Ruxolitinib plus standard of care in severe hospitalized adults with severe fever with thrombocytopenia syndrome (SFTS): an exploratory, single-arm trial.

BACKGROUND: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne infectious disease, and its morbidity and mortality are increasing. At present, there is no specific therapy available. An exacerbated IFN-I response and cytokine storm are related to the mortality of patients with SFTS. Ruxolitinib is a Janus kinase (JAK) 1/2 inhibitor that can block proinflammatory cytokines and inhibit the type I IFN pathway. We aimed to explore the use of ruxolitinib plus standard of care for severe SFTS. METHODS: We conducted a prospective, single-arm study of severe SFTS. We recruited participants aged 18 years or older who were admitted to the hospital with laboratory-confirmed severe SFTS and whose clinical score exceeded 8 points within 6 days of symptom onset. Participants received oral ruxolitinib (10 mg twice a day) for up to 10 days. The primary endpoint was 28-day overall survival. The secondary endpoints included the proportion of participants who needed intensive care unit (ICU) admission, total cost, changes in neurologic symptoms and clinical laboratory parameters, and adverse events (AEs) within 28 days. A historical control group (HC group, n = 26) who met the upper criteria for inclusion and hospitalized from April 1, 2021, to September 16, 2022, was selected and 1:1 matched for baseline characteristics by propensity score matching. RESULTS: Between Sep 16, 2022, and Sep 16, 2023, 26 participants were recruited into the ruxolitinib treatment group (RUX group). The 28-day overall mortality was 7.7% in the RUX group and 46.2% in the HC group (P = 0.0017). There was a significantly lower proportion of ICU admissions (15.4% vs 65.4%, p < 0.001) and total hospitalization cost in the RUX group. Substantial improvements in neurologic symptoms, platelet counts, hyperferritinemia, and an absolute decrease in the serum SFTS viral load were observed in all surviving participants. Treatment-related adverse events were developed in 6 patients (23.2%) and worsened in 8 patients (30.8%), and no treatment-related serious adverse events were reported. CONCLUSIONS: Our findings indicate that ruxolitinib has the potential to increase the likelihood of survival as well as reduce the proportion of ICU hospitalization and being tolerated in severe SFTS. Further trials are needed. TRAIL REGISTRATION: ChiCTR2200063759, September 16, 2022.

Recent Advances in the Study of the Immune Escape Mechanism of SFTSV and Its Therapeutic Agents.

Sever fever with thrombocytopenia syndrome (SFTS) is a new infectious disease that has emerged in recent years and is widely distributed, highly contagious, and lethal, with a mortality rate of up to 30%, especially in people with immune system deficiencies and elderly patients. SFTS is an insidious, negative-stranded RNA virus that has a major public health impact worldwide. The development of a vaccine and the hunt for potent therapeutic drugs are crucial to the prevention and treatment of Bunyavirus infection because there is no particular treatment for SFTS. In this respect, investigating the mechanics of SFTS-host cell interactions is crucial for creating antiviral medications. In the present paper, we summarized the mechanism of interaction between SFTS and pattern recognition receptors, endogenous antiviral factors, inflammatory factors, and immune cells. Furthermore, we summarized the current therapeutic drugs used for SFTS treatment, aiming to provide a theoretical basis for the development of targets and drugs against SFTS.

The combination of levodopa with levodopa-metabolizing enzyme inhibitors prevents severe fever with thrombocytopenia syndrome virus infection in vitro more effectively than single levodopa.

