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Supplementary Table from A Phase I Study of an MPS1 Inhibitor (BAY 1217389) in Combination with Paclitaxel Using a Novel Randomized Continual Reassessment Method for Dose Escalation

Supplementary Figure from A Phase I Study of an MPS1 Inhibitor (BAY 1217389) in Combination with Paclitaxel Using a Novel Randomized Continual Reassessment Method for Dose Escalation

Supplementary Data from A Phase I Study of an MPS1 Inhibitor (BAY 1217389) in Combination with Paclitaxel Using a Novel Randomized Continual Reassessment Method for Dose Escalation

Purpose:Monopolar spindle 1 (MPS1) kinase inhibitor, BAY 1217389 (BAY) synergizes with paclitaxel. This phase I study assessed the combination of BAY with paclitaxel using a novel randomized continuous reassessment method (rCRM) to improve dose determination.Patients and Methods:Patients with solid tumors were randomized to receive oral BAY (twice daily 2-days-on/5-days-off) with weekly paclitaxel (90 mg/m2) or paclitaxel monotherapy in cycle 1. Dose escalation was guided by CRM modeling. Primary objectives were to assess safety, establish the MTD of BAY, and to evaluate the pharmacokinetic profiles for both compounds. Simulations were performed to determine the contribution of the rCRM for dose determination.Results:In total, 75 patients were enrolled. The main dose-limiting toxicities were hematologic toxicities (55.6%). The MTD of BAY was established at 64 mg twice daily with paclitaxel. Inclusion of a control arm enabled the definitive attribution of grade ≥3 neutropenia to higher BAY exposure [AUC0–12 (P< 0.001)]. After determining the MTD, we included 19 patients with breast cancer at this dose for dose expansion. Other common toxicities were nausea (45.3%), fatigue (41.3%), and diarrhea (40.0%). Overall confirmed responses were seen in 31.6% of evaluable patients. Simulations showed that rCRM outperforms traditional designs in determining the true MTD.Conclusions:The combination of BAY with paclitaxel was associated with considerable toxicity without a therapeutic window. However, the use of the rCRM design enabled us to determine the exposure–toxicity relation for BAY. Therefore, we propose that the rCRM could improve dose determination in phase I trials that combine agents with overlapping toxicities.

Supplementary Figure 1 from Efficacious Immune Therapy in Chronic Myelogenous Leukemia (CML) Recognizes Antigens That Are Expressed on CML Progenitor Cells

Supplementary Tables 1-3, Figure Legend from Efficacious Immune Therapy in Chronic Myelogenous Leukemia (CML) Recognizes Antigens That Are Expressed on CML Progenitor Cells

Purpose: Monopolar spindle 1 (MPS1) kinase inhibitor, BAY 1217389 (BAY) synergizes with paclitaxel. This phase I study assessed the combination of BAY with paclitaxel using a novel randomized continuous reassessment method (rCRM) to improve dose determination. Patients and Methods: Patients with solid tumors were randomized to receive oral BAY (twice daily 2-days-on/5-days-off) with weekly paclitaxel (90 mg/m2) or paclitaxel monotherapy in cycle 1. Dose escalation was guided by CRM modeling. Primary objectives were to assess safety, establish the MTD of BAY, and to evaluate the pharmacokinetic profiles for both compounds. Simulations were performed to determine the contribution of the rCRM for dose determination. Results: In total, 75 patients were enrolled. The main dose-limiting toxicities were hematologic toxicities (55.6%). The MTD of BAY was established at 64 mg twice daily with paclitaxel. Inclusion of a control arm enabled the definitive attribution of grade ≥3 neutropenia to higher BAY exposure [AUC0–12 (P< 0.001)]. After determining the MTD, we included 19 patients with breast cancer at this dose for dose expansion. Other common toxicities were nausea (45.3%), fatigue (41.3%), and diarrhea (40.0%). Overall confirmed responses were seen in 31.6% of evaluable patients. Simulations showed that rCRM outperforms traditional designs in determining the true MTD. Conclusions: The combination of BAY with paclitaxel was associated with considerable toxicity without a therapeutic window. However, the use of the rCRM design enabled us to determine the exposure–toxicity relation for BAY. Therefore, we propose that the rCRM could improve dose determination in phase I trials that combine agents with overlapping toxicities.

The authors did not submit an updated abstract. The original abstract should be considered final. Citation Format: Sarina Piha-Paul, Johanna C. Bendell, Anthony Tolcher, Rachna Shroff, Paula R. Pohlmann, Sara A. Hurvitz, Anuradha Krishnamurthy, Naimish Pandya, Shane A. Olwill, Markus Zettl, Kayti Aviano, Lynn Mar, Patrick Jolicoeur, Aizea Morales Kastresana, Corinna Schlosser, Ingmar Bruns, Alice Bexon, Geoffrey Y. Ku. Clinical and biomarker activity of PRS-343, a bispecific fusion protein targeting 4-1BB and HER2, from a phase 1 study in patients with advanced solid tumors (Study PRS-343-PCS_04_16) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT017.

Background Anticalin® proteins are recombinantly engineered human proteins based on lipocalins. PRS-343 is a first-in-class bispecific antibody-Anticalin fusion protein targeting the oncogenic tumor antigen HER2 and the costimulatory immune receptor 4-1BB on T and other immune cells. Here, we report the results of a phase 1 single-agent dose escalation trial in patients with HER2+ solid tumors. Methods PRS-343 has been evaluated in sequential dose cohorts from 0.0005 to 8 mg/kg i.v. Doses were administered Q3W and the 8 mg/kg dose was also given Q2W. An accelerated titration design was utilized for the initial dose escalation followed by a modified 3+3 design and the option to back-fill cohorts. Dose-limiting toxicities (DLTs) were reported during the first cycle of each schedule. The primary study objectives include the safety profile and RP2D of PRS-343. Secondary objectives include ORR and DCR, PD biomarker response and PK profile. PD response was assessed in tumor biopsies (CD8+ T cell IHC) pre- and post- PRS-343 treatment. Results 51 patients (median age 61.2 years, 61% female, 82% caucasian, 57% with more than three lines of prior therapy) with a variety of solid tumor indications [gastric/GEJ (n=19); BC (n=12); gynecological cancer (n=6); CRC (n=5); BTC (n=4); UC (n=2); melanoma, pancreatic and salivary duct (n=1 each)] have been treated with PRS-343. Based on pharmacokinetic analyses and observed kinetics of the CD8+ T cell expansion post-treatment, the low end of the active dose range is considered 2.5 mg/kg. 19 patients treated at active dose levels before the data cut-off on 09-06-2019 were evaluable for response [DCR 58% (11% confirmed PR) as per RECIST 1.1]. At the active doses, we observed significant and pronounced post-treatment expansion of CD8+ T cells particularly in the tumor nests, consistent with the MoA of PRS-343, while there was no increase in the doses below 2.5 mg/kg. The post-treatment expansion of CD8+ T cells was more pronounced in patients with a confirmed PR or prolonged SD. PRS-343 was very well tolerated, with no SAEs reported. The most frequent TRAEs were fatigue (9%), chills (6%) and diarrhea (5%) of mild to moderate severity. None qualified as a DLT. Conclusions PRS-343 is the first molecule of its kind to demonstrate encouraging evidence of safety and clinical benefit with a correlative PD effect in a heavily pre-treated population. These initial data suggest that PRS-343, the first 4-1BB bispecific to enter clinical development, merits further investigation in clinical trials. Trial Registration NCT03330561

