Combining physical and biologic parameters to predict radiation-induced lung toxicity in patients with non-small-cell lung cancer treated with definitive radiation therapy

USP11 Exacerbates Radiation-Induced Pneumonitis by Activating Endothelial Cell Inflammatory Response via OTUD5-STING Signaling

PURPOSE

Radiation-induced pneumonitis (RIP) seriously limits the application of radiation therapy in the treatment of thoracic tumors, and its etiology and pathogenesis remain elusive. This study aimed to elucidate the role of ubiquitin-specific peptidase 11 (USP11) in the progression of RIP and the associated underlying mechanisms.

METHODS AND MATERIALS

Changes in cytokines and infiltrated immune cells were detected by enzyme-linked immunosorbent assays and immunohistochemistry after exposure to 20 Gy x-ray with whole-thorax irradiation. The effects of USP11 expression on endothelial cell proliferation and apoptosis were analyzed by costaining of CD31/Ki67 and CD31/caspase-3 in vivo, and the production of cytokines and reactive oxygen species was confirmed by reverse-transcription polymerase chain reaction and flow cytometry in vitro. Comprehensive proteome and ubiquitinome analyses were used for USP11 substrate screening after radiation. Results were verified by Western blotting and coimmunoprecipitation experiments. Recombinant adeno-associated virus lung vectors expressing OTUD5 were used for localized overexpression of OTUD5 in mouse pulmonary tissue, and immunohistochemistry was conducted to analyze cytokine expression.

RESULTS

The progression of RIP was significantly alleviated by reduced expression of proinflammatory cytokines in both Usp11-knockout (Usp11-/-) mice and in mice treated with the USP11 inhibitor mitoxantrone. Likewise, the absence of USP11 resulted in decreased permeability of pulmonary vessels and neutrophils and macrophage infiltration. The proliferation rates of endothelial cells were prominently increased in the Usp11-/- lung, whereas apoptosis in Usp11-/- lungs decreased after irradiation compared with that observed in Usp11+/+ lungs. Conversely, USP11 overexpression increased proinflammatory cytokine expression and reactive oxygen species production in endothelial cells after radiation. Comprehensive proteome and ubiquitinome analyses indicated that USP11 overexpression upregulates the expression of several deubiquitinating enzymes, including USP22, USP33, and OTUD5. We demonstrate that USP11 deubiquitinates OTUD5 and implicates the OTUD5-STING signaling pathway in the progression of the inflammatory response in endothelial cells.

CONCLUSIONS

USP11 exacerbates RIP by triggering an inflammatory response in endothelial cells both in vitro and in vivo, and the OTUD5-STING pathway is involved in the USP11-dependent promotion of RIP. This study provides experimental support for the development of precision intervention strategies targeting USP11 to mitigate RIP.

Synergizing the interaction of single nucleotide polymorphisms with dosiomics features to build a dual-omics model for the prediction of radiation pneumonitis

OBJECTIVE

Radiation pneumonitis (RP) is the major dose-limiting toxicity of thoracic radiotherapy. This study aimed to developed a dual-omics (single nucleotide polymorphisms, SNP and dosiomics) prediction model for symptomatic RP.

MATERIALS AND METHODS

The potential SNPs, which are of significant difference between the RP grade ≥ 3 group and the RP grade ≤ 1 group, were selected from the whole exome sequencing SNPs using the Fisher's exact test. Patients with lung cancer who received thoracic radiotherapy at our institution from 2009 to 2016 were enrolled for SNP selection and model construction. The factorization machine (FM) method was used to model the SNP epistasis effect, and to construct the RP prediction model (SNP-FM). The dosiomics features were extracted, and further selected using the minimum redundancy maximum relevance (mRMR) method. The selected dosiomics features were added to the SNP-FM model to construct the dual-omics model.

RESULTS

For SNP screening, peripheral blood samples of 28 patients with RP grade ≥ 3 and the matched 28 patients with RP grade ≤ 1 were sequenced. 81 SNPs were of significant difference (P < 0.015) and considered as potential SNPs. In addition, 21 radiation toxicity related SNPs were also included. For model construction, 400 eligible patients (including 108 RP grade ≥ 2) were enrolled. Single SNP showed no strong correlation with RP. On the other hand, the SNP-SNP interaction (epistasis effect) of 19 SNPs were modeled by the FM method, and achieved an area under the curve (AUC) of 0.76 in the testing group. In addition, 4 dosiomics features were selected and added to the model, and increased the AUC to 0.81.

CONCLUSIONS

A novel dual-omics model by synergizing the SNP epistasis effect with dosiomics features was developed. The enhanced the RP prediction suggested its promising clinical utility in identifying the patients with severe RP during thoracic radiotherapy.

DNA Repair Genetics and the Risk of Radiation Pneumonitis in Patients With Lung Cancer: A Systematic Review and Meta-analysis

AIMS

ERCC1 rs11615 and ERCC2 rs238406 single nuclear polymorphism (SNPs) are known for their association with treatment outcome, likely related to radiosensitivity of both tumor and normal tissue in patients with non-small-cell lung cancer. This study aimed to review the effect of 1) these ERCC1/2 SNPs and 2) other SNPs of DNA repair genes on radiation pneumonitis (RP) in patients with lung cancer.

MATERIALS AND METHODS

SNPs of our interest included ERCC1 rs11615 and ERCC2 rs238406 and other genes of DNA repair pathways that are functional and biologically active. DNA repair SNPs reported by at least two independent studies were pooled for meta-analysis. The study endpoint was radiation pneumonitis (RP) after radiotherapy. Recessive, dominant, homozygous, heterozygous, and allelic genotype models were used where appropriate.

RESULTS

A total of 16 studies (3080 patients) were identified from the systematic review and 12 studies (2090 patients) on 11 SNPs were included in the meta-analysis. The SNPs were ATM rs189037, ATM rs373759, NEIL1 rs4462560, NEIL1 rs7402844, APE1 rs1130409, XRCC3 rs861539, ERCC1 rs11615, ERCC1 rs3212986, ERCC2 rs238406, ERCC2 rs13181, and XRCC1 rs25487. ERCC1 rs11615 (236 patients) and ERCC2 rs238406 (254 patients) were not significantly associated with RP. Using the allelic model, the G allele for NEIL1 gene was significantly associated with a reduced odds of developing symptomatic (grade ≥2) RP compared to the C allele for rs7402844 (OR 0.70, 95% CI: 0.49, 0.99, P = 0.04). Similarly, the T allele for APE1 gene was significantly associated with a reduced odds of developing symptomatic (grade ≥2) RP compared to the G allele for rs1130409 (OR 0.59, 95% CI: 0.43, 0.81, P = 0.001).

CONCLUSION

Genetic variation in the DNA repair pathway genes may play a significant role in the risk of developing radiation pneumonitis in patients with lung cancer. Further studies are needed on genotypic features of DNA repair pathway genes and their association with treatment sensitivity, as such knowledge may guide personalized radiation dose prescription.

Comparison of post-chemoradiotherapy pneumonitis between Asian and non-Asian patients with locally advanced non-small cell lung cancer: a systematic review and meta-analysis

Background

Pneumonitis is a common complication for patients with locally advanced non-small cell lung cancer undergoing definitive chemoradiotherapy (CRT). It remains unclear whether there is ethnic difference in the incidence of post-CRT pneumonitis.

Methods

PubMed, Embase, Cochrane Library, and Web of Science were searched for eligible studies from January 1, 2000 to April 30, 2023. The outcomes of interest were incidence rates of pneumonitis. The random-effect model was used for statistical analysis. This meta-analysis was registered with PROSPERO (CRD42023416490).

Findings

A total of 248 studies involving 28,267 patients were included. Among studies of CRT without immunotherapy, the pooled rates of pneumonitis for Asian patients were significantly higher than that for non-Asian patients (all grade: 66.8%, 95% CI: 59.2%-73.9% vs. 28.1%, 95% CI: 20.4%-36.4%; P < 0.0001; grade ≥2: 25.1%, 95% CI: 22.9%-27.3% vs. 14.9%, 95% CI: 12.0%-18.0%; P < 0.0001; grade ≥3: 6.5%, 95% CI: 5.6%-7.3% vs. 4.6%, 95% CI: 3.4%-5.9%; P = 0.015; grade 5: 0.6%, 95% CI: 0.3%-0.9% vs. 0.1%, 95% CI: 0.0%-0.2%; P < 0.0001). Regarding studies of CRT plus immunotherapy, Asian patients had higher rates of all-grade (74.8%, 95% CI: 63.7%-84.5% vs. 34.3%, 95% CI: 28.7%-40.2%; P < 0.0001) and grade ≥2 (34.0%, 95% CI: 30.7%-37.3% vs. 24.6%, 95% CI: 19.9%-29.3%; P = 0.001) pneumonitis than non-Asian patients, but with no significant differences in the rates of grade ≥3 and grade 5 pneumonitis. Results from subgroup analyses were generally similar to that from the all studies. In addition, the pooled median/mean of lung volume receiving ≥20 Gy and mean lung dose were relatively low in Asian studies compared to that in non-Asian studies.

