Ruxolitinib in Alleviating the Cytokine Storm of Hemophagocytic Lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) is a rare and life-threatening syndrome classified into primary HLH and secondary HLH. Secondary HLH is always caused by autoimmune disease, infections, or cancer. The first-line therapy for secondary HLH is the HLH 2004 protocol, including dexamethasone, etoposide, and supportive therapy. However, up to 30% of patients, especially pediatric patients, remain unresponsive to first-line treatment, and the mortality rate reaches 50% in children with HLH. Furthermore, some children who have special conditions, such as an active virus infection, are not suitable for immunosuppressants treatment. Recently, several HLH-promoting cytokines have been identified, including interferon-γ, interleukin-2, and interleukin-6. Janus kinase 1 and 2 control the signaling of many cytokines, notably interferon-γ, interleukin-2, and interleukin-6. Janus kinase 1 and 2 inhibitors, such as ruxolitinib, have been successfully used to treat HLH in mice. Here, we report that a boy, diagnosed with HLH and high titer of hepatitis B virus-DNA copies, improved quickly, and the cytokine storm of HLH was alleviated after receiving ruxolitinib. Five days after ruxolitinib treatment, entecavir was introduced and serum titer results of hepatitis B virus-DNA returned negative. With 3 months of ruxolitinib treatment and following-up 1 year, the boy's situation maintained sustained remission. In this study, it is suggested that ruxolitinib might be a first-line drug, which could alleviate the cytokine storm of HLH. This treatment may be ushering in the age of glucocorticosteroid-free HLH treatment, which is particularly meaningful for children because it avoids the side effects of glucocorticosteroid.

Jianguo L ，Zhixuan Z ，Rong L ，Xiaodong S ... -  《-》

Ruxolitinib as adjunctive therapy for secondary hemophagocytic lymphohistiocytosis: A case series.

Hemophagocytic lymphohistiocytosis (HLH) is a cytokine storm syndrome associated with mortality rates of up to 88%. Standard therapy with high-dose glucocorticoids and etoposide used in adults is extrapolated from pediatric trials, with significant toxicity in older patients and those with poor performance status. The JAK1/2 inhibitor ruxolitinib has recently gained attention as a treatment option for HLH due to its broad cytokine-modulating abilities and safety profile. Herein we report our center's experience using ruxolitinib in the treatment of adult-onset secondary HLH. We report four patients with profound secondary HLH provoked by diverse triggers, including invasive pulmonary aspergillosis on background systemic lupus erythematosus, disseminated tuberculosis, and T-cell lymphoma treated with ruxolitinib as monotherapy or combination therapy in upfront and salvage settings. All four patients had rapid, sustained improvement in clinical status, inflammatory markers, and hematological cell counts followed by durable remission. Three patients developed manageable infectious complications postruxolitinib. This series demonstrates the effective use of JAK inhibition with ruxolitinib to control pathological immune activation in critically ill patients with secondary HLH and otherwise limited therapeutic options. JAK inhibition is also an area of urgent investigation for the treatment of cytokine storm associated with COVID-19.

Hansen S ，Alduaij W ，Biggs CM ，Belga S ，Luecke K ，Merkeley H ，Chen LYC ... -  《-》

JAK/STAT pathway inhibition sensitizes CD8 T cells to dexamethasone-induced apoptosis in hyperinflammation.

