Janus Kinase Inhibitor Ruxolitinib Research Articles

Momelotinib vs. ruxolitinib in myelofibrosis patient subgroups by baseline hemoglobin levels in the SIMPLIFY-1 trial

A key hallmark of myelofibrosis is anemia, which ranges from mild to severe based on hemoglobin levels. To more clearly define outcomes with the Janus kinase (JAK) 1/JAK2/activin A receptor type 1 inhibitor momelotinib by anemia severity, we performed a descriptive post hoc exploratory analysis of the double-blind, randomized, phase 3 SIMPLIFY-1 study (NCT01969838; N = 432, JAK inhibitor naive, momelotinib vs. ruxolitinib); subgroups were defined by baseline hemoglobin: <10 (moderate/severe), ≥10 to <12 (mild), or ≥12 g/dL (nonanemic). Spleen and symptom results were generally consistent with those previously reported for the intent-to-treat population. In anemic subgroups, momelotinib was associated with higher rates of transfusion independence and reduced/stable transfusion intensity vs. ruxolitinib. No new or unexpected safety signals were identified. Overall, momelotinib provides spleen, symptom, and anemia benefits to JAK inhibitor-naive patients with myelofibrosis regardless of baseline hemoglobin level, and greater anemia-related benefits vs. ruxolitinib in patients with hemoglobin <12 g/dL.

Preclinical and clinical evaluation of the Janus Kinase inhibitor ruxolitinib in multiple myeloma.

Multiple myeloma (MM) is the most common primary malignancy of the bone marrow. No established curative treatment is currently available for patients diagnosed with MM. In recent years, new and more effective drugs have become available for the treatment of this B-cell malignancy. These new drugs have often been evaluated together and in combination with older agents. However, even these novel combinations eventually become ineffective; and, thus, novel therapeutic approaches are necessary to help overcome resistance to these treatments. Recently, the Janus Kinase (JAK) family of tyrosine kinases, specifically JAK1 and JAK2, has been shown to have a role in the pathogenesis of MM. Preclinical studies have demonstrated a role for JAK signaling in direct and indirect growth of MM and downregulation of anti-tumor immune responses in these patients. Also, inhibition of JAK proteins enhances the anti-MM effects of other drugs used to treat MM. These findings have been confirmed in clinical studies which have further demonstrated the safety and efficacy of JAK inhibition as a means to overcome resistance to currently available anti-MM therapies. Additional studies will provide further support for this promising new therapeutic approach for treating patients with MM.

Real-World Data Suggest Effectiveness of Allogeneic Mesenchymal Stromal (MSC-FFM) Cells in Ruxolitinib-Refractory Acute Graft-Versus-Host Disease

Introduction: Acute graft-versus-host disease (aGvHD) remains the leading cause of treatment-related morbidity and mortality after allogeneic hematopoietic stem cell transplantation. Current first-line treatment of aGvHD is with high-dose corticosteroids, the standard for steroid-refractory aGvHD (SR-aGvHD) is the Janus kinase (JAK) inhibitor ruxolitinib. Outcomes for patients with ruxolitinib-refractory or -intolerant aGvHD (RR-aGvHD) are poor. Thus in a recent real-world study of adult patients with RR-aGvHD (Abedin BJH 2021) median survival was 28 days (21 days for ruxolitinib refractoriness, 50 days for ruxolitinib intolerance), the probability of overall survival (OS) at 6, 12, and 24 months were about 20%, 16%, and 10%, respectively. We assessed real-world outcomes of patients with RR-aGvHD treated with the random-donor allogeneic MSC preparation “MSC-FFM,” available via Hospital Exemption in Germany. Patients: Between December 2017 and February 2023, 156 patients, including 33 children and adolescents (&amp;lt;18 years of age), received MSC-FFM for RR-aGvHD. Thirty-two German sites contributed 139 patients, while the remaining 17 patients came from seven transplant centers in France, Hungary, Norway, Sweden, and Switzerland. The adult cohort (n=123) consisted of 41% females, with an age range of 19 to 79 years (median 55 years). Except for one patient, all had been diagnosed with malignant diseases (missing information, n=3). Among the adult patients with malignant diseases, 88% (n=105) received HSCT for acute myeloid leukemia (AML), advanced myelodysplastic syndrome, myeloproliferative neoplasm or lymphoma, and 12% (n=15) for acute lymphoblastic leukemia (ALL). In the pediatric cohort (n=33), 48% of patients were females, with an age range of 0 to 17 years (median 9 years). Overall, 58% of pediatric patients (n=19) had malignant diseases as the indication for allogeneic HSCT, 42% (n=8) having ALL and 32% (n=6) with AML. The remaining 42% of pediatric patients (n=14) had non-malignant diseases as the indication for HSCT. Of the adult patients, 6 (4.9%) had grade II, 52 (42.3%) had grade III, and 63 (51.2%) had grade IV aGvHD, with no specification reported for 2 patients (1.6%). In children, 2 (6.1%) had grade II, 10 (30.3%) had grade III, and 21 (63.6%) had grade IV Treatment: MSC-FFM is manufactured from pooled bone marrow mononuclear cells from eight HLA-disparate healthy donors. MSCs are selected by plastic adherence, expanded until the end of passage 3, then frozen in saline-albumin with DMSO. The recommended dosing for MSC-FFM is 1-2 million cells/kg body weight (BW), for four weekly doses. The median dose administered was 1.18 million cells/kg BW, with a median number of four doses and a median inter-dose interval of 7 days. Results: Safety: Tolerability of MSC-FFM was good, with only five adverse drug reactions reported in three adult patients (chills, BK virus cystitis, increase in C-reactive protein [reported twice in one patient], nausea) and did not result in cessation of MSC treatment or dose reductions. Response: The overall response rate at day +28 was 49% (95%-CI: 41-58%), with 45% (36-55%) in adults and 64% (45-80%) in children. Most responses were durable, resulting in an overall response rate of 49% (41-57%) for both adults and children at 2 months, and 40% (31-48%) at 6 months. Survival: Overall survival at 6, 12, and 24 months was 47% (38-56%), 35% (27-44%), and 29% (21-38%) for adults, and 59% (40-74%), 42% (24-58%), and 37% (19-54%) for children, respectively (Table 1). Median overall survival was 5.8 months. These outcomes compare favourably to published overall survival estimates for adult RR-aGvHD patients not treated with MSC-FFM (Abedin BJH, see above). Summary: The unique MSC-preparation MSC-FFM appears to be effective against RR-aGvHD.