TPS8071 Background: CD47 is an innate immune checkpoint that binds signal regulatory protein alpha (SIRPα) and delivers a "don’t eat me" signal to suppress macrophage phagocytosis. TTI-622 is a fusion protein consisting of the CD47-binding domain of human SIRPα linked to the Fc region of human IgG4. It is designed to enhance phagocytosis and antitumor activity by preventing CD47 from delivering its inhibitory signal as well as generating a moderate pro-phagocytic signal via IgG4 Fc. CD47 is significantly increased in multiple myeloma (MM) bone marrow mononuclear cells and expression inversely correlates with survival in patients. Relapsed/Refractory (R/R) MM shows particularly high expression of CD47. Preclinical studies demonstrate that the addition of proteasome inhibitors to CD47 blockade significantly increases phagocytosis of MM cells in vitro and anti-myeloma activity in vivo. The ongoing phase 1a part of this study has been previously described. The phase 1b part of the study will determine the safety and efficacy of TTI-622 when given as monotherapy or in combination with selected approved anticancer treatments in patients with hematological malignancies where new treatments with novel mechanism of action are needed. Here we describe 5 RRMM cohorts within phase 1b of the study. Methods: TTI-622-01 is a multi-center Phase 1a/1b study. Phase 1a was designed to determine the MTD, pharmacokinetics (PK), pharmacodynamics, and preliminary antitumor activity of QW, Q2W, and Q3W single-agent TTI-622 in R/R lymphoma using a 3+3 dose escalation schema. Phase 1b, ongoing, will determine the safety and recommended dose of TTI-622 to be given as single agent and in combination with carfilzomib + dexamethasone (Kd) in RRMM and will evaluate the preliminary efficacy. Secondary objectives are to further characterize the safety, PK and immunogenicity of TTI-622 when combined with Kd. Patients will be enrolled in 5 separate cohorts: 3 cohorts will explore different doses and administration schedules of TTI-622 combined with the approved dose of Kd; 2 cohorts will explore different doses of TTI-622 monotherapy. Cohorts will be opened in a staggered manner. In each cohort 3 patients will be dosed and followed for 28 days (21 days in the monotherapy) before expanding enrolment to approximately an additional 27 patients. Key eligibility criteria include: relapse or progression following ≥3 prior lines of therapy (including a proteasome inhibitor, an immunomodulatory drug, and an anti-CD38 antibody), carfilzomib-refractory progressive and measurable disease per IMWG at study entry; age ≥18 years; ECOG performance status ≤2; adequate organ functions; no known CNS involvement; no prior anti-CD47 or anti-SIRPα therapy. Patient recruitment is planned or ongoing at 40 sites worldwide. Clinical trial information: NCT03530683.

TPS7595 Background: CD47 is an innate immune checkpoint that binds signal regulatory protein alpha (SIRPα) and delivers a "don’t eat me" signal to suppress macrophage phagocytosis. Overexpression of CD47 on cancer cells serves as a mechanism of immune surveillance evasion, and is associated with poor prognosis in both hematologic and solid malignancies. TTI-622 is a fusion protein consisting of the CD47-binding domain of human SIRPα linked to the Fc region of human IgG4. It is designed to enhance phagocytosis and antitumor activity by preventing CD47 from delivering its inhibitory signal as well as generating a moderate pro-phagocytic signal via IgG4 Fc. Importantly, unlike many CD47-blocking agents, TTI-622 does not bind to human red blood cells. Preclinical studies demonstrate that TTI-622 induces macrophage-mediated phagocytosis of different malignant cell lines, including DLBCL cells, decreases tumor growth and improves survival in a DLBCL xenograft tumor model. Anti-CD47 antibody enhances rituximab stimulated macrophage-mediated phagocytosis of non-GCB DLBCL cell lines (Bouwstra et al, Cancer Immunol Res. 2019). The ongoing phase 1a part of this study has been previously described. Here we describe 2 cohorts within the phase 1b part of the study that are intended to determine the safety and preliminary efficacy of TTI-622 when given in combination with anti-CD20 targeting agent in patients with CD20+ relapsed/refractory (RR) DLBCL. Methods: TTI-622-01 is a multi-center Phase 1a/1b study. Phase 1a was designed to determine the MTD, pharmacokinetics (PK), pharmacodynamics, and preliminary antitumor activity of QW, Q2W, and Q3W single-agent TTI-622 in R/R lymphoma using a 3+3 dose escalation schema. Phase 1b, ongoing, will determine the safety, recommended dose and preliminary efficacy of TTI-622 in combination with select approved anticancer treatments for patients with hematological malignancies including, but not limited to anti-CD20 therapy in patients with CD20+ RR DLBCL. Secondary objectives are to further characterize safety, PK and immunogenicity of TTI-622 when combined with approved therapies. Patients will be enrolled in 2 cohorts exploring different doses of TTI-622 in combination with anti-CD20 therapy. Cohorts will open in a staggered manner. In each cohort 3 patients will be dosed and followed for 28 days before expanding enrolment to additional 27 patients per cohort. Key eligibility criteria include: age ≥18 years; relapsed and/or refractory disease after ≥1 prior line of therapy; not eligible for or have progressed after high dose chemotherapy (HDT)/auto-SCT; ≥1 site of measurable disease (Lugano 2014 classification); ECOG PS ≤2; adequate organ functions, no known CNS involvement; no prior anti-CD47 or anti-SIRPα therapy. Patient recruitment is planned or ongoing at 40 sites worldwide. Clinical trial information: NCT03530683.

TPS11593 Background: Doxorubicin is a standard of care agent for patients with advanced soft tissue sarcoma, with a response rate of around 15%, progression-free survival of 5-7 months and cumulative cardiac toxicity that limits its use. TTI-621 is a recombinant soluble fusion protein that combines the N-terminal portion of human SIRPα (the binding domain for CD47) with the Fc region of human IgG1, generating a decoy receptor for CD47 on the surface of tumor cells that both over-rides CD47-mediated inhibition of phagocytosis and provides a pro-phagocytic stimulation. Many solid tumors express high levels of CD47 which is associated with poor prognosis, thought to be the result of CD47-mediated inhibition of macrophage phagocytosis and escape of immune-mediated clearance. Interruption of the CD47-SIRPα signaling pathway using monoclonal antibodies to CD47 has shown anti-tumor activity in animal models and in some early clinical trials. The combination of doxorubicin with CD47-targeted antibodies results in enhanced anti-tumor activity and increased macrophage-mediated cell killing in animal models and macrophage-mediated phagocytosis of cancer cell lines in vitro, suggesting that combining TTI-621 with doxorubicin might be more effective than doxorubicin alone in tumor types that express CD47 and have high numbers of macrophages, such as LMS. Thus, a Phase 1/2 study was initiated to evaluate this combination in patients with advanced soft tissue sarcoma, including LMS. Methods: TTI-621-03 is a Phase 1/2, open-label study of TTI-621 in combination with doxorubicin in patients with anthracycline-naïve disease. The Phase 1 dose escalation evaluates doses of TTI-621 (0.2 to 2.0 mg/kg) in combination with doxorubicin at 75 mg/m2 in patients with high-grade soft tissue sarcomas. Expansion cohorts will evaluate TTI-621 (0.2 and 2.0 mg/kg) with doxorubicin in patients with LMS, with pathology confirmed at a central laboratory. The primary goals of this study are evaluation of safety of TTI-621 administered in combination with standard-of-care doxorubicin and to further evaluate clinical activity (ORR, PFS, OS), safety, PK and patient-reported quality of life in the LMS subpopulation. The dose escalation portion of the study has been completed without DLT. Enrollment to the expansion portion of the study is underway. Clinical trial information: NCT04996004.