Severe fever with thrombocytopenia syndrome is a hemorrhagic fever caused by a tick-borne infection. The causative agent, Dabie bandavirus, is also called the severe fever with thrombocytopenia syndrome virus (SFTSV). Ogawa et al. (2022) reported that levodopa, an antiparkinsonian drug with an o-dihydroxybenzene backbone, which is important for anti-SFTSV activity, inhibited SFTSV infection. Levodopa is metabolized by dopa decarboxylase (DDC) and catechol-O-methyltransferase (COMT) in vivo. We evaluated the anti-SFTSV efficacy of two DDC inhibitors, benserazide hydrochloride and carbidopa, and two COMT inhibitors, entacapone and nitecapone, which also have an o-dihydroxybenzene backbone. Only DDC inhibitors inhibited SFTSV infection with pretreatment of the virus (half-maximal inhibitory concentration [IC50]: 9.0-23.6 µM), whereas all the drugs inhibited SFTSV infection when infected cells were treated (IC50: 21.3-94.2 µM). Levodopa combined with carbidopa and/or entacapone inhibited SFTSV infection in both conditions: pretreatment of the virus (IC50: 2.9-5.8 µM) and treatment of infected cells (IC50: 10.7-15.4 µM). The IC50 of levodopa in the above-mentioned study for pretreatment of the virus and treatment of infected cells were 4.5 and 21.4 µM, respectively. This suggests that a synergistic effect was observed, especially for treatment of infected cells, although the effect is unclear for pretreatment of the virus. This study demonstrates the anti-SFTSV efficacy of levodopa-metabolizing enzyme inhibitors in vitro. These drugs may increase the time for which the levodopa concentration is maintained in vivo. The combination of levodopa and levodopa-metabolizing enzyme inhibitors might be a candidate for drug repurposing.

CD8+ T cells mediate antiviral response in severe fever with thrombocytopenia syndrome.

Severe fever with thrombocytopenia syndrome (SFTS), which is caused by a novel Bunyavirus, has gradually become a threatening infectious disease in rural areas of Asia. Studies have identified a severe cytokine storm and impaired humoral immune response in SFTS. However, the cellular immune response to SFTS virus (SFTSV) infection remains largely unknown. Here we report that SFTS patients had a cytokine storm accompanied by high levels of chemokines. CD8+ T cells in peripheral blood mononuclear cells of SFTS patients exhibited a more activated phenotype and enhanced the antiviral responses. They increased the expression of CD69 and CD25, secreted a higher level of IFN-γ and granzyme, and had a stronger proliferative ability than in healthy controls. In convalescent SFTS patients, the expression of CD69 and CD25 on CD8+ T cells was reduced. In addition, we found the ratio and cellularity of CD14+ CD16+ intermediate monocytes were increased in peripheral blood of SFTS patients. Both the expression of C-X-C motif chemokine ligand 10 (CXCL10) on CD14+ CD16+ intermediate monocytes and the expression of C-X-C motif chemokine receptor 3 (CXCR3) on CD8+ T cells increased dramatically in SFTS patients. Our studies reveal a potential pathway that CD8+ T cells rapidly activate and are mostly recruited by intermediate monocytes through CXCL10 in SFTSV infection. Our results may be of clinical relevance for further treatment and discharge instructions in SFTSV infections.

Amodiaquine derivatives as inhibitors of severe fever with thrombocytopenia syndrome virus (SFTSV) replication.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne viral infection caused by a bandavirus in the family of Phenuiviridae, commonly known as SFTS virus (SFTSV). We have previously isolated SFTSV from blood samples of SFTS patients and established an antiviral assay system to identify selective inhibitors of SFTSV in vitro. Using the assay system, the antimalarial agent amodiaquine was identified as a selective inhibitor of SFTSV replication. However, due to its insufficient antiviral activity, 98 amodiaquine derivatives were newly synthesized and examined for their anti-SFTSV activity. Among the derivatives, some compounds showed selective inhibitory effect on SFTSV replication in vitro. The 50% effective concentration (EC50) and cytotoxic concentration (CC50) of the most active compound (C-90) were 2.6 ± 0.6 and >50 µM, respectively. This EC50 value was comparable to or slightly better than that of favipiravir (4.1 ± 0.6 µM). On the other hand, pharmacokinetic studies in vivo revealed that C-90 was poor in its oral bioavailability in mice. Therefore, we further designed and synthesized derivatives and obtained 2 compounds with selective anti-SFTSV activity in vitro and improved pharmacokinetics in vivo.

Potential efficacy of existing drug molecules against severe fever with thrombocytopenia syndrome virus: an in silico study.

