Ganzel, Chezi

Abstract Introduction Nadir bone marrow biopsies (BM Bx) are routinely performed around day 14 to assess early response to AML intensive induction therapy. The presence of residual disease prompts initiation of reinduction therapy, often with another cycle of intensive chemotherapy. Whether there are characteristics of nadir BM Bx that predict for response to intensive reinduction is unknown. To evaluate this, we analyzed data from ECOG-ACRIN clinical trials in AML of intensive induction chemotherapy with nadir biopsy information available to determine predictors of outcomes after reinduction. Methods We included patients from ECOG-ACRIN E1900 (Fernandez NEJM 2009) and arm A of E2906 (Foran ASH 2015) who received induction therapy with daunorubicin and cytarabine (7+3), had residual disease (blasts ≥5% or cellularity ≥20%) at nadir BM Bx and received reinduction chemotherapy. Nadir BM Bx characteristics that were evaluated included blast percentage and cellularity as well as both absolute and relative (percentage change, e.g. 20% to 10% = -50%) differences calculated between diagnosis and nadir for each parameter. Complete remission (CR) after reinduction therapy, disease free survival (DFS) and overall survival (OS) were outcomes for all analyses. Logistic regression models were used to evaluate associations with CR, and Cox proportional hazards models were used for DFS and OS. For models evaluating changes in blast percentage or cellularity as predictors, baseline blast percentage or cellularity was included as a covariate, respectively. Results Of 1013 patients identified, 750 (74%) had a nadir biopsy, 233 (23%) had evidence of residual disease, received reinduction therapy, and were included in the primary analysis. The median age was 58 and 42% were female. Cytogenetic risk category (by ELN2017) was adverse in 31%, intermediate in 66% and favorable in 3%. The median nadir BM Bx blast was 30% (range 0 to +97%) and cellularity was 20% (0 to +100%). The median absolute difference in blast percentage between baseline and nadir BM Bx was -15% (-95% to +66%) with a median relative difference of -36% (-100% to +400%). After reinduction, 118 patients (52%) achieved a CR. Neither absolute difference in blast percentage (OR 0.99, 95%CI 0.98-1.00, p=0.20) nor relative difference (OR 1.00, 95%CI 0.99-1.00, p=0.33) predicted CR. There was similarly no association with DFS (HR = 1.00, 95%CI: 0.99-1.01, p=0.65) or OS (HR = 1.00, 95%CI 0.99-1.01, p=0.76). Blast reduction ≥50% similarly did not predict these outcomes. We also evaluated the impact of any reduction in blast percentage (responders) from baseline to nadir and again found no association with CR (OR 1.65, 95%CI 0.90-3.03, p=0.11). Similarly, there was no association with DFS (HR 0.74, 95%CI 0.51-1.09, p=0.13) or OS (HR 0.81, 95%CI 0.58-1.13, p=0.21) in responders vs nonresponders. No association with CR, DFS or OS were identified when performing the same analysis in intermediate and adverse cytogenetic subgroups. We found no association with CR when nadir cellularity was assessed as a continuous variable (OR 0.99, 95%CI 0.98-1.00, p=0.10) or by relative difference (OR 0.99, 95%CI 0.99-1.00, p=0.10). There was a trend towards association with absolute reduction in cellularity from baseline to nadir and CR (OR 0.99, 95%CI 0.98-1.00, p=0.06). No association was identified between relative difference in cellularity and DFS and OS, nor was there an association among cytogenetic risk subgroups with any outcome. Discussion In intensively treated patients with residual disease at nadir BM Bx (i.e. day 14) who received intensive reinduction, the likelihood of achieving a CR was not influenced by the magnitude of disease reduction nor the extent of disease at the time of nadir biopsy. Similarly, there were no nadir biopsy features that predicted DFS or OS after intensive reinduction therapy. Given alternative reinduction therapies such as hypomethylating agents and venetoclax are available, these results suggest that the decision to attempt a second intensive induction cycle following the unequivocal presence of residual disease should not be influenced by characteristics of the nadir BM Bx. Although patient-specific factors such as patient fitness may favor a switch to less intensive options, these results support consideration of intensive reinduction therapy in patients with residual disease at nadir biopsy, even without changes in blasts or cellularity.

