Lung Stereotactic Body Radiation Therapy and Concurrent Immunotherapy: A Multicenter Safety and Toxicity Analysis

Immune checkpoint inhibitors with or without radiotherapy in metastatic non‑small cell lung cancer: A meta‑analysis and literature review

The combination of immune checkpoint inhibitors (ICIs) and radiotherapy has shown promise in the treatment of metastatic non-small cell lung cancer (NSCLC). The present meta-analysis aimed to determine the efficacy and safety of combining radiotherapy (RT) ICIs for the treatment of metastatic NSCLC. PubMed, Google Scholar, the Cochrane Library and Web of Science databases were searched for relevant articles up to February 1, 2023. Post-therapy outcomes such as progression-free survival (PFS), complete response, partial response (PR), progressive disease (PD), stable disease and adverse events (AEs) were analyzed. The meta-analysis was performed using RevMan 5.4 software. A total of seven studies involving 682 patients were included (384 patients who received ICI + RT vs. RT and 298 patients who received ICI + RT vs. ICI alone). No significant difference in PFS was demonstrated between the ICI + RT group and the RT group (heterogeneity: χ2=2.35; df=1; P=0.13; I2=57% and test for overall effect: Z=0.10; P=0.92). Conversely, patients in the ICI alone group had significantly decreased PR rates (heterogeneity: Τ2=0.00; χ2=2.13; df=3; P=0.54; I2=0% and test for overall effect: Z=2.57; P=0.01) compared with patients in the ICI + RT group. The ICI + RT group also had significantly lower rates of PD (heterogeneity: Τ2=0.00; χ2=0.91; df=3; P=0.82; I2=0% and test for overall effect: Z=2.52; P=0.01) compared with the ICI alone group. Safety analysis revealed no significant difference between patients who received ICI + RT and those who received RT in terms of grade 1 or 2 AEs. In conclusion, the combination of ICIs + RT demonstrates promising efficacy and safety for patients with metastatic NSCLC. However, clinical trials that have tested this combination are lacking, which emphasizes the need for further research.

A phase 2 single-arm trial of high-dose precision targeted radiotherapy added to immunotherapy for patients with metastatic non-small cell lung cancer

HYPOTHESIS

For metastatic non-small cell lung cancer (NSCLC), the addition of radiotherapy (RT) to immune checkpoint inhibitor (ICI) therapy could have synergistic anti-cancer effects and address the most threatening tumors. We posited that the addition of high-dose RT to ICI could prolong progression-free survival (PFS).

METHODS

In this single arm phase 2 trial, 45 patients with metastatic NSCLC who had received an anti-PD-1/anti-PD-L-1 ICI for 4+ weeks were enrolled from July 2017-May 2021. Patients received high-dose RT to 1-4 extracranial tumors and continued ICI until progression or unacceptable toxicity. The primary endpoint was PFS at 24 weeks, comparing to a historical control rate of 35%.

RESULTS

Of 44 evaluable patients, median age was 71, 75% had adenocarcinoma, 64% had polymetastatic disease, and 85% of cancers with known PD-L1 percentage were PD-L1 positive. Median number of treated tumors was two and most common dose was 40 Gy in 10 fractions (41/81 tumors). Median follow-up was 23.3 months. The trial met the primary outcome: 24-week PFS was 60% (95% CI 44-75%), higher than the historical control rate (p<0.001). Median PFS was 6.9 months (95% CI 4.0-13.5 mo) and median OS was 27.4 months (95% CI 20.4-not reached). Several patients with pre-study disease progression on ICI treatment achieved durable responses to study treatment, up to 53 months. Local recurrence rate was low: cumulative incidence of 5% at one, two, and three years. Two dose-limiting toxicities were observed (5%), including one grade 5 pneumonitis.

CONCLUSIONS

The strategy improved 24-week PFS compared to historical controls receiving ICI alone. The excellent local control supports the efficacy of high-dose RT in addressing macroscopic disease.

Tracheal necrosis after sandwich immunotherapy and stereotactic body radiotherapy for lung cancer

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Beyond success: unveiling the hidden potential of radiotherapy and immunotherapy in solid tumors

Immunotherapy, particularly with immune checkpoint inhibitors, has significantly transformed cancer treatment. Despite its success, many patients struggle to respond adequately or sustain long-lasting clinical improvement. A growing consensus has emerged that radiotherapy (RT) enhances the response rate and overall efficacy of immunotherapy. Although combining RT and immunotherapy has been extensively investigated in preclinical models and has shown promising results, establishing itself as a dynamic and thriving area of research, clinical evidence for this combination strategy over the past five years has shown both positive and disappointing results, suggesting the need for a more nuanced understanding. This review provides a balanced and updated analysis of the combination of immunotherapy and RT. We summarized the preclinical mechanisms through which RT boosts antitumor immune responses and mainly focused on the outcomes of recently updated clinical trials, including those that may not have met expectations. We investigated the optimization of the therapeutic potential of this combined strategy, including key challenges, such as fractionation and scheduling, lymph node irradiation, and toxicity. Finally, we offered insights into the prospects and challenges associated with the clinical translation of this combination therapy, providing a realistic perspective on the current state of research and potential future directions.

The dynamic duo: A narrative review on the synergy between stereotactic body radiotherapy and immunotherapy in lung cancer treatment (Review)

Immunotherapy, particularly immune checkpoint inhibitors (ICIs), is undoubtedly one of the major breakthroughs in lung cancer research. Patient survival and prognosis have all been improved as a result, although numerous patients do not respond to immunotherapy due to various immune escape mechanisms of the tumor cells. Recent preclinical and clinical evidence has shown that stereotactic body radiotherapy (SBRT), also known as stereotactic ablative radiotherapy, has a prominent immune priming effect that could elicit antitumor immunity against specific tumor antigens and destroy distant tumor cells, thereby achieving the elusive abscopal effect, with the resulting immuno‑active tumor environment also being more conducive to ICIs. Some landmark trials have already demonstrated the survival benefit of the dynamic duo of SBRT plus immunotherapy in metastatic non‑small‑cell lung cancer, while others such as PEMBRO‑RT further suggest that the addition of SBRT to immunotherapy could expand the current indication to those who have historically responded poorly to ICIs. In the present review, the biological mechanisms that drive the synergistic effect of SBRT and immunotherapy were first briefly outlined; then, the current understanding from clinical trials was summarized and new insight into the evolving role of immunotherapy and SBRT synergy in lung cancer treatment was provided. Finally, novel avenues for discovery were highlighted. The innovation of the present review lies in the inclusion of non‑ICI immunotherapy in the discussion, which provides a more comprehensive view on the current development and future trend of SBRT + immunotherapy synergy.

Evaluation of chest CT-scans following lung stereotactic ablative radiotherapy: Challenges and new insights

Stereotactic ablative radiotherapy (SABR) is increasingly used for the treatment of early-stage non-small cell lung cancer (ES-NSCLC) and for pulmonary metastases. In patients with ES-NSCLC, SABR is highly successful with reported 5-year local control rates of approximately 90%. However, the assessment of local control following lung SABR can be challenging as radiological changes arising from radiation-induced lung injury (RILI) can be observed in up to 90% of patients. These so-called 'benign' radiological changes evolve with time and are often asymptomatic. Several radiological and metabolic features have been explored to help distinguish RILI from local recurrences (LR). These include the Response Evaluation Criteria for Solid Tumors (RECIST), high-risk features (HRF's) and maximum standardized uptake value (SUVmax) on FDG-PET-CT. However, use of some of these approaches have poor predictive values and low specificity for recurrence. A proposed new workflow for the evaluation of post-lung SABR radiological changes will be reviewed which uses the presence of so-called 'actionable radiological features' to trigger changes to imaging schedules and identifies the need for a multidisciplinary board review. Furthermore, this critical review of post-lung SABR imaging will highlight current challenges, new insights, and unknowns in this field.