Cytokine storm syndromes (CSS) are severe hyperinflammatory conditions characterized by excessive immune system activation leading to organ damage and death. Hemophagocytic lymphohistiocytosis (HLH), a disease often associated with inherited defects in cell-mediated cytotoxicity, serves as a prototypical CSS for which the 5-year survival is only 60%. Frontline therapy for HLH consists of the glucocorticoid dexamethasone (DEX) and the chemotherapeutic agent etoposide. Many patients, however, are refractory to this treatment or relapse after an initial response. Notably, many cytokines that are elevated in HLH activate the JAK/STAT pathway, and the JAK1/2 inhibitor ruxolitinib (RUX) has shown efficacy in murine HLH models and humans with refractory disease. We recently reported that cytokine-induced JAK/STAT signaling mediates DEX resistance in T cell acute lymphoblastic leukemia (T-ALL) cells, and that this could be effectively reversed by RUX. On the basis of these findings, we hypothesized that cytokine-mediated JAK/STAT signaling might similarly contribute to DEX resistance in HLH, and that RUX treatment would overcome this phenomenon. Using ex vivo assays, a murine model of HLH, and primary patient samples, we demonstrate that the hypercytokinemia of HLH reduces the apoptotic potential of CD8 T cells leading to relative DEX resistance. Upon exposure to RUX, this apoptotic potential is restored, thereby sensitizing CD8 T cells to DEX-induced apoptosis in vitro and significantly reducing tissue immunopathology and HLH disease manifestations in vivo. Our findings provide rationale for combining DEX and RUX to enhance the lymphotoxic effects of DEX and thus improve the outcomes for patients with HLH and related CSS.

Meyer LK ，Verbist KC ，Albeituni S ，Scull BP ，Bassett RC ，Stroh AN ，Tillman H ，Allen CE ，Hermiston ML ，Nichols KE ... -  《-》

Use of the JAK Inhibitor Ruxolitinib in the Treatment of Hemophagocytic Lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) is a rare hyperinflammatory syndrome driven by overactive T cells and macrophages that abundantly secrete numerous pro-inflammatory cytokines, including interferon (IFN)-gamma, interleukin (IL)-1-beta, IL-2, IL-6, IL-10, IL-18, and tumor necrosis factor (TNF). The release of these and other cytokines underlies many of the clinical and pathologic manifestations of HLH, which if left untreated, can lead to multi-organ failure and death. The advent of etoposide-based regimens, such as the Histiocyte Society HLH-94 and HLH-2004 protocols, has substantially decreased the mortality associated with HLH. Nevertheless, the 5-year survival remains low at ~60%. To improve upon these results, studies have focused on the use of novel cytokine-directed therapies to dampen inflammation in HLH. Among the agents being tested is ruxolitinib, a potent inhibitor of the Janus Kinase (JAK) and Signal Transducer and Activation of Transcription (STAT) pathway, which functions downstream of many HLH-associated cytokines. Here, we review the basic biology of HLH, including the role of cytokines in disease pathogenesis, and discuss the use of ruxolitinib in the treatment of HLH.

Keenan C ，Nichols KE ，Albeituni S 《Frontiers in Immunology》

Ruxolitinib-loaded cytokine nanosponge alleviated the cytokine storm and dampened macrophage overactivation for the treatment of hemophagocytic lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening clinical syndrome characterized by a positive feedback loop between cytokine storm and macrophages and lymphocytes overactivation, which could serve as a valid therapeutic target for HLH treatment. In this study, the clinically extensively used JAK1/2 inhibitor ruxolitinib was encapsulated into macrophage membrane-coated nanoparticles (M@NP-R) with high drug-loading efficiency for targeted HLH treatment. In vitro and in vivo studies demonstrated that M@NP-R not only efficiently adsorbed extracellular proinflammation cytokines, like IFN-γ and IL-6 to alleviate the cytokine storm, but also effectively dampened macrophage activation and proliferation by intracellular JAK/STAT signaling pathway inhibition. M@NP-R treatment significantly ameliorated the clinical and laboratory manifestations of HLH in mouse models, including trilineage cytopenia, hypercytokinemia, organomegaly, hepatorenal dysfunction, and tissue inflammation. Importantly, M@NP-R significantly enhanced the survival of the lethal HLH mice. Altogether, M@NP-R successfully blocked the positive feedback loop between the cytokine storm and macrophage overactivation by depleting extracellular inflammatory cytokines and inhibiting the intracellular JAK/STAT signaling pathway, both of which worked synergistically in HLH treatment. As ruxolitinib has already been extensively used in clinics with favorable safety, and M@NP is biodegradable and highly biocompatible, M@NP-R has good prospects for clinical translation.

Wang H ，Wang Y ，Liu H ，Li X ，Sun C ，Pang Z ，Zhang B ，Hu Y ... -  《-》