Plt Response Research Articles

Efficacy and Safety of Danazol in Patients with Myelodysplastic Syndromes or Myelodysplastic/Myeloproliferative Neoplasms: A Multicenter Observational Study

Thrombocytopenia affects about two thirds of patients with myelodysplastic syndromes (MDS) and treatment is not standardized. Immunosuppressants, such as corticosteroids, cyclosporin or anti-thymocyte globulin show some efficacy, particularly in hypocellular cases, and eltrombopag was associated with a 47% PLT response. The androgen danazol may be beneficial in this setting given its anabolizing and immunomodulatory properties. In this observational multicenter study, 59 patients with MDS (53) or MDS/myeloproliferative neoplasms (MDS/MPN; 5 chronic myelomonocytic leukemia, CMML, 1 unclassified) treated with off-label danazol at 6 centers in Northern Italy were retrospectively evaluated. Response was assessed at 3-month intervals according to IWG 2018 criteria. Adverse events were registered according to CTCAE version 5. A two-tailed Fisher's exact test was used to calculate p values for differences in dichotomous variables, whereas Student's t test was used for continuous variables. Log Rank Mantel-Cox test was used for survival analysis. As shown in Table 1, patients were mainly males with a median age of 69 years (27-87), and were equally distributed between very low/low IPSS-R risk score (47%), and intermediate/higher risk (53%). Twenty percent (9/44 evaluable) of patients had a hypocellular bone marrow (<25% cellularity), and 26% (11/42) had WHO grade 2 fibrosis. All patients were thrombocytopenic (median 21 x 103/μL, range 2 - 98), 52% were anemic (median Hb 11.1 g/dL, 6.9 - 15.7), and 25% had received at least 1 red blood cell transfusion in the 8 weeks before danazol initiation. Danazol was administered for a median of 11.3 months (0.6 - 149.5) at a meandaily dose of 450 mg (range 125 - 600). Concomitant treatments were corticosteroids (34%), recombinant erythropoietin (rEPO 7%), and corticosteroids plus rEPO (3%). PLT response was obtained in 54% of evaluable patients (30/56) after a median of 3.3 months (1.3 - 24.6) from treatment start. Response was slightly higher in patients with greater baseline PLT levels (mean baseline PLT count 25 vs 19 x 103/mcL for responders vs non-responders, respectively, p 0.07), grade 0-1 fibrosis (64% response vs 27% in those with grade 2, p 0.07) and concomitant use of steroids (77% vs 45% response, p 0.06). Erythroid improvement was obtained in 7/16 (44%) patients after a median of 6.8 months (2.5 - 16.8), independently from concomitant rEPO or steroid administration. After a median of 17.2 months from initial PLT response, 78% of patients maintained it, whereas 22% relapsed. AEs occurred in 68% of cases, mainly grade 1-2, including creatinine increase (44%; 5% grade 3), transaminitis (36%), mood disorders (7%), and others. AEs required dose reduction in 11 (19%) and interruption in 4 (7%) of patients. Twenty-eight patients died during the follow up. PLT-responders had a significantly lower mortality rate compared to non-responders (10/27, 37%, vs 16/23, 70; p = 0.02) and a longer overall survival (p < 0.001, figure 1). In colcusion, danazol induced PLT response in more than half of MDS patients and erythroid improvement in 44%, including non-responders to steroids and cyclosporin, and independently of marrow cellularity. PLT response was significantly associated with a higher overall survival further suggesting a clinical impact on patient outcome. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Platelet Phosphatidylserine Is the Critical Mediator of Increased Thrombus Formation in Heparin-Induced Thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is a severe adverse event that is caused by the interaction of platelets with ultra-large platelet factor 4 (PF4)/heparin IgG-immune complexes. Previous studies have shown that HIT Abs harbour the potential to interact with PLT Fc-gamma-RIIA leading to PLT activation and interplay with different actors of the innate and adaptive immune system. Despite this mechanistic insights, the role of different HIT Ab-induced PLT subpopulations that might contribute to an increased pro-thrombotic potential and severe patient outcome, remains poorly understood. In this study, we hypothesized that PF4/heparin HIT Abs induce a procoagulant PLT response that contribute to an increased pro-thrombotic environment. Using flow cytometry, we found that HIT patient Abs have the capability to induce a procoagulant (P-Selectin/phosphatidylserine double positive) PLT phenotype (p=0.0039) with increased thrombin generation potential (p<0.0001). Most importantly, the perfusion of whole blood samples that were spiked with HIT Ab-induced procoagulant PLTs resulted in significant increase of procoagulant (Annexin-V positive) PLT and fibrin deposition. Interestingly, Fc-gamma-RIIA inhibition via monoclonal antibody IV.3 resulted in a nearly complete abrogation of HIT Ab-induced thrombus formation, indicating that PLT Fc-gamma-RIIA signalling mechanisms are pivotal for Ab-induced pro-thrombotic PLT potential (p=0.0108, Figure 1A). Moreover, also the prostacyclin analogue Iloprost prevented procoagulant PLTs and increased thrombus formation despite the presence of HIT Abs and low dose (0.2 IUs/mL) heparin (p=0.0029). A finding that might be most probably due to increased intracellular concentrations of the second messenger cAMP due to increased PKA activity. To deeper investigate how increased CD62p expression and high PS externalization on the procoagulant PLT surface contribute to the prothrombotic potential of HIT Ab-induced procoagulant PLTs, we performed specific inhibition experiments. Although a marked reduction of neutrophil granulocyte deposition was observed, blocking of PLT CD62p did not reduced HIT Ab-induced increased thrombin generation or thrombus formation. In contrast, procoagulant PLTs that were treated with lactadherin, a PS binding and blocking protein resulted in a significant reduction of thrombin generation (p=0.0040) and thrombus formation compared to the vehicle control (p=0.0005, Figure 1B). Findings of our study indicate that HIT patient Abs harbour the ability to induce procoagulant PLTs via PLT FcγRIIA mediated signalling pathways. The observation that Iloprost reduced the formation of procoagulant PLTs and most importantly inhibits thrombus formation indicates a potential therapeutic use. Most importantly, based on our mechanistic studies we conclude that increased PS on the surface of procoagulant PLTs might be the causing factor for increased pro-thrombotic potential observed in HIT. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Phase I Dose-Finding Study of Eltrombopag Following High Dose Cytarabine and Mitoxantrone Chemotherapy in Patients with Relapsed/Refractory Acute Myeloid Leukemia

