Small Molecules and Immunotherapy Agents for Enhancing Radiotherapy in Glioblastoma

A novel high-risk model identified by epithelial-mesenchymal transition predicts prognosis and radioresistance in rectal cancer

Many studies have shown that tumor cells that survive radiotherapy are more likely to metastasize, but the underlying mechanism remains unclear. Here we aimed to identify epithelial-mesenchymal transition (EMT)-related key genes, which associated with prognosis and radiosensitivity in rectal cancer. First, we obtained differentially expressed genes by analyzing the RNA expression profiles of rectal cancer retrieved from The Cancer Genome Atlas database, EMT-related genes, and radiotherapy-related databases, respectively. Then, Lasso and Cox regression analyses were used to establish an EMT-related prognosis model (EMTPM) based on the identified independent protective factor Fibulin5 (FBLN5) and independent risk gene EHMT2. The high-EMTPM group exhibited significantly poorer prognosis. Then, we evaluated the signature in an external clinical validation cohort. Through in vivo experiments, we further demonstrated that EMTPM effectively distinguishes radioresistant from radiosensitive patients with rectal cancer. Moreover, individuals in the high-EMTPM group showed increased expression of immune checkpoints compared to their counterparts. Finally, pan-cancer analysis of the EMTPM model also indicated its potential for predicting the prognosis of lung squamous cell carcinoma and breast cancer patients undergoing radiotherapy. In summary, we established a novel predictive model for rectal cancer prognosis and radioresistance based on FBLN5 and EHMT2 expressions, and suggested that immune microenvironment may be involved in the process of radioresistance. This predictive model could be used to select management strategies for rectal cancer.

Additive Value of Magnetic Resonance Simulation Before Chemoradiation in Evaluating Treatment Response and Pseudoprogression in High-Grade Gliomas

PURPOSE

A dedicated magnetic resonance imaging simulation (MRsim) for radiation treatment (RT) planning in patients with high-grade glioma (HGG) can detect early radiologic changes, including tumor progression after surgery and before standard of care chemoradiation. This study aimed to determine the effect of using postoperative magnetic resonance imaging (MRI) versus MRsim as the baseline for response assessment and reporting pseudoprogression on follow-up imaging at 1 month (FU1) after chemoradiation.

METHODS AND MATERIALS

Histologically confirmed patients with HGG were planned for 6 weeks of RT in a prospective study for adaptive RT planning. All patients underwent postoperative MRI, MRsim, and follow-up MRI scans every 2 to 3 months. Tumor response was assessed by 3 independent blinded reviewers using Response Assessment in Neuro-Oncology criteria when baseline was either postoperative MRI or MRsim. Interobserver agreement was calculated using Light's kappa.

RESULTS

Thirty patients (median age, 60.5 years; IQR, 54.5-66.3) were included. Median interval between surgery and RT was 34 days (IQR, 27-41). Response assessment at FU1 differed in 17 patients (57%) when the baseline was postoperative MRI versus MRsim, including true progression versus partial response or stable disease in 11 (37%) and stable disease versus partial response in 6 (20%) patients. True progression was reported in 19 patients (63.3%) on FU1 when the baseline was postoperative MRI versus 8 patients (26.7%) when the baseline was MRsim (P = .004). Pseudoprogression was observed at FU1 in 12 (40%) versus 4 (13%) patients, when the baseline was postoperative MRI versus MRsim (P = .019). Interobserver agreement between observers was moderate (κ = 0.579; P < .001).

CONCLUSIONS

Our study demonstrates the value of acquiring an updated MR closer to RT in patients with HGG to improve response assessment, and accuracy in evaluation of pseudoprogression even at the early time point of first follow-up after RT. Earlier identification of patients with true progression would enable more timely salvage treatments including potential clinical trial enrollment to improve patient outcomes.

Nanoradiosensitizers in glioblastoma treatment: recent advances and future perspectives

Glioblastoma (GBM), a highly invasive type of brain tumor located within the central nervous system, manifests a median survival time of merely 14.6 months. Radiotherapy kills tumor cells through focused high-energy radiation and has become a crucial treatment strategy for GBM, especially in cases where surgical resection is not viable. However, the presence of radioresistant tumor cells limits its clinical effectiveness. Radioresistance is a key factor of treatment failure, prompting the development of various therapeutic strategies to overcome this challenge. With the rapid development of nanomedicine, nanoradiosensitizers provide a novel approach to enhancing the effectiveness of radiotherapy. In this review, we discuss the reasons behind GBM radio-resistance and the mechanisms of radiotherapy sensitization. Then we summarize the primary types of nanoradiosensitizers and recent progress in their application for the radiosensitization of GBM. Finally, we elucidate the factors influencing their practical implementation, along with the challenges and promising prospects associated with multifunctional nanoradiosensitizers.

Evaluating deposited radiation energy amount and collision quantities of small-molecule radiosensitizers through Monte Carlo simulations

This study investigates the photon interaction mechanism of various small molecule radiosensitizers, including Hydrogen Peroxide, Nimorazole, 5-Fluorouracil, NVX-108, and others, using the MCNP 6.3 Monte Carlo simulation code. The simulations focused on quantifying the linear attenuation coefficients, mean free path, and accumulation factors of these radiosensitizers, as well as their interactions in a simulated spherical water phantom irradiated with a 100 keV mono-energetic X-ray source. Our findings reveal significant variations in deposited energy, collision events, and mean free path among the radiosensitizers, indicating different efficacy levels in enhancing radiation therapy. Notably, NVX-108 demonstrated the highest energy deposition, suggesting its potential as a highly effective radiosensitizer. The study also examined the individual attenuation properties of these radiosensitizers against energetic photons, with NVX-108 showing the highest attenuation coefficient and a shorter mean free path, further supporting its superior potential in effective radiosensitization. It can be concluded that NVX-108 has higher interaction tendency with the energetic photons comparing other small-molecules under investigation.

Assembling Au8 clusters on surfaces of bifunctional nanoimmunomodulators for synergistically enhanced low dose radiotherapy of metastatic tumor

BACKGROUND

Radiotherapy is one of the mainstays of cancer therapy and has been used for treating 65-75% of patients with solid tumors. However, radiotherapy of tumors has two limitations: high-dose X-rays damage adjacent normal tissue and tumor metastases cannot be prevented.

RESULTS

Therefore, to overcome the two limitations of radiotherapy, a multifunctional core-shell R837/BMS@Au8 nanoparticles as a novel radiosensitizer were fabricated by assembling Au8NCs on the surface of a bifunctional nanoimmunomodulator R837/BMS nanocore using nanoprecipitation followed by electrostatic assembly. Formed R837/BMS@Au8 NP composed of R837, BMS-1, and Au8 clusters. Au8NC can enhance X-ray absorption at the tumor site to reduce X-ray dose and releases a large number of tumor-associated antigens under X-ray irradiation. With the help of immune adjuvant R837, dendritic cells can effectively process and present tumor-associated antigens to activate effector T cells, meanwhile, a small-molecule PD-L1 inhibitor BMS-1 can block PD-1/PD-L1 pathway to reactivate cytotoxic T lymphocyte, resulting in a strong systemic antitumor immune response that is beneficial for limiting tumor metastasis. According to in vivo and in vitro experiments, radioimmunotherapy based on R837/BMS@Au8 nanoparticles can increase calreticulin expression on of cancer cells, reactive oxygen species generation, and DNA breakage and decrease colony formation. The results revealed that distant tumors were 78.2% inhibited depending on radioimmunotherapy of primary tumors. Therefore, the use of a novel radiosensitizer R837/BMS@Au8 NPs realizes low-dose radiotherapy combined with immunotherapy against advanced cancer.

CONCLUSION

In conclusion, the multifunctional core-shell R837/BMS@Au8 nanoparticles as a novel radiosensitizer effectively limiting tumor metastasis and decrease X-ray dose to 1 Gy, providing an efective strategy for the construction of nanosystems with radiosensitizing function.

Radiotherapy of high-grade gliomas: dealing with a stalemate

This article discusses the studies on radiotherapy of high-grade gliomas published between January 1, 2022, and June 30, 2022, with special reference to their molecular biology basis. The focus was on advances in radioresistance, radiosensitization and the toxicity of radiotherapy treatments. In the first half of 2022, several important advances have been made in understanding resistance mechanisms in high-grade gliomas. Furthermore, the development of several radiosensitization procedures for these deadly tumors, including studies with small molecule radiosensitizers, new fractionation protocols, and new immunostimulatory agents, has progressed in both the preclinical and clinical settings, reflecting the frantic research effort in the field. However, since 2005 our research efforts fail to produce significant improvements to treatment guidelines for high-grade gliomas. Possible reasons for this stalemate and measures to overcome it are discussed.

Improving Localized Radiotherapy for Glioblastoma via Small Molecule Inhibition of KIF11

Glioblastoma, IDH-wild type (GBM) is the most common and lethal malignant primary brain tumor. Standard of care includes surgery, radiotherapy, and chemotherapy with the DNA alkylating agent temozolomide (TMZ). Despite these intensive efforts, current GBM therapy remains mainly palliative with only modest improvement achieved in overall survival. With regards to radiotherapy, GBM is ranked as one of the most radioresistant tumor types. In this study, we wanted to investigate if enriching cells in the most radiosensitive cell cycle phase, mitosis, could improve localized radiotherapy for GBM. To achieve cell cycle arrest in mitosis we used ispinesib, a small molecule inhibitor to the mitotic kinesin, KIF11. Cell culture studies validated that ispinesib radiosensitized patient-derived GBM cells. In vivo, we validated that ispinesib increased the fraction of tumor cells arrested in mitosis as well as increased apoptosis. Critical for the translation of this approach, we validated that combination therapy with ispinesib and irradiation led to the greatest increase in survival over either monotherapy alone. Our data highlight KIF11 inhibition in combination with radiotherapy as a new combinatorial approach that reduces the overall radioresistance of GBM and which can readily be moved into clinical trials.

Natural Products Targeting Hsp90 for a Concurrent Strategy in Glioblastoma and Neurodegeneration

Glioblastoma multiforme (GBM) is one of the most common aggressive, resistant, and invasive primary brain tumors that share neurodegenerative actions, resembling many neurodegenerative diseases. Although multiple conventional approaches, including chemoradiation, are more frequent in GBM therapy, these approaches are ineffective in extending the mean survival rate and are associated with various side effects, including neurodegeneration. This review proposes an alternative strategy for managing GBM and neurodegeneration by targeting heat shock protein 90 (Hsp90). Hsp90 is a well-known molecular chaperone that plays essential roles in maintaining and stabilizing protein folding to degradation in protein homeostasis and modulates signaling in cancer and neurodegeneration by regulating many client protein substrates. The therapeutic benefits of Hsp90 inhibition are well-known for several malignancies, and recent evidence highlights that Hsp90 inhibitors potentially inhibit the aggressiveness of GBM, increasing the sensitivity of conventional treatment and providing neuroprotection in various neurodegenerative diseases. Herein, the overview of Hsp90 modulation in GBM and neurodegeneration progress has been discussed with a summary of recent outcomes on Hsp90 inhibition in various GBM models and neurodegeneration. Particular emphasis is also given to natural Hsp90 inhibitors that have been evidenced to show dual protection in both GBM and neurodegeneration.