Abstract Introduction Several studies reported that AML patients who remain in long-term remission after allogeneic transplant (allo-HCT) or autologous transplant (auto-HCT) have a shorter life expectancy, compared to the general population. However, little is known about the life expectancy of adult long-term survivors of AML who were treated with chemotherapy without HCT and, there have been no comparisons with survival among the general population. The current study reports on the life expectancy of AML patients who survived 3 years in complete remission (CR) after treatment without HCT, and compared this to the gender- and age-matched normal population. At 3 years in CR, the incidence of recurrence is exceedingly low (3%; Watts JM, Leuk Res 2014) minimizing the impact of relapse on the long-term survival. Methods Between 1984 and 2008, 3,012 patients, aged 15 years and older, with untreated AML entered 9 consecutive, phase II and III, ECOG-ACRIN trials (E3483, PC486, E3489, E1490, E3993, E4995, E3997, E3999, E1900). Patients in CR and relapse-free at 3 years are included in the analysis . Minimal cytogenetic information was available in the early protocols (E1490, E3483, PC486). A Kaplan-Meier plot was generated for the three groups, allo, auto and no HCT, censoring for patients alive at last contact. Univariate and multivariate cox proportional hazard regression models were generated, considering death as an event. For comparison of long-term outcomes, patients were grouped together by age and matched to a normative population mortality rate. Subjects were also grouped by gender and treatment allowing for separate analysis of these groups with the no HCT group as the main group of interest. The normative population comparator of expected deaths was derived using mortality rates from United State CDC life table data. The median year was derived by calculating the person-years for each calendar year that patients were followed. To calculate the expected deaths for each age group, person-years was calculated by tabulating the years lived in each age group for all subjects. Each year of follow-up for AML patient was counted as one person year, and the tabulated bin corresponded with their age at the time. Person-years was then multiplied by the matching mortality rate. Chi-square statistics were derived using expected and observed deaths and then summed for each gender and treatment. The final comparison was of mortality rates since diagnosis in the 3-year alive and relapse-free AML patient population vs the normative population. To produce plots of mortality from diagnosis, person-years was tabulated for every year since diagnosis by treatment. The person-years were tabulated into 2-year bins. The US life tables from the CDC were used to generate a population mortality rate from diagnosis. Results A total of 503 adult AML patients in 3 year CR with a mean age of 42.9 years (15-79) were identified; 78 underwent allo, 110 auto and 315 did not undergo transplantation. The patients in the groups differed in age (p<.001) and cytogenetics (p=.01). The multivariate model showed equivalent hazards of death to the 3 groups. Observed deaths and person-years were given by age group, gender, and treatment group and each were matched to a mortality rate from the United State CDC life table data that matched the median year of each treatment group. A chi square test for each group compared the derived expected to observed deaths. In every treatment group, patients had a shorter survival compared to their age- and gender- matched general population (p-value of 0.004 for the auto-HCT and <0.001 for both allo-HSCT and no transplant groups). Table 1, selected only for the no HCT group, demonstrates the mortality rates by age and gender. Figure 1 indicates that AML patients who have survived relapse-free for at least 3 years continue to have higher mortality rates compared to the normative population for up to 14 years. This finding is not altered even if the very small number of patients who die from late relapse (>3 years from diagnosis) are removed from the analysis (data not shown) Conclusions Patients with AML who remain in CR at 3 years, do not have a normal life expectancy, even if they do not undergo HCT. The shorter life expectancy observed following an HCT may, at least in part, be related to the prior intensive therapy or other predisposing factors (e.g. CHIP) of the leukemia, rather than the transplant procedure itself. Figure 1 Figure 1. Disclosures Luger: Syros: Honoraria; Agios: Honoraria; Daiichi Sankyo: