Two is better than one
A fundamentally new strategy for targeted delivery of anticancer drugs has been developed
The press service of the Russian National Fund
An international group of scientists has developed a new strategy for targeted delivery of compounds for the treatment and diagnosis of cancer diseases, which can significantly improve both the effectiveness of diagnosis and treatment of aggressive metastatic tumors. The researchers created two "weapons" that hit the same target, and thereby reduced the concentration of active substances by 1000 times to achieve the same therapeutic effect as with standard treatment with one drug. The development was tested on animals. The results of the study are published in the journal ACS Nano. The work is supported by grants The Presidential Program of the Russian Science Foundation (RNF).
"By ensuring effective delivery of therapeutic agents to the tumor area, the technology of double targeting of a single target – a protein on the surface of cancer cells – can significantly reduce the effective concentration of the drug to achieve the same effect. It is expected that such a dose reduction will minimize side effects, which can be very serious when using non-specific chemotherapeutic drugs that limit the choice of subsequent treatment plans. On the other hand, the use of our developments for targeted delivery leads to a low immune response of the body, which will allow, if necessary, to repeat the course of therapy. In addition, the proposed technology offers a way for highly effective treatment within a very short period of time, which is very important for preventing metastases in rapidly developing neoplasms," comments Victoria Shipunova, the first author of the article, project manager for the grant of the Russian Academy of Sciences, Candidate of Biological Sciences, senior researcher Laboratories of Molecular Immunology Institute of Bioorganic Chemistry named after M.M. Shemyakin and Yu.A. Ovchinnikov RAS (IBH RAS, Moscow).
According to the Ministry of Health, there are now 3.7 million people living in Russia with some kind of cancer (about 2.6 thousand cases per 100 thousand population). Oncological diseases – one of the most serious problems of biology and medicine – require diagnosis and intervention at the earliest stages of development, which is especially critical in the case of the development of aggressive metastatic tumors. To combat these diseases, chemotherapeutic drugs of a wide spectrum are traditionally used (not aimed only at the tumor), such as doxorubicin, paclitaxel, methotrexate and others, which lead to a number of serious side effects. To reduce systemic toxicity and increase therapeutic efficacy, various types of combination therapy are often used, for example, combining chemotherapy, radiation therapy, cell therapy and/or immunotherapy.
In addition, the effectiveness of treatment can be improved by using nanoparticles of different nature. They represent an ideal platform for delivering therapeutic compounds directly to tumor cells. To do this, the surface of the nanoparticles is covered with recognition molecules that bring the nanoparticles exactly "on target" and minimize side effects for the body.
A promising approach for cancer theranostics (diagnosis and therapy using a single compound) is a combination of immunotherapy and targeted delivery of chemotherapeutic compounds, for example, using nanoparticles. However, this approach today demonstrates only limited success due to a number of problems, such as the low therapeutic index of traditional chemotherapy, the absence of a wide range of cancer markers on the cell surface and other factors.
"In the published work, we have developed a strategy of synergistic combined targeted immuno/chemotherapy: we target drugs at different sites of the same HER2 cancer marker receptor on the cell surface. HER2 is a clinically significant cancer marker, an increased amount of which on the cell surface is often associated with resistance to chemotherapy, high metastasis and poor prognosis," notes Victoria Shipunova.
Scientists have targeted the tumor with two components at once. Firstly, nanoparticles of polylactide-co-glycolide – a copolymer of lactic and glycolic acids, that is, a composite of substances that exist in the human body. The nanoparticle balls were "filled" with the chemotherapy drug doxorubicin, as well as an addressable polypeptide – an affine molecule that allows you to see what happens in the body after the drug is launched.
As the second component, a fragment of a toxin from Pseudomonas aeruginosa associated with another targeted polypeptide recognizing the HER2 cancer marker was used. This polypeptide, darpin9.29, binds another site of the HER2 receptor without competing for the binding site with affine molecules.
In their work, scientists for the first time used targeted scaffold polypeptides to target one cancer marker – HER2. Scaffold polypeptides are a new popular class of targeting compounds that are used instead of traditional full–size antibodies. They are smaller, less likely to cause an undesirable immune response, are highly soluble and stable under extreme conditions, and are also much easier and cheaper to synthesize in bioreactors, which is important for their further mass use in biomedicine.
"The use of two targeted superstructures made it possible to reduce the concentration of active substances by 1000 times to achieve the same therapeutic effect. Moreover, the combination of these drugs acts synergistically, that is, one substance significantly enhances the effect of the other. This is especially surprising and unexpected, since both drugs affect only one cellular receptor. This synergy allowed us to significantly enhance the effectiveness of therapy for HER2-positive tumors in animals and completely prevent the appearance of metastases," says Victoria Shipunova.
In the work, scientists used immunodeficient mice that do not have a thymus to test their developments, which leads to a low number of protective cells of the body – T-lymphocytes. Such mice were injected with human cancer cells carrying the human cancer marker HER2, and the lack of sufficient protective forces of the mice's immunity allowed these cells to "take root" in the mouse body and form a metastatic tumor. Accordingly, the researchers obtained a convenient model for preclinical studies of malignant growth – tumors resembling human tumors formed in mice and responding to treatment in the same way as human cancer cells would react.
Since the developed drugs are different in origin and meaning, they are excreted from the body in different ways: nanoparticles – through the liver or spleen, proteins – through the kidneys. Thus, by combining therapeutic agents and reducing their concentration, it is possible to minimize the impact on organs (by "redistributing" the overall heavy load, for example, on the liver, between all organs in a much smaller dose) and drastically reducing side effects, which is very important for the development of effective oncoteranostics strategies.
"The developed dual–targeting strategy, implying "two agents – one receptor" is a big step towards the development of effective methods for the treatment of aggressive tumors. This strategy can be extended to other combined treatment methods and antitumor targets," believes Sergey Deev, Doctor of Biological Sciences, Professor, Academician of the Russian Academy of Sciences, head of the research, head of the Laboratory of Molecular Immunology, where the main part of the work was performed.
The research was also carried out in collaboration with the Engineering Physics Institute of Biomedicine of the National Research Institute of MEPhI and the Institute of Lasers, Photonics and Biophotonics of the State University of New York at Buffalo (USA). Experiments on the biovisualization of tumors in laboratory mice were carried out using the equipment of the CCP of the IBH RAS.
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