Citations

Abstract Background: MDSs are clonal hematopoietic stem cell malignancies characterized by cytopenias resulting from ineffective hematopoiesis. A phase 2 study of lenalidomide (MDS-002) demonstrated hematological improvement in patients with MDS without an associated deletion 5q cytogenetic abnormality (List AF, et al. Haematologica2006;91[suppl1]:379[abst 1032]). We now report multicenter results after 〉2 yrs follow-up. Methods: A total of 214 pts with transfusion-dependent anemia were categorized into the following IPSS MDS risk groups after central review of bone marrow morphology, karyotype, and peripheral blood findings: Low/Int-1 (168 [78%]); Int-2/High (8 [4%]); and unclassified (38 [18%]). Patients were unclassified for missing or inadequate marrow studies for central review (morphology [29] or cytogenetic [7]) or other diagnoses (AML [1], atypical CML [1]). Patients were evaluated for frequency and duration of red blood cell transfusion independence (RBC-TI) (IWG criteria), hemoglobin (Hgb) response, and safety. The starting dose of lenalidomide was 10 mg (daily or daily × 3 wks q28d cycle). Results: Overall, 56 (26%) of 214 enrolled patients achieved RBC-TI. Median time to RBC-TI was 5 wks, median duration of RBC-TI response was 41.0 wks (range, 8.0–136.4), and median Hgb increase achieved during RBC-TI was 3.2 g/dL (range, 1.0–9.8). An additional 36 patients experienced a ≥ 50% reduction in RBC transfusions (overall hematological improvement in 92 [43%] patients). Overall, 47 (22%) patients had an abnormal karyotype at baseline and 9 (19%) patients achieved a cytogenetic response (4 complete). The most common drug-related grade 3/4 adverse events (AEs) were neutropenia and thrombocytopenia (25% and 20%, respectively). Deep vein thrombosis occurred in only 2 (1%) patients. The duration of RBC-TI was ≥ 52 weeks in 21 (38%) patients. Among these 21 patients, 14 (67%) did not require a lenalidomide dose reduction during the first 52 weeks of treatment. Analyses of response variables will be presented. Dose-limiting neutropenia/thrombocytopenia was not reported after 52 weeks. The most commonly reported AEs after 52 weeks were mild-moderate diarrhea and fatigue (38% and 29%, respectively). Conclusion: Lenalidomide is an active, well-tolerated treatment in MDS patients with transfusion-dependent anemia that is not associated with a deletion 5q abnormality. The rate of erythroid hematologic improvement and duration of RBC-TI is encouraging and offers a possible alternative to cytokine therapy.

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 Background: Myelodysplastic syndromes (MDS) are hematological disorders characterized by chronic anemia, and are often refractory to cytokine therapy. Two phase 2 studies evaluating lenalidomide in MDS (MDS-001 and MDS-003), demonstrated a high frequency of erythroid response in patients with a chromosome 5q31 deletion (List AF et al., N Eng J Med2005; 352:549–557 and List AF et al., in press). Herein we report on the durability of response with long term follow-up approaching 4 years. Methods: All enrolled subjects were evaluated for frequency and duration of red blood cell transfusion independence (RBC-TI), change in hemoglobin (Hgb), pathologic and cytogenetic response, and safety. Results: Ten 5q31- patients achieved a cytogenetic and/or major erythroid response in MDS-001. Four of these patients have maintained a major response for at least 2 years (range 2.2 to 3.7 years). In MDS-003, 99 (67%) of 148 enrolled patients achieved RBC-TI. Of the 99 responders 83 were Low/Int-1, 3 were Int-2/High and 13 were not classified. Median increase in Hgb from baseline to maximum achieved during RBC-TI was 5.4 g/dL (range 1.1, 11.4). The estimated median duration of response was 115.9 weeks, and 52 (53%) of 99 responders remain on study with ongoing RBC-TI response as of 30 June 2006. Duration of response was at least 52 weeks for 63 (64%), 78 weeks for 52 (53%), and 104 weeks for 36 (36%) of 99 responding patients. Variables (or co-variates) associated with longer duration of TI in multivariate analysis included low baseline transfusion requirement (<4 units per 8 wks, p=0.002), 5q- syndrome (p=0.01) and low IPSS (p=0.02) classifications. Among 85 evaluable patients, major cytogenetic responses were achieved in 37 (44%) and minor responses in 24 (28%). Cytogenetic responses occurred in patients with complex karyotypes as well as those with an isolated 5q31 deletion. The frequencies of major and minor cytogenetic responses were similar among patients with and without 5q- syndrome. The most common drug-related adverse events (AE) were Grade 3/4 neutropenia and thrombocytopenia, reported in 87 (59%) and 74 (50%) of 148 patients, respectively although hematologic AEs led to study discontinuation in only 13 (9%) of patients. Pneumonia was the only serious adverse event that occurred in >10% of patients (15/148; 10%). Adverse events were manageable through supportive treatment and dose reduction. Conclusion: Lenalidomide is an effective treatment in MDS patients with an associated chromosome 5q31 deletion, with RBC-TI and major erythroid response maintained for median duration > 2 years.