Efficacy and Safety of Fedratinib in Patients with Myelofibrosis Previously Treated with Ruxolitinib: Results from the Phase 3 Randomized FREEDOM2 Study

Introduction Patients (pts) with myelofibrosis (MF) treated with the Janus kinase inhibitor (JAKi) ruxolitinib (RUX) show spleen volume reduction (SVR) and symptom reduction. However, most develop RUX intolerance or relapsed/refractory (R/R) disease and survival rates after RUX discontinuation are poor. Fedratinib (FEDR) delivered SVR and symptom reduction in the JAKARTA2 and FREEDOM studies (C Harrison et al. Am J Hematol 2020; V Gupta et al. Blood 2022). FREEDOM2 (NCT03952039) was a phase 3, open-label, randomized study to evaluate the safety and efficacy of FEDR compared with best available therapy (BAT) in pts with MF previously treated with RUX. Methods Pts aged ≥ 18 years with primary, post-polycythemia vera, or post-essential thrombocythemia MF with Dynamic International Prognostic Scoring System (DIPSS) score ≥ intermediate-2, splenomegaly (≥ 450 cm 3), platelets ≥ 50 x 10 9/L, peripheral blood myeloblasts &amp;lt; 5%, and normal baseline thiamine, R/R or intolerant to RUX, were randomized 2:1 to FEDR 400 mg/day or BAT in 28-day cycles, with stratification by spleen size, platelet count, and RUX R/R vs intolerant. Crossover to FEDR was permitted for progressive disease or after cycle 6 (EOC6) response assessment. Pts were treated until intolerance or lack of efficacy and followed-up every 3 months until death, withdrawal of consent, or study closure. The primary endpoint was SVR ≥ 35% (SVR35) at EOC6; secondary endpoints included symptom response (≥ 50% reduction in total symptom score measured by Myelofibrosis Symptom Assessment Form), SVR ≥ 25% (SVR25), durability of SVR and symptom response, and safety. Results Overall, 201 pts were initially randomized and treated, 134 and 67 pts in the FEDR and BAT arms, respectively; subsequently, 46 (68.7%) pts from the BAT arm crossed over to FEDR. Median (interquartile range) age was 70 (64-74) years, 52.2% were male, and most had primary MF (54.7%) and intermediate-2 DIPSS risk (76.1%). Assessed by aggregated group, most pts in the BAT arm received RUX (70.1%), hydroxyurea (10.4%), or RUX plus hydroxyurea (7.5%). At the data cutoff of December 27, 2022 (median follow-up, 15 months), pts receiving FEDR had significantly higher rates of SVR35 at EOC6 compared with BAT (35.8% vs 6.0%; P &amp;lt; 0.0001), as well as superior SVR25 at EOC6 and SVR35 during the full treatment course ( Table, Figure). SVR35 benefit with FEDR was observed across subgroups. The FEDR arm also showed higher rates of symptom response at EOC6 compared with BAT (34.1% vs 16.9%; P = 0.0033; Table). Median treatment duration was 43 weeks of FEDR and 24.7 weeks of BAT. During the first 6 cycles in the safety population: 70 (52.2%) pts on FEDR and 20 (29.9%) pts on BAT had dose interruption/reduction; median time to first reduction/interruption was 44.0 days for FEDR and 56.5 days for BAT. Treatment-emergent adverse events (TEAEs) leading to permanent treatment discontinuation occurred in 13 (9.7%) and 4 (6.0%) pts in the FEDR and BAT arms, respectively, during the first 6 cycles. During the first 6 cycles, 132 (98.5%) pts on FEDR and 65 (97.0%) pts on BAT had ≥ 1 TEAE; treatment-related AEs (TRAEs) occurred in 109 (81.3%) and 23 (34.3%) pts in the FEDR and BAT arms, respectively. The most frequently occurring TRAEs with FEDR were diarrhea (38.1% FEDR vs 0.0% BAT) and nausea (32.1% FEDR vs 1.5% BAT); most cases were grade 1/2. Grade 3/4 TRAEs occurred in 52 (38.8%) pts in FEDR and 8 (11.9%) pts in BAT arms, most frequently thrombocytopenia (11.9% FEDR vs 3.0% BAT) and anemia (9.0% FEDR vs 9.0% BAT). In the FEDR arm, 22 (16.4%) pts had thiamine levels below normal range, compared with 2 (3.0%) pts receiving BAT; most cases occurred prior to the study amendment of prophylactic thiamine supplementation. There was a single grade 1 case of suspected Wernicke's encephalopathy in the FEDR arm during cycle 3, which resolved fully 24 hours after thiamine supplementation (0 cases in BAT arm). Two pts each in FEDR and BAT arms had TRAEs of infection. Conclusions In this phase 3 randomized study in pts with MF and prior RUX treatment, FEDR demonstrated superior SVR and symptom response rates compared with BAT. Most pts on BAT received RUX, highlighting a clinical need for an alternative JAKi. Differences in AE and discontinuation rates in the first 6 cycles are consistent with other studies comparing JAKi with BAT. AE mitigation strategies were effective and no new safety concerns for FEDR were identified. Study support Bristol Myers Squibb

Novel Vehicles For Drug Delivery in Atopic Dermatitis: A Narrative Review.

Atopic dermatitis (AD) causes dry and itchy skin and inflammation that severely impairs the quality of life of affected children and adults. While topical glucocorticosteroid application is typically the first-line treatment of choice, steroid treatment is associated with side effects and, increasingly, patient concerns about prolonged use. Novel drugs and drug delivery vehicles are required for patients with AD. To summarize the current literature on novel topical agents for atopic dermatitis and novel delivery vehicles. A literature search was conducted, and a narrative review was compiled to summarize recent evidence. Novel topical drugs approved or in late-phase clinical trials for the treatment of AD include the Janus kinase inhibitor ruxolitinib, the phosphodiesterase-4 inhibitors crisaborole, and roflumilast, and the aryl hydrocarbon receptor activator tapinarof. While current topical drugs for AD are delivered via creams, ointments, gels, and related vehicles, novel delivery approaches such as electrospun patches, sprays, liposomes, nanoparticles, and lasers are being developed to enhance transdermal delivery, reduce side effects, and increase treatment adherence. Topical application of creams or ointments is currently the predominant vehicle for the delivery of atopic dermatitis drugs. In vitro studies on novel vehicles show promising results to overcome the issues associated with topical delivery. Still, these findings have to be corroborated by controlled studies with human patients in the future.

