Periodic Reporting for period 2 - Magicbullet Reloaded (Small-Molecule Drug Conjugates for Targeted Delivery in Tumor Therapy)
Berichtszeitraum: 2021-11-01 bis 2024-04-30
Despite the continuing development of new and more efficient treatments, cancer remains the second cause of premature death worldwide. Multi-faceted interdisciplinary research efforts in industry and academia on different aspects of cancer have provided a knowledge basis for the development of novel therapeutic approaches.
Paul Ehrlich, Nobel laureate in Physiology of 1908, had the early vision that a compound could be made to selectively target a disease-causing organism or tumour. The European Training Network (ETN) Magicbullet::Reloaded refers to Ehrlich's visionary concept and focused on the development of new-generation anticancer agents, capable of selectively eradicating cancer cells, while sparing healthy tissues. The consortium thus addressed important societal challenges and specific concerns shared by citizens in Europe in terms of health and well-being. Efforts are required to maintain effective healthcare for all ages. New, efficient and sustainable therapies against complex diseases, such as cancer, and stratified and/or personalised treatments need to be developed. The ETN Magicbullet::Reloaded brought together academic and industrial partners, both larger companies and SME, from six different countries. There is expertise in Organic Chemistry, Peptide Chemistry, Medicinal Chemistry, Drug Discovery, Biochemistry, Pharmacology and Cell Biology. Fifteen Early-Stage Researchers, recruited for the project, were trained in an interdisciplinary context for a future employment in pharmaceutical research and development.
In targeted tumour therapy, an antitumour agent should be delivered specifically at the site of disease. Such an ideal therapeutic agent would be a “magic bullet” that is directed only to the site of pathology, because it is carrying a chemical “address label”. Thus, higher treatment efficiency is to be expected without adverse side effects observed in classical tumour therapy.
Several antibody-drug conjugates (ADC) have been approved during the past two decades. On its way to the tumour, an antitumour agent needs to cross barriers in the body. Once arrived at a solid tumour, it should be capable to penetrate into the tumour tissue. However, ADC often are compromised by insufficient tissue penetration. Conversely, small molecule-drug conjugates (SMDC) easily are able to diffuse into tumour tissue because of the smaller size.
The ETN Magicbullet::Reloaded consortium carried out the synthesis and biological evaluation of small molecule-drug conjugates (SMDC) and antibody-drug conjugates (ADC). The conjugates comprise a tumour-targeting unit (e.g. a small molecule, a peptide, or an antibody) and an anticancer drug (i.e. a cytotoxic or immune-stimulating agent, also called payload), connected by a suitable linker-spacer system. Binding of the targeting unit to tumour-associated receptors promotes the accumulation of the payload at the tumour site. The linker-spacer system is fundamental for the release of the drug in its active form at the tumour site, while premature drug release in the blood stream has to be prevented. Focus was also being placed on drugs capable to stimulate tumour immune responses and overcome resistance to immuno-therapy.
Paul Ehrlich, Nobel laureate in Physiology of 1908, had the early vision that a compound could be made to selectively target a disease-causing organism or tumour. The European Training Network (ETN) Magicbullet::Reloaded refers to Ehrlich's visionary concept and focused on the development of new-generation anticancer agents, capable of selectively eradicating cancer cells, while sparing healthy tissues. The consortium thus addressed important societal challenges and specific concerns shared by citizens in Europe in terms of health and well-being. Efforts are required to maintain effective healthcare for all ages. New, efficient and sustainable therapies against complex diseases, such as cancer, and stratified and/or personalised treatments need to be developed. The ETN Magicbullet::Reloaded brought together academic and industrial partners, both larger companies and SME, from six different countries. There is expertise in Organic Chemistry, Peptide Chemistry, Medicinal Chemistry, Drug Discovery, Biochemistry, Pharmacology and Cell Biology. Fifteen Early-Stage Researchers, recruited for the project, were trained in an interdisciplinary context for a future employment in pharmaceutical research and development.
In targeted tumour therapy, an antitumour agent should be delivered specifically at the site of disease. Such an ideal therapeutic agent would be a “magic bullet” that is directed only to the site of pathology, because it is carrying a chemical “address label”. Thus, higher treatment efficiency is to be expected without adverse side effects observed in classical tumour therapy.
Several antibody-drug conjugates (ADC) have been approved during the past two decades. On its way to the tumour, an antitumour agent needs to cross barriers in the body. Once arrived at a solid tumour, it should be capable to penetrate into the tumour tissue. However, ADC often are compromised by insufficient tissue penetration. Conversely, small molecule-drug conjugates (SMDC) easily are able to diffuse into tumour tissue because of the smaller size.
