P1, N=20, Not yet recruiting, University of Kansas Medical Center

P1, N=24, Recruiting, Fox Chase Cancer Center | Not yet recruiting --> Recruiting

P1/2, N=206, Recruiting, Incyte Corporation | N=100 --> 206 | Trial completion date: Apr 2024 --> Jun 2026 | Trial primary completion date: Apr 2024 --> Nov 2025

Momelotinib-approved for treatment of myelofibrosis in adults with anemia-and its major active metabolite, M21, were assessed as drug-drug interaction (DDI) victims with a strong cytochrome P450 (CYP) 3A4 inhibitor (multiple-dose ritonavir), an organic anion transporting polypeptide (OATP) 1B1/1B3 inhibitor (single-dose rifampin), and a strong CYP3A4 inducer (multiple-dose rifampin). Momelotinib DDI perpetrator potential (multiple-dose) was evaluated with CYP3A4 and breast cancer resistance protein (BCRP) substrates (midazolam and rosuvastatin, respectively)...Safety findings were mild in this short-term study in healthy volunteers. This analysis suggests that momelotinib interactions with OATP1B1/1B3 inhibitors and BCRP substrates may warrant monitoring for adverse reactions or dose adjustments.

Recent years have seen the emergence of novel therapeutic agents, notably ruxolitinib and fedratinib, which target the Janus kinases (JAK) pathway. Due to its mechanism of action, MMB represents a valuable therapeutic option in MF, addressing the clinical challenge of anemia and potentially improving outcomes for patients with hematologic malignancies. Ongoing research explores MMB's potential in acute myeloid leukemia and combination therapies.

No abstract available

P2, N=25, Recruiting, University of Washington | Trial completion date: Nov 2024 --> Nov 2026 | Trial primary completion date: Nov 2024 --> Nov 2026

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.

In this work, we explored novel scaffold modifications of M4K2009, a 3,5-diphenylpyridine ALK2 inhibitor previously reported by our group...Notably, M4K2304 and M4K2306 exhibit exceptional selectivity for ALK2 over ALK5, surpassing the reference compound. Preliminary studies on their in vivo pharmacokinetics, including blood-brain barrier penetration, revealed that these constrained scaffolds have favorable exposure and do open a novel chemical space for further optimization and future evaluation in orthotopic models of DIPG.

P1/2, N=160, Not yet recruiting, National Cancer Institute (NCI)

Finally, pacritinib suppressed KSHV viral IL-6-induced human IL-6 and IL-10 production in peripheral blood mononuclear cells, which may model an important step in KSHV-MCD pathogenesis. These results suggest that pacritinib warrants testing for the treatment of KSHV-MCD and PEL.

Combining ADCT-602 + pacritinib was beneficial in ADCT-602-resistant cells. Chidamide increased CD22 expression on B-cell tumor surfaces, increasing ADCT-602 activity. These data support clinical testing of ADCT-602 in R/R B-ALL (NCT03698552) and CD22-positive hematological cancers.

P1, N=60, Completed, CTI BioPharma | Active, not recruiting --> Completed

P2, N=6, Active, not recruiting, Medical College of Wisconsin | Recruiting --> Active, not recruiting

Here we apply our experiences in the phase III trials of momelotinib, a JAK1/JAK2/ACVR1 inhibitor and the first therapy indicated by the US FDA for myelofibrosis patients with anemia, to highlight how application of different criteria impacts the anemia-related benefits reported for any potential treatment in myelofibrosis. We advocate for a convention of a new expert consensus panel to bring consistency and transparency to the definition of anemia-related response in myelofibrosis.

P1/2, N=20, Not yet recruiting, M.D. Anderson Cancer Center

P1, N=24, Not yet recruiting, Fox Chase Cancer Center

P2, N=60, Recruiting, Incyte Corporation | Trial completion date: Dec 2024 --> Apr 2028 | Trial primary completion date: Dec 2023 --> Apr 2025

P1/2, N=22, Active, not recruiting, Incyte Corporation | Recruiting --> Active, not recruiting | N=80 --> 22

The primary objective of treatment in myelofibrosis (MF) is prolongation of life, which is currently accomplished only by allogeneic hematopoietic stem cell transplantation (AHSCT). Pacritinib and fedratinib provide alternative options in the presence of severe thrombocytopenia or ruxolitinib-resistance/intolerance, respectively. Splenectomy remains a viable option for drug-resistant symptomatic splenomegaly and cytopenia.

P1/2, N=26, Not yet recruiting, Douglas Tremblay

Background: Prior to the approval of ropeginterferon alfa-2b-njft (ropeginterferon) in November 2021, the alternatives to hydroxyurea for the treatment of polycythemia vera (PV) included Janus Kinase inhibitors (JAKi) and older versions of recombinant interferon-alpha (rIFNα). This study examined FAERS reports to detect disproportional reporting odds of drug-associated AEs severity and SOCs in four PV treatments: ropeginterferon, ruxolitinib, interferon alfa-2a, and pacritinib. Ropeginterferon had a significant ROR for non-serious AEs. Peginterferon alfa-2a demonstrated a significant ROR for SAEs.

