P2, N=6, Terminated, Medical College of Wisconsin | Trial completion date: May 2027 --> Oct 2024 | Active, not recruiting --> Terminated; After 6 patients were enrolled, it was determined that only patients with STAT5 activation were having a biochemical response to pacritinib treatment.

P1, N=10, Not yet recruiting, City of Hope Medical Center

In patients with myelofibrosis and platelets ≤ 100 × 109/L, achieving SVR on pacritinib, but not BAT (including ruxolitinib), was associated with significant OS benefit, suggesting that pacritinib may offer a unique survival advantage in patients with myelofibrosis and thrombocytopenia who achieve any SVR. Trial Registration: ClinicalTrials.gov number: NCT02055781.

Interestingly, pacritinib, but not other JAK inhibitors such as ruxolitinib, upadacitinib, or filgotinib, acted synergistically with lenvatinib in HCC cells. Immunohistochemical analysis of tumor sections revealed that pacritinib reduced Ki67 staining and phosphorylated IRAK1. Our findings suggest that pacritinib may be a promising therapeutic option for the treatment of advanced HCC, particularly in patients who have developed resistance to lenvatinib.

In this work, additional effort was applied to design new BIBR1532-based analogues with potential inhibitory activity against telomerase and acting as multitarget antitumor candidates to overcome the resistance problem...Compound 4l represented a very promising JAK1 inhibitory potential with a 0.46-fold change, compared to that of pacritinib reference standard (0.33-fold change). Besides, it showed a superior STAT3-inhibitory potential with a 0.22-fold change compared to sorafenib (0.33-fold change). Additionally, compound 4l downregulated TLR4 protein expression by 0.81-fold change compared to that of resatorvid (0.29-fold change)...Remarkably, compound 4l led to prominent reductions in tumor size and mass. Concurrent enhancements in biochemical, hematologic, histopathologic, and immunohistochemical parameters further confirmed the suppression of angiogenesis and inflammation, elucidating additional mechanisms by which compound 4l exerts its anticancer effects.

P2, N=65, Recruiting, National Cancer Institute (NCI) | Not yet recruiting --> Recruiting

P1, N=15, Not yet recruiting, Washington University School of Medicine

Our phase I graft-versus-host disease (GVHD) prevention trial of JAK2 inhibitor, pacritinib, (recommended phase II dose: 100mg po BID day 0 to +70) plus sirolimus and tacrolimus (PAC/SIR/TAC) demonstrated the regimen was safe and free of pan-JAK myelosuppression after allogeneic hematopoietic cell transplantation (alloHCT). The cumulative incidence of grade II-IV acute GVHD by day +100 with PAC/SIR/TAC was similar to historic SIR/TAC values (46 v 43%). While PAC/SIR/TAC suppressed pSTAT3 and Th1/Th17 cells, the regimen did not improve acute GVHD prevention.

P1/2, N=44, Not yet recruiting, The University of Texas Health Science Center at San Antonio

Pacritinib demonstrates consistent efficacy in patients with MF regardless of baseline platelet and hemoglobin counts.

P1, N=29, Completed, CTI BioPharma | Recruiting --> Completed

P1/2, N=26, Recruiting, Douglas Tremblay | Not yet recruiting --> Recruiting | Initiation date: Jan 2024 --> Sep 2024

Here, we report the novel combination of FDA-approved TrkA inhibitors (Entrectinib or Larotrectinib) and JAK2 inhibitors (Pacritinib or Ruxolitinib) synergistically inhibited in vitro growth of HER2-positive breast cancer cells and TNBC cells...The Entrectinib-Pacritinib combination suppressed orthotopic growth of HER2-positive Trastuzumab-refractory breast cancer xenografts and basal patient-derived xenograft (PDXs), reduced tumoral SOX2 and MYC, and induced apoptosis in both mouse models. The Entrectinib-Pacritinib combination inhibited overall metastatic burden, and brain and bone metastases of intracardially inoculated TNBC cells without toxicity. Together, our results demonstrate for the first time that co-inhibition of TrkA and JAK2 synergistically suppresses breast cancer growth and metastasis, thereby providing preclinical evidence that supports future clinical evaluations.