Background CD47 is an innate immune checkpoint that binds signal regulatory protein alpha (SIRPα) and delivers a "don't eat me" signal to suppress macrophage phagocytosis. Overexpression of CD47 serves as a mechanism of immune surveillance evasion, and is associated with poor prognosis in both hematologic and solid malignancies. TTI-622 is a fusion protein consisting of the CD47-binding domain of human SIRPα linked to the Fc region of human IgG4. It is designed to enhance phagocytosis and antitumor activity by preventing CD47 from delivering its inhibitory signal as well as generating a moderate pro-phagocytic signal via IgG4 Fc. Importantly, unlike many CD47-blocking agents, TTI-622 does not bind to human red blood cells. Methods This is an ongoing multicenter, Phase 1a/1b dose-escalation and expansion trial of TTI-622 (NCT03530683). Based on a modified 3+3 scheme, dose escalation proceeded through 8 dose levels ranging from 0.05 to 18 mg/kg weekly dosing in patients with refractory or relapsed (r/r) lymphomas. Testing of every two and three week schedules of single agent TTI-622 at doses up to 24 mg/kg is ongoing. Safety monitoring includes clinical laboratories and assessments of adverse events (AEs) based on CTCAE v 4.03. Results As of April 12, 2021, 42 patients (18M/24F) with a median age of 67 years (range 24-86) have received dose levels of 0.05−18 mg/kg weekly TTI-622. Lymphoma histologies enrolled include diffuse large B-cell lymphoma (DLBCL; n=19), cutaneous T-cell lymphoma - mycosis fungoides (CTCL-MF; n=6), peripheral T-cell lymphoma (PTCL; n=6), Hodgkin lymphoma (HL; n=5), and follicular lymphoma (FL; n=4). Additional histologies with single patients only accounted for the remaining 2 patients. Disease stages at entry have been III or IV in 38 patients and median prior systemic therapies of 3 (range 1-9) have been received, including CAR-T and HSCT in 9 and 10 patients, respectively. One additional patient with Erdheim-Chester disease initially diagnosed as lymphoma is included in the safety analysis only. Treatment-related AEs have occurred in 20 (47%) patients; most AEs have been Grade 1 or 2 and reversible. The most frequent treatment-related AEs include thrombocytopenia (n=9, 21%), neutropenia (n=5, 12%), and anemia and fatigue (n=4 each, 9%). Related adverse events of Grade ≥ 3 intensity include thrombocytopenia (n=2, 5%; 1 each Grade 3 & 4), neutropenia (n=4, 9%; all Grade 3), and anemia (n=1, 2%; Grade 3). These Grade 3 and 4 hematologic events occurred in dose levels ranging from 0.8 to 18 mg/kg without apparent dose relationship. Mild to moderate platelet decreases seen in the majority of patients generally occurred on dosing days and recovered quickly to baseline levels. Preliminary PK results suggest dose-dependent increases in exposure following both single and repeated TTI-622 infusions. A total of 27 patients were response-evaluable at dose levels ≥0.8 mg/kg at the time of the data-cut. Objective responses have been achieved in 9 patients, including 2 complete responses (CR) - 1 in DLBCL (0.8 mg/kg) and 1 in CTCL (18 mg/kg) - and 7 partial responses (PR) - 2 in CTCL (both 8 mg/kg), 2 in PTCL (2 and 12 mg/kg), 2 in DLBCL (4 and 18 mg/kg), and 1 in FL (8 mg/kg). Initial responses were achieved at the first disease assessment (week 8) in all 9 responders. In the dose range of 0.8-18 mg/kg, objective responses occurred in 33% (9/27) of response-evaluable patients. At the time of the data cut-off 4 responders were active on treatment; both patients with CR, ongoing 22+ months (0.8 mg/kg) and 12 weeks on an every three week dosing schedule (18 mg/kg). Two patients with PR were ongoing 18 weeks (12 mg/kg) and 11 weeks (18 mg/kg). Conclusions Results to date in patients with r/r lymphomas indicate that weekly doses of single agent TTI-622 up to 18 mg/kg are well tolerated. TTI-622 has shown activity in r/r lymphoma with objective responses across a broad dose range (0.8-18 mg/kg), in highly pre-treated patients, across multiple histologies, and with onset of action consistently observed at the first response assessment at Week 8. The study is ongoing evaluating single agent TTI-622 in every two and three week schedules. Updated data including additional patients will be presented at the conference. Based on these results demonstrating promising single-agent activity as well as good tolerability, TTI-622 is currently being investigated in combination regimens in a range of hematologic malignancies. Disclosures Patel: Xencor: Research Funding; Velos Bio: Research Funding; Trillium Therapeutics: Research Funding; TG Therapeutics: Consultancy, Speakers Bureau; Sunesis Pharmaceuticals: Research Funding; Pharmacyclics/Janssen: Consultancy, Research Funding, Speakers Bureau; Morphosys: Consultancy; Millenium/Takeda: Research Funding; MEI Pharma: Consultancy, Research Funding; Kite: Consultancy, Research Funding, Speakers Bureau; Juno Pharmaceuticals: Consultancy; Genentech/Roche: Consultancy, Research Funding, Speakers Bureau; Fate Therapeutics: Research Funding; Curis, Inc: Research Funding; Celgene: Consultancy, Research Funding, Speakers Bureau; Bristol Myers Squibb: Consultancy, Research Funding, Speakers Bureau; BeiGene: Consultancy; AstraZeneca: Consultancy, Research Funding, Speakers Bureau; Aptevo Therapeutics: Research Funding; Abbvie: Consultancy. Zonder: Amgen: Consultancy; BMS: Consultancy, Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy; Caelum Biosciences: Consultancy; Intellia: Consultancy; Regeneron: Consultancy; Alnylam: Consultancy. Lesokhin: pfizer: Consultancy, Research Funding; Genetech: Research Funding; Janssen: Honoraria, Research Funding; Iteos: Consultancy; bristol myers squibb: Research Funding; Serametrix, Inc: Patents & Royalties; Trillium Therapeutics: Consultancy; Behringer Ingelheim: Honoraria. von Keudell: Merck: Consultancy, Honoraria; Pharmacyclics: Consultancy, Honoraria; Merck: Research Funding; Incyte: Consultancy, Honoraria; AbbVie: Research Funding; BMS: Research Funding; Janssen: Research Funding. Lai: Macrogenics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astellas: Speakers Bureau; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz Pharma: Speakers Bureau; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees. Ramchandren: curis: Research Funding; seattle genetics: Consultancy, Research Funding; MERCK: Consultancy, Research Funding; pharmacyclics: Consultancy, Research Funding; BMS: Consultancy; Trillium: Research Funding. Catalano: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Lin: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Uger: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Petrova: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Molloy: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Bruns: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company.