Interpretation

Asian patients are likely to have a higher incidence of pneumonitis than non-Asian patients, which appears to be due to the poor tolerance of lung to radiation. Nevertheless, these findings are based on observational studies and with significant heterogeneity, and need to be validated in future large prospective studies focusing on the subject.

Funding

None.

Effect of PD-1 Inhibitor Combined with X-Ray Irradiation on the Inflammatory Microenvironment and Lung Tissue Injury in Mice

Purpose

This study was designed to evaluate the effects of PD-1 inhibitor on lung tissue morphology and the immune system in a mouse model of radiation-induced lung injury (RILI) and to assess interactions between radiation therapy and PD-1 inhibition.

Methods

Twenty C57BL/6 mice were divided randomly into four groups of five mice each. Mice were treated with an anti-mouse PD-1 monoclonal antibody, whole thorax irradiation, both or neither. Lung tissue morphology and pathological changes were assessed by hematoxylin-eosin staining; lung fibrosis was assessed by Masson staining and analysis of hydroxyproline; CD3+, CD4+, and CD8+ T lymphocytes in lung tissues were detected immunohistochemically; and the concentrations of transforming growth factor-β1 (TGF-β1) and interleukin-6 (IL-6) in lung tissue were evaluated by cytokine multiplex analysis.

Results

Lung injury scores and indicators of pulmonary fibrosis were higher in mice administration whole thorax irradiation than in control mice. Inflammatory infiltrate scores, alveoli deformation scores, collagen volume fractions and hydroxyproline contents in lung tissues were all significantly higher in mice administered PD-1 inhibitor plus irradiation than in the other three groups. Similarly, the percentages of CD3+ and CD8+T cells and the concentrations of IL-6 and TGF-β1 in lung tissue were significantly higher in mice treated with radiation and PD-1 inhibitor than in the other groups. However, PD-1 inhibitor and irradiation interacted significantly only in the elevation of TGF-β1 level.

Conclusion

Whole thorax X-ray irradiation in mice can cause pulmonary injury and fibrosis, which could be exacerbated by PD-1 inhibitors. Radiotherapy combined with PD-1 inhibitors may aggravate RILI by synergistically upregulating TGF-β1 expression, thereby affecting the immune-inflammatory microenvironment in the lungs.

Changes in Blood Biomarkers of Angiogenesis and Immune Modulation after Radiation Therapy and Their Association with Outcomes in Thoracic Malignancies

The effects of radiotherapy on systemic immunity remain to be fully characterized in a disease-specific manner. The aim of the study was to examine potential biomarkers of systemic immunomodulation when using radiotherapy for thoracic malignancies. Serial blood samples were collected from 56 patients with thoracic malignancies prior (RTbaseline), during (RTduring) and at the end of radiotherapy (RTend), as well as at the first (FU1) and second follow-up (FU2). The changes in serum levels of IL-10, IFN-γ, IL-12p70, IL-13, IL-1β, IL-4, IL-6, IL-8, TNF-α, bFGF, sFlt-1, PlGF, VEGF, VEGF-C, VEGF-D and HGF were measured by multiplexed array and tested for associations with clinical outcomes. We observed an increase in the levels of IL-10, IFN-γ, PlGF and VEGF-D and a decrease in those of IL-8, VEGF, VEGF-C and sFlt-1 during and at the end of radiotherapy. Furthermore, baseline concentration of TNF-α significantly correlated with OS. IL-6 level at RTend and FU1,2 correlated with OS (RTend: p = 0.039, HR: 1.041, 95% CI: 1.002-1.082, FU1: p = 0.001, HR: 1.139, 95% CI: 1.056-1.228, FU2: p = 0.017, HR: 1.101 95% CI: 1.018-1.192), while IL-8 level correlated with OS at RTduring and RTend (RTduring: p = 0.017, HR: 1.014, 95% CI: 1.002-1.026, RTend: p = 0.004, HR: 1.007, 95% CI: 1.061-1.686). In conclusion, serum levels of TNF-α, IL-6 and IL-8 are potential biomarkers of response to radiotherapy. Given the recent implementation of immunotherapy in lung and esophageal cancer, these putative blood biomarkers should be further validated and evaluated in the combination or sequential therapy setting.

Management of Immune-Related Adverse Events in Patients With Non-Small Cell Lung Cancer

With proven efficacy of the use of immunotherapy in almost all stages of NSCLC, immunotherapy toxicity has become a very important topic that requires immediate recognition and management. The diagnosis of toxicities associated with immunotherapy in lung cancer can be very challenging and often requires multidisciplinary effort. This mini review gives an overview of the diagnosis and management of immune-related adverse events that arise from using immunotherapy in NSCLC, as well as the potential biomarkers for its early identification and future directions.

Phase II Trial of Flaxseed to Prevent Acute Complications After Chemoradiation for Lung Cancer

Background: Thoracic radiotherapy is complicated by acute radiation-induced adverse events such as radiation pneumonitis (RP) and radiation esophagitis (RE). Based on preclinical work and a randomized pilot trial from our laboratory, this single-arm phase II trial investigated administering flaxseed as a radioprotector in patients receiving definitive chemoradiation for nonsmall cell lung cancer (NSCLC). Methods: Between June 2015 and February 2018, 33 patients with locally advanced or metastatic NSCLC with planned definitive chemoradiation were enrolled. Finely-ground Linum usitatissimum L. (Linaceae; flaxseed or linseed) in 40-g packets were provided for daily consumption in any patient-desired formulation 1 week before radiotherapy and throughout radiotherapy as tolerated. The primary outcomes were overall adverse events, with particular focus on Grade ≥3 RP, and flaxseed tolerability. Adverse events were graded according to CTCAE v4.0. Results: Of the 33 patients enrolled, 5 patients (15%) did not receive chemoradiation, 4 (12%) withdrew promptly after enrollment, 4 (12%) did not return a flaxseed consumption log, and 1 patient had irritable bowel syndrome (3%). The remaining 19 patients (57%) had chemoradiation and flaxseed ingestion with a mean completion and standard deviation of the intended flaxseed course of 62% ± 8.3%. Nine (50%) of these 19 patients reported difficulties with flaxseed consumption, citing nausea, constipation, odynophagia, or poor taste or texture. One patient (5%), with unverifiable flaxseed consumption, developed Grade 3 RP. There were no cases of Grade 2 RP. Six patients (32%) developed Grade 2 RE, but no patients developed Grade ≥3 RE. Median overall and progression-free survival were 31 and 12 months, respectively. Conclusions: Despite the low incidence of acute radiation-induced complications reported, significant treatment-related gastrointestinal toxicities and subsequently low flaxseed tolerability inhibit accurate determination of flaxseed effect in patients receiving concurrent thoracic chemoradiation. Thus, further investigations should focus on optimizing flaxseed formulation for improved tolerability and evaluation. CTR #: NCT02475330, https://clinicaltrials.gov/ct2/show/study/NCT02475330.

Risk factor of pneumonitis on dose-volume relationship for chemoradiotherapy with durvalumab: Multi-institutional research in Japan

Objectives

To estimate appropriate dose-volume parameters for avoidance of pneumonitis in use of chemoradiotherapy and durvalumab for treatment of lung cancer.

Materials and methods

Patients with non-small cell lung cancer treated with concurrent chemoradiotherapy followed by durvalumab at 9 centers were enrolled in the study. Three-dimensional radiotherapy, intensity modulated radiotherapy, and proton beam therapy were used. The frequency and severity of pneumonitis and the dose-volume relationship for normal lung were evaluated. Univariable and multivariable analyses were conducted to identify risk factors. A covariate adjusted hazard ratio was then estimated for the percentages of normal lung volume irradiated at ≥ X Gy (Vx) (X = 5-40) and lung volume non-irradiated at ≥ X Gy (X = 5-40), with the covariates selected in the variable selection. Cumulative incidence functions and covariate adjusted hazard ratios were also estimated for dichotomized variables, with estimated cut-off points.

Results

A total of 91 patients were enrolled in the study. The median time from the start of radiotherapy to development of pneumonitis was 4.1 months. Pneumonitis was observed in 80 patients (88%), including grade 2 or severe pneumonitis in 31 (34%) and ≥ grade 3 pneumonitis in 11 (12%). Pneumonitis was inside the irradiation field in 73 of the 80 patients (91%). The selected factors for ≥ grade 2 pneumonitis were V₂₀, and primary site (upper lobe) in multivariable analysis. The cut off value of V₂₀ was 18.99%, and there was a significant difference between V₂₀ of < 18.77 and ≥ 18.77.

Conclusion

Though there are some limitation of this study, the basic concept of concurrent chemoradiotherapy with an emphasis on V₂₀ remains unchanged in use of durvalumab. However, we recommend reduction of V₂₀ to as small a value as possible in use of this therapy.