Honoraria; Jazz Pharmaceuticals: Honoraria; Brystol Myers Squibb: Honoraria; Acceleron: Honoraria; Astellas: Honoraria; Pfizer: Honoraria; Onconova: Research Funding; Celgene: Research Funding; Biosight: Research Funding; Hoffman LaRoche: Research Funding; Kura: Research Funding. Lazarus: Bristol Myer Squibb: Membership on an entity's Board of Directors or advisory committees. Douer: Amgen: Consultancy, Speakers Bureau; Servier: Consultancy, Speakers Bureau; Adaptive: Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company, Speakers Bureau; Jazz: Consultancy. Tallman: Syros: Membership on an entity's Board of Directors or advisory committees; Kura: Membership on an entity's Board of Directors or advisory committees; Innate Pharma: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Biosight: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Jazz Pharma: Membership on an entity's Board of Directors or advisory committees; Oncolyze: Membership on an entity's Board of Directors or advisory committees; KAHR: Membership on an entity's Board of Directors or advisory committees; Orsenix: Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Rafael Pharmaceuticals: Research Funding; Glycomimetics: Research Funding; Biosight: Research Funding; Orsenix: Research Funding; Abbvie: Research Funding; NYU Grand Rounds: Honoraria; Mayo Clinic: Honoraria; UC DAVIS: Honoraria; Northwell Grand Rounds: Honoraria; NYU Grand Rounds: Honoraria; Danbury Hospital Tumor Board: Honoraria; Acute Leukemia Forum: Honoraria; Miami Leukemia Symposium: Honoraria; New Orleans Cancer Symposium: Honoraria; ASH: Honoraria; NCCN: Honoraria. Litzow: Pluristem: Research Funding; Biosight: Other: Data monitoring committee; AbbVie: Research Funding; Actinium: Research Funding; Astellas: Research Funding; Omeros: Other: Advisory Board; Jazz: Other: Advisory Board; Amgen: Research Funding.

Abstract Central nervous system (CNS) involvement in patients with newly diagnosed acute myeloid leukemia (AML) is rare, and systematic data regarding outcome are scarce. This retrospective study summarized data from 11 consecutive Eastern Cooperative Oncology Group-American College of Radiology Imaging Network (ECOG-ACRIN) clinical trials for patients with newly diagnosed AML. In all, 3240 patients with AML were analyzed, and 36 (1.11%) were found to have CNS involvement at diagnosis. The incidence of CNS disease among the 5 studies with per protocol mandatory lumbar puncture (LP) was similar to the incidence among studies in which LP was performed at the discretion of the investigator (0.86% vs 1.41%; P = .18). There was no significant difference in the rate of complete remission (CR) among patients with CNS involvement and those with other extramedullary disease (EMD) sites or those with no EMD (52.8% vs 59.3%-60%). The median overall survival (OS) for patients who were CNS positive, who had other EMD, or who had no EMD was 11.4, 11.3, and 12.7 months, respectively. There was no difference in OS among patients with CNS involvement, those with other EMD (hazard ratio [HR], 0.96; adjusted P = .84), and those with no EMD (HR, 1.19; adjusted P = .44). In conclusion, the reported incidence of CNS involvement in patients with newly diagnosed AML is low (1.1%), irrespective of whether an LP is mandatory or not. The presence of CNS disease at diagnosis in and of itself does not seem to portend a poor prognosis for achieving an initial CR or for OS.

Summary Late relapse [>3 years from complete remission (CR)] in acute lymphoblastic leukaemia (ALL), is unusual. Data from the MRC UKALLXII/ECOG E2993 trial are presented to evaluate the incidence and characteristics of late relapse in adult ALL. Of 1,909 patients, 1,752 (92%) achieved CR and among these 757 (43·2%) relapsed; 691 (91·3%) within three years and 66 (8·7%) beyond. Among these 66 patients, median time to relapse was 47 (37–144) months. Relapse beyond three years occurred in 3·8% of all who achieved CR. The cumulative risk of relapse was 40%, 43% and 45% at three, five and ten years respectively. Out of the 1 752 patients who achieved CR, 11·7% underwent autologous and 40·6% allogeneic transplant, while in CR1. Of the autologous patients, 43·2% relapsed early and 3·4% relapsed late. However, among the allogeneic patients, 13·2% relapsed early and only 1·3% late. The five‐year overall survival from relapse was 5·8% and 20% in the early and late relapse patients respectively. In conclusion, late relapse in adults with ALL is not uncommon, and is associated with better outcome after relapse compared to early relapse.

