Light and shade of ruxolitinib: positive role of early treatment with ruxolitinib and ruxolitinib withdrawal syndrome in patients with myelofibrosis

INTRODUCTION

Myelofibrosis (MF) is characterized by ineffective and hepatosplenic extramedullary hematopoiesis due to fibrotic changes in the bone marrow and systemic manifestations due to aberrant cytokine release. Ruxolitinib (RUX) is the first JAK1/JAK2 inhibitor that is clinically approved to treat splenomegaly by ameliorating inflammatory cytokines and myeloproliferation in MF.

AREAS COVERED

Patients with less advanced MF may also achieve better outcome and successful treatment with RUX. However, approximately 40% of the patients failed to achieve a stable response or have shown to be intolerant to RUX, and most of them discontinued RUX. In patients who need to discontinue or reduce the dose of RUX for any reason, RUX is known to induce a paradoxical accumulation of JAK activation loop phosphorylation that is causing RUX discontinuation syndrome (RDS). To review the topic of MF and RUX, we searched relevant literatures using PubMed.

EXPERT OPINION

RUX treatment in lower IPSS risk patients who present with splenomegaly and disease-associated symptoms can be helpful. A careful discontinuation strategy with steroids may reduce the probability of RDS, and the recognition of RDS with early re-introduction of RUX is important in the treatment of severe cases of RDS.

Case report: Pulse cyclophosphamide for treatment of multi-agent-refractory hepatic graft-versus-host disease

Graft-versus-host disease (GVHD) is a common complication in patients receiving allogeneic hematopoietic stem cell transplantation (HSCT). GVHD is characterized as either acute or chronic based on symptomatology and histopathological findings. Despite advancements in disease-targeting therapeutics, steroid-refractory GVHD remains a significant contributor to mortality in HSCT recipients, highlighting the gaps in our understanding of its pathophysiology and treatment strategies. We present the case of a 46-year-old woman diagnosed with acute undifferentiated leukemia, who exhibited persistently elevated levels of serum total bilirubin (T.Bili), alkaline phosphatase (ALP), and liver function tests (LFTs) beginning on [day +201] post-haploidentical peripheral blood stem cell (PBSC) transplantation. The patient received fludarabine/total body irradiation (Flu/TBI) as a myeloablative conditioning regimen and post-transplant cyclophosphamide/tacrolimus/mycophenolate mofetil (PTCy/Tac/MMF) as GVHD prophylaxis. A liver biopsy confirmed the diagnosis of GVHD, while other possible etiologies were excluded by corresponding tests. Initial treatment with prednisone and tacrolimus, and the later addition of ruxolitinib, all showed poor response indicated by worsening T.Bili, ALP, and LFTs at the same time. Based on a multidisciplinary comprehensive assessment, we decided to administer 1,000 mg/m2 (1,600 mg) of cyclophosphamide ("pulse Cy"), which resulted in a dramatic improvement in T.Bili and transaminases starting from the very next day. A durable response to pulse cyclophosphamide was observed, as all indicators normalized ("complete response") within 55 days without relapses. The patient remains in good health with no recurrence of hepatic GVHD. To our knowledge, this is the first case in which Grade IV hepatic GVHD, refractory to multiple agents including steroids, tacrolimus, and ruxolitinib, demonstrated a complete response to pulse cyclophosphamide. The success highlights the potential therapeutic role of cyclophosphamide, a potent and cost-effective chemotherapy agent, in treating multi-agent-refractory GVHD. Large-scale clinical trials are warranted to validate its efficacy in this setting.

The evolving landscape of polycythemia vera therapies

INTRODUCTION

The treatment landscape of polycythemia vera (PV) has seen major advancements within the last decade including approval of ruxolitinib in the second line setting after hydroxyurea, ropegylated interferon-α2b, and advanced clinical development of a novel class of agents called hepcidin mimetics.

