriaei:Pfizer: Honoraria; Kite: Honoraria; Jazz: Consultancy; Amgen: Research Funding; Pfizer: Honoraria; Kite: Honoraria; Jazz: Consultancy; Amgen: Research Funding. Levy:Takeda (Millennium Pharmaceuticals): Consultancy. Lazarus:Adaptive Biotechnologies: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria, Speakers Bureau; Actinium Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Teva Pharmaceuticals: Speakers Bureau; Biosight: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Consultancy, Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau; AstraZeneca: Honoraria, Speakers Bureau; Bristol Myers Squibb: Honoraria, Speakers Bureau; Pluristem Therapeutics, Inc: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; CSL Behring: Consultancy; Genentech: Speakers Bureau. Giralt:Novartis: Consultancy; Actinium: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Jazz Pharmaceuticals: Consultancy; Amgen: Consultancy, Research Funding; Kite: Consultancy; Miltenyi: Research Funding; Takeda: Consultancy, Research Funding; Johnson & Johnson: Consultancy, Research Funding; Spectrum Pharmaceuticals: Consultancy. Berger:Actinium Pharmaceuticals, Inc: Employment, Equity Ownership. Reddy:Actinium Pharmaceuticals: Employment. Pagel:Pharmacyclics: Consultancy; AstraZeneca: Consultancy; Gilead Sciences: Consultancy.

Abstract BACKGROUND Treatment options and prognosis are limited for patients with high grade glioma (pwHGG), underscoring the importance of patient and caregiver understanding to prioritize goals of care and quality of life (QOL). Although addressed by multiple providers, patients and caregivers may experience discordance in understanding the prognosis. This may be related to patient/caregiver perception, cognitive decline as a result of the tumor and/or treatment, or failure by the clinician to clearly articulate this information under emotional circumstances. AIMS: To evaluate the longitudinal perception of prognosis of patients compared to their caregivers and their providers during the adjuvant treatment of newly diagnosed HGG. METHODS After IRB approval, 16 pwHGG, their caregivers and their providers reported an overall survival estimate at each monthly visit during adjuvant treatment, as part of a larger survey. Options included “weeks,” “weeks to several months,” “several months to years,” “indefinite number of years”, or “I do not wish to answer.” RESULTS Seven of the sixteen patient/caregiver clusters have completed the appropriate duration of the study with the remaining completing in November. The perception of the patient differs from the caregiver at almost each visit. Regardless of the counseling provided by provider, the perception of both tends to change at each visit and can vary from dismal to overtly optimistic. There does not appear to be discrepancy between the neuro-oncology and palliative care provider’s perception of prognosis. CONCLUSION Newly diagnosed pwHGG and caregivers vary in their perception of prognosis, deviating not only from each other but also differing at each visit throughout the course of their illness. The providers’ perception appeared to remain consistent but often varied from that of the patient and caregiver. Providers need to be aware that prognostic understanding appears to fluctuate throughout the course of illness and cannot be clarified via a single discussion.

Abstract BACKGROUND Early involvement of palliative care (PC) in patients with metastatic cancer has been associated with improved quality of life (QOL). Patients with high grade glioma (pwHGG) and their caregivers have unique needs such that similar results are anticipated in this population but cannot be extrapolated. Recognizing that pwHGG often require a caregiver early in the course of disease, this patient population also experiences significant personal and caregiver distress that has been given limited attention and resources. AIM: To assess the feasibility of implementation of a novel patient reported outcomes (PRO) quality of life (QOL) tool administered by smart device in routine office visit (OV) and early integration of palliative care (PC) for pwHGG and their caregivers to improve QOL for both. DESIGN: Prospective, single-center cluster-randomized pilot conducted for 6 months during completion of adjuvant therapy for newly diagnosed high grade glioma. After informed consent was obtained, 15 pwHGG and their caregivers were randomized to: routine OV with basic QOL survey; OV with PROQOL; or PC consultation, in addition to OV with PROQOL. RESULTS Two elderly patients with declining performance status transitioned to hospice after initial visit, and one moved out of state prior to adjuvant visits. Thus far 5/15 patients/caregivers have successfully completed the pilot with the 6 remaining participants due to complete in November 2019. DISCUSSION The PROQOL appears to be easily integrated into OV without significant patient, caregiver, or provider burden. Providers confirmed utility in prioritizing symptoms and concerns. Thus far, it appears that patients (and caregivers) appeared to benefit from the PROQOL and PC support as evidenced by longitudinal improvement in QOL scores over the control group. CONCLUSIONS A unique PROQOL tool and early PC can be easily integrated into practice, and may improve the QOL of pwHGG and their caregivers.