Abstract This study was coordinated by the ECOG-ACRIN Cancer Research Group (Robert L. Comis, MD and Mitchell D. Schnall, MD, PhD, Group Co-Chairs) and the Medical Research Counsel, United Kingdom, and supported in part by Public Health Service Grants CA180820, CA180794, CA180790, CA189859, CA180853, CA180791, and from the National Cancer Institute, National Institutes of Health and the Department of Health and Human Services. Its content is solely the responsibility of the authors and does not necessarily represent the official views of the National Cancer Institute. Background: Late relapse in acute leukemia is considered a relatively rare event. Patients with acute myeloid leukemia (AML) are often considered cured of the disease at 3 years, but information regarding adult acute lymphoblastic leukemia (ALL) patients is scarce. Data are presented from one of the largest prospective adult ALL studies, the MRC UKALLXII/ECOG E2993, to evaluate the rate and characteristics of late relapse in ALL. For this purpose, late relapse was defined, arbitrarily, as relapse 3 years post achievement of complete remission (CR) and very late relapse was defined as relapse > 5 years from CR. Methods: The UKALLXII/ECOG E2993 was an international ALL trial conducted jointly by the MRC in the United Kingdom and ECOG in the United States. All patients received identical induction therapy, followed by central nervous system prophylaxis. Patients with a sibling donor (or a matched unrelated donor in Philadelophia-chromosome-positive ALL) were assigned to receive an allogeneic hematopoietic stem cell transplant (HSCT); all others were randomized to undergo an autologous transplant or protracted standard consolidation/ maintenance therapy. The study accrued 2109 patients from 1993 to 2008. Following relapse, patients were followed for survival. For this report only patients registered before the tyrosine kinase inhibitors era are included in the analysis. Results: 1518 study patients were eligible for this analysis, 1208 (79.6%) Philadelphia-chromosome negative (Ph-neg) and 267 (17.5%) Philadelphia-chromosome positive (Ph-pos). 1381 (91%) of the patients achieved CR; 93% of the Ph-neg and 82% of the Ph-pos. 572 patients (37.7%) underwent allogeneic HSCT. The median duration of follow-up of patients who achieved CR was 10 years. Among the 1381 patients who achieved CR, 626 (45.3%) had a documented relapse; 566 (90.4%) relapsed within 3 years of CR and 60 (9.6%) relapsed beyond 3 years ('late relapse') (Figure 1). Among these 60 patients, 18(2.9%) relapsed after 5 years ('very late relapse'). Table. Patients n CR All relapses Relapses< 3 years Relapses≥ 3 years Relapses≥ 5 years All patients 1518 1381 (91%) 626 (45.3%) 566 (90.4%) 60 (9.6%) 18 (2.9%) Ph-neg 1208 (79.6%) 1123 (93%) 485 (40.1%) 429 (88.5%) 56 (11.5%) 17 (3.5%) Ph-pos 268 (17.5%) 219 (82%) 124 (56.6%) 122 (98.4%) 2 (1.6%) 1 (0.8%) Relapse beyond 3 years occurred in 4.3% of all who achieved CR, in 5% of Ph-neg and 0.01% of Ph-pos patients. Among the 60 late relapses, the median time to relapse was 46 months. 61.7% of the late-relapse patients were males, median age was 32 years, 88.3% were B-lineage ALL and the median white cell count at diagnosis was 6000/ul. 56.7% were in cytogenetic standard risk, 8.3% at high risk and the data of 35% are unknown. The median survival for the late relapse patients was longer than for those who relapsed within 3 years. The overall survival (OS) of the 56 Ph-neg patients who relapsed beyond 3 years is shown in Fig 2. Table.Relapse > 3 yearsRelapse > 3 yearsMedian survival from relapse (months)5.411.23-year OS from relapse6.5%29%5-year OS from relapse5.6%19% Conclusions: Late relapses in adults with Ph-neg ALL are not uncommon. About 10% of relapses occur beyond 3 years and 4.3% of all ALL patients who achieved a CR can expect to have a late relapse. These data are in contrast to AML where only 1% of patients relapse beyond 3 years (Watts JM et al, 2014). Most of the late relapse patients were at standard risk and