C-terminal variants in CDC42 drive type I interferon-dependent autoinflammation in NOCARH syndrome reversible by ruxolitinib

C-terminal variants in CDC42 encoding cell division control protein 42 homolog underlie neonatal-onset cytopenia, autoinflammation, rash, and hemophagocytic lymphohistiocytosis (NOCARH). Pyrin inflammasome hyperactivation has been shown to contribute to disease pathophysiology. However, mortality of NOCARH patients remains high despite inflammasome-focused treatments. Here, we demonstrate in four NOCARH patients from three families that cell-intrinsic activation of type I interferon (IFN) is a previously unrecognized driver of autoinflammation in NOCARH. Our data show that aberrant innate immune activation is caused by sensing of cytosolic nucleic acids released from mitochondria, which exhibit disturbances in integrity and dynamics due to CDC42 dysfunction. In one of our patients, treatment with the Janus kinase inhibitor ruxolitinib led to complete remission, indicating that inhibition of type I IFN signaling may have an important role in the management of autoinflammation in patients with NOCARH.

Rapid and sustained response to JAK inhibition in a child with severe MDA5 + juvenile dermatomyositis

BackgroundJuvenile dermatomyositis (jDM) is the most common idiopathic inflammatory myopathy of childhood. Amyopathic or hypomyopathic courses have been described.Case presentationWe present the case of a 4-year-old patient with MDA5 antibody positive jDM and interstitial lung disease. In our patient, typical symptoms of jDM with classical skin lesions, arthritis, proximal muscle weakness, and ulcerative calcifications were observed. Due to the severity of the disease and the pulmonary changes, therapy with the Janus kinase (JAK) inhibitor ruxolitinib was added to the therapy with corticosteroids, intravenous immunoglobulins (IVIG) and hydroxychloroquine leading to a fast and sustained remission.ConclusionWhile there is growing evidence that JAK inhibition is a promising therapeutic option in jDM our case report shows that this approach may also be effective in MDA5-positive jDM with high risk features.

Variant STAT4 and Response to Ruxolitinib in an Autoinflammatory Syndrome

BackgroundDisabling pansclerotic morphea (DPM) is a rare systemic inflammatory disorder, characterized by poor wound healing, fibrosis, cytopenias, hypogammaglobulinemia, and squamous-cell carcinoma. The cause is unknown, and mortality is high.MethodsWe evaluated four patients from three unrelated families with an autosomal dominant pattern of inheritance of DPM. Genomic sequencing independently identified three heterozygous variants in a specific region of the gene that encodes signal transducer and activator of transcription 4 (STAT4). Primary skin fibroblast and cell-line assays were used to define the functional nature of the genetic defect. We also assayed gene expression using single-cell RNA sequencing of peripheral-blood mononuclear cells to identify inflammatory pathways that may be affected in DPM and that may respond to therapy.ResultsGenome sequencing revealed three novel heterozygous missense gain-of-function variants in STAT4. In vitro, primary skin fibroblasts showed enhanced interleukin-6 secretion, with impaired wound healing, contraction of the collagen matrix, and matrix secretion. Inhibition of Janus kinase (JAK)–STAT signaling with ruxolitinib led to improvement in the hyperinflammatory fibroblast phenotype in vitro and resolution of inflammatory markers and clinical symptoms in treated patients, without adverse effects. Single-cell RNA sequencing revealed expression patterns consistent with an immunodysregulatory phenotype that were appropriately modified through JAK inhibition.ConclusionsGain-of-function variants in STAT4 caused DPM in the families that we studied. The JAK inhibitor ruxolitinib attenuated the dermatologic and inflammatory phenotype in vitro and in the affected family members. (Funded by the American Academy of Allergy, Asthma, and Immunology Foundation and others.)

Serum proteomics hint at an early T-cell response and modulation of SARS-CoV-2-related pathogenic pathways in COVID-19-ARDS treated with Ruxolitinib.

Acute respiratory distress syndrome (ARDS) in corona virus disease 19 (COVID-19) is triggered by hyperinflammation, thus providing a rationale for immunosuppressive treatments. The Janus kinase inhibitor Ruxolitinib (Ruxo) has shown efficacy in severe and critical COVID-19. In this study, we hypothesized that Ruxo's mode of action in this condition is reflected by changes in the peripheral blood proteome. This study included 11 COVID-19 patients, who were treated at our center's Intensive Care Unit (ICU). All patients received standard-of-care treatment and n = 8 patients with ARDS received Ruxo in addition. Blood samples were collected before (day 0) and on days 1, 6, and 10 of Ruxo treatment or, respectively, ICU admission. Serum proteomes were analyzed by mass spectrometry (MS) and cytometric bead array. Linear modeling of MS data yielded 27 significantly differentially regulated proteins on day 1, 69 on day 6 and 72 on day 10. Only five factors (IGLV10-54, PSMB1, PGLYRP1, APOA5, WARS1) were regulated both concordantly and significantly over time. Overrepresentation analysis revealed biological processes involving T-cells only on day 1, while a humoral immune response and complement activation were detected at day 6 and day 10. Pathway enrichment analysis identified the NRF2-pathway early under Ruxo treatment and Network map of SARS-CoV-2 signaling and Statin inhibition of cholesterol production at later time points. Our results indicate that the mechanism of action of Ruxo in COVID-19-ARDS can be related to both known effects of this drug as a modulator of T-cells and the SARS-CoV-2-infection.

Development of warm autoimmune hemolytic anemia after initiation of Ruxolitinib in a patient with STAT1 gain-of-function mutation