Cytokine Profiles of Non-Small Cell Lung Cancer Patients Treated with Concurrent Chemoradiotherapy with Regards to Radiation Pneumonitis Severity

The immunologic aspects of radiation pneumonitis (RP) are unclear. We analyzed variations in cytokine profiles between patients with grade (Gr) 0–1 and Gr ≥ 2 RP. Fifteen patients undergoing concurrent chemoradiotherapy for non-small cell lung cancer were included. Blood samples of 9 patients with Gr 0–1 and 6 with Gr ≥ 2 RP were obtained from the Biobank. Cytokine levels were evaluated using an enzyme linked immunosorbent assay at before radiotherapy (RT) initiation, 1, 3, and 6 weeks post-RT initiation, and 1 month post-RT completion. Concentrations of granulocyte colony-stimulating factor (G-CSF), interleukin (IL)-6, IL-10, IL-13, IL-17, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, and transforming growth factor (TGF)-β were analyzed; none were related to the occurrence of Gr ≥ 2 RP at pre-RT initiation. At 3 weeks, relative changes in the G-CSF, IL-6, and IFN-γ levels differed significantly between the groups (p = 0.026, 0.05 and 0.026, respectively). One month post-RT completion, relative changes of IL-17 showed significant differences (p = 0.045); however, relative changes in TNF-α, IL-10, IL-13, and TGF-β, did not differ significantly. Evaluation of changes in IL-6, G-CSF, and IFN-γ at 3 weeks after RT initiation can identify patients pre-disposed to severe RP. The mechanism of variation in cytokine levels in relation to RP severity warrants further investigation.

Identifying Circulating and Lung Tissue Cytokines Associated with Thoracic Irradiation and AEOL 10150 Treatment in a Nonhuman Primate Model

Inflammatory cytokines have been suggested to play important roles in radiation-induced lung injury (RILI). Identifying significantly changed circulating and tissue cytokines after thoracic irradiation will aid in deciphering the mechanism of RILI and identifying potential biomarkers to predict clinical outcome. Herein, the levels of 24 cytokines were measured in serial plasma samples and lung tissue samples collected from a pilot study where nonhuman primates (NHPs) received 11.5 Gy whole thoracic lung irradiation (WTLI) and were then treated with or without a medical countermeasure, AEOL 10150 [a superoxide dismutase (SOD) mimetic]. Seven plasma cytokines (i.e., IP-10, MCP-1, IL-12, IL-15, IL-16, IL-7 and IL-6) were found to be significantly changed at different time points due to WTLI. Plasma IP-10 and MDC were significantly changed between the vehicle group and the drug group. The levels of IP-10, MCP-1, MIP-1α, TARC, IL-17, TNF-β and IL-6 were significantly elevated in the lung tissue lysates of NHPs that received WTLI versus radiation-naïve NHPs. The terminal plasma concentrations of IP-10, MDC, TARC, IL-12, IL-15 and IL-6 were significantly correlated with their levels in the lung tissue. The levels of four cytokines (MCP-4, IL-17, TNF-β and IL-2) at early time points (≤8 weeks postirradiation) were significantly correlated with their terminal plasma levels, respectively. Statistical analysis indicated that circulating cytokines could be discriminatory predictors of AEOL 10150 treatment. Taken together, our data suggested that the cytokine profiles were significantly changed after WTLI as well as mitigator treatment, and that the plasma cytokine profiles could potentially be used to distinguish vehicle or mitigator treatment after WTLI in a NHP model.

Evaluation of cytokine expression and circulating immune cell subsets as potential parameters of acute radiation toxicity in prostate cancer patients

One of the challenges of radiation oncology in the era of personalized medicine is identification of biomarkers associated with individual radiosensitivity. The aim of research was to evaluate the possible clinical value of the associations between clinical, physical, and biological factors, and risk for development of acute radiotoxicity in patients with prostate cancer. The study involved forty four patients treated with three-dimensional conformal radiotherapy. The concentrations of IL-1β, IL-2, IL-6, IFN-γ and TGF-β1 were assessed before radiotherapy, after 5th, 15th and 25th radiotherapy fractions, at the end, and 1 month after the end of radiotherapy. Cytokine gene expression was determined in peripheral blood mononuclear cells. The univariate analysis of circulating cytokine levels during radiotherapy showed that increased serum concentrations of IL-6 were significantly associated with higher grade of acute genitourinary toxicity. The multivariate analysis demonstrated that increased level of IL-6 during the radiotherapy was significantly associated with higher grade of acute genitourinary toxicity across treatment. TGF-β expression levels significantly decreased during course of radiotherapy. Research indicates that changes in circulating cytokine levels might be important parameter of radiotoxicity in patients with prostate cancer. These findings suggest that future studies based on multi-parameter examination are necessary for prediction of individual radiosensitivity.

LncRNA-RP11 Modulates TGF-β1-Activated Radiation-Induced Lung Injury Through Downregulating microRNA-29a

Radiation-induced lung injury (RILI) is one of the most serious complications of thoracic radiation and TGF-β1 is a central regulator of RILI. However, the molecular mechanism underlying the fine tuning of TGF-β1 signaling in RILI has not been fully understood. In the current study, differentially expressed long non-coding RNAs (LncRNAs) among human lung fibroblasts cell lines HFL-1 and WI-38 treated with TGF-β1, were identified by microarray and validated by real time PCR. LncRNA-RP11 was found to be the most increased LncRNA and it mediated the promotion of fibrogenic activity in human lung fibroblasts after TGF-β1 treatment. Bioinformatic analysis revealed that TGF-β1 may be associated with the component and structure of extracellular matrix in lung fibroblasts cells, and LncRNA-RP11 was predicted and confirmed to be a competing endogenous RNA by directly binding to miR-29a. Functional experiments investigating the biological role of LncRNA-RP11/miR-29a axis in RILI, were then carried out in human fibroblasts. The results showed that radiation promoted the expression of LncRNA-RP11, but regressed the expression of miR-29a. Furthermore, radiation elevated the expression of various common collagenic proteins, which could be abolished by overexpression of miR-29a.

Intermediate Dose-Volume Parameters, Not Low-Dose Bath, Is Superior to Predict Radiation Pneumonitis for Lung Cancer Treated With Intensity-Modulated Radiotherapy

Purpose

Although intensity-modulated radiotherapy (IMRT) is now a preferred option for conventionally fractionated RT in lung cancer, the commonly used cutoff values of the dosimetric constraints are still mainly derived from the data using three-dimensional conformal radiotherapy (3D-CRT). We aimed to compare the prediction performance among different dosimetric parameters for acute radiation pneumonitis (RP) in patients with lung cancer received IMRT.

Methods

A total of 236 patients treated with IMRT were retrospectively reviewed in two independent groups of lung cancer from January 2014 to August 2018. The primary endpoint was grade 2 or higher acute RP (RP2). Dose metrics were generated from the bilateral lung volume outside GTV (Vdose_G) and PTV (Vdose_P). The associations of RP2 with clinical variables, dose-volume parameters and mean lung dose (MLD) were analyzed by univariate and multivariate logistic regression. The power of discrimination among each predictor was assessed by employing the bootstrapped area under the receiver operating characteristic curve (AUC), net reclassification improvement (NRI), and the integrated discrimination improvement (IDI).

Results

Thirty-four (14.4%) out of 236 patients developed acute RP2 after the end of IMRT. The clinical parameters were identified as less important predictors for RP2 based on univariate and multivariate analysis. In both studied groups, the significance of association was more convincing in V20_P, V30_P, and MLD_P (smaller Ps) than V5_G and V5_P. The largest bootstrapped AUC was identified for the V30_P. We found a trend of better discriminating performance for the V20_P and V30_P, and MLD_P than the V5_G and V5_P according to the higher values in AUC, IDI, and NRI analysis. To limit RP2 incidence less than 20%, the V30_P cutoff was 14.5%.

Conclusions

This study identified the intermediate dose-volume parameters V20_P and V30_P with better prediction performance for acute RP2 than low-dose metrics V5_G and V5_P. Among all studied predictors, the V30_P had the best discriminating power, and should be considered as a supplement to the traditional dose constraints in lung cancer treated with IMRT.

Radiation Exposure-Induced Changes in the Immune Cells and Immune Factors of Mice With or Without Primary Lung Tumor

Recent studies have demonstrated that radiation activates in situ antitumor immunity and consequently induced a synergistic effect of radiotherapy and immunotherapy. However, studies related to radiation-induced changes in immune system of tumor-bearing mice are limited, which are of great significance to improve the efficacy of radioimmunotherapy. In this study, we first established a primary lung tumor mouse model using urethane. Then part of the right lung of the mouse was exposed to X-ray irradiation with a computed tomography-guided small animal irradiator and the changes of immune cells in both peripheral blood and spleen were determined by flow cytometry. Besides, the levels of both cytokines and immunoglobulins in mouse serum were detected by a protein chip. We found that B lymphocytes increased while CD8⁺ T lymphocytes reduced significantly. Interleukin-3 (IL-3), IL-6, regulated upon activation, normally T-expressed, and presumably secreted factor (RANTES), and vascular endothelial growth factor (VEGF) were found to be decreased after tumor formation, and the similar results have also been observed with kappa, IgG3, IgE, IgM, and IgG2a. After irradiation, lower concentrations of IgD, kappa, and IgM were found in the serum. Our findings indicate that localized tumor irradiation caused some obvious changes like inhibiting the ability of innate immunity, and these changes may be useful in predicting prognosis.

