title: Results of a phase 2 study of pacritinib (SB1518), a JAK2/JAK2(V617F) inhibitor, in patients with myelofibrosis.
abstract: Pacritinib (SB1518) is a Janus kinase 2 (JAK2), JAK2(V617F), and Fms-like tyrosine kinase 3 inhibitor that does not inhibit JAK1. It demonstrated a favorable safety profile with promising efficacy in phase 1 studies in patients with primary and secondary myelofibrosis (MF). This multicenter phase 2 study further characterized the safety and efficacy of pacritinib in the treatment of patients with MF. Eligible patients had clinical splenomegaly poorly controlled with standard therapies or were newly diagnosed with intermediate- or high-risk Lille score. Patients with any degree of cytopenia were eligible. Thirty-five patients were enrolled. At entry, 40% had hemoglobin <10 g/dL and 43% had platelets <100 000× 10(9)/L. Up to week 24, 8 of 26 evaluable patients (31%) achieved a ≥35% decrease in spleen volume determined by magnetic resonance imaging and 14 of 33 (42%) attained a ≥50% reduction in spleen size by physical examination. Median MF symptom improvement was ≥50% for all symptoms except fatigue. Grade 1 or 2 diarrhea (69%) and nausea (49%) were the most common treatment-emergent adverse events. The study drug was discontinued in 9 patients (26%) due to adverse events (4 severe). Pacritinib is an active agent in patients with MF, offering a potential treatment option for patients with preexisting anemia and thrombocytopenia. This trial was registered at www.clinicaltrials.gov as #NCT00745550.
authors.affiliation: Moffitt Cancer Center, Tampa, FL;
authors.forename: Rami S
authors.identifier: http://orcid.org/0000-0002-1876-5269
authors.initials: RS
authors.lastname: Komrokji
authors.affiliation: Peter McCallum Cancer Center, Melbourne, Australia; Sir Peter MacCallum Department of Oncology.
authors.forename: John F
authors.initials: JF
authors.lastname: Seymour
authors.affiliation: Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne, Australia; Royal Melbourne Hospital, Melbourne, Australia;
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Roberts
authors.affiliation: Dana-Farber Cancer Institute, Boston, MA;
authors.forename: Martha
authors.initials: M
authors.lastname: Wadleigh
authors.affiliation: Royal Adelaide Hospital, Adelaide, Australia;
authors.forename: L Bik
authors.initials: LB
authors.lastname: To
authors.affiliation: Mayo Clinic, Scottsdale, AZ;
authors.forename: Robyn
authors.initials: R
authors.lastname: Scherber
authors.affiliation: Moffitt Cancer Center, Tampa, FL;
authors.forename: Elyce
authors.initials: E
authors.lastname: Turba
authors.affiliation: Independent Consultant for S*BIO Pte Ltd., Singapore;
authors.forename: Andrew
authors.initials: A
authors.lastname: Dorr
authors.affiliation: S*BIO Pte Ltd., Singapore; and.
authors.forename: Joy
authors.initials: J
authors.lastname: Zhu
authors.affiliation: CTI BioPharma, Seattle, WA.
authors.forename: Lixia
authors.initials: L
authors.lastname: Wang
authors.affiliation: CTI BioPharma, Seattle, WA.
authors.forename: Tanya
authors.initials: T
authors.lastname: Granston
authors.affiliation: CTI BioPharma, Seattle, WA.
authors.forename: Mary S
authors.initials: MS
authors.lastname: Campbell
authors.affiliation: Mayo Clinic, Scottsdale, AZ;
authors.forename: Ruben A
authors.initials: RA
authors.lastname: Mesa
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001952:Bridged-Ring Compounds / Q000009:adverse effects / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D053614:Janus Kinase 2 / Q000037:antagonists & inhibitors*; D008297:Male; D008875:Middle Aged; D055728:Primary Myelofibrosis / Q000150:complications / Q000188:drug therapy* / Q000473:pathology; D011743:Pyrimidines / Q000009:adverse effects / Q000627:therapeutic use*; D013154:Spleen / Q000187:drug effects / Q000473:pathology; D013163:Splenomegaly / Q000150:complications / Q000188:drug therapy / Q000473:pathology; D051941:fms-Like Tyrosine Kinase 3 / Q000037:antagonists & inhibitors*
chemical_list: C561234:11-(2-pyrrolidin-1-ylethoxy)-14,19-dioxa-5,7,26-triazatetracyclo(19.3.1.1(2,6).1(8,12))heptacosa-1(25),2(26),3,5,8,10,12(27),16,21,23-decaene; D001952:Bridged-Ring Compounds; D011743:Pyrimidines; D051941:fms-Like Tyrosine Kinase 3; D053614:Janus Kinase 2