Evaluation of TK1 targeting carboranyl thymidine analogs as potential delivery agents for neutron capture therapy of brain tumors

The Dawn of a New Era: Tumor-Targeting Boron Agents for Neutron Capture Therapy

Cancer is widely recognized as one of the most devastating diseases, necessitating the development of intelligent diagnostic techniques, targeted treatments, and early prognosis evaluation to ensure effective and personalized therapy. Conventional treatments, unfortunately, suffer from limitations and an increased risk of severe complications. In light of these challenges, boron neutron capture therapy (BNCT) has emerged as a promising approach for cancer treatment with unprecedented precision to selectively eliminate tumor cells. The distinctive and promising characteristics of BNCT hold the potential to revolutionize the field of oncology. However, the clinical application and advancement of BNCT technology face significant hindrance due to the inherent flaws and limited availability of current clinical drugs, which pose substantial obstacles to the practical implementation and continued progress of BNCT. Consequently, there is an urgent need to develop efficient boron agents with higher boron content and specific tumor-targeting properties. Researchers aim to address this need by integrating tumor-targeting strategies with BNCT, with the ultimate goal of establishing BNCT as an effective, readily available, and cutting-edge treatment modality for cancer. This review delves into the recent advancements in integrating tumor-targeting strategies with BNCT, focusing on the progress made in developing boron agents specifically designed for BNCT. By exploring the current state of BNCT and emphasizing the prospects of tumor-targeting boron agents, this review provides a comprehensive overview of the advancements in BNCT and highlights its potential as a transformative treatment option for cancer.

Boron Neutron Capture Therapy: Clinical Application and Research Progress

Boron neutron capture therapy (BNCT) is a binary modality that is used to treat a variety of malignancies, using neutrons to irradiate boron-10 (¹⁰B) nuclei that have entered tumor cells to produce highly linear energy transfer (LET) alpha particles and recoil ⁷Li nuclei (¹⁰B [n, α] ⁷Li). Therefore, the most important part in BNCT is to selectively deliver a large number of ¹⁰B to tumor cells and only a small amount to normal tissue. So far, BNCT has been used in more than 2000 cases worldwide, and the efficacy of BNCT in the treatment of head and neck cancer, malignant meningioma, melanoma and hepatocellular carcinoma has been confirmed. We collected and collated clinical studies of second-generation boron delivery agents. The combination of different drugs, the mode of administration, and the combination of multiple treatments have an important impact on patient survival. We summarized the critical issues that must be addressed, with the hope that the next generation of boron delivery agents will overcome these challenges.

Nanocząstki o wysokiej zawartości boru jako potencjalne nośniki w terapii borowo-neutronowej

Podstawą terapii borowo-neutronowej (boron neutron capture therapy, BNCT) jest selektywne dostarczenie boru do komórek nowotworowych, a następnie napromienienie zmienionego chorobowo miejsca wiązką neutronów. W wyniku tego procesu dochodzi do rozszczepienia jądra izotopu 10B, co powoduje uwolnienie energii niszczącej komórki nowotworowe. Mimo że badania związane z BNCT trwają od lat 50. XX wieku, pozostaje ona wciąż terapią eksperymentalną. Jest to związane m.in. z brakiem nośników umożliwiających szybkie i skuteczne wprowadzanie 10B do środowiska nowotworu. Tak więc często podnoszonym zagadnieniem i jednym z głównych wyzwań dla rozwoju BNCT, jest poszukiwanie selektywnych związków dostarczających wymaganą ilość tego pierwiastka. Istotnym aspektem są badania nad nanometrycznymi strukturami, takimi jak liposomy zawierające związki bogate w bor lub nieorganiczne nanocząstki – węglik boru czy azotek boru. Ze względu na dużą zawartość boru oraz możliwość modyfikacji powierzchni tych nanocząstek, mogą się one okazać wyjątkowo atrakcyjnym narzędziem w celowanej BNCT. Równie ważnym problemem tej terapii jest opracowanie precyzyjnych powiązań między źródłem neutronów, specyfiką wiązki a rodzajem zastosowanego nośnika. W artykule wskazujemy na wysoki potencjał związków bogatych w bor jako nośników w celowanej terapii borowo-neutronowej.

Boron neutron capture therapy: Current status and future perspectives

The development of new accelerators has given a new impetus to the development of new drugs and treatment technologies using boron neutron capture therapy (BNCT). We analyzed the current status and future directions of BNCT for cancer treatment, as well as the main issues related to its introduction. This review highlights the principles of BNCT and the key milestones in its development: new boron delivery drugs and different types of charged particle accelerators are described; several important aspects of BNCT implementation are discussed. BCNT could be used alone or in combination with chemotherapy and radiotherapy, and it is evaluated in light of the outlined issues. For the speedy implementation of BCNT in medical practice, it is necessary to develop more selective boron delivery agents and to generate an epithermal neutron beam with definite characteristics. Pharmacological companies and research laboratories should have access to accelerators for large-scale screening of new, more specific boron delivery agents.

The Current Status and Perspectives of Delivery Strategy for Boron-based Drugs

Boron-containing compounds are essential micronutrients for animals and plants despite their low-level natural occurrence. They can strengthen the cell walls of the plants and they play important role in supporting bone health. However, surprisingly, boron-containing compounds are seldom found in pharmaceutical drugs. In fact, there are no inherent disadvantages reported so far in terms of the incorporation of boron into medicines. Indeed, drugs based on boron-containing compounds, such as tavaborole (marked name Kerydin) and bortezomib (trade name Velcade) have been investigated and they are used in clinical treatment. In addition, following the advanced development of boron neutron capture therapy and a new emerging proton boron fusion therapy, more boron-containing medicinals are to be expected. This review discusses the current status and perspectives of delivery strategy for boron-containing drugs.

Boron delivery agents for neutron capture therapy of cancer

Boron neutron capture therapy (BNCT) is a binary radiotherapeutic modality based on the nuclear capture and fission reactions that occur when the stable isotope, boron-10, is irradiated with neutrons to produce high energy alpha particles. This review will focus on tumor-targeting boron delivery agents that are an essential component of this binary system. Two low molecular weight boron-containing drugs currently are being used clinically, boronophenylalanine (BPA) and sodium borocaptate (BSH). Although they are far from being ideal, their therapeutic efficacy has been demonstrated in patients with high grade gliomas, recurrent tumors of the head and neck region, and a much smaller number with cutaneous and extra-cutaneous melanomas. Because of their limitations, great effort has been expended over the past 40 years to develop new boron delivery agents that have more favorable biodistribution and uptake for clinical use. These include boron-containing porphyrins, amino acids, polyamines, nucleosides, peptides, monoclonal antibodies, liposomes, nanoparticles of various types, boron cluster compounds and co-polymers. Currently, however, none of these have reached the stage where there is enough convincing data to warrant clinical biodistribution studies. Therefore, at present the best way to further improve the clinical efficacy of BNCT would be to optimize the dosing paradigms and delivery of BPA and BSH, either alone or in combination, with the hope that future research will identify new and better boron delivery agents for clinical use.