A life‐threatening ruxolitinib discontinuation syndrome
Authors: Giacomo Coltro, Francesco Mannelli, Paola Guglielmelli, Annalisa Pacilli, Alberto Bosi, Alessandro Maria Vannucchi
Journal: American Journal of Hematology (2017)

A 56-year-old woman with a history of essential thrombocythemia currently treated with ruxolitinib presented to the clinic for a routine visit in October 2016. She referred unintentional weight loss of about 5 kg in the last 3 months, asthenia, and osteoarticular pain. She denied fever, cough, diarrhea, shortness of breath, constitutional symptoms, or hemorrhage. Essential thrombocythemia (ET), one of the classic chronic myeloproliferative neoplasms together with polycythemia vera (PV) and primary myelofibrosis (MF),1 is an overall indolent disease characterized by persistent thrombocytosis because of abnormal megakaryocytes' proliferation; the latter is sustained by autonomous activation of the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway induced by mutations in JAK2 (V617F), myeloproliferative leukemia virus oncogene (MPL) and calreticulin (CALR). Increased risk of arterial and venous thrombosis and hemorrhage are the main causes of morbidity and mortality in ET; treatment is thereby mainly addressed to reduce the risk of cardiovascular events, and is delivered based on risk stratification criteria.2, 3 Although overall survival in ET is similar to reference population, transformation to post-ET MF (PET-MF) and acute myeloid leukemia (AML) occur in 5-8% and 1-3% of cases, respectively, and are associated with shortening of survival.4 Ruxolitinib, an oral adenosine triphosphate (ATP) mimetic inhibitor of JAK1 and 2 that has received approval for the treatment of patients with MF and PV,5-8 is under investigation in ET in a phase I/II trial. The trial also included patients with PV, that have been already reported.9 The symptomatology referred by the patient was rather unspecific but raised concerns since she had been very well doing in the last years after beginning treatment with ruxolitinib. Her asthenia could be ascribed to ruxolitinib-related anemia, one of the most frequent adverse events of ruxolitinib. Conversely, the remarkable weight loss could be hardly referred to the experimental drug, which eventually causes weight gain; rather, it might be more consistent with progression to PET-MF or, less commonly, to post-ET AML. Of course, other nonhematologic causes had to be taken into an account, including endocrine disorders, infectious and inflammatory states, solid tumors, to name a few. The patient had been diagnosed with ET in another institution 8 years before, following the discovery of extensive thrombocytosis (in excess of 2 millions) and referral of microvascular symptoms. She was initially treated with low-dose aspirin and hydroxycarbamide, which was stopped soon because of hydroxyurea-related fever even at low drug dosage (500 mg daily). She was therefore enrolled in a phase II trial of ruxolitinib in advanced PV and ET in December 2008. At study entry, her white blood cell (WBC) count was 13.8 × 109/L, hemoglobin 138 g/L, platelet count was 2012 × 109/L. Bone marrow (BM) biopsy documented normal cellularity with unilineage hyperplasia of megakaryocytes and absent reticulin fibrosis. A JAK2V617F mutation was documented, variant allele frequency (VAF) was 39%. Physical examination and an abdominal scan excluded splenomegaly. She referred debilitating symptoms including erythromelalgia, paresthesia, scotomas, headache, osteoarticular pain, and occasionally aquagenic pruritus, all refractory to aspirin. Treatment with ruxolitinib was started at 25 mg twice daily, then it was increased to 75 mg daily, the maximum dosage allowed per protocol, because of persistent thrombocytosis. Following dosage increase, the patient referred rapid relief of constitutional symptoms and the platelet count stabilized at 800-900 × 109/L. In April 2014, 65 months while on treatment, the JAK2V617F mutation resulted undetectable despite persistent mild thrombocytosis and unchanged features at a BM re-evaluation, as reported.10 Since April 2015, blood counts progressively decreased and the dosage of ruxolitinib was gradually reduced to 10 mg twice daily, maintaining optimal levels of hemoglobin, WBC and platelet count. Ruxolitinib was well tolerated without significant adverse events, except for some low-grade episodes of superior airway infection successfully treated with oral antimicrobial therapy. On physical examination, the patient presented overall well and was afebrile. There were no palpable lymph nodes, enlarged liver or spleen. Complete blood count revealed mild anemia (hemoglobin 108 g/L), normal platelet count (187 × 109/L), and leukocytosis (WBC 18.2 × 109/L) with a differential count reporting 29% myeloid blasts. Lactate dehydrogenase (LDH) was 393 U/L. A peripheral blood smear and a BM aspirate (Figure 1) confirmed the diagnosis of AML. Flow