The Role of Thoracic Vertebral Body Dosimetry in Minimizing Acute Hematologic Toxicities of Patients With Non-Small Cell Lung Cancer Receiving Lung Radiation Therapy and Immunotherapy

PURPOSE

Hematologic toxicities (HTs) are among the most common toxicities of combined immunotherapy and radiation therapy (RT). It remains essential to prevent RT-induced HTs because they can cause treatment discontinuation (influencing antitumoral effects) and because lymphopenia might dampen the effects of immunotherapy. To date, there are no studies examining the effect of thoracic vertebral body (TVB) RT dose on HTs in patients with non-small cell lung cancer receiving combined lung RT and programmed cell death (ligand) 1 immunotherapy.

METHODS AND MATERIALS

For standardization, all doses were reported as 2-Gy equivalents (EQD2). Mirroring publications before the immunotherapy era, TVB volumes referred to T1-T10, and specific dosimetric parameters (DmeanEQD2, V5EQD2-V60EQD2) were analyzed. Logistic regression estimated associations between grade ≥3 HTs (HT3+) and dosimetric/clinical parameters. Normal tissue complication probability (NTCP) models were constructed by logistic regression analysis modeling for HT3+. Receiver operating characteristic (ROC) analysis delineated TVB dosimetric thresholds, the stratification of which was able to evaluate post-RT absolute lymphocyte count and immunotherapy responses. Areas under the curve (AUCs) for NTCP models were corroborated by bootstrapping (optimism-corrected) methodology.

RESULTS

In 132 patients, there were 26 (19.7%) instances of HT3+. On multivariate analysis, DmeanEQD2 and V5EQD2 to V20EQD2 were associated with HT3+ (P < .05 for all). The NTCP models illustrated a 50% probability of HT3+ at a DmeanEQD2 = 39.8 Gy, V5EQD2 = 87.4%, V10EQD2 = 77.0%, and V20EQD2 = 68.4%. ROC analysis delineated optimal thresholds of HT3+ with DmeanEQD2 ± 30.2 Gy, V5EQD2 ± 69.1%, V10EQD2 ± 64.6%, and V20EQD2 ± 53.5%. Patients treated with values above those cutoffs had over double the risk of HT3+, with significant differences in post-RT absolute lymphocyte count and immunotherapy responses (P < .05 for all). AUCs for each individual parameter ranged from 0.743 to 0.798, and combining all 4 aforementioned cutoffs into a ROC curve resulted in a qualitatively higher AUC (0.836).

CONCLUSIONS

This hypothesis-generating work suggests that TVB dosimetry may equate with HT3+ in patients with non-small cell lung cancer undergoing combined lung RT/immunotherapy. Applying TVB dose constraints in this population could reduce HT3+ and avoid dampening of immunotherapy responses, but prospective validation is required.

Hyperacute Radiation Pneumonitis after Severe irAE

A 54-year-old woman presented to an outpatient clinic with a recurrence of triple-negative breast cancer and multiple bone metastases. The patient had a large mass lesion of 10 cm on the sternum. She received the immune checkpoint inhibitors pembrolizumab and taxane. Initially, the patient responded excellently to treatment, but stopped pembrolizumab for grade IV skin toxicity with multiple ulcerative wounds over the bilateral leg and trunk. The lesions abated following administration of antibiotics and oral prednisolone for two months. After that, she was referred to the radiation oncology department for further treatment. She received radiotherapy for the sternum mass but stopped radiation at 42Gy/21 fractions for severe dyspnea and fever. Blood sampling found leukocytosis with neutrophil predominance. Chest radiography showed bilateral lung infiltration. Pulmonary CT scan yielded bilateral lung patchy consolidation compatible with radiation isodose-line. Bronchial lavage showed positive Pneumocystis jiroveci PCR. Dyspnea improved after titrating methylprednisolone within two days. The patient recovered well with TMP-SMX and glucocorticoids after the initiation of therapy.

Integration of dosimetric parameters, clinical factors, and radiomics to predict symptomatic radiation pneumonitis in lung cancer patients undergoing combined immunotherapy and radiotherapy

PURPOSE

This study aimed to combine clinical/dosimetric factors and handcrafted/deep learning radiomic features to establish a predictive model for symptomatic (grade ≥ 2) radiation pneumonitis (RP) in lung cancer patients who received immunotherapy followed by radiotherapy.

MATERIALS AND METHODS

This study retrospectively collected data of 73 lung cancer patients with prior receipt of ICIs who underwent thoracic radiotherapy (TRT). Of these 73 patients, 41 (56.2 %) developed symptomatic grade ≥ 2 RP. RP was defined per multidisciplinary clinician consensus using CTCAE v5.0. Regions of interest (ROIs) (from radiotherapy planning CT images) utilized herein were gross tumor volume (GTV), planning tumor volume (PTV), and PTV-GTV. Clinical/dosimetric (mean lung dose and V5-V30) parameters were collected, and 107 handcrafted radiomic (HCR) features were extracted from each ROI. Deep learning-based radiomic (DLR) features were also extracted based on pre-trained 3D residual network models. HCR models, Fusion HCR model, Fusion HCR + ResNet models, and Fusion HCR + ResNet + Clinical models were built and compared using the receiver operating characteristic (ROC) curve with measurement of the area under the curve (AUC). Five-fold cross-validation was performed to avoid model overfitting.

RESULTS

HCR models across various ROIs and the Fusion HCR model showed good predictive ability with AUCs from 0.740 to 0.808 and 0.740-0.802 in the training and testing cohorts, respectively. The addition of DLR features improved the effectiveness of HCR models (AUCs from 0.826 to 0.898 and 0.821-0.898 in both respective cohorts). The best performing prediction model (HCR + ResNet + Clinical) combined HCR & DLR features with 7 clinical/dosimetric characteristics and achieved an average AUC of 0.936 and 0.946 in both respective cohorts.

CONCLUSIONS

In patients undergoing combined immunotherapy/RT for lung cancer, integrating clinical/dosimetric factors and handcrafted/deep learning radiomic features can offer a high predictive capacity for RP, and merits further prospective validation.

Effect of Sequence of Radiotherapy Combined With Immunotherapy on the Incidence of Pneumonitis in Patients With Lung Cancer: A Systematic Review and Network Meta-Analysis

BACKGROUND

With the widespread application of immune checkpoint inhibitor (ICI) combined with radiotherapy (RT) for the treatment of lung cancer, increasing attention has been paid to treatment-related pneumonitis. The effect of the treatment sequence on the incidence of pneumonitis remains unclear.

METHODS

We searched databases including PubMed, Embase, and ClinicalTrials.gov, meeting abstracts, and reference lists of relevant review articles for literature published on radio- and immunotherapy in lung cancer. Stata software (version 16.0) was used for meta-analysis. Data on the incidence of any grade and ≥ grade 3 pneumonitis was pooled using the random effects model. Bayesian network meta-analysis was used for arm-based pairwise comparisons. Subgroup analyses were performed to identify the potential influencing factors.

