Sirolimus plus prednisolone vs sirolimus monotherapy for kaposiform hemangioendothelioma: a randomized clinical trial

The Kasabach-Merritt phenomenon (KMP) in kaposiform hemangioendothelioma (KHE) is characterized by life-threatening thrombocytopenia and consumptive coagulopathy. This study compared the efficacy and safety of sirolimus plus prednisolone versus sirolimus monotherapy as treatment strategies for KHE with KMP in the largest cohort to date. Participants were randomized to receive either sirolimus in combination with a short course of prednisolone or sirolimus monotherapy for at least 12 months. The primary outcome was defined as achievement of a durable platelet response (platelet count >100×109/L) at week 4. Participants completed efficacy assessments 2 years after the initial treatment. At week 4, a durable platelet response was achieved by 35 of 37 patients given sirolimus and prednisolone compared with 24 of 36 patients given sirolimus monotherapy (difference 27.9%; 95% CI, 10.0% to 44.7%). Compared with the sirolimus monotherapy group, the combination treatment group showed improvements in terms of measures of durable platelet responses at all points during the initial 3-week treatment period, median platelet counts during weeks 1 to 4, increased numbers of patients achieving fibrinogen stabilization at week 4, and objective lesion responses at month 12. Patients receiving combination therapy had fewer blood transfusions and a lower total incidence of disease sequelae than patients receiving sirolimus alone. The frequencies of total adverse events and grade 3-4 adverse events during treatment were similar in both groups. The responses seen in patients with KHE with KMP were profound and encouraging, suggesting that sirolimus plus prednisolone should be considered a valid treatment for KHE with KMP. ClinicalTrial.gov, number NCT03188068

Romiplostim for Primary Immune Thrombocytopenia (ITP) in Routine Clinical Practice: Results from a Multicentre Observational Study in Germany

Introduction: The effectiveness and safety of romiplostim were evaluated by immune thrombocytopenia (ITP) phase (newly diagnosed/persistent/chronic) at romiplostim initiation. Methods: Post hoc analysis of a prospective, German, multicentre, observational study in adults with ITP who received ≥1 dose of romiplostim. Follow-up data were collected for ≤2 years. Outcomes included overall platelet response (≥1 platelet count ≥50 × 109/L at 2–24 weeks after romiplostim initiation) or durable platelet response (≥75% of measurements ≥50 x 109/L at 14–24 weeks), and adverse drug reactions (ADRs), evaluated by ITP phase. Results: Data from 96 patients were analysed (newly diagnosed, n=18; persistent, n=25; chronic, n=53). During the 2–24-week follow-up, overall platelet response was achieved in 100% (95% confidence interval [CI]: 81.5–100), 100% (86.3–100), and 96.2% (87.0–99.5) of patients with newly diagnosed, persistent, or chronic ITP, respectively; platelet responses were durable in 88.2% (63.6–98.5), 65.0% (40.8–84.6), and 69.4% (54.6–81.7) of patients. During the 2-year follow-up, ADRs occurred in 24.0–35.8% of patients across phases. Two patients with chronic ITP experienced bone marrow ADRs; no thrombotic ADRs occurred. Conclusion: Romiplostim was effective and well tolerated in patients with newly diagnosed, persistent, or chronic ITP in routine clinical practice.

Platelet ACKR3/CXCR7 Favors Anti-Platelet Lipids over an Atherothrombotic Lipidome and Regulates Thrombo-inflammation