Abstract Background: Patients diagnosed with cancer experience a significant influx of health care information while continuing to demonstrate understanding deficit regarding their disease and health. This knowledge deficit can negatively impact a patient’s acute and long term health care experience. By identifying patient information deficits and needs, health care providers may be better able to provide targeted education to patients and families. Aims: The aim of this study is to evaluate the impact of a patient centered cancer symposium on knowledge level, reported symptom burden, and desired information from a broad population of cancer patients. Methods: Surveys were distributed to the attendees of the third annual Mayo Clinic “Living with Cancer” patient symposium in January 2014. While 700 individuals registered for the event, only individuals with a past or present cancer diagnosis were asked to participate. Surveys included demographic data in addition to a questionnaire evaluating disease comprehension, symptom burden, desired information and desired role in the health care decision making process. Results: 75 patients completed the pre-intervention and post-intervention survey. There were slightly more female participants (60.2%). Disease types included 40% hematologic malignancies, 27% breast cancer, 20% prostate cancer and 13% other. The majority of patients were greater than 3 years from cancer diagnosis (62%). Baseline Patient Understanding: Most respondents reported understanding their disease quite a bit (54%) or very much (30%). Respondents reported the majority of their knowledge regarding their disease came from their oncologist (56%), oncology nurse (24%), previous symposiums (22%), or the internet (15%). Most respondents reported “quite a bit” or greater comprehension of screening tests (75%), monitoring disease response to treatment (70%), monitoring disease recurrence (70%), treatment options (67%) and treatment side effects (73%). There was no consensus among participants regarding understanding or limiting risk factors, symptoms associated with disease relapse, fatigue and pain management, navigating the health care system, financial considerations, or confidence in their primary care physician’s involvement in their cancer or post-cancer care. A large proportion of attendees reported “quite a bit” or greater desire for increased information/understanding regarding their disease (83%), risk factors (83%), nutrition (80%), screening tests (69%), and management of fatigue (69%) and stress (68%). Knowledge Improvement Durable at 3 months: There was improvement in 18 of 20 areas of self-reported knowledge. This was noted in increased percentage of respondents reporting “quite a bit” or greater comprehension, especially in areas of disease risk factors(55%pre vs 63%post), disease side effects(55%pre vs 63%post), and health care navigation(53%pre vs 69%post). The reported desire for “quite a bit” or more increased understanding on various topics did decrease post symposium regarding their disease(87.9% pre vs 68.9%post), disease risk factors(86.3%pre vs 64.0%post), screening tests(74.7%pre vs 63.3%post), and nutrition(78.4%pre vs 64.9%post)(all p<0.05). There was no significant decrease in the desire for increased understanding managing stress and fatigue. Summary: Demonstrated in this study, individuals choosing to attend a patient-centered cancer symposium, seek to improve an already solid knowledge base. Study participants indicate a significant desire for increased information on all topics, even those with sufficient level of knowledge reported. This indicates that some cancer patients’ thirst for knowledge is difficult to quench, and may benefit from recurrent education opportunities. The improvement in almost all topics assessed indicates a patient centered symposium is an effective method to provide information to patients regarding the spectrum of cancer health management. Disclosures No relevant conflicts of interest to declare.