RESULTS

Thirty-eight studies met our inclusion criteria. The network meta-analysis showed no significant difference between the incidence of pneumonitis in concurrent ICI with RT (concurrent arm) and RT followed by ICI (RT-first arm) (odds ratio [OR]: 0.71, 95% confidence interval [CI]: 0.10-4.81). In the meta-analysis of single group rates, RT following ICI (ICI-first arm) exhibited higher incidence of any grade pneumonitis compared with concurrent- and RT-first arms, with 0.321 (95% CI: 0.260-0.386) for programmed cell death protein 1 (PD-1) inhibitors from clinical trials, and 0.480 (95% CI: 0.363-0.598) for PD-1 inhibitors from real-world retrospective data, respectively.

CONCLUSION

No significant difference in the incidence of any grade and grade ≥ 3 pneumonitis was found between RT-first and concurrent arms. The ICI-first arm exhibited a higher incidence of pneumonitis, which needs to be further confirmed by follow-up studies.

Long-term outcomes of metastasis-directed stereotactic body radiation therapy in metastatic nasopharyngeal carcinoma

BACKGROUND

The study aims to evaluate the outcomes of metastasis-directed stereotactic body radiation therapy (SBRT) in metastatic nasopharyngeal carcinoma (mNPC).

METHODS

We reviewed all SBRT conducted in patients with mNPC in our institution between 2013 and 2022. Systemic therapy was performed with chemotherapy with or without anti-programmed death-1 (PD-1) therapy. Local treatment delivered with ablative purpose in stereotactic setting with dose/fraction ≥5 Gy was evaluated. Kaplan-Meier analyses were used to determine the rates of local control (LC), progression-free survival (PFS), and overall survival (OS). Univariate and multivariate analyses were performed by Cox regression.

RESULTS

A total of 54 patients with 76 metastatic sites receiving SBRT were analyzed. Median follow-up was 49 months. The 3-year LC, PFS, and OS rates were 89.1%, 29.4%, and 57.9%, respectively. Adding a PD-1 inhibitor to SBRT tended to prolong median OS (50.1 vs. 32.2 months, p = 0.068). Patients receiving a biological effective dose (BED, α/β = 10) ≥ 80 Gy had a significantly longer median OS compared to those who received a lower dose (not reached vs. 29.5 months, p = 0.004). Patients with oligometastases (1-5 metastases) had a better median OS (not reached vs. 29.5 months, p < 0.001) and PFS (34.3 vs. 4.6 months, p < 0.001). Pretreatment EBV-DNA and maintenance therapy were also significant predictors for OS.

CONCLUSIONS

Metastatic NPC patients could benefit from metastases-directed SBRT in combination with systemic therapy.

[Impact of immunotherapy on the therapeutic strategy for the management of stage I non-small cell lung cancer: The radiation oncologist's point of view]

Surgery is the standard treatment for operable patients with stage I non-small cell lung cancer (NSCLC) (T1-T2aN0M0). Stereotactic body radiotherapy (SBRT) is the treatment of choice for non-operable patients, and its positioning for operable patients remains to be clarified. The pattern of recurrence after management of stage I NSCLC is dominated by the risk of distant recurrence, this constituting the rationale for the adjunction of systemic treatment, and especially check point inhibitor (CPI), in combination with surgery or SBRT for patients with high risk features. While the benefit of postoperative CPI on the micro-metastatic disease is logically considered within the framework of a simply additive effect of both therapeutic modalities, it is reasonable to consider a synergistic effect of both CPI and SBRT. Given the role of tumor draining nodes in the development of an anti-tumor immune response, a "tumor-draining node sparing" strategy enabled by SBRT could therefore be of major interest in combination with CPI. Pending confirmation of the role of CPI in combination with RTS for the management of stage I NSCLC, we thus discuss in this review the theoretical advantages that this therapeutic strategy could have compared to a surgical strategy.

Ultra-high dose-rate proton FLASH improves tumor control

BACKGROUND AND PURPOSE

Proton radiotherapy (PRT) offers potential benefits over other radiation modalities, including photon and electron radiotherapy. Increasing the rate at which proton radiation is delivered may provide a therapeutic advantage. Here, we compared the efficacy of conventional proton therapy (CONVpr) to ultrahigh dose-rate proton therapy, FLASHpr, in a mouse model of non-small cell lung cancers (NSCLC).

MATERIALS AND METHODS

Mice bearing orthotopic lung tumors received thoracic radiation therapy using CONVpr (<0.05 Gy/s) and FLASHpr (>60 Gy/s) dose rates.

RESULTS

Compared to CONVpr, FLASHpr was more effective in reducing tumor burden and decreasing tumor cell proliferation. Furthermore, FLASHpr was more efficient in increasing the infiltration of cytotoxic CD8+ T-lymphocytes inside the tumor while simultaneously reducing the percentage of immunosuppressive regulatory T-cells (Tregs) among T-lymphocytes. Also, compared to CONVpr, FLASHpr was more effective in decreasing pro-tumorigenic M2-like macrophages in lung tumors, while increasing infiltration of anti-tumor M1-like macrophages. Finally, FLASHpr treatment reduced expression of checkpoint inhibitors in lung tumors, indicating reduced immune tolerance.

CONCLUSIONS

Our results suggest that FLASH dose-rate proton delivery modulates the immune system to improve tumor control and might thus be a promising new alternative to conventional dose rates for NSCLC treatment.

Re-evaluating the risk factors for radiation pneumonitis in the era of immunotherapy

As one of the common complications of radiotherapy, radiation pneumonia (RP) limits the prognosis of patients. Therefore, better identifying the high-risk factors that lead to RP is essential to effectively prevent its occurrence. However, as lung cancer treatment modalities are being replaced and the era of immunotherapy has arrived, literature that reviews the parameters and mode of radiotherapy, chemotherapy drugs, targeted drugs and current hot immune checkpoint inhibitors related to RP is lacking. This paper summarizes the risk factors for radiation pneumonia by retrieving and analysing previously published literature and the results of large clinical trials. The literature primarily included retrospective analyses, including clinical trials in different periods and a part of the literature review. A systematic literature search of Embase, PubMed, Web of Science, and Clinicaltrials.gov was performed for relevant publications up to 6 Dec. 2022. Search keywords include, but are not limited to, "radiation pneumonia", "pneumonia", "risk factors", "immunotherapy", etc. The factors related to RP in this paper include physical parameters of radiotherapy, including V₅, V₂₀, and MLD; chemoradiotherapy mode and chemotherapy drugs, including paclitaxel and gemcitabine; EGFR-TKI; ALK inhibitors; antiangiogenic drugs; immune drugs and the underlying disease of the patient. We also introduce the possible mechanism of RP. In the future, we hope that this article not only sounds the alarm for clinicians but also helps to identify a method that can effectively intervene and reduce the occurrence of RP, significantly improve the quality of life and prognosis of patients, and more effectively improve the therapeutic effect of radiation therapy.