AREAS COVERED

We provide a comprehensive review of the evidence discussing the risk stratification, treatment indications, role and limitations of phlebotomy only approach and pivotal trials covering nuances related to the use of interferon-α (IFN-α), ruxolitinib, hepcidin mimetics, and upcoming investigational agents including HDAC and LSD1 inhibitors.

EXPERT OPINION

The research paradigm in PV is slowly shifting from the sole focus on hematocrit control and moving toward disease modification. The discovery of hepcidin mimetics has come as a breakthrough in restoring iron homeostasis, achieving phlebotomy-independence and may lead to improved thrombosis-free survival with stricter hematocrit control. On the other hand, emerging data with IFN- α and ruxolitinib as well as combination of the two agents suggests the potential for achieving molecular remission in a subset of PV patients and long-term follow-up is awaited to validate the correlation of molecular responses with clinically relevant outcomes of progression-free and thrombosis-free survival.

EBV-Gastritis Preceded the Development of Nasopharyngeal EBV (+) Diffuse Large B Cell Lymphoma in a Patient With Ruxolitinib-Induced Immunosuppression

Epstein-Barr virus (EBV) is acquired early in life as asymptomatic or symptomatic infectious mononucleosis (IM) and remains latent in a few B cells in most individuals. Pathologic EBV-reactivation affects immunosuppressed individuals and manifests as IM-like syndromes, polyclonal lymphoproliferative disorders, EBV-related lymphomas, and carcinomas. EBV-associated gastritis is an underrecognized and very rarely reported entity. We report a case of a 65-year-old woman with ruxolitinib-treated polycythemia vera, who developed EBV viremia and EBV gastritis. The patient improved after the ruxolitinib dose reduction and administration of antiviral therapy. A few months after discontinuation of the antiviral therapy the gastric symptoms recurred, numerous gastric ulcers were identified, and a nasopharyngeal mass was detected. A biopsy of the nasopharynx showed an EBV (+) diffuse large B cell lymphoma. Ruxolitinib was discontinued and the patient was started on rituximab monotherapy with a resolution of symptoms and pathologic improvement. Our case supports earlier reports of an association of ruxolitinib therapy with EBV complications. An early diagnosis of EBV gastritis in immunocompromised patients is important since the gastric infection may precede or co-exist with a developing EBV-associated malignancy. Our case and existing literature suggest that EBV gastritis in symptomatic patients with iatrogenic immunosuppression requires discontinuation of immunosuppressive therapy if feasible, treatment with antivirals, and close surveillance for possible evolving/concurrent EBV (+) malignancy.

Tapinarof cream (Vtama) for atopic dermatitis

Tapinarof 1% cream (Vtama – Dermavant), an aryl hydrocarbon receptor (AhR) agonist, has been approved by the FDA for topical treatment of atopic dermatitis in patients ≥2 years old. Tapinarof is the first AhR agonist to be approved in the US for this indication. It was approved in 2022 for treatment of plaque psoriasis in adults.

Efficacy and safety of ruxolitinib in patients with myelofibrosis: a retrospective and multicenter experience in Turkey

Background/aim

The aim of this study is to assess the efficacy and safety of ruxolitinib in patients with myelofibrosis.

Materials and methods

From 15 centers, 176 patients (53.4% male, 46.6% female) were retrospectively evaluated.

Results

The median age at ruxolitinib initiation was 62 (28–87) and 100 (56.8%) of all were diagnosed as PMF. Constitutional symptoms were observed in 84.7%. The median initiation dose of ruxolitinib was 30 mg (10–40). Dose change was made in 69 (39.2%) patients. Forty seven (35.6%) and 20 (15.2%) of 132 patients had hematological and nonhematological adverse events, respectively. The mean spleen sizes before and after ruxolitinib treatment were 219.67 ± 46.79 mm versus 199.49 ± 40.95 mm, respectively (p < 0.001). There was no correlation between baseline features and subsequent spleen response. Overall survival at 1-year was 89.5% and the median follow up was 10 (1–55) months. We could not show any relationship between survival and reduction in spleen size (p = 0.73).