IntroductionSTAT1 gain-of-function (GOF) disease is associated with chronic mucocutaneous candidiasis (CMC) and a broad spectrum of infectious, inflammatory, and vascular manifestations. The Janus Kinase inhibitor ruxolitinib has been used successfully for CMC and autoimmune phenomena. We describe a case of warm autoimmune hemolytic anemia (WAIHA) in a patient with STAT1 GOF disease after initiating ruxolitinib. Case reportA 36-year-old man with STAT1 c.850G>A (p.Glu284Lys) mutation presented with CMC as well as recurrent viral and bacterial infections, lymphadenopathy, enteritis, nodular regenerative hyperplasia (NRH) and splenomegaly. Immune workup confirmed a combined immunodeficiency with hypogammaglobulinemia and T-cell lymphopenia. Ruxolitinib was initiated at 5 mg twice daily (due to pre-existing thrombocytopenia) with up titration over 3 months to 20 mg twice daily. He improved with weight gain, increased energy, resolution of chronic anemia, and improved lymphadenopathy and splenomegaly on imaging. Serum CXCL9 only minimally decreased from 4660 pg/ml to 3990 pg/ml. Soon after reaching ruxolitinib 20 mg twice daily, he developed JC viremia, prompting dose reduction to 15 mg BID. Within two weeks, he developed a non-COVID upper respiratory tract infection followed by fatigue, shortness of breath with ambulation, and dark urine. Emergency evaluation revealed warm antibody positive hemolytic anemia with a hemoglobin of 5 g/dL, and worsened thrombocytopenia. He was treated with blood transfusions, pulse steroids, and high-dose IVIG with stabilization but continued hemolysis. Due to the JC viremia, there was concern to give rituximab with increased PML risk. Bone marrow showed trilineage hematopoiesis, a mild increase in megakaryocytes and RBC precursors, and a loss of B-cell progenitors with retention of mature B cells. His B and T lymphocyte numbers had increased since prior to ruxolitinib, with a predominance of Tfh1-cells (58.7% of total Tfh-cells). He was started on sirolimus with a slow taper of prednisone with continued stable hemoglobin and platelets, and resolution of hemolysis after 3 months. ConclusionTo our knowledge, this is the first case of a STAT1 GOF patient developing WAIHA while receiving ruxolitinib therapy. Treatment choices were complicated by the risks of PML. Sirolimus combined with ruxolitinib allowed wean of corticosteroid and subsequent resolution of hemolysis.

Janus kinase inhibitor ruxolitinib in combination with nilotinib and prednisone in patients with myelofibrosis (RuNiC study): A phase Ib, multicenter study.

This phase Ib, non-randomized, open-label study evaluates the safety and tolerability of ruxolitinib in combination with nilotinib and prednisone in patients with naïve or ruxolitinib-resistant myelofibrosis (MF). A total of 15 patients with primary or secondary MF received the study treatment; 13 patients had received prior ruxolitinib treatment (86.7%). Eight patients completed seven cycles (53.3%) and six patients completed twelve cycles of treatment (40%). All the patients experienced at least one adverse event (AE) during the study (the most common AEs were hyperglycemia, asthenia, and thrombocytopenia), and 14 patients registered at least one treatment-related AE (the most common treatment-related AEs were hyperglycemia (22.2%; three grade 3 cases). Five treatment-related serious AEs (SAEs) were reported in two patients (13.3%). No deaths were registered throughout the study. No dose-limiting toxicity was observed. Four out of fifteen (27%) patients experienced a 100% spleen size reduction at Cycle 7, and two additional patients achieved a>50% spleen size reduction, representing an overall response rate of 40% at Cycle 7. In conclusion, the tolerability of this combination was acceptable, and hyperglycemia was the most frequent treatment-related AE. Ruxolitinib in combination with nilotinib and prednisone showed relevant clinical activity in patients with MF. This trial was registered with EudraCT Number 2016-005214-21.

Paradoxical activation of chronic lymphocytic leukemia cells by ruxolitinib in vitro and in vivo.

Chronic lymphocytic leukemia (CLL) is characterized by an aberrant cytokine network that can support tumor growth by triggering janus kinase (JAK)/STAT pathways. Targeting cytokine-signaling should then be a rational therapeutic strategy but the JAK inhibitor ruxolitinib failed to control and seemingly accelerated the disease in clinical trials. The effect of ruxolitinib on primary human CLL cells was studied in vitro and in vivo. Ruxolitinib increased phosphorylation of IRAK4, an important toll-like receptor (TLR)- signaling intermediate, in circulating CLL cells in vitro. It also enhanced p38 and NFKB1 phosphorylation while lowering STAT3 phosphorylation in CLL cells activated with TLR-7/8 agonists and IL-2. Among the cytokines made by activated CLL cells, high levels of IL-10 contributed strongly to STAT3 phosphorylation and inhibited TLR7 activity. Ruxolitinib limited TLR-mediated IL10 transcription and markedly reduced IL-10 production in vitro. It also decreased blood levels of IL-10 while increasing TNFα along with phospho-p38 expression and gene sets associated with TLR-activation in CLL cells in vivo. The bruton's tyrosine kinase inhibitor ibrutinib decreased IL-10 production in vitro but, in contrast to ruxolitinib, blocked initial IL10 transcription induced by TLR-signaling in vitro, decreased TNFα production, and deactivates CLL cells in vivo. These findings suggest the possible benefits of inhibiting growth factors with JAK inhibitors in CLL are outweighed by negative effects on potential tumor suppressors such as IL-10 that allow unrestrained activation of NFκB by drivers such as TLRs. Specific inhibition of growth-promoting cytokines with blocking antibodies or infusing suppressive cytokines like IL-10 might be better strategies to manipulate cytokines in CLL.

Keratinocytes and immune cells in the epidermis are key drivers of inflammation in hidradenitis suppurativa providing a rationale for novel topical therapies

Hidradenitis suppurativa (HS) is a debilitating inflammatory skin disease characterized by painful nodules, drainage and scarring in skin folds. Injectable adalimumab is the only drug approved by the US Food and Drug Administration for the treatment of HS. Although systemic Janus kinase (JAK) inhibitors show promise, serious side-effects have been reported. There are no highly effective topical treatments for HS; furthermore, the contribution of epidermal keratinocytes to the intense inflammation has largely been unexplored. We investigated the role of keratinocytes and epidermal immune cells in HS inflammation at all Hurley stages of disease severity. We aimed to determine whether ruxolitinib can mitigate inflammation from keratinocytes and to develop a better understanding of how topical therapeutics might benefit patients with HS. We used skin samples from 87 patients with HS (Hurley stages I-III) and 39 healthy controls to compare keratinocyte- and immune cell-driven epidermal inflammation, in addition to the response of lesional HS keratinocytes to treatment with interferon (IFN)-γ and ruxolitinib. We used haematoxylin and eosin staining, immunohistochemistry, immunoblotting and quantitative reverse-transcription polymerase chain reaction assessments in whole skin, isolated epidermis, and cultured keratinocytes from healthy controls and both nonlesional and lesional HS skin to identify and define epidermal and keratinocyte-mediated inflammation in HS and how this may be targeted by therapeutics. HS lesional keratinocytes autonomously secreted high levels of chemokines, such as CCL2, CCL3 and CXCL3, which recruited neutrophils, CD8 T cells, and natural killer cells to the epidermis. Keratinocytes were the dominant source of tumour necrosis factor-α and interleukin (IL)-6 in HS lesions with little to no contribution from underlying dermal immune cells. In the presence of IFN-γ, which is dependent on immune cell infiltrate in vivo, keratinocytes expressed increased levels of additional cytokines including IL-1β, IL-12, IL-23 and IL-36γ. The JAK inhibitor ruxolitinib mitigated the expression of inflammatory cytokines and chemokines in HS lesional keratinocytes, thus providing a rationale for future study as a topical treatment for HS. This study demonstrates that keratinocytes actively recruit immune cells to HS epidermis and interactions between these cells drive a broad inflammatory profile in HS epidermis. Targeting epidermal inflammation in HS with novel topical formulations may be highly efficacious with reduced systemic side-effects.