cytometric analysis of bone marrow aspirate revealed a population of myeloid blast cells with immature features (CD45+, SSClow, CD34+, CD15-/+, CD13++, CD117+, HLA-DR+, CD33-/+, CD10-/+, CD123+, CD1c-, CD5-, CD7-/+, MPO-/+). According to study protocol, the patient was taken off the study treatment. Therefore, a dose tapering scheme was instituted with ruxolitinib to be reduced to 5 mg twice daily for one week and 5 mg once daily for the next week. Peripheral blood smear performed at the diagnosis of post-essential thrombocythemia acute myelogenous leukemia, showing myeloblasts of medium size with irregular nuclei and slightly basophilic cytoplasm containing no granules; some of the cells form pseudopodia-like projections (Wright-Giemsa, 50× original magnification) (panel A). Bone marrow aspirate revealed markedly increase cellularity (20× original magnification) (panel B). A large, mature, hyperlobated megakaryocyte typical of ET is still visible, erythroid lineage is dysplastic (50× original magnification) (panel C). The marrow was infiltrated with blasts that at high-power view (100× original magnification) showed cell pleomorphism and plasmacytoid features in some (panel D). Both progression to post-ET MF and AML mandated study treatment discontinuation. Therefore, although the patients were taking low dose of ruxolitinib (10 mg twice daily), we decided to slowly taper the drug, with the aim to minimize the risk of developing cytokine-rebound phenomena. Unexpectedly, patient's conditions rapidly worsened and 48 hours after the start of ruxolitinib tapering program she presented to the emergency department referring high fever, cough and mild diarrhea without abdominal pain. On physical examination she was alert and oriented, the temperature was 39.5°C, heart rate 90 beats/min, and blood pressure 115/65 mmHg. She had tachypnea and dyspnea, oxygen saturation was 94% while breathing in ambient air. The cardiac and abdomen examinations were normal. Her lungs were clear without pathological breath sounds. The WBC count was 19.6 × 109/L; differential revealed 7% neutrophils, 17% lymphocytes, 8% monocytes, and 68% blasts. The hemoglobin level was 99 g/L, platelets count 92 × 109/L, LDH 519 U/L. Prothrombin time and serum creatinine levels were slightly elevated while other coagulation parameters, serum electrolytes, procalcitonin level, and liver- and pancreatic-function tests were within normal range. Arterial blood gas analysis performed in ambient air revealed a pH of 7.48, PaO2 56 mmHg, PaCO2 29.5 mmHg, and lactate level 1.3 mmol/L. A chest X-ray showed accentuated lung markings without pulmonary consolidation (Figure 2A). In the suspicion of an AML-related infectious disease, the patient was hospitalized and ruxolitinib was stopped. Empiric therapy with broad spectrum antibiotics was started along with oxygen and fluid support. Chest X ray performed on the day of presentation at the emergency department (panel A). Chest CT scan performed 2 days later, at the onset of the acute respiratory distress syndrome, revealed the presence of diffuse and confluent bilateral ground glass opacities and pseudonodular consolidations together with pleural and pericardial effusion (panel B,C) Patient's clinical presentation and laboratory findings were mostly consistent with AML-related infectious complication because of neutropenia. Furthermore, the patient presented with tachypnea and dyspnea and arterial blood gas analysis revealed moderate hypoxemia. These findings prompted administration of broad spectrum antibiotics along with supportive measurements, while continuing diagnostic work-up. Within 36 hours from admission, the patient developed septic-like features with temperature 39.6°C, hypotension, tachycardia, tachypnea, and worsening hypoxemia with an oxygen saturation of 86% while on oxygen via high-flow nasal cannula. Her clinical status dramatically deteriorated and the patient required noninvasive ventilation. Broad spectrum antibiotic therapy was empirically enhanced and intravenous methylprednisolone was administered. Despite initial clinical stabilization, patient's hypoxemia abruptly worsened and she developed an acute respiratory distress syndrome (ARDS) that required recovery in the intensive care unit (ICU). She was immediately intubated and mechanically ventilated. A chest computered tomography (CT) scan revealed the presence of diffuse and confluent bilateral ground glass opacities and pseudonodular consolidations associated with pleural and pericardial effusion (Figure 2B,C). The onset of progressive respiratory failure along with CT scan findings, as well as the rapid worsening of patient's condition despite antibiotic treatment, might still be in favor of the initial diagnostic suspicion of AML-related infectious pneumonia. However, other common causes of acute respiratory failure, such as heart failure, noncardiogenic pulmonary edema and acute massive pulmonary embolism were