Management of symptoms and prevention of life-threatening haemorrhage in Immune thrombocytopenia (ITP) must be balanced against adverse effects of available therapies. Since current treatment guidelines based on platelet count are confounded by variable bleeding phenotypes, there is a need to identify new objective markers of disease severity for improved treatment stratification. In this cross-sectional, prospective study of 49 patients with ITP and lowest recorded (nadir) platelet counts below 30 x 109/L, we used Susceptibility-Weighted Magnetic Resonance Imaging (SWI) to detect cerebral microbleeds (CMBs) as a marker of occult haemorrhage. CMBs were detected using a semi-automated method and correlated with clinical metadata using multivariate Poisson regression analysis. Lobar CMBs were identified in 43% (21/49); prevalence increased with decreasing nadir platelet count (15/25 <5x109/L; 4/11 5-9x109/L; 2/9 10-14x109/L; 0/4 >15x109/L), and was associated with longer disease duration (p=7x10-6), lower nadir platelet count (p=0.005), lower platelet count at time of MRI (p=0.029), and higher organ bleeding scores (p=0.028). Mucosal and skin bleeding scores, number of previous treatments, age and sex were not associated with CMBs. Occult cerebral microhaemorrhage is common in patients with moderate to severe ITP. Strong associations with ITP duration may reflect CMB accrual over time or more refractory disease. Although associated, neither low platelet count or bleeding scores predict CMBs. SWI could therefore provide an additional non-invasive biomarker of haemorrhagic phenotype, and potential adjunct for treatment stratification. Further longitudinal studies in children and adults will allow greater understanding of the natural history, and clinical and prognostic significance of CMBs.
Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by a skewed proinflammatory T cell profile. Thrombopoietin-receptor agonists (TPO-RA) have largely replaced immunosuppressants in the management of this disorder, with some patients achieving remission after a period of treatment with TPO-RA. The potential immune modulatory role of TPO-RA has not been fully investigated. The two current TPO-RA licensed for use in ITP; Eltrombopag (Elt) and Romiplostim (Romi) act on different parts of the TPO-R and have similar response rates. However, patients can respond to one agent but not the other. Elt has been described to have a strong iron chelating effect, and hence we propose that it may have an additive immunomodulatory effect on the T cells, absent in Romi. We determined the immunomodulatory effect of Elt by assessing the proliferation and functionality of T-cell lines and primary T-cells. T cell proliferation was assessed using both CFSE proliferation assay and MTT cell viability assay. T cell phenotype and functionality were assessed by multicolor surface and intracellular flow cytometric staining. Cells were co-cultured with Elt and Romi in vitro and ex vivo with both Jurkat and DG75 cells lines as well as primary cells, respectively. Deferoxamine (DFX) was used as a positive control for iron-chelation, and human TPO was used as a positive control for TPO-RA. All treatment doses were based on their calculated therapeutic serum levels. Mann Whitney U and Kruskal-Wallis H statistical tests were applied where applicable, and a P value of less than 0.05 were considered significant. Elt significantly decreased Jurkat T cells proliferation in a dose-dependent manner compared to no treatment and Romi. DFX, an iron chelator, also decreased Jurkat T cell proliferation to comparable levels of Elt. Interestingly, this anti-proliferative effect of Elt was only observed on Jurkat T cells, but not DG75 B cell line. Ex vivo CFSE proliferation assay was performed on primary CD4 and CD8 T cells assessing the antiproliferative effect of Elt. Elt significantly reduced proliferation compared to no treatment. DFX exhibited a similar antiproliferative effect on primary T cells, however, less potent compared to Elt. Neither Romi nor TPO affected the proliferation of Jurkat cells, DG75 cells or primary T cells. The functionality of CD4 and CD8 T cells was assessed based on the capacity of T cells to produce intracellular TNFα, IFNγ and Granzyme B. Elt significantly reduced the percentages of TNFα+/IFNγ+ CD4+ and CD8+ T cells in a dose-dependent manner. This reduction was also observed, albeit to a lesser extent, when T cells were treated with DFX. Furthermore, Granzyme B expression in CD8+ T cells was significantly reduced when cells were treated Elt, compared to no treatment. Romi did not affect the frequency of CD8+ TNFα+/IFNγ+ populations nor the expression of Granzyme B in CD8+ T cells. CD4+ and CD8+ T cells did not express TPO-R on their surface. To confirm the immunomodulatory role of Elt in vivo, the terminally-differentiated effector (CD45RA+CD62L-) CD8+ T cells were assessed in 13 Elt-treated patients and 11 Romi-treated patients. Patients on Elt had significantly reduced frequency of effector CD8 T cells compared to Romi-treated patients (44% vs 76.8%; p<0.01). Taken together, these novel findings suggest an off target immunomodulatory nature of Elt besides its thrombopoietic effect. This dose-dependent immunomodulatory effect is not TPO-R dependent and targets T cells primarily. This study is the first to display such property of Elt and could explain why there is a differential response to Elt and Romi. We hypothesise that Elt may be more effective in patients with T cell mediated disease, whilst patients with predominantly antibody mediated disease are more likely respond to Romi. These findings can also offer an explanation for Elt effectiveness in other T cell-mediated autoimmune conditions such as Aplastic Anemia. Disclosures Cooper: Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Rigel: Consultancy, Membership on an entity's Board of Directors or advisory committees; Principia: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees.