Abstract Background: A cancer diagnosis results in a multitude of health care decisions that require adequate patient understanding to navigate the health care system. Understanding the type and degree of information needs of cancer patients is imperative to instructing effective and pertinent patient education. This study sought to evaluate the impact of a patient centered cancer symposium on knowledge level, knowledge needs and symptom burden in a cancer patient population. Methods: Surveys were distributed to attendees of the Mayo Clinic "Living with and Surviving Cancer" patient symposium in January 2016. A follow up survey was sent to participants 3 months after the symposium. Surveys included demographic data, questionnaire evaluating disease comprehension and information assessment, symptom burden, desired information and quality of life assessment. Responses were compared between patients with hematologic and solid tumor malignancies by chi-square test. Pre and post comparisons were done in patients completing both surveys by McNemar test. Results: Demographics: 150 patients completed the pre-intervention survey. Average age of participants 67.5 years. Some patients reported more than 1 malignancy. Disease types represented included hematologic malignancies (N=60), specifically multiple myeloma (N=23), lymphoma (N=26), leukemia (N=8) and MPNs (N=3) as well as solid tumor malignancies (N=90). Most patients were diagnosed with cancer at least 1 year prior to the intervention (N=137). Patients with hematologic malignancies were more likely to be on active treatment at the time of the convention (N=35, 58%) compared to solid tumor malignancies (N=37,41%). Baseline Knowledge: Most patients reported an adequate level of knowledge defined as the proportion of participants reporting "quite a bit" or "very much understanding" on the topic of disease understanding (76%). Lowest levels of knowledge were legal issues (18%), pain management (31%), disease relapse symptoms(46%), fatigue management (48%), end of life decision making (50%) and financial management (50%). Patients with hematologic malignancies were more likely to report understanding of fatigue management (N=36, 60%) but less like to report understanding disease risk factors (N=20, 33%), or increased nutritional interest following diagnosis (N=32, 53%) compared to solid tumor malignancy (N=33,37%) (N=55,61%)(N=70,78%), respectively (all p <0.05). The EORTC-INFO25 at baseline revealed hematologic patients had received less information on sexual side effects of treatments (N=7, 14%) compared to solid tumor patients (N=30, 35%; p=0.004), and reported a lower score of treatment information (50 vs 59; p=0.04). Pre and Post Analysis: Of the 150 initial participants, 81 completed the pre and post-convention surveys (54%). Post-symposium, significant improvement defined as the proportion of participants reporting "quite a bit" or "very much" understanding was noted of disease (pre 75% vs post 89%), stress management (pre 56% vs post 69%), maintain relationships (pre 60% vs post 75%) and pain management (pre 33% vs post 51%)(p-value<0.05). The desire for increased information decreased post-symposium regarding all 9 topics, with significant decreases noted in disease, treatment options and side effects, legal issues and stress management. The EORTC INFO25 analysis revealed a decrease in the reported desire for more information (mean; pre 70 vs post 53, p-value <0.05) Discussion: Cancer patients have a variety of information needs. A patient centered educational conference was able to produce significant improvement in understanding in 4 of 17 topics (24%), including general disease, stress and pain management, and relationship maintenance that was durable at 3 months. At least some improvement in understanding was noted in 10 of 17(59%) additional topics. Knowledge deficit improved in all 9 topics assessed, significantly in five. Cancer patient knowledge needs are varied, and likely evolve over time as a patient progress through stages of disease and treatment. Education should re-evaluate and redistribute information to cancer patients over the course of treatment and survivorship. Disclosures Mikhael: Abbvie: Research Funding; Celgene: Research Funding; Sanofi: Research Funding; Onyx: Research Funding. Dueck:Bayer: Honoraria. Mesa:Novartis: Consultancy; Ariad: Consultancy; Promedior: Research Funding; Galena: Consultancy; Incyte: Research Funding; Celgene: Research Funding; CTI Biopharma: Research Funding; Gilead: Research Funding.