Abstract Both family caregivers and providers report numerous challenges to providing care for of adults with Alzheimer’s disease and related dementias (AD/RD). Many of these challenges stem from ineffective communication and coordination within the health and support service networks, including: (1) communication challenges posed by AD/RD patients; (2) communication barriers between caregivers and providers; and (3) communication barriers among providers across institutions. Caregivers increasingly rely on technology to fill gaps in their knowledge, identify social support, and learn how to execute more complex care demands. While technology has been suggested as an effective strategy for improving the quality of AD/RD care and support caregivers, the role that public policy and research can and should play in advancing the goal of such tech-based solutions is still emerging. This is especially true in respect to how technology can strengthen care networks for patients and caregivers who are racial/ethnic minorities and/or living in rural communities. This presentation will identify the role that past legislation (e.g. the Affordable Care Act, HITECH, Medicaid) has played, as well as the role that recent and proposed legislation (e.g. RAISE Caregiver Act, CARE Act, 21st Century Cures Act, BOLD Infrastructure for Alzheimer’s Act, Older American’s Act reauthorization) should play in strengthening the health, support networks that caregivers interact with to provide ongoing care. This presentation will also summarize the current state of research on caregiver technologies and discusses how future research and policy initiatives can promote the translation of tech-based interventions into everyday care settings.

AbstractAuthentic inclusion and engagement of behavioral health patients in their care delivery and in the process of scientific discovery are often challenged in the health care system. Consequently, there is a growing need to engage with and better serve the needs of behavioral health patients, particularly by leveraging health information technologies. In this work, we present rationale and strategies for improving patient engagement in this population in research and clinical care. First, we describe the potential for creating meaningful patient–investigator partnerships in behavioral health research to allow for cocreation of knowledge with patients. Second, in the context of behavioral health services, we explore the utility of sharing clinical notes to promote patients' agency in care delivery. Both lines of inquiry are centered in a Learning Health System model for behavioral health, where patients are agents in enhancing the therapeutic alliance and advancing the process of knowledge generation. Recommendations include genuinely democratizing the health care system and biomedical research enterprise through patient-centered information technologies such as patient portals. In research and technology development, we recommend seeking and tailoring behavioral health patients' involvement to their abilities, promoting patient input in data analysis plans, evaluating research and informatics initiatives for patients and clinicians, and sharing success and research findings with patients. In clinical practice, we recommend encouraging patients to read behavioral health notes on portals, engaging in proactive communication regarding note content, assessing outcomes including stress and anxiety in response to note content, and working with technology providers to support note-sharing governance and deployment.

Abstract Introduction Acute graft-versus-host disease (aGVHD) is a significant cause of mortality post allogeneic stem cell transplantation (SCT). First line therapy is corticosteroid based for patients with aGVHD ≥grade (Gd) II. Steroid refractory (SR) aGVHD is associated with a dismal prognosis. Although experimental therapeutics is an unmet need, there is no recent prospective real world data to establish a benchmark for outcomes of best available therapy. We undertook a prospective observational multi-centre international clinical trial of outcomes of second line therapy of steroid refractory aGVHD. The aim was to measure recently defined endpoints including Day 28 (D28) overall response rate (ORR), and 6 month freedom from treatment failure (6mFFTF; defined as a patient (pt) being alive, without relapse of underlying disease or addition of new systemic therapy for aGVHD, prior to the development of chronic(c) GVHD. Methods Data was collected prospectively in a longitudinal observational study in patients starting second line therapy for SR aGVHD. Twelve UK and 2 US sites participated. Adult pts with Gd II-IV aGVHD