Conclusion

We found ruxolitinib to be safe, well tolerated, and effective in real-life clinical practice in Turkey. Ruxolitinib dose titration can provide better responses in terms of not only clinical benefit but also for long term of ruxolitinib treatment.

The Promise of JAK Inhibitors for Treatment of Sarcoidosis and Other Inflammatory Disorders with Macrophage Activation: A Review of the Literature

Certain inflammatory disorders are characterized by macrophage activation and accumulation in tissue; sometimes leading to the formation of granulomas, as in sarcoidosis. These disorders are often difficult to treat and more effective, molecularly targeted therapies are needed. Recent work has shown that overproduction of inflammatory cytokines, such as interferon gamma (IFN-γ) leading to constitutive activation of the JAK-STAT pathway may be a conserved feature of these disorders. Use of JAK inhibitors, which can block these signals, has resulted in dramatic improvement in several patients with sarcoidosis. JAK inhibitors also appear to have activity in other inflammatory disorders with macrophage activation including hemophagocytic lymphohistiocystosis, Crohn's disease, granuloma annulare, and necrobiosis lipoidica. Here, we review the role of JAK dependent cytokines in macrophage activation and granuloma formation and the clinical evidence supporting the use of JAK inhibition in these disorders. Ongoing efforts to evaluate role of JAK inhibitors in these disorders is also discussed.

A case of pachydermaperiostosis with myelofibrosis and treatment with ruxolitinib

Pachydermaperiostosis (PDP) is a rare condition of connective tissue presenting with abnormal skin and skeletal findings that usually occur as a complication of an underlying disease, especially malignancies. We described a case of a patient with severe transfusion-dependent anemia and both skin and joint findings, diagnosed as PDP. The haematological assessment revealed myelofibrosis as the underlying disease, and treatment with ruxolitinib as the first-line choice was given by skipping hydroxyurea due to pancytopenia. The patient got benefits in arthralgia and amelioration of pancytopenia and a reduced spleen volume was observed, despite the negative result for JAK2 gene mutation. This is the first case of ruxolitinib being used in PDP with myelofibrosis, and it highlights the importance of evaluating PDP as not just a skin and joint problem but a result of systemic disease and individual-based treatment.

Ruxolitinib for myelofibrosis in elderly non-transplant patients: healthcare resource utilization and costs

AIM

This study evaluated real-world healthcare resource utilization (HCRU), direct costs, and overall survival (OS) of patients who were Medicare beneficiaries and were newly diagnosed with myelofibrosis (MF) who filled ≥1 prescription of ruxolitinib versus those who did not.

PATIENTS AND METHODS

This was a study of the US Medicare fee-for-service database. Beneficiaries were aged ≥65 years with an MF diagnosis (index) between January 1, 2012-December 31, 2017. Data were summarized descriptively. OS was estimated using Kaplan-Meier analysis.

RESULTS

Patients with ≥1 prescription fill of ruxolitinib (n = 2787) had lower mean rates (per patient per month [PPPM]) versus patients who did not fill a prescription for ruxolitinib (n = 7262) for hospitalizations (0.16 vs 0.32), length of inpatient stay (0.16 vs 2.44 days), emergency department visits (0.10 vs 0.14), physician office visits (4.68 vs 6.25), skilled nursing facility stays (0.02 vs 0.12), home health/durable medical equipment services (0.32 vs 0.47), and hospice visits (0.30 vs 1.70). Monthly medical costs were numerically lower in patients who had ≥1 fill of ruxolitinib versus those who did not fill a prescription for ruxolitinib ($6553 vs $12,929), largely driven by inpatient costs ($3428 vs $6689). Pharmacy costs were $10,065 and $987 in patients who filled versus did not fill ≥1 prescription for ruxolitinib, respectively; total PPPM all-cause healthcare costs were $16,618 and $13,916, respectively. The median OS was 37.5 and 18.7 months for the cohorts of patients who filled versus did not fill ≥1 prescription for ruxolitinib, respectively (hazard ratio, 0.63, 95% CI, 0.59-0.67).