Severe fever with thrombocytopenia syndrome (SFTS) is a zoonotic disease caused by the SFTS virus (SFTSV). SFTS can be considered a life-threatening notifiable infectious disease. The unavailability of specific therapeutics encourages the investigation of potential efficacy of existing drugs against this infection. Drug repurposing was done by performing  virtual screening of already established drug molecules followed by 100 ns molecular dynamics simulations and molecular mechanics Poisson-Boltzmann surface area-based binding-energy calculation by targeting the SFTS L protein. On the basis of binding energy and protein-ligand interactions, top 10 promising hits were identified, showing stable binding with SFTS L protein. Further 100 ns atomistic MD simulation refined the hits from top 10 to top 4 with docking-based binding energy lesser than -8.0 kcal/mol toward the SFTS L protein and engaged in π-π interactions with pivotal amino acid residues. Various parameters and binding affinity of top 4 ligands towards L protein was computed. Ligand zaltoprofen exhibited best binding energy -220.095 kJ/mol. The present work is the first in silico study to assess bromfenac, cinchophen, elliptinium, and zaltoprofen; four promising hits against SFTS. Nonetheless, further proper biological evaluation is necessary to determine their efficacy against SFTS.

In Silico Structure-Based Design of Antiviral Peptides Targeting the Severe Fever with Thrombocytopenia Syndrome Virus Glycoprotein Gn.

Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne bunyavirus in Asia that causes severe disease. Despite its clinical importance, treatment options for SFTSV infection remains limited. The SFTSV glycoprotein Gn plays a major role in mediating virus entry into host cells and is therefore a potential antiviral target. In this study, we employed an in silico structure-based strategy to design novel cyclic antiviral peptides that target the SFTSV glycoprotein Gn. Among the cyclic peptides, HKU-P1 potently neutralizes the SFTSV virion. Combinatorial treatment with HKU-P1 and the broad-spectrum viral RNA-dependent RNA polymerase inhibitor favipiravir exhibited synergistic antiviral effects in vitro. The in silico peptide design platform in this study may facilitate the generation of novel antiviral peptides for other emerging viruses.

Clinical efficacy and safety evaluation of favipiravir in treating patients with severe fever with thrombocytopenia syndrome.

BACKGROUND: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease with high mortality, however with no effective therapy available. METHODS: The effect of favipiravir (FPV) in treating SFTS was evaluated by an integrated analysis on data collected from a single-arm study (n=428), a surveillance study (n=2350) and published data from a randomized controlled trial study (n=145). A 1:1 propensity score matching was performed to include 780 patients: 390 received FPV and 390 received supportive therapy only. Case fatality rates (CFRs), clinical progress, and adverse effects were compared. FINDINGS: FPV treatment had significantly reduced CFR from 20.0% to 9.0% (odds ratio 0.38, 95% confidence interval 0.23-0.65), however showing heterogeneity when patients were grouped by age, onset-to-admission interval, initial viral load and therapy duration. The effect of FPV was significant only among patients aged ≤70 years, with onset-to-admission interval ≤5 days, therapy duration ≥5 days or baseline viral load ≤1 × 106 copies/mL. Age-stratified analysis revealed no benefit in the aging group >70 years, regardless of their sex, onset-to-admission interval, therapy duration or baseline viral load. However, for both ≤60 and 60-70 years groups, therapy duration and baseline viral load differentially affected FPV therapy efficiency. Hyperuricemia and thrombocytopenia, as the major adverse response of FPV usage, were observed in >70 years patients. INTERPRETATION: FPV was safe in treating SFTS patients but showed no benefit for those aged >70 years. Instant FPV therapy could highly benefit SFTS patients aged 60-70 years. FUNDING: China Natural Science Foundation (No. 81825019, 82073617 and 81722041) and China Mega-project for Infectious Diseases (2018ZX10713002 and 2015ZX09102022).

A longitudinal sampling study of transcriptomic and epigenetic profiles in patients with thrombocytopenia syndrome.

Severe fever with thrombocytopenia syndrome (SFTS) is a novel tick-borne infectious disease caused by a new type of SFTS virus (SFTSV). Here, a longitudinal sampling study is conducted to explore the differences in transcript levels after SFTSV infection, and to characterize the transcriptomic and epigenetic profiles of hospitalized patients. The results reveal significant changes in the mRNA expression of certain genes from onset to recovery. Moreover, m6A-seq reveals that certain genes related with immune regulation may be regulated by m6A. Besides the routine tests such as platelet counts, serum ALT and AST levels testing, distinct changes in myocardial enzymes, coagulation function, and inflammation are well correlated with the clinical data and sequencing data, suggesting that clinical practitioners should monitor the above indicators to track disease progression and guide personalized treatment. In this study, the transcript changes and RNA modification may lend a fresh perspective to our understanding of the SFTSV and play a significant role in the discovery of drugs for effective treatment of this disease.