Platelet ACKR3/CXCR7 surface expression is enhanced and influences prognosis in coronary artery disease-(CAD) patients, who exhibit a distinct atherothrombotic platelet lipidome. Current investigation validates the potential of ACKR3/CXCR7 in regulating thrombo-inflammatory response, through its impact on the platelet lipidome. CAD patients-(n=230) with enhanced platelet-ACKR3/CXCR7 expression exhibited reduced aggregation. Pharmacological CXCR7-agonist-(VUF11207) significantly reduced pro-thrombotic platelet response in blood from ACS patients-(n=11) ex vivo. CXCR7-agonist administration reduced thrombotic functions and thrombo-inflammatory platelet-leukocyte interactions post myocardial infarction-(MI) and arterial injury in vivo. ACKR3/CXCR7-ligation did not affect surface availability of GPIbα, GPV, GPVI, GPIX, αv-integrin, β3-integrin, coagulation profile-(APTT, PT), bleeding time, plasma-dependent thrombin generation-(thrombinoscopy) or clot formation-(thromboelastography), but counteracted activation-induced phosphatidylserine exposure and procoagulant platelet-assisted thrombin generation. Targeted-(micro-UHPLC-ESI-QTrap-MS/MS) and untargeted-(UHPLC-ESI-QTOF-MS/MS) lipidomics analysis revealed that ACKR3/CXCR7-ligation favored generation of anti-thrombotic lipids-(dihomo-γ-linolenic acid-DGLA, 12-hydroxyeicosatrienoic acid-12-HETrE) over cyclooxygenase-COX-1-(thromboxane-TxA2), or 12-lipoxygenase-LOX-(12-HETE) metabolized pro-thrombotic, and phospholipase derived atherogenic-(lysophosphatidylcholine-LPC) lipids, in healthy subjects and CAD patients, contrary to anti-platelet therapy. Through 12-HETrE, ACKR3/CXCR7-ligation coordinated with Gαs-coupled prostacyclin receptor-(IP) to trigger cAMP-PKA mediated platelet inhibition. ACKR3/CXCR7-ligation reduced generation of lipid agonists-(arachidonic acid-AA,TxA2), lipid signaling intermediates-(lyophosphatidylinositol-LPI, diacylglycerol-DG), which affected calcium mobilization, intracellular signaling, consequently platelet interaction with physiological matrices and thrombo-inflammatory secretion-(IL1β,IFN-γ,TGF-β,IL-8), emphasizing its functional dichotomy from pro-thrombotic CXCR4. Moreover, CXCR7-agonist regulated heparin-induced thrombocytopenia-(HIT)-sera/IgG-induced platelet and neutrophil activation, heparin induced platelet aggregation-(HIPA), generation of COX-1-(TxA2), 12-LOX-(12-HETE) derived thrombo-inflammatory lipids, platelet-neutrophil aggregate formation, and thrombo-inflammatory secretion (sCD40L, IL-1β, IFN-γ, TNF-α, sP-selectin, IL-8, tissue factor-TF) ex vivo. Therefore, ACKR3/CXCR7 may offer a novel therapeutic strategy in acute/chronic thrombo-inflammation exaggerated cardiovascular pathologies, and CAD.

Real-World Use of Fostamatinib in Patients with Immune Thrombocytopenia and Thrombotic Risk

Patients with immune thrombocytopenia (ITP) are at increased risk for bleeding and are paradoxically at increased risk for thrombosis. Many patients with ITP have underlying cardiovascular (CV) disease and/or other thrombotic risk factors for which considerable attention to selecting a therapeutic agent to manage ITP is needed. Fostamatinib, a spleen tyrosine kinase inhibitor, may reduce the risk of thrombosis while not interfering with hemostasis. We present a case series of 5 patients with ITP who had significant CV histories; each had at least 2 thrombotic risk factors. After unsuccessful management of ITP with other treatments, fostamatinib was initiated, was observed to be tolerable, and provided a durable platelet response without associated thromboembolic events. Fostamatinib may be the treatment of choice for patients with ITP in whom use of prothrombotic treatments should be avoided and/or continued use of antiplatelet or anticoagulant medication is needed.