Radiation combined with immune checkpoint inhibitors for unresectable locally advanced non-small cell lung cancer: synergistic mechanisms, current state, challenges, and orientations

Until the advent of immune checkpoint inhibitors (ICIs), definitive radiotherapy (RT) concurrently with chemotherapy was recommended for unresectable, locally advanced non-small cell lung cancer (LA-NSCLC). The trimodality paradigm with consolidation ICIs following definitive concurrent chemoradiotherapy has been the standard of care since the PACIFIC trial. Preclinical evidence has demonstrated the role of RT in the cancer-immune cycle and the synergistic effect of RT combined with ICIs (iRT). However, RT exerts a double-edged effect on immunity and the combination strategy still could be optimized in many areas. In the context of LA-NSCLC, optimized RT modality, choice, timing, and duration of ICIs, care for oncogenic addicted tumors, patient selection, and novel combination strategies require further investigation. Targeting these blind spots, novel approaches are being investigated to cross the borders of PACIFIC. We discussed the development history of iRT and summarized the updated rationale for the synergistic effect. We then summarized the available research data on the efficacy and toxicity of iRT in LA-NSCLC for cross-trial comparisons to eliminate barriers. Progression during and after ICIs consolidation therapy has been regarded as a distinct resistance scenario from primary or secondary resistance to ICIs, the subsequent management of which has also been discussed. Finally, based on unmet needs, we probed into the challenges, strategies, and auspicious orientations to optimize iRT in LA-NSCLC. In this review, we focus on the underlying mechanisms and recent advances of iRT with an emphasis on future challenges and directions that warrant further investigation. Taken together, iRT is a proven and potential strategy in LA-NSCLC, with multiple promising approaches to further improve the efficacy. Video Abstract.

A Risk-Scoring Model for Severe Checkpoint Inhibitor-Related Pneumonitis: A Case-Control Study

BACKGROUND AND OBJECTIVE

Checkpoint inhibitor-related pneumonitis (CIP) is one of the most common serious and fatal adverse events associated with immune checkpoint inhibitors (ICIs). The study sought to identify risk factors of all-grade and severe CIP and to construct a risk-scoring model specifically for severe CIP.

METHODS

This observational, retrospective case-control study involved 666 lung cancer patients who received ICIs between April 2018 and March 2021. The study analyzed patient demographic, preexisting lung diseases, and the characteristics and treatment of lung cancer to determine the risk factors for all-grade and severe CIP. A risk score for severe CIP was developed and validated in a separate patient cohort of 187 patients.

RESULTS

Among 666 patients, 95 patients were afflicted with CIP, of which 37 were severe cases. Multivariate analysis revealed age ≥ 65 years, current smoking, chronic obstructive pulmonary disease, squamous cell carcinoma, prior thoracic radiotherapy, and extra-thoracic radiotherapy during ICI were independently associated with CIP events. Five factors, emphysema (odds ratio [OR] 2.87), interstitial lung disease (OR 4.76), pleural effusion (OR 3.00), history of radiotherapy during ICI (OR 4.30), and single-agent immunotherapy (OR 2.44) were independently associated with severe CIP and were incorporated into a risk-score model (score ranging 0-17). The area under the model receiver operating characteristic curve for the model was 0.769 in the development cohort and 0.749 in the validation cohort.

CONCLUSIONS

The simple risk-scoring model may predict severe CIP in lung cancer patients receiving ICIs. For patients with high scores, clinicians should use ICIs with caution or strengthen the monitoring of these patients.

Four-Dimensional Computed Tomography Ventilation Image-Guided Lung Functional Avoidance Radiation Therapy: A Single-Arm Prospective Pilot Clinical Trial

PURPOSE

The primary objective of this prospective pilot trial was to assess the safety and feasibility of lung functional avoidance radiation therapy (RT) with 4-dimensional (4D) computed tomography (CT) ventilation imaging.

METHODS AND MATERIALS

Patients with primary lung cancer or metastatic disease to the lungs to receive conventionally fractionated RT (CFRT) or stereotactic body RT (SBRT) were eligible. Standard-of-care 4D-CT scans were used to generate ventilation images through image processing/analysis. Each patient required a standard intensity modulated RT plan and ventilation image guided functional avoidance plan. The primary endpoint was the safety of functional avoidance RT, defined as the rate of grade ≥3 adverse events (AEs) that occurred ≤12 months after treatment. Protocol treatment was considered safe if the rates of grade ≥3 pneumonitis and esophagitis were <13% and <21%, respectively for CFRT, and if the rate of any grade ≥3 AEs was <28% for SBRT. Feasibility of functional avoidance RT was assessed by comparison of dose metrics between the 2 plans using the Wilcoxon signed-rank test.

RESULTS

Between May 2015 and November 2019, 34 patients with non-small cell lung cancer were enrolled, and 33 patients were evaluable (n = 24 for CFRT; n = 9 for SBRT). Median follow-up was 14.7 months. For CFRT, the rates of grade ≥3 pneumonitis and esophagitis were 4.2% (95% confidence interval, 0.1%-21.1%) and 12.5% (2.7%-32.4%). For SBRT, no patients developed grade ≥3 AEs. Compared with the standard plans, the functional avoidance plans significantly (P < .01) reduced the lung dose-function metrics without compromising target coverage or adherence to standard organs at risk constraints.

CONCLUSIONS

This study, representing one of the first prospective investigations on lung functional avoidance RT, demonstrated that the 4D-CT ventilation image guided functional avoidance RT that significantly reduced dose to ventilated lung regions could be safely administered, adding to the growing body of evidence for its clinical utility.

Metastases-directed stereotactic body radiotherapy in combination with targeted therapy or immunotherapy: systematic review and consensus recommendations by the EORTC-ESTRO OligoCare consortium

Stereotactic body radiotherapy (SBRT) for patients with metastatic cancer, especially when characterised by a low tumour burden (ie, oligometastatic disease), receiving targeted therapy or immunotherapy has become a frequently practised and guideline-supported treatment strategy. Despite the increasing use in routine clinical practice, there is little information on the safety of combining SBRT with modern targeted therapy or immunotherapy and a paucity of high-level evidence to guide clinical management. A systematic literature review was performed to identify the toxicity profiles of combined metastases-directed SBRT and targeted therapy or immunotherapy. These results served as the basis for an international Delphi consensus process among 28 interdisciplinary experts who are members of the European Society for Radiotherapy and Oncology (ESTRO) and European Organisation for Research and Treatment of Cancer (EORTC) OligoCare consortium. Consensus was sought about risk mitigation strategies of metastases-directed SBRT combined with targeted therapy or immunotherapy; a potential need for and length of interruption to targeted therapy or immunotherapy around SBRT delivery; and potential adaptations of radiation dose and fractionation. Results of this systematic review and consensus process compile the best available evidence for safe combination of metastases-directed SBRT and targeted therapy or immunotherapy for patients with metastatic or oligometastatic cancer and aim to guide today's clinical practice and the design of future clinical trials.

Progress in diagnosis and treatment of checkpoint inhibitor pneumonitis

PURPOSE OF REVIEW

In this article, we summarized the current knowledge of the diagnosis and treatment of the checkpoint inhibitor pneumonitis (CIP), and provide an outlook on the current issues and future prospects.

RECENT FINDINGS

Pulmonary toxicity of immunotherapy covers a broad range of pulmonary manifestations and is often referred to as pneumonitis. It is a severe and potentially life-threatening immune-related adverse events (irAEs) that requires early identification and management. The diagnosis of CIP should be carefully distinguished from other forms of pulmonary diseases. Recognizing risk factors and typical symptoms helps to raise suspicion of CIP. Further characterization of the unique radiographic and pathological features is warranted to expedite diagnosis. The identification of potential biomarkers for CIP is emerging and has great relevance in the clinic. Multidisciplinary collaborations involving oncologists, radiologists and pulmonologists may facilitate uniform management strategies. Treatment discontinuation is the mainstay for treating CIP of all grades. Systemic steroids are considered for pneumonitis at least grade 2 and immunosuppressive drugs are recommended for CIP patients refractory to steroids. In the future, more diagnosis and management strategies are needed to provide new insights and treatment options.