Phase I Dose-Finding Study of Eltrombopag Following High Dose Cytarabine and Mitoxantrone Chemotherapy in Patients with Relapsed/Refractory Acute Myeloid Leukemia

Long-Term Maintenance of Platelet Responses in Adult Patients with Persistent/Chronic Immune Thrombocytopenia Treated with Fostamatinib: 1-Year Efficacy and Safety Results

Long-Term Maintenance of Platelet Responses in Adult Patients with Persistent/Chronic Immune Thrombocytopenia Treated with Fostamatinib: 1-Year Efficacy and Safety Results

Long-Term Response Rates in Patients with Chronic Immune Thrombocytopenia Treated with Avatrombopag: Additional Analyses from a Phase 3 Study and Its Extension Phase

Background: Avatrombopag (AVA) is a novel, oral thrombopoietin receptor agonist (TPO-RA) recently FDA approved for the treatment of chronic immune thrombocytopenia (ITP) in patients not responding to prior therapies. Additionally, AVA is approved for the treatment of thrombocytopenia in chronic liver disease patients undergoing a procedure. Unlike eltrombopag, AVA absorption is not affected by dietary fat or polyvalent cations (e.g., calcium, magnesium, iron, etc.) facilitating ease of use by patients and it also has not been associated with hepatotoxicity. A randomized, controlled, double-blind phase 3 study including 32 ITP patients treated with AVA and 17 treated with placebo (PBO) for 6 months was previously published (Jurczak et al., 2018), demonstrating the superiority of AVA to PBO in median cumulative weeks achieving platelet counts (Plt) ≥50,000/µL (12.4 vs. 0.0 weeks, p&lt;0.0001), and a rapid onset of action (65.6% achieved Plt ≥ 50,000/µL on Day 8 for AVA vs. 0% for placebo (p&lt;0.0001). In addition, AVA had a favorable safety profile with headache, fatigue, petechiae, contusion, and upper respiratory tract infection reported as the most common adverse events. Long-term AVA response rates in ITP have not previously been published. Methods and Aims: After the phase 3 core study, patients had the option to continue on to receive AVA in an open-label extension phase. Patients were eligible for the extension phase if they had completed the 6-month core study or discontinued treatment due to lack of efficacy in the core study. We analyzed the response rates for patients utilizing two classes of response: 1) a Plt response was defined as Plt ≥50,000/µL as measured during an on-study patient visit, and 2) a complete Plt response was defined as Plt ≥100,000/µL as measured during an on-study patient visit. A subset of "durable responders" who achieved a Plt response for 6 of the final 8 weeks of the core study (34.4% of AVA patients qualified as durable responders), was also analyzed separately to assess for maintenance of this high response rate in the extension phase. Results: The mean duration of study participation was 23 weeks in the core study and 44 (range, 8-76) weeks overall (core plus extension) including 21 and 19 scheduled visits per patient in core and extension, respectively, for patients completing both studies. In the core study, a Plt response (Plt ≥50,000/µL) was achieved at 48.6% of patient visits for AVA, compared with &lt;0.01% for PBO. In the open-label extension phase for those patients continuing AVA treatment, a Plt response was achieved at 44.2% of visits. For PBO patients who rolled over to AVA in the extension phase, a Plt response was achieved at 41.4% of visits. For all patients ever exposed to AVA (core phase AVA arm and PBO patients rolled over to AVA) during the core study and extension phase, 46.4% of visits achieved a Plt response. In durable responders from the core study (as defined above), a Plt response was achieved at 96.1% of the extension phase visits. During the core study, a complete Plt response (Plt ≥100,000/µL) was achieved at 25.6% of visits in AVA-treated patients versus &lt;0.01% in the PBO treatment group. During the open label extension phase for patients treated with AVA, a complete Plt response was achieved at 24.2% of visits. For the PBO-treated patients in the core study who rolled over to AVA in the extension phase, a complete response was achieved in 18.3% of the extension phase visits. In total for all patients ever treated with AVA (core phase AVA arm and PBO patients rolled over to AVA), a complete Plt response was achieved at 23.5% of AVA study visits throughout the core study and extension phase. In durable responders from the core study, a complete Plt response was achieved at 60.0% of the extension phase visits. Response rates for AVA-treated patients are summarized in the table below. Conclusions: Plt response rates were similar in the core study and extension phase. Durable responders maintained a high rate of Plt response and complete Plt response in the extension phase, providing evidence that AVA-responding patients will continue to respond for extended treatment periods. Additionally, consistent efficacy was noted, as patients in the PBO group who rolled over to active drug demonstrated similar efficacy as AVA-treated patients. AVA-treated patients had substantially higher Plt response and complete Plt response rates than those treated with PBO. Figure Disclosures Al-Samkari: Dova: Consultancy, Research Funding; Moderna: Consultancy; Agios: Consultancy, Research Funding. Aggarwal:Dova Pharmaceuticals: Employment. Vredenburg:Dova Pharmaceuticals: Employment, Other: Shareholder. Allen:Dova Pharmaceuticals: Equity Ownership, Other: Chief Medical Officer .

