title: The FLT3 inhibitor PKC412 in combination with cytostatic drugs in vitro in acute myeloid leukemia.
abstract: An internal tandem duplication of FLT3 (FLT3/ITD) occurs in approximately 25% of newly diagnosed AML. PKC412 inhibits the growth of leukemic cell lines with FLT3 mutations such as the MV4-11. This study evaluated the in vitro effects of the combination of PKC412 and ara-C or daunorubicin, studying the effect of co-incubation, pre-incubation and sequential incubation of the drugs in patient samples and cell lines. Thirty-three patients with AML were included. Two cell lines were studied; MV4-11 that expresses the FLT3/ITD and HL-60 that does not. In the patient cells PKC412 exerted its effect at concentrations between 0.1 and 2.0 microM. For MV4-11 cells concentrations down to 1 nM were effective. In patient samples, the results of co-incubation of PKC412 with ara-C were synergistic in 5%, additive in 67%, sub additive in 17% and antagonistic in 11% of the cases. In patient cells, incubations with ara-C and PKC412 resulted in synergistic effects in 17% of the FLT3/ITD positive samples compared to 0% synergistic in the FLT3/ITD negative samples (p < 0.01). Antagonistic effects were more common in the FLT3/ITD negative samples. The timing of the drugs had little impact on the effect. In cell lines, antagonistic effects were seen frequently in HL-60 (90%) and less so in MV4-11 (60%) regardless of sequence or timing of the drugs. The combination of daunorubicin and PKC412 resulted in more synergistic and less antagonistic effects compared to combinations with ara-C, in both patient material and cell lines. The combination of Lonafarnib, a farnesyl-transferase inhibitor (FTI) and PKC412 had additive and synergistic effects in both FLT3/ITD positive and negative cell lines. In conclusion, the combination of PKC412 together with chemotherapeutic drugs is more effective in FLT3/ITD positive AML cells. Antagonistic effects can be seen, especially in patient samples without FLT3/ITD. Also, the combination of PKC412 and the farnesylinhibitor lonafarnib should be further explored.
authors.affiliation: Department of Hematology, Karolinska University Hospital Huddinge, Stockholm, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Möllgård
authors.forename: Stefan
authors.initials: S
authors.lastname: Deneberg
authors.forename: Hareth
authors.initials: H
authors.lastname: Nahi
authors.forename: Sofia
authors.initials: S
authors.lastname: Bengtzen
authors.forename: Kerstin
authors.initials: K
authors.lastname: Jonsson-Videsäter
authors.forename: Thoas
authors.initials: T
authors.lastname: Fioretos
authors.forename: Anna
authors.initials: A
authors.lastname: Andersson
authors.forename: Christer
authors.initials: C
authors.lastname: Paul
authors.forename: Sören
authors.initials: S
authors.lastname: Lehmann
mesh_terms: D000328:Adult; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D004357:Drug Synergism; D005260:Female; D018922:HL-60 Cells; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000201:enzymology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D019311:Staurosporine / Q000031:analogs & derivatives* / Q000494:pharmacology; D051941:fms-Like Tyrosine Kinase 3 / Q000037:antagonists & inhibitors* / Q000235:genetics
chemical_list: C497970:FLT3 protein, human; D051941:fms-Like Tyrosine Kinase 3; D019311:Staurosporine; C059539:midostaurin