appeared to have a relatively favorable outcome post relapse. Patients with ALL, particularly those who are Ph-neg, cannot be considered as cured at 3 years and need to be closely followed. Figure 1. Time to relapse of Ph-pos and Ph-neg ALL Figure 1. Time to relapse of Ph-pos and Ph-neg ALL Figure 2. Survival from relapse for Ph-neg patients who relapsed after 3 years from CR. Figure 2. Survival from relapse for Ph-neg patients who relapsed after 3 years from CR. Disclosures Rowe: Amgen: Consultancy; BioSight Ltd.: Consultancy, Membership on an entity's Board of Directors or advisory committees; BioLineRx Ltd.: Consultancy. Douer:Gilead: Consultancy.

Abstract This study was coordinated by the ECOG-ACRIN Cancer Research Group (Robert L. Comis, MD and Mitchell D. Schnall, MD, PhD, Group Co-Chairs) and supported in part by Public Health Service Grants CA180794, CA180820, CA180795, CA180791, CA189859, CA180790, CA180853, and from the National Cancer Institute, National Institutes of Health and the Department of Health and Human Services. Its content is solely the responsibility of the authors and does not necessarily represent the official views of the National Cancer Institute. Background: Relapse after achieving a complete remission (CR) in AML portends for a poor prognosis and allogeneic transplant after achieving a second remission is the only chance for cure. Patients who undergo a transplant have a 30-40% chance of long term survival. This is a follow-up of a report published 10 years ago (Rowe JM, ASH 2005, abstract 546) and includes contemporary studies and longer follow-up. The study examines the long term overall survival (OS) of AML patients who relapsed after achieving first CR in 9 successive ECOG-ACRIN trials for newly-diagnosed AML patients (E3483, E3489, PC486, E3993, E4995, E1490, E3997, E1900 and E3999) from March 1984 to November 2008. Methods: OS was defined as time from first relapse to death from any cause. Kaplan-Meier estimates were used to estimate the event-time distributions for OS. Multivariate model stratified on protocol and treatment were used to examine whether the following factors are prognostic for OS from relapse: age, gender, cytogenetic risk, ECOG performance status, WBC, platelets, hemoglobin, marrow blasts, peripheral blasts, and duration of CR. All P values were based on 2-sided tests. Results: A total of 3160 patients were enrolled in the 9 studies. The median follow-up on patients still alive was 10.0 years. Among those 3160 patients enrolled, 1864 (58.9%) achieved first CR of which 1086 (58.2%) had documented relapse. The median age at diagnosis of the relapsed patients was 50 (range: 16-84) and 50.6% were males. Fifty percent of the patients had reliable cytogenetic results. Of those, 13.5% had favorable cytogenetics, 55.8% - intermediate and 30.6% had unfavorable baseline results. The median OS from relapse was 0.5 years. The 2- and 5-year OS were 16(±1)% and 10(±1)%, respectively. This is true in even the most contemporary studies (E1900 and E3999) with median OS of 0.6 and 0.4 years, respectively. By age stratification (< or ≥ 55), 5-year OS was 13(±1)% and 5(±1)%, respectively (figure 1). Among patients<55, those with unfavorable cytogenetics had the poorest prognosis (median OS of 0.4 years and 5-year OS of 6(±3)%. Those with favorable and intermediate cytogenetics had similar OS with 0.7 and 0.6 years median OS and 5-year OS of 16(±5)% and 17(±3)%, respectively (figure 2). Multivariate analysis was perfomed on 517 patients who had enough baseline information, including cytogenetics. Factors that were significantly associated with OS from relapse included: age (p<0.001), ECOG performance status (p=0.04), hemoglobin (p=0.03), cytogenetics (p=0.045) at baseline and duration of CR (p<0.001). Conclusions: The short- and long-term OS of AML patients post-relapse is dismal (<10%). Although age<55 and favorable cytogenetics at diagnosis are relatively good prognostic factors, the general survival of even these patients is very poor. Disappointingly, these