SUMMARY

There are achievements and shortcomings in the current status of the diagnosis and treatment for CIP. In the future, the research on this topic should be further demonstrated.

Research Progress on Radiotherapy Combined with Immunotherapy for Associated Pneumonitis During Treatment of Non-Small Cell Lung Cancer

Radiation pneumonitis is a common and serious complication of radiotherapy for thoracic tumours. Although radiotherapy technology is constantly improving, the incidence of radiation pneumonitis is still not low, and severe cases can be life-threatening. Once radiation pneumonitis develops into radiation fibrosis (RF), it will have irreversible consequences, so it is particularly important to prevent the occurrence and development of radiation pneumonitis. Immune checkpoint inhibitors (ICIs) have rapidly altered the treatment landscape for multiple tumour types, providing unprecedented survival in some patients, especially for the treatment of non-small cell lung cancer (NSCLC). However, in addition to its remarkable curative effect, ICls may cause immune-related adverse events. The incidence of checkpoint inhibitor pneumonitis (CIP) is 3% to 5%, and its mortality rate is 10% to 17%. In addition, the incidence of CIP in NSCLC is higher than in other tumour types, reaching 7%–13%. With the increasing use of immune checkpoint inhibitors (ICls) and thoracic radiotherapy in the treatment of patients with NSCLC, ICIs may induce delayed radiation pneumonitis in patients previously treated with radiation therapy, or radiation activation of the systemic immune system increases the toxicity of adverse reactions, which may lead to increased pulmonary toxicity and the incidence of pneumonitis. In this paper, the data about the occurrence of radiation pneumonitis, immune pneumonitis, and combined treatment and the latest related research results will be reviewed.

Outcome of lung oligometastatic patients treated with stereotactic body irradiation

Purpose

The oligometastatic stage is an intermediate stage of cancer between the localized stage and polymetastatic stage. The prognosis of patients in this stage also appears to be intermediate. Lung stereotactic body radiotherapy is a possible tool for treating oligometastatic lung sites. The objective of our study was to evaluate the clinical outcomes in terms of local control, progression-free survival, overall survival, and toxicity of SBRT in oligometastatic patients with lung metastases from any solid primary tumor.

Materials and methods

Clinical records of consecutive lung oligometastatic patients treated between January 2010 and December 2020 for lung SBRT at 60 Gy in 3- or 8-fraction schedules and a controlled primary tumor were retrospectively analyzed.

Results

After a median follow-up of 20.3 months, local failure occurred for 14 lesions, 57 patients experienced lung progression, and 64 patients experienced disease progression. Overall survival rates at 1 and 2 years were 85.6 and 69.7%, respectively. Fifty-two patients experienced radiation pneumonitis, but only 2 patients were symptomatic and presented grade 2 late pneumonitis. No grade 3-4 toxicity was observed. ECOG 0 was the only prognostic factor for overall survival (HR = 3.5; 95% CI 3.2-3.8; p < 0.01).

Conclusion

SBRT with a 60-Gy schedule in 8 fractions is an effective and well-tolerated treatment for patients with lung oligometastases from any solid primary tumor.

The oligometastatic spectrum in the era of improved detection and modern systemic therapy

Metastases remain the leading cause of cancer-related mortality. The oligometastasis hypothesis postulates that a spectrum of metastatic spread exists and that some patients with a limited burden of metastases can be cured with ablative therapy. Over the past decade, substantial advances in systemic therapies have resulted in considerable improvements in the outcomes of patients with metastatic cancers, warranting re-examination of the oligometastatic paradigm and the role of local ablative therapies within the context of the improved therapeutic responses, shifting patterns of disease recurrence and possible synergy with systemic treatments. Herein, we reframe the oligometastatic phenotype as a dynamic state for which locally ablative, metastasis-directed therapy improves clinical outcomes, including by prolonging survival and increasing cure rates. Important risk factors defining the metastatic spectrum are highlighted that inform both staging and therapy. Finally, we synthesize the literature on combining local therapies with modern systemic treatments, identifying general themes to optimally integrate ablative therapies in this context.

Predictors of Pneumonitis in Combined Thoracic Stereotactic Body Radiotherapy and Immunotherapy

PURPOSE

Thoracic stereotactic body radiotherapy (SBRT) is associated with high rates of local control but carries a risk of pneumonitis. Immunotherapy is a standard treatment for patients with metastatic disease but can also cause pneumonitis. To evaluate the feasibility and safety of thoracic SBRT with systemic immunotherapy, clinical outcomes of patients treated with immune checkpoint blockade (ICB) and SBRT on prospective trials were reviewed.

METHODS AND MATERIALS

Three consecutive phase 1 trials of combination SBRT and ICB conducted between 2016-2020 for widely metastatic solid tumors were reviewed. The protocols mandated adherence to NRG BR001/BR002 OAR constraints, resulting in <100% coverage of some target volumes. ICB was administered either sequentially (within 7 days after completion of SBRT) or concurrently (before or at the start of SBRT), depending on protocol. Endpoints included pneumonitis, dose-volume constraints, local failure, and overall survival (OS). The cumulative incidence estimator and Kaplan-Meier method were used.

RESULTS

123 patients met eligibility with 311 metastases irradiated. The most common histologies included non-small cell lung cancer (33%) and colorectal cancer (12%). Median follow up was 12 months. The overall rate of grade 3+ pneumonitis was 8.1%. 1-year local failure was 3.6%. Established dosimetric parameters were significantly associated with the development of pneumonitis (p<0.05). In most patients, the lungs were not challenged with high doses of radiation, defined as receiving ≥75% of the maximum for a given lung dose-volume constraint. Patients who were challenged were not found to have a significantly higher risk of pneumonitis.

CONCLUSIONS

In the largest series of thoracic SBRT and immunotherapy, local control was excellent with acceptable toxicity and support the conclusion that established dose-volume constraints for the lung are safe. However, these results highlight the potential value in reporting of OARs being challenged with doses approaching protocol specified limits.

Dosimetric Risk Factors for Acute Radiation Pneumonitis in Patients With Prior Receipt of Immune Checkpoint Inhibitors

Purpose

Dosimetric parameters (e.g., mean lung dose (MLD), V20, and V5) can predict radiation pneumonitis (RP). Constraints thereof were formulated before the era of combined immune checkpoint inhibitors (ICIs) and radiotherapy, which could amplify the RP risk. Dosimetric predictors of acute RP (aRP) in the context of ICIs are urgently needed because no data exist thus far.

Methods and Materials

All included patients underwent thoracic intensity-modulated radiotherapy, previously received ICIs, and followed-up at least once. Logistic regression models examined predictors of aRP (including a priori evaluation of MLD, V20, and V5), and their discriminative capacity was assessed by receiver operating characteristic analysis.

