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IntroductionClassic differentiation of naive CD4 ϩ T cells into different T helper (Th) subsets, including Th1, Th2, and Th17, occurs in lymphoid tissues after contact with antigen-presenting cells that produce polarizing cytokines. These Th subsets in turn orchestrate diverse immune responses also mediated by production of distinct cytokines. Because aberrant Th1 or Th17 activities have the potential to trigger chronic inflammatory and autoimmune diseases, 1,2 effector Th responses in healthy persons are under tight regulation mediated in part by CD4 ϩ regulatory T cells (Tregs) that are thymic-derived or naive T cell-inducible. 3 Understanding how Th1/Th17/Treg differentiation and expansion are controlled is likely to provide an explanation of how inflammation may be sustained in pathologic environments.More recently, human monocytes were shown to trigger and polarize Th responses 4,5 as well as to both stimulate and suppress T-cell responses during infection and in autoimmune diseases. 5,6 Monocytes, which are generally regarded as precursors of tissue macrophages and dendritic cells, 7 can be phenotypically divided based on surface expression of CD14 (lipopolysaccharide receptor) and CD16 (low affinity Fc␥ receptor III) expression into subsets, each with distinct functional activities. The major monocyte subpopulation characterized by high CD14 but no CD16 expression (CD14 hi CD16 Ϫ ), also referred to as classic monocytes, have higher phagocytic activity. 8 The minor CD16 ϩ cells produce higher TNF after stimulation and expand under infectious or inflammatory conditions. 9,10 With regards to the control of Th differentiation and reactivation, the specific role of the monocyte subsets has not been fully characterized.Immune thrombocytopenia (ITP) is an autoimmune bleeding disease resulting from decreased platelet production as well as accelerated platelet destruction mediated in part by autoantibody-based destruction mechanisms. 11 ITP patients harbor activated platelet-autoreactive T cells with increasing cytokine imbalance toward IL-2 and IFN-␥ 12-14 as well as altered Treg numbers and function. [15][16][17][18][19][20] A shift toward stimulatory monocytes with enhanced Fc␥R-mediated phagocytic capacity further supports a generalized immune dysregulation in ITP. 21 More recently, studies reported increased Th17 cells or IL-17 cytokine in ITP patients, 22-24 implicating a possible role for Th17 cells in ITP immunopathology, although 2 reports did not detect any difference. 25,26 Among the treatment options available to ITP patients, the recently licensed thrombopoietic agents, by increasing platelet production, have yielded overall durable responses in patients with persistent, chronic, and/or refractory ITP while on treatment. 27 Interestingly, improved Treg function in ITP patients was associated with increased platelet counts after the use of these agents, 28 despite apparent lack of immunomodulatory activity associated with such agents. Similarly, improved Treg compartment was reported in ITP patients w...

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The nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) fusion is the product of the t(2;5)(p23;q35) chromosomal translocation found in approximately half of anaplastic large cell lymphomas (ALCL). Moreover, this fusion kinase, as well as other ALK fusion proteins, have been found in large B-cell lymphomas. This fusion kinase has been shown to regulate multiple signal transduction pathways and to induce hematopoietic malignancy in murine models. Nonetheless, the functional role of signaling events caused by NPM-ALK expression is incompletely understood. Here we report that NPM-ALK activates the kinase S6K1 (p70/p85) and the extracellular regulated kinase (ERK1/2). In Ba/F3 murine hematopoietic cells that express NPM-ALK, S6K1 activition by NPM-ALK was sensitive to mTOR inhibition by rapamycin. However, treatment of NPM-ALK-Ba/F3 cells with the MEK inhibitor UO126 did not attenuate the activation of S6K1 by NPM-ALK. Pharmacological inhibition of either mTOR or MEK in Ba/F3 cells expressing NPM-ALK resulted in impaired cytokine-independent outgrowth of these cells. For either inhibitor, suppression of cytokine-independent outgrowth was due to impairment of cell proliferation. In contrast, cell survival signaling was not compromised by either inhibitor alone or in combination. Combined inhibition of both the mTOR/S6K1 and MEK/ERK signaling modules resulted in an additive impairment of cytokine-independent outgrowth. Moreover, rapamycin attenuated the proliferation of the human NPM-ALK-expressing ALCL cell line Karpas299. The mTOR/S6K1 and MEK/ERK signaling modules may serve as effective chemotherapeutic targets in the treatment of ALCL and other malignancies that express the activated ALK protein tyrosine kinase.