Reductions in transfusion dependence and transfusion visits for MMB vs RUX were associated with projected healthcare system savings in transfusion costs and transfusion-related time burden in JAK inhibitor–naive pts with MF, including in subgroup analyses of pts aged ≥65 years.

P2, N=0, Withdrawn, Keros Therapeutics, Inc. | N=20 --> 0 | Recruiting --> Withdrawn

Treatment with TP-0184 or in combination with BCL2 inhibitor, venetoclax dramatically inhibited leukemia growth in FLT3-mutated AML cell lines and patient-derived xenograft models in a dose-dependent manner. These findings suggest that ACVR1 is a novel biomarker and plays a role in AML resistance to FLT3 inhibitors and that FLT3/ACVR1 dual inhibitor TP-0184 is a novel potential therapeutic tool for AML with FLT3 mutations.

In September 2023, momelotinib was approved in the USA for the treatment of intermediate or high-risk MF, including primary MF or secondary MF &lsqb;post-polycythemia vera (PV) and post-essential thrombocythemia (ET)], in adults with anemia. This article summarizes the milestones in the development of momelotinib leading to this first approval for MF.

P1/2, N=50, Recruiting, National Cancer Institute (NCI) | Trial completion date: Nov 2023 --> Nov 2024 | Trial primary completion date: Nov 2023 --> Nov 2024

Interestingly, pacritinib exhibited synergistic effects when combined with temsirolimus and sunitinib, but antagonistic effects when combined with doxorubicin, in a panel of RCC cell lines. Mechanistic studies indicated that the inhibition of JAK2, but not IRAK, was the main contributor to the anti-RCC activity of pacritinib. Our study is the first to demonstrate that pacritinib shows promise as a treatment option for RCC and underscores the therapeutic potential of targeting the JAK2/STAT signalling pathway in RCC.

Post hoc analyses herein evaluated the efficacy and safety of momelotinib in patients with MF and thrombocytopenia (platelet counts <100 × 10/L) from randomized phase 3 studies: MOMENTUM (momelotinib versus danazol; JAK inhibitor experienced); SIMPLIFY-1 (momelotinib versus ruxolitinib; JAK inhibitor naïve); and SIMPLIFY-2 (momelotinib versus best available therapy; JAK inhibitor experienced); these studies were not statistically powered to assess differences in thrombocytopenic subgroups, and these analyses are descriptive. The safety profile of momelotinib in thrombocytopenic patients was also consistent with the overall study population. In summary, momelotinib represents a safe and effective treatment option for patients with MF and moderate-to-severe thrombocytopenia.

Thrombocytopenia is both prognostic of poor outcomes and predictive of treatment intolerance with the JAK1/2 inhibitor ruxolitinib, which exacerbates cytopenias. Of 117 patients randomized to pacritinib (75 from PERSIST-2, 42 from PAC203), 16% (n=19) experienced HI-P on study (as defined in methods). Additionally, 14 of the 19 HI-P patients had sustained platelet improvement over ≥12 weeks). By contrast, only 5% (4/77) of patients on BAT achieved HI-P response prior to end of study treatment.

Reductions in transfusion dependence and transfusion visits for MMB vs RUX were associated with projected healthcare system savings in transfusion costs and transfusion-related time burden in JAK inhibitor–naive pts with MF, including in subgroup analyses of pts aged ≥65 years.

FDA-approved JAKi for the treatment of MF include ruxolitinib, fedratinib, and pacritinib. CALR-1 mutation is the most important risk factor for both drug survival and longevity without AHSCT, in momelotinib-treated patients with MF. Such information might help identify MF patients who might benefit from treatment with momelotinib and in whom AHSCT might be deferred or not.

In cytopenic MF patients from PERSIST-2, TI-R on pacritinib was associated with BMF improvement. Though these results are based on a small sample size, they contrast with recent data suggesting no correlation between BMF reduction and TI-R on the JAK1/2 inhibitors momelotinib and ruxolitinib (Oh ST, et al. Blood 2022; 140 (Supp 1):821-23).

SIMPLIFY-1 included pts with JAK inhibitor–naive MF randomized (1:1) to receive MMB or ruxolitinib (RUX). In MOMENTUM, pts with symptomatic (Myelofibrosis Symptom Assessment Form Total Symptom Score ≥10), anemic (hemoglobin <10 g/dL), JAK inhibitor–experienced MF were randomized (2:1) to receive MMB or danazol (DAN)... These data demonstrate that MMB was associated with better maintenance of RBC transfusion intensity and zero RBC transfusion status vs RUX in pts with MF who were JAK inhibitor naive and showed greater reduction in RBC transfusion burden from baseline vs DAN in pts with MF who were JAK inhibitor experienced. Across both trials, ≥85% of pts treated with MMB maintained or improved transfusion intensity.