Peptides derived from viral glycoprotein Gc Inhibit infection of severe fever with thrombocytopenia syndrome virus.

Severe fever with thrombocytopenia syndrome (SFTS) is an acute infectious disease caused by a novel phlebovirus (SFTSV), characterized by fever, thrombocytopenia and leukocytopenia which lead to multiple organ failure with high mortality in severe cases. The SFTSV has spread rapidly in recent years and posed a serious threat to public health in endemic areas. However, specific antiviral therapeutics for SFTSV infection are rare. In this study, we demonstrated that two peptides, SGc1 and SGc8, derived from a hydrophobic region of the SFTSV glycoprotein Gc, could potently inhibit SFTSV replication in a dose-dependent manner without apparent cytotoxicity in various cell lines and with low immunogenicity and good stability. The IC50 (50% inhibition concentration) values for both peptides to inhibit 2 MOI of SFTSV infection were below 10 µM in L02, Vero and BHK21 cells. Mechanistically, SGc1 and SGc8 mainly inhibited viral entry at the early stage of the viral infection. Inhibition of SFTSV replication was specific by both peptides because no inhibitory effect was shown against other viruses including Zika virus and Enterovirus A71. Taken together, our results suggested that viral glycoprotein-derived SGc1 and SGc8 peptides have antiviral potential and warrant further assessment as an SFTSV-specific therapeutic.

Clinical effect and antiviral mechanism of T-705 in treating severe fever with thrombocytopenia syndrome.

Severe fever with thrombocytopenia syndrome (SFTS) virus (SFTSV) is an emerging tick-borne virus with high fatality and an expanding endemic. Currently, effective anti-SFTSV intervention remains unavailable. Favipiravir (T-705) was recently reported to show in vitro and in animal model antiviral efficacy against SFTSV. Here, we conducted a single-blind, randomized controlled trial to assess the efficacy and safety of T-705 in treating SFTS (Chinese Clinical Trial Registry website, number ChiCTR1900023350). From May to August 2018, laboratory-confirmed SFTS patients were recruited from a designated hospital and randomly assigned to receive oral T-705 in combination with supportive care or supportive care only. Fatal outcome occurred in 9.5% (7/74) of T-705 treated patients and 18.3% (13/71) of controls (odds ratio, 0.466, 95% CI, 0.174-1.247). Cox regression showed a significant reduction in case fatality rate (CFR) with an adjusted hazard ratio of 0.366 (95% CI, 0.142-0.944). Among the low-viral load subgroup (RT-PCR cycle threshold ≥26), T-705 treatment significantly reduced CFR from 11.5 to 1.6% (P = 0.029), while no between-arm difference was observed in the high-viral load subgroup (RT-PCR cycle threshold <26). The T-705-treated group showed shorter viral clearance, lower incidence of hemorrhagic signs, and faster recovery of laboratory abnormities compared with the controls. The in vitro and animal experiments demonstrated that the antiviral efficacies of T-705 were proportionally induced by SFTSV mutation rates, particularly from two transition mutation types. The mutation analyses on T-705-treated serum samples disclosed a partially consistent mutagenesis pattern as those of the in vitro or animal experiments in reducing the SFTSV viral loads, further supporting the anti-SFTSV effect of T-705, especially for the low-viral loads.