Background CD47 is an innate immune checkpoint that binds signal regulatory protein alpha (SIRPα) and delivers a "don't eat me" signal to suppress macrophage phagocytosis. Overexpression of CD47 can allow tumor cells to escape immune surveillance. TTI-621 (SIRPαFc) is a fusion protein consisting of the CD47 binding domain of human SIRPα linked to the Fc region of human IgG1, designed to enhance phagocytosis and antitumor activity by blocking the CD47-SIRPα interaction between malignant cells and macrophages, and engaging Fcγ receptors. Here we report updates from the dose optimization part of the first-in-human study of TTI-621 (NCT02663518), testing dose levels between 0.5-2.0 mg/kg in patients with cutaneous T-cell lymphoma (CTCL). Methods This study has been conducted in 4 parts. Part 1 tested increasing weekly intravenous doses of TTI-621 based on 3+3 escalation. The maximum tolerated dose was initially determined to be 0.2 mg/kg based on dose limiting toxicity (DLT) of thrombocytopenia [defined as Grade (Gr) 4 of any duration]. Expanded testing followed in patients with hematologic malignancies. In Part 2, most patients received 0.2 mg/kg; however, based on investigator discretion, a subset of patients received escalating doses up to 0.5 mg/kg. In Part 3, patients with T-cell lymphomas received stepwise dose escalations from 0.2 to 0.5 mg/kg over the first 5−8 weeks. Part 4 (dose optimization) of this study, is currently ongoing with weekly TTI-621 treatment escalating in a standard 3+3 manner through 5 planned dose levels including 0.5, 0.7, 1, 1.4, and 2 mg/kg. Dose optimization is being assessed in patients with CTCL. The DLT criteria was modified to require Gr 4 thrombocytopenia lasting >72 hours. Safety monitoring includes weekly clinical laboratories and assessments of adverse events (AEs) per CTCAE v 4.03. Blood samples are obtained for pharmacokinetics and disease assessments are performed per Olsen's criteria. Results In Parts 1−3 (n=214), the most common related AEs were infusion-related reaction (IRR, 43%; 3% Gr ≥3), thrombocytopenia (30%; 22% Gr ≥3), chills (22%; 0% Gr ≥3), and fatigue (16%; 1% Gr ≥3). Objective responses to single agent TTI-621 were achieved in 14/71 (20%) NHL pts including CTCL (n=42, 1 CR, 7 PRs), PTCL (n=22, 2 CRs, 2 PRs) and DLBCL (n=7, 1 CR, 1 PR). In Part 4 as of April 12, 2021, 24 patients (17M/7F, median age 65 years) have enrolled into the 5 dose cohorts including 9 patients in the 2.0 mg/kg dose level. CTCL subtypes enrolled include mycosis fungoides (MF, n=18) and Sézary syndrome (SS, n=6). Disease stage was advanced (≥IIB) in 16 (67%) patients and a median of 3 (range 1−12) prior systemic therapies were received. Related AEs occurred in 19 (79%; 33% Gr ≥3) patients including infusion-related reaction (IRR, 50%; 13% Gr ≥3), thrombocytopenia (33%; 25% Gr ≥3), and neutropenia and headache, (13%, 0% Gr ≥3, each). Thrombocytopenia generally occurred on dosing days, and typically recovered within 2-4 days. A total of 15 IRRs have occurred in 12 (50%) patients at all doses levels. Most IRRs occurred during initial infusions only and typically resolved within the day of occurrence. The occurrence of Gr 3 IRRs prompted the addition of corticosteroids to the pre-medication regimen which largely prevent their occurrence. Aside from IRRs and thrombocytopenia which was manageable, AEs were predominantly Gr ≤2. Pharmacokinetic results reveal continued dose-dependent increases in exposure. Objective responses have been observed in 4 of 20 (20%) evaluable patients to date, including 3 partial responses in 14 patients with MF and 1 complete response in 6 patients with SS. Treatment is ongoing in the patient who achieved CR (10+ months) and in 2 of 3 patients who achieved PR (3 and 4 months). A third patient who achieved PR elected to discontinue study treatment at 5 months to pursue allogeneic stem and progenitor cell transplantation. Conclusions Preliminary results from dose optimization testing indicate that weekly infusions of TTI-621 up to 2 mg/kg are generally well tolerated. In Part 4, an overall response rate of 20% has been observed thus far in patients with CTCL. Testing of TTI-621 in alternative dosing schedules is in progress. With demonstrated good tolerability and robust single agent antitumor activity in heavily pre-treated patients, additional testing of TTI-621 beyond relapsed/refractory lymphoma has started. Disclosures Horwitz: Affimed: Research Funding; ADC Therapeutics, Affimed, Aileron, Celgene, Daiichi Sankyo, Forty Seven, Inc., Kyowa Hakko Kirin, Millennium /Takeda, Seattle Genetics, Trillium Therapeutics, and Verastem/SecuraBio.: Consultancy, Research Funding; Acrotech Biopharma, Affimed, ADC Therapeutics, Astex, Merck, Portola Pharma, C4 Therapeutics, Celgene, Janssen, Kura Oncology, Kyowa Hakko Kirin, Myeloid Therapeutics, ONO Pharmaceuticals, Seattle Genetics, Shoreline Biosciences, Inc, Takeda, Trillium Th: Consultancy; Aileron: Research Funding; Celgene: Research Funding; C4 Therapeutics: Consultancy; Crispr Therapeutics: Research Funding; Daiichi Sankyo: Research Funding; Forty Seven, Inc.: Research Funding; Kura Oncology: Consultancy; Kyowa Hakko Kirin: Consultancy, Research Funding; Millennium/Takeda: Research Funding; Myeloid Therapeutics: Consultancy; ONO Pharmaceuticals: Consultancy; Seattle Genetics: Consultancy, Research Funding; Secura Bio: Consultancy; Shoreline Biosciences, Inc.: Consultancy; Takeda: Consultancy; Trillium Therapeutics: Consultancy, Research Funding; Tubulis: Consultancy; Verastem/Securabio: Research Funding. Foran: pfizer: Honoraria; novartis: Honoraria; servier: Honoraria; bms: Honoraria; revolution medicine: Honoraria; taiho: Honoraria; syros: Honoraria; sanofi aventis: Honoraria; certara: Honoraria; gamida: Honoraria; OncLive: Honoraria; abbvie: Research Funding; boehringer ingelheim: Research Funding; takeda: Research Funding; trillium: Research Funding; aptose: Research Funding; actinium: Research Funding; kura: Research Funding; h3bioscience: Research Funding; aprea: Research Funding; sellas: Research Funding; stemline: Research Funding. Lue: Epizyme: Consultancy; TG Therapeutics: Consultancy; Kymera Therapeutics: Research Funding; AstraZeneca: Speakers Bureau; Kura Oncology: Consultancy. Sawas: Affimed: Research Funding; Roche: Current equity holder in publicly-traded company; Flat Iron Health: Current Employment; Seattle Genetics: Honoraria; Acrotech: Honoraria; Daiichi-Sankyo: Speakers Bureau; Seattle Genetics: Speakers Bureau; Gilead: Speakers Bureau. Feldman: Alexion, AstraZeneca Rare Disease: Honoraria, Other: Study investigator. Sokol: Kyowa-Kirin: Membership on an entity's Board of Directors or advisory committees; Dren Bio: Membership on an entity's Board of Directors or advisory committees. Mei: Janssen: Honoraria; EUSA: Honoraria; TG Therapeutics: Research Funding; Epizyme: Research Funding; BMS: Research Funding; Morphosys: Research Funding; Beigene: Research Funding. Flinn: AbbVie: Consultancy, Other: All Consultancy and Research Funding payments made to Sarah Cannon Research Institute, Research Funding; AstraZeneca: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; BeiGene: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Genentech: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Gilead Sciences: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Great Point Partners: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Iksuda Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Janssen: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Juno Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Kite, a Gilead Company: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; MorphoSys: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Nurix Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Pharmacyclics LLC, an AbbVie Company: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Roche: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Seagen: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Takeda: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; TG Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Unum Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Verastem: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Yingli Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Acerta Pharma: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Agios: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; ArQule: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Calithera Biosciences: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Celgene: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Constellation Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Curis: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Forma Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Forty Seven: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; IGM Biosciences: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Incyte: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Infinity Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Karyopharm Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Loxo: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Merck: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Novartis: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Pfizer: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Portola Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Rhizen Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Teva: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Trillium Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Triphase Research & Development Corp.: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Century Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Hutchison MediPharma: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Vincerx Pharma: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Sarah Cannon Research Institute: Current Employment; Servier Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Yingli Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Seagen: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Servier Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Unum Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute, Research Funding; Johnson & Johnson: Current holder of individual stocks in a privately-held company; Seattle Genetics: Research Funding. Villa: Janssen: Honoraria; Roche: Honoraria; Lundbeck: Honoraria; Celgene: Honoraria; Seattle Genetics: Honoraria; AbbVie: Honoraria; AstraZeneca: Honoraria; Gilead: Honoraria; NanoString Technologies: Honoraria. Percival: Pfizer: Research Funding; Abbvie: Research Funding; Biosight: Research Funding; BMS/Celgene: Research Funding; Cardiff Oncology: Research Funding; Glycomimetics: Research Funding; Nohla Therapeutics: Research Funding; Oscotec: Research Funding; Trillium: Research Funding. Savage: Seattle Genetics: Consultancy, Honoraria; BMS: Consultancy, Honoraria, Other: Institutional clinical trial funding; Merck: Consultancy, Honoraria, Other: Institutional clinical trial funding; AbbVie: Consultancy, Honoraria; Astra-Zeneca: Consultancy, Honoraria; Servier: Consultancy, Honoraria; Roche: Research Funding; Takeda: Other: Institutional clinical trial funding; Beigene: Other: Institutional clinical trial funding; Genentech: Research Funding. Diefenbach: Genentech, Inc./ F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria, Research Funding; Merck Sharp & Dohme: Consultancy, Honoraria, Research Funding; Morphosys: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; MEI: Consultancy, Research Funding; Gilead: Current equity holder in publicly-traded company; IMab: Research Funding; Celgene: Research Funding; Trillium: Research Funding; Incyte: Research Funding; AbbVie: Research Funding; Perlmutter Cancer Center at NYU Langone Health: Current Employment; IGM Biosciences: Research Funding. Kim: Kyowa Kirin: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Innate: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Corvus: Membership on an entity's Board of Directors or advisory committees, Research Funding; Trillium: Research Funding; Galderma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Elorac: Research Funding; Portola: Membership on an entity's Board of Directors or advisory committees, Research Funding; Soligenix: Research Funding; Eisai: Research Funding; CRISPR: Research Funding; Regeneron: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Mundipharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; Secura Bio: Honoraria, Membership on an entity's Board of Directors or advisory committees; Alexion, AstraZeneca Rare Disease: Other: Study investigator; Merck: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Horizon: Research Funding. Lin: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Catalano: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Petrova: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Uger: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Molloy: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Large: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Bruns: Trillium Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Ansell: Bristol Myers Squibb, ADC Therapeutics, Seattle Genetics, Regeneron, Affimed, AI Therapeutics, Pfizer, Trillium and Takeda: Research Funding.

AZD1402/PRS-060 is a novel inhaled Anticalin® molecule antagonizing IL-4Ra. A multiple ascending dose clinical study (NCT03574805) was conducted in mild asthmatics (fractional exhaled nitric oxide (FeNO) levels ≥ 35ppb), to assess the safety, tolerability, pharmacokinetics and pulmonary and systemic IL-4Ra target engagement of AZD1402/PRS-060. The drug candidate was administered by nebulized oral inhalation at delivered doses between 2 and 20mg, twice daily for 9 days with one dose on day 10. All doses of AZD1402/PRS-060 were found to be safe and well tolerated; no serious adverse events were observed. Lung target engagement was determined by reduction of FeNO levels and systemic target engagement was determined ex vivo by inhibition of IL-4-stimulated signal transducer and activator of transcription 6 (STAT6) phosphorylation in whole blood. Significant and pronounced (≥25%) inhibition of FeNO was observed at all doses, including the 2mg delivered dose, where no systemic target engagement and minimal systemic exposure was observed. This suggests that local target engagement by the drug is sufficient to reduce airway inflammation, as measured by FeNO. The onset of FeNO reduction was rapid (after a single dose) and the maximum effect (day 4-5) vs placebo was sustained until dosing completion. Systemic target engagement was dose-dependent and closely aligned with systemic exposure of the drug. Pulmonary target engagement as shown by a substantial reduction in FeNO and the overall profile of the drug demonstrates its suitability for continued development as an inhaled therapy for asthma.