CONCLUSIONS

Ruxolitinib is associated with reduced HCRU and direct costs of medical care in addition to increased survival, suggesting it to be a cost-effective advance for patients with MF.

Dermatologic Applications and Safety Considerations of Janus Kinase Inhibitors

Janus kinase inhibitors, also known as JAK inhibitors or jakinibs, represent a new class of medication that have broad potential to treat dermatologic disease. Currently, the only FDA-approved dermatologic indication for this class of medications is psoriatic arthritis; however, their utility in treating other immune-mediated skin conditions including atopic dermatitis, vitiligo, alopecia areata, and systemic and cutaneous lupus is actively being investigated. Overall, these drugs appear to be well-tolerated and have a safety profile similar to that of other biologics commonly used in dermatologic practice, although an increased risk of thromboembolism has been associated. While risk of mild infection and herpes zoster appears to be increased regardless of JAK selectivity, risk of thrombosis and malignancy based on the subtype of JAK inhibition remains to be seen. Certainly, safety concerns warrant further investigation; however, early data from ongoing clinical trials offer promise for the broad utility of these medications within future dermatologic practice.

Characterizing the Bone Marrow Environment in Advanced-Stage Myelofibrosis during Ruxolitinib Treatment Using PET/CT and MRI: A Pilot Study

Current diagnostic criteria for myelofibrosis are largely based on bone marrow (BM) biopsy results. However, these have several limitations, including sampling errors. Explorative studies have indicated that imaging might form an alternative for the evaluation of disease activity, but the heterogeneity in BM abnormalities complicates the choice for the optimal technique. In our prospective diagnostic pilot study, we aimed to visualize all BM abnormalities in myelofibrosis before and during ruxolitinib treatment using both PET/CT and MRI. A random sample of patients was scheduled for examinations at baseline and after 6 and 18 months of treatment, including clinical and laboratory examinations, BM biopsies, MRI (T1-weighted, Dixon, dynamic contrast-enhanced (DCE)) and PET/CT ([¹⁵O]water, [¹⁸F]NaF)). At baseline, all patients showed low BM fat content (indicated by T1-weighted MRI and Dixon), increased BM blood flow (as measured by [¹⁵O]water PET/CT), and increased osteoblastic activity (reflected by increased skeletal [¹⁸F]NaF uptake). One patient died after the baseline evaluation. In the others, BM fat content increased to various degrees during treatment. Normalization of BM blood flow (as reflected by [¹⁵O]water PET/CT and DCE-MRI) occurred in one patient, who also showed the fastest clinical response. Vertebral [¹⁸F]NaF uptake remained stable in all patients. In evaluable cases, histopathological parameters were not accurately reflected by imaging results. A case of sampling error was suspected. We conclude that imaging results can provide information on functional processes and disease distribution throughout the BM. Differences in early treatment responses were especially reflected by T1-weighted MRI. Limitations in the gold standard hampered the evaluation of diagnostic accuracy.

Carfilzomib Enhances the Suppressive Effect of Ruxolitinib in Myelofibrosis

As the first FDA-approved tyrosine kinase inhibitor for treatment of patients with myelofibrosis (MF), ruxolitinib improves clinical symptoms but does not lead to eradication of the disease or significant reduction of the mutated allele burden. The resistance of MF clones against the suppressive action of ruxolitinib may be due to intrinsic or extrinsic mechanisms leading to activity of additional pro-survival genes or signalling pathways that function independently of JAK2/STAT5. To identify alternative therapeutic targets, we applied a pooled-shRNA library targeting ~5000 genes to a JAK2^V617F-positive cell line under a variety of conditions, including absence or presence of ruxolitinib and in the presence of a bone marrow microenvironment-like culture medium. We identified several proteasomal gene family members as essential to HEL cell survival. The importance of these genes was validated in MF cells using the proteasomal inhibitor carfilzomib, which also enhanced lethality in combination with ruxolitinib. We also showed that proteasome gene expression is reduced by ruxolitinib in MF CD34⁺ cells and that additional targeting of proteasomal activity by carfilzomib enhances the inhibitory action of ruxolitinib in vitro. Hence, this study suggests a potential role for proteasome inhibitors in combination with ruxolitinib for management of MF patients.