evaluated. Repeated blood cultures and urine cultures resulted negative and no agents potentially causative of the pneumonia could be identified: microscopic examination, cultures and polymerase chain reaction on bronchoalveolar lavage were all negative for pathogenic and opportunistic bacteria, molds, yields, and respiratory viruses. A transthoracic echocardiogram excluded heart failure and a CT angiography excluded massive pulmonary embolism. Creatinine level, liver-function tests, amylase, and lipase were in normal range, while blast count further increased (WBC 61 × 109/L, blasts 81%), LDH was 1178 U/L, anemia worsened requiring transfusion of packed red blood cells, and thrombocytopenia developed. A repeated chest CT scan revealed expansion of bilateral ground glass opacities and consolidations along with increased pleural effusion (Figure 3A,B). An abdomen CT scan demonstrated diffuse peritoneal effusion and a peripheral splenic infarction with normal spleen volume (Figure 4). Owing that no infectious agents could be demonstrated, and based on the results of radiological assessment, the patient's respiratory failure was considered possibly related to ruxolitinib withdrawal rather than to infectious pneumonia. Therefore, a working diagnosis of ruxolitinib discontinuation-related ARDS was made. Chest CT scan performed during intensive care unit recovery showing progression of bilateral ground glass opacities and consolidations along with worsening of pleural and pericardial effusion (panel A,B). A marked reduction of ground glass infiltrates in both lungs, as well as resolution of pleural and pericardial effusion, was demonstrated in a chest CT scan performed 7 days after reintroduction of ruxolitinib 10 mg twice daily (panel C,D) Abdomen CT scan performed 4 days after the onset of the acute respiratory distress syndrome showed normal splenic volume and the presence of splenic infarction in the upper pole (arrow). [Color figure can be viewed at wileyonlinelibrary.com] Although a negative infectious work-up, as well as the inefficacy of promptly instituted antimicrobial treatment, cannot definitely rule out the possibility of an infectious complication in a neutropenic patient with AML, we reasoned that an underlying infection could hardly explain the rapid patient deterioration. Therefore, we considered the possibility of ruxolitinib discontinuation-related adverse event. Anecdotal descriptions of sometimes severe adverse events following ruxolitinib abrupt discontinuation were reported and attributed to a rebound cytokine storm; this patient' presentation showed some similarities with previously published case reports. Antibiotics and mechanical ventilation were continued and ruxolitinib therapy was re-introduced at the dose of 10 mg twice daily while continuing systemic steroids. The patient experienced progressive, dramatic improvement in the following 48 hours, became rapidly afebrile and could be successfully extubated 9 days later. She was then transferred to the hematology department where ruxolitinib and steroid therapy was progressively tapered without complications until definitive stop 37 days after ruxolitinib had been reintroduced. A repeated chest CT scan demonstrated marked reduction of ground glass infiltrates in both lungs and resolution of pleural effusion (Figure 3C,D). At that time, the patient started induction with cytarabine and idarubicin. However, she failed to obtain remission and was immediately transplanted from her sibling donor; 120 days after transplantation, she is alive with no signs of leukemia and no major HSCT-related complications. After excluding any reasonable cause of the ARDS, we considered a cytokine rebound storm after ruxolitinib discontinuation as the cause of the respiratory failure, and on this clinical reasoning we re-introduced ruxolitinib. This led to rapid improvement of the respiratory failure, thereby confirming ex juvantibus that the event was indeed to be attributed to ruxolitinib discontinuation syndrome (RDS). This case underscores the complexity of recognizing and managing the uncommon RDS in cases where related symptoms occur in the settings of very complex clinical condition as it was transformation to AML in this patient with a long history of ET successfully treated with ruxolitinib. In fact, this patient presented with fever and progressive respiratory failure soon after the diagnosis of AML after beginning a careful stepwise tapering of ruxolitinib, as recommended. Among the possible diagnoses, infectious pneumonia is certainly the most likely at presentation, but it is finally excluded by negativity of an extended microbiological work-up as well as the lack of response to antimicrobial/antiviral/antifungal therapy. A working diagnosis of ruxolitinib withdrawal-related ARDS is made and the experimental drug is restarted, followed by rapid dramatic improvement of patient's conditions. ET is associated with dysregulated JAK/STAT