Upfront azacitidine (AZA) in juvenile myelomonocytic leukemia (JMML): Interim analysis of the prospective AZA-JMML-001 study.

10031 Background: Hematopoietic stem cell transplantation (HSCT) is the only curative therapy for JMML patients (pts). Novel therapies controlling the disorder prior to HSCT are urgently needed. A phase 2, multicenter, open-label study was conducted to evaluate safety and anti-leukemia activity of AZA monotherapy prior to HSCT in pts with newly diagnosed (ND) JMML. Methods: AZA (75 mg/m2 IV) was administered once daily on days 1–7 of each 28-day cycle (C). Primary endpoint was number of pts with clinical complete remission or clinical partial remission (cPR) at C3 day (D) 28 (C3D28). Results: 18 JMML pts (13 PTPN11-, 3 NRAS-, 1 KRAS-, 1 NF1-mutated) were enrolled from 09/2015 to 11/2017. Median (range) white blood cell and platelet (Plt) counts were 19.7 (4.3–59.0) × 109/L and 28 (7–85) × 109/L, respectively. DNA methylation class (MC) was high, intermediate (int), or low in 11, 5, and 2 pts, respectively. 16 pts completed C3 and 5 pts C6. 2 pts discontinued treatment (Tx) pre-C3D28 due to disease progression (PD). 6 pts (33%) had ≥ 1 grade (Gr) 3–4 manageable adverse event (AE) related to AZA. Most common Gr 3–4 AEs related to AZA were neutropenia (2) and anemia (2). 11 pts (61%) were in cPR at C3D28; 7 had PD at C3D28 or prior. All 7 pts of the int/low MC and 4/11 in high MC achieved cPR. 17 pts received HSCT at median of 58 days (37–518) from last AZA dose; 14 were leukemia-free at a median follow-up of 15.7 months (0.1–31.7) after HSCT. 2 pts (high MC) given HSCT relapsed after allograft. 16/18 pts were alive at a median follow-up of 19.8 months (2.6–37.3) from diagnosis. 1 pt discontinuing Tx prior to C3 died from PD; 1 non-responder died from transplant-related causes. Plt response in pts with cPR prompted retrospective comparison of Plt counts at time of HSCT with a historical registry control cohort. Pts with NF1-mutated JMML with higher Plt counts versus other genetic subtypes were excluded. While 7/16 (44%) study pts had Plt counts ≥ 100 × 109/L at HSCT, only 10/58 (17%) historical cohort pts reached this cutoff ( P &lt; 0.01). Conclusions: This study shows that AZA monotherapy was well tolerated in pts with ND JMML. Although the long-term advantage of AZA Tx remains to be fully assessed, responses show it was effective in JMML and provided clinical benefit to pts in this study. Clinical trial information: NCT02447666.

Newly Diagnosed Pernicious Anemia Can be Treated with a Single Megadose of Cobalamin. Results of a Pilot Trial

Introduction: Pernicious anemia is the leading cause of vitamin B12 deficiency worldwide, caused by an autoimmune reaction against parietal cells in the gastric mucosa leading to B12 absorption impairment. The treatment of pernicious anemia is based on replacement of cobalamin, oral and sublingual routes have been described nevertheless its absorption is erratic. The recommended schedules for vitamin B12 replacement is an intramuscular injection of 1000μg every other day for 1 to 2 weeks followed by weekly injections for a month and then tapered to once a month indefinitely (Green.Blood 2017;129(19):2603-2611). Such an approach can limit treatment adherence for patients in a resource-poor setting and may be unnecessary. Furthermore, the toxicity of cobalamin is minimal, while the benefit of larger doses is unknown.Objective: We aim to demonstrate that a single mega-dose intramuscular (IM) injection of a multivitamin formulation is sufficient to achieve and maintain a complete hematologic response for a six-month period.Methods: We performed a single center pilot study approved by our ethics committee and registered in Clinicaltrials.gov (NCT03372447). All patients with newly diagnosed, untreated pernicious anemia ≥18 years were included after written informed consent was obtained. A single IM dose of a multivitamin formulation consisting on cobalamin 10,000 μg, thiamin 100 mg, and pyridoxine 50 mg was administered. Complete blood count (CBC) was performed at 15 and 30 days and monthly thereafter for a total of six months. Partial response (PR) was considered when Hb ≥10g/dl, Normal WBC, PLT ≥100x103/μL, Complete response (CR) was defined as Hb ≥12g/dl, normal WBC and PLT. Our primary outcome was normalization of CBC (CR) at 6 months. As secondary outcomes we evaluated safety and measured levels of methylmalonic acid (MMA), homocysteine (HCY) and B12 levels (B12L) at diagnosis, three and six months after treatment.Results: Eight patients have been enrolled (5 men and 3 women), median age was 58 years (range 25-77). None had neurological symptoms at presentation. Median laboratory values at diagnosis were Hb 5.9 g/dL (range 3.9-10.7), mean corpuscular volume 113.2 fL (range 94.6-122.9), WBC 2.68x103/μL (range 1.26-6.08), PLT 93x103/μL (range 9.75-156,000), lactic dehydrogenase 3082IU/L (range 439-9840), B12L 85 pg/ml (range 83-90), HCY 154.09 μmol/L (range 83.7-182.44), MMA 24435 nmol/L (range 5175-99500). By day 30 all patients achieved PR. At the end of the third month, 100% of patients reached a CR regarding Hb and WBC while 88% of patients reached a complete PLT response. Median Hb increment at 1 month and 3 months was 6.15g/dl (range 3.1-7.74) and 1.8g/dl (range 0.4-3.7) respectively. The difference between Hb concentration at all time-points was statistically significant (ANOVA; p=0.002) particularly in the first 15 days (p=0.025), while post hoc testing revealed that increments in Hb after the second-week post-treatment were not (p>0.05). Until now, 4/8 patients have completed the primary outcome and all of them have maintained CR and normal levels of HCY and B12L without further cobalamin doses, only one patient had an asymptomatic increase of MMA. No adverse events following the administration of multivitamin preparation were documented.Conclusions: A single dose of a 10,000μg B12 multivitamin was safe and tolerated. Thus far all patients have achieved and maintained a response for at least six months. This simplified single cobalamin administration is an effective option for the treatment of pernicious anemia. [Display omitted] DisclosuresGomez-Almaguer:AbbVie: Consultancy; Novartis: Consultancy.

