Carbon-ion Radiotherapy for Isolated Lymph Node Metastasis After Surgery or Radiotherapy for Lung Cancer

Five-Year Survival Outcomes After Carbon-Ion Radiotherapy for Operable Stage I NSCLC: A Japanese National Registry Study (J-CROS-LUNG)

INTRODUCTION

The standard therapy for stage I NSCLC is surgery, but some operable patients refuse this option and instead undergo radiotherapy. Carbon-ion radiotherapy (CIRT) is a type of radiotherapy. The Japanese prospective nationwide registry study on CIRT began in 2016. Here, we analyzed real-world clinical outcomes of CIRT for operable patients with stage I NSCLC.

METHODS

All patients with operable stage I NSCLC treated with CIRT in Japan between 2016 and 2018 were enrolled. The dose fractionations for CIRT were selected from several options approved by the Japanese Society for Radiation Oncology. CIRT was delivered to the primary tumor, not to lymph nodes.

RESULTS

The median follow-up period was 56 months. Among 136 patients, 117 (86%) had clinical stage IA NSCLC and 19 (14%) had clinical stage IB NSCLC. There were 50 patients (37%) diagnosed clinically without having been diagnosed histologically. Most tumors (97%) were located in the periphery. The 5-year overall survival, cause-specific survival, progression-free survival, and local control rate were 81.8% (95% confidence interval [CI]: 75.1-89.2), 91.2% (95% CI: 86.0-96.8), 65.9% (95% CI: 58.2-74.6), and 95.8% (95% CI: 92.3-99.5), respectively. Multivariate analysis identified age as a significant factor for overall survival (p = 0.018), whereas age and consolidation/tumor ratio (p = 0.010 and p = 0.004) were significant factors for progression-free survival. There was no grade 4 or higher toxicity. Grade 3 radiation pneumonitis occurred in one patient.

CONCLUSIONS

This study reports the long-term outcomes of CIRT for operable NSCLC in the real world. CIRT for operable patients has been found to have favorable outcomes, with tolerable toxicity.

Regulatory role of RGMb in lung injury promoted by the combination of carbon ion irradiation and anti-PD-1 antibody through Erk1/2 and p38 MAPK pathways

The combination of carbon ion radiotherapy and anti-PD-1 antibody represents a new approach to treating thoracic tumors. However, the lung damage caused by this combination therapy may limit its use, and the potential mechanisms for this are worthy of investigation. The objective of this research was to examine the potential involvement of repulsive guidance molecule b (RGMb) in lung damage promoted by the utilization of carbon ion irradiation combined with an anti-PD-1 antibody. The C57BL/6 mice have been randomly separated into four distinct groups: control, anti-PD-1, whole thorax carbon ion irradiation, and irradiation in combination with anti-PD-1 treatment groups (combination group). Detection of pathological changes in lung tissue using HE staining. Detection of pulmonary fibrosis by Masson staining and the hydroxyproline assay. ELISA to detect TNF-α, TGF-β, IL-6, and IL-1β expression levels within lung homogenates. The expression of RGMb, p38 MAPK, and Erk1/2 pathways was detected using a fully automated digital Western blotting system WES (ProteinSimple, USA). Flow cytometry was employed to analyze tissue-resident memory T cells (TRM) within the lung. Subsequently, the siRNA gene was employed to induce the downregulation of RGMb in mice in order to validate the involvement of RGMb in radiation-immune lung injury. The present study observed a significant increase in both inflammatory and fibrotic indicators within the mice group's lung tissue that received the combination treatment. The combination group exhibited elevated levels of TGF-β, TNF-α, IL-6, and IL-1β in lung homogenates. Anti-PD-1 antibody and carbon ion irradiation, upregulated RGMb, phospho-p38 MAPK and phospho-Erk1/2. The results obtained from the flow cytometry analysis indicated that the combination group was significantly higher in the number of clonal expansion TRMs, which were predominantly characterized by the expression of CD8+CD103+CD69-TRMs. The downregulate of RGMb via siRNA in mice resulted in a decrease in phospho-p38 MAPK and phospho-Erk1/2. The combination group exhibited a reduction in TNF-α, TGF-β, IL-6, and IL-1β in their lung tissues, and the number of CD8+CD103+CD69-TRM was significantly reduced. The combination group exhibited a significant improvement in inflammatory and fibrotic indicators within the lung tissues. Anti-PD-1 antibody and carbon ion irradiation synergistically regulate RGMb, leading to strong clonal expansion of lung TRM through the p38 MAPK and Erk1/2 pathways. The present study offers valuable insights into the treatment of lung injury due to the combined administration of carbon ion radiotherapy and anti-PD-1 antibody therapy.

