Rationally derived drug combinations with the novel Mcl-1 inhibitor EU-5346 in breast cancer

  • Sonia Vallet
  • Fengjuan Fan
  • Stefano Malvestiti
  • Martin Pecherstorfer
  • Martin Sattler
  • Andreas Schneeweiss
  • Henning Schulze-Bergkamen
  • Joseph T. Opferman
  • Michael H. Cardone
  • Dirk Jäger
  • Klaus PodarEmail author
Preclinical study



Recent studies have emphasized a key role for the anti-apoptotic Bcl-2 family member Mcl-1 in conferring tumor cell survival and drug resistance in breast cancer (BC). Mcl-1 inhibitors, such as the BH3-mimetic EU-5346, therefore represent an exciting new class of targeting agents and are a current focus of widespread cancer-drug development efforts.


ONCOMINE analysis was utilized to compare expression profiles of Bcl-2 family members across all major BC subgroups. Potential toxicities of EU-5346 were evaluated using iPS-generated cardiomyocytes, blood cells and astrocytes. The anti-BC cell activity of EU-5346-based therapies was evaluated using [3H]-thymidine uptake and spheroid-forming assays as well as immunoblotting and the Chou-Talalay method. Protein level-based activity of EU-5346, the specific anti-Bcl-2 inhibitor ABT-199 and the specific anti-Bcl-xL inhibitor WEHI-539 was verified in Mcl-1Δ/null versus Mcl-1wt/wt MEFs.


We previously demonstrated significant anti-tumor activity of EU-5346 in all BC subtypes. Our present results go further and suggest that EU-5346 may induce limited adverse events such as cardiotoxicity, hematotoxicity, and neurotoxicity, frequently observed with other BH3 mimetics. As demonstrated by our mathematical scoring model, the prediction of EU-5643-induced IC50 not only relies on the protein level of Mcl-1 but also on Bak, Bim, and Noxa. Synergistic anti-BC activity of low-dose EU-5346 with the BH3 mimetics ABT-199 or WEHI-539 was observed only in those BC cells expressing Bcl-2 or Bcl-xL, respectively. Similarly, when combined with tamoxifen or trastuzumab, low-dose EU-5346 induced significant anti-BC activity in hormone receptor positive or Her2-positive BC cells, respectively. Finally, EU-5346 in combination with paclitaxel induced synergistic anti-BC activity in both paclitaxel-sensitive and paclitaxel-resistant TNBC cells.


These data strongly support the further clinical development of EU-5346 to improve BC patient survival.


Breast cancer Mcl-1 BH3 mimetics Mathematical scoring model Combination therapies 



Breast cancer


Triple negative


Mitochondrial outer membrane permeabilization


Myeloid cell leukemia-1


Bcl-2 homology 3


The Cancer Genome Atlas (TCGA)


Hormone receptor


Induced pluripotent stem cell


Murine embryonic fibroblasts


Peripheral blood mononuclear cells



SM is the recipient of a DGHO/ Jose Carreras stipend. KP is the recipient of a B. Braun Stiftungs Grant. MP and KP received research support from Roche Pharmaceuticals. We cordially thank Muhammad Hasan Bashari for technical assistance.

Author contributions

SV conceived of the study, designed experiments, analyzed data, and wrote the manuscript. FF and SM performed experiments and participated in data analysis and interpretation. MS, JTO and MHC conceived of the study and participated in data analysis and interpretation. MP, AS and DJ made substantial contributions to the acquisition and interpretation of data. KP conceived of the study, designed and coordinated experiments, analyzed and interpreted data and wrote the manuscript. All authors were involved in revising the manuscript critically for important intellectual content. All authors approved the final version of the manuscript.

Compliance with ethical standards

Conflict of interest

KP received speaker honorarium from Celgene, Janssen, and Amgen. MP and KP received research support from Roche Pharmaceuticals. JTO received consultant honorarium and research support from AbbVie. DJ received consultant honorarium from Bayer, Amgen, MSD, CureVac, Roche, BMS. MHC is the co-funder, president and CEO of Eutropics, Inc. The remaining authors declare no conflict of interest.

Ethical approval

This study complied with current laws of Germany, Austria and USA. The collection and use of primary cells has been approved by the Ethics committee of the Medical Faculty, University of Heidelberg (Approval Number 022/2013).

Informed consent

Informed consent was obtained in accordance with the Declaration of Helsinki. This article does not contain any studies with animals performed by any of the authors.

Supplementary material

10549_2018_5022_MOESM1_ESM.pdf (168 kb)
Supplementary material 1 (PDF 167 KB)


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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  • Sonia Vallet
    • 1
    • 2
  • Fengjuan Fan
    • 1
    • 3
  • Stefano Malvestiti
    • 1
  • Martin Pecherstorfer
    • 2
  • Martin Sattler
    • 4
    • 5
  • Andreas Schneeweiss
    • 1
  • Henning Schulze-Bergkamen
    • 1
  • Joseph T. Opferman
    • 6
  • Michael H. Cardone
    • 7
  • Dirk Jäger
    • 1
    • 8
  • Klaus Podar
    • 1
    • 2
    Email author
  1. 1.Department of Medical Oncology, National Center for Tumor Diseases (NCT)University of HeidelbergHeidelbergGermany
  2. 2.Department of Internal Medicine II, University Hospital KremsKarl Landsteiner University of Health SciencesKrems an der DonauAustria
  3. 3.Institute of Hematology, Union Hospital, Tongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina
  4. 4.Department of Medical OncologyDana-Farber Cancer InstituteBostonUSA
  5. 5.Department of MedicineHarvard Medical SchoolBostonUSA
  6. 6.St. Jude Children’s Research HospitalMemphisUSA
  7. 7.Eutropics Pharmaceuticals, Inc.CambridgeUSA
  8. 8.German Cancer Research Center (DKFZ)Applied Tumor ImmunityHeidelbergGermany

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