Results

Median follow-up of the 40 patients was 5.3 months. Cancers were lung (80%) or esophageal (20%). ICIs were PD-1 (85%) or PD-L1 (15%) inhibitors (median 4 cycles). Patients underwent definitive (n=19), consolidative (n=14), or palliative (n=7) radiotherapy; the median equivalent dose in 2 Gy fractions (EQD2) was 60 Gy (IQR, 51.8-64 Gy). Grades 1-5 aRP occurred in 25%, 17.5%, 15%, 2.5%, and 5%, respectively. The only variables associated with any-grade aRP were V20 (p=0.014) and MLD (p=0.026), and only V20 with grade ≥2 aRP (p=0.035). Neither the number of prior ICI cycles nor the delivery of concurrent systemic therapy significantly associated with aRP risk. Graphs were constructed showing the incrementally increasing risk of aRP based on V20 and MLD (continuous variables).

Conclusions

This is the first study illustrating that V20 and MLD may impact aRP in the setting of prior ICIs. However, these data should not be extrapolated to patients without pre-radiotherapy receipt of prior ICIs, or to evaluate the risk of chronic pulmonary effects. If these results are validated by larger studies with more homogeneous populations, the commonly accepted V20/MLD dose constraints could require revision if utilized in the setting of ICIs.

A Combined Model to Improve the Prediction of Local Control for Lung Cancer Patients Undergoing Stereotactic Body Radiotherapy Based on Radiomic Signature Plus Clinical and Dosimetric Parameters

PURPOSE

Stereotactic body radiotherapy (SBRT) is an important treatment modality for lung cancer patients, however, tumor local recurrence rate remains some challenge and there is no reliable prediction tool. This study aims to develop a prediction model of local control for lung cancer patients undergoing SBRT based on radiomics signature combining with clinical and dosimetric parameters.

METHODS

The radiomics model, clinical model and combined model were developed by radiomics features, incorporating clinical and dosimetric parameters and radiomics signatures plus clinical and dosimetric parameters, respectively. Three models were established by logistic regression (LR), decision tree (DT) or support vector machine (SVM). The performance of models was assessed by receiver operating characteristic curve (ROC) and DeLong test. Furthermore, a nomogram was built and was assessed by calibration curve, Hosmer-Lemeshow and decision curve.

RESULTS

The LR method was selected for model establishment. The radiomics model, clinical model and combined model showed favorite performance and calibration (Area under the ROC curve (AUC) 0.811, 0.845 and 0.911 in the training group, 0.702, 0.786 and 0.818 in the validation group, respectively). The performance of combined model was significantly superior than the other two models. In addition, Calibration curve and Hosmer-Lemeshow (training group: P = 0.898, validation group: P = 0.891) showed good calibration of combined nomogram and decision curve proved its clinical utility.

CONCLUSIONS

The combined model based on radiomics features plus clinical and dosimetric parameters can improve the prediction of 1-year local control for lung cancer patients undergoing SBRT.

Evaluation of Lung Tumor Target Volume in a Large Sample: Target and Clinical Factors Influencing the Volume Derived From Four-Dimensional CT and Cone Beam CT

Background and Purpose

This study aimed to systematically evaluate the influence of target-related and clinical factors on volume differences and the similarity of targets derived from four-dimensional computed tomography (4DCT) and cone beam computed tomography (CBCT) images in lung stereotactic body radiation therapy (SBRT).

Materials and Methods

4DCT and CBCT image data of 210 tumors from 195 patients were analyzed. The internal gross target volume (IGTV) derived from the maximum intensity projection (MIP) of 4DCT (IGTV-MIP) and the IGTV from CBCT (IGTV-CBCT) were compared with the reference IGTV from 10 phases of 4DCT (IGTV-10). The target size, tumor motion, and the similarity between IGTVs were measured. The influence of target-related and clinical factors on the adequacy of IGTVs derived from 4DCT MIP and CBCT images was evaluated.

Results

The mean tumor motion amplitude in the 3D direction was 6.5 ± 5 mm. The mean size ratio of IGTV-CBCT and IGTV-MIP compared to IGTV-10 in all patients was 0.71 ± 0.21 and 0.8 ± 0.14, respectively. Female sex, greater BSA, and larger target size were protective factors, while the Karnofsky Performance Status, body mass index, and motion were risk factors for the similarity between IGTV-MIP and IGTV-10. Older age and larger target size were protective factors, while adhesion to the heart, coexistence with cardiopathy, and tumor motion were risk factors for the similarity between IGTV-CBCT and IGTV-10.

Conclusion

Clinical factors should be considered when using MIP images for defining ITV, and when using CBCT images for verifying treatment targets.

Influence of target dose heterogeneity on dose sparing of normal tissue in peripheral lung tumor stereotactic body radiation therapy

OBJECTIVE

To evaluate the influence of target dose heterogeneity on normal tissue dose sparing for peripheral lung tumor stereotactic body radiation therapy (SBRT).

METHODS

Based on the volumetric-modulated arc therapy (VMAT) technique, three SBRT plans with homogeneous, moderate heterogeneous, and heterogeneous (HO, MHE, and HE) target doses were compared in 30 peripheral lung tumor patients. The prescription dose was 48 Gy in 4 fractions. Ten rings outside the PTV were created to limit normal tissue dosage and evaluate dose falloff.

RESULTS

When MHE and HE plans were compared to HO plans, the conformity index of the PTV was increased by approximately 0.08. The median mean lung dose (MLD), V₅, V₁₀, V₂₀ of whole lung, D_2%, D_1cc, D_2cc of the rib, V₃₀ of the rib, D_2% and the maximum dose (D_max) of the skin, and D_2% and D_max of most mediastinal organs at risk (OARs) and spinal cord were reduced by up to 4.51 Gy or 2.8%. Analogously, the median D_max, D_2% and mean dose of rings were reduced by 0.71 to 8.46 Gy; and the median R_50% and D_2cm were reduced by 2.1 to 2.3 and 7.4% to 8.0%, respectively. Between MHE and HE plans there was little to no difference in OARs dose and dose falloff beyond the target. Furthermore, the dose sparing of rib V₃₀ and the mean dose of rings were negatively correlated with the rib and rings distance from tumor, respectively.

CONCLUSIONS

For peripheral lung tumor SBRT, target conformity, normal tissue dose, and dose falloff around the target could be improved by loosening or abandoning homogeneity. While there was negligible further dose benefit for the maximum target dose above 125% of the prescription, dose sparing of normal tissue derived from a heterogeneous target decreased as the distance from the tumor increased.

A narrative review of combined stereotactic ablative radiotherapy and immunotherapy in metastatic non-small cell lung cancer

Immune checkpoint inhibitors (ICIs) have significantly improved overall survival (OS) in metastatic non-small cell lung cancer (m-NSCLC). However, not all patients with m-NSCLC benefit from ICIs, and resistance to ICIs is an emerging challenge. The tumour microenvironment (TME) is immunosuppressive, and provides a myriad of mechanisms to facilitate escape of cancer cells from immune surveillance. The TME may also dampen the response to ICIs by inhibiting T cell effector responses. The poor prognosis of m-NSCLC has led to investigation of ICIs combined with other treatments with the intention of modulating the TME and sensitizing tumours to the effects of ICIs. Stereotactic ablative radiotherapy (SABR) in combination with ICIs is an area of intense interest. SABR is thought to evoke a pro-immunogenic response in the TME, with the capacity to turn a “cold”, unresponsive tumour to “hot” and receptive to ICI. In addition to improved local response, SABR is postulated to produce a heightened systemic immune response when compared to conventional radiotherapy (RT). Preclinical studies have demonstrated a synergistic effect of SABR + ICIs, and clinical studies in m-NSCLC showed safety and promising efficacy compared to systemic therapies alone. To optimize ICI + SABR, ICI choice, combinations, dosing and length of treatment, as well as sequencing of ICI + SABR all require further investigation. Appropriate sequencing may depend on the ICI(s) being utilized, with differing sites of metastases possibly eliciting differing immune responses. Single versus multisite radiation is controversial, whilst effects of irradiated tumour volume and nodal irradiation are increasingly recognized. Taken together, there is strong preclinical and biological rationale, with emerging clinical evidence, supporting the strategy of combining SABR + ICIs in m-NSCLC.