JAK inhibition can reduce GM-CSF signaling, which contributes to CMML pathobiology; ruxolitinib has been clinically evaluated in CMML demonstrating promising, but insufficient clinical activity. Modulation of biomarkers of disease activity with treatment including GM-CSF dependent STAT5 phosphorylation, MAPK, and PI3K signaling will be analyzed. We will also evaluate changes in mutational and cytogenetic burden with treatment as well as at baseline to identify predictive biomarkers of response.

Hydroxyurea was the most commonly used drug in patients with MF prior to the approval of ruxolitinib (RUX), a first-in-class Janus kinase 1/2 inhibitor (JAKi) that is widely approved for symptomatic patients with MF. In addition to RUX, the JAKis fedratinib and, more recently, pacritinib have also been approved by the US Food and Drug Administration... In patients with MF, RUX was the most commonly used agent in all lines of therapy. The greatest reduction in duration of MF treatment occurred from 1L to 2L. Most patients remained on 1L therapy through Week 24 and did not initiate 2L therapy until Week 156.

We performed comparative studies to evaluate the activity of pacritinib and the covalent BTK-inhibitors ibrutinib and zanubrutinib on mutated MYD88 relevant pro-survival signaling, as well as proliferation and survival in MYD88 mutated cell lines and primary MYD88-mutated WM cells...Lastly, pacritinib alone and combined with venetoclax induced high levels of apoptosis in BTKCys481Ser expressing covalent BTK-inhibitor resistant MYD88 mutated WM and ABC DLBCL lymphoma cells... Pacritinib more broadly extinguishes mutated MYD88 pro-survival signaling cascades (Fig 1.) and demonstrates high levels of apoptotic activity in mutated MYD88 WM and ABC DLBCL cells versus selective covalent BTK-inhibitors. Pacritinib also synergizes with covalent BTK- and BCL2 inhibitors and can overcome covalent BTK-inhibitor resistance related to mutated BTKCys481. Our studies provide a framework for investigating pacritinib in MYD88 mutated lymphomas.

Background: Pacritinib is a JAK1-sparing inhibitor of JAK2/IRAK1/ACVR1 that demonstrated symptom benefit measured by TSS (v2.0, excluding tiredness) vs best available therapy (BAT) in PERSIST-2, which enrolled cytopenic myelofibrosis patients with platelets ≤100×109/L. In cytopenic myelofibrosis patients enrolled in PERSIST-2, having a reduction of TSS≥10% on full-dose PAC was associated with OS benefit – a finding that has not been noted with other JAK inhibitors to date. By contrast, this association was not found with BAT, (82% of these patients received ruxolitinib). Thus, reductions in TSS in patients treated with PAC were associated with an OS benefit.

While Janus kinase (JAK) inhibitors such as ruxolitinib (RUX) and fedratinib (FED) may address symptoms and splenomegaly, they do not manage and may exacerbate anemia. Treatments for anemia include erythropoiesis-stimulating agents (ESAs), often in combination with RUX or FED, and androgens such as danazol; however, these have shown limited efficacy... In RUX/BAT-treated pts with MF who required RBC transfusions, continued treatment with RUX/BAT in most pts resulted in poor treatment outcomes compared with MMB. Specifically, treatment with MMB demonstrated an ability to deliver higher SVR, TI, and TSS response rates. The lower SVR35 rate in both arms, similar to the overall ITT population, was likely a result of lack of washout from prior JAK inhibitor treatment.

Momelotinib (MMB) is a Janus kinase (JAK) 1/JAK2/activin A receptor type 1 (ACVR1) inhibitor that has demonstrated spleen, symptom, and anemia benefits, including increases in hemoglobin (Hb) and reduction or elimination of red blood cell (RBC) transfusion requirements in pts with MF...Analyses were performed in the safety populations of S1 (N=430; MMB vs ruxolitinib [RUX], JAK inhibitor [JAKi] naive), S2 (N=156; MMB vs best available therapy [88.5% RUX], JAKi experienced), and MOMENTUM (N=195; MMB vs danazol, JAKi experienced)... These data demonstrate that when accounting for differences in known prognostic factors and effect modifiers as well as changes in RBC transfusion status over time, a consistent and statistically significant relationship was observed between transfusion status and OS across all 3 phase 3 MMB trials. Consistent with inclusion of transfusion status in DIPSS-plus risk assessment, these data validate TI status as a clinically relevant and meaningful endpoint that is prognostic for survival in JAKi-naive and JAKi-experienced disease settings.

Treatment with zilurgisertib monotherapy or in combination with RUX in this pt population was generally well tolerated, with predominantly grade 1/2 TEAEs. Reduced hepcidin levels were observed at all dose levels with both monotherapy and in combination with RUX, with greater control of hepcidin over time observed at higher zilurgisertib doses. Preliminary improvements in anemia were observed in non–transfusion-dependent pts during dose escalation, suggesting potential for therapeutic activity.