AZD1402/PRS-060 is a novel inhaled Anticalin® molecule that antagonizes the IL-4 receptor alpha (IL-4Ra). A first-in-human study in healthy subjects was conducted to assess the safety, tolerability and pharmacokinetics (PK) of inhaled single ascending doses and intravenous infusion (IV) doses. In this study (NCT03384290), the drug was administered by nebulized oral inhalation at delivered doses between 0.1mg and 160mg (corresponding to device doses between 0.25mg and 400mg) or intravenous infusion (IV) at 1mg and 2mg. AZD1402/PRS-060 was found to be safe and well tolerated at all dose levels via both routes of administration and no serious adverse events were reported and no anti-drug antibodies were detected. Systemic, dose-dependent exposure was observed after inhaled delivered doses ≥8mg. Inhaled PK showed slow and prolonged absorption into the systemic circulation. Clearance and volume of distribution values after IV doses were indicative of clearance by renal filtration and a low tissue distribution. Target engagement, as assessed by inhibition of systemic STAT6 phosphorylation was dose-dependent and closely aligned with systemic exposure of the drug. Near complete and sustained inhibition of pSTAT6 was observed at higher inhaled doses. In the ongoing MAD study in mild asthmatics (NCT03574805), systemic target engagement (pSTAT6) will be compared with lung target engagement, assessed by measuring fractional nitric oxide in exhaled breath. This will help set inhaled doses for future studies of this first-in-class inhaled Anticalin molecule. The overall profile of the drug demonstrates its suitability for development as an inhaled drug for the treatment of asthma.

New drugs for the treatment of multiple myeloma (MM) comprise immunomodulatory substances such as lenalidomide and related compounds. While lenalidomide has found its way into first-line treatment as well as into relapse therapy, little is known about lenalidomide effects on normal hematopoietic stem and progenitor cells (HSPCs). In this study, we investigated whether HSPCs are influenced by lenalidomide on a phenotypic, functional and gene expression level. For that purpose, samples from patients with MM were obtained who underwent equivalent first-line treatment including induction therapy, cytotoxic stem cell mobilization and high-dose melphalan therapy followed by autologous blood stem cell transplantation and a subsequent uniform lenalidomide consolidation treatment within a prospective clinical trial. We found that after six months of lenalidomide therapy, the number of CD34(+) HSPCs decreased. Additionally, lenalidomide affects the numerical composition of hematopoietic cells in the bone marrow while it does not affect long-term HSPC proliferation in vitro. We found a significant amplification of fetal hemoglobin (HbF) expression on a transcriptional level and can confirm a stimulated erythropoiesis on a phenotypic level. These effects were accompanied by silencing of the TGF-β signaling pathway on the gene expression and protein level that is known to be amplified in active MM. However, these pleiotropic effects gave no evidence for mutagenic potential. In conclusion, lenalidomide does not exert long-term effects on proliferation of HSPCs but instead promotes erythropoiesis by shifting hemoglobin expression toward HbF and by silencing the TGF-β signaling pathway.

Bcl-2/IgH rearrangements can be quantified in follicular lymphoma (FL) from peripheral blood (PB) by polymerase chain reaction (PCR). The prognostic value of Bcl-2/IgH levels in FL remains controversial. We therefore prospectively studied PB Bcl-2/IgH levels from 173 first-line FL patients who were consecutively enrolled, randomized, and treated within the multicenter phase 3 clinical trial NHL1-2003 comparing bendamustine-rituximab (B-R) with rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone. From April 2005 to August 2008, 783 pre- and posttreatment PB samples were quantified by quantitative PCR. At inclusion, 114 patients (66%) tested positive and 59 (34%) were negative for Bcl-2/IgH. High pretreatment Bcl-2/IgH levels had an adverse effect on progression-free survival (PFS) compared with intermediate or low levels (high vs intermediate: hazard [HR], 4.28; 95% confidence interval [CI], 1.70-10.77; P = .002; high vs low: HR, 3.02; 95% CI, 1.55-5.86; P = .001). No PFS difference between treatment arms was observed in Bcl-2/IgH-positive patients. A positive posttreatment Bcl-2/IgH status was associated with shorter PFS (8.7 months vs not reached; HR, 3.15; 95% CI, 1.51-6.58; P = .002). By multivariate analysis, the pretreatment Bcl-2/IgH level was the strongest predictor for PFS. Our data suggest that pre- and posttreatment Bcl-2/IgH levels from PB have significant prognostic value for PFS in FL patients receiving first-line immunochemotherapy. This trial was registered at www.clinicaltrials.gov as #NCT00991211 and at the German Federal Institute for Drugs and Medical Devices as #BfArM-4021335.

Anticancer chemotherapy drugs challenge hematopoietic tissues to regenerate but commonly produce long-term sequelae. Chemotherapy-induced deficits in hematopoietic stem or stromal cell function have been described, but the mechanisms mediating hematopoietic dysfunction remain unclear. Administration of multiple cycles of cisplatin chemotherapy causes substantial sensory neuropathy. Here we demonstrate that chemotherapy-induced nerve injury in the bone marrow of mice is a crucial lesion impairing hematopoietic regeneration. Using pharmacological and genetic models, we show that the selective loss of adrenergic innervation in the bone marrow alters its regeneration after genotoxic insult. Sympathetic nerves in the marrow promote the survival of constituents of the stem cell niche that initiate recovery. Neuroprotection by deletion of Trp53 in sympathetic neurons or neuroregeneration by administration of 4-methylcatechol or glial-derived neurotrophic factor (GDNF) promotes hematopoietic recovery. These results demonstrate the potential benefit of adrenergic nerve protection for shielding hematopoietic niches from injury.

Bleeding complications are a significant clinical problem in patients with myelodysplastic syndromes even at sufficient platelet counts (>50,000/μl). However, the underlying pathology of this hemorrhagic diathesis is still unknown. Here, we analyzed the platelet proteome of patients with myelodysplastic syndromes by quantitative two-dimensional difference gel electrophoresis followed by mass spectrometric protein identification. Proteins identified with lower concentrations, such as Talin-1, Vinculin, Myosin-9, Filmain-A, and Actin play critical roles in integrin αIIbβ3 signaling and thus platelet aggregation. Despite normal agonist receptor expression, calcium flux, and granule release upon activation, the activation capacity of integrin αIIbβ3 was diminished in myelodysplastic syndrome platelets. Förster resonance energy transfer analysis showed a reduced co-localization of Talin-1 to the integrin's β3-subunit, which is required for receptor activation and fibrinogen binding. In addition, platelet spreading on immobilized fibrinogen was incomplete, and platelet aggregation assays confirmed a general defect in integrin-dependent platelet aggregation in patients with myelodysplastic syndromes. Our data provide novel aspects on the molecular pathology of impaired platelet function in myelodysplastic syndromes and suggest a mechanism of defective integrin αIIbβ3 signaling that may contribute to the hemorrhagic diathesis observed in these patients.

Ineffective hematopoiesis is a major characteristic of myelodysplastic syndromes (MDS) causing relevant morbidity and mortality. Mesenchymal stromal cells (MSC) have been shown to physiologically support hematopoiesis, but their contribution to the pathogenesis of MDS remains elusive. We show that MSC from patients across all MDS subtypes (n=106) exhibit significantly reduced growth and proliferative capacities accompanied by premature replicative senescence. Osteogenic differentiation was significantly reduced in MDS-derived MSC, indicated by cytochemical stainings and reduced expressions of Osterix and Osteocalcin. This was associated with specific methylation patterns that clearly separated MDS-MSC from healthy controls and showed a strong enrichment for biological processes associated with cellular phenotypes and transcriptional regulation. Furthermore, in MDS-MSC, we detected altered expression of key molecules involved in the interaction with hematopoietic stem and progenitor cells (HSPC), in particular Osteopontin, Jagged1, Kit-ligand and Angiopoietin as well as several chemokines. Functionally, this translated into a significantly diminished ability of MDS-derived MSC to support CD34+ HSPC in long-term culture-initiating cell assays associated with a reduced cell cycle activity. Taken together, our comprehensive analysis shows that MSC from all MDS subtypes are structurally, epigenetically and functionally altered, which leads to impaired stromal support and seems to contribute to deficient hematopoiesis in MDS.