A Single-Arm, Open-Label, Long-Term Efficacy and Safety Study of Subcutaneous (SC) Romiplostim in Children with Immune Thrombocytopenia (ITP)

A Single-Arm, Open-Label, Long-Term Efficacy and Safety Study of Subcutaneous (SC) Romiplostim in Children with Immune Thrombocytopenia (ITP)

Romiplostim in Patients Undergoing Allogeneic Stem Cell Transplantation: Results of a Phase I/II Multicenter Trial

Background: Delayed platelet (plt) recovery and secondary thrombocytopenia occur in 5-25% of patients (pts) after hematopoietic stem cell transplantation (HSCT) and is of adverse prognostic significance. Plt transfusion to prevent bleeding remains a mainstay of therapy and role of thrombopoietic agents is not known. In this phase I/II multicenter open trial, we investigated the safety and efficacy of romiplostim (Nplate; Amgen, thousand Oaks, CA) for (pts) with transfusion-dependent thrombocytopenia after allogeneic HSCT (NCT01980030).Patients and methods: Adult pts undergoing standard of care allogeneic HSCT for any disease except myelodysplastic syndrome were eligible for this study 45 days or more after transplantation if they had plt count ² 20 x 109/L sustained for 7 days (² 50 x 109/L with a history of bleeding) or if they were plt transfusion dependent. Pts were excluded if they had abnormal liver function tests, serum creatinine ³ 176.8 μmol/L or had prior venous thrombosis. Pts were given weekly romiplostim for 12 weeks with intra-pt weekly dose escalation from 1µg/Kg to a maximum dose of 10 µg/Kg (with a dose reduction schema in case of plt overshoot). The study was composed of a 12-week treatment period. The primarysafety endpoint was the incidence of any grade 3 or 4 adverse events after HSCT, excluding those expected from the HSCT, as well as clinically significant bleeding events. The primary efficacy endpoint was time to reach a plt count above 50 x 109/L free of plt transfusion. Secondary endpoints were the durable plt response defined as a plt count above 50 x 109/L during 8 consecutive weeks independent of plts transfusions, the 1-year cumulative incidence (CumI) after HSCT of Graft versus host disease (GvHD), relapse and non-relapse mortality rates. All pts had a bone marrow biopsy before treatment and at one year. This study was approved by the research review board of the Hospital Saint-Louis (Paris, France). Statistical analysis was based on a modified intent-to-treat basis, excluding pts who did not fulfill the inclusion criteria. CumI were estimated using nonparametric methods, where deaths prior to the event of interest defined competing risks.Results: 25 pts were included in 4 different HSCT French units between April 2013 and November 2015. The analysis was restricted to 24 pts (one pt with plt count > 20x109/L after inclusion). All but one pt have malignant disease (13/24 acute leukemia). Donor type was related for 12 pts. Stem cell source was peripheral blood in 15 pts and bone marrow in 9 pts, myeloablative conditioning regimen was used in 17 pts. Median time between HSCT and romiplostim initiation was 85 days (interquartile range, IQR 63 - 117). Nineteen pts completed the 12 investigational injections of romiplostim, while five did not due to 3 deaths (1 post transplantation EBV-related lymphoproliferative disorder, 1 relapse and 1 septic shock), 1 boost of donor stem cells and one pt with plt count above 50 Giga/L after 8 injections. A total of 21 adverse events (grade 3, n=10; grade 4 n=11) considered possibly related to romiplostim were reported in 6 pts. Hematological complications appeared in 4 pts (2 neutropenia, 1 anemia and 1 pancytopenia) and liver dysfunction was present in 2 pts (mild cytolysis). Overall, romiplostim was well tolerated with a 6 months adverse events CI of 25.2% (95%IC 7.3 - 43.2). No bleeding event as well as no thrombotic complications appeared. None of the pts developed fibrosis 1 year post treatment (2 pts not yet at 1 year). After romiplostim initiation, 20 pts received a plt transfusion. The median time to reach a plt count above 50 x 109/L free of plt transfusion was 36 days (Figure 1), with required doses of 4 mg/Kg (IQR, 3-6). Fifteen pts obtained a durable plt response. A total of 17 and 12 pts experienced aGVHD and cGVHD, respectively, with 100 days CumI of aGVHD of 67% (95%CI, 47-87) and 1-year CumI of cGvHD of 55% (95%CI, 32-78), respectively. Six pts died during the study (1 PTLD, 1 relapse, 1 septic shock, 1 lung aspergillosis and 2 acute distress respiratory syndrome of unknown origin). CumI of non-relapse mortality was thus of 21% (95%CI, 7-42%).Conclusion: Romiplostim can be safely administered and improves plt count in pts with thrombocytopenia after allogeneic HSCT. The required dose to reach plt count above 50 x 109/L is 4 mg/Kg with a median time of 36 days.Research support was provided in part by Amgen. [Display omitted] DisclosuresPeffault de Latour:Alexion: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Amgen: Research Funding.

