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Global Translational Medicine Role of HTS in cancer therapeutics

their effects on neural crest precursors derived from iPSCs understanding on the developmental process but also help
obtained from individuals with familial dysautonomia in elucidating the mechanisms of the disease; for instance,
(FD), a condition resulting from a single point mutation chemical genetic analysis using zebrafish embryos has been
in the I-κ‑B kinase complex‑associated protein (IKBKAP) employed to identify the role of PI3K and ERK in artery/
gene. To effectively screen extensive libraries, defining vein specification. This helps determine the cell fate of
disease-relevant conditions suitable for HTS is crucial. arteries or veins from angioblasts using GS4898, a known
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In this regard, the authors purified FD‑iPSC‑derived PI3K inhibitor. This study utilized the zebrafish model
neural crest (FD‑NC) precursors using flow cytometry to very effectively in screening small molecules against PI3K
elucidate why the disease specifically affects the peripheral inhibitors from the DiverSet E library (Chembridge).
nervous system. In addition, they focused on selecting Screening was performed in 96-well plates containing
a sensitive and disease-relevant readout. To achieve embryos in 1- or 2-celled stage and 6-somite stage, which
this, the authors developed a qRT‑PCR assay in a 384‑ are derived from zebrafish with a mutation (grlm ) in hey2/
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well format to measure levels of WT‑IKBKAP against gridlock that causes the lack of trunk and tail circulation due
the 18S internal control. They also determined whether to aortic dysmorphogenesis, a model resembling congenital
compounds increased both wild-type and mutant (MU) aortic coarctation in humans.
IKBKAP or acted via IKBKAP. The authors identified a Translational biomarkers can be viewed as clinically
potential hit, SKF‑86466, capable of rescuing IKBKAP relevant endpoint assay readouts that predict efficacy
transcription through modulation of intracellular cAMP in patients. However, their utility is constrained by the
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levels. Another study on cystic fibrosis, which results challenge of identifying and validating biomarkers for a
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from mutations in the CF transmembrane conductance range of target hits. 86,87 Most recent advancements in new
regulator (CFTR) gene required for an epithelial chloride disciplines such as genomics, proteomics, transcriptomics,
channel, aimed to correct the processing of F508del‑CFTR metabolomics, bioinformatics, and system biology could
using small molecules such as VX‑809, a CFTR corrector. impact the understanding of disease due to either loss
VX‑809 enhances the processing and folding of F508del‑ or gain of function or activation of genes that can be
CFTR in the endoplasmic reticulum and promotes its measured by CRISPR technologies. 88,89 Another approach
trafficking to the cell surface. 72 that supports drug discovery is RNAi that helps in hit
If the mechanism and root cause of the disease are not selection, lead optimization, and development of animal
well understood, inflammatory or cytotoxic agents can be models. For gene editing, CRISPR‑Cas9 technology is
used to induce the disease effects to recreate the cellular being used without altering the DNA. Integrated genomic
injury of interest. The last criterion is to determine the screening approach using CRISPR‑Cas9 and RNAi to
assay readout endpoint relevant to the clinical end point. induce loss of function has been used by Hong et al. in
To address this concern, more complex cell models and a a study to identify new potential therapeutic targets in
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range of microphysiological systems that better recapitulate a rare sarcoma. The researchers developed a patient-
in vivo physiological characteristics have emerged. In derived cancer cell line, CLF‑PED‑015‑T, from a patient
this regard, patient-derived organoids offer promise for with a rare undifferentiated sarcoma that holds most of the
personalized medicine due to their ability to mimic at least somatic genetic alterations found in an isolated metastatic
some functions of an organ. These organoids can be derived lesion. They used other complementary methods such
from iPSCs or donor tissue. In extension to this model, as CRISPR‑Cas9 and RNAi‑mediated loss‑of‑function
whole organism-based screens provide an additional level screens to identify CDK4 and XPO1 as druggable cancer
of physiological relevance beyond cell-based assays. For targets. A library of small molecules was screened from the
example, extensive research has been conducted in the Broad Institute Informer Set containing 72 drugs approved
pharmaceutical and biotechnology industries by utilizing by the FDA, 100 clinical candidates, and 268 biologically
organisms that can readily adapt to growth, such as yeast active chemical probes, to identify antiproliferative effects
and bacteria. 74-78 Following this step, the use of multicellular in the CLF‑PED‑015‑T cell line.
organisms, such as zebrafish, worms, and plants, becomes
crucial because cell-to-cell communication and multi- 3.1. Challenges to phenotypic screening
dimensional tissue organization of these organisms Phenotypic screening often suffers from a very potential
are more relevant to humans’. 78-82 For instance, a large- disadvantage that is target deconvolution, which is an
scale screening of 16,000-compound library identified important step for understanding compound MOA.
a compound called persynthamide (psy, 1) that delays Phenotypic screening provides the identification of multiple
S‑phase of the cell‑cycle and suppresses B‑Myb‑dependent off-target proteins or pathways, which might not link to a
mitotic defects. These models not only offer a deeper given biological output. This multiple target identification
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Volume 3 Issue 1 (2024) 8 https://doi.org/10.36922/gtm.2448