Pelabresib (CPI-0610) As Add-on to Ruxolitinib in Myelofibrosis: Durability of Response and Safety Beyond Week 24 in the Phase 2 MANIFEST Study

Background: Myelofibrosis (MF) is largely characterized by bone marrow (BM) fibrosis, splenomegaly and cytopenias. Progressive BM fibrosis results from aberrant megakaryopoiesis and proinflammatory cytokine expression, two processes that are tightly regulated by bromodomain and extraterminal domain (BET) protein-mediated expression of genes (eg NF-κB target genes, MYC and BCL-2) and often lead to myeloproliferation and cytopenias. Although the current standard of care for MF is treatment with the Janus kinase inhibitor (JAKi) ruxolitinib (RUX), many patients (pts) experience a suboptimal response to RUX monotherapy or must discontinue treatment due to cytopenias and therefore there is a significant unmet need for new therapies in this population. Pelabresib (CPI-0610; PELA) is an oral, small-molecule, investigational BET inhibitor that downregulates NF-κB signaling and other relevant genes involved in MF disease pathways (Mascarenhas J, et al. HemaSphere 2022;6:99-100). Aims: In the ongoing, open-label Phase 2 MANIFEST study (NCT02158858), PELA is under investigation as monotherapy and in combination with RUX in pts with MF. In Arm 2 of MANIFEST, pts with suboptimal/lost response to RUX are treated with PELA as 'add-on’ to RUX. In this abstract we will discuss results from the September 2021 data cut; updated data with longer follow-up on efficacy (≥35% reduction in spleen volume from baseline [BL; SVR35], ≥50% total symptom score reduction from BL [TSS50], duration of response and BM fibrosis improvement) and safety data from the planned July 2022 data cut will be presented. Methods: Pts in Arm 2 are stratified as transfusion dependent (TD; Arm 2A) and nontransfusion dependent (non-TD; Arm 2B). The primary endpoints are conversion from TD to transfusion independence (TI) in Arm 2A (TD cohort) and SVR35 at Week (Wk) 24 for Arm 2B (non-TD cohort). The secondary endpoints include TSS50 per MF Symptom Assessment Form v4.0 at Wk 24 and SVR35 at Wk 24 in Arm 2A (TD cohort). BM biopsies to assess BM fibrosis, durability of responses and safety data are evaluated. Data reported here are from the September 2021 data cut. Results: At Wk 24 in Arm 2 (N=86), 20% (16/81) of pts achieved SVR35 (Figures 1 and 2); 17% for Arm 2A (TD cohort) and 26% for Arm 2B (non-TD cohort). SVR35 at any time was achieved by 30% (24/81) of pts. At Wk 24, 27% (22/81) pts achieved ≥25% reduction in spleen volume from BL (SVR25); 26% (14/54) pts in Arm 2A (TD cohort) and 30% (8/27) pts in Arm 2B (non-TD cohort). Median spleen volume reduction for the full Arm 2 cohort was -18% at Wk 24. Durable (up to Wk 60) spleen volume reductions were observed as depicted in mean spleen volume change over time, and spleen volume reduction deepened over time (Figure 1). Twenty percent (16/80) pts had SVR35 response at Wk 48. In Arm 2A (TD cohort), the TD to TI rate was 16% (6/38). TSS50 at Wk 24 was 37% (30/81); 36% for Arm 2A (TD cohort) and 39% for Arm 2B (non-TD cohort). A total of 54% (46/86) of pts achieved TSS50 at any time. Median total symptom score reduction was -47% at Wk 24. As of data cut off, the median follow-up time was 24.4 (23.0-30.7) months and median treatment duration was 14.0 (8.4-20.6) months. After 24 wks of treatment, BM fibrosis improvement by ≥1 grade was achieved in 26% of evaluable pts by central pathology review; 50% of pts maintained the improvement at the next available assessment or longer. A total of 39% of pts achieved ≥1 grade improvement at any time (best response). The two most common hematologic treatment-emergent adverse events (TEAEs) of any grade were thrombocytopenia, reported in 52% (Grade ≥ 3: 33%) pts, and anemia, reported in 27% (Grade ≥ 3: 19%) pts. Low-grade gastrointestinal TEAEs and respiratory infections were observed but rarely a reason for treatment discontinuation. A total of 20 pts (23%) reported TEAEs that led to PELA discontinuation. Serious adverse events reported in ≥3 pts were anemia (6 pts), respiratory tract infections (4 pts) and urinary tract infections (3 pts). Conclusions: Based on these preliminary Phase 2 data, PELA as 'add-on’ to RUX in pts with a suboptimal/lost response to RUX monotherapy resulted in durable splenic and symptom responses, deepening of spleen responses over time, and was generally well tolerated. Additionally, improvement in BM fibrosis, as a marker of disease modification, was observed in 39% of treated pts. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Pelabresib (CPI-0610) Combined with Ruxolitinib for JAK Inhibitor Treatment-Naïve Patients with Myelofibrosis: Durability of Response and Safety Beyond Week 24