Role of modern radiotherapy in managing patients with hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer. Several treatment options are available for managing HCC patients, classified roughly as local, local-regional, and systemic therapies. The high post-monotherapy recurrence rate of HCC urges the need for the use of combined modalities to increase tumor control and patient survival. Different international guidelines offer treatment recommendations based on different points of view and classification systems. Radiotherapy (RT) is a well-known local-regional treatment modality for managing many types of cancers, including HCC. However, only some of these treatment guidelines include RT, and the role of combined modalities is rarely mentioned. Hence, the present study reviewed clinical evidence for the use of different combined modalities in managing HCC, focusing on modern RT's role. Modern RT has an increased utility in managing HCC patients, mainly due to two driving forces. First, technological advancement (e.g., stereotactic body radiotherapy and advanced proton-beam therapy) enables precise delivery of radiation to increase tumor control and reduce side effects in the surrounding normal tissue. Second, the boom in developing target therapies and checkpoint-blockade immunotherapy prolongs overall survival in HCC patients, re-emphasizing the importance of local tumor control. Remarkably, RT combines with systemic therapies to generate the systemic therapy augmented by radiotherapy effect, a benefit now being actively investigated.

Modified Glasgow Prognostic Score is predictive of prognosis for non-small cell lung cancer patients treated with stereotactic body radiation therapy: a retrospective study

We aimed to assess the predictive value of the modified Glasgow prognostic score (mGPS) in patients with non-small cell lung cancer (NSCLC) who underwent stereotactic body radiation therapy (SBRT). We retrospectively reviewed the records of 207 patients, with a median age of 79 years. The pretreatment mGPS was calculated and categorized as high (mGPS = 1-2) or low (mGPS = 0). The median follow-up duration was 40.7 months. The five-year overall survival (OS), progression-free survival (PFS) and time to progression (TTP) rates were 44.3%, 36% and 54.4%, respectively. Multivariate analysis revealed that mGPS was independently predictive of OS (hazard ratio [HR] 1.67; 95% confidence interval 1.14-2.44: P = 0.009), PFS (HR 1.58; 1.10-2.28: P = 0.014) and TTP (HR 1.66; 1.03-2.68: P = 0.039). Patients who had high mGPS showed significantly worse OS (33.3 vs 64.5 months, P = 0.003) and worse PFS (23.8 vs 39 months, P = 0.008) than those who had low mGPS. The data showed a trend that patients with high mGPS suffered earlier progression compared to those with low mGPS (54.3 vs 88.1 months, P = 0.149). We confirmed that mGPS is independently predictive of prognosis in NSCLC patients treated with SBRT.

The utilization of immunotherapy with radiation therapy in lung cancer: a narrative review

Despite decreasing smoking rates, lung cancer remains the leading cause of death from cancer in the United States. Radiation therapy has been established as an effective locoregional therapy for both early stage and locally advanced disease and is known to stimulate local immune response. Past treatment paradigms have established the role of combining cytotoxic chemotherapy regimens and radiation therapy to help address the local and systemic nature of lung cancer. However, these regimens have limitations in their tolerability due to toxicity. Additionally, cytotoxic chemotherapy has limited efficacy in preventing systemic spread of lung cancer. Newer systemic agents such as immune checkpoint inhibitors have shown improved survival in metastatic and locally advanced lung cancer and have the advantage of more limited toxicity profiles compared to cytotoxic chemotherapy. Furthermore, improved overall response rates and systemic tumor responses have been observed with the combination of radiation therapy and immunotherapy, leading to numerous active clinical trials evaluating the combination of immune checkpoint inhibition with radiotherapy. This comprehensive review discusses the current clinical data and ongoing studies evaluating the combination of radiation therapy and immunotherapy in both non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC).

The NIPRO Study: An Observational, Retrospective, Multicenter Study on the Safety of the Radiotherapy and Immunotherapy Combination for Advanced-Stage NSCLC

INTRODUCTION

In this observational, retrospective, multicenter study, we aimed to assess the safety of the combination of local metastasis-directed radiotherapy (RT) and immunotherapy (IT) in a cohort of advanced non-small-cell lung cancer (aNSCLC) patients.

MATERIAL AND METHODS

We collected clinical data of aNSCLC patients who received concomitant RT and anti-PD-1/PD-L1 inhibitors in seven Italian centers from September 2015 to June 2019. Concomitant RT was defined as delivered ≤4 weeks before or after the first or last administration of immunotherapy, or within two consecutive cycles of ICI. All adverse events apparently related to RT and/or IT were graded according to the Common Terminology Criteria for Adverse Events, version 4.0, and reported in terms of incidence and severity as immune related or RT related, or combined.

RESULTS

We analyzed the clinical charts of 187 patients. Median follow-up time was 23 months, and median overall survival was 16.5 months (range, 3-162). Thirteen patients developed pure RT-related side effects, and 43 patients (23.9%) developed immune-related side effects. No additive toxic effects were observed. A case of grade 5 pulmonary toxicity was recorded as a possible consequence of a combined effect.

CONCLUSION

This analysis suggests that the combination of concomitant RT and anti-PD-1/PD-L1 agents is safe, and the two toxicity profiles are independent.

PD-1 restrains IL-17A production from γδ T cells to modulate acute radiation-induced lung injury

Background

Combining radiotherapy (RT) with programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) inhibitors has been shown to enhance anti-tumor effects in the treatment of non-small cell lung carcinoma (NSCLC). Pulmonary toxicity is a major adverse effect of thoracic RT in NSCLC patients, whether it is administered alone or in combination with PD-1/PD-L1 inhibitors. This study aimed to evaluate the potential pulmonary toxicity of RT combined with concurrent PD-1 inhibitor and to clarify the underlying mechanisms.

Methods

Radiation-induced lung injury (RILI) was induced in C57BL/6 mice by given 24 Gy in three fractions on consecutive days, with or without concurrent injection of anti-PD-1 antibody. On days 3, 7, 14, and 28 after the first exposure to irradiation, lung tissue and peripheral blood samples were collected from the mice. Histological injury was analyzed, and inflammatory cell infiltration and interleukin (IL)-17A production in the lung tissues were quantified.

Results

Mice that received irradiation with concurrent administration of anti-PD-1 antibody had the highest histological score for RILI. In the murine lung tissues, the levels of PD-1 and IL-17A expression were increased in γδ T cells but not in the other CD3⁺ T cells after irradiation. Concurrent blockade of PD-1 enhanced IL-17A production from γδ T cells in the lung tissues after irradiation. In the mice with acute RILI, concurrent administration of anti-PD-1 antibody exaggerated pulmonary inflammation, with significantly increased levels of neutrophilic infiltration and IL-17A detected in both the lung and blood.