RASopathies and hemostatic abnormalities: key role of platelet dysfunction

Background Bleeding anomalies have been reported in patients affected by Noonan syndrome. No study has been performed in patients with molecularly confirmed RASopathy. We aimed to characterize the frequency and types of bleeding disorders in patients with RASopathies and evaluate any significant association with laboratory findings. Patients and methods Forty-nine individuals (PTPN11, n = 27; SOS1, n = 7; RIT1, n = 3; SPRED1, n = 1; LZTR1, N = 3; RAF1, n = 2; BRAF, n = 4; MEK1, n = 1; MEK2, n = 1), and 49 age- and sex-matched controls were enrolled. The “Paediatric Bleeding Questionnaire Scoring Key” was administered to patients and families. Laboratory screening tests including clotting factors dosing, platelet count, Prothrombin Time and Partial Thromboplastin Time, were employed both in patients and controls to characterize the bleeding diathesis. A subgroup of 29/49 patients and 29/49 controls was also tested for platelet function. Results Regardless of the gene involved, pathological paediatric bleeding scores were recorded in 14/49 (28.5%) patients. Indeed, 7 were mutated in PTPN11, 3 in SOS1, 2 in RIT1, 1 in BRAF, and 1 in MEK1. Compared to patients with normal bleeding scores, those with pathologic bleeding score showed higher prevalence of splenomegaly (p = 0.006), prolonged aPTT (p = 0.04), lower levels of coagulation factor V (FV, p = 0.001), FVII (p = 0.003), FX (p = 0.0008) and FXIII (p = 0.002), higher vWAg (p = 0.04), and lower platelet sensitivity to Ristocetin (p = 0.001), arachidonic acid (AA) (p = 0.009) and collagen (p = 0.01). The presence of hematomas inversely correlated with factor V (p = 0.002), factor VII (p = 0.003), factor X (p = 0.002) and factor XIII (p = 0.004) levels, and directly correlated with platelet response to collagen (p = 0.02) and AA (p = 0.01). The presence of splenomegaly directly correlated with the presence of hematoma (p = 0.006), platelet response to Ristocetin (p = 0.04) and AA (p = 0.04), and inversely correlated with factor V levels (p = 0.03). Conclusions Patients with RASopathies and a bleeding tendency exhibit multiple laboratory abnormalities, including platelet-related disorders. Splenomegaly is frequently detected and might be a suggestive sign for qualitative platelet dysfunction. A comprehensive clinical assessment should be carried out at diagnosis, during the follow-up and before any surgical procedures. Since there is currently no consensus on management of bleeding complications, it is important that physicians closely monitor these patients.

Evaluation of the equivalence of different intakes of Fruitflow in affecting platelet aggregation and thrombin generation capacity in a randomized, double-blinded pilot study in male subjects

Background The water-soluble tomato extract, Fruitflow® is a dietary antiplatelet which can be used to lower platelet aggregability in primary preventative settings. We carried out a pilot study to investigate the range of intakes linked to efficacy and to make an initial assessment of variability in response to Fruitflow®. Methods Platelet response to adenosine diphosphate (ADP) agonist and thrombin generation capacity were monitored at baseline and 24 h after consuming 0, 30, 75, 150 or 300 mg of Fruitflow® in a randomized, double-blinded crossover study in male subjects 30–65 years of age (N = 12). Results were evaluated for equivalence to the standard 150 mg dose. Results Results showed that the changes from baseline aggregation and thrombin generation observed after the 75 mg, 150 mg, and 300 mg supplements were equivalent. Aggregation was reduced from baseline by − 12.9 ± 17.7%, − 12.0 ± 13.9% and − 17.7 ± 15.7% respectively, while thrombin generation capacity fell by − 8.6 ± 4.1%, − 9.2 ± 3.1% and − 11.3 ± 2.3% respectively. Effects observed for 0 mg and 30 mg supplements were non-equivalent to 150 mg and not different from baseline (aggregation changed by 3.0 ± 5.0% and − 0.7 ± 10.2% respectively, while thrombin generation changed by 0.8 ± 3.0% and 0.8 ± 3.1% respectively). Conclusions The data suggest that the efficacious range for Fruitflow® lies between 75 mg and 300 mg, depending on the individual. It may be pertinent to personalize the daily intake of Fruitflow® depending on individual platelet response. Trial registration ISRCTN53447583, 24/02/2021.

Loss of zinc transporters ZIP1 and ZIP3 augments platelet reactivity in response to G protein-coupled receptor agonists and accelerates thrombus formation in vivo