refractory to corticosteroids were enrolled within 5 days of starting second line therapy. Modified Glucksberg criteria were used to grade aGVHD. Expert panel consensus recommendations (Martin et al 2009) were used for complete response (CR), very good partial response (VGPR), partial response (PR), stable disease (SD) and progressive disease (PD). Kaplan-Meier survival curves and log rank tests for comparison were done on Prism7. Results Between 2014-2018, 64pts were enrolled; 4pts were excluded due to incomplete data. Baseline characteristics of the cohort are outlined in Table 1. GVHD prophylaxis varied according to centre. Forty-seven percent had T depletion; 32% ATG and 25% Alemtuzumab. GVHD was donor lymphocyte infusion (DLI) induced in 7%. At start of second line therapy,5% had Gd I, 27% Gd II and 68% Gd III-IV aGVHD. All patients had received corticosteroids at a minimum dose of 1mg/kg. Second line therapies varied, 60% received ECP and 40% non-ECP therapy including anti-TNF-alpha antibodies (20%), mycophenolate mofetil (MMF) (8%), mesenchymal stem cells (4%) and 'other' (8%). The cumulative incidence of 6mFFTF was 32% (n=19), with 68% (n=41) failing to meet the 6mFFTF endpoint. The causes of failure were, addition of third line therapy in 40% (n=24), relapse 8%(n=5), cGVHD 7% (n=4) and death 13% (n=8). The 6m incidence of death was 45% (n=27); death due to GVHD 30%, infection 8% and relapse 7%. D28 responses were: 56% ORR (8% CR, 28% VGPR, 20% PR), 13% SD, 18% PD and 13% died before D28. Using Kaplan-Meier analysis, median OS was 7.3m with a median follow up of 1 year. The overall cumulative incidence of death was 63% (n=38); GVHD was the leading cause of death 40%, infection 8% and relapse 8%. D28 ORR was associated with a significantly improved median OS not reached versus (vs) 5.2m (p=0.03) in pts who had SD or PD at D28. In pts that achieved 6mFFTF, median survival beyond 6m was not yet reached vs median survival of 3.9m in those that did not achieve 6mFFTF (p=0.0004). The trend was for a longer median OS of 8.2m in the ECP arm vs 5.3m in non ECP (p=0.79). GVHD Gd at start of second line therapy was associated with a longer median survival, not reached in Gd II cohort vs 5.7m in Gd III-IV cohort (p=0.25). Discussion Our multi-centre prospective study illustrates 'real-life' data of clinical outcomes in pts starting second line therapy for SR aGVHD. Median survival from start of second line therapy was 7.3m with a high mortality rate of 63%. D28 ORR was 56% but only 32% met the composite 6mFFTF endpoint, although both outcomes predicted survival. The leading cause for failure of 6mFFTF was starting third line therapy which may be subject to clinician bias, however the 6m mortality was 45%, thus pts went on to die after failing for another cause. This data can be used as a contemporary data while planning studies of experimental intervention vs. best available therapy. Disclosures Radia: Mallinckrodt: Research Funding. Alfred:Mallinckrodt: Speakers Bureau. Dignan:Mallinckrodt: Research Funding, Speakers Bureau. Jagasia:Incyte Corporation: Membership on an entity's Board of Directors or advisory committees.

Abstract Relapse of malignancy and lethal graft versus host disease (GVHD) are the principal causes of failure of allogeneic hematopoietic cell transplant (HCT). Recently we have shown that at seven days after HCT an algorithm using two serum biomarkers (ST2 and REG3α) can predict severe GVHD (Hartwell et al. JCI Insight 2017). We determined whether serial testing (in the first month following HCT) of patients with low probability biomarkers would improve the predictive accuracy of the algorithm and identify patients with different risks of relapse and lethal GVHD. Patients who received an HCT at 18 centers in the Mount Sinai Acute GVHD International Consortium (MAGIC) for hematologic malignancy and who supplied three blood samples were divided into a training set and validation set with equal numbers of lethal GVHD events, which was defined as death from GVHD or infection during treatment for GVHD. Patients in the training set (n=702) underwent HCT from January 1, 2006 until June 30, 2015, whereas patients in the validation set (n=906) underwent HCT from July 1, 2015 to May 1, 2017. Serum samples were analyzed using the previously published algorithm of two biomarkers up to three times (day 7, day 14, day 28 or GVHD onset, if onset occurred within the first 28 days). The algorithm generates a predicted probability of lethal GVHD between 0 and 1 for each patient. Patients were categorized as either low probability (LP) or high probability (HP) for lethal GVHD. HP thresholds of 0.20 and 0.16 were used to classify patients with