Conclusions

PD-1 could restrain IL-17A production from γδ T cells to modulate acute RILI. The concurrent administration of anti-PD-1 antibody aggravates the severity of acute RILI. More attention should be paid to pulmonary toxicity in patients undergoing thoracic RT with concurrent anti-PD-1 immunotherapy.

Combination of Immune Checkpoint Inhibitors and Radiotherapy for Advanced Non-Small-Cell Lung Cancer and Prostate Cancer: A Meta-Analysis

Objectives

Immune checkpoint inhibitors (ICI) combined with radiotherapy (RT) have emerged as a breakthrough therapy in the treatment of various cancers. The combination has a strong rationale, but data on their efficacy and safety are still limited. Hence, we comprehensively searched the database and performed this study to elucidate the clinical manifestations of this combined strategy.

Methods

We performed a meta-analysis of randomized trials that compared ICI plus RT with placebo plus RT or ICI alone for the treatment of advanced nonsmall-cell lung cancer (NSCLC) and prostate cancer. The outcomes included overall survival (OS), progression-free survival (PFS), disease control rate (DCR), and treatment-related adverse events. A fixed-effects or random-effects model was adopted depending on between-study heterogeneity.

Results

Three trials involving 1584 patients were included. ICI plus RT was significantly associated with improvement of OS (hazard ratio [HR] = 0.81, 95% confidence interval [CI] = 0.70–0.94, P=0.004), PFS (HR = 0.64; 95% CI 0.56–0.72, P < 0.00001), and DCR (relative risk [RR] = 1.38; 95% CI 1.03–1.84, P=0.03). A significant predictor for PFS with the combination of ICI and RT was age, as a significant improvement in PFS (HR = 0.49; 95% CI 0.37–0.64, P < 0.00001) was observed in NSCLC patients aged under 65 years. In safety analyses, patients receiving ICI plus RT had a significantly higher incidence of dyspnea (RR = 2.43; 95% CI 1.16–5.08, P=0.02) and pneumonitis of grade 3 or higher (RR = 2.78; 95% CI 1.32–5.85, P=0.007).

Conclusion

The combination of ICI and RT was associated with improved OS, PFS, and DCR. Patients under 65 years will be the dominant beneficiaries. However, the incidence of dyspnea and pneumonia of grade 3 or higher also increased, which deserves our vigilance.

Radiotherapy and Immunotherapy Combinations for Lung Cancer

PURPOSE OF REVIEW

Positive results from recent immunotherapy trials of non-small cell lung cancer (NSCLC) have coincided with a greater appreciation for the impact of radiation therapy (RT) on tumor immunity. Here, we summarize key clinical findings and ongoing efforts to combine immunotherapy and RT for the treatment of NSCLC.

RECENT FINDINGS

The role of immunotherapy for NSCLC has expanded significantly following the pivotal approvals of nivolumab and pembrolizumab for metastatic NSCLC, maintenance durvalumab in unresectable stage III NSCLC, and atezolizumab for metastatic NSCLC. Several small early-phase trials have demonstrated the ability of RT to elicit clinically significant tumor immunity. These positive findings support current trial efforts combining RT with immunotherapy for NSCLC. Recently initiated trials of RT and immunotherapy hold significant promise in expanding the therapeutic options for NSCLC. Optimization of therapy will require careful patient selection to yield meaningful improvements in clinical outcomes.

MR-guided stereotactic body radiation therapy for intracardiac and pericardial metastases

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Radiation is not typical in the standard of care for cardiac metastases.

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MR-guided radiation uses real-time imaging and offers better soft tissue contrast.

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Real-time MR-guidance allows for safe high dose radiation to cardiac metastases.

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MR-guided stereotactic radiation can improve symptoms without acute toxicity.

Aims

To assess the safety and efficacy of MR-guided stereotactic body radiation therapy (MRgSBRT) for cardiac metastases.

Materials/methods

This single institution retrospective analysis evaluated our experience with MRgSBRT for cardiac metastases. Response rate was compared between pre-RT and post-RT imaging. Symptomatic changes were also tracked and documented.

Results

Between 4/2019 and 3/2020, five patients with cardiac metastases (4 intracardiac and 1 pericardial) were treated with MRgSBRT. Median age at treatment was 73 years (range 64–80) and two patients had pre-existing cardiac disease. Histologies included melanoma and breast adenocarcinoma. Median lesion diameter was 2 cm (range 1.96–5.8 cm). Three patients were symptomatic, one of whom had pulmonary hypertension and RV enlargement. Another patient had an asymptomatic arrythmia. Median PTV prescribed dose was 40 Gy (range 40–50 Gy) and delivered in five fractions on nonconsecutive days. Median PTV volume was 53.4 cc (range 8.7–116.6 cc) and median coverage was 95% (range 84.1–100%). A uniform 3 mm margin was used for real-time gating, allowing a median 7% (range 5–10%) pixel excursion tolerance. Median follow-up was 4.7 months (range 0.9–12.3). Two patients exhibited stable disease, two had a partial response and one exhibited a complete response. All symptomatic patients experienced some relief. There were no acute adverse events, however, one patient without prior cardiac disease developed atrial fibrillation 6 months after treatment. Two patients died of causes unrelated to cardiac MRgSBRT.

Conclusion

In this largest known series of cardiac metastasis MRgSBRT, real-time image guidance enables safe treatment resulting in good response with improving presenting symptoms without acute adverse events.

Radiation-induced lung toxicity - cellular and molecular mechanisms of pathogenesis, management, and literature review

Lung, breast, and esophageal cancer represent three common malignancies with high incidence and mortality worldwide. The management of these tumors critically relies on radiotherapy as a major part of multi-modality care, and treatment-related toxicities, such as radiation-induced pneumonitis and/or lung fibrosis, are important dose limiting factors with direct impact on patient outcomes and quality of life. In this review, we summarize the current understanding of radiation-induced pneumonitis and pulmonary fibrosis, present predictive factors as well as recent diagnostic and therapeutic advances. Novel candidates for molecularly targeted approaches to prevent and/or treat radiation-induced pneumonitis and pulmonary fibrosis are discussed.

SBRT combined with PD-1/PD-L1 inhibitors in NSCLC treatment: a focus on the mechanisms, advances, and future challenges

Immune checkpoint inhibitors targeting programmed cell death 1 (PD-1), programmed cell death ligand-1 (PD-L1), and others have shown potent clinical efficacy and have revolutionized the treatment protocols of a broad spectrum of tumor types, especially non–small-cell lung cancer (NSCLC). Despite the substantial optimism of treatment with PD-1/PD-L1 inhibitors, there is still a large proportion of patients with advanced NSCLC who are resistant to the inhibitors. Preclinical and clinical trials have demonstrated that radiotherapy can induce a systemic antitumor immune response and have a great potential to sensitize refractory “cold” tumors to immunotherapy. Stereotactic body radiation therapy (SBRT), as a novel radiotherapy modality that delivers higher doses to smaller target lesions, has shown favorable antitumor effects with significantly improved local and distant control as well as better survival benefits in various solid tumors. Notably, research has revealed that SBRT is superior to conventional radiotherapy, possibly because of its more powerful immune activation effects. Thus, PD-1/PD-L1 inhibitors combined with SBRT instead of conventional radiotherapy might be more promising to fight against NSCLC, further achieving more favorable survival outcomes. In this review, we focus on the underlying mechanisms and recent advances of SBRT combined with PD-1/PD-L1 inhibitors with an emphasis on some future challenges and directions that warrant further investigation.