Background: Myelofibrosis (MF) is characterized by progressive bone marrow (BM) fibrosis, splenomegaly and cytopenias resulting from aberrant megakaryopoiesis and proinflammatory cytokine expression. These processes are heavily regulated by bromodomain and extraterminal domain (BET) protein-mediated gene expression (eg NF-κB target genes, MYC and BCL-2) and lead to myeloproliferation and cytopenias. The current standard of care for patients (pts) with MF is the Janus kinase inhibitor (JAKi) ruxolitinib (RUX); however, the depth and durability of responses, along with the percentage of pts that achieve ≥35% spleen volume reduction from baseline (BL; SVR35) and ≥50% total symptom score reduction (TSS) from BL (TSS50) with RUX monotherapy are limited. Pelabresib (CPI-0610; PELA) is an oral, small-molecule, investigational BET inhibitor that downregulates NF-κB signaling and other relevant genes involved in MF disease pathways (Mascarenhas J, et al. HemaSphere 2022;6:99-100). In the ongoing Phase 2 MANIFEST study (NCT02158858), PELA is under investigation as monotherapy and in combination with RUX in pts with MF. Here, we present results from Arm 3 of MANIFEST (in which JAKi-naïve pts with MF receive PELA in combination with RUX). Aims: The primary endpoint of MANIFEST Arm 3 is SVR35 after 24 weeks (wks) of treatment. Secondary endpoints include TSS50, duration of splenic response, pharmacokinetics and safety. Exploratory endpoints include transfusion independence and changes from BL in BM fibrosis. In this abstract we will discuss results from the September 2021 data cut; longer-term data from the July 2022 data cut will be presented. Methods: Spleen volume was assessed by computed tomography or magnetic resonance imaging every 12 wks; TSS per Myelofibrosis Symptom Assessment Form v4.0; and BM fibrosis by biopsies at Wk 24 and Wk 48. Duration of splenic response and safety data are also evaluated. Data presented are from the September 2021 data cut; a more mature data set will be presented at the conference. Results: Eighty-four pts received ≥1 dose of PELA and RUX. Median age was 68 years (range 37-85); 24%, 61% and 16% had Dynamic International Prognostic Scoring System intermediate-1, intermediate-2 or high risk, respectively. Pts who did not reach Wk 24 were counted as nonresponders. At Wk 24 and Wk 48, 68% (57/84) and 60% (47/79) of pts, respectively, achieved SVR35. SVR35 at any time was achieved by 80% pts (67/84), and 87% (58/67) pts with SVR35 maintained response at the time of data cutoff. Median spleen volume change was -50% (range -84.4% to 27.9%) at Wk 24. Median time to SVR35 response was 12 wks (first on-treatment assessment of splenic response); durable spleen volume reductions were observed as depicted in mean spleen volume change over time in Figure 1. TSS50 was achieved by 56% (46/82) pts at Wk 24 and 43% (34/79) at Wk 48. TSS50 at any time was achieved by 81% pts (68/84). The median change in TSS was −59% (range −100% to 225%) at Wk 24. Mean TSS change over time is shown in Figure 2, indicating sustained reduction in symptom burden. Median follow up for Arm 3 was 21.8 (range 21.2-22.5) months; median treatment duration was not reached as of data cutoff. BM fibrosis improved by ≥1 grade in 28% (16/57) of evaluable pts at Wk 24 as assessed by central pathology review; 56% maintained the improvement at the next available assessment (Wk 48 or beyond) or longer; and 40% achieved ≥1 grade improvement at any time (best response). The most common hematologic treatment-emergent adverse event (TEAE) of any grade was thrombocytopenia, reported in 52% (Grade ≥3: 12%) of pts. Anemia was reported in 42% (Grade ≥3: 34%). Serious adverse events reported in ≥2 pts were respiratory tract infections (6 pts), pyrexia (3 pts) and anemia, multiorgan failure, fall and pelvic fracture (2 pts each). TEAEs that led to PELA discontinuation occurred in 7 pts (8%). Updated data with longer follow-up, including durability of splenic response and safety data from a more mature data set, will be available for presentation at the conference. Conclusions: The combination of PELA and RUX in JAKi-naïve pts with MF showed durable improvements in spleen volume, total symptom score and BM fibrosis, and was generally well tolerated. The randomized, double-blind, active-controlled Phase 3 MANIFEST-2 study is open for enrollment and evaluating the safety and efficacy of PELA in combination with RUX in JAKi treatment-naïve pts with MF (NCT04603495). Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

The Combination of Navitoclax and Ruxolitinib in JAK Inhibitor-Naïve Patients with Myelofibrosis Mediates Responses Suggestive of Disease Modification

Background: Myelofibrosis (MF) is a myeloproliferative neoplasm associated with splenomegaly, high symptom burden, bone marrow fibrosis (BMF), and poor prognosis. The Janus kinase inhibitor (JAKi) ruxolitinib is the current standard of care for patients with MF. It improves splenomegaly and disease symptoms with limited impact on disease biology, highlighting an unmet medical need in MF. Driver mutations of JAK2, CALR, and MPL are key to the pathogenesis of MF. Reduction in variant allele frequency (VAF) of driver mutations and reversal of BMF are suggestive of disease modification (Pemmaraju, Cancer, 2022). Additionally, mutations in ASXL1, EZH2, SRSF2, IDH1/2, and U2AF1 p.Q157 are classified as high molecular risk (HMR) mutations associated with a worse prognosis (Arber et al., Blood, 2016). We previously demonstrated evidence of disease modification independent of HMR mutations by adding navitoclax to ruxolitinib in patients with suboptimal responses to ruxolitinib monotherapy (Pemmaraju, Lancet Oncology, 2022). Herein, we investigated whether the type of MF and risk (e.g., age, Dynamic International Prognostic Scoring System [DIPSS], and HMR) correlated with clinical outcomes and responses suggestive of disease modification (e.g., VAF reduction and improvement in BMF) among JAKi treatment-naïve patients with MF treated with the combination of navitoclax and ruxolitinib. Methods: Cohort-3 of the phase-2 multicenter REFINE study (NCT03222609) enrolled JAKi treatment-naïve patients with MF. Enrolled patients had primary or secondary MF with splenomegaly (DIPSS ≥ Intermediate-1) and did not receive prior JAK-2 therapy or bromodomain and extra terminal motif (BET) inhibitors. Patients initiated navitoclax at 100 mg QD or 200 mg QD if baseline platelet count was ≤ 150 × 109/L or > 150 × 109/L, respectively. Ruxolitinib was given BID with starting dose based on baseline platelet count per local label. The primary endpoint was spleen volume reduction of ≥ 35% (SVR35) from baseline at week 24, assessed by MRI conducted by central review. Key secondary and exploratory endpoints evaluated in this analysis were a reduction in BMF obtained from BM biopsies by local evaluation and a reduction in VAF for the driver gene mutations (JAK2V617, CALR, or MPL), respectively. Driver gene VAF and HMR mutations were determined in whole blood with the 50-gene Focus Myeloid next-generation sequencing panel (Interspace Pharma Solutions, Morrisville, NC, USA). Results: As of Feb 07, 2022, all enrolled patients (N = 32) treated with navitoclax and ruxolitinib were evaluable for biomarker analysis. The median duration of follow-up was 6.1 months (range, 1.9 – 18.6); median age was 69 years (range, 44 – 83), and median spleen volume was 1889.08 cm3 (range, 645.6 – 7339.6). At baseline, 22 (69%) patients had JAK2, 6 (19%) had CALR, and 3 (9%) had MPL mutations. One (3%) patient was triple negative. Nineteen (59%) patients had HMR mutations. SVR35 at week 24 was observed in all subgroups known to confer poor prognosis, including age (≥75 years, 50% [n = 4/8]), high DIPSS score (Intermediate-2, 63% [n = 12/19]; high, 33% [n = 1/3]), and HMR mutations (47% [n = 9/19]; Figure). BMF grade improvement was evaluable in 26/32 (81%) patients, of which 9/26 (35%) achieved ≥ 1-grade improvement at any time during treatment with a median time-to-improvement of 12.3 weeks (range, 12.1 – 24.1). Complete resolution of BMF was observed in 2/9 (22%) patients. The baseline BMF grades of these patients were 2 and 3. BMF ≥ 1-grade improvement was achieved by 7/13 (54%) patients with HMR mutations and 2/13 (15%) without HMR mutations. Reduction in driver gene JAK2V617 mutation VAF > 20% from baseline at week 12 or 24 was observed in 14/28 (50%) patients, and 5/14 (36%) patients achieved > 50% VAF reduction from baseline. There were no differences in > 20% VAF reductions from baseline to week 12 or 24 between those with or without HMR mutations (7/15 [47%] versus 7/13 [54%], respectively). Conclusions: Among JAKi treatment-naïve patients with MF, the combination of navitoclax and ruxolitinib reduced splenomegaly in several high-risk groups known to confer poor prognosis. Reductions in BMF and VAF were independent of HMR mutations. The reduction in BMF and VAF for the driver mutation JAK2V617 is encouraging and suggestive of evidence of disease modification with the combination of navitoclax and ruxolitinib. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Possibilities of targeted therapy for myelofibrosis: Moscow experience