signaling, regardless of the underlying driver mutation.11 The JAK-STAT pathway is critically involved in cell growth, survival, development and differentiation of hematopoietic and immune cells, and is implicated in the regulation of cytokine and growth factor synthesis and cytokine receptor-mediated effects.12 Recently, several inhibitors of JAK2 have been developed and showed efficacy in preclinical and clinical studies; currently, ruxolitinib is the only one approved for MF and PV. Dose-related anemia and thrombocytopenia are the main dose-limiting adverse effects which might lead to dose reduction and rarely to treatment discontinuation. Unusual instances of severe adverse events occurring coincident with ruxolitinib withdrawal have been reported and are overall referred to as "ruxolitinib discontinuation syndrome". It includes a constellation of clinical manifestations, ranging from acute relapse of disease-related symptoms, rapid spleen volume enlargement, and worsening of cytopenias, to more severe complications, such as ARDS, disseminated intravascular coagulation (DIC), splenic infarction, and tumor lysis-like syndrome. RDS is overall rare and, to the best of our knowledge, only 9 cases have been reported to date.5, 13-16 Long-term follow-up of the original phase I/II trial reported serious adverse events requiring hospitalization in 5 of 47 patients who discontinued ruxolitinib13; of these, 3 patients developed ARDS, 2 of whom required mechanical ventilation and vasopressor support because of septic shock-like syndrome, while one presented with DIC like-syndrome. In the phase III COMFORT-I study, one patient developed pyrexia, acute respiratory failure and splenic hemorrhage with infarction following ruxolitinib discontinuation.5 Other reports described a patient who developed a tumor lysis-like syndrome,14 a case of ARDS,15 and a case of recurrent respiratory failure that twice resolved after ruxolitinib reintroduction.16 RDS is mainly a diagnosis of exclusion. Indeed, there are no clinical features, laboratory or histopathology findings that are diagnostic; the syndrome can be suspected based on the temporal relationship between drug withdrawal and onset of clinical manifestations, that can appear from less than 24 hours up to 3 weeks after discontinuation. Although pathophysiology is far from being understood, RDS is considered to result from a rapid rebound of inflammatory cytokines. All MPNs, particularly MF, are characterized by important inflammatory activation as demonstrated by the presence of high plasma levels of inflammatory cytokines.17 In a murine model of JAK2V617F-positive MPN, ruxolitinib significantly reduced circulating levels of cytokines, including interleukin (IL)-6 and tumor necrosis factor (TNF)-α18; in clinical studies, beneficial effects of ruxolitinib were associated with marked reduction in plasma levels of various inflammatory cytokines [IL-6, IL-1ra, TNF-α, macrophage inflammatory protein (MIP)-1β, C-reactive protein (CRP)].5, 6 These data suggest that RDS might be mechanistically related to a sudden and dramatic rebound of previously downregulated cytokines' release and/or signaling via JAK2. To prevent RDS, a slow tapering of ruxolitinib eventually associated to corticosteroids is suggested; it should be noted, however, that dose-tapering schedule of ruxolitinib is not guaranteed to universally prevent the development of cytokine-rebound phenomena, as demonstrated by this patient and as reported in previously series.13, 16 In our patient, ruxolitinib therapy was associated with significant improvement of constitutional symptoms and blood counts with optimal tolerance over almost 7 years, but leukemic transformation eventually lead to treatment discontinuation. Deep-sequencing using a 27-gene panel showed the JAK2V617F mutation, VAF 37%, associated with a TET2R1404X variant, VAF 5%, at the time of enrollment in the ruxolitinib trial; both became undetectable 65 months thereafter. Blast cells at the time of AML diagnosis resulted JAK2 and TET2 wild-type but presented a RUNX1R320X mutation, VAF 25%; post-hoc analysis of blood cells at the time of JAK2V617F undetectability revealed that RUNX1 mutation was present with a VAF 0.39%. In conclusion, ruxolitinib is a potent therapeutic resource in the management of selected patients with MPNs but its benefits come necessarily with on-target side effects, such as dose-related cytopenias and potentially serious, yet overall rare, cytokine-related manifestations. The current and previous reports underscore the need for physicians to consider the possible onset of catastrophic RDS and adopt measures to prevent it, by tapering dose and adding steroids, and eventually to recognize and treat it as early as possible, including ex-adjuvantibus reintroduction of ruxolitinib administration. AMV received honoraria from Novartis for board participation and lectures, and institution research funds from Novartis.