Ultra-high dose rate effect on circulating immune cells: A potential mechanism for FLASH effect?

PURPOSE

"FLASH" radiotherapy (RT) is a potential paradigm-changing RT technology with marked tumor killing and normal tissue sparing. However, the mechanism of the FLASH effect is not well understood. We hypothesize that the ultra-high dose rate FLASH-RT significantly reduces the killing of circulating immune cells which may partially contribute to the reported FLASH effect.

METHODS

This computation study directly models the effect of radiation dose rate on the killing of circulating immune cells. The model considers an irradiated volume that takes up A% of cardiac output and contains B% of total blood. The irradiated blood volume and dose were calculated for various A%, B%, blood circulation time, and irradiation time (which depends on the dose rate). The linear-quadratic model was used to calculate the extent of killing of circulating immune cells at ultra-high vs. conventional dose rates.

RESULTS

A strong sparing effect on circulating blood cells by FLASH-RT was noticed; i.e., killing of circulating immune cells reduced from 90% to 100% at conventional dose rates to 5-10% at ultra-high dose rates. The threshold FLASH dose rate was determined to be ~40 Gy/s for mice in an average situation (A% = 50%), consistent with the reported FLASH dose rate in animal studies, and it was approximately one order of magnitude lower for humans than for mice. The magnitude of this sparing effect increased with the dose/fraction, reached a plateau at 30-50 Gy/fraction, and almost completely vanished at 2 Gy/fraction.

CONCLUSION

We have calculated a strong sparing effect on circulating immune cells by FLASH-RT, which may contribute to the reported FLASH effects in animal studies.

The Possibility of Using Genotoxicity, Oxidative Stress and Inflammation Blood Biomarkers to Predict the Occurrence of Late Cutaneous Side Effects after Radiotherapy

Despite the progresses performed in the field of radiotherapy, toxicity to the healthy tissues remains a major limiting factor. The aim of this work was to highlight blood biomarkers whose variations could predict the occurrence of late cutaneous side effects. Two groups of nine patients treated for Merkel Cell Carcinoma (MCC) were established according to the grade of late skin toxicity after adjuvant irradiation for MCC: grade 0, 1 or 2 and grade 3 or 4 of RTOG (Radiation Therapy Oncology Group)/EORTC (European Organization for Research and Treatment of Cancer). To try to discriminate these 2 groups, biomarkers of interest were measured on the different blood compartments after ex vivo irradiation. In lymphocytes, cell cycle, apoptosis and genotoxicity were studied. Oxidative stress was evaluated by the determination of the erythrocyte antioxidant capacity (superoxide dismutase, catalase, glutathione peroxidase, reduced and oxidized glutathione) as well as degradation products (protein carbonylation, lipid peroxidation). Inflammation was assessed in the plasma by the measurement of 14 cytokines. The most radiosensitive patients presented a decrease in apoptosis, micronucleus frequency, antioxidant enzyme activities, glutathione and carbonyls; and an increase in TNF-a (Tumor Necrosis Factor a), IL-8 (Interleukin 8) and TGF-β1 (Transforming Growth Factor β1) levels. These findings have to be confirmed on a higher number of patients and before radiotherapy and could allow to predict the occurrence of late skin side effects after radiotherapy.

Precise prediction of the radiation pneumonitis in lung cancer: an explorative preliminary mathematical model using genotype information

Purpose: Radiation pneumonitis (RP) is the most significant dose-limiting toxicity and is one major obstacle for lung cancer radiotherapy. Grade ≥2 RP usually needs clinical interventions and serve RP could be life threatening. Clinically, tissue response could be strikingly different even two similar patients after identical radiotherapy. Previous methods for the RP prediction can hardly distinguish substantial variations among individuals. Reliable predictive factors or methods emphasizing the individual differences are strongly desired by clinical radiation oncologists. The purpose of this study is to develop an approach for the personalized RP risk prediction.

Experimental Design: One hundred eighteen lung cancer patients who received radiotherapy were enrolled. Seven hundred thousand single-nucleotide polymorphism (SNP) sites were assessed via Generalized Linear Models via Lasso and Elastic-Net Regularization (GLMNET) to determine their synergistic effects on the RP risk prediction. Non-genetic factors including patient's phenotypes and clinical interventional parameters were separately assessed by statistic test. Based on the results of the aforementioned analysis, a multiple linear regression model named Radiation Pneumonitis Index (RPI) was built, for the assessment of Grade ≥2RP risk.

Results: Only previous surgery and fractional dose were discovered statistical significantly associated with grade ≥2RP. Thirty-nine effective SNPs for predicting the Grade ≥2RP risk were discovered and their coefficients of the synergistic effect were determined. The RPI score can successfully distinguish the RP≥2 population with 92.0% sensitivity and 100% specificity.

Conclusions: Individual radiation sensitivity can be determined with genotype information and personalized radiotherapy could be achieved based on mathematical model result.

X-rays induced IL-8 production in lung cancer cells via p38/MAPK and NF-κB pathway

PURPOSE

It is reported inflammatory cytokine interleukin-8 (IL-8) could predict radiation-induced lung toxicity (RILT). RILT is believed to be a consequence of a cascade of cytokine production. It is considered that vascular endothelial cell and macrophages are the mainly source of cytokines. This study was investigated the production of IL-8 from cancer cells induced by X-rays may involve in the radiation-induced inflammation.

MATERIALS AND METHODS

We analyzed IL-8 in human lung cancer cell lines after expose to X-rays, and we also detect IL-8 in HUVEC cells and THP1 cells as endothelial cell and macrophage model to identify the change in normal cells after expose. Furthermore, we added the inhibitors to the culture with or without radiation to identify the role of MAPK and NF-κB pathways on the radiation-induced secretion of IL-8.

RESULTS

Radiation could induce IL-8 production both in non-lung cancer cells (HUVECs and THP1 cells) and in lung cancer cells (A549 cells, H446 cells, PC-9 cells). Simultaneously, radiation activated p38/MAPK and NF-κB signal pathways in lung cancer cells. Moreover, p38/MAPK inhibitor SB203580 and NF-κB inhibitor BAY11-7082 could block the IL-8 up-regulated by X-rays but JNK inhibitor SP600125, ERK inhibitor U0126, ROS Scavenger NAC could not inhibit this phenomenon.

CONCLUSIONS

X-rays could induce IL-8 production in lung cancer cells, which may be related to the activation of p38/MAPK and NF-κB signaling pathway, providing a new point for elucidating the mechanism of radiation pneumonitis.

External Validation of Radiation-Induced Dyspnea Models on Esophageal Cancer Radiotherapy Patients

Purpose: Radiation-induced lung disease (RILD), defined as dyspnea in this study, is a risk for patients receiving high-dose thoracic irradiation. This study is a TRIPOD (Transparent Reporting of A Multivariable Prediction Model for Individual Prognosis or Diagnosis) Type 4 validation of previously-published dyspnea models via secondary analysis of esophageal cancer SCOPE1 trial data. We quantify the predictive performance of these two models for predicting the maximal dyspnea grade ≥ 2 within 6 months after the end of high-dose chemo-radiotherapy for primary esophageal cancer.

Materials and methods: We tested the performance of two previously published dyspnea risk models using baseline, treatment and follow-up data on 258 esophageal cancer patients in the UK enrolled into the SCOPE1 multi-center trial. The tested models were developed from lung cancer patients treated at MAASTRO Clinic (The Netherlands) from the period 2002 to 2011. The adverse event of interest was dyspnea ≥ Grade 2 (CTCAE v3) within 6 months after the end of radiotherapy. As some variables were missing randomly and cannot be imputed, 212 patients in the SCOPE1 were used for validation of model 1 and 255 patients were used for validation of model 2. The model parameter Forced Expiratory Volume in 1 s (FEV₁), as a predictor to both validated models, was imputed using the WHO performance status. External validation was performed using an automated, decentralized approach, without exchange of individual patient data.

Results: Out of 258 patients with esophageal cancer in SCOPE1 trial data, 38 patients (14.7%) developed radiation-induced dyspnea (≥ Grade 2) within 6 months after chemo-radiotherapy. The discrimination performance of the models in esophageal cancer patients treated with high-dose external beam radiotherapy was moderate, area under curve (AUC) of 0.68 (95% CI 0.55–0.76) and 0.70 (95% CI 0.58–0.77), respectively. The curves and AUCs derived by distributed learning were identical to the results from validation on a local host.

