Spleen tyrosine kinase (SYK) is an important regulatory molecule of signal transduction pathways involved in the pathogenesis of autoimmune diseases such as immune thrombocytopenia (ITP), and the SYK-signaling pathway has emerged as a potential target for the treatment of numerous diseases. The aim of this narrative review is to summarize the biological properties of SYK and its involvement in disease pathways, provide an update on SYK inhibitors in the treatment of ITP, and consider other potential applications. Fostamatinib, the only licensed SYK inhibitor to date, produces clinical response in ITP patients, including those who are refractory to other treatments. It appears to reduce the risk of thrombotic events and may therefore be a drug to consider for patients with an increased thrombotic risk. Encouraging results have also been obtained in the treatment of warm autoimmune hemolytic anemia. Several other SYK inhibitors have entered clinical trials for a range of indications, reflecting the ability of these drugs to affect multiple signaling pathways. SYK inhibitors have the potential to target several aspects of COVID-19 pathogenesis including thrombosis, without affecting normal hemostasis, and data from the first study of fostamatinib in COVID-19 are encouraging. It is hoped that ongoing trials in autoimmune indications other than ITP, as well as in hematological malignancies and other disorders, confirm the promise of SYK inhibitors.
The impact of COVID-19 infection on pregnant women remains relatively unknown but the physiological changes of pregnancy and hypercoagulability of COVID-19 may further increase thrombotic risk. In this retrospective multicentre observational study, we report clinical characteristics and outcomes in 36 pregnant women requiring hospitalisation for COVID-19 compared to a propensity-matched cohort of non-pregnant women. Pregnant women had a lower haemoglobin and higher lymphocyte counts but no differences in other haematological or biochemical parameters on admission compared to non-pregnant women. There was no significant difference in the duration of hospitalisation; median two days (1-77) for pregnant versus eight days (1-49) for non-pregnant women. A higher proportion of nonpregnant women required mechanical ventilation [11/36 (31%) vs 3/36 (8%), P = 0Á03] and received thromboprophylaxis with low-molecular-weight heparin (LMWH) within 24 h of admission [25/36 (69%) vs 15 /36(42%), P = 0Á03] compared to pregnant women. One pregnant woman required extracorporeal membrane oxygenation. The rate of thrombosis was similar in both groups (one in each group). No women developed major bleeding or died. Data suggest that although non-pregnant women had a severe clinical course, overall outcomes were not different between women with or without pregnancy. The use of thromboprophylaxis was inconsistent, demonstrating a need for establishing evidence-based guidance for COVID-19 during pregnancy.
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