A preclinical model to investigate normal tissue damage following fractionated radiotherapy to the head and neck

Attention-based Vision Transformer Enables Early Detection of Radiotherapy-Induced Toxicity in Magnetic Resonance Images of a Preclinical Model

IntroductionEarly identification of patients at risk for toxicity induced by radiotherapy (RT) is essential for developing personalized treatments and mitigation plans. Preclinical models with relevant endpoints are critical for systematic evaluation of normal tissue responses. This study aims to determine whether attention-based vision transformers can classify MR images of irradiated and control mice, potentially aiding early identification of individuals at risk of developing toxicity.MethodC57BL/6J mice (n = 14) were subjected to 66 Gy of fractionated RT targeting the oral cavity, swallowing muscles, and salivary glands. A control group (n = 15) received no irradiation but was otherwise treated identically. T2-weighted MR images were obtained 3-5 days post-irradiation. Late toxicity in terms of saliva production in individual mice was assessed at day 105 after treatment. A pre-trained vision transformer model (ViT Base 16) was employed to classify the images into control and irradiated groups.ResultsThe ViT Base 16 model classified the MR images with an accuracy of 69%, with identical overall performance for control and irradiated animals. The ViT's model predictions showed a significant correlation with late toxicity (r = 0.65, p < 0.01). One of the attention maps from the ViT model highlighted the irradiated regions of the animals.ConclusionsAttention-based vision transformers using MRI have the potential to predict individuals at risk of developing early toxicity. This approach may enhance personalized treatment and follow-up strategies in head and neck cancer radiotherapy.

Mesenchymal stem cell therapies evidence in the treatment of irradiated salivary glands: A scoping review

Background

Radiotherapy is one of the main treatments for head and neck cancer; however, due to its non-selectivity the glandular tissue can be affected. This scoping review aimed to identify the evidence about mesenchymal stem cell therapies for irradiated salivary gland regeneration.

Material and Methods

Two independent reviewers performed a literature search in MEDLINE/PubMed, Scopus, and Web of Science. The inclusion criteria were: 1) studies evaluation regeneration of irradiated salivary glands by stem cell therapies (cell-based or cell-free), (2) in vivo studies.

Results

The search resulted in 13 included studies. In general, both therapies demonstrated increased salivary levels, with mucin and amylase increased and structural protection of acinar cells. The cell-free therapy based on labial glands stem cell extract demonstrated a higher number of parasympathetic nerves.

Conclusions

Stem cell therapies (cell-free and cell-based) appear promising strategies for recovering saliva production in patients presenting irradiation-induced hyposalivation, with positive results toward regeneration of the form and function of the glands. However, due to the scarcity and heterogenicity of these pre-clinical studies, it is not possible to indicate which is the more indicated therapy. Key words:Mesenchymal stem cells, extracellular vesicles, exosomes, salivary glands, stem cell biology, hyposalivation, radiotherapy.

In vivo bioluminescence tomography-guided system for pancreatic cancer radiotherapy research

Recent development of radiotherapy (RT) has heightened the use of radiation in managing pancreatic cancer. Thus, there is a need to investigate pancreatic cancer in a pre-clinical setting to advance our understanding of the role of RT. Widely-used cone-beam CT (CBCT) imaging cannot provide sufficient soft tissue contrast to guide irradiation. The pancreas is also prone to motion. Large collimation is unavoidably used for irradiation, costing normal tissue toxicity. We innovated a bioluminescence tomography (BLT)-guided system to address these needs. We established an orthotopic pancreatic ductal adenocarcinoma (PDAC) mouse model to access BLT. Mice underwent multi-projection and multi-spectral bioluminescence imaging (BLI), followed by CBCT imaging in an animal irradiator for BLT reconstruction and radiation planning. With optimized absorption coefficients, BLT localized PDAC at 1.25 ± 0.19 mm accuracy. To account for BLT localization uncertainties, we expanded the BLT-reconstructed volume with margin to form planning target volume(PTVBLT) for radiation planning, covering 98.7 ± 2.2% of PDAC. The BLT-guided conformal plan can cover 100% of tumors with limited normal tissue involvement across both inter-animal and inter-fraction cases, superior to the 2D BLI-guided conventional plan. BLT offers unique opportunities to localize PDAC for conformal irradiation, minimize normal tissue involvement, and support reproducibility in RT studies.

Efficacy of nonpharmacological interventions for severe radiation-induced oral mucositis among head and neck cancer patients: A network meta-analysis of randomised controlled trials

AIMS AND OBJECTIVES

To assess the effectiveness of different nonpharmacological treatments for severe radiation-induced oral mucositis in patients with head and neck cancer.

BACKGROUND

Radiation-induced oral mucositis is highly prevalent in patients with head and neck cancer. Current medications for radiation-induced oral mucositis are limited in effectiveness and susceptible to side effects, and while there is an increasing adoption of nonpharmacological interventions, the optimal one remains unclear.

DESIGN

Systematic review and network meta-analysis based on the PRISMA-NMA guidelines.

METHODS

Six databases were searched. Two authors independently performed the literature screening, data extraction and methodological quality assessment of the included studies. Traditional pairwise meta-analysis was performed by R Studio. A network meta-analysis was then conducted to assess the effects of nonpharmacological interventions for severe radiation-induced oral mucositis in patients with head and neck cancer.

RESULTS

Fifty-two studies involving seven types of nonpharmacological interventions were enrolled. The network meta-analysis indicated that natural plant-based therapies might be the most effective, health education interventions might be the second most effective, and honey might be the third most effective interventions for reducing the incidence of severe radiation-induced oral mucositis. For reducing the incidence of severe oral mucositis-related pain, the pairwise meta-analysis showed that only natural plant-based therapies and health education interventions were effective.

