RESEARCH

BIOORTHOGONALLY-ACTIVATED PRODRUG THERAPY

 

Inspired by the wide-ranging notion of bioorthogonality, our lab focuses on the exploration and development of masking strategies capable of suppressing the bioactivity of chemotherapeutics and rendering them biochemically stable while “activatable” through highly-selective bioindependent processes, such as Pd or Au chemistry.

 

Our work on Pd-labile precursors of cytotoxic pyrimidine analogues (see Figure) was the first to demonstrate that non-biological transition-metal catalysts can be safely used to transform inactive chemicals into potent drugs in cell culture [1]. Following a series of studies [2-9], our lab has developed a broad range of bioorthogonal prodrugs and various catalyst-loaded devices that are capable of performing bioorthogonal catalytic reactions in vitro, ex vivo and in vivo.  

 

 

 

 

 

 

 

 

 

 

 

Key References:

 

[1] Weiss et al. Extracellular Palladium-Catalyzed Dealkylation of 5-Fluoro-1-Propargyl-Uracil as a Bioorthogonally-Activated Prodrug Approach. Nature Communications 2014, 5, 3277.

[2] Weiss et al. Development and Bioorthogonal Activation of Palladium-Labile Prodrugs of Gemcitabine. Journal of Medicinal Chemistry 2014, 57, 5395-5404.

[3] Rubio-Ruiz et al. Efficient Palladium-Triggered Release of Vorinostat from a Bioorthogonal Precursor. Journal of Medicinal Chemistry 2016, 59, 9974–9980.

[4] Pérez-López et al. Gold-Triggered Uncaging Chemistry in Living Systems. Angew. Chemie Int. Ed. 2017, 56, 12548.

[5] Bray et al. Bright insights into Palladium-triggered local chemotherapy. Chem. Sci. 2018, 9, 7354.

[6] Sancho-Albero et al. Cancer-derived exosomes loaded with ultrathin palladium nanosheets for targeted bioorthogonal catalysis. Nat. Catal. 2019, 2, 864.

 

Picture1.jpg

COOPERATIVE LIGAND-BASED DRUG DESIGN & PHENOTYPIC SCREENING

 

In the search for hits and leads that could target a wide range of kinases with relevance in cancer, we employ highly promiscuous kinase inhibitors as templates to design small molecule collections and to facilitate the search for enhanced physicochemical properties and, at the same time, the exploration of novel pharmacological features. To accelerate the discovery of bioactive inhibitors, our lab frontloads phenotypic analysis using selected cancer cell lines to guide subsequent chemical design towards specific cancer indications. By performing ligand-based design, library synthesis and phenotypic screening in an iterative manner (see Figure below), we facilitate the discovery of compounds with anticancer properties —regardless of the target involved— and suitable physicochemical properties to enter cells.

 

In the proof of concept studies [a, b], chemical design was biased towards breast cancer treatment (rather than to a particular target) by using human breast cancer cells as a discriminating cell model. Such pseudo target-agnostic strategy enabled the rapid identification of compounds that inhibited pathways involved in breast cancer survival and cell invasion and also disregarded compounds with low cell penetrability. Using this pragmatic approach, target deconvolution of identified hits and leads was largely simplified (= focused kinome screening), thereby assisting the mechanistic elucidation of the molecular targets and antitargets involved in the observed phenotype. This led to the discovery of novel ATP-competitive kinase inhibitors with unique properties, including the exquisitely selective mTOR inhibitor eCF309 [a] and the orally-available SRC inhibitor eCF506 [b], which is the first small molecule with subnanomolar IC50 for SRC that requires 3 orders of magnitude greater concentration to inhibit ABL. This is of relevance because the manifestation of cardiac events -especially in elderly patients- is a well-established adverse effect of ABL inhibition and many studies have shown that ABL plays a paradoxical anti-oncogenic role in breast cancer. Such off-target activities are absent in eCF506, which exhibits excellent water solubility and an optimal DMPK profile, halts SRC-associated neuromast collective cell migration in zebrafish embryos without inducing life-threatening heart defects and inhibits in vivo SRC phosphorylation in tumor xenografts [b].

Key References:

[a] Fraser et al. eCF309: a potent, selective and cell-permeable mTOR inhibitor. MedChemComm 2016, 7, 471-477.
[b] Fraser et al. Rapid Discovery and Structure–Activity Relationships of Pyrazolopyrimidines That Potently Suppress Breast Cancer Cell Growth via SRC Kinase Inhibition with Exceptional Selectivity over ABL Kinase. Journal of Medicinal Chemistry 2016, 59, 4697–4710.

[c] Myers et al. Development of Potent Inhibitors of Receptor Tyrosine Kinases by Ligand-Based Drug Design and Target-Biased Phenotypic Screening. Journal of Medicinal Chemistry 2018, 61, 2104–2110

[d] Cruz-López et al. Synthesis and Characterization of a Click-Assembled 18-Atom Macrocycle That Displays Selective AXL Kinase Inhibitory Activity ACS Omega 2019, 4, 21620-21626.

[e] Valero et al. Pyrazolopyrimide library screening in glioma cells discovers highly potent antiproliferative leads that target the PI3K/mTOR pathway Bioorganic & Medicinal Chemistry 2020, 28, 115215.