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Optimization of drug combinations using Feedback System Control

Abstract

We describe a protocol for the discovery of synergistic drug combinations for the treatment of disease. Synergistic drug combinations lead to the use of drugs at lower doses, which reduces side effects and can potentially lead to reduced drug resistance, while being clinically more effective than the individual drugs. To cope with the extremely large search space for these combinations, we developed an efficient combinatorial drug screening method called the Feedback System Control (FSC) technique. Starting with a broad selection of drugs, the method follows an iterative approach of experimental testing in a relevant bioassay and analysis of the results by FSC. First, the protocol uses a cell viability assay to generate broad dose-response curves to assess the efficacy of individual compounds. These curves are then used to guide the dosage input of each drug to be tested in combination. Data from applied drug combinations are input into the differential evolution (DE) algorithm, which predicts new combinations to be tested in vitro. This process identifies optimal drug-dose combinations, while saving orders of magnitude in experimental effort. The complete optimization process is estimated to take 4 weeks. FSC does not require insight into the disease mechanism, and it has therefore been applied to find combination therapies for many different pathologies, including cancer and infectious diseases, and it has also been used in organ transplantation.

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Figure 1: A schematic representation of the FSC technique, showing the five main components of the optimization process.
Figure 2: Illustration of the differential evolution algorithm.
Figure 3: Regression analysis of combinatorial data.
Figure 4: Schematic drawing of a smooth response surface.
Figure 5: Schematic drawing of reported FSC applications.

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Acknowledgements

C.-M.H. acknowledges the support from the Ben Rich-Lockheed Martin Professor Endowment Fund and the Bill and Melinda Gates Foundation. P.N.-S. and A.W.G. acknowledge the support of KWF, the Dutch Cancer Society (Project VU 2014-7234). The authors acknowledge EPFL for financial support. We appreciate A.M. Silva for providing the sketch for Figure 2.

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Authors and Affiliations

Authors

Contributions

P.N.-S. conceived and designed the protocol, and wrote the manuscript; X.D. designed the protocol, modeled the data, delivered the code and wrote the manuscript; A.W. designed the protocol, delivered the code and wrote the manuscript; C.-M.H. conceived the FSC technology and participated in data modeling, data interpretation and writing of the manuscript; P.J.D. participated in data interpretation and writing of the manuscript; H.v.d.B. initiated the collaboration and participated in data interpretation, and in writing of the manuscript; A.W.G. designed the study, participated in data interpretation and contributed to writing of the manuscript. All authors read and approved the final manuscript.

Corresponding authors

Correspondence to Patrycja Nowak-Sliwinska or Chih-Ming Ho.

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Competing interests

All authors are the co-inventors on the FSC-related patents.

Supplementary information

Supplementary Text and Figures

Supplementary Note and Supplementary Tutorial (PDF 220 kb)

Supplementary Data

Example dataset for the refined search, providing an example of regression analysis performed in MATLAB. (XLS 111 kb)

Supplementary Software (ZIP 4 kb)

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Nowak-Sliwinska, P., Weiss, A., Ding, X. et al. Optimization of drug combinations using Feedback System Control. Nat Protoc 11, 302–315 (2016). https://doi.org/10.1038/nprot.2016.017

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