A phase 1 dose-escalation study of ARRY-520, a kinesin spindle protein inhibitor, in patients with advanced myeloid leukemias

Cancer. 2012 Jul 15;118(14):3556-64. doi: 10.1002/cncr.26664. Epub 2011 Dec 2.


Background: ARRY-520 selectively inhibits the mitotic kinesin spindle protein (KSP), which leads to abnormal monopolar spindle formation and apoptosis.

Methods: A phase 1 trial was conducted to establish the safety and the maximum tolerated dose (MTD) of ARRY-520 given as a 1-hour infusion in either a single dose or on a day 1, 3, and 5 divided-dose schedule per cycle in patients with advanced or refractory myeloid leukemias. Additional objectives were to characterize pharmacokinetics, assess preliminary clinical activity, and explore biomarkers of KSP inhibition with ARRY-520. A total of 36 patients with acute myelogenous leukemia (n = 34) or myelodysplastic syndromes (n = 2) with a median age of 66 years (range, 21-88 years) were enrolled: 15 in the single-dose schedule (dose levels: 2.5, 3.75, 4.5, and 5.6 mg/m(2)) and 21 in the divided-dose schedule (dose levels: 0.8, 1.2, 1.5, and 1.8 mg/m(2)/day).

Results: The MTD was 4.5 mg/m(2) total dose per cycle for both dose schedules. Dose-limiting toxicities included mucositis, exfoliative rash, hand-foot syndrome, and hyperbilirubinemia. Grades 3 or 4 reversible drug-related myelosuppression were observed in 33 of 36 patients. Plasma pharmacokinetic analyses revealed low clearance of ARRY-520 (~3 L/hour), a volume of distribution of ~450 L, and a median terminal half-life of >90 hours. Monopolar spindles were observed in blood mononuclear cells, through use of 4',6-diamidino-2-phenylindole nucleic acid stain and antitubulin antibodies.

Conclusions: On the basis of the relative lack of clinical activity, further development of ARRY-520 as an antileukemic agent was halted. (Clinicaltrials.gov identifier NCT00637052).

Publication types

  • Clinical Trial, Phase I
  • Multicenter Study

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antineoplastic Agents / administration & dosage
  • Antineoplastic Agents / adverse effects
  • Antineoplastic Agents / pharmacokinetics
  • Antineoplastic Agents / therapeutic use*
  • Drug Administration Schedule
  • Female
  • Humans
  • Kinesins / antagonists & inhibitors*
  • Leukemia, Myeloid / diet therapy*
  • Male
  • Maximum Tolerated Dose
  • Middle Aged
  • Myelodysplastic Syndromes / drug therapy*
  • Recurrence
  • Retreatment
  • Thiadiazoles / administration & dosage
  • Thiadiazoles / adverse effects
  • Thiadiazoles / pharmacokinetics
  • Thiadiazoles / therapeutic use*


  • Antineoplastic Agents
  • KIF11 protein, human
  • Thiadiazoles
  • filanesib
  • Kinesins

Associated data

  • ClinicalTrials.gov/NCT00637052