LETTER LETTER REPLY TO OEGEMA ET AL.: CFI-400945 and Polo-like 4 inhibition

Masanori Kawakamia, Lisa Maria Mustachioa, Lin Zhenga, Yulong Chena, Jaime Rodriguez-Canalesb, Barbara Minob, Jonathan M. Kuriea, Jason Roszikc,d, Pamela Andrea Villalobosb, Kelsie L. Thue, Jennifer Silvestere, David W. Cescone,f, Ignacio I. Wistubab, Tak W. Make,g,1, Xi Liua, and Ethan Dmitrovskya,h,i

In “CFI-400945 is not a selective cellular PLK4 inhibitor,” consistent with this bimodal nature. Thus, Oegema et al. (1) raise thoughtful comments about our overduplication occurred at the 20- to 50-nM concen- article (2). We appreciate their interest and critique. trations, but much less so at the 500-nM dosage. They propose that CFI-400945 activity was not from Different dosages of centrinone and CFI-400945 were Polo-like kinase (PLK4) inhibition and argue that antineo- used (1), making it challenging to compare these PLK4 plastic activity was through (1), rather inhibitors. Also, while7doftreatmentsareusedinfigure than PLK4 inhibition (2). 1A of ref. 1, treatment durations are not indicated for figure often share related catalytic pockets, and 1 B and C of ref. 1. Adding to the difficulty of interpretation targeting one kinase without affecting another is difficult to is that a single lung cancer cell line was examined (1). In achieve. This is true for CFI-400945 (2) and centrinone, the contrast, we explored CFI-400945 effects on centrosome PLK4 inhibitor (3) used by Oegema et al. (1). CFI-400945 is numbers after only 24 h of treatment (limiting off-target

(by IC50) 38-fold more potent in causing PLK4 inhibition effects) and in diverse lung cancer cell lines (2). Likewise, than in antagonizing Aurora B kinase (4, 5). Despite their lower dosages of CFI-400945 were used in our study (2) claim otherwise, this CFI-400945 property is cited (2). In- than in theirs (1). Increased centrosome numbers occurred deed, CFI-400945 actions beyond PLK4 inhibition are at a dosage as low as 10 nM (2), making it improbable that not formally excluded (2). In addition, other findings that Aurora B kinase inhibition after CFI-400945 treatment

we discuss here question their major conclusions. alone drove this response, given that its IC50 is 2.8 nM Oegema et al. (1) compare treatment with CFI- for PLK4 and 98 nM for Aurora B kinase (4, 5). CFI- 400945 to that of the PLK4 inhibitor centrinone (3). 400945 treatments at dosages higher than 50 nM re- They found that CFI-400945 treatment did not confer duced the accumulation of supernumerary centrosome depletion at the dosages and schedules (2). These findings are consistent with a bimodal inhibition studied (1). We do not contest that centrinone can of PLK4. If cytokinesis failure by Aurora B kinase inhibition cause centrosome depletion. However, the observed were primarily responsible for CFI-400945 actions, super- findings are likely due to bimodal PLK4 inhibition (6). numerary centrosomes should increase at higher treat- Low-dose CFI-400945 treatment suppresses PLK4 ment dosages, but this was not found (1, 2). autophosphorylation (2). PLK4 protein stability and ac- In summary, CFI-400945 can inhibit Aurora B kinase, tivity thereby increase, leading to overdupli- as is cited (2). We concur with Oegema et al. (1) that cation. However, high CFI-400945 treatment dosages PLK4 is an attractive antineoplastic target. However, can fully antagonize PLK4 activity, abrogating these antineoplastic actions of CFI-400945 (2) remain consis- effects. Our findings in lung cancer cells (2) are tent with those engaged by PLK4 inhibition.

1 Oegema K, Davis RL, Lara-Gonzalez P, Desai A, Shiau AK (2018) CFI-400945 is not a selective cellular PLK4 inhibitor. Proc Natl Acad Sci USA 115:E10808–E10809. 2 Kawakami M, et al. (2018) Polo-like kinase 4 inhibition produces and apoptotic death of lung cancers. Proc Natl Acad Sci USA 115:1913–1918.

aDepartment of Thoracic/Head and Neck Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030; bDepartment of Translational Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030; cDepartment of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030; dDepartment of Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030; eThe Campbell Family Institute for Breast Cancer Research at Princess Margaret Cancer Centre, University Health Network, Toronto, ON M5G 2M9, Canada; fDepartment of Medicine, University of Toronto, Toronto, ON M5G 1L7, Canada; gDepartment of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada; hDepartment of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030; and iLeidos Biomedical Research, Frederick National Laboratory for Cancer Research, Frederick, MD 21701 Author contributions: M.K., L.M.M., L.Z., Y.C., J.R.-C., B.M., J.M.K., J.R., P.A.V., K.L.T., J.S., D.W.C., I.I.W., T.W.M., X.L., and E.D. wrote the paper. Conflict of interest statement: K.L.T., J.S., D.W.C., and T.W.M. declare that CFI-400945 is owned and being developed by the University Health Network. The remaining authors declare no conflict of interest. Published under the PNAS license. 1Email: [email protected]. Published online October 30, 2018.

E10810–E10811 | PNAS | November 13, 2018 | vol. 115 | no. 46 www.pnas.org/cgi/doi/10.1073/pnas.1813967115 Downloaded by guest on September 23, 2021 3 Wong YL, et al. (2015) Cell biology. Reversible centriole depletion with an inhibitor of Polo-like kinase 4. Science 348:1155–1160. 4 Mason JM, et al. (2014) Functional characterization of CFI-400945, a Polo-like kinase 4 inhibitor, as a potential anticancer agent. Cancer Cell 26:163–176. 5 Sampson PB, et al. (2015) The discovery of Polo-like kinase 4 inhibitors: Identification of (1R,2S)-2-(3-((E)-4-(((cis)-2,6-dimethylmorpholino)methyl)styryl)-1H-indazol- 6-yl)-5′-methoxyspiro[cyclopropane-1,3′-indolin]-2′-one (CFI-400945) as a potent, orally active antitumor agent. J Med Chem 58:147–169. 6 Holland AJ, Cleveland DW (2014) Polo-like kinase 4 inhibition: A strategy for cancer therapy? Cancer Cell 26:151–153.

Kawakami et al. PNAS | November 13, 2018 | vol. 115 | no. 46 | E10811 Downloaded by guest on September 23, 2021