Thrombopoietin Receptor Agonist (TPO-RA) Switch in Adult Primary Immune Thrombocytopenia (ITP) Patients: A Retrospective Collaborative Survey from 8 Italian Hematology Centers

▪Introduction. Availability of the 2 TPO-RAs Romiplostim (Rom) and Eltrombopag (El) offers an effective treatment option for primary ITP patients (pts). However, some pts are either not responsive or lose response - i.e. desired platelet (plt) count achieved but not sustained over time, or experience wide fluctuations in plt count with either TPO-RA. Adverse events may cause treatment discontinuation. Finally, ptÕs preference may be an important issue considering the different route and timing of administration of the two agents. Availability of two TPO-RAs for clinical use, with different molecular structure and site of binding within the TPO receptor, makes it appealing to try switching with the aim of overcoming treatment limitations of either agent. The present survey offers insight into outcome of TPO-RA switching in a group of ITP pts treated at 8 Centers representative of the Italian territory.Patients. Charts of ITP pts on treatment who underwent TPO-RA switch were retrospectively reviewed.Results. Between Jan 2009 and Feb 2015, 57 of 249 pts on TPO-RA (22,9%) underwent switch: El ˆ Rom 26/57 (45.6%), Rom ˆEl 31/57 (54.4%). Median age at 1st TPO-RA administration was 55 yrs (range 16-81); M/F = 23/34. Median disease duration prior to 1st TPO: 58 mos (range 2-648). Median lines of previous therapy 3 (range 1-6; splenectomy: 23/57, 40.4%). Overall 42/57 pts (73,7%) had received maximum product dose as per prescribing information prior to switch. Table 1 summarizes reasons for TPO-RA switch and outcome. Overall, 32/57 pts (56.1%) achieved, regained or maintained a response upon switching. The majority of pts (39/57, 68.5%) were switched for efficacy issues, i.e. failure to respond to 1st TPO (27 pts) or response loss (12 pts); among these 39 pts, 48.7% responded to the 2nd TPO-RA. One pt lost response to Rom because of development of neutralizing antibodies; response was regained upon switching to El.In this subgroup of pts, disease duration and lines of previous therapy (but not splenectomy status) seem to have an impact on response to switching. Each one month increase in disease duration determines a 0.7% decrease in the odds of achieving a response (WaldÕs test p=0.065). More than 2 lines of therapy determine a 72% decrease in the odds of achieving a response (WaldÕs test p=0.077). Either TPO-RA switch sequence was equally effective in yielding response (FisherÕs exact test p=0.752) and age at 1st TPO-RA had no impact on response. Of the 18 pts switched for reasons other than efficacy, 13 (72.2%) maintained a response on the 2nd TPO-RA: 5/6 switched for plt count instability (counts stabilized = 2/5 responding pts), 4/7 switched for ptÕs preference, 4/5 switched for side effects. Four pts (1 plt count instability, 3 ptÕs preference) underwent Òdouble switchÓ (i.e. Rom ˆ El ˆ Rom): re-exposure to Rom was not associated with response loss.Discussion. Switching enables approximately 56% of pts to achieve, regain or maintain a plt response; switching for inefficacy yields lower response rates (48.7%) compared to switching for reasons other than efficacy (72.2%) Plt counts fluctuation stabilized in 40% of pts. Re-exposure to R in the 4 pts who underwent Òdouble switchÓ was not associated with response loss, confirming absence of tachyphylaxis with this TPO-RA. Our results are in line with those reported by Khellaf (Haematologica 2013) and Gonzales-Porras (BJH 2014): TPO-RA switch can be a safe and appealing treatment option for ITP pts who experience suboptimal results with either agent.Table 1REASON for SWITCHINGn (%)NR (%)R (%)CR (%)All57 (100)25 (43.9)14 (24.6)18 (31.5)El->Rom26 (45.6)10 (38)8 (31)8 (31)Rom->El31 (54.4)10 (48.4)6 (19.4)10 (32.3)1st TPO-RA failure27 (47.4)16 (59)4 (15)7 (26)El->Rom157 (47)3 (20)5* (33)Rom->El129 (75)1 (8)2 (17)Loss of response12 (21.1)4 (33)2 (17)6 (50)El->Rom42 (50)1 (25)1 (25)Rom->El82 (25)1 (12.5)5 (62.5)Plt count fluctuation6 (10.5)1 (17)3 (50)2 (33)El->Rom2011Rom->El4121PtÕs preference7 (12.3)3 (42.9)2 (28.6)2 (28.6)El->Rom0000Rom->El7322Adverse event¡¡5 (8.8)1 (20.0)3 (60.0)1 (20.0)El->Rom5131Rom->El0000CR: complete response; R: response; NR: no response (Rodeghiero et al, Blood 2009)*1 NR secondary to neutralizing antibodies development¡¡1 hepatic enzyme increase, 1 CPK increase; 2 skin rash; 1 retinal thrombosis. DisclosuresDe Stefano:Janssen Cilag: Research Funding; Shire: Speakers Bureau; Amgen: Speakers Bureau; Bruno Farmaceutici: Research Funding; Novartis: Research Funding, Speakers Bureau; Roche: Research Funding; Celgene: Speakers Bureau; GlaxoSmithKline: Speakers Bureau.