Background Eltrombopag is an oral thrombopoietin receptor agonist which increases platelet counts in immune thrombocytopenia (ITP) patients by increasing proliferation of megakaryocyte (Mk) precursors and Mk. Maximal approved eltrombopag dosage in chronic ITP patients is 75mg daily, yet some patients do not respond at this dose. In a prior 6-week study, a numerically higher proportion of patients responded at 75mg vs. 50mg. Data of the pharmacokinetics, safety and tolerability of eltrombopag in healthy volunteers at an escalated dosage (100-200mg) showed a dose dependent platelet response. Doses > 75mg have been used in other settings without additional toxicity, including Aplastic Anemia and Chronic Hepatitis C associated thrombocytopenia. Taken in conjunction, a higher eltrombopag dose may be effective in treating ITP in non-responders without increased toxicity. The following double blind, randomized controlled study is in progress to determine if eltrombopag administered at up to 150mg daily increases platelet counts and lessens bleeding symptoms in ITP patients who failed to respond to 75 mg. Methods Non-responders (patients ≥ 12 years old with platelet counts<50,000 μL despite 3 weeks of 75mg of eltrombopag daily), stratified by splenectomy status, were enrolled into a double blind randomized controlled study. Patients were allowed to continue stable doses of concomitant medications at randomization. In Part 1 (blinded phase), all patients received 75 mg of eltrombopag with the addition of 25 mg of study drug (eltrombopag or placebo). Every two weeks, doses were increased in 25 mg increments to a maximum daily dose of 150mg. After 8 weeks subjects were unblinded. If on active drug, they can enter the open label (Part 2) phase; or if previously on placebo, subjects may receive open label eltrombopag as per the study protocol to a maximal daily dose of 150mg. Subjects are considered complete responders (CR) with 2 consecutive platelet counts >50,000 μL AND an overall increase from baseline >20,000 μL not attributable to rescue therapy in the 8 weeks from initiating dose escalation. Subjects are considered partial responders (PR) if they have 2 consecutive platelet counts of >50,000 μL OR an overall increase from baseline >20,000 μL not attributable to rescue therapy by 8 weeks (figure). Monitoring includes baseline cataract exams with additional eye exams at 6 and 18 months, bleeding evaluations every 2 weeks (Part 1) and bone marrow biopsy after 1 year (Part 2). Results 13 patients (2 adolescents and 11 adults) have been enrolled in the study. Of the 5 adult patients who completed ≥ 8 weeks on active medication, 3 achieved either CR (1) or PR (2). The 2 PRs had an increase from baseline to highest count ranging from 23-47,000 μL. 2/3 responders achieved higher platelet counts in the open label extension phase suggesting a longer term slow onset effect of eltrombopag. One PR decreased her daily prednisone dose from 30 mg to 10 mg, with platelet count fluctuations attributed to dietary guideline non-adherence. As of August 8, 6 patients are in Part 1, 4 patients are in Part 2, and 3 have been removed from the study (one patient had elevated transaminases in Part 2, week 12; one patient had pre-existing reticulin fibrosis 2-3+ without clinical symptoms. This pre-study bone marrow result was not available at randomization, but the patient was withdrawn prior to any study drug administration. She had previously received treatment with two other TPO agents; the third patient withdrew secondary to increased bleeding symptoms while on the placebo arm). Other adverse events related to eltrombopag have been mild or moderate. Rescue therapies include intravenous immunoglobulin (IVIG) and prednisone. Most patients have had pre-treatment or recent bone marrows biopsies with a follow up biopsy planned after one year of treatment at 150mg. Conclusions To date, the results demonstrate moderate responses to eltrombopag at increased doses to 150mg daily in the 3 responding patients who have been treated the longest. One subject achieved a CR and two a PR. Three subjects were removed for toxicity but in one it was for marrow findings that antedated study enrollment and another for bleeding while receiving placebo therapy. Interim analysis will be performed after 20 enrolled patients and younger patients might enter the study following completion of ongoing eltrombopag studies in pediatric patients with chronic ITP. Disclosures: Bussel: Ligand: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Shionogi: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Sysmex: Research Funding; Eisai: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Immunomedics: Research Funding; IgG of America: Research Funding; Genzyme: Research Funding; Cangene: Research Funding; GlaxoSmithKline: Equity Ownership, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Amgen: Equity Ownership, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Symphogen: Membership on an entity’s Board of Directors or advisory committees.