CONCLUSIONS

Nonpharmacological interventions are effective in the management of severe radiation-induced oral mucositis among patients with head and neck cancer.

RELEVANCE TO CLINICAL PRACTICE

Nonpharmacological interventions are a category of safe and effective adjunctive therapies that should be encouraged in clinical practice.

TRIAL REGISTRATION DETAILS

CRD42023400745.

TGF-β3 increases the severity of radiation-induced oral mucositis and salivary gland fibrosis in a mouse model

PURPOSE

Toxicities from head and neck (H&N) radiotherapy (RT) may affect patient quality of life and can be dose-limiting. Proteins from the transforming growth factor beta (TGF-β) family are key players in the fibrotic response. While TGF-β1 is known to be pro-fibrotic, TGF-β3 has mainly been considered anti-fibrotic. Moreover, TGF-β3 has been shown to act protective against acute toxicities after radio- and chemotherapy. In the present study, we investigated the effect of TGF-β3 treatment during fractionated H&N RT in a mouse model.

MATERIALS AND METHODS

30 C57BL/6J mice were assigned to three treatment groups. The RT + TGF-β3 group received local fractionated H&N RT with 66 Gy over five days, combined with TGF-β3-injections at 24-hour intervals. Animals in the RT reference group received identical RT without TGF-β3 treatment. The non-irradiated control group was sham-irradiated according to the same RT schedule. In the follow-up period, body weight and symptoms of oral mucositis and lip dermatitis were monitored. Saliva was sampled at five time points. The experiment was terminated 105 d after the first RT fraction. Submandibular and sublingual glands were preserved, sectioned, and stained with Masson's trichrome to visualize collagen.

RESULTS

A subset of mice in the RT + TGF-β3 group displayed increased severity of oral mucositis and increased weight loss, resulting in a significant increase in mortality. Collagen content was significantly increased in the submandibular and sublingual glands for the surviving RT + TGF-β3 mice, compared with non-irradiated controls. In the RT reference group, collagen content was significantly increased in the submandibular gland only. Both RT groups displayed lower saliva production after treatment compared to controls. TGF-β3 treatment did not impact saliva production.

CONCLUSIONS

When repeatedly administered during fractionated RT at the current dose, TGF-β3 treatment increased acute H&N radiation toxicities and increased mortality. Furthermore, TGF-β3 treatment may increase the severity of radiation-induced salivary gland fibrosis.

Acute normal tissue responses in a murine model following fractionated irradiation of the head and neck with protons or X-rays

BACKGROUND

The purpose of this study was to investigate acute normal tissue responses in the head and neck region following proton- or X-irradiation of a murine model.

MATERIALS AND METHODS

Female C57BL/6J mice were irradiated with protons (25 or 60 MeV) or X-rays (100 kV). The radiation field covered the oral cavity and the major salivary glands. For protons, two different treatment plans were used, either with the Bragg Peak in the middle of the mouse (BP) or outside the mouse (transmission mode; TM). Delivered physical doses were 41, 45, and 65 Gy given in 6, 7, and 10 fractions for BP, TM, and X-rays, respectively. Alanine dosimetry was used to assess delivered doses. Oral mucositis and dermatitis were scored using CTC v.2.0-based tables. Saliva was collected at baseline, right after end of irradiation, and at day 35.

RESULTS

The measured dose distribution for protons (TM) and X-rays was very similar. Oral mucositis appeared earlier, had a higher score and was found in a higher percentage of mice after proton irradiation compared to X-irradiation. Dermatitis, on the other hand, had a similar appearance after protons and X-rays. Compared to controls, saliva production was lower right after termination of proton- and X-irradiation. The BP group demonstrated saliva recovery compared to the TM and X-ray group at day 35.

CONCLUSION

With lower delivered doses, proton irradiation resulted in similar skin reactions and increased oral mucositis compared to X-irradiation. This indicates that the relative biological effectiveness of protons for acute tissue responses in the mouse head and neck is greater than the clinical standard of 1.1. Thus, there is a need for further investigations of the biological effect of protons in normal tissues.

Cytokine Levels in Saliva Are Associated with Salivary Gland Fibrosis and Hyposalivation in Mice after Fractionated Radiotherapy of the Head and Neck

Cytokines are mediators of inflammation that could lead to fibrosis. The aim was to monitor cytokine levels in saliva and serum after locally fractionated radiotherapy of the head and neck in mice and investigate associations with salivary gland fibrosis and hyposalivation. C57BL/6 mice were randomized to sham or X-ray irradiation of 66 Gy in 10 fractions over 5 days. Blood and saliva were collected on days -7, 5, 35, 80, and 105 following cytokine analysis. The harvested submandibular salivary gland was assessed for the presence of fibrosis. Decision tree regression analysis was used to investigate whether cytokine levels could predict late endpoints in terms of hyposalivation or fibrosis. Significant formation of fibrosis in gland tissue and reduced saliva production was found after irradiation. The pro-inflammatory cytokines IL-1α, TNF, TIMP1, G-CSF, KC, and MIP-1α showed increased levels in saliva in irradiated mice and a strong correlation with late endpoints. The decision tree analysis largely separated controls from irradiated animals, with IL-1α being the strongest predictor. Pro-inflammatory cytokines in saliva, but not in serum, were associated with late endpoints. This indicates that cytokine expression in saliva is a good biomarker for local salivary gland damage with IL-1α as the strongest single predictor.