Zinc (Zn2+) is considered as an important mediator for thrombosis and haemostasis. However, our understanding of the transport mechanisms that regulate Zn2+ homeostasis in platelets is limited. Zn2+ transporters, ZIPs and ZnTs, are widely expressed in eukaryotic cells. Using mice globally lacking ZIP1 and ZIP3 (ZIP1/3 DKO), our aim was to explore the potential role of these well-known Zn2+ transporters in maintaining platelet Zn2+ homeostasis and in the regulation of platelet function. While ICP-MS measurements indicated unaltered overall Zn2+ concentrations in platelets of ZIP1/3 DKO mice, we observed a significantly delayed and less efficient Zn2+ release upon thrombin-stimulated platelet activation. This resulted in a hyperactive platelet response not only in response to thrombin, but also towards other G protein-coupled receptor (GPCR) agonists. Immunoreceptor tyrosine-based activation (ITAM)-coupled receptor agonist signalling, however, was unaffected. Augmented GPCR responses were accompanied by enhanced Ca2+ signalling and PKC activation. Further functional analysis of ZIP1/3 double deficient mice revealed enhanced platelet aggregation, bigger thrombus volume under flow ex vivo and faster in vivo thrombus formation. The current study thereby identifies ZIP1 and ZIP3 as important regulators for the maintenance of platelet Zn2+ homeostasis and function.

Safety and Efficacy of Thrombopoietin Analogs in the Treatment of Chronic Thrombocytopenic Purpura in Children: A Systematic Review

Introduction Immune thrombocytopenic purpura (ITP) is an autoimmune disorder consisting of low platelet count, purpura, and hemorrhagic episodes, caused by antiplatelet autoantibodies. Children who develop chronic or refractory ITP are at risk of bleeding after failing first-line therapies. Thrombopoietin analogs -Eltrombopag and romiplostim are safe and effective treatment options. Thrombopoietin receptor agonists (TPO-Ras) improve platelet production by activating the thrombopoietin pathway. They also stimulate megakaryocytes and hematopoietic stem cells. We analyzed the efficacy and toxicity of romiplostim and eltrombopag in chronic immune thrombocytopenic purpura in the pediatric population (1-17 years). Materials/Methods Following the PRISMA guidelines, we performed a comprehensive literature search on Pubmed, Embase, Cochrane Library, Web of Science, and Clinicaltrials.gov. We used the following keywords, "Thrombopoitein analogs", "TPOs", "Immune thrombocytopenic purpura", "Eltrombopag" and "Romiplostim" MeSh terms from the inception of data till 06/17/2021. We screened initial results from the search of 358 articles focusing on the pediatric population and finally included 9 clinical trials and 1 observational study. We excluded all case reports, case series, preclinical trials, review articles, and meta-analyses. We extracted the data for efficacy (platelet response, baseline platelet count, and Platelet count at first response) and safety (Bleeding or Grade ≥ 3 Adverse Events). Results: Romiplostim A total of 185 patients were analyzed in five clinical trials and 1 observational study employing Romiplostim in the treatment group. Platelet response (PR) (platelet count >50 × 109/L) has been reported in all the studies. In 3 randomized double-blinded control trials by Bussel 2011, Elfaly 2011, and Tarantino 2016, Romiplostim achieved a platelet response of 81.69% vs 12.9% in the placebo group. The other three studies reported substantial platelet response as stated in table 1. In all the studies 25 participants had a prior splenectomy. The most common side effects reported in the studies were bleeding (56.75%), headache (58.64%), contusion (50.76%), and epistaxis (49.23%). Clinically significant bleeding (grade 2-4) was reported by 2 studies in Romiplostim vs placebo group (71.08% vs 96%). Eltrombopag A total of 246 patients were analyzed in five clinical trials and 1 observational study. In a randomized double-blinded multicenter study by Grainger et al., Eltrombopag achieved a PR of 39.68% vs 3.4% in the placebo group. Other clinical trials reported a PR of 55.85% whereas the observational study by Neuner et al. reported a PR of 72% in the patient population. Clinically significant bleeding was reported by Grainger et al. and was 47 % in the eltrombopag group vs 7% in the placebo group. Fifteen patients in all the studies had a prior splenectomy. Conclusion: Thrombopoietin analogs such as romiplostim and eltrombopag show substantial platelet response and are associated with minimal side effects. However, more randomized clinical trials are needed to compare their head-to-head efficacy and safety in the treatment of chronic immune thrombocytopenic purpura in pediatric patients. Figure 1 Figure 1. Disclosures Anwer: Janssen pharmaceutical: Honoraria, Research Funding; GlaxoSmithKline: Research Funding; Allogene Therapeutics: Research Funding; BMS / Celgene: Honoraria, Research Funding.