Background: The anti-CD52 monoclonal antibody alemtuzumab (Alem) induces a rapid-onset, profound and long-lasting depletion of lymphocytes: B cells recover within 12 months, while T cell recovery is still incomplete after 30 months. Alem is used as induction therapy for solid organ transplantations, including renal. Autoimmune complications following Alem include thyroid disorders (20-30%), immune thrombocytopenia (ITP) (2-3%), and autoimmune hemolytic anemia (AIHA) and autoimmune nephropathies (< 1%). Methods: we retrospectively analyzed 41 patients (pts) attending the Haematology Clinic at Hammersmith Hospital (HH), who developed autoimmune cytopenias (ITP or AIHA) after an Alem-induced renal transplant. The autoimmune cytopenia was defined as a rapid onset of isolated thrombocytopenia and/or anemia without other explanation. For ITP, complete response (CR) and response (R) were defined according to IWG standard criteria (Rodeghiero,Blood,2009). For AIHA, CR was defined as a stable Hb level >120 g/L, no transfusion requirement and no signs of hemolysis; partial response (PR) as a rise in Hb levels >20 g/L, without transfusion requirement. The study aim is to report clinical features and treatment outcomes of these 41 pts. Results: Between 1/11/05 and 14/12/16, 1431 pts received an Alem-induced renal transplant at HH. 34 (2.3%) developed ITP and 7 (0.48%) AIHA; 28 (68%) pts were males. Median age at renal transplant was 48 (range 20-69) years. The cytopenia developed a median of 35 months (range 6-161) after Alem administration. Median lowest platelet count was 5.5x109/L (range 0-41) and median nadir of hemoglobin (Hb) was 58 g/L (range 35-65). ITP pts: 2 pts achieved spontaneous CR. Of the remaining 32, 91% received steroids, IVIG or both as first line therapy, with an overall response rate (ORR) of 62%. 10 pts (31%) maintained the response without any further treatment. 22 pts required second line therapy, 11 required ≥ 3 lines of treatment. Treatments included: thrombopoietin receptor agonists (TPO-RA), rituximab (RTX), MMF and/or a combination. TPO-RA were used 15 times, with an ORR of 80%, a relapse rate of 33% and a median duration of response (DOR) of 22 months (range 3-48); 10/12 pts (83%) who responded to TPO-RA, discontinued treatment after a median of 64 days (range 7 - 528): 6 maintained the response after discontinuation. RTX was used 10 times, with an ORR of 90%, a relapse rate of 22% and a median DOR of 27 months (range 3 - 83). A combination of RTX and TPO-RA was used 7 times, with an ORR of 71%, a relapse rate of 40% and a median duration of response (DOR) of 5 months (range 2-44); the 5 responders discontinued treatment after a median of 49 days (range 14-462): 3/5 maintained their response. After a median follow-up of 38 months (range 3-96), all ITP pts maintained a response (91% CR and 9% R); 4 were still on treatment (2 TPO-RA and 2 MMF). AIHA pts: 6 of 7 (86%) pts with AIHA received first line steroids +/- IVIG with an ORR of 67%. 4 pts needed second line therapy: all received RTX with an ORR of 50%. 2 pts needed ≥ 3 lines of therapy. After a median follow-up of 68 months (range 27-102) all AIHA pts maintained a response (57% CR and 43% PR), without any ongoing treatment. Adverse events: 33 pts (80%) experienced 1 or more adverse events (AEs): 25 cardiovascular (including 14 thrombosis), 21 infections (16 grade ≥3), 5 steroid-induced diabetes, 3 graft failures, 10 malignancies (6 solid tumors and 4 PTLD). 6 of the ITP pts also developed AIHA (Evans syndrome). 3 ITP pts died. Conclusions: ITP and AIHA represent important complications of Alem-induced renal transplant. Response rates after first-line therapy for ITP were comparable to primary ITP (30%). However, long-term response rate, sustained response to RTX and the proportion of pts able to continue in remission after discontinuing TPO-RA are higher than seen with primary ITP. Recovery from cytopenias may occur in conjunction with T cell reconstitution post Alem (this is under investigation). The large majority of AEs were related to multifactorial heavy immunosuppression and increased thrombotic risk distinguishing this group of pts. Hence for ITP and AIHA, steroids should be limited, as they are curative in only a few pts and burdened by many side effects. Both RTX and a short course of TPO-RA appear valid options, but the choice should be driven by the individual balance between thrombotic and infectious risks versus persistence of cytopenias. Disclosures Cooper: Amgen, Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees.
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