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Interface of Evolution and Structure Based Drug Design

Our Lab

Constraining evolution and avoiding drug resistance

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Drug resistance occurs when, through evolution, a disease no longer responds to medications. Resistance impacts the lives of millions, limiting the effectiveness of many of our most potent drugs. This often happens under the selective pressure of therapy in bacterial, viral and fungal infections and cancer due to their rapid evolution.

We combine a variety of experimental and computational techniques to understand the molecular basis of drug resistance. Our new paradigm of drug design minimizes chances of resistance. Realizing that disrupting the drug target’s activity is necessary but not sufficient for developing a robust drug that avoids resistance.

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Research Focus

Strategies and Systems

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We use multidisciplinary approaches, combining crystallography, enzymology, molecular dynamics and organic chemistry, to elucidate the molecular mechanisms of drug resistance. Resistance occurs when a heterogeneous populations of a drug target is challenged by the selective pressure of a drug. In cancer and viruses this heterogeneity is partially caused APOBEC3’s. We discovered resistance mutations occur either where drugs physically contact regions of the drug target that are not essential for substrate recognition or alter the ensemble dynamics of the drug target favoring substrate. We leverage these insights into a new strategies in structure-based drug design to minimize the likelihood for resistance by designing inhibitors to stay within the substrate envelope. This strategy not only describes most of the primary drug resistance for HIV, Hepatitis C viral protease inhibitors and influenza neuraminidase, but is generally applicable in the development of novel drugs that are less susceptible to resistance.

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Publications

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Total: 1 results
  • Avoiding Drug Resistance by Substrate Envelope-Guided Design: Toward Potent and Robust HCV NS3/4A Protease Inhibitors.

    Author(s): Matthew AN, Zephyr J, Nageswara Rao D, Henes M, Kamran W, Kosovrasti K, Hedger AK, Lockbaum GJ, Timm J, Ali A, Kurt Yilmaz N, Schiffer CA
    Related Articles

    Avoiding Drug Resistance by Substrate Envelope-Guided Design: Toward Potent and Robust HCV NS3/4A Protease Inhibitors.

    mBio. 2020 Mar 31;11(2):

    Authors: Matthew AN, Zephyr J, Nageswara Rao D, Henes M, Kamran W, Kosovrasti K, Hedger AK, Lockbaum GJ, Timm J, Ali A, Kurt Yilmaz N, Schiffer CA

    Abstract
    Hepatitis C virus (HCV) infects millions of people worldwide, causing chronic liver disease that can lead to cirrhosis, hepatocellular carcinoma, and liver transplant. In the last several years, the advent of direct-acting antivirals, including NS3/4A protease inhibitors (PIs), has remarkably improved treatment outcomes of HCV-infected patients. However, selection of resistance-associated substitutions and polymorphisms among genotypes can lead to drug resistance and in some cases treatment failure. A proactive strategy to combat resistance is to constrain PIs within evolutionarily conserved regions in the protease active site. Designing PIs using the substrate envelope is a rational strategy to decrease the susceptibility to resistance by using the constraints of substrate recognition. We successfully designed two series of HCV NS3/4A PIs to leverage unexploited areas in the substrate envelope to improve potency, specifically against resistance-associated substitutions at D168. Our design strategy achieved better resistance profiles over both the FDA-approved NS3/4A PI grazoprevir and the parent compound against the clinically relevant D168A substitution. Crystallographic structural analysis and inhibition assays confirmed that optimally filling the substrate envelope is critical to improve inhibitor potency while avoiding resistance. Specifically, inhibitors that enhanced hydrophobic packing in the S4 pocket and avoided an energetically frustrated pocket performed the best. Thus, the HCV substrate envelope proved to be a powerful tool to design robust PIs, offering a strategy that can be translated to other targets for rational design of inhibitors with improved potency and resistance profiles.IMPORTANCE Despite significant progress, hepatitis C virus (HCV) continues to be a major health problem with millions of people infected worldwide and thousands dying annually due to resulting complications. Recent antiviral combinations can achieve >95% cure, but late diagnosis, low access to treatment, and treatment failure due to drug resistance continue to be roadblocks against eradication of the virus. We report the rational design of two series of HCV NS3/4A protease inhibitors with improved resistance profiles by exploiting evolutionarily constrained regions of the active site using the substrate envelope model. Optimally filling the S4 pocket is critical to avoid resistance and improve potency. Our results provide drug design strategies to avoid resistance that are applicable to other quickly evolving viral drug targets.

    PMID: 32234812 [PubMed - in process]

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Contact Us

Office:
Lazare Research Building 828
Campus Map (pdf)

Phone:
508-856-8008 (office)

Email:
Celia.Schiffer@umassmed.edu

Mailing Address:
University of Massachusetts Medical School
Attn: Dr. Celia Schiffer/BMP department
364 Plantation St LRB828
Worcester, MA 01605

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We are always interested in applications from qualified candidates at postdoctoral and research associate levels.

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Undergraduates interested in pursuing a PhD at UMass Medical School should apply directly to the Graduate School of Biomedical Sciences Program.