Immune checkpoint inhibition in patients treated with stereotactic radiation for brain metastases

The effects of immune checkpoint inhibitors vs. chemotherapy combined with brain radiotherapy in non-small cell lung cancer patients with brain metastases

BACKGROUND

Non-small cell lung cancer (NSCLC) is a prevalent form of cancer, often leading to brain metastases (BM) and a significant decline in patient prognosis. Whether immune checkpoint inhibitors (ICIs) combined with brain radiotherapy is superior to conventional chemotherapy combined with brain radiotherapy in those patients remains to be explored.

MATERIALS AND METHODS

Our study enrolled 161 NSCLC patients with BM who underwent either ICIs combined with brain radiotherapy or chemotherapy combined with brain radiotherapy. End points included overall survival (OS), progression-free survival (PFS), intracranial PFS (IPFS), and extracranial PFS (EPFS). Univariate and multivariate Cox regressions were employed to identify prognostic risk variables.

RESULTS

Patients receiving ICIs combined with brain radiotherapy exhibited significantly longer OS compared to those receiving chemotherapy combined with brain radiotherapy (34.80 months vs. 17.17 months, P = 0.005). In the Cox regression analysis, chemotherapy combined with brain radiotherapy (HR, 1.82; 95% CI, 1.09-3.05; P = 0.023), smoking (HR, 1.75; 95% CI, 1.02-2.99; P = 0.043) and squamous cell carcinoma (HR, 2.59; 95% CI, 1.31-5.13; P = 0.006) were associated with a worse prognosis. After propensity score matching (PSM), this finding remained consistent with before PSM (43.73 months vs. 17.17 months, P = 0.018). Squamous cell carcinoma (HR, 2.46; 95% CI, 1.15-5.26; P = 0.021) and CT + RT (HR, 2.11; 95% CI, 1.15-3.88; P = 0.016) were associated with a less favorable prognosis.

CONCLUSION

The study suggests that the combination of ICIs and brain radiotherapy provides superior OS for NSCLC patients with BM, compared to the chemotherapy combined with brain radiotherapy.

The Emerging Role of Immune Checkpoint Blockade for the Treatment of Lung Cancer Brain Metastases

Lung cancer has the highest incidence of brain metastases (BM) among solid organ cancers. Traditionally whole brain radiation therapy has been utilized for non-small-cell lung cancer (NSCLC) BM treatment, although stereotactic radiosurgery has emerged as the superior treatment modality for most patients. Highly penetrant central nervous system (CNS) tyrosine kinase inhibitors have also shown significant CNS activity in patients harboring select oncogenic drivers. There is emerging evidence that patients without oncogene-driven tumors derive benefit from the use of immune checkpoint inhibitors (ICIs). The CNS activity of ICIs have not been well studied given exclusion of patients with active BM from landmark trials, due to concerns of inadequate CNS penetration and activity. However, studies have challenged the idea of an immune-privileged CNS, given the presence of functional lymphatic drainage within the CNS and destruction of the blood brain barrier by BM. An emerging understanding of the interactions between tumor and CNS immune cells in the BM tumor microenvironment also support a role for immunotherapy in BM treatment. In addition, posthoc analyses of major trials have shown improved intracranial response and survival benefit of regimens with ICIs over chemotherapy (CT) alone for patients with BM. Two prospective phase 2 trials evaluating pembrolizumab monotherapy and atezolizumab plus CT in patients with untreated NSCLC BM also demonstrated significant intracranial responses. This review describes the interplay between CNS immune cells and tumor cells, discusses current evidence for ICI CNS activity from retrospective and prospective studies, and speculates on future directions of investigation.

Tumoral Interferon Beta Induces an Immune-Stimulatory Phenotype in Tumor-Associated Macrophages in Melanoma Brain Metastases

Type I interferons (IFN) are immune-stimulatory cytokines involved in antiviral and antitumor immune responses. They enhance the efficacy of immunogenic anticancer therapies such as radiotherapy by activating both innate and adaptive immune cells. Macrophages are one of the most abundant innate immune cells in the immune microenvironment of melanoma brain metastases (MBM) and can exert potent immune-suppressive functions. Here, we investigate the potential of tumoral type I IFNs to repolarize tumor-associated macrophages (TAM) in two murine MBM models and assess the effects of radiotherapy-induced type I IFN on TAMs in a transcriptomic MBM patient dataset. In mice, we describe a proinflammatory M1-like TAM phenotype induced by tumoral IFNβ and identify a myeloid type I IFN-response signature associated with a high M1/M2-like TAM ratio. Following irradiation, patients with MBM displaying a myeloid type I IFN-response signature showed increased overall survival, providing evidence that tumoral IFNβ supports an effective antitumor immune response by re-educating immune-regulatory TAM. These findings uncover type I IFN-inducing therapies as a potential macrophage-targeting therapeutic approach and provide a rationale for combining radiotherapy with concomitant immunotherapy to improve treatment response in patients with MBM.

SIGNIFICANCE

Our study shows that re-education of tumor-associated macrophages by tumoral IFNβ translates into improved clinical outcome in patients with melanoma brain metastases, providing pathomechanistic insights into synergistic type I interferon-inducing therapies with immunotherapies and warranting investigation of IFNβ as a predictive biomarker for combined radioimmunotherapy.

Real-world evaluation of first-line treatment of extensive-stage small-cell lung cancer with atezolizumab plus platinum/etoposide: a focus on patients with brain metastasis

PURPOSE

A previous real-world study conducted in China confirmed that first-line atezolizumab, in combination with etoposide/platinum (EP), leads to significantly longer progression-free survival (PFS) compared to EP alone in patients with extensive-stage small-cell lung cancer (ES-SCLC). The present study aimed to provide updated survival outcome data and evaluate the clinical efficacy of atezolizumab plus chemotherapy in ES-SCLC patients with brain metastasis (BM).

METHODS

This retrospective study included 225 patients with ES-SCLC who were treