HER-2-targeted boron neutron capture therapy using an antibody-conjugated boron nitride nanotube/β-1,3-glucan complex

Extracellular Vesicles Comprising Carborane Prepared by a Host Exchanging Reaction as a Boron Carrier for Boron Neutron Capture Therapy

With their low immunogenicity and excellent deliverability, extracellular vesicles (EVs) are promising platforms for drug delivery systems. In this study, hydrophobic molecule loading techniques were developed via an exchange reaction based on supramolecular chemistry without using organic solvents that can induce EV disruption and harmful side effects. To demonstrate the availability of an exchanging reaction to prepare drug-loading EVs, hydrophobic boron cluster carborane (CB) was introduced to EVs (CB@EVs), which is expected as a boron agent for boron neutron capture therapy (BNCT). The exchange reaction enabled the encapsulation of CB to EVs without disrupting their structure and forming aggregates. Single-particle analysis revealed that an exchanging reaction can uniformly introduce cargo molecules to EVs, which is advantageous in formulating pharmaceuticals. The performance of CB@EVs as boron agents for BNCT was demonstrated in vitro and in vivo. Compared to L-BPA, a clinically available boron agent, and CB delivered with liposomes, CB@EV systems exhibited the highest BNCT activity in vitro due to their excellent deliverability of cargo molecules via an endocytosis-independent pathway. The system can deeply penetrate 3D cultured spheroids even in the presence of extracellular matrices. The EV-based system could efficiently accumulate in tumor tissues in tumor xenograft model mice with high selectivity, mainly via the enhanced permeation and retention effect, and the deliverability of cargo molecules to tumor tissues in vivo enhanced the therapeutic benefits of BNCT compared to the L-BPA/fructose complex. All of the features of EVs are also advantageous in establishing anticancer agent delivery platforms.

A clinician's perspective on boron neutron capture therapy: promising advances, ongoing trials, and future outlook

PURPOSE

This comprehensive review aims to provide a unique clinical perspective on the latest advances and ongoing boron neutron capture therapy (BNCT) trials for various cancers.

METHODS

We critically analyzed clinical data from BNCT trials for head and neck cancer, glioblastoma, melanoma, meningioma, breast cancer, and liver tumors. We investigated differences in tumor responses and normal tissue toxicities among trials and discussed potential contributing factors. We also identified the limitations of early BNCT trials and proposed strategies to optimize future trial design.

RESULTS

BNCT has shown promising results in treating head and neck cancer, with high response rates and improved survival in patients with recurrent disease. In glioblastoma, BNCT combined with surgery and chemotherapy has demonstrated survival benefits compared to standard treatments. BNCT has also been successfully used for recurrent high-grade meningiomas and shows potential for melanomas, extramammary Paget's disease, and liver tumors. However, differences in tumor responses and toxicities were observed among trials, potentially attributable to variations in treatment protocols, patient characteristics, and evaluation methods.

CONCLUSIONS

BNCT is a promising targeted radiotherapy for various cancers. Further optimization and well-designed randomized controlled trials are needed to establish its efficacy and safety. Future studies should focus on standardizing treatment protocols and addressing limitations to guide clinical decision-making and research priorities.

Recent progress of nano-drugs in neutron capture therapy

As a developing radiation treatment for tumors, neutron capture therapy (NCT) has less side effects and a higher efficacy than conventional radiation therapy. Drugs with specific isotopes are indispensable counterparts of NCT, as they are the indespensable part of the neutron capture reaction. Since the creation of the first and second generations of boron-containing reagents, NCT has significantly advanced. Notwithstanding, the extant NCT medications, predominantly comprised of small molecule boron medicines, have encountered challenges such monofunctionality, inadequate targeting of tumors, and hypermetabolism. There is an urgent need to promote the research and development of new types of NCT drugs. Bio-nanomaterials can be introduced into the realm of NCT, and nanotechnology can give conventional medications richer functionality and significant adaptability. This can complement the advantages of each other and is expected to develop more new drugs with less toxicity, low side effects, better tumor targeting, and high biocompatibility. In this review, we summarized the research progress of nano-drugs in NCT based on the different types and sources of isotopes used, and introduced the attempts and efforts made by relevant researchers in combining nanomaterials with NCT, hoping to provide pivotal references for promoting the development of the field of tumor radiotherapy.

Growth methodologies of boron nitride nanotubes and their neutron shielding applications: a review

This review provides a comprehensive overview of the growth methodologies and neutron shielding applications of Boron Nitride Nanotubes (BNNTs). BNNTs have garnered significant attention because of their unique combination of high thermal stability, mechanical strength, and exceptional neutron absorption properties. Synthesis methods for BNNTs, including laser ablation, thermal plasma treatment, chemical vapour deposition (CVD), and ball milling have been thoroughly examined, highlighting their mechanisms, advantages, and challenges. Each method contributes uniquely to the quality and applicability of BNNTs in terms of scalability and production efficiency. This study focused on the applications of BNNTs in neutron absorption, particularly in aerospace engineering. BNNTs have shown promising potential in enhancing the safety and longevity of space missions by providing effective radiation protection. Furthermore, their potential in medical applications, particularly in Boron Neutron Capture Therapy (BNCT) for cancer treatment, has been explored. BNCT offers a targeted approach to cancer therapy by utilizing the high boron-10 content of BNNTs for precise and localized treatment. This review also provides an outlook on the future of BNNT research, emphasizing the need for more efficient growth methods to facilitate wider adoption and commercialization. The versatility of BNNTs across various fields, from space exploration to medical science, underscores their potential as materials of significant scientific and technological importance. As research progresses, BNNTs are expected to play a pivotal role in advancing materials science and offer innovative solutions to complex challenges.

HER-2-Targeted Boron Neutron Capture Therapy with Carborane-integrated Immunoliposomes Prepared via an Exchanging Reaction

Boron neutron capture therapy (BNCT) is a promising modality for cancer treatment because of its minimal invasiveness. To maximize the therapeutic benefits of BNCT, the development of efficient platforms for the delivery of boron agents is indispensable. Here, carborane-integrated immunoliposomes were prepared via an exchanging reaction to achieve HER-2-targeted BNCT. The conjugation of an anti-HER-2 antibody to carborane-integrated liposomes successfully endowed these liposomes with targeting properties toward HER-2-overexpressing human ovarian cancer cells (SK-OV3); the resulting BNCT activity toward SK-OV3 cells obtained using the current immunoliposomal system was 14-fold that of the l-BPA/fructose complex, which is a clinically available boron agent. Moreover, the growth of spheroids treated with this system followed by thermal neutron irradiation was significantly suppressed compared with treatment with the l-BPA/fructose complex.