Angiogenesis, the growth of new blood vessels, contributes to major pathologies such as blinding ocular disease, inflammation and cancer. Blocking angiogenesis has therefore become a major field of research and an attractive therapeutic strategy. Current anti-angiogenic therapies focus on blockade of pro-angiogenic factors (such as VEGF). However, in cancer, insufficient efficacy, resistance and toxicity restrict the success of anti-VEGF agents. There is thus an urgent unmet need for novel anti-angiogenic strategies. In our corresponding ERC research project, we developed an entirely novel anti-angiogenic concept and strategy, based on targeting key metabolic pathways in endothelial cells (ECs). In particular, we identified a key glycolytic regulator, 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3), as a promising target for anti-angiogenic therapy. In this proof of concept (PoC) project, we proposed to develop lead small molecule compounds to block this key glycolytic enzyme.
At present, PFKFB3 inhibitors (such as 3PO, PFK15, PFK158 and YN1) are merely research tools. Clinically applicable, orally available small molecule compounds that efficiently and specifically inhibit PFKFB3’s kinase activity are non-existing. Developing a specific and potent PFKFB3 blocker that can be administered orally would thus represent a substantial advancement and create novel therapeutic opportunities. The identification of new lead compounds thus holds all the potential to create far-reaching economic and social benefit. Indeed, novel PFKFB3 inhibitors will be widely applicable, in cancer (primary focus) but also in other diseases with an angiogenesis component such as ocular diseases, inflammatory disorders, etc.
To give this project the necessary weight and momentum, we are collaborating with VIB Discovery Sciences (VIB DS), an early drug discovery team of industry-recruited experts, with SOM-BioTech, a drug-repurposing company (Barcelona, Spain) and with a well-known academic drug discovery team at Centro Nacional de Investigaciones Oncológicas (CNIO, Madrid, Spain), with complementary expertise to drive the necessary medicinal chemistry (med-chem) activities (Experimental Therapeutics Program, ETP). During the course of this PoC high-throughput compound screens, rational drug design as well as drug-repurposing efforts were undertaken to identify hit compounds with nanomolar (nM) range inhibitory effect on PFKFB3’s kinase activity in an in vitro assay. These compounds are currently being evaluated in ECs for their effects on PFKFB3-driven glycolysis, proliferation and viability. Of note, we have also set up a cellular ‘target engagement’ assay required to evaluate the specificity of the identified hit compounds. This involves the technically demanding mass-spectrometric identification and quantification of PFKFB3’s kinase end-product fructose-2,6-bisphosphate in ECs treated with the compounds.
In conclusion, during this 18-month PoC project, we have made considerable progress in the identification of novel PFKFB3 inhibiting compounds. With evaluation for biological action and target engagement in ECs ongoing, we hope to bring new, first-in-class PFKFB3 inhibitors to interested pharmaceutical partners in the nearest future, with the ultimate aim of seeing such compounds entering clinical trials.