Background. For many years the primary aim of treatment strategy for ph-negative myeloproliferative neoplasms has been to restrain disease progression, with lasting relief and management of symptoms to improve patients’ quality of life. Generally, this did not lead to a significant increase in life expectancy with primary myelofibrosis and didn’t decrease the risk of fibrosis in patients with polycythemia vera and essential thrombocythemia. To date a new class of targeted drugs has been developed, it is JAK2 inhibitors with pathogenetic effects. The results of clinical trials showed the high efficacy of the first registered drug of this its kind – ruxolitinib – that includes a faster reduction in the symptoms of tumor intoxication and in symptoms associated with the development of splenomegaly and increase in the overall survival rates. It is known that the data obtained during clinical trials of medicines may differ from the results obtained in routine clinical practice. In actual practice drugs are used in a much wider heterogeneous population of patients, less limited first of all by age and comorbid characteristics. It is possible to analyze cohorts of patients including a larger number of clinical cases with a longer follow-up period. In this regard of great interest is the actual clinical experience of long-term use of ruxolitinib in patients whose set is limited only by clinical contraindications for prescribing the drug.Aim. To present our own actual experience of targeted therapy of myelofibrosis and compare the results obtained with the data of clinical trials.Materials and methods. Our analysis includes data from 141 patients (67 (47.5 %) men and 74 (52.5 %) women) in a chronic phase myelofibrosis. All patients received ruxolitinib. Of these, 109 (69 %) patients had primary myelofibrosis, 26 (16 %) – postpolycythemia myelofibrosis, 6 (4 %) – postessential thrombocythemia myelofibrosis. The median age at the start of therapy was 62 (18–84) years. The median disease duration before ruxolitinib was prescribed – 79 (1–401) months. According to the dIpSS (dynamic International prognostic Scoring System) criteria, 13 % of patients were assigned to the low risk group, 38 % – to the intermediate-1, 36 % – to the intermediate-2, 13 % – to the high risk group. Most patients (52 %) had grade 3 bone marrow fibrosis.Results. The median duration of treatment was 18 (range from 1 to 115) months. Symptoms of intoxication were relieved 74 (81 %) of 91 patients, the spleen size decreased in 81 % of patients (the spleen size returned to normal in 25 % of patients). The increase in the median hemoglobin level was 15 %. The proportion of patients requiring blood transfusion decreased by 4 times (from 39 to 9 %). Mean platelet levels normalized in most patients with baseline high and low platelet levels. A complete clinical and hematological response was achieved in 16 % (n = 23) of cases, a partial response – in 26 % (n = 37) of cases, clinical improvement – in 21 % (n = 30), disease stabilization – in 33 % (n = 46) of cases. No response was received in 1 (1 %) patient and in 3 (3 %) cases there was progression of the disease. At the time of analysis, 81 (57 %) of 141 patients were continuing the ruxolitinib treatment. The fatal outcome in 33 (22 %) patients was associated with concomitant diseases, among which 20 (14 %) died from proven COvId-19 infection. Overall survival: 1-year 81 %, 2-year 73 %, 5-year 50 %. Overall survival excluding deaths due to COvId-19: 1-year 92 %, 2-year 85 %, 5-year 70 %. Massive splenomegaly and a high degree of fibrosis were unfavorable predictors of prognosis of overall survival.Conclusion. Target therapy with Janus kinase inhibitor ruxolitinib has demonstrated high efficacy in patients with myelofibrosis in routine clinical practice. The most rapid effect ruxolitinib had on the spleen size and the symptoms of intoxication. Tolerability of ruxolitinib therapy was generally satisfactory. The overall and progression-free survival rates in patients with myelofibrosis, receiving ruxolitinib in the clinical setting was consistent with the results of international multicenter clinical trials.

S192: SINGLE-CELL RNA PROFILING OF MYELOFIBROSIS PATIENTS REVEALS PELABRESIB-INDUCED DECREASE OF MEGAKARYOCYTIC PROGENITORS AND NORMALIZATION OF CD4+ T CELLS IN PERIPHERAL BLOOD