A Final Analysis of a Phase 2, Single-Arm Study of Platelet (Plt) Responses and Remission Rates in Patients with Immune Thrombocytopenia (ITP) Receiving Romiplostim

A Final Analysis of a Phase 2, Single-Arm Study of Platelet (Plt) Responses and Remission Rates in Patients with Immune Thrombocytopenia (ITP) Receiving Romiplostim

A semi-physiologic population pharmacokinetic/pharmacodynamic (PK/PD) model of thrombocytopenia (TCP) characterizing the effect of trastuzumab-DM1 (T-DM1) on platelet counts in patients with HER2-positive MBC.

605 Background: T-DM1 is an antibody-drug conjugate in development for HER2-positive MBC. In clinical trials of single-agent T-DM1 for heavily pretreated patients (pts), TCP was the dose-limiting toxicity. TCP was generally transient, reversible and not associated with serious hemorrhage, with nadirs by day 8 post-treatment. In some pts, platelet (plt) time profiles drifted slowly down after multiple cycles of T-DM1, though development of grade ≥3 TCP was infrequent. Methods: A semi-physiologic population PK/PD model with transit compartments mimicking plt development and circulation was fit to the concentration-plt-time data from the phase I dose escalation study (TDM3569g; N=52) and a phase II study of single-agent T-DM1 (3.6 mg/kg q3w; TDM4258g; N=112). The rate and extent of plt drift was modeled as a time effect on the proliferation pool. NONMEM software was used for the modeling analyses, with a mixture model approach used to identify pt plt drifts. A separate phase II study (3.6 mg/kg; TDM4374g; N=110) was used for model validation. Results: The PK/PD model described the data well and predicted the 9% incidence of grade ≥3 TCP observed in the validation dataset (TDM4374g). The model also predicts that downward drifting plt profiles will eventually stabilize. In the model dataset, plt profiles from 25% of pts drifted downward much more rapidly than the rest of pts; these stabilized by 8 treatment cycles to typically 50% of the original baseline plt count. In 4374g, the overall plt response pattern was similar, with a subset of pts’ plt profiles drifting then stabilizing by 8 treatment cycles. Pt baseline characteristics were not significantly correlated with plt kinetics. Conclusions: The model accurately reflects clinical observations of plt counts during T-DM1 treatment and supports T-DM1 3.6 mg/kg q3w as a well-tolerated dose, requiring minimal delays/reductions for TCP. In addition, the model supports partial depletion of the plt proliferation pool as a mechanism for the downward drift in plt count. Plt response to T-DM1 could not be predicted a priori from baseline characteristics.

Subcutaneous or intravenous administration of romiplostim in thrombocytopenic patients with myelodysplastic syndrome (MDS)

7009 Background: Thrombocytopenia is common in patients (pts) with MDS, and treatment options are currently limited to platelet (plt) transfusions. Romiplostim is an Fc-peptide fusion protein (peptibody) that stimulates plt production by the same mechanism as thrombopoietin. Methods: This was a phase II, multicenter, single arm, open-label study. Eligibility criteria included IPSS low or intermediate-1 risk MDS and a mean baseline plt count ≤50x109/L. Safety and efficacy of romiplostim were evaluated in pts receiving 750μg romiplostim according to one of 3 schedules: weekly or biweekly subcutaneous injections (QWSC or Q2WSC), or biweekly intravenous injections (Q2WIV). Plt responses were measured per IWG 2006 criteria. Results: Of the 28 pts enrolled, 17 (61%) completed the study; 22 (79%) were male and the mean (±SD) baseline plt count was 29 (±10) x 109/L. The mean age was 71 years and 19 pts (68%) had received plt transfusions in the past year. Mean duration of exposure to romiplostim was 12 (±8) weeks. The most common adverse events (AEs) were fatigue and headache (both 18%). Five pts experienced serious AEs, and there were 2 cases of disease progression to AML: one pt in the QWSC cohort who received romiplostim for 4 weeks and one in the Q2WSC cohort who received romiplostim for 20 weeks. For pts who completed 8 weeks treatment, 15/23 (65%) achieved a plt response, defined by IWG 2006 criteria, and 14/23 (61%) did not require a plt transfusion during this period. The small number of pts limited the ability to compare administration schedules; minor differences were observed in plt responses and plt transfusions, and the incidence of AEs appeared similar among cohorts. Conclusions: IV and SC romiplostim appeared well-tolerated and effective in raising plt counts and avoiding plt transfusions in low and intermediate-1 risk MDS pts. The dose recommendation for future studies is 750μg, given QW or Q2W SC. [Table: see text] [Table: see text]

Treatment of Anemia in Myelodysplastic Syndrome (MDS) with Darbepoetin-Alpha (DPO) and Granulocyte Colony Stimulating Factor (G-CSF).

