FLUORODRUGS has covered two main scientific goals:
1. There is established evidence that the immune system, and in particular macrophages subpopulations, play pivotal roles in the progression of cancer. However, the role of these immune cells in the tumour microenvironment remains unclear, mainly because of the lack of technologies to target these cells in vivo. In FLUORODRUGS we have generated new fluorophores to specifically target immune cells (e.g. macrophages, T cells) and tumour associated biomarkers (e.g. glucose, lactate, pH gradients), creating new opportunities for the study of cancer progression. To achieve this, we have used three main fluorescent scaffolds for the development of activatable fluorophores: 1) boron-dipyrromethene (BODIPY), 2) nitro-benzoxadiazole (NBD) 3) heptamethine cyanine (Cy7). Furthermore, we have tuned the optical properties of our novel probes covering a region of the electromagnetic spectrum ranging from the visible to the near infrared (NIR), allowing multicolour imaging and deeper penetration in tissues.
First, we have developed a library of tricarbocyanine N-triazoles as a new family of bright, photostable and cell-permeable NIR fluorophores and discovered that CIR38M can label small populations of T cells with high sensitivity (i.e. around 4000 cells) and with cells being detectable in vivo over 7 days post-transfer. This opens multiple opportunities for in situ NIR imaging of immunotherapy efficacy and disease progression in preclinical and clinical research. This work has been published in Chemical Science, a top journal in multidisciplinary chemistry (IF>9) and issued a priority file (GB.P195477-2018) which is been studied by Ithera Medical and Biolegend for collaboration and commercial exploitation.
Secondly, in FLUORODRUGS we have developed SCOTfluors as novel small-sized multicolored fluorophores for real-time tracking of metabolites in vivo and for the acquisition of metabolic profiles from human cancer cells of variable origin, based on the nitrobenzodioxazole (NBD) scaffold (Figure 2). The transport and trafficking of metabolites are essential for the correct functioning of live cells. However, in situ metabolic imaging studies are hampered by the lack of fluorescent chemical structures that allow direct monitoring of small metabolites under physiological conditions. We have used SCOTfluors to image different metabolites in vitro (e.g. sphingosine, lactate) and in vivo (e.g. glucose). The tunability and versatility of SCOTfluors will enable non-invasive imaging studies of small metabolites in vivo that could not be performed with conventional fluorophores. This work has been published in Angewandte Chemie, a top journal in multidisciplinary chemistry and protected under a priority file.
Finally, we have derivatised Phagogreen, a specific probe for phagocytic macrophages previously reported in JACS by Vendrell group, to produce a NIR library of α-aminoamides. We have performed a high-throughput screening of these new compounds against inflammatory bone marrow-derived macrophages (BMDM) and identified Phagored as selective probe for inflammatory BMDM. Phagored is being studied as a potential biomarker for early diagnosis of colorectal carcinoma, which will provide valuable information for patient stratification, allowing endoscopists to establish an optical diagnosis.
2. Theranostic is a new field of medicine which uses specific biological pathways in patients, to acquire diagnostic images and also to deliver a therapeutic drug. Theranostic agents provide a transition from conventional medicine to a personalised and precision medicine approach, allowing diagnosis, drug delivery and treatment response monitoring from a single agent.
In FLUORODRUGS we have developed new chemical strategies to prepare derivatives that combine our activatable fluorophores to small drugs (e.g. doxorubicin) to create new theranostic agents (Figure 3) for highly innovative studies of dual imaging and therapy studies of macrophages (e.g. study of specific modulation of macrophages in vivo). We have demonstrated the applicability of these conjugates in vivo using regeneration models to image and deplete phagocytic M1 macrophages. This platform will accelerate the development of chemical immunomodulatory agents as subpopulations-specific targeted therapies for immune-related disorders. This work has been published in ACS Central Science, a top journal in multidisciplinary chemistry (IF>11) and a follow-up article in ACS Biochemistry (IF=3).
Finally, we have labelled our probes with chemokines in order to enhance the selectivity and specificity in vitro and in vivo. Chemokines are small signalling proteins (60-100 amino acids) whose main function is to regulate cell trafficking. We have developed the first CCL2 tagged with a pH-activatable BODIPY fluorophore which enables specific visualization of pro-inflammatory CCR2+ macrophage subpopulations in vivo. We are applying CCL2-Phagogreen in relevant in vivo models of lung metastasis to unravel the role of CCR2+ macrophages, which are related with malignancy progression in collaboration with Prof. Pollard (University of Edinburgh, UK). This methodology is applicable to other activatable fluorescent probes and chemokines to target cell subpopulations specifically and interrogate cell functions in disease progression with enhanced specificity.
This MSCA has been disseminated to reach the academic/scientific community (i.e. articles, conferences) and the public in general (i.e. public seminars, Science Festival), ensuring maxima diffusion of the discoveries in FLUORODRUGS.
