Insights from the Hereditary Thrombotic Thrombocytopenic Purpura Registry: Discussion of Key Findings Based on Individual Cases from Switzerland.

The Hereditary TTP Registry is an international cohort study for patients with a confirmed or suspected diagnosis of hereditary thrombotic thrombocytopenic purpura (hTTP) and their family members. Hereditary TTP is an ultra-rare blood disorder (prevalence of ∼1-2 cases per million), the result of autosomal-recessively inherited congenital ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) deficiency (ADAMTS13 activity <10% of the normal), and associated with yet many unanswered questions. Until December 2017, the Hereditary TTP Registry had enrolled 123 confirmed hTTP patients. Their median age at disease onset was 4.5 years (range: 0-70) and at clinical diagnosis 16.7 years (range: 0-69), a difference that highlights the existing awareness gap in recognizing hTTP. The systematic collection of clinical data of individual patients revealed their substantial baseline comorbidities, as a consequence of recurring TTP episodes in the past. Most notable was the high proportion of patients having suffered from premature arterial thrombotic events, mainly transient ischemic attacks, ischemic strokes, and to a lesser extent myocardial infarctions. At 40 to 50 years of age and above, more than 50% of patients had suffered from at least one such event, and many had experienced arterial thrombotic events despite regular plasma infusions every 2 to 3 weeks that supplements the missing plasma ADAMTS13. The article by van Dorland et al. (Haematologica 2019;104(10):2107-2115) and the ongoing Hereditary TTP Registry cohort study were recognized with the Günter Landbeck Excellence Award at the 50th Hemophilia Symposium in Hamburg in November 2019, the reason to present the Hereditary TTP Registry in more detail here

Using digital RNA counting and flow cytometry to compare mRNA with protein expression in acute leukemias

The diagnosis of malignant hematologic diseases has become increasingly complex during the last decade. It is based on the interpretation of results from different laboratory analyses, which range from microscopy to gene expression profiling. Recently, a method for the analysis of RNA phenotypes has been developed, the nCounter technology (Nanostring® Technologies), which allows for simultaneous quantification of hundreds of RNA molecules in biological samples. We evaluated this technique in a Swiss multi-center study on eighty-six samples from acute leukemia patients

Correlation of flow cytometric and nCounter results.

<p><b>A:</b> Correlation between results from the nCounter technology and flow cytometry for four typical antigens. Flow cytometric results are given as percentage of cells positive for a given antigen, and nCounter results as digital counts (after normalization and background subtraction). The number of depicted data points varies depending on the antigen tested and on the availability of both cytometric and nCounter values for a given sample. Only samples for which both values were measured are shown. Some samples, particularly informative for a particular antigen, were highlighted with dots in different shades and patterns. nBM, normal bone marrow; corr coeff, Pearson’s correlation coefficient. corr coeff >0.393 are statistically significant with p<0.01. <b>B:</b> Correlation between % of leukemic blasts as determined by flow cytometry, and nCounter values for two typical antigens (CD34, CD19).</p

Analysis of mRNA expression of thirteen B cell specific antigens in seven different cell populations isolated from peripheral blood.

<p>For each antigen the columns from left to right correspond to CD4+ T-cells (dark gray), CD8+ T-cells (light gray), NK cells (white), CD19+ B-cells (black), CD14+ monocytes (light gray), CD33+ neutrophils (gray), and eosinophils (dark grey).</p

Correlation coefficient for flow cytometry (protein) and nCounter (mRNA) values from 22 antigens.

<p>Pearson’s correlation coefficient between nCounter signal intensity and percentage of positive cells measured by flow cytometry. Twenty-two different antigens were analyzed in seventy-three samples (11 normal bone marrow, 5 normal peripheral blood, 8 sorted cell populations, 45 acute leukemia, 2 CLL, and 2 CML).</p><p>corr coeff >0.302 are statistically significant with p<0.01.</p

Analysis of leukemic blasts: correlation between results from flow cytometry and nCounter analysis for twenty-two different antigens, each studied in forty-five leukemia patients.

<p>corr coeff >0.372 are statistically significant with p<0.01.</p

Comparative analysis of leukemia patients.