Various IRAK1 inhibitors, including Pacritinib and Rosoxacin, show therapeutic potential against malignancies and inflammatory diseases...Additionally, the emergence of selective IRAK1 degraders, such as JNJ-101, provides a novel strategy by targeting the scaffolding function of IRAK1. Thus, the evolving landscape of IRAK1-targeted approaches provides promising avenues for increasingly safe and effective therapeutic interventions for various diseases.

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

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

These collective observations highlight IRAK1's role in mitigating the anti-cancer effects of radiotherapy, partly through the activation of the NF-κB pathway. SUMMARY: IRAK1 enhances cervical cancer resistance to radiotherapy, with IR treatment reducing IRAK1 expression and increasing cancer cell vulnerability and apoptosis.

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

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

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

The loss of IRAK4, of IRAK4 kinase activity, of either Pellino protein, or of the nuclear localization sequence in IRAK1 sensitized p53-mutant zebrafish to radiation. Thus, the findings may lead to strategies for overcoming tumor resistance to conventional cancer treatments.

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.

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.

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.

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).

In primary patient cell lines from FLT3 wildtype (WT) patients, KME-0584 inhibits leukemia stem cell progenitor function as measured by the colony formation assay in methylcellulose with higher potency than IRAK4 inhibitor compounds that lack IRAK1 activity such as CA-4948 (Emavusertib)...Given that monocytic-like subtypes of AML are resistant to Venetoclax plus Azacitidine (VEN/AZA) (S Pei et...KME-0584 exhibits superior potency and efficacy to gilteritinib in the FLT3-ITD (D835Y) xenograft model after QD oral dosing, with sufficient PK and oral bioavailability across multiple species to support QD or BID dosing in the clinic. KME-0584 does not inhibit any of the major or minor cytochrome P450 enzymes at anticipated clinical concentrations and early indication from ongoing GLP toxicology studies suggest that it could be safely administered in humans. A clinical study of KME-0584 in relapsed/refractory AML and HR-MDS is currently planned to start in 1H 2024.

R289 is a prodrug that is converted to the active drug R835 in the gastrointestinal (GI) tract...The trial is currently recruiting at 9 US sites. The study has enrolled 7 patients in the dose escalation phase.

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.

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.

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.

Introduction: Our phase I graft-versus-host disease (GVHD) prevention trial of pacritinib (recommended phase II dose: 100mg po BID day 0 to +70, dose level 2) plus sirolimus (8-14ng/ml) and tacrolimus (3-7ng/ml) (PAC/SIR/TAC) demonstrated the regimen was safe and free of pan-JAK myelosuppression after allogeneic hematopoietic cell transplantation (alloHCT). While PAC/SIR/TAC successfully reduced pSTAT3, increased pSTAT5, and suppressed Th1 and Th17 cells, the regimen did not reduce acute GVHD risk. Completed phase II and III trials testing tocilizumab (anti-IL-6 monoclonal antibody, ACTRN12612000726853, ACTRN12614000266662) and now PAC reveal a biologic disconnect between effective IL-6/JAK2/pSTAT3 axis blockade and a disappointing lack of clinical improvement in acute GVHD prevention. We surmise uncontrolled T cell Aurora kinase A activity contributed to acute GVHD via CD28 costimulation in this trial.

The STK4 knockdown would upregulate IRAK1 and thus the activation of NF-κB activity revealed by the increase in the levels of proinflammatory cytokines, consequently impairing SS-b2-induced inhibition of liver cancer development. Consequently, SS-b2 effectively inhibited PLC by upregulating STK4 to suppress the IRAK1/NF-κB signaling axis and is a promising agent for treating this disease.

P1/2, N=40, Completed, H. Lee Moffitt Cancer Center and Research Institute | Active, not recruiting --> Completed

P1, N=60, Active, not recruiting, CTI BioPharma | Trial primary completion date: Aug 2023 --> Dec 2023