MDS is a clonal stem cell disorder characterized by ineffective hematopoiesis and peripheral cytopenias. Anemia is often severe, transfusion dependent and associated with impaired quality of life. Evidence shows that treatment with erythropoietin (EPO) has an overall response rate of 20% and with G-CSF becomes more effective with an erythroid response rate of around 40%. Studies have independently demonstrated a synergistic effect between EPO and G-CSF on the anemia of MDS. DPO, a modified form of EPO with a longer half life has been shown to be effective in correcting anemia in a significant proportion of MDS patients. Synergy between DPO and G-CSF has not been studied. We report the clinical course and changes in the blood counts in a 77 year old male diagnosed with MDS, Refractory Anemia with Excess Blasts Type I (RAEB-I) who received DPO and G-CSF combination treatment. His baseline CBC showed WBC-2.4 ×103/μL, Hb-9.7g/dL, and Plt-106×103/μL. EPO level was 64.4 mU/mL. He was initiated on EPO 20,000 units weekly (QW) which was titrated to 40,000 units QW after one month. His Hb increased to 12 g/dl. For convenience, he was switched from QW EPO injections to DPO 100 μg every two weeks (QOW). This was followed by an initial drop in the Hb to 11g/dL requiring an increase in DPO dose to 200 μg QOW which was followed by stabilization and maintenance of Hb between 10–11 g/dL. After 7 months, Hb dropped to 9 g/dL requiring an increase in DPO to 300 μg QOW. Hb increased to 10 g/dl and remained between 10–10.5 g/dL for 7 months. Hb dropped again to 8.3g/dL. The DPO dose was increased to 300 μg QW, and he was given a course of IV iron for a total of 1 gm. Following transient Hb increase to 9–10g/dL, for few months Hb dropped to 8g/dL and he became transfusion dependent. In addition, he became progressively neutropenic with ANC <500/μL and thrombocytopenic with Plt <50×103/μL. At this point he was initiated on G-CSF 480 μg TIW along with DPO 300 μg QW. One month after the initiation of DPO plus G-CSF his CBC showed WBC 4.0×103/μL, Hb-11.2 g/dL and Plt-92×103/μL. The Plt response was transient and eventually remained stable between 50–60 ×103/μL. He continues to remain transfusion independent after 8 months of combination treatment maintaining Hb between 10–11 g/dL. In addition to having a major erythrocyte and neutrophil response following the initiation of combination treatment of DPO and G-CSF, this patient also had transient Plt response. The course of this patient suggests that the addition of G-CSF to DPO may improve anemia and neutropenia in patients with MDS who do not have a sustained response to DPO alone. In addition it also suggests that in-vivo synergy may exist between DPO and G-CSF for the production of red cells in MDS.

An Open-Label, Unit Dose-Finding Study Evaluating the Safety and Platelet Response of a Novel Thrombopoietic Protein (AMG531) in Thrombocytopenic Adult Patients (Pts) with Immune Thrombocytopenic Purpura (ITP).

This study is an open-label phase 1 study of a novel thrombopoietic agent, AMG531. AMG531 acts through activation of the receptor Mpl to stimulate the growth and maturation of megakaryocytes ultimately resulting in blood platelets (plts). Thrombocytopenic adult pts with ITP were enrolled into sequential cohorts of AMG531 at the assigned unit doses of 30, 100, 300, or 500 μg. There were to be 4 pts per cohort with additional pts in a confirmatory cohort at the selected dose (300 μg). Major eligibility criteria were: diagnosis of ITP as defined by the ASH Guidelines 3 months prior to study entry, baseline platelet (plt) count (ct) <30x109/L (<50x109/L if on corticosteroids), age >18 years and no history of thrombosis. Patients were to receive 2 administrations of AMG531 on study day 1 and 15 (or day 22 if plt cts were >50x109/L on day 15). Follow-up continued for 8 weeks after the last dose for safety. The primary objective was safety and the secondary objectives were related to plt response defined as doubling of baseline plt ct and ≥50x109/L and <450x109/L.Sixteen pts were enrolled into 5 cohorts with the following demographics: 10/16 (63%) females, median age 50 years (range 20–84), 13/16 having had splenectomy (splx). Fourteen of the 16 pts received both administrations of AMG531, and 4 pts received the second dose on day 22. No safety issues or concerns were identified. Headache was the most frequently reported adverse event (AE) in 6/16 (38%) of pts. There were 3 serious AEs reported to be related to AMG531, headache and a transient LDH increase in one pt and thrombocytopenia reported after completing AMG531 in another. Hemoglobin, WBC, blood chemistry and coagulation variables remained stable over the study period and no clinically significant on-study changes were identified. No anti-AMG531 or anti-TPO antibodies were detected. Platelet responses were observed in some pts either the first or second administration in all dose groups. Evaluation of the responses after conversion of the unit (μg) dose to μg/kg demonstrated that in pts that received dose-equivalents of >1 μg/kg, 8/12 (67%) pts achieved the plt response criterion with either the first or the second administration of AMG531. Of these pts with plt responses 6/8 (75%) had previously had a splx. Plt responses were not related to splx status or baseline plt cts. These data suggest that by-weight dosing is appropriate in this pt population and support the need for more frequent dosing.In summary, AMG531 was well tolerated at all doses tested and was capable of increasing plt cts in 67% of pts with ITP when doses equivalent to >1 μg/kg were administered. Future studies will explore the effects of long-term, weekly by-weight dosing with AMG531 to evaluate the durability of this response. These data suggest that stimulation of platelet production with AMG531 in pts with ITP may provide a new treatment option for ITP regardless of splx status.