Case Report: Infectious prophylaxis in hematological malignancies

Patients with hematological malignancies and past serological evidence of hepatitis B are at risk for HBV reactivation. In myeloproliferative neoplasms, continuous treatment with the JAK 1/2 inhibitor ruxolitinib confers a moderate risk of reactivation (1-10%); nevertheless, no prospective randomized data are available to strongly recommend HBV prophylaxis in these patients. Here, we report a case of primary myelofibrosis and past serological evidence of HBV infection, treated with ruxolitinib and concomitant lamivudine, developing HBV reactivation due to premature withdrawal of prophylaxis. This case underlines the potential need for persistent HBV prophylaxis in the setting of ruxolitinib treatment.

The Inhibition of Glycolysis in T Cells by a Jak Inhibitor Ameliorates the Pathogenesis of Allergic Contact Dermatitis in Mice

Allergic contact dermatitis (ACD) and atopic dermatitis develop through delayed-type hypersensitivity reactions mediated by T cells. The development of immunomodulatory drugs, such as Jak inhibitors, would be useful for the long-term management of these diseases owing to their profile of favorable adverse effects. However, the efficacy of Jak inhibitors for ACD treatment has not been fully determined under a variety of settings. Therefore, we evaluated the effects of ruxolitinib, a Jak inhibitor for Jak1 and Jak2, using a mouse ACD model. As a result, the lower numbers of immune cells, including CD4+ T cells, CD8+ T cells, neutrophils, and possibly macrophages, as well as milder pathophysiological aspects have been observed in the inflamed skin of ACD with the administration of ruxolitinib. In addition, the treatment of differentiating T cells with ruxolitinib downregulated the level of IL-2-mediated glycolysis in vitro. Furthermore, symptoms of ACD did not develop in T-cell-specific Pgam1-deficient mice whose T cells had no glycolytic capacity. Taken together, our data suggest that the downregulation of glycolysis in T cells by ruxolitinib could be an important factor in the suppression of ACD development in mice.

Cellular and transcriptional impacts of Janus kinase and/or IFN-gamma inhibition in a mouse model of primary hemophagocytic lymphohistiocytosis

Background

Primary hemophagocytic lymphohistiocytosis (pHLH) is an inherited inflammatory syndrome driven by the exuberant activation of interferon-gamma (IFNg)-producing CD8 T cells. Towards this end, ruxolitinib treatment or IFNg neutralization (aIFNg) lessens immunopathology in a model of pHLH in which perforin-deficient mice (Prf1-/-) are infected with Lymphocytic Choriomeningitis virus (LCMV). However, neither agent completely eradicates inflammation. Two studies combining ruxolitinib with aIFNg report conflicting results with one demonstrating improvement and the other worsening of disease manifestations. As these studies used differing doses of drugs and varying LCMV strains, it remained unclear whether combination therapy is safe and effective.

Methods

We previously showed that a ruxolitinib dose of 90 mg/kg lessens inflammation in Prf1-/- mice infected with LCMV-Armstrong. To determine whether this dose controls inflammation induced by a different LCMV strain, we administered ruxolitinib at 90mg/kg to Prf1-/- mice infected with LCMV-WE. To elucidate the impacts of single agent versus combination therapy, Prf1-/- animals were infected with LCMV, treated or not with ruxolitinib, aIFNg or both agents, and analyzed for disease features and the transcriptional impacts of therapy within purified CD8 T cells.

