Background: Hemophagocytic lymphohistiocytosis (HLH) is a severe disorder characterized by excessive secretion of cytokines. Even with the recommended HLH-94/2004 regimen, over 30% of patients remain refractory to frontline therapy or relapse after an initial response, leading to poor clinical outcomes. Ruxolitinib, a JAK1/2 inhibitor targets key cytokines in HLH, has shown promising therapeutic effects. However, there has been little attention given to patients who do not respond to ruxolitinib and whether an escalating dose can provide a resolution.Methods: This study analyzed eight HLH patients who received dose-escalating ruxolitinib who had previously failed to respond to the general dose. The efficacy and safety were mainly analyzed.Results: Overall, four out of eight (50%) patients achieved better remission after dose escalation. Two patients who only showed improvement with the general dose achieved complete remission (CR) after dose escalation, and the other two patients also achieved CR after dose escalation when they did not respond to the general dose. The median time to achieve the best overall response was 18.5 days (IQR 13.25–23.75 days). There was no correlation of treatment outcome with blood count, liver function, LDH, cytokines, ferritin levels, NK cell activity, or the time to initiation of ruxolitinib and maximum dosage. The etiology of HLH (p=0.029) and level of sCD25 (p=0.021) correlated with treatment response to dose-escalating ruxolitinib. The area of sCD25 under the ROC curve was 0.8125 (95% CI 0.5921 to 1.033, p=0.035) when using 10,000 pg/ml as the cut-off value for predicting therapeutic effects. After a median follow-up of 159 days, two patients died, and the estimated 2-month overall survival rate was 75%. Adverse effects possibly related to the dose-escalating of ruxolitinib included two cases of extremity pain and one of aminotransferase increased. No grade 3 or higher adverse events were reported.Conclusion: This is the first comprehensive study on the use of dose-escalating ruxolitinib in HLH. Ruxolitinib at an escalated dose represent a viable and relatively safe solution for managing refractory HLH. The levels of sCD25 (with a cut-off of 10000pg/ml) can serve as an indicator for early consideration of chemotherapy during treatment.

Disseminated adenovirus infection is a complication with a relatively high mortality rate among patients undergoing hematopoietic stem cell transplantation. The low efficacy and poor availability of current treatment options are of major concern. Programmed cell death 1 (PD-1) blockade has been used to treat several chronic viral infections. Herein, we report a case of disseminated adenovirus infection in the early posttransplant period. The patient was diagnosed with diffuse large B-cell lymphoma at first and underwent 8 cycles of chemotherapy, including rituximab. She was subsequently diagnosed with acute myeloid leukemia and received haploidentical transplantation. She was diagnosed with Epstein‒Barr virus (EBV)-positive posttransplant lymphoproliferative disorder (PTLD) 2 months after the transplant, and 3 doses of rituximab were administered. The patient was diagnosed with disseminated adenovirus infection with upper respiratory tract, gastrointestinal tract and blood involved at 3 months after transplantation. She was first treated with a reduction in immunosuppression, cidofovir and ribavirin. Then, the patient received salvage treatment with the PD-1 inhibitor sintilimab (200 mg) after achieving no response to conventional therapy. The adenovirus was cleared 3 weeks later, and concomitant EBV was also cleared. Although the patient developed graft-versus-host disease of the liver after the administration of the PD-1 inhibitor, she was cured with steroid-free therapy. Therefore, PD-1 blockade immunotherapy can be considered a promising treatment option for patients with disseminated adenovirus infection after transplantation, with fully weighing the hazards of infection and the side effects of this therapy.