<p><b>A:</b> Comparison of nCounter values from normal BM ( =  the mean of the values from eleven normal BM samples) with a sample from a patient with acute myeloid leukemia. Values in the acute leukemia sample, which were above the normal BM mean +2SD, were considered positive (light rectangles) and the corresponding mRNA expressed by the leukemic blasts. <b>B:</b> Correlation between % of blasts present in a leukemic sample and concordance between flow cytometry and nCounter results in forty-six patients.</p

Intravenous Immunoglobulins Tapering and Withdrawal in Systemic Capillary Leak Syndrome (Clarkson Disease)

International audienceBackground: The systemic capillary leak syndrome (SCLS), also known as Clarkson disease, is a very rare condition characterized by recurrent life-threatening episodes of vascular hyperpermeability in the presence of a monoclonal gammopathy. Extended intravenous immunoglobulin (IVIG) treatment is associated with fewer recurrences and improved survival, but the optimal treatment dosage and duration remain unknown. Objective: We aim to evaluate the safety of IVIG tapering and withdrawal in patients with SCLS. Methods: We conducted a retrospective multicenter study including all adult patients with monoclonal gammopathy–associated SCLS from the EurêClark registry who received at least 1 course of IVIG. The primary end point was overall survival according to IVIG withdrawal. Results: Fifty-nine patients of mean ± SD age 51 ± 13 years were included. Overall cumulative probabilities of 2-, 5-, 10- and 15-year survival were 100%, 85%, 72%, 44%, respectively. The IVIG was withdrawn at least once in 18 patients (31%; W+ group) and never in 41 patients (69%; W– group). Cumulative probabilities of 10-year survival in W+ versus W– groups were 50% and 83% (log rank test, P = .02), respectively. Relapse rate and the median number of relapses in the W+ versus the W– groups were 72% versus 58% (P = 0.3) and 2.5 (0.3–4) versus 1 (0–2) (P = .03), respectively. The IVIG tapering was not statistically associated with increased person-year incidence of attacks using a mixed linear model. Conclusions: The IVIG withdrawal was associated with increased mortality and higher rate of recurrence in SCLS patients. The IVIG tapering might be cautiously considered in stable SCLS patients

Intravenous Immunoglobulins Improve Survival in Monoclonal Gammopathy-Associated Systemic Capillary-Leak Syndrome

International audienceBackground: Monoclonal gammopathy-associated systemic capillary-leak syndrome, also known as Clarkson disease, is a rare condition characterized by recurrent life-threatening episodes of capillary hyperpermeability in the context of a monoclonal gammopathy. This study was conducted to better describe the clinical characteristics, natural history, and long-term outcome of monoclonal gammopathy-associated systemic capillary-leak syndrome.Methods: We conducted a cohort analysis of all patients included in the European Clarkson disease (EurêClark) registry between January 1997 and March 2016. From diagnosis to last follow-up, studied outcomes (eg, the frequency and severity of attacks, death, and evolution toward multiple myeloma) and the type of preventive treatments administered were monitored every 6 months.Results: Sixty-nine patients (M/F sex ratio 1:1; mean ± SD age at disease onset 52 ± 12 years) were included in the study. All patients had monoclonal gammopathy of immunoglobulin G type, with kappa light chains in 47 (68%). Median (interquartile range) follow-up duration was 5.1 (2.5-9.7) years. Twenty-four patients (35%) died after 3.3 (0.9-8) years. Fifty-seven (86%) patients received at least one preventive treatment, including intravenous immunoglobulins (IVIg) n = 48 (73.8%), theophylline n = 22 (33.8%), terbutaline n = 22 (33.8%), and thalidomide n = 5 (7.7%). In the 65 patients with follow-up, 5- and 10-year survival rates were 78% (n = 35) and 69% (n = 17), respectively. Multivariate analysis found preventive treatment with IVIg (hazard ratio 0.27; 95% confidence interval, 0.10-0.70; P = .007) and terbutaline (hazard ratio 0.35; 95% confidence interval, 0.13-0.96; P = .041) to be independent predictors of mortality.Conclusions: We describe the largest cohort to date of patients with well-defined monoclonal gammopathy-associated systemic capillary-leak syndrome. Preventive treatment with IVIg was the strongest factor associated with survival, suggesting the use of IVIg as the first line in prevention therapy