Biology subjects

Roberts, T. M.

Publications and source records attributed to Roberts, T. M..

4 recordsLinked to original sources

bioRxiv2026

Targeting PI3Kβ-dependent cancer with a novel small molecule inhibitor, GT220

PI3K{beta} is a critical oncogenic driver in cancers harboring PTEN loss or PIK3CB alterations, yet effective and selective PI3K{beta}-targeted therapies remain elusive. Here, we report the development and preclinical characterization of GT220, a highly selective and potent small-molecule PI3K{beta} inhibitor developed through integrated artificial-intelligence-driven design with medicinal chemistry and pharmacologic optimization. GT220 exhibits exceptional biochemical selectivity for PI3K{beta}, binding with sub-nanomolar affinity and with minimal activity against other class I PI3K isoforms or the broader protein kinome. In cellular models, GT220 potently suppresses AKT phosphorylation and selectively inhibits viability of PTEN-deficient cancer cells, while sparing PTEN/PIK3CB wild-type and PI3K-dependent cells. In vivo, GT220 achieves a favorable tumor exposure with sustained PI3K{beta} pathway inhibition and demonstrates robust antitumor efficacy and good tolerability in PTEN-deficient breast cancer xenograft models. In contrast, GT220 shows no antitumor activity or pathway inhibition in PTEN-wild-type or PI3K-dependent tumors, underscoring its context-dependent mechanism of action. Collectively, these findings establish GT220 as a promising next-generation PI3K{beta} inhibitor and provide a strong preclinical rationale for precision targeting of PI3K{beta}-dependent cancers.

cancer biology↗

bioRxiv2025

Statin-dye conjugates for selective targeting of KRAS mutant cancer cells

Over 90% of pancreatic ductal adenocarcinoma (PDAC) patients involve KRAS mutations (KRASMUT), for which current treatment options are limited. Statins, commonly used to lower cholesterol, have demonstrated certain selective toxicity towards KRAS-transformed cells, prompting the question of whether statins could achieve selective uptake specifically in KRASMUT cells. To investigate this, we synthesized statin-dye conjugates by attaching a fluorescent dye (Cy5.5) to two statins: simvastatin and pravastatin, aiming to assess whether selective uptake indeed occurs. Our findings revealed that these conjugates exhibited markedly enhanced uptake in KRASMUT cells compared to KRAS wild-type (KRASWT) cells. Given the magnitude of the selective uptake, we realized that the uptake of these conjugates itself is of considerable intrinsic interests. We evaluated the uptake of these conjugates in both KRASMUT and KRASWT cells and examined their potential to selectively target KRASMUT pancreatic cancer cells (PCCs) using an engineered PDAC tumor model co-cultured with PCCs and cancer-associated fibroblasts (CAFs). Our findings indicate that KRASMUT cancer cells exhibited higher uptake of statin-Cy5.5 conjugates via enhanced macropinocytosis compared to KRASWT cancer cells and CAFs. We also found enhanced uptake of the statin-Cy5.5 conjugate in MCF10A cells with PTEN deficiency, a condition known to elevate macropinocytosis, compared to control MCF10A cells with wild-type PTEN. Notably, in the PCC and CAF co-culture model, the pravastatin-Cy5.5 conjugate selectively killed KRASMUT PCCs without affecting the KRASWT CAFs. These findings highlight the potential of stain-drug conjugates as targeted delivery vehicles for KRASMUT cancer therapy.

cancer biology↗

bioRxiv2021

Targeting EGFR in glioblastoma with a novel brain-penetrant small molecule EGFR-TKI

Epidermal growth factor receptor (EGFR) is mutated or amplified in a majority of glioblastoma (GBM), and its mutation and focal amplification correlate with a more aggressive disease course. However, EGFR-directed tyrosine kinase inhibitors (TKIs) tested to date have yielded minimal clinical benefit. Here, we report a novel covalent-binding EGFR-TKI, CM93, as a potential drug to target adult GBMs with aberrant EGFR. CM93 has extraordinary brain exposure, with a brain-to-plasma ratio greater than 20-fold at estimated steady state. While all approved EGFR-TKIs are subject to extensive efflux transporter activity, CM93 does not inhibit the P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) efflux transporters in Caco-2 cells at expected clinically relevant plasma concentrations. Equally, CM93 demonstrates moderate absorption and permeation in Caco-2 cell monolayers with efflux ratios < 2, suggesting that it is not likely a substrate of an efflux transporter. Collectively, these in vitro data may account for the dramatic increase in brain exposure over plasma as noted above. Pre-clinical efficacy studies showed that CM93 is more effective than other EGFR-TKIs in blocking the proliferation of GBM tumor cells from both patient-derived and cultured human GBM cell lines with EGFR amplification and/or EGFRvIII mutation. In addition, CM93 administered as a single agent was able to attenuate the growth of orthotopic U251-EGFRvIII xenografts and extend the survival of tumor-bearing mice in a dose-dependent manner. Moreover, CM93 inhibited EGFR phosphorylation in GBM tumors derived from a novel genetically-engineered mouse (GEM) model of GBM with EGFRvIII expression both in vitro and in vivo. CM93 also extended the survival of mice bearing orthotopic allografts of GBM. Notably, mice maintained stable body weight during treatments with increasing doses of CM93 up to 75 mg/kg per day. Together, these data suggest that CM93 is a potential EGFR-TKI well suited for the treatment of adult GBM with mutant EGFR.

cancer biology↗

bioRxiv2019

Development and Optimisation of a Defined High Cell Density Yeast Medium

Saccharomyces cerevisiae cells grown in a small volume of a defined media neither reach the desired cell density nor grow at a fast enough rate to scale down the volume and increase the sample number of classical biochemical assays, as the detection limit of the readout often requires a high number of cells as an input. To ameliorate this problem, we developed and optimised a new high cell density (HCD) medium for S. cerevisiae. Starting from a widely-used synthetic medium composition, we systematically varied the concentrations of all components without the addition of other compounds. We used response surface methodology (RSM) to develop and optimise the five components of the medium: glucose, yeast nitrogen base, amino acids, mono-sodium glutamate and inositol. We monitored growth, cell number and cell size to ensure that the optimisation was towards a greater density of cells rather than just towards an increase in biomass (i.e larger cells). Cells grown in the final medium, HCD, exhibit growth more similar to the complex medium YPD than to the synthetic medium SD, while the final cell density prior to the diauxic shift is increased about three- and tenfold, respectively. We found normal cell-cycle behaviour throughout the growth phases by monitoring DNA content and protein expression using fluorescent reporters. We also ensured that HCD media could be used with a variety of strains and that they allow selection for all common yeast auxotrophic markers.

microbiology↗