Conclusion: We have externally validated previously published dyspnea models using an esophageal cancer dataset. FEV₁ that is not routinely measured for esophageal cancer was imputed using WHO performance status. Prediction performance was not statistically different from previous training and validation sets. Risk estimates were dominated by WHO score in Model 1 and baseline dyspnea in Model 2. The distributed learning approach gave the same answer as local processing, and could be performed without accessing a validation site's individual patients-level data.

Clinical Management of Risk of Radiation Pneumonia with Serum Markers During the Radiotherapy for Patients with Thoracic Malignant Tumors

Purpose

Risk of radiation pneumonia (RP) could not be effectively detected due to non-specific clinical symptoms in the early stage. The purpose of this investigation was to evaluate serum biomarkers of cytokines interleukin-6 (IL-6), C-reactive protein (CRP) and procalcitonin (PCT) for its early detection in patients with thoracic malignant tumors receiving radiotherapy.

Patients and methods

The clinical data of 105 patients with thoracic malignant tumors (lung cancer, esophageal carcinoma and mediastinal tumors) treated by radiotherapy were retrospectively analyzed. The patients were divided into RP group and non-RP group according to the Common Terminology Criteria for Adverse Events (CTCAE 5.0). The serum level of IL-6 was detected by chemiluminescence, and the level of CRP was measured by nephelometry during radiotherapy. The level of PCT, one of the specific indicators to distinguish infection and non-infectious etiologies, was also detected by chemiluminescence.

Results

Among 105 patients treated by radiotherapy, 28 developed RP, and the other 77 had no RP. There was no significant difference in the risk of RP between patients’ factors (age, sex, PS score, smoking, tumor type) and treatment factors (chemotherapy, V₅, GTV dose). However, chronic obstructive pulmonary disease (COPD), V₂₀ and mean lung dose (MLD) were significantly different between the two groups (χ² = 4.131, 3.986, 7.830, P < 0.05). Furthermore, PCT levels were also found to have insignificant differences between RP group and non-RP group (P > 0.05). However, there were significant differences between the groups in the levels of IL-6 and CRP (P < 0.05). The IL-6 levels significantly increased earlier than that of conventional CT imaging when patients suffering from RP and peaked at 6 weeks during radiotherapy. CRP had a similar change as IL-6. Single cytokine and combination of IL-6 and CRP possessed a good ability to predict RP with the AUC of IL-6 of 0.89±0.04 (95% CI, 0.80–0.95, P<0.001), CRP of 0.87±0.05 (95% CI, 0.78–0.94, P<0.001), IL-6 + CRP of 0.92 ± 0.03 (95% CI, 0.83–0.97, P < 0.001), respectively.

Conclusion

The combined detection of serum IL-6, CRP and PCT may be an effectual method for early detection and clinical practice management of risk of RP.

Cytokines expression levels from tissue, plasma or serum as promising clinical biomarkers in adenocarcinoma of the prostate: a systematic review of recent findings

Prostate cancer (PC) is a common cancer (excluding non-melanoma skin cancer) in men in many parts of the world, although incidence and mortality rates vary significantly by population. In current medical practice, prognostic markers for PC include the presenting serum prostate-specific antigen (PSA) level, tumour Gleason score (GS) and clinical tumour stage. However, existing pre-treatment factors cannot be used to predict acute radiotherapy (RT)-induced toxicity. Therefore, new protein biomarkers are required in RT oncology to improve decision-making, treatment and therapy monitoring for PC patients. The aim of this systematic review is to the update potential research to address the difference in cytokine expression and their association with RT-induced toxicity and clinical outcomes. Studies were collected after searching three electronic databases: PubMed, Medline, and Google Scholar. An additional search was carried out through cross-check on a bibliography of selected articles. After the selection process made by two of the authors, 19 articles met the inclusion criteria and were included in the systematic review. Results from previous studies identified elevated levels of cytokines have been reported in several types of cancers and have sometimes correlated with disease progression or prognosis. Elevated levels of cytokine were noticed after immediate exposure to RT and their association with RT-induced acute/late toxicity of PC patients. Moreover, above studies also identified overexpression of cytokines on tumour biopsies and correlation with shortening cancer-specific survival and biochemical recurrence. Thus, altered levels of cytokine might be predictive biomarkers for RT-induced and clinical outcomes of PC patients.

Machine Learning to Build and Validate a Model for Radiation Pneumonitis Prediction in Patients with Non-Small Cell Lung Cancer

PURPOSE

Radiation pneumonitis is an important adverse event in patients with non-small cell lung cancer (NSCLC) receiving thoracic radiotherapy. However, the risk of radiation pneumonitis grade ≥ 2 (RP2) has not been well predicted. This study hypothesized that inflammatory cytokines or the dynamic changes during radiotherapy can improve predictive accuracy for RP2.

EXPERIMENTAL DESIGN

Levels of 30 inflammatory cytokines and clinical information in patients with stages I-III NSCLC treated with radiotherapy were from our prospective studies. Statistical analysis was used to select predictive cytokine candidates and clinical covariates for adjustment. Machine learning algorithm was used to develop the generalized linear model for predicting risk RP2.

RESULTS

A total of 131 patients were eligible and 17 (13.0%) developed RP2. IL8 and CCL2 had significantly (Bonferroni) lower expression levels in patients with RP2 than without RP2. But none of the changes in cytokine levels during radiotherapy was significantly associated with RP2. The final predictive GLM model for RP2 was established, including IL8 and CCL2 at baseline level and two clinical variables. Nomogram was constructed based on the GLM model. The model's predicting ability was validated in the completely independent test set (AUC = 0.863, accuracy = 80.0%, sensitivity = 100%, specificity = 76.5%).

CONCLUSIONS

By machine learning, this study has developed and validated a comprehensive model integrating inflammatory cytokines with clinical variables to predict RP2 before radiotherapy that provides an opportunity to guide clinicians.

Diagnosis and management of pulmonary toxicity associated with cancer immunotherapy

Pulmonary toxicity of cancer immunotherapies has emerged as an important clinical event that requires prompt identification and management. Although often referred to as pneumonitis, pulmonary toxicity associated with immunotherapy covers a broad and overlapping spectrum of pulmonary manifestations, and, once suspected, the range of differential diagnoses of infectious and neoplastic processes might make the diagnostic process challenging for physicians. Optimal care can require multidisciplinary effort by pulmonologists, medical oncologists, and radiologists, and awareness of the possibility of treatment-induced pulmonary toxicity by emergency department and primary care physicians. This Viewpoint gives an overview of the diagnosis and management of pulmonary toxicity arising from cancer immunotherapy, including widely used treatments, such as immune checkpoint inhibitors, and emerging therapies, such as chimeric antigen receptor T cells.

Radiation pneumonitis in lung cancer treated with volumetric modulated arc therapy

Background

Few studies to date have assessed the incidence of radiation pneumonitis (RP) in lung cancer patients who have been treated with volumetric modulated arc therapy (VMAT). This study is aimed at reporting the RP incidence rate and the risk factors associated with a symptomatic RP in patients with lung cancer treated with VMAT.

Methods

A total of 77 consecutive lung cancer patients treated with VMAT from 2013 through 2015 were reviewed. RP severity was graded according to the Common Terminology Criteria for Adverse Events (CTCEA) v.4. Univariate and multivariate analyses were performed to identify the significant factors associated with RP.

Results

VMAT allowed us to achieve most planning objectives on the target volumes and organs at risk, for PTV V_95% =96.8%±3.1%, for lung V₅ =41.3%±8.7%, V₁₀ =30.0%±7.1%, V₂₀ =20.9%±5.7%, for heart V₅ =43.2%±29.9%, for esophagus V₆₀ =8.1%±12.9%. The maximum dose of spinal cord was 34.4±9.5 Gy. The overall incidence of symptomatic RP (grade ≥2 by CTCAE) was 28.6% in the entire cohort, and the rate of grade ≥3 RP was 11.7%. Based on the multivariate analysis, factors predictive of symptomatic RP included lung volume receiving ≥10 Gy (V₁₀) (P=0.019) and C-reactive protein changing level (P=0.013).

Conclusions

Our data showed that the incidence rate of RP was acceptable in lung cancer patients treated with VMAT. Additionally, we found that V₁₀ might be an important factor for predicting the development of RP when VMAT was used; but this observation needs to be validated in future studies.

Cytokines and radiation-induced pulmonary injuries

Radiation therapy is one of the most common treatment strategies for thorax malignancies. One of the considerable limitations of this therapy is its toxicity to normal tissue. The lung is the major dose-limiting organ for radiotherapy. That is because ionizing radiation produces reactive oxygen species that induce lesions, and not only is tumor tissue damaged, but overwhelming inflammatory lung damage can occur in the alveolar epithelium and capillary endothelium. This damage may result in radiation-induced pneumonitis and/or fibrosis. While describing the lung response to irradiation generally, the main focus of this review is on cytokines and their roles and functions within the individual stages. We discuss the relationship between radiation and cytokines and their direct and indirect effects on the formation and development of radiation injuries. Although this topic has been intensively studied and discussed for years, we still do not completely understand the roles of cytokines. Experimental data on cytokine involvement are fragmented across a large number of experimental studies; hence, the need for this review of the current knowledge. Cytokines are considered not only as molecular factors involved in the signaling network in pathological processes, but also for their diagnostic potential. A concentrated effort has been made to identify the significant immune system proteins showing positive correlation between serum levels and tissue damages. Elucidating the correlations between the extent and nature of radiation-induced pulmonary injuries and the levels of one or more key cytokines that initiate and control those damages may improve the efficacy of radiotherapy in cancer treatment and ultimately the well-being of patients.