The ETN Magicbullet::Reloaded consortium carried out the synthesis and biological evaluation of small molecule-drug conjugates (SMDC) and antibody-drug conjugates (ADC). The conjugates comprise a tumour-targeting unit (e.g. a small molecule, a peptide, or an antibody) and an anticancer drug (i.e. a cytotoxic or immune-stimulating agent, also called payload), connected by a suitable linker-spacer system. Binding of the targeting unit to tumour-associated receptors promotes the accumulation of the payload at the tumour site. The linker-spacer system is fundamental for the release of the drug in its active form at the tumour site, while premature drug release in the blood stream has to be prevented. Focus was also being placed on drugs capable to stimulate tumour immune responses and overcome resistance to immuno-therapy.
A novel strategy to produce both DNA-encoded chemical libraries of both small molecules and peptides was developed to accelerate the discovery of novel ligands for tumour-associated antigens. Several arrays of small molecule-drug conjugates (including peptide-drug conjugates) were synthesized. They are directed against a panel of tumour-associated targets like hormone receptors, carbonic anhydrase IX, fibroblast activation protein, folate receptor, prostate specific membrane antigen, EDB, and integrins. Some conjugates were also equipped with immunomodulatory agents, specifically targeting the tumour suppressor protein p53.
Tumour cell lines that are suitable for testing novel conjugates with respect to cytotoxicity and targeting, but also immune response stimulation against the tumour, were identified and characterized. Primary tumour cells and adjacent lung tissue were collected to characterize tumour-associated macrophages (TAM), which are linked to poor prognosis. Isolated TAMs were compared to an identified macrophage marker panel.
Pharmacokinetics, in particular plasma stability, cellular uptake, antitumour activity, and payload release in tumour cells, was studied in biochemical assays and using high-end mass spectrometric techniques. Efficacy, plasma stability, and tissue penetration were shown to be improved by liposome formulations, multivalent display on dextran matrices, conjugation with antibody fragments, or cell-penetrating peptides. Research on protein mediated signalling in brain tumour cells provided deeper understanding about its function associated with tumour progression. The results were published in 18 peer-reviewed publications in highly renowned journals such as Science, PNAS or Chemical Science.
Tumour cell lines that are suitable for testing novel conjugates with respect to cytotoxicity and targeting, but also immune response stimulation against the tumour, were identified and characterized. Primary tumour cells and adjacent lung tissue were collected to characterize tumour-associated macrophages (TAM), which are linked to poor prognosis. Isolated TAMs were compared to an identified macrophage marker panel.
Pharmacokinetics, in particular plasma stability, cellular uptake, antitumour activity, and payload release in tumour cells, was studied in biochemical assays and using high-end mass spectrometric techniques. Efficacy, plasma stability, and tissue penetration were shown to be improved by liposome formulations, multivalent display on dextran matrices, conjugation with antibody fragments, or cell-penetrating peptides. Research on protein mediated signalling in brain tumour cells provided deeper understanding about its function associated with tumour progression. The results were published in 18 peer-reviewed publications in highly renowned journals such as Science, PNAS or Chemical Science.
DNA-encoded libraries have been developed that will lead to the discovery of new ligands against relevant tumour-associated proteins. Several ligands have been validated, optimized and some of them converted into therapeutically applicable small molecule-drug conjugates. Small molecule-drug conjugates and peptide-drug conjugates are on their way to provide new agents for personalized tumour therapy with less side effects improving the patients’ quality of life. Selectivity and potency of anti-tumour drugs have been enhanced. Some SMDC even have pan-tumoural potential. The new anti-FAP SMDCs are targeting the tumour microenvironment and are effective in releasing high and stable amounts of drug payload. Reproducible and reliable techniques for the pharmaceutical analysis of small molecule- and peptide-drug conjugates have been established to achieve faster turnout rates for potentially life changing drugs for cancer therapy. Novel targets are in discovery for drug development to increase therapeutic options for patients e.g. with non-small cell lung cancer. Innovative agents stimulating immune response have been developed for labelling tumour cells to let the immune system specifically eradicate them. Pharmacokinetics of the conjugates were modulated in different approaches: There is evidence that targeted liposomes bearing chemotherapeutic agents represent a new treatment generation for cancer patients. Small antibodies designed for better penetration and diffusion into tumours, and the combination of them with potent cytotoxic drugs will increase the treatment efficiency. Hybrid systems have been obtained from small molecule-drug conjugates and protein (antibody) fragments to improve penetration into solid tumours. The potency of our peptide-drug conjugates can be further increased e.g. by attachment of multiple copies to dextran.