Abstract Background: A diagnosis of cancer leads to significant information requirements to facilitate health care decision making, understand management options, and health care system navigation. Many patients demonstrate a knowledge deficit that can lead to decreased quality of life and poor health care compliance. This study sought to evaluate the impact of a patient centered cancer symposium on knowledge level, symptom burden, and desired information in a broad population of cancer patients. Methods: Surveys were distributed to attendees of the Mayo Clinic "Living with and Surviving Cancer" patient symposium in January 2015. A follow up survey was sent to participants 3 months after the symposium. Surveys included demographic data, questionnaire evaluating disease comprehension, symptom burden, desired information and quality of life. Results: Demographics: 113 patients completed the pre-intervention survey. Average age of participants was 64.7 years. Disease types represented included hematologic malignancies (N=50), specifically multiple myeloma (N=24), lymphoma (N=17), leukemia (N=6), MPN/MDS (n=3), as well as solid tumor malignancies (N=77). Highest knowledge topics were disease (80%), screening tests (74%), and monitoring tools (72%). Lowest knowledge topics were financial management (13%), legal issues (13%), and pain management (35%). Pre and Post Analysis: Of the 113 initial participants, 79 patients completed the pre- and post-symposium surveys. In the post-symposium setting significant improvement was noted in understanding of disease (pre 80% vs post 92%), treatment options (pre 60% vs post 76%), nutrition (pre 68% vs post 84%) and legal issues (pre 15% vs post 32%). Non-significant knowledge improvement was noted in areas of risk factors and symptoms, screening/monitoring tools, disease side effects, managing stress/fatigue, end of life decision making and health care navigation. Most patients desired increased understanding regarding disease, screening tests, nutrition, and stress and fatigue management. The level of patient reported desire for information of these topics decreased in the post-symposium setting, statistically significant decrease noted in 4 of 5 topics assessed. In hematology patients who completed pre and post surveys (N=36), a higher level of baseline knowledge was reported regarding disease understanding (89%), tools monitoring response (83%) and recurrence (75%), symptoms (83%), relapse symptoms (64%) and treatment options (72%). In this group the decrease in desire for information was less prominent in the post-symposium setting. Discussion: This data demonstrates improved patient reported understanding on a variety of topics with durable response at 3 months. A majority of patients reported adequate baseline knowledge of many topics prior to the symposium but also a desire of increased cancer specific information. Knowledge deficit in cancer care includes disease specific topics, social stressors and health care navigation. The percentage of participants reporting a high desire for more information remained high but did decrease, suggesting decreased knowledge deficit in the post-symposium setting. Patient education should strive to be accessible, all-inclusive and reactive to patient needs. Table 1.Reported "quite a bit" or "very much" understanding and desired information regarding cancer carePrePostP-valueN=79(%)N=79(%)I understand…How to manage financial considerations of my disease/treatment39(51)41(53)0.85How to manage my pain24(34)23(32)0.81Risk factors that can lead to my disease37 (49)42 (56)0.56How to navigate the health care system43(55)47(60)0.56How to manage fatigue38(50)43(56)0.54Process of making end of life decisions33(47)41(53)0.52Screening tests60 (76)63 (81)0.5Symptoms associated with relapse35(45)42(54)0.27Disease symptoms54(70)60(76)0.2Tools monitoring recurrence49(62)56 (72)0.19Tools monitoring response56(71)63(81)0.15How to manage stress46(60)56(71)0.12Legal issues of my disease11(15)24(32)<0.05Treatment options47(60)60(76)<0.05What to eat49(68)66(84)<0.05My disease62(80)71(92)<0.05I desire increased understanding…Of my disease59(77)53(70)0.4Of managing stress50(65)35(51)<0.05Regarding nutrition64(84)54(70)<0.05Of the screening tests62(79)43(57)<0.05How to manage fatigue54(72)42(54)<0.05 Disclosures Tibes: TetraLogic Pharmaceuticals: Research Funding. Mesa:Novartis. Research- incyte, Gilead, cti, Genentech, promedior, NS Pharma: Consultancy.