A model combining age, equivalent uniform dose and IL-8 may predict radiation esophagitis in patients with non-small cell lung cancer

BACKGROUND AND PURPOSE

To study whether cytokine markers may improve predictive accuracy of radiation esophagitis (RE) in non-small cell lung cancer (NSCLC) patients.

MATERIALS AND METHODS

A total of 129 patients with stage I-III NSCLC treated with radiotherapy (RT) from prospective studies were included. Thirty inflammatory cytokines were measured in platelet-poor plasma samples. Logistic regression was performed to evaluate the risk factors of RE. Stepwise Akaike information criterion (AIC) and likelihood ratio test were used to assess model predictions.

RESULTS

Forty-nine of 129 patients (38.0%) developed grade ≥2 RE. Univariate analysis showed that age, stage, concurrent chemotherapy, and eight dosimetric parameters were significantly associated with grade ≥2 RE (p < 0.05). IL-4, IL-5, IL-8, IL-13, IL-15, IL-1α, TGFα and eotaxin were also associated with grade ≥2 RE (p < 0.1). Age, esophagus generalized equivalent uniform dose (EUD), and baseline IL-8 were independently associated grade ≥2 RE. The combination of these three factors had significantly higher predictive power than any single factor alone. Addition of IL-8 to toxicity model significantly improves RE predictive accuracy (p = 0.019).

CONCLUSIONS

Combining baseline level of IL-8, age and esophagus EUD may predict RE more accurately. Refinement of this model with larger sample sizes and validation from multicenter database are warranted.

Nebulisation of synthetic lamellar lipids mitigates radiation-induced lung injury in a large animal model

Methods to protect against radiation-induced lung injury (RILI) will facilitate the development of more effective radio-therapeutic protocols for lung cancer and may provide the means to protect the wider population in the event of a deliberate or accidental nuclear or radiological event. We hypothesised that supplementing lipid membranes through nebulization of synthetic lamellar lipids would mitigate RILI. Following pre-treatment with either nebulised lamellar lipids or saline, anaesthetised sheep were prescribed fractionated radiotherapy (30 Gray (Gy) total dose in five 6 Gy fractions at 3–4 days intervals) to a defined unilateral lung volume. Gross pathology in radio-exposed lung 37 days after the first radiation treatment was consistent between treatment groups and consisted of deep red congestion evident on the pleural surface and firmness on palpation. Consistent histopathological features in radio-exposed lung were subpleural, periarteriolar and peribronchial intra-alveolar oedema, alveolar fibrosis, interstitial pneumonia and type II pneumocyte hyperplasia. The synthetic lamellar lipids abrogated radiation-induced alveolar fibrosis and reduced alpha-smooth muscle actin (ASMA) expression in radio-exposed lung compared to saline treated sheep. Administration of synthetic lamellar lipids was also associated with an increased number of cells expressing dendritic cell-lysosomal associated membrane protein throughout the lung.

Exhaled Nitric Oxide Is Useful in Symptomatic Radioactive Pneumonia: A Retrospective Study

The aim was to defect the exhaled nitric oxide (eNO) prediction value of symptomatic radioactive pneumonia (SRP). 64 cases of lung cancer or esophagus cancer, who had the primary radiotherapy (intensity-modulated radiation therapy), were included from 2015 June to 2016 January. During the following, the patients were divided: the symptomatic radiation pneumonia group (SRP, with the CTCAE v4.0 score > 2) and the asymptomatic radiation pneumonia group (ASRP, with CTCAE v4.0 score ≤ 1). All the patients were measured eNO before and at the end of thoracic radiotherapy and gain the posttherapy eNO value and the eNO ratio (posttherapy eNO value/pretherapy eNO value), then the predictive values of eNO toward SRP were measured using the receiver-operating characteristic (ROC). 17 cases were included in the SRP group and the other 47 were included in the ASRP group. The posttherapy eNO was 29.35 (19~60) bbp versus 20.646 (11~37) (P < 0.001), and the ratio was 1.669 (0.61~3.5) versus 0.920 (0.35~1.5) (P < 0.01) (symptomatic versus asymptomatic). ROC showed that the cutoff value of SRP was 19.5 bbp (posttherapy eNO, area under concentration-time curve (AUC) = 0.879) and 1.305 (eNO ratio, AUC = 0.774), which meant that posttherapy eNO and eNO ratio were useful in finding SRP.

A multiobjective Bayesian networks approach for joint prediction of tumor local control and radiation pneumonitis in nonsmall-cell lung cancer (NSCLC) for response-adapted radiotherapy

PURPOSE

Individualization of therapeutic outcomes in NSCLC radiotherapy is likely to be compromised by the lack of proper balance of biophysical factors affecting both tumor local control (LC) and side effects such as radiation pneumonitis (RP), which are likely to be intertwined. Here, we compare the performance of separate and joint outcomes predictions for response-adapted personalized treatment planning.

METHODS

A total of 118 NSCLC patients treated on prospective protocols with 32 cases of local progression and 20 cases of RP grade 2 or higher (RP2) were studied. Sixty-eight patients with 297 features before and during radiotherapy were used for discovery and 50 patients were reserved for independent testing. A multiobjective Bayesian network (MO-BN) approach was developed to identify important features for joint LC/RP2 prediction using extended Markov blankets as inputs to develop a BN predictive structure. Cross-validation (CV) was used to guide the MO-BN structure learning. Area under the free-response receiver operating characteristic (AU-FROC) curve was used to evaluate joint prediction performance.

RESULTS

Important features including single nucleotide polymorphisms (SNPs), micro RNAs, pretreatment cytokines, pretreatment PET radiomics together with lung and tumor gEUDs were selected and their biophysical inter-relationships with radiation outcomes (LC and RP2) were identified in a pretreatment MO-BN. The joint LC/RP2 prediction yielded an AU-FROC of 0.80 (95% CI: 0.70-0.86) upon internal CV. This improved to 0.85 (0.75-0.91) with additional two SNPs, changes in one cytokine and two radiomics PET image features through the course of radiotherapy in a during-treatment MO-BN. This MO-BN model outperformed combined single-objective Bayesian networks (SO-BNs) during-treatment [0.78 (0.67-0.84)]. AU-FROC values in the evaluation of the MO-BN and individual SO-BNs on the testing dataset were 0.77 and 0.68 for pretreatment, and 0.79 and 0.71 for during-treatment, respectively.

CONCLUSIONS

MO-BNs can reveal possible biophysical cross-talks between competing radiotherapy clinical endpoints. The prediction is improved by providing additional during-treatment information. The developed MO-BNs can be an important component of decision support systems for personalized response-adapted radiotherapy.

FoxM1-dependent RAD51 and BRCA2 signaling protects idiopathic pulmonary fibrosis fibroblasts from radiation-induced cell death

Radiation therapy is critical for the control of many tumors and lung is an important dose-limiting organ that impacts radiation dose prescribed to avoid irreversible pulmonary fibrosis in cancer survivors. Idiopathic pulmonary fibrosis (IPF) is a chronic, irreversible lung disease caused by aberrantly activated lung (myo)fibroblasts. The presence of pro-fibrotic, apoptosis-resistant fibroblasts in IPF promotes progressive fibrosis and may have a role in other diseases, if these resistant cells are selected for as a consequence of treatment. However, the pathological response of IPF fibroblasts to radiation compared to non-IPF lung fibroblasts is not known. To address this, we examined fibroblast viability following radiation in lung fibroblasts from IPF and non-IPF patients and the underlying mechanism that protects IPF fibroblasts from radiation-induced death. IPF fibroblasts are significantly more resistant to apoptosis compared to non-IPF lung fibroblasts, suggesting that resistance to radiation-induced cell death is a predominant mechanism leading to lung fibrosis. Analysis of γH2AX induction demonstrated that radiation-induced DNA damage is reduced in IPF fibroblasts and correlates to the activation of the transcription factor forkhead box M1 (FoxM1) and subsequent upregulation of DNA repair proteins RAD51 and BRCA2. FoxM1 activation occurs secondary to FoxO3a suppression in IPF fibroblasts while restoration of FoxO3a function sensitizes IPF fibroblasts to radiation-induced cell death and downregulates FoxM1, RAD51, and BRCA2. Our findings support that increased FoxO3a/FoxM1-dependent DNA repair may be integral to the preservation of death-resistant fibrotic fibroblasts after radiation and that selective targeting of radioresistant fibroblasts may mitigate fibrosis.