Results

Ruxolitinib is well-tolerated and controls disease regardless of the viral strain used. aIFNg, administered alone or with ruxolitinib, is most effective at reversing anemia and reducing serum IFNg levels. In contrast, ruxolitinib appears better than aIFNg, and equally or more effective than combination therapy, at lessening immune cell expansion and cytokine production. Each treatment targets distinct gene expression pathways with aIFNg downregulating IFNg, IFNa, and IL-6-STAT3 pathways, and ruxolitinib downregulating IL-6-STAT3, glycolysis, and reactive oxygen species pathways. Unexpectedly, combination therapy is associated with upregulation of genes driving cell survival and proliferation.

Conclusions

Ruxolitinib is tolerated and curtails inflammation regardless of the inciting viral strain and whether it is given alone or in combination with aIFNg. When administered at the doses used in this study, the combination of ruxolitinb and aIFNg appears no better than treatment with either drug alone in lessening inflammation. Further studies are warranted to elucidate the optimal doses, schedules, and combinations of these agents for the treatment of patients with pHLH.

Effect of Immune-Modulatory Interventions on Asymptomatic Cytomegalovirus Shedding During Suppressive Antiretroviral Therapy

Long-term consequences of human immunodeficiency virus (HIV) are likely the result of persistent inflammation and immune dysfunction of which cytomegalovirus (CMV) is a known contributor. We leveraged 2 AIDS Clinical Trials Group clinical trials exploring the effects of immune modulators (ruxolitinib and sirolimus) on inflammation in people with HIV on antiretroviral therapy to determine whether these interventions affected CMV shedding at various mucosal sites. Analyzing 635 mucosal samples collected, we found no significant difference in CMV levels across study arms or time points. Men had more CMV shedding than women. We did confirm an association between higher CMV DNA and immune markers associated with HIV persistence and HIV-associated mortality rates.

Updates on efficacy and safety janus kinase inhibitors in juvenile dermatomyositis

INTRODUCTION

Juvenile dermatomyositis (JDM) is a rare autoimmune disease most commonly with proximal weakness due to inflammation and characteristic skin rashes. Most patients have a chronic or polycyclic disease course on standard therapy so better treatments are needed. An interferon signature is well-established in key tissues of JDM. Janus kinase inhibitors (jakinibs), which can decrease IFN signaling, are therefore appealing as a targeted therapy.

AREAS COVERED

Herein is a review of the growing literature on JDM patients in jakinibs, including specifics of their jakinib exposure, summary of efficacy, disease features, and characteristics of patients treated, and safety parameters.

EXPERT OPINION

The vast majority of refractory JDM patients respond to jakinib therapy, though they have varied features, doses, and previous/concurrent medications, and data is largely retrospective. Jakinibs are an exciting and promising treatment in JDM. Evaluation with larger prospective controlled studies is needed to answer remaining questions about jakinibs in JDM regarding dosing, which JDM patients to treat with jakinibs, potential biomarkers to use, and how best to monitor safety risks in JDM.

JAK inhibitors to treat STAT3 gain-of-function: a single-center report and literature review

Objective

The signal transducer and activator of transcription 3 (STAT3) gain-of-function (GOF) syndrome (STAT3-GOF) is an inborn error of immunity (IEI) characterized by diverse manifestations of immune dysregulation that necessitate systemic immunomodulatory treatment. The blockade of the interleukin-6 receptor and/or the inhibition of the Janus kinases has been commonly employed to treat diverse STAT3-GOF-associated manifestations. However, evidence on long-term treatment outcome, especially in the case of adult patients, is scarce.

Methods

Clinical data, including laboratory findings and medical imaging, were collected from all seven patients, diagnosed with STAT3-GOF, who have been treated at the Hannover University School, focusing on those who received a Janus kinase (JAK) inhibitor (JAKi). Previously published cases of STAT3-GOF patients who received a JAKi were evaluated, focusing on reported treatment efficacy with respect to diverse STAT3-GOF-associated manifestations of immune dysregulation and safety.