Background: Abnormal differentiation of the megakaryocytic (MK) lineage in conjunction with overproduction of proinflammatory cytokines (Ck), resulting in bone marrow fibrosis, anemia, extramedullary hematopoiesis and often hepatosplenomegaly, are the main biological and clinical characteristics of myelofibrosis (MF). Bromodomain and extraterminal domain (BET) proteins play a key role in the regulation of neoplastic myeloproliferation and proinflammatory Ck production. Pelabresib (CPI-0610) is a potent, selective BET inhibitor under investigation in MF patients (pts) as monotherapy and in combination with the Janus kinase inhibitor (JAKi) ruxolitinib (RUX) in the ongoing MANIFEST Phase 2 study (NCT02158858). Arm 1: pelabresib as monotherapy in RUX-intolerant, ineligible or refractory MF pts; Arm 2: pelabresib in combination with RUX as an ‘add-on’ in MF pts with suboptimal response to RUX; Arm 3: pelabresib combination therapy with RUX in JAKi-naïve MF pts. Pelabresib as monotherapy and in combination with RUX improved spleen volume reduction, symptoms and hemoglobin levels (Talpaz M, ASH 2020). The effects of pelabresib on hematopoietic stem/progenitor cells (HSPCs) and immune cell populations in MF pts are presented here. Aims: We aimed to characterize the cellular composition and transcriptional alterations occurring in peripheral blood (PB) obtained from MF pts enrolled in the MANIFEST trial. Methods: We performed single-cell RNA sequencing on 234,904 CD34+ HSPCs and 135,970 CD34- mature PB cells (Figure). Cells were obtained from a random pool of 20 pts (Arm 1 n=5, Arm 2 n=8, Arm 3 n=7), which included a baseline sample (BL) and samples collected during treatment (range: C3 through C12) for each pt. Mobilized PB cells from healthy donors (HD) were used as a control (n=11). Results: Analysis of CD34+ HSPCs at BL demonstrated a statistically significant increase of MK, neutrophilic and erythroid progenitors in MF pts compared with HDs and decreased numbers of myeloid and B cell lineage progenitors. Pelabresib as monotherapy and in combination with RUX led to a significant reduction of MK-, neutrophilic and erythroid progenitors as compared with BL in all pts analyzed. Analysis of CD34- cells from MF pts identified a significantly lower proportion of CD4+ T cells and increased numbers of erythroid cells at BL compared with HD. Individual pts also exhibited reduction in natural killer cells and CD16+ monocytes as well as elevated MK lineage cells. Pelabresib as monotherapy and in combination with RUX increased the proportion of CD4+ T cells, and more importantly, reduced MK lineage cells compared with BL in both treatment-naïve and RUX relapsed/refractory (r/r) pts. In MF pts at BL, a larger spleen volume was observed in pts with lower numbers of CD4+ T cells and increased numbers of MK- and myeloid CSF3R+ cells. Updated results of the cell composition analysis and transcriptional reprogramming during pelabresib treatment, as well as correlation with effects on cytokine plasma levels and clinical efficacy data, will be presented. Image:Summary/Conclusion: The single-cell profiling of a subset of MF pts enrolled in the MANIFEST study suggests that pelabresib alone and in combination with RUX induces an improvement of the myeloid-lymphoid imbalance in both JAKi-naïve and r/r MF pts. The observed effects of pelabresib on HSPCs from MF pts confirm the ex vivo activity on erythroid and MK differentiation of stem cells (Keller P, EHA 2021; Verstovsek S, ASH 2021) and implies a potential disease-modifying effect warranting further investigation.

The JAK inhibitor ruxolitinib abrogates immune hepatitis instigated by concanavalin A in mice

Therapeutics that impair the innate immune responses of the liver during the inflammatory cytokine storm like that occurring in COVID-19 are greatly needed. Much interest is currently directed toward Janus kinase (JAK) inhibitors as potential candidates to mitigate this life-threatening complication. Accordingly, this study investigated the influence of the novel JAK inhibitor ruxolitinib (RXB) on concanavalin A (Con A)-induced hepatitis and systemic hyperinflammation in mice to simulate the context occurring in COVID-19 patients. Mice were orally treated with RXB (75 and 150 mg/kg) 2 h prior to the intravenous administration of Con A (20 mg/kg) for a period of 12 h. The results showed that RXB pretreatments were efficient in abrogating Con A-instigated hepatocellular injury (ALT, AST, LDH), necrosis (histopathology), apoptosis (cleaved caspase-3) and nuclear proliferation due to damage (PCNA). The protective mechanism of RXB were attributed to i) prevention of Con A-enhanced hepatic production and systemic release of the proinflammatory cytokines TNF-α, IFN-γ and IL-17A, which coincided with decreasing infiltration of immune cells (monocytes, neutrophils), ii) reducing Con A-induced hepatic overexpression of IL-1β and CD98 alongside NF-κB activation, and iii) lessening Con A-induced consumption of GSH and GSH peroxidase and generation of oxidative stress products (MDA, 4-HNE, NOx) in the liver. In summary, JAK inhibition by RXB led to eminent protection of the liver against Con A-deleterious manifestations primarily via curbing the inflammatory cytokine storm driven by TNF-α, IFN-γ and IL-17A.

Real-world survival of US patients with intermediate- to high-risk myelofibrosis: impact of ruxolitinib approval

The Janus kinase inhibitor ruxolitinib is approved for the treatment of myelofibrosis (MF) and improved overall survival (OS) versus control therapy in the phase 3 COMFORT trials. The aim of this retrospective analysis was to examine the real-world impact of ruxolitinib on OS in patients with MF. The US Medicare Fee-for-Service claims database (parts A/B/D) was used to identify patients with ≥ 1 inpatient or ≥ 2 outpatient claims with an MF diagnosis (January 2010–December 2017). Eligible patients with MF were ≥ 65 years old (intermediate-1 or higher risk based on age). Patients were divided into 3 groups based on ruxolitinib approval status at diagnosis and ruxolitinib exposure: (1) preapproval, ruxolitinib-unexposed; (2) post-approval, ruxolitinib-unexposed; and (3) post-approval, ruxolitinib-exposed. In total, 1677 patients with MF were included (preapproval [all ruxolitinib-unexposed], n = 278; post-approval, n = 1399 [ruxolitinib-unexposed, n = 1127; ruxolitinib-exposed, n = 272]). Overall, median age was 78 years, and 39.8% were male. Among patients with valid death dates (preapproval, n = 119 [42.8%]; post-approval, ruxolitinib-unexposed, n = 382 [33.9%]; post-approval ruxolitinib-exposed, n = 54 [19.9%]), 1-year survival rates were 55.6%, 72.5%, and 82.3%, and median OS was 13.2 months, 44.4 months, and not reached, respectively. Risk of mortality was significantly lower post- versus preapproval regardless of exposure to ruxolitinib (ruxolitinib-unexposed: adjusted hazard ratio [HR], 0.67; ruxolitinib-exposed: adjusted HR, 0.36; P < 0.001 for both); post-approval, mortality risk was significantly lower in ruxolitinib-exposed versus ruxolitinib-unexposed patients (adjusted HR, 0.61; P = 0.002). Findings from this study complement clinical data of ruxolitinib in MF by demonstrating a survival benefit in a real-world setting.