Development of a Fully Cross-Validated Bayesian Network Approach for Local Control Prediction in Lung Cancer

The purpose of this study is to demonstrate that a Bayesian network (BN) approach can explore hierarchical biophysical relationships that influence tumor response and predict tumor local control (LC) in non-small-cell lung cancer (NSCLC) patients before and during radiotherapy from a large-scale dataset. Our BN building approach has two steps. First, relevant biophysical predictors influencing LC before and during the treatment are selected through an extended Markov blanket (eMB) method. From this eMB process, the most robust BN structure for LC prediction was found via a wrapper-based approach. Sixty-eight patients with complete feature information were used to identify a full BN model for LC prediction before and during the treatment. Fifty more recent patients with some missing information were reserved for independent testing of the developed pre- and during-therapy BNs. A nested cross-validation (N-CV) was developed to evaluate the performance of the two-step BN approach. An ensemble BN model is generated from the N-CV sampling process to assess its similarity with the corresponding full BN model, and thus evaluate the sensitivity of our BN approach. Our results show that the proposed BN development approach is a stable and robust approach to identify hierarchical relationships among biophysical features for LC prediction. Furthermore, BN predictions can be improved by incorporating during treatment information.

The Role of the Mammalian Target of Rapamycin (mTOR) in Pulmonary Fibrosis

The phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR)-dependent pathway is one of the most integral pathways linked to cell metabolism, proliferation, differentiation, and survival. This pathway is dysregulated in a variety of diseases, including neoplasia, immune-mediated diseases, and fibroproliferative diseases such as pulmonary fibrosis. The mTOR kinase is frequently referred to as the master regulator of this pathway. Alterations in mTOR signaling are closely associated with dysregulation of autophagy, inflammation, and cell growth and survival, leading to the development of lung fibrosis. Inhibitors of mTOR have been widely studied in cancer therapy, as they may sensitize cancer cells to radiation therapy. Studies also suggest that mTOR inhibitors are promising modulators of fibroproliferative diseases such as idiopathic pulmonary fibrosis (IPF) and radiation-induced pulmonary fibrosis (RIPF). Therefore, mTOR represents an attractive and unique therapeutic target in pulmonary fibrosis. In this review, we discuss the pathological role of mTOR kinase in pulmonary fibrosis and examine how mTOR inhibitors may mitigate fibrotic progression.

Prediction of Radiation Esophagitis in Non-Small Cell Lung Cancer Using Clinical Factors, Dosimetric Parameters, and Pretreatment Cytokine Levels

Radiation esophagitis (RE) is a common adverse event associated with radiotherapy for non-small cell lung cancer (NSCLC). While plasma cytokine levels have been correlated with other forms of radiation-induced toxicity, their association with RE has been less well studied. We analyzed data from 126 patients treated on 4 prospective clinical trials. Logistic regression models based on combinations of dosimetric factors [maximum dose to 2 cubic cm (D2cc) and generalized equivalent uniform dose (gEUD)], clinical variables, and pretreatment plasma levels of 30 cytokines were developed. Cross-validated estimates of area under the receiver operating characteristic curve (AUC) and log likelihood were used to assess prediction accuracy. Dose-only models predicted grade 3 RE with AUC values of 0.750 (D2cc) and 0.727 (gEUD). Combining clinical factors with D2cc increased the AUC to 0.779. Incorporating pretreatment cytokine measurements, modeled as direct associations with RE and as potential interactions with the dose-esophagitis association, produced AUC values of 0.758 and 0.773, respectively. D2cc and gEUD correlated with grade 3 RE with odds ratios (ORs) of 1.094/Gy and 1.096/Gy, respectively. Female gender was associated with a higher risk of RE, with ORs of 1.09 and 1.112 in the D2cc and gEUD models, respectively. Older age was associated with decreased risk of RE, with ORs of 0.992/year and 0.991/year in the D2cc and gEUD models, respectively. Combining clinical with dosimetric factors but not pretreatment cytokine levels yielded improved prediction of grade 3 RE compared to prediction by dose alone. Such multifactorial modeling may prove useful in directing radiation treatment planning.

Blood-based biomarkers for precision medicine in lung cancer: precision radiation therapy

Both tumors and patients are complex and models that determine survival and toxicity of radiotherapy or any other treatment ideally must take into account this variability as well as its dynamic state. The genetic features of the tumor and the host, and increasingly also the epi-genetic and proteomic characteristics, are being unraveled. Multiple techniques, including histological examination, blood sampling, measurement of circulating tumor cells (CTCs), and functional and molecular imaging, can be used for this purpose. However, the effects of radiation on the tumor and on organs at risk (OARs) are also influenced by the applied dose and volume of irradiated tissues. Combining all these biological, clinical, imaging, and dosimetric parameters in a validated prognostic or predictive model poses a major challenge. Here we aimed to provide an objective review of the potential of blood markers to guide high precision radiation therapy. A combined biological-mathematical approach opens new doors beyond prognostication of patients, as it allows truly precise oncological treatment. Indeed, the core for individualized and precision medicine is not only selection of patients, but even more the optimization of the therapeutic window on an individual basis. A holistic model will allow for determination of an individual dose-response relationship for each organ at risk for each tumor in each individual patient for the complete oncological treatment package. This includes, but is not limited to, radiotherapy alone. Individualized dose-response curves will allow for consideration of different doses of radiation and combinations with other drugs to plan for both optimal toxicity and complete response. Insights into the interactions between a multitude of parameters will lead to the discovery of new pathways and networks that will fuel new biological research on target discovery.

Radiation-induced lung toxicity in non-small-cell lung cancer: Understanding the interactions of clinical factors and cytokines with the dose-toxicity relationship

BACKGROUND AND PURPOSE

Current methods to estimate risk of radiation-induced lung toxicity (RILT) rely on dosimetric parameters. We aimed to improve prognostication by incorporating clinical and cytokine data, and to investigate how these factors may interact with the effect of mean lung dose (MLD) on RILT.

MATERIALS AND METHODS

Data from 125 patients treated from 2004 to 2013 with definitive radiotherapy for stages I-III NSCLC on four prospective clinical trials were analyzed. Plasma levels of 30 cytokines were measured pretreatment, and at 2 and 4weeks midtreatment. Penalized logistic regression models based on combinations of MLD, clinical factors, and cytokine levels were developed. Cross-validated estimates of log-likelihood and area under the receiver operating characteristic curve (AUC) were used to assess accuracy.

RESULTS

In prognosticating grade 3 or greater RILT by MLD alone, cross-validated log-likelihood and AUC were -28.2 and 0.637, respectively. Incorporating clinical features and baseline cytokine levels increased log-likelihood to -27.6 and AUC to 0.669. Midtreatment cytokine data did not further increase log-likelihood or AUC. Of the 30 cytokines measured, higher levels of 13 decreased the effect of MLD on RILT, corresponding to a lower odds ratio for RILT per Gy MLD, while higher levels of 4 increased the association.

CONCLUSIONS

Although the added prognostic benefit from cytokine data in our model was modest, understanding how clinical and biologic factors interact with the MLD-RILT relationship represents a novel framework for understanding and investigating the multiple factors contributing to radiation-induced toxicity.

Combing NLR, V20 and mean lung dose to predict radiation induced lung injury in patients with lung cancer treated with intensity modulated radiation therapy and chemotherapy

The purpose was to evaluate the predictive value of baseline neutrophil to lymphocyte ratio (NLR) level in the incidence of grade 3 or higher radiation induced lung injury (RILI) for lung cancer patients. A retrospectively analysis with 166 lung cancer patients was performed. All of the enrolled patients received chemoradiotherapy at our hospital between April 2014 and May 2016. The Cox proportional hazard model was used to identify the potential risk factors for RILI. In this cohort, the incidence of grade 3 or higher RILI was 23.8%. Univariate analysis showed that radiation dose, volume at least received 20Gy (V20), mean lung dose and NLR were significantly associated with the incidence of grade 3 or higher RILI (P = 0.012, 0.008, 0.012, and 0.039, respectively). Multivariate analysis revealed that total dose ≥ 60 Gy, V20 ≥ 20%, mean lung dose ≥ 12 Gy, and NLR ≥ 2.2 were still independent predictive factors for RILI (P = 0.010, 0.043, 0.028, and 0.015, respectively). A predictive model of RILI based on the identified risk factors was established using receiver operator characteristic curves. The results demonstrated that the combination analysis of V20, mean lung dose and NLR was superior to either of the variables alone. Additionally, we found that the constraint of V20 and mean lung dose were meaningful for patients with higher baseline NLR level. If the value of V20 and mean lung dose lower than the threshold value, the incidence of grade 3 or higher RILI for the high NLR level patients could be decreased from 63.3% to 8.7%. Our study showed that radiation dose, V20, mean lung dose and NLR were independent predictors for RILI. Combination analysis of V20, mean lung dose and NLR may provide a more accurate model for RILI prediction.