Single administration of stem cell factor, FLT-3 ligand, megakaryocyte growth and development factor, and interleukin-3 in combination soon after irradiation prevents nonhuman primates from myelosuppression: long-term follow-up of hematopoiesis

AbstractPreservation of hematopoietic stem and progenitor cell survival is required for recovery from radiation-induced myelosuppression. We recently showed that short-term injection of antiapoptotic cytokine combinations into mice soon after lethal gamma irradiation promoted survival. The present study investigated the hematopoietic response of cynomolgus monkeys to a single dose of stem cell factor, FLT-3 ligand, megakaryocyte growth and development factor, and interleukin-3 in combination (4F, each factor given intravenously at 50 μg/kg) administered 2 hours after 5-Gy gamma irradiation. Treated monkeys (n = 4) experienced no thrombocytopenia. Only 1 in 4 displayed a transient period of neutropenia (neutrophil [ANC] count < 0.5 × 109/L), whereas all irradiated controls (n = 4) experienced neutropenia (5-12 days) and thrombocytopenia (platelet [PLT] count < 20 × 109/L, 5-31 days). Treated animals exhibited an impressive 2-wave PLT response that peaked at days 8 and 22 after total body irradiation (TBI). Areas under the curve (AUC) of PLTs, ANCs, white blood cells (WBCs), and red blood cells (RBCs) between days 0 and 90 were significantly higher in treated animals than in controls. Humeral bone marrow–derived clonogenic activity was significantly spared at 24 hours and 4 days after TBI in treated monkeys. No apparent impairment of the hematopoietic status and stem cell pool, in terms of long-term culture–initiating cells (LTC-ICs) and side population (SP) cells, was observed after 15 months. These results strongly suggest that the 4F cytokine combination, as a single dose regimen, could act as an emergency treatment for nuclear accident or terrorism victims.

A posturological study of pseudofistular sign in normal adults and Meniere's patients

A new stabilographical method with pressure loading to the external auditory canal (PLT) was performed in 20 normal subjects and 3 patients with Meniere's disease for the purpose of testing the pseudofistular sign. The pressure ranging from -100mmH2O to +100mmH2O or from -200mmH20 to +200mmH2O were applied to the external auditory canal and the body sways of the center of gravity to the lateral directions for 10 seconds were summated 10 times by a signalprocessor (NEC-sanei, 7TO7A). Positive response was defined as having doubles sway amplitude compaired with the average amplitude of sway without pressure loading.Positive response were observed in seven of twenty normal subjects. These positive reactions were symmetrical in both ears except one case. On the other hand, in cases of Meniere's disease, positive responses were found only in the affected ears. The positive PLT response was not changed at all when the test was repeated in a case of Meniere's disease at the stage of positive response to the grycerol test, however, in another case of Meniere's disease, disappearance of positive PLT response was observed after the puncture of the eardrum.From these findings we considered that the most effective facter of the PLT in producing the deviation was not the pressure change of the middle ear, but the movement of the ossicular chain causing displacement of the foot-plate of stapes.

Genetic and molecular analyses of lymphocyte-defined HLA-D region specificities

Determinants encoded in the HLA-D regin have been studied with both cellular (PLT) and molecular (SDS-IEF) methods. When the PLT response against a lymphoblastoid cell line was analyzed by limiting dilution culture and determination of the reactivity of individual cultures against a panel of loss mutants of the initial stimulating LCL, a large fraction of the cultures showed the same pattern, apparently recognizing a determinant associated with DR. In two-dimensional gel analysis of several DR4-positive HLA-D region homozygous cells, the IEF pattern of the DR beta chain correlated with the Dw specificity expressed by the cell. These two pieces of evidence suggest that, although many determinants may contribute to reactivity in mixed leucocyte culture or PLT, an immunodominant determinant associated with the DR beta chain may be the most important single factor in the assignment of Dw specificity.

The Genetics of PLT Response

Abstract PLT response is restricted by the HLA-D region. The present study was undertaken to help define the role of HLA-DRw in PLT restimulation. Haplotype-primed intrafamily PLT cells were made against specificities HLA-Drw1, HLA-DRw3, and HLA-DRw7; each PLT was then restimulated with cells from a 35-member unrelated panel. Restimulation values for each PLT were subjected to bimodal clustering analysis. In addition, blocking experiments were performed with other intrafamily and homozygous typing cell PLT after preincubation with B cell alloantisera. The results show a high correlation (0.881 ≤ r ≤ 1.00) between the HLA-DRw specificity of the priming haplotype and the HLA-DRw specificity of unrelated panel cells that restimulate in PLT. When stimulating cells were absorbed with the corresponding DRw alloantisera or p29,34 heteroantiserum (against B cell specific antigens), PLT restimulation was significantly blocked. However, the PLT cells treated with antisera showed no effect. The results strongly suggest that HLA-DRw is the principal PLT-stimulating determinant.