Preclinical activity and a pilot phase I study of pacritinib, an oral JAK2/FLT3 inhibitor, and chemotherapy in FLT3-ITD-positive AML


Activating FLT3 internal tandem duplication (FLT3-ITD) mutations in acute myeloid leukemia (AML) associate with inferior outcomes. We determined that pacritinib, a JAK2/FLT3 inhibitor, has in vitro activity against FLT3-ITD and tyrosine kinase domain (TKD) mutations. Therefore, we conducted a phase I study of pacritinib in combination with chemotherapy in AML patients with FLT3 mutations to determine the pharmacokinetics and preliminary toxicity and clinical activity. Pacritinib was administered at a dose of 100 mg or 200 mg twice daily following a 3 + 3 dose-escalation in combination with cytarabine and daunorubicin (cohort A) or with decitabine induction (cohort B). A total of thirteen patients were enrolled (five in cohort A; eight in cohort B). Dose limiting toxicities include hemolytic anemia and grade 3 QTc prolongation in two patients who received 100 mg. Complete remission was achieved in two patients in cohort A, one of whom had a minor D835Y clone at baseline. One patient in cohort B achieved morphologic leukemia free state. Seven patients (two in cohort A; five in cohort B) had stable disease. In conclusion, pacritinib, an inhibitor of FLT3-ITD and resistant-conferring TKD mutations, was well tolerated and demonstrated preliminary anti-leukemic activity in combination with chemotherapy in patients with FLT3 mutations.

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We would like to acknowledge CTI BioPharma for providing the drug and financial support for the trial and the service provided by The Ohio State University Comprehensive Cancer Center Shared Resources and Cores.


This work was supported by CTI BioPharma. It was also supported by the National Institute of Health grants R01 CA138744 to Sharyn D. Baker, R35 CA197734 to John C. Byrd and Cancer Center Support Grant P30 CA021765, funds from The Ohio State University Comprehensive Cancer Center Pelotonia foundation, and Eli Lilly fellowship to Jae Yoon Jeon.

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Correspondence to Bhavana Bhatnagar.

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Research support was provided by CTI BioPharma to Bhavana Bhatnagar, and all other authors declare that they have no conflict of interest.

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Jeon, J.Y., Zhao, Q., Buelow, D.R. et al. Preclinical activity and a pilot phase I study of pacritinib, an oral JAK2/FLT3 inhibitor, and chemotherapy in FLT3-ITD-positive AML. Invest New Drugs 38, 340–349 (2020).

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  • Acute myeloid leukemia
  • Pacritinib
  • FLT3
  • Clinical trials
  • Chemotherapy