Results

Five out of seven patients diagnosed with STAT3-GOF were treated with a JAKi, each for a different indication. Including these patients, outcomes of JAKi treatment have been reported for a total of 41 patients. Treatment with a JAKi led to improvement of diverse autoimmune, inflammatory, or lymphoproliferative manifestations of STAT3-GOF and a therapeutic benefit could be documented for all except two patients. Considering all reported manifestations of immune dysregulation in each patient, complete remission was achieved in 10/41 (24.4%) treated patients.

Conclusions

JAKi treatment improved diverse manifestations of immune dysregulation in the majority of STAT3-GOF patients, representing a promising therapeutic approach. Long-term follow-up data are needed to evaluate possible risks of prolonged treatment with a JAKi.

Comparison of the crystal structures of the JAK1/2 inhibitor ruxolitinib and its hydrate and phosphate

Ruxolitinib {RUX; systematic name: (3R)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]propanenitrile, C17H18N6} is an orally bioavailable JAK1/2 inhibitor approved for treating intermediate- or high-risk myelofibrosis (MF) and high-risk polycythemia vera (PV). Recent patents claim that RUX can exist in many different forms, information for which is important for the clinical utilization of RUX, especially for the formulation and bioavailability of the drug. But there has been no detailed study on its forms so far. Herein crystals of RUX and its dihydrate (RUX-2H; C17H18N6·2H2O) and phosphate (RUX-P; systematic name: 4-{1-[(1R)-2-cyano-1-cyclopentylethyl]-1H-pyrazol-4-yl}-7H-pyrrolo[2,3-d]pyrimidin-3-ium dihydrogen phosphate, C17H19N6+·H2PO4-) were prepared successfully and their structures studied in detail for the first time. Our study shows that the three crystals of RUX differ in the orientation of the pyrimidine ring relative to the pyrazole ring of the RUX molecule, and in their hydrogen-bond interactions. The water molecules in RUX-2H and the dihydrogen phosphate anion in RUX-P enrich the hydrogen-bond networks in these forms. The expected proton transfer occurs in RUX phosphate and the protonated N atom is engaged in a charge-assisted hydrogen bond with the counter-anion. Hydrogen-bonding interactions dominate in the crystal packing of the three forms. The detailed conformations and packing of the three forms were compared through the calculation of both Hirshfeld surfaces and fingerprint plots.

Ten years of experience with ruxolitinib since approval for polycythemia vera: A review of clinical efficacy and safety

The oral Janus kinase (JAK) 1/JAK2 inhibitor ruxolitinib was approved by the US Food and Drug Administration in 2014 for treatment of patients with polycythemia vera (PV) who have an inadequate response to or intolerance of hydroxyurea (HU). PV is a chronic myeloproliferative neoplasm defined by primary absolute erythrocytosis, bone marrow hypercellularity, and JAK mutations such as JAK2V617F. Patients with PV experience burdensome symptoms and are at risk of thromboembolic events, in particular those with resistance to or intolerance of initial treatments such as HU. Other risks for patients with PV include progression of disease to more aggressive forms with worse prognoses, such as myelofibrosis or blast-phase myeloproliferative neoplasms. This review summarizes the efficacy and safety of ruxolitinib from key phase 2 and 3 trials (MAJIC-PV, RESPONSE, RESPONSE-2, RELIEF, and Ruxo-BEAT), large real-world studies, and a decade of postmarketing surveillance safety data. The authors focus on improved blood count control, rates of thromboembolic events, symptom improvement, and markers of disease modification such as reduction of JAK2V617F allele burden in patients treated with ruxolitinib. They also discuss the well-characterized safety profile of ruxolitinib regarding hematologic and other adverse events of interest. In the 10 years since its approval, ruxolitinib remains a safe and effective standard-of-care treatment for PV. As the treatment landscape for PV continues to evolve in the coming years, the efficacy and safety profiles of ruxolitinib suggest it will remain a preferred treatment as monotherapy and as a potential backbone of future combination regimens.