Abstract Abstract 1845 Poster Board I-871 Background: Proteasome inhibition is an effective strategy for the treatment of multiple myeloma. In patients, proteasome inhibition has primarily been measured in peripheral blood samples (whole blood or mononuclear cells). However, it is unknown whether myeloma cells in the bone marrow (BM) are equally sensitive to proteasome inhibitors such as bortezomib (BTZ) and carfilzomib (CFZ). Aim: To measure proteasome inhibition in purified tumor cells from BM samples taken from patients enrolled in two ongoing Phase 2 trials of single agent CFZ in relapsed or refractory myeloma: PX-171-003 (003) and PX-171-004 (004). Methods: CFZ was administered as an IV bolus of 20 mg/m2 on Days 1, 2, 8, 9, 15 and 16 of a 28-day cycle on both trials. Bone marrow samples, from an optional sub-study of both trials, were taken during screening and Day 2 (post-treatment) and sorted into CD138+ and CD138− cells. Proteasome activity was measured by an enzymatic assay using a fluorogenic substrate (LLVY-AMC) for the chymotrypsin-like (CT-L) activity and an active site ELISA (ProCISE) to quantitate levels of the CT-L subunits of the constitutive proteasome (Beta5) and immunoproteasome (LMP7) and the immunoproteasome subunit MECL1. Results: Whole blood samples from patients treated with CFZ showed inhibition of CT-L activity of ∼80+, similar to values obtained in Phase 1 studies. A total of 10 CD138+ screening samples, 6 from 004 and 4 from 003, and 9 post-dose samples, 5 from 004 and 4 from 003, were analyzed for proteasome levels and activity. In addition, 15 CD138−screening samples, 7 from 004 and 8 from 003, and 9 post-dose samples, 5 from 004 and 4 from 003, were analyzed. When compared to the average base-line activity, CFZ treatment resulted in 88% CT-L inhibition in CD-138+tumor cells from 004 patients (P = 0.0212 by unpaired t-test) and 59% CT-L inhibition in CD-138+ tumor cells from 003 patients (P = 0.25). Baseline CT-L activity in CD138+ tumor cells was 3-fold higher in 004 than 003, which includes a more heavily pre-treated patient population with greater prior exposure to BTZ. Higher specific enzymatic activity was due to increased levels of both constitutive and immunoproteasomes in tumor cells, where immunoproteasomes account for >75% of total cellular proteasomes. No differences between trials were seen in baseline CT-L activity from non-tumor (CD138−) cells. Inhibition in CD138− cells was 84% (P = 0.0380 and 42% (P = 0.38) in 004 and 003, respectively. Using ProCISE, we measured inhibition of LMP7 (66%), beta5 (48%) and MECL1 (64%) in CD138+ tumor cells from 004 patients. Three patients from 004 and one from 003 had both a screening and post-dose tumor cell samples available for analysis. Inhibition of CT-L activity was >80% in two of the 3 patients on 004; the third patient showed no proteasome inhibition by ProCISE and was unavailable for analysis by CT-L. CT-L activity in the CD138+ tumor cells in the 003 patient was not inhibited, however, inhibition was seen in non-tumor cells. Conclusions: CFZ inhibits the proteasome activity of myeloma cells in the bone marrow of relapsed and refractory myeloma patients. The levels of inhibition were similar to those measured in whole blood samples, supporting the use of the blood-based assay as a surrogate marker for proteasome inhibition in tumor cells. CFZ treatment resulted in inhibition of both CT-L subunits as well as additional subunits of the immunoproteasome in tumor cells. Reduced baseline activity in the more heavily pretreated 003 patients may reflect reduced tumor-dependency on the proteasome and may be related