Neutrophil-lymphocyte ratio and a dosimetric factor for predicting symptomatic radiation pneumonitis in non-small-cell lung cancer patients treated with concurrent chemoradiotherapy

OBJECTIVES

To identify the factors that predict the progression of radiological radiation pneumonitis (RP) to symptomatic RP, and to evaluate the usefulness of the neutrophil-lymphocyte ratio (NLR) as a marker of RP severity and prognosis in stage III non-small cell lung cancer (NSCLC) patients treated with definitive concurrent chemoradiotherapy (CCRT).

MATERIALS AND METHODS

We retrospectively reviewed 61 patients treated between January 2010 and December 2015. Patients' demographic characteristics, clinical data, laboratory findings and treatment parameters were analyzed to determine the predictive factors associated with progression from radiological RP to symptomatic RP.

RESULTS

Forty-seven patients (77%) exhibited radiological RP at a median of 78 days after radiation therapy (RT) completion, and 15 (32%) of these patients developed symptomatic RP. The interval between RT completion and radiological RP presentation was shorter in patients who progressed to symptomatic RP (P = .001); progression was highly probable if this latency period was ≤2 months (P = .002). Stage and RT technique correlated with symptomatic RP development (P = .046 and P = .046, respectively). Among dosimetric factors, a V₂₀ (defined as the lung volume receiving ≥20 Gy) of >30% was the most significant predictor of symptomatic RP (P = .001). The NLR and C-reactive protein level at radiological RP were higher in patients who developed symptomatic RP (P = .067 and P = .012, respectively). On multivariate analysis, a V₂₀ >30% and an NLR at radiological RP >6 were associated with symptomatic RP development.

CONCLUSION

The NLR at radiological RP is a useful biomarker for predicting symptomatic RP development after CCRT in stage III NSCLC patients.

Pulmonary toxicity generated from radiotherapeutic treatment of thoracic malignancies

Radiation-induced lung injury (RILI) remains a major obstacle for thoracic radiotherapy for the treatment of lung cancer, esophageal cancer and lymphoma. It is the principal dose-limiting complication, and can markedly impair the therapeutic ratio as well as a patient's quality of life. The current review presents the relevant concepts associated with RILI, including the pathogenic mechanisms and the potential treatment strategies, so as to achieve a general understanding of this issue. RILI comprises an acute radiation pneumonitis phase and subsequent late lung fibrosis. The established assessment criteria are clinical manifestations, imaging changes and the necessity for medical assistance. Risk factors are also considered in order to optimize treatment planning. Due to the underlying molecular mechanisms of RILI, the present review also discusses several targeted pharmacological approaches for its treatment, as well as corticosteroid therapy.

Plasma Levels of IL-8 and TGF-β1 Predict Radiation-Induced Lung Toxicity in Non-Small Cell Lung Cancer: A Validation Study

PURPOSE AND OBJECTIVES

We previously reported that the combination of mean lung dose (MLD) and inflammatory cytokines interleukin-8 (IL-8) and transforming growth factor-β1 (TGF-β1) may provide a more accurate model for radiation-induced lung toxicity (RILT) prediction in 58 patients with non-small cell lung cancer (NSCLC). This study is to validate the previous findings with new patients and to explore new models with more cytokines.

METHODS AND MATERIALS

One hundred forty-two patients with stage I-III NSCLC treated with definitive radiation therapy (RT) from prospective studies were included. Sixty-five new patients were used to validate previous findings, and all 142 patients were used to explore new models. Thirty inflammatory cytokines were measured in plasma samples before RT and 2 weeks and 4 weeks during RT (pre, 2w, 4w). Grade ≥2 RILT was defined as grade 2, and higher radiation pneumonitis or symptomatic pulmonary fibrosis was the primary endpoint. Logistic regression was performed to evaluate the risk factors of RILT. The area under the curve (AUC) for the receiver operating characteristic curves was used for model assessment.

RESULTS

Sixteen of 65 patients (24.6%) experienced RILT2. Lower pre IL-8 and higher TGF-β1 2w/pre ratio were associated with higher risk of RILT2. The AUC increased to 0.73 by combining MLD, pre IL-8, and TGF-β1 2w/pre ratio compared with 0.61 by MLD alone to predict RILT. In all 142 patients, 29 patients (20.4%) experienced grade ≥2 RILT. Among the 30 cytokines measured, only IL-8 and TGF-β1 were significantly associated with the risk of RILT2. MLD, pre IL-8 level, and TGF-β1 2w/pre ratio were included in the final predictive model. The AUC increased to 0.76 by combining MLD, pre IL-8, and TGF-β1 2w/pre ratio compared with 0.62 by MLD alone.

CONCLUSIONS

We validated that a combination of mean lung dose, pre IL-8 level, and TGF-β1 2w/pre ratio provided a more accurate model to predict the risk of RILT2 compared with MLD alone.

Pulmonary injury associated with radiation therapy - Assessment, complications and therapeutic targets

Pulmonary injury is more common in patients undergoing radiation therapy for lungs and other thoracic malignancies. Recently with the use of most-advanced technologies powerful doses of radiation can be delivered directly to tumor site with exquisite precision. The awareness of technical and clinical parameters that influence the chance of radiation induced lung injury is important to guide patient selection and toxicity minimization strategies. At the cellular level, radiation activates free radical production, leading to DNA damage, apoptosis, cell cycle changes, and reduced cell survival. Preclinical research shows the potential for therapies targeting transforming growth factor-β (TGF-B), Toll like receptor (TLRs), Tumour necrosis factor-alpha (TNF-alpha), Interferon gamma (IFN-γ) and so on that may restore lung function. At present Amifostine (WR-2721) is the only approved broad spectrum radioprotector in use for patients undergoing radiation therapy. Newer techniques also offer the opportunity to identify new biomarkers and new targets for interventions to prevent or ameliorate these late effects of lung damage.

Genetic variants in the plasminogen activator inhibitor-1 gene are associated with an increased risk of radiation pneumonitis in lung cancer patients

Plasminogen activator inhibitor‐1 (PAI‐1) plays a crucial role in the process of lung injury, although its association with radiation pneumonitis (RP) is unclear. We hypothesized that genetic variants in PAI‐1 may influence the risk of RP. In this study, 169 lung cancer patients were genotyped for six single‐nucleotide polymorphisms in PAI‐1 using the Sequenom MassARRAY system. The risk of RP was evaluated by Cox proportional hazards analyses. The cumulative RP probabilities by genotype were assessed using Kaplan–Meier analyses. Univariate and multivariate analyses revealed that PAI‐1:rs7242 GT/GG was correlated with an increased occurrence of grade ≥3 RP (crude hazard ratio = 3.331; 95% confidence interval, 1.168–9.497; P = 0.024). Our results indicated that PAI‐1:rs7242 in the 3′‐untranslated region of PAI‐1 can be a predictor of grade ≥3 RP before radiotherapy.

Optimizing Radiotherapy with Immunotherapeutic Approaches

Several factors must be considered to successfully integrate immunotherapy with radiation into clinical practice. One such factor is that concepts arising from preclinical work must be tested in combination with radiation in preclinical models to better understand how combination therapy will work in patients; examples include checkpoint inhibitors, tumor growth factor-beta (TGF-β) inhibitors, and natural killer (NK) cell therapy. Also, many radiation fields and fractionation schedules typically used in radiation therapy had been standardized before the introduction of advanced techniques for radiation planning and delivery that account for changes in tumor size, location, and motion during treatment, as well as uncertainties introduced by variations in patient setup between treatment fractions. As a result, radiation therapy may involve the use of large treatment volumes, often encompassing nodal regions that may not be irradiated with more conformal techniques. Traditional forms of radiation in particular pose challenges for combination trials with immunotherapy. This chapter explores these issues in more detail and provides insights as to how radiation therapy can be optimized to combine with immunotherapy.

Radiogenomics: A systems biology approach to understanding genetic risk factors for radiotherapy toxicity?

Adverse reactions in normal tissue after radiotherapy (RT) limit the dose that can be given to tumour cells. Since 80% of individual variation in clinical response is estimated to be caused by patient-related factors, identifying these factors might allow prediction of patients with increased risk of developing severe reactions. While inactivation of cell renewal is considered a major cause of toxicity in early-reacting normal tissues, complex interactions involving multiple cell types, cytokines, and hypoxia seem important for late reactions. Here, we review 'omics' approaches such as screening of genetic polymorphisms or gene expression analysis, and assess the potential of epigenetic factors, posttranslational modification, signal transduction, and metabolism. Furthermore, functional assays have suggested possible associations with clinical risk of adverse reaction. Pathway analysis incorporating different 'omics' approaches may be more efficient in identifying critical pathways than pathway analysis based on single 'omics' data sets. Integrating these pathways with functional assays may be powerful in identifying multiple subgroups of RT patients characterised by different mechanisms. Thus 'omics' and functional approaches may synergise if they are integrated into radiogenomics 'systems biology' to facilitate the goal of individualised radiotherapy.