data are also applicable to the most contemporary studies. Long-term survival was possible only in the minority of patients who survived the relapse, achieved a second CR and then successfully underwent an allogeneic transplant. These data are crucial when considering post-remission strategy, and suggest that offering a therapy most likely to lead to cure in CR1 is the preferred option. Figure 1. Probability of OS from relapse by age group Figure 1. Probability of OS from relapse by age group Figure 2. Probability of OS from relapse by cytogenetic risk for patients age <55 Figure 2. Probability of OS from relapse by cytogenetic risk for patients age <55 Disclosures Douer: Gilead: Consultancy. Rowe:BioSight Ltd.: Consultancy, Membership on an entity's Board of Directors or advisory committees; BioLineRx Ltd.: Consultancy; Amgen: Consultancy.

Abstract The identification of mutations in BRAFV600E and other kinases in systemic histiocytoses changed our understanding of the pathophysiology of these disorders from inflammatory non-malignant conditions to clonal disorders driven by altered MAP kinase signaling. In addition, BRAFV600E mutations have recently been noted in bone marrow (BM) CD34+ cells of patients with Langerhans Cell Histiocytosis (LCH), suggesting that LCH represents a clonal disorder arising from hematopoietic stem/progenitor cells (HSPCs). However, it is unknown if HSPCs from LCH or other histiocytoses patients can functionally give rise to these disorders. Moreover, whether or not patients with histiocytosis have additional hematological disorders related to the presence of HSPC-based mutations is unclear. Here we attempted to understand the spectrum of hematological disorders in patients with histiocytoses and the cell-of-origin of histiocytic neoplasms by functionally analyzing HSPCs from histiocytoses patients. We first analyzed a multicenter cohort of 190 adult histiocytoses patients. This unexpectedly identified a high frequency of patients with a co-existing myeloid malignancy. Of the 190 patients, 9.5% (18/190) were diagnosed with Erdheim-Chester Disease (ECD) and/or LCH concomitantly with a classic MPN (3.7%; 7/190), MPN/MDS overlap (4.7%; 9/190), or MDS (1.1%; 2/190) (Figure). This clinical observation was confirmed by detection of co-existing histiocytoses-associated kinase mutations (including BRAF, MAP2K1, NRAS, or KRAS mutations) with JAK2 or CALR mutations, as well as other mutations recurrently found in myeloid malignancies (such as IDH1/2, ASXL1, and TET2 mutations (Figure)). These data therefore reveal a heretofore-unrecognized clinical overlap of adult-onset systemic histiocytoses and WHO-classified myeloid malignancies while further highlighting the possibility of an aberrant HSPC origin for histiocytic neoplasms. In most cases, the BRAF/MAP2K1/RAS mutation predominated in the histiocytic lesion while the JAK2/CALR mutation predominated in the BM/peripheral blood suggesting likely distinct clones driving each clinical condition. Next, to test the self-renewal and differentiation capacity of HSPCs from histiocytoses patients, CD34+ cells were purified from 8 patients including 6 with ECD or LCH plus a concomitant myeloid neoplasm, and 2 with ECD alone. 0.1-0.8x106 CD34+ cells from each patient were transplanted by intrafemoral injection into sublethally irradiated NOD/SCID IL2Rγ transgenic human GM-CSF, IL-3, and SCF expressing (NSG-SGM3) mice. Human engraftment was monitored by monthly flow cytometric analysis of peripheral blood until mice became moribund. Thereafter, animals were sacrificed and tissues were analyzed using flow cytometry, histology, immunohistochemistry, and sequencing analyses to detect driver mutations identified in the histiocytosis/co-occurring myeloid neoplasm. Successful engraftment of human myeloid cells was verified in grafts generated from 2/8 patients after a mean of 90 days (range: 60-120 days). This included lethal engraftment of KRAS-mutated ECD patient cells at 90 days manifested by infiltration of human hCD45+ cells co-expressing human myeloid and monocyte lineage markers hCD33 and hCD14 in the bone marrow, spleen, liver, lung, and kidney (Figure). Immunostains revealed that tissues were infiltrated by an hCD45+hCD163+hCD68+ population of foamy histiocytes, characteristic of ECD (Figure). Furthermore, genomic analysis of DNA from the engrafted animals BM and spleen revealed the same KRASG12S mutation found in the donor patients ECD lesion. Engraftment of a patient diagnosed with concomitant BRAFV600E-mutant ECD and ASXL1/TET2-mutant CMML was seen at 60 days. In this case, however, only engraftment of human CMML was detected without evidence of the BRAFV600E-mutant ECD component. This study suggests that adult histiocytic neoplasms frequently co-occur with other myeloid neoplasms. Moreover, histiocytosis disease-driver mutations are present in the CD34+ HSPCs, which we show for the first time can initiate disease that resembles human histiocytosis in a patient-derived xenograft. Importantly, however, even though the CD34+ compartment gives rise to both the histiocytic and myeloid neoplasm disease component, each disease is likely initiated by distinct precursors. Figure. Figure. Disclosures No relevant conflicts of interest to declare.

Abstract Background Extramedullary disease (EMD) of acute myeloid leukemia (AML) was described decades ago but the incidence of this phenomenon and its prognostic impact are not clear. It is also uncertain whether every site of EMD has the same significance. This study explored these questions using a large cohort of AML patients treated on consecutive Eastern Cooperative Oncology Group (ECOG) frontline clinical trials. Methods For AML patients enrolled into ECOG clinical trials, the presence of EMD was captured at baseline on case report forms. From patients with newly diagnosed AML, age 15 and above, who were treated on 11 consecutive different clinical trials, we identified those with or without EMD, defined by physical examination, laboratory findings and imaging, without necessarily a biopsy. We used descriptive statistics to summarize patient and disease characteristics. Univariate analyses of potential prognostic factors were done. The Kaplan-Meier method was used to estimate median overall survival (OS) within each prognostic category and differences were explored using the log-rank test. Cox proportional hazards models were used to examine the effect of one-unit increases in continuous variables on OS and for multivariable analyses. Multivariate models were built using backward selection. Factors (or groups of factors) significant at the 0.10 level in univariate analyses were tested for inclusion in the model, and retained if they were significant at the 0.05 level. Results Of the 3,522 patients enrolled in 11 different AML clinical trials, we excluded 281; for diagnosis of other types of leukemia (n=220), no EMD evaluation at baseline (n=41) or no survival data (n=20). The overall incidence of EMD was 23.8% (770 out of the remaining 3,241 patients). The sites involved were: lymph nodes 367 (11.3%) patients, spleen 234 (7.2%), liver 173 (5.3%), skin 146 (4.5%), gingiva 104 (3.2%), central nerve system (CNS) 32 (1%), peripheral nerve system (PNS) 8 (0.2%) and other sites 134 (4.1%). In 65 cases (8.4%) EMD was confirmed by biopsy. Most of the patients (64.4%) had only one site of EMD, 163 (21.2%) had 2 sites, 75 (9.7%) - 3 sites, 28 (3.6%) - 4 sites, and 4 patients (0.5%) each had 5 or 6 sites. EMD patients compared to those without EMD; tend to be younger (median age 45.7 vs 52.9 years); male (57.7% vs 52%); poorer ECOG performance status (76.4% with ECOG 0-1 vs 85.9%) and with higher white blood cell count (WBC) at diagnosis (median of 41.6/µl vs 10.2/µl). In univariate analysis, having EMD was associated with a shorter OS (P=0.006). Examination of individual EMD sites revealed that skin (P=0.002), spleen (P=0.0002) and liver (P=0.0007) but not CNS (P=0.35), PNS (P=0.53), nodal involvement (P=0.85) and gingival hypertrophy (P=0.14), were associated with