Corticosteroids May Have Negative Effects on the Management of Patients with Severe Fever with Thrombocytopenia Syndrome: A Case-Control Study.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging viral hemorrhagic fever in China, Korea, and Japan. To date, no standardized treatment protocol for SFTS has been established. Corticosteroids (CS) may be administered to patients with SFTS and hemophagocytic syndrome, but its effectiveness and safety are still debatable. We conducted a retrospective case series review at four medical facilities in Miyazaki, Japan. Based on the medical records, clinical data, including the patients background, symptoms, physical findings, laboratory data at initial presentation, treatment, and outcome, were compared between the CS-treated and the non-CS-treated group. A total of 47 patients with confirmed SFTS in each hospital were enrolled in this study; there were 14 fatal cases and 33 nonfatal cases. The case fatality ratio was 29.8%. After adjusting patients' background by propensity score matching, the case fatality ratio was higher (p = 0.04) and complications of secondary infections, including invasive pulmonary aspergillosis, tended to be more frequent (p = 0.07) in the CS-treated group than in the non-CS-treated group. These data suggested that administration of CS to patients with SFTS should be carefully considered.

A multicenter non-randomized, uncontrolled single arm trial for evaluation of the efficacy and the safety of the treatment with favipiravir for patients with severe fever with thrombocytopenia syndrome.

Severe fever with thrombocytopenia syndrome (SFTS) is a bunyavirus infection with high mortality. Favipiravir has shown effectiveness in preventing and treating SFTS virus (SFTSV) infection in animal models. A multicenter non-randomized, uncontrolled single arm trial was conducted to collect data on the safety and the effectiveness of favipiravir in treatment of SFTS patients. All participants received favipiravir orally (first-day loading dose of 1800 mg twice a day followed by 800 mg twice a day for 7-14 days in total). SFTSV RT-PCR and biochemistry tests were performed at designated time points. Outcomes were 28-day mortality, clinical improvement, viral load evolution, and adverse events (AEs). Twenty-six patients were enrolled, of whom 23 were analyzed. Four of these 23 patients died of multi-organ failure within one week (28-day mortality rate: 17.3%). Oral favipiravir was well tolerated in the surviving patients. AEs (abnormal hepatic function and insomnia) occurred in about 20% of the patients. Clinical symptoms improved in all patients who survived from a median of day 2 to day10. SFTSV RNA levels in the patients who died were significantly higher than those in the survivors (p = 0.0029). No viral genomes were detectable in the surviving patients a median of 8 days after favipiravir administration. The 28-day mortality rate in this study was lower than those of the previous studies in Japan. The high frequency of hepatic dysfunction as an AE was observed. However, it was unclear whether this was merely a side effect of favipiravir, because liver disorders are commonly seen in SFTS patients. The results of this trial support the effectiveness of favipiravir for patients with SFTS.

Severe fever with thrombocytopenia syndrome in Hefei: Clinical features, risk factors, and ribavirin therapeutic efficacy.

OBJECTIVES: This study described the clinical features, risk factors, factors affecting the outcome of this disease, and ribavirin therapeutic efficacy for severe fever with thrombocytopenia syndrome (SFTS) patients in Hefei. METHODS: Between April 2020 and July 2020, 62 cases admitted to the First Affiliated Hospital of Anhui Medical University were included in this study. Serum samples were collected from all patients, after which diagnosis was made via reverse transcription-polymerase chain reaction and via the use of a colloidal gold immunochromatography assay approach. RESULTS: In multivariate analysis, the following factors were determined as risk factors for SFTS: Being a farmer (odds ratio [OR], 3.033), working in areas with weeds and shrubs (OR, 2.807), and being bitten by a tick (OR, 6.64). The rates of confusion, neck stiffness, viral encephalopathy, and the presence of liver damage were higher in the patients who died than that in the surviving ones. Additionally, the median of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, creatine phosphokinase, activated partial thromboplastin time, D-dimer, fibrinogen degradation products, creatinine, and urea was also higher in the patients who died. One of the 15 patients treated with ribavirin in the early stage could not survive (6.7%), whereas 11 of the 35 patients treated with ribavirin in the late stage could not survive (31.4%); this difference was statistically significant. However, there was no significant difference in mortality between the untreated group and the other two groups (i.e., patients who started antiviral treatment <5 days from the onset and those who started antiviral treatment ≥5 days from the onset). Moreover, there was no positive effect determined on clinical or laboratory parameters in SFTS patients treated with ribavirin. Also, it was observed that leukocyte levels and platelet levels took longer to return to normal. CONCLUSIONS: In Hefei, clinical features, prognostic factors, and risk factors associated with SFTS are similar to those in other areas. Patients who were given ribavirin did not have better survival rates than patients who were not given ribavirin.