Patients suffering from high-risk myelodysplastic syndrome (MDS) or acute myelogenous leukemia (AML) secondary to MDS (sAML) are characterized by poor response to conventional cytotoxic chemotherapy. The purpose of our prospective single-center study was to examine the safety and efficacy of an allogeneic hematopoietic stem cell transplantation (HSCT) following a sequential conditioning regimen as first-line therapy for previously untreated patients with high-risk MDS or sAML. Between November 2003 and June 2010, 30 patients (20 high-risk MDS, 10 sAML) received fludarabine (4 × 30 mg/m(2)), amsacrine (4 × 100 mg/m(2)), and Ara-C (4 × 2 g/m(2), FLAMSA). After 2 to 3 days of rest, patients received high-dose melphalan alone (200 mg/m(2) for patients with an age50 years, 150 mg/m(2) for patients with an age between 50 and 60 years, and 100 mg/m(2) for patients with an age60 years; n = 24) or melphalan and thiotepa (10 mg/kg, Mel/Thio, n = 6). Following these high-dose conditioning regimens, a median number of 7.7 × 10(6) CD34(+) cells/kg body weight (range: 2.9 × 10(6)-17.2 × 10(6)) were transplanted from 13 related or 17 unrelated donors. Antithymocyte globulin (Fresenius 30-60 mg/kg) as well as tacrolimus and mycophenolate mofetil were used for graft-versus-host disease (GVHD) prophylaxis. All patients except 1 with primary graft failure achieved complete remission after HSCT. After a median follow-up time of 28 months (range: 7-81), 21 patients (70%) were alive and free of disease. Overall, 4 patients relapsed. At 2 years, overall survival, event-free survival, and treatment-related mortality were 70%, 63%, and 30%, respectively. Because of undue toxicity, thiotepa is no longer part of the conditioning regimen. Our results add to the body of evidence that a FLAMSA-based sequential conditioning therapy is effective for previously untreated patients with high-risk MDS or sAML.

Secondary primary malignancies (SPM) are an emerging issue in patients with multiple myeloma (MM) since the lenalidomide arm of the French IFM 2005-02 trial has been closed as a consequence of a higher incidence of SPM in patients who had received lenalidomide as maintenance treatment compared to the patients in the placebo arm. To evaluate the incidence of SPM in the group of patients, who were treated with high-dose therapy (HDT) followed by autologous peripheral blood stem cell transplantation (PBSCT), we retrospectively looked at a homogeneous group of 313 consecutive patients, who were diagnosed with MM and had received HDT and autologous PBSCT at our hospital between December 1994 and January 2009. Induction treatment consisted of conventional chemotherapy without novel agents in 95% of patients and maintenance treatment was given with interferon or thalidomide in 37% und 35% of patients, respectively. Roland Fenk, Florian Neubauer, Ingmar Bruns, Christian Saure, Thomas Schroder, Ulrich Germing, Rainer Haas and Guido Kobbe

For patients with relapsed or refractory multiple myeloma (MM) treated with a prior high-dose therapy (HDT) followed by autologous peripheral blood stem cell transplantation (PBSCT), the reapplication of HDT is a widely used salvage strategy. In this retrospective study, we report on 55 patients who were treated with salvage HDT at our institution. The conditioning regimen consisted of melphalan 200 mg/m(2) (27%), melphalan 140 mg/m(2) and busulfan 12 mg/kg body weight (40%), or melphalan 200 mg/m(2) and bortezomib 1.3 mg/m(2) (33%). Treatment-related mortality was 5% and response rates were as follows: 9% complete remission, 9% very good partial remission, 56% partial remission, 11% minimal response + stable disease, and 4% progressive disease (5% not assessable). Toxicity was moderate and the median event-free (EFS) and overall survival (OS) were 14 months and 52 months, respectively. The different conditioning regimens did not result in differences in terms of remission rates, EFS and OS, or toxicity. In multivariate analysis a duration of remission of more than 12 months after the first transplant was the only predictive factor for both EFS (p0.0001) and OS (p = 0.0001). In conclusion, salvage HDT followed by autologous PBSCT is an effective treatment option for patients with relapsed or refractory MM, while patients with an early relapse after their first transplant do not benefit from this treatment modality.

2537Background: Here we present a study combining BAY1217389 (BAY), a potent MPS-1 kinase inhibitor with a backbone chemotherapy paclitaxel. Since we expected overlapping toxicities we sought to im...

Like other somatic stem cells, hematopoietic stem cells (HSC) have the ability to either self-renew or to differentiate. They are essentially required for the hematopoietic homeostasis. In this context HSC do not only need to replenish peripheral blood cells of all lineages, but also have to keep their pool relatively constant. Since disruption of the underlying control mechanisms can lead to degeneration or expansion of the HSC-pool as it occurs after irradiation or in leukemia, it is an important concern to unveil mechanisms that govern the decision of self-renewal versus differentiation in HSC-biology. There is good evidence that certain extrinsic cues provided in a special environment, the HSC-niches, essentially take part in regulating the HSC-pool in vivo and might also be involved in leukemogenesis. Apart from that, asymmetric cell divisions seem to be another control instance in hematopoietic homeostasis. It has been shown that siblings of primitive hematopoietic cells often adopt different cell fates, and very recently we identified four proteins that segregate asymmetrically in a proportion of dividing primitive hematopoietic cells. Whether asymmetric cell division participates in leukemogenesis, remains to be investigated. However, on the example of neural stem cells of the Drosophila larvae, the neuroblasts, asymmetrically segregating molecules have been identified, i.e. the tumor suppressor protein Brat and the transcription factor Prospero, that are required to suppress self-renewal in one of the arising daughter cells and whose loss of function results in tumor formation. These findings provide an attractive model of how defects in the process of asymmetric cell divisions might transform normal HSC/HPC into leukemic cells.

Pegfilgrastim has shown to decrease the duration of severe neutropenia after conventional chemotherapy, but its use after high-dose chemotherapy and autologous blood stem cell transplantation has not been established yet. Therefore we studied the efficacy and the pharmacokinetic profile of pegfilgrastim in patients with multiple myeloma undergoing high-dose chemotherapy.In total, 21 patients received a single subcutaneous injection of 6 mg pegfilgrastim on day +1 after transplantation and pegfilgrastim plasma levels were measured daily by enzyme-linked immunosorbent assay. Clinical outcome was compared with pegfilgrastim levels of 282 plasma samples and data of a historical control group of patients without granulocyte colony-stimulating factor (G-CSF) support.Pegfilgrastim levels showed an inverse correlation (r = -0.68, p0.01) with neutrophil counts. Peak levels were reached at day +4 (94 ng/mL; range: 37-205) and were maintained until day +7 (85 ng/mL; range: 35-186). Comparison with the control group without G-CSF support showed that time to neutrophil reconstitution was significantly shorter in the pegfilgrastim group with 10 vs 15 days, respectively (p0.001). There was no correlation of pegfilgrastim levels and the duration of neutropenia, although patients with a fivefold increase in neutrophil counts the day after pegfilgrastim administration had a significantly shorter median duration of neutropenia in comparison to patients who were less susceptible to G-CSF stimulation (5 vs 7 days, p0.01).Neutrophil reconstitution after high-dose chemotherapy could be accelerated by the use of pegfilgrastim in patients with myeloma. Responsiveness of neutrophils to pegfilgrastim before neutropenia was correlated with faster neutrophil reconstitution, whereas G-CSF levels had no impact on neutrophil recovery.

BACKGROUND: Current regimens for peripheral blood progenitor cell (PBPC) mobilization in patients with multiple myeloma are based on daily subcutaneous injections of granulocyte‐colony-stimulating factor (GCSF) starting shortly after cytotoxic therapy. Recently a polyethylene glycol‐conjugated G-CSF (pegfilgrastim) was introduced that has a substantially longer t1/2 than the original formula. STUDY DESIGN AND METHODS: The use of pegfilgrastim was examined at two dose levels for PBPC mobilization in patients with Stage II or III multiple myeloma. Four days after cytotoxic therapy with cyclophosphamide (4 g/m 2 ), a single dose of either 6 mg

Purpose: The fragile histidine triad protein (FHIT) is a putative tumor suppressor in patients with lung cancer. In this study, we examined the prognostic value of FHIT expression for survival in patients with small cell lung cancer (SCLC). Experimental Design: As assessed by immunohistochemistry using formalin-fixed, paraffin-embedded tissue sections, tumors of 225 patients with SCLC were retrospectively evaluated for FHIT expression. The influence of FHIT staining intensities as well as the proportion of FHIT-positive cells within a tumor was taken into consideration for univariate and multivariate survival analysis. Results: FHIT expression was observed in 61.8% of the SCLC tumors. Lack of FHIT was significantly associated with a shorter survival time for the patients with a median of 157 ± 18 days compared with 210 ± 18 days for those patients with FHIT-positive tumors (P = 0.0061). Furthermore, the proportion of FHIT-positive cells within the tumor was related to survival. Patients with tumors of Conclusion: The presence of FHIT was correlated with a better prognosis for patients with SCLC.