Planning strategies for robust carbon-ion scanning radiotherapy for stage I esophageal cancer: a retrospective study

This study aimed to establish a treatment planning strategy with carbon-ion scanning radiotherapy (CIRTs) for stage I esophageal cancer. The clinical data of seven patients treated with CIRTs were used. The setup error and interfractional and intrafractional motion error were analyzed using in-room computed tomography (CT) images for each treatment day. Finally, the planning target volume (PTV) margin was identified according to the accuracy of the treatment system. To ensure robustness against the positional displacements of the target and organs at risk (OAR), the replacement areas were placed as a contour adjacent to the tumor or OAR on the CT-image. The CT values of these areas were replaced by those of the target or OAR. Further, the dose distributions were optimized. Moreover, the variations in the target coverage from the initial plan for each treatment day (ΔV95%) were evaluated. By contrast, the risk of OAR was not evaluated in this study. The setup error was within 1.0 mm. The interfractional and intrafractional target motion errors were 2.8 and 5.0 mm, respectively. The PTV margins were 6.5 and 6.8 mm in the axial and depth directions, respectively. The robustness to target and OAR displacement was evaluated. The results showed that the target coverage with replacement could suppress decreased target coverage more than that without replacement. The PTV determination and replacement methods used in this study improved the target coverage in CIRTs for stage I esophageal cancer. Despite the need for a clinical follow-up, this method may help to improve clinical outcomes.

METTL3-mediated m6A mRNA contributes to the resistance of carbon-ion radiotherapy in non-small-cell lung cancer

Lung cancer is one of the leading causes of death among cancer patients worldwide. Carbon-ion radiotherapy is a radical nonsurgical treatment with high local control rates and no serious adverse events. N6-methyladenosine (m6A) modification is one of the most common chemical modifications in eukaryotic messenger RNA (mRNA) and has important effects on the stability, splicing, and translation of mRNAs. Recently, the regulatory role of m6A in tumorigenesis has been recognized more and more. However, the dysregulation of m6A and its role in carbon-ion radiotherapy of non-small-cell lung cancer (NSCLC) remains unclear. In this study, we found that the level of methyltransferase-like 3 (METTL3) and its mediated m6A modification were elevated in NSCLC cells with carbon-ion radiotherapy. Knockdown of METTL3 in NSCLC cells impaired proliferation, migration, and invasion in vitro and in vivo. Moreover, we found that METTL3-mediated m6A modification of mRNA inhibited the decay of H2A histone family member X (H2AX) mRNA and enhanced its expression, which led to enhanced DNA damage repair and cell survival.

A Promising Treatment Strategy for Lung Cancer: A Combination of Radiotherapy and Immunotherapy

Lung cancer is a leading cause of cancer-related deaths worldwide despite advances in treatment. In the past few decades, radiotherapy has achieved outstanding technical advances and is being widely used as a definitive, prophylactic, or palliative treatment of patients with lung cancer. The anti-tumor effects of radiotherapy are considered to result in DNA damage in cancer cells. Moreover, recent evidence has demonstrated another advantage of radiotherapy: the induction of anti-tumor immune responses, which play an essential role in cancer control. In contrast, radiotherapy induces an immunosuppressive response. These conflicting reactions after radiotherapy suggest that maximizing immune response to radiotherapy by combining immunotherapy has potential to achieve more effective anti-tumor response than using each alone. Immune checkpoint molecules, such as cytotoxic T-lymphocyte-associated protein 4, programmed cell death-1/programmed death-ligand 1, and their inhibitors, have attracted significant attention for overcoming the immunosuppressive conditions in patients with cancer. Therefore, the combination of immune checkpoint inhibitors and radiotherapy is promising. Emerging preclinical and clinical studies have demonstrated the rationale for these combination strategies. In this review, we outlined evidence suggesting that combination of radiotherapy, including particle therapy using protons and carbon ions, with immunotherapy in lung cancer treatment could be a promising treatment strategy.

Machine Learning for the Prediction of Lymph Nodes Micrometastasis in Patients with Non-Small Cell Lung Cancer: A Comparative Analysis of Two Practical Prediction Models for Gross Target Volume Delineation

Purpose

The lymph node gross target volume (GTV) delineation in patients with non-small cell lung cancer (NSCLC) is crucial for prognosis. This study aimed to develop a predictive model that can be used to differentiate between lymph nodes micrometastasis (LNM) and non-lymph nodes micrometastasis (non-LNM).