to prior treatment with BTZ in these patients. More samples are needed in order to make correlations between levels of proteasome inhibition in bone marrow tumor cells and prior therapies or response. These observations support further evaluation of proteasome activity and the effects of this promising new agent in primary tumors cells from myeloma patients. Disclosures: Trudel: Celgene: Honoraria, Speakers Bureau; Ortho Biotech: Honoraria. Lee:Proteolix, Inc.: Employment. Kirk:Proteolix, Inc.: Employment. Lonial:Celgene: Consultancy; Millennium: Consultancy, Research Funding; BMS: Consultancy; Novartis: Consultancy; Gloucester: Research Funding. Wang:Proteolix, Inc.: Research Funding. Kukreti:Celgene: Honoraria. Stewart:Genzyme, Celgene, Millenium, Proteolix: Honoraria; Takeda, Millenium: Research Funding; Takeda-Millenium, Celgene, Novartis, Amgen: Consultancy. Jagannath:Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Merck: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. McDonagh:Proteolix: Research Funding. Zonder:Celgene: Speakers Bureau; Pfizer: Consultancy; Seattle Genetics, Inc.: Research Funding; Amgen: Consultancy; Millennium: Research Funding. Bennett:Proteolix: Employment.

Abstract Abstract 2203 Background: Thrombotic thrombocytopenic purpura (TTP) is frequently characterized by severe ADAMTS13 deficiency, the cause of which is unknown. An important exception is ticlopidine-associated TTP (tc-TTP), the most common drug-induced TTP syndrome. In 1998, a possible association of TTP with ticlopidine was reported. In 1999, two additional series reported this association. In 2000, a fourth study reported severe A DAMTS13 deficiency among six of seven tc-TTP persons- suggesting a causal pathway. All of these reports were from the United States. Recently, we reported characteristics of 186 acquired idiopathic (ai)- TTP patients in Japan with severe ADAMTS13 deficiency, noting that clinical and laboratory findings for ai-TTP patients in Japan differed from those for cohorts of ai-TTP patients in Europe and North America- raising concern that TTP findings vary by region of the world. (PLOS One 2011) We now on report clinical and laboratory characteristics of a cohort of TTP patients from Japan with tc-TTP, and compare these findings to three cohorts of tc-TTP in the United States and one cohort of ai-TTP patients from Japan. Methods: We queried a database of thrombotic microangiopathy patients identified from a national TTP referral laboratory in Japan of cases identified between 1998 and 2008. Severe ADAMTS13 deficiency was characterized by activity levels < 5%. All tc-TTP patients and 186 of 911 ai-TTP patients in the database had severe ADAMTS13 deficiency and first onset of TTP. Comparisons were made to tc-TTP patients reported previously from the United States. Results: Characteristics of ai- TTP with severe ADAMTS13 deficiency in Japan and tc-TTP in Japan and US Conclusions: These data from Japan validate insights about tc-TTP initially proposed in 1998, 1999, and 2000 in the United States. Ticlopidine is a likely cause of TTP, the mechanism is via a cross-reactive antibody to ADAMTS13:AC resulting in formation of an ADAMTS13:INH, and therapeutic plasma exchange is necessary for treatment. Disclosures: Ortel: Eisai: Research Funding; Glaxo SmithKline: Research Funding; Pfizer: Research Funding; Instrumentation Laboratory, Inc: Consultancy, Research Funding; Boehringer Ingelheim: Consultancy. Fujimura:Baxter BioScience: Membership on an entity's Board of Directors or advisory committees; Alexion Pharma: Membership on an entity's Board of Directors or advisory committees.