poorer OS. Using proportional hazards models for continuous factors, each additional site of EMD conferred a 9.4% increase in the risk of death. In a multivariable model, after adjusting for known prognostic factors (such as: age, WBC count and cytogenetic risk group), the presence of EMD, number of EMD sites and any specific EMD site were not independently prognostic. Of 165 patients with known favorable cytogenetics EMD was present in only 22 patients (13%). This group appeared to have a worse prognosis, but the numbers are too small for a definitive assessment (figure 1). Conclusions Extramedullary disease is common in newly diagnosed AML with an incidence of almost 24%, but CNS involvement is very rare (0.95%). In contrast to published data, no site of EMD was found to have an independent prognostic impact in multivariate analysis. This large dataset emphasizes the importance of evaluating large number of patients and considering all known risk factors in the multivariate analysis. Disclosures: No relevant conflicts of interest to declare.

AbstractThis study examines the long‐term OS of relapsed AML patients who were enrolled to 9 successive ECOG‐ACRIN trials for newly diagnosed AML, during 1984‐2008. The objectives were to examine whether there is a trend of improvement in the survival of relapsed AML patients in the more recent studies and to search for prognostic factors that are associated with long‐term OS after relapse. A total of 3012 patients were enrolled, 1779 (59.1%) achieved CR1 and of these, 58.9% relapsed. The median follow‐up was 9.7 years. The median OS from relapse was 0.5 years and the 5‐year OS was 10 (±1)%. These results were similar even for the most recent studies. A multivariate model showed that age, cytogenetics at diagnosis, duration of CR1 and undergoing allogeneic transplantation were significantly associated with OS from relapse. Even among patients who relapsed with better prognostic factors; age < 40 and CR1 > 12 months, there was no significant OS difference between the studies. In conclusion, this large cohort appears to confirm that the survival of AML patients postrelapse continues to be dismal and has not improved during the past quarter of a century.

Purpose Extramedullary disease (EMD) at diagnosis in patients with acute myeloid leukemia (AML) has been recognized for decades. Reported herein are results from a large study of patients with AML who were treated in consecutive ECOG-ACRIN Cancer Research Group frontline clinical trials in an attempt to define the incidence and clinical implications of EMD. Methods Patients with newly diagnosed AML, age 15 years and older, who were treated in 11 clinical trials, were studied to identify EMD, as defined by physical examination, laboratory findings, and imaging results. Results Of the 3,522 patients enrolled, 282 were excluded, including patients with acute promyelocytic leukemia, incorrect diagnosis, or no adequate assessment of EMD at baseline. The overall incidence of EMD was 23.7%. The sites involved were: lymph nodes (11.5%), spleen (7.3%), liver (5.3%), skin (4.5%), gingiva (4.4%), and CNS (1.1%). Most patients (65.3%) had only one site of EMD, 20.9% had two sites, 9.5% had three sites, and 3.4% had four sites. The median overall survival was 1.035 years. In univariable analysis, the presence of any EMD ( P = .005), skin involvement ( P = .002), spleen ( P < .001), and liver ( P < .001), but not CNS ( P = .34), nodal involvement ( P = .94), and gingival hypertrophy ( P = .24), was associated with a shorter overall survival. In contrast, in multivariable analysis, adjusted for known prognostic factors such as cytogenetic risk and WBC count, neither the presence of EMD nor the number of specific sites of EMD were independently prognostic. Conclusion This large study demonstrates that EMD at any site is common but is not an independent prognostic factor. Treatment decisions for patients with EMD should be made on the basis of recognized AML prognostic factors, irrespective of the presence of EMD.