Patients and Methods

A retrospective study involving 1524 patients diagnosed with NSCLC was collected in the First Hospital of Wuhan between January 1, 2017, and April 1, 2020. Duplicated and useless variables were excluded, and 16 candidate variables were selected for further analysis. The random forest (RF) algorithm and generalized linear (GL) algorithm were used to screen out the variables that greatly affected the LNM prediction, respectively. The area under the curve (AUC) was compared between the RF model and GL model.

Results

The RF model revealed that the variables, including pathology, degree of differentiation, maximum short diameter of lymph node, tumor diameter, pulmonary membrane invasion, clustered lymph nodes, and T stage, were more significant for LNM prediction. Multifactorial logistic regression analysis for the GL model indicated that vascular invasion, tumor diameter, degree of differentiation, pulmonary membrane invasion, and maximum standard uptake value (SUVmax) were positively associated with LNM. The AUC for the RF model and GL model was 0.83 (95% CI: 0.75 to 0.90) and 0.64 (95% CI: 0.60 to 0.70), respectively.

Conclusion

We successfully established an accurate and optimized RF model that could be used to predict LNM in patients with NSCLC. This model can be used to evaluate the risk of an individual patient experiencing LNM and therefore facilitate the choice of treatment.

Charged Particle and Conventional Radiotherapy: Current Implications as Partner for Immunotherapy

Radiotherapy (RT) has been shown to interfere with inflammatory signals and to enhance tumor immunogenicity via, e.g., immunogenic cell death, thereby potentially augmenting the therapeutic efficacy of immunotherapy. Conventional RT consists predominantly of high energy photon beams. Hypofractionated RT regimens administered, e.g., by stereotactic body radiation therapy (SBRT), are increasingly investigated in combination with cancer immunotherapy within clinical trials. Despite intensive preclinical studies, the optimal dose per fraction and dose schemes for elaboration of RT induced immunogenic potential remain inconclusive. Compared to the scenario of combined immune checkpoint inhibition (ICI) and RT, multimodal therapies utilizing other immunotherapy principles such as adoptive transfer of immune cells, vaccination strategies, targeted immune-cytokines and agonists are underrepresented in both preclinical and clinical settings. Despite the clinical success of ICI and RT combination, e.g., prolonging overall survival in locally advanced lung cancer, curative outcomes are still not achieved for most cancer entities studied. Charged particle RT (PRT) has gained interest as it may enhance tumor immunogenicity compared to conventional RT due to its unique biological and physical properties. However, whether PRT in combination with immune therapy will elicit superior antitumor effects both locally and systemically needs to be further investigated. In this review, the immunological effects of RT in the tumor microenvironment are summarized to understand their implications for immunotherapy combinations. Attention will be given to the various immunotherapeutic interventions that have been co-administered with RT so far. Furthermore, the theoretical basis and first evidences supporting a favorable immunogenicity profile of PRT will be examined.

Estimating the Number of Patients Eligible for Carbon Ion Radiotherapy in the United States

Purpose

Carbon ion radiotherapy (CIRT) is an emerging radiotherapy modality with potential advantages over conventional photon-based therapy, including exhibiting a Bragg peak and greater relative biological effectiveness, leading to a higher degree of cell kill. Currently, 13 centers are treating with CIRT, although there are no centers in the United States. We aimed to estimate the number of patients eligible for a CIRT center in the United States.

Materials and Methods

Using the National Cancer Database, we analyzed the incidence of cancers frequently treated with CIRT internationally (glioblastoma, hepatocellular carcinoma, cholangiocarcinoma, locally advanced pancreatic cancer, non-small cell lung cancer, localized prostate cancer, soft tissue sarcomas, and specific head and neck cancers) diagnosed in the United States in 2015. The percentage and number of patients likely benefiting from CIRT was estimated with inclusion criteria from clinical trials and retrospective studies, and that ratio was applied to 2019 cancer statistics. An adaption correction rate was applied to estimate the potential number of patients treated with CIRT. Given the high dependency on prostate and lung cancers and the uncertain adoption of CIRT in those diseases, the data were then reanalyzed excluding those diagnoses.

Results

Of the 1 127 455 new cases of cancer diagnosed in the United States in 2015, there were 213 073 patients (18.9%) eligible for treatment with CIRT based on inclusion criteria. When applying this rate and the adaption correction rate to the 2019 incidence data, an estimated 89 946 patients (42.2% of those fitting inclusion criteria) are eligible for CIRT. Excluding prostate and lung cancers, there were an estimated 8922 patients (10% of those eligible for CIRT) eligible for CIRT. The number of patients eligible for CIRT is estimated to increase by 25% to 27.7% by 2025.

Conclusion

Our analysis suggests a need for CIRT in the United States in 2019, with the number of patients possibly eligible to receive CIRT expected to increase during the coming 5 to 10 years.