and without GVHD symptoms, respectively (once categorized as HP, patients remained in that category and were not retested). All results were similar between training and validation sets, and we present here the validation set results. Serial testing identified 28% of patients as HP with a three-fold greater cumulative incidence of lethal GVHD at one year (13% vs 4%, p<0.001, Figure 1). Relapse rates were the same in both probability groups, and thus LP patients experienced significantly better relapse free survival (RFS) (69% vs 53%, p<0.001). As expected, significantly fewer LP patients experienced severe GVHD at onset (as measured by Minnesota risk), maximum grade III/IV GVHD, or steroid resistant GVHD by day 180 after HCT (Figure 2, p<0.001 for all three parameters). To measure the accuracy of prediction, at each timepoint we calculated the area under the curve (AUC) of receiver operating characteristic curves; the AUC increased significantly with each subsequent evaluation, from 0.59 at one timepoint (dotted line) to 0.74 at the third timepoint (solid line) (p<0.001), with a final sensitivity of 65% and specificity of 74% (Figure 3A). Early development of GVHD (by day 28) is a risk factor for lethal GVHD. Therefore, we next plotted RFS (dashed line), relapse (solid line), and lethal GVHD (dotted line) rates in patients who developed GVHD by day 28. 25% of patients with GVHD were categorized as HP and had a cumulative incidence of lethal GVHD more than four times higher (28%) than that of relapse (6%); however the risks were reversed for the 75% of patients who were LP, where relapse (15%) occurred twice as often as lethal GVHD (7%) (Figure 3B). In patients who did not develop GVHD in the first month, this reversal of risks was even more dramatic. Approximately half (53%) of the entire validation cohort did not develop GVHD by day 28 and was LP at all three evaluations. These patients had an exceptionally low risk of lethal GVHD and thus they relapsed (25%) much more often than they died from GVHD (3%). When malignancies were classified according to risk for relapse by the disease risk index (DRI) (Figure 3C), the probability of relapse was three fold higher than lethal GVHD in malignancies with a low DRI (12%), six fold higher for intermediate DRI (20%), and eleven fold higher for high/very high DRI (33%). We conclude that a serial monitoring strategy using GVHD biomarkers for one month after HCT is able to identify two groups of patients with very different risks of lethal GVHD and relapse. For these patients, the intensity of immunosuppression after day 28 could be tailored according to the probabilities of developing lethal GVHD and relapse in the context of clinical trials. Disclosures Aziz: Doris Duke Charitable Foundation: Research Funding. Ayuk:Therakos (Mallinckrodt): Honoraria; Novartis: Honoraria; Celgene: Consultancy; Gilead: Consultancy. Chen:REGiMMUNE: Consultancy; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees; Magenta Therapeutics: Consultancy; Takeda Pharmaceuticals: Consultancy. Merli:Neovii Biotech: Honoraria; AMGEN: Honoraria. Roesler:Sanofi: Other: Travel, Accommodations, Expenses; Amgen: Equity Ownership; Jazz Pharmaceuticals: Other: Travel, Accommodations, Expenses; Immunomedics: Equity Ownership; Biogen: Equity Ownership; Merck: Consultancy; Pfizer: Consultancy. Kitko:Novartis: Consultancy, Honoraria; Mallinckrodt: Honoraria, Other: Travel, Accommodations, Expenses. Qayed:Novartis: Consultancy. Wölfl:Bristol-myers Squibb: Equity Ownership; Novartis: Equity Ownership; Taheda: Equity Ownership; Juno: Equity Ownership; Neovii: Other: Travel, Accommodations, Expenses. Mielke:Celgene: Speakers Bureau; DGHO: Speakers Bureau; EHA: Speakers Bureau; Kiadis Pharma: Speakers Bureau; Miltenyi: Speakers Bureau. Wudhikarn:Takeda Oncology: Other: Travel, Accommodations, Expenses. Nakamura:Celgene: Honoraria; Molmed: Honoraria; Merck: Consultancy; Pharmacyclics: Consultancy; Atara: Consultancy; Jazz Pharmaceuticals: Consultancy. Pulsipher:CSL Behring: Consultancy; Novartis: Consultancy, Honoraria, Speakers Bureau; Adaptive Biotech: Consultancy, Research Funding; Amgen: Honoraria. Reshef:Pfizer: Consultancy; Atara Biotherapeutics: Consultancy; Kite Pharma: Consultancy; Takeda Pharmaceuticals: Consultancy; Bristol-Myers Squibb: Consultancy; Incyte: Consultancy. Levine:Therakos: Consultancy; Novartis: Consultancy; Bluebird: Consultancy; Incyte: Consultancy; Kamada: Research Funding; Viracor: Patents & Royalties. Ferrara:Incyte: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; Xenikos: Consultancy, Other: Travel, Accommodations, Expenses; Kamada: Consultancy, Research Funding; Viracor: Consultancy, Patents & Royalties.

Abstract Background: Patients ≥55 years of age with active, relapsed or refractory acute myeloid leukemia (R/R AML) who have failed standard induction therapies most often receive salvage therapy with a wide variety of agents, but very few achieve remission. These patients do not routinely undergo allogeneic hematopoietic cell transplantation (HCT) due to lack of efficacy using a standard HCT approach. The SIERRA trial is a prospective, randomized, phase 3, open-label, ongoing multicenter trial designed to address this significant unmet need in R/R AML. This trial compares Iomab-B, an 131I-radiolabeled anti-CD45 antibody as targeted conditioning prior to HCT against standard conventional care therapies with an accrual goal of 150 patients. We have performed a preliminary safety analysis, validating the initial feasibility of this multi-center trial. Methods: Eligible patients are ≥ 55 years of age with active, R/R AML, adequate organ function, and related/unrelated matched donor. Patients are randomized (1:1 ratio) to receive dosimetry directed Iomab-B followed 12 days later by HCT with fludarabine 30 mg/m2 x 3 days and 2 Gy of total body irradiation as transplant conditioning, or to a Conventional Care (CC) arm. Patients randomized to CC, may receive investigator's choice of salvage induction chemotherapy including approved targeted agents as well as Venetoclax (in combination with a hypomethylating agent) and proceed to standard HCT if they achieve complete remission (CR). If patients do not achieve CR, the study allows optional cross-over to the Iomab-B arm, evaluated between days 28-42 after CC therapy. The primary efficacy endpoint for the study is durable complete remission (dCR) of 6 months. The secondary efficacy objective is to evaluate overall survival at 1 year. Results: Forty patients have been enrolled to date and data are available for 38 patients (19 = Iomab-B, 19 = CC) as of July 5th, 2018. The median age was 63 years (range: 55-76). All patients had active disease at the time of enrollment with median bone marrow (BM) blasts of 30% in the Iomab-B arm and 47% in the crossover arm prior to receiving Iomab-B (Table 1). Of the patients in the CC arm, 88% did not achieve a CR and 65% of those crossed-over to receive Iomab-B. The most common reason preventing crossover was declining performance status. Time to HCT was not increased in the crossover patients receiving Iomab-B compared to those that underwent a standard of care transplant after achieving CR (median 65 vs 75 days), while the Iomab-B arm patients were transplanted at a median of 27 days after randomization. Iomab-B therapy was well-tolerated with no grade 3 or 4 infusion-related reactions reported. The median activity of Iomab-B was 626 mCi (range: 397-1027). All patients randomized to Iomab-B (N=13) engrafted, with median days to engraftment of ANC at 13 (range: 9-22) and platelets at 17 (range: 13-26). All patients who received Iomab-B after crossover (N=9) also engrafted with time to engraftment similar to patients initially randomized to the Iomab-B arm (Table 1). Donor chimerism (≥95%), within 100 days after HCT, was found in 9 of 10 patients in the Iomab-B arm and 8 of 9 patients in those that crossed over to receive Iomab-B, with two patient exceptions having mixed donor chimerism at day 28. A preliminary safety analysis for all randomized patients on either study arm showed the most frequent non-hematologic adverse events ≥ grade 3 occurring in >10% patients were febrile neutropenia (34.2%), stomatitis (15.8%), malnutrition (13.2%), epistaxis, sepsis, hypotension, hypobilirubinemia and fatigue (all 10.5%). There were no Iomab-B-related deaths. Interpretation: Preliminary safety analysis demonstrates the feasibility of delivering targeted conditioning with Iomab- B for HCT in R/R AML patients who have active disease and a high BM blast burden (median: ≥ 30%) prior to transplantation. All patients who received Iomab-B, including those crossed over after failing to achieve CR on CC salvage therapy, engrafted ANC within 13 days, despite active disease prior to transplant. In addition, the time to HCT from randomization was not increased in patients receiving Iomab-B after cross-over compared to those who underwent standard of care HCT after achieving CR on the CC arm. This study is currently enrolling and for full study details see www.sierratrial.com or clinicaltrials.gov (NCT02665065). Disclosures Tomlinson: Foundation Medicine: Consultancy. Foran:Xencor, Inc.: Research Funding; Agios: Research Funding. Chen:Bellicum Pharmaceuticals: Research Funding. Levy:Takeda (Millennium Pharmaceuticals, Inc.): Consultancy. Lazarus:Pluristem Ltd.: Consultancy. Berger:Actinium Pharmaceuticals: Employment, Equity Ownership. Reddy:Actinium Pharmaceuticals: Employment, Equity Ownership; Pharmacyclics: Employment. Pagel:Pharmacyclics, an AbbVie Company: Consultancy; Gilead: Consultancy.

Abstract Abstract 1409 MYC is among the most prolific oncogenes in cancer, yet pharmacologic strategies to modulate the function of the c-Myc oncoprotein do not exist. Toward this objective, we have undertaken to target c-Myc transcription by interfering with chromatin-dependent signal transduction to RNA polymerase, specifically by inhibiting the acetyl-lysine recognition domains (bromodomains) of putative co-activator proteins implicated in transcriptional initiation and elongation. Using a selective small-molecule bromodomain inhibitor, JQ1, we identify BET bromodomain-containing proteins as transcriptional regulatory factors for c-Myc. BET inhibition with JQ1 rapidly downregulates c-Myc transcription, followed by depletion of chromatin-bound c-Myc and genome-wide downregulation of Myc-dependent target genes. In translational model systems of multiple myeloma and Burkitt's lymphoma, both canonical MYC -dependent hematologic malignancies, JQ1 treatment produces a potent antiproliferative effect associated with cell cycle arrest. In multiple myeloma, adhesion to bone marrow stroma is associated with upregulation of BRD4, a BET bromomdomain coactivator protein. Inhibition of Myc function with JQ1 leads to impaired adhesion to stroma and cellular senescence, a classical Myc-specific phenotype. Mechanistically, JQ1 treatment depletes BRD4 from IgH enhancers, leading to prompt and robust downregulation of MYC transcription. In vivo efficacy of JQ1 in two disseminated models of multiple myeloma and in a Burkitt's lymphoma human xenograft establishes the therapeutic rationale for BET bromodomain inhibition in these diseases. Together, these studies identify a mechanistic rationale for targeting c-Myc in human cancer, and potentially other undruggable oncogenes driven by immunoglobulin rearrangement. Note: G.C.I. and J.E.D. have made equal contributions to this research; C.S.M. and J.E.B. are jointly senior authors Disclosures: Richardson: Millennium: Advisory Board; Celgene: Advisory Board; Johnson & Johnson: Advisory Board; Novartis: Advisory Board; Bristol Myers Squibb: Advisory Board. Ghobrial:Bristol-Myers Squibb: Research Funding; Millennium: Research Funding; Noxxon:; Millennium:; Celgene:; Novartis:. Anderson:Celgene: Consultancy, Honoraria; Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Kung:Novartis Pharmaceuticals: Consultancy, Research Funding. Mitsiades:Millennium Pharmaceuticals: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Novartis Pharmaceuticals: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Merck: Consultancy, Honoraria; Kosan: Consultancy, Honoraria; Pharmion: Consultancy, Honoraria; Centocor: Consultancy, Honoraria; Amnis Therapeutics: Consultancy, Honoraria; PharmaMar:; OSI Pharmaceuticals: Research Funding; Amgen: Research Funding; AVEO Pharma: Research Funding; EMD Serono: Research Funding; Sunesis: Research Funding; Gloucester Pharmaceuticals: Research Funding; Genzyme: Research Funding; Johnson & Johnson: Research Funding. Bradner:Acetylon Pharmaceuticals: Scientific Founder; SHAPE Pharmaceuticals: Scientific Founder; Tensha Therapeutics: Scientific Founder.