We read with great interest the paper of Lopez-Otero et al.,1 in which they describe a feasible approach of using high-dose chemotherapy and autologous transplantation in patients with multiple myeloma without cryopreservation of the PBSCs. In their study, they used a G-CSF-based steady-state mobilization strategy immediately followed by a single dose of high-dose melphalan (200 mg/m2, day −1) and transplantation of the fridge-stored (+4 °C) autologous, unmanipulated PBSCs on day 0. Using this regimen they observed response and survival rates comparable to those achieved by a classical transplantation strategy using cryopreserved autografts, which has also been previously demonstrated by Carey et al. and several other groups.2, 3

In the bone marrow, hematopoietic stem cells (HSCs) lodge in specialized microenvironments that tightly control the proliferative state of HSCs to adapt to the varying needs for replenishment of blood cells while also preventing HSC exhaustion. All putative niche cells suggested thus far have a nonhematopoietic origin. Thus, it remains unclear how feedback from mature cells is conveyed to HSCs to adjust their proliferation. Here we show that megakaryocytes (MKs) can directly regulate HSC pool size in mice. Three-dimensional whole-mount imaging revealed that endogenous HSCs are frequently located adjacent to MKs in a nonrandom fashion. Selective in vivo depletion of MKs resulted in specific loss of HSC quiescence and led to a marked expansion of functional HSCs. Gene expression analyses revealed that MKs are the source of chemokine C-X-C motif ligand 4 (CXCL4, also named platelet factor 4 or PF4) in the bone marrow, and we found that CXCL4 regulates HSC cell cycle activity. CXCL4 injection into mice resulted in a reduced number of HSCs because of their increased quiescence. By contrast, Cxcl4(-/-) mice exhibited an increased number of HSCs and increased HSC proliferation. Combined use of whole-mount imaging and computational modeling was highly suggestive of a megakaryocytic niche capable of independently influencing HSC maintenance by regulating quiescence. These results indicate that a terminally differentiated cell type derived from HSCs contributes to the HSC niche, directly regulating HSC behavior.

Complete remission in a patient with relapsed angioimmunoblastic T-cell lymphoma following treatment with bevacizumab

The mechanisms mediating hematopoietic stem and progenitor cell (HSPC) mobilization by G-CSF are complex. We have found previously that G-CSF–enforced mobilization is controlled by peripheral sympathetic nerves via norepinephrine (NE) signaling. In the present study, we show that G-CSF likely alters sympathetic tone directly and that methods to increase adrenergic activity in the BM microenvironment enhance progenitor mobilization. Peripheral sympathetic nerve neurons express the G-CSF receptor and ex vivo stimulation of peripheral sympathetic nerve neurons with G-CSF reduced NE reuptake significantly, suggesting that G-CSF potentiates the sympathetic tone by increasing NE availability. Based on these data, we investigated the NE reuptake inhibitor desipramine in HSPC mobilization. Whereas desipramine did not by itself elicit circulating HSPCs, it increased G-CSF–triggered mobilization efficiency significantly and rescued mobilization in a model mimicking “poor mobilizers.” Therefore, these data suggest that blockade of NE reuptake may be a novel therapeutic target to increase stem cell yield in patients.

Multiple myeloma (MM) is a clonal plasma cell disorder frequently accompanied by hematopoietic impairment. We show that hematopoietic stem and progenitor cells (HSPCs), in particular megakaryocyte-erythrocyte progenitors, are diminished in the BM of MM patients. Genomic profiling of HSPC subsets revealed deregulations of signaling cascades, most notably TGFβ signaling, and pathways involved in cytoskeletal organization, migration, adhesion, and cell-cycle regulation in the patients. Functionally, proliferation, colony formation, and long-term self-renewal were impaired as a consequence of activated TGFβ signaling. In accordance, TGFβ levels in the BM extracellular fluid were elevated and mesenchymal stromal cells (MSCs) had a reduced capacity to support long-term hematopoiesis of HSPCs that completely recovered on blockade of TGFβ signaling. Furthermore, we found defective actin assembly and down-regulation of the adhesion receptor CD44 in MM HSPCs functionally reflected by impaired migration and adhesion. Still, transplantation into myeloma-free NOG mice revealed even enhanced engraftment and normal differentiation capacities of MM HSPCs, which underlines that functional impairment of HSPCs depends on MM-related microenvironmental cues and is reversible. Taken together, these data implicate that hematopoietic suppression in MM emerges from the HSPCs as a result of MM-related microenvironmental alterations.

Treatment with natalizumab, an antibody blocking the α4-integrin, is associated with increased numbers of circulating CD34+ cells in the peripheral blood of patients with multiple sclerosis.To determine whether natalizumab mobilizes CD34+ cells from or inhibits homing to the bone marrow (BM).Fifty-two patients with relapsing-remitting multiple sclerosis treated with natalizumab were included. Flow cytometric analyses; polymerase chain reaction assays for JC (John Cunningham) virus DNA detection; and adhesion, migration, and apoptosis assays of immunomagnetically enriched peripheral blood and BM CD34+ cells were conducted. A comparison was made with CD34+ cells from granulocyte colony-stimulating factor-mobilized peripheral blood or steady-state BM of age- and sex-matched healthy donors.We found adhesion and migration of peripheral blood-derived CD34+ cells to be reduced. In BM aspirates from natalizumab-treated patients, the cellularity, the proportion, and the adhesive capacity of CD34+ cells were normal. The JC virus was undetectable.Natalizumab mediates an increase in circulating CD34+ cells by interfering with homing to the BM. Thus, CD34+ cells appear unlikely to represent a source mobilizing JC virus out of the BM in patients treated with natalizumab.

Acute myeloid leukemia is a heterogeneous disease with varying genetic and molecular pathologies. Non-steroidal anti-inflammatory drugs (NSAIDs) have been proven to possess significant anti-proliferative potential in various cancer cells in vitro and in vivo. Hence, treatment with these agents can be utilized to study disease specific anti-proliferative pathways. In this study, a total number of 42 bone marrow derived CD34(+) selected de novo AML patient samples and the AML cell lines THP-1 and HL-60 were treated with the NSAIDs Sulindac sulfide and Diclofenac. We analyzed viability, apoptosis, differentiation and addressed the molecular mechanisms involved. We found a consistent induction of apoptosis and to some extent an increased myeloid differentiation capacity in NSAID treated AML cells. Comprehensive protein and gene expression profiling of Diclofenac treated AML cells revealed transcriptional activation of GADD45α and its downstream MAPK/JNK pathway as well as increased protein levels of the caspase-3 precursor. This pointed towards a role of the c-Jun NH(2)-terminal kinase (JNK) in NSAID mediated apoptosis that we found indeed to be dependent on JNK activity as addition of a specific JNK-inhibitor abrogated apoptosis. Furthermore, the AP-1 transcription factor family members' c-Jun, JunB and Fra-2 were transcriptionally activated in NSAID treated AML cells and re-expression of these transcription factors led to activation of GADD45α with induction of apoptosis. Mechanistically, we demonstrate that NSAIDs induce apoptosis in AML through a novel pathway involving increased expression of AP-1 heterodimers, which by itself is sufficient to induce GADD45α expression with consecutive activation of JNK and induction of apoptosis.

Since its introduction in 1983, high-dose therapy followed by autologous peripheral blood stem cell transplantation is a pillar of the treatment of patients with multiple myeloma. In the last decades, a multitude of clinical trials helped to improve strategies based on high-dose therapy and autologous stem cell transplantation resulting in a continuously prolongation of overall survival of patients. In this chapter we will review the progress, which has been made in order to enhance the mobilisation of autologous stem cells and increase the effectiveness of this treatment.

Acute myeloid leukemia (AML) is a heterogeneous hematological malignancy. Treatment of patients suffering from high-risk AML as defined by clinical parameters, cytogenetics, and/or molecular analyses is often unsuccessful. OSI-461 is a pro-apoptotic compound that has been proposed as a novel therapeutic option for patients suffering from solid tumors like prostate or colorectal carcinoma. But little is known about its anti-proliferative potential in AML. Hence, we treated bone marrow derived CD34(+) selected blast cells from 20 AML patients and the five AML cell lines KG-1a, THP-1, HL-60, U-937, and MV4-11 with the physiologically achievable concentration of 1 μM OSI-461 or equal amounts of DMSO as a control. Following incubation with OSI-461, we found a consistent induction of apoptosis and an accumulation of cells in the G2/M phase of the cell cycle. In addition, we demonstrate that the OSI-461 mediated anti-proliferative effects observed in AML are associated with the induction of the pro-apoptotic cytokine mda-7/IL-24 and activation of the growth arrest and DNA-damage inducible genes (GADD) 45α and 45γ. Furthermore, OSI-461 treated leukemia cells did not regain their proliferative potential for up to 8 days after cessation of treatment following the initial 48 h treatment period with 1 μM OSI-461. This indicates sufficient targeting of the leukemia-initiating cells in our in vitro experiments through OSI-461. The AML samples tested in this study included samples from patients who were resistant to conventional chemotherapy and/or had FLT3-ITD mutations demonstrating the high potential of OSI-461 in human AML.

Since its introduction in 1983, high-dose therapy followed by autologous peripheral blood stem cell transplantation is a pillar of the treatment of patients with multiple myeloma. In the last decades, a multitude of clinical trials helped to improve strategies based on high-dose therapy and autologous stem cell transplantation resulting in a continuously prolongation of overall survival of patients. In this chapter we will review the progress, which has been made in order to enhance the mobilisation of autologous stem cells and increase the effectiveness of this treatment.

In the current study, we evaluated a combination of tacrolimus and mycophenolate mofetil (MMF) as GvHD prophylaxis in 50 patients undergoing truly nonmyeloablative (NM; 90 mg/m(2) fludarabine, 2 Gy TBI) hematopoietic SCT (HSCT) from unrelated donors. Median patient age was 51 years (range, 25-67 years). After a median follow-up of 1123 days (range, 47-2729 days), 20 patients (40%) are alive and free from disease. The probabilities of 1-, 2- and 3-year survival were 57, 47 and 39%, respectively. Patients who achieved a remission before HSCT had a significantly better OS compared with those who had active disease (P=0.01). The incidences of grade II-IV and III-IV acute GvHD (aGvHD) were 54% (n=27) and 16% (n=8). Remarkably, using tacrolimus and MMF, the median onset of aGvHD occurred distinctly late on day +66 (range, 12-119 days). A total of 46 patients were evaluable for chronic GvHD (cGvHD). Out of these, 26 (56%) patients developed cGvHD, with 16 (34%) of them showing limited and 10 (21%) showing extensive disease. We conclude that the combination of tacrolimus and MMF as post transplant immunosuppression for patients receiving NM unrelated donor HSCT permits stable engraftment and effective prophylaxis for acute and cGvHD. In particular, the occurrence of severe early-onset aGvHD was attenuated.

We retrospectively determined whether a 3-day short course of palifermin could reduce the toxicity of high-dose therapy (HDT) and autologous blood stem-cell transplantation (ASCT) in patients with multiple myeloma (MM).Sixty-seven consecutive patients received 60 mug/kg palifermin for 3 days before HDT with melphalan 200 or 140 mg/m(2) for patients with renal failure (group A). Granulocyte colony-stimulating factor (G-CSF) was applied after ASCT. Data on haematopoietic reconstitution and toxicity were compared with two previously published patient groups from our institution who had received pegfilgrastim but not palifermin (group B, n = 21) and patients who had received neither palifermin nor G-CSF (group C, n = 21).In group A, patients with renal failure had a significantly higher risk for severe mucositis (64% versus 16%, P0.002). Patients with normal renal function who received palifermin experienced significantly less days of hospitalisation (P0.05) and less need for narcotic analgesia (P0.05), parenteral nutrition (P0.05) and erythrocyte transfusions (P0.05) in comparison with groups B and C. Time to haematopoietic reconstitution was not compromised by the use of palifermin.In conclusion, a short 3-day course of palifermin may be able to reduce the toxicity of HDT and ASCT in patients with MM. Patients with impaired renal function at the time of HDT need additional strategies to further reduce the incidence of severe mucositis.

Objective In patients with multiple myeloma, bendamustine monotherapy is effective as 1st and 2nd line therapy. However, data for patients with advanced multiple myeloma is rare. Methods In this retrospective analysis we have identified 39 patients with relapsed or refractory multiple myeloma by means of case research, who have been treated at our institution with bendamustine as salvage therapy. After in median 2 lines of prior therapy (range:1-5) patients received in median 3 (range: 1-10) cycles of bendamustine. Bendamustine dosage was 80-150 mg on day 1+2 of a monthly cycle. Bendamustine was administered as monotherapy in 39% of patients, whereas 61% received concomitant steroids. Results Toxicity was mild to moderate. Response rates were as follows: 3% vgPR, 33% PR, 18% MR, 26% SD and 20% PD. The median event-free and overall survival were 7 and 17 months, respectively. Conclusions In conclusion, in patients with advanced multiple myeloma bendamustine is effective and associated with mild toxicity. Therefore, the role of bendamustine in patients with multiple myeloma should be investigated in further clinical trials.

In this study we investigated paracrine factors like HGF, insulin like growth factor 1 (IGF-1) stroma derived factor 1 (SDF-1) and stem cell factor (SCF) for correlation with peripheral progenitor mobilisation in the early course of hepatic resection using FACS-analyses in 30 patients and the extend of partial hepatectomy. CT-scan volumetry pre-operatively and 24 h following resection was utilized to determine the exact extend of liver volume loss. Serum growth fators and chemokine levels were compared among 20 patients with resection volume of less than 20 % (group A) of the pre-operative total liver volume – tumor volume (TLV) and 10 patients with a resection extend of 30 to 65 % (group B). In addition, peripheral CD133+ and CD34+ progenitor cells in peripheral blood were contrasted between the two groups up to post OP day (POD) 21. Early subsequent to the end of resection HGF (0, 6 and 24 h), SDF-1 (0, 3 and 6 h) and IGF-1 (3 h) were significantly increased in comparison to group A. We revealed a significant elevation from day 2 following liver surgery for CD133+ cells which was only seen for group B individuals and which was significantly superior to group A patients (p = 0.005). CD34+ cells demonstrated similar kinetics and differences among groups, however to a lesser extend. Only HGF directly correlated with mobilised mobilised CD34+ and CD133+ peripheral cells early after resection, independent of the extend of hepatectomy. These data suggest HGF to play a role in mobilisation of CD133+ and CD34+ cells respectively in regeneration processes subsequent to larger extend of loss of hepatic tissue.

Patients with AML or myelodysplastic syndrome who relapse after allo-SCT have a poor prognosis. In the search for novel treatment strategies for these patients, we conducted a multicenter retrospective analysis and identified 22 patients treated with the DNA-methylation inhibitor 5-azacytidine (5-Aza). Patients received a median number of two cycles 5-Aza (range 1-8) at a dose of 100 mg/m(2) over 5 days following relapse. Eighteen patients (82%) also received a median number of two donor lymphocyte infusions (DLI, range 1-5). Sixteen patients (72%) responded to 5-Aza treatment and five patients (23%) achieved a CR. 5-Aza-induced CR lasted for 433 days (median, range 114-769). Median survival and the estimated 2-year survival rate were 144 days and 23%, respectively. Acute GVHD after DLI was seen in six patients (33%) and four of these patients developed chronic GVHD of the skin. There were no treatment-related deaths. Patients who achieved halving of leukocyte counts after the first 5-Aza cycle had a superior median survival of 802 days compared with 135 days (P=0.0025) in all other patients. On univariate analysis, the achievement of this halving of leukocyte counts was identified as a significant predictor of survival.

Thrombocytopenia is a frequent symptom and clinical challenge in patients with myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Eltrombopag is a small molecule thrombopoietin receptor agonist that might be a new option to treat thrombocytopenia in these diseases, provided that it does not stimulate malignant hematopoiesis. In this work, we studied the effects of Eltrombopag on proliferation, apoptosis, differentiation, colony formation, and malignant self-renewal of bone marrow mononuclear cells of patients with AML and MDS. Malignant bone marrow mononuclear cells did not show increased proliferation, or increased clonogenic capacity at concentrations of Eltrombopag ranging from 0.1 to 30 μg/mL. On the contrary, we observed a moderate, statistically nonsignificant (P = .18), decrease of numbers of malignant cells (mean, 56%; SD, 28%). Eltrombopag neither led to increased 5-bromo-2-deoxyuridine incorporation, decreased apoptosis, an increase of malignant self-renewal, nor enhanced in vivo engraftment in xenotransplantations. Furthermore, we found that Eltrombopag was capable of increasing megakaryocytic differentiation and formation of normal megakaryocytic colonies in patients with AML and MDS. These results provide a preclinical rationale for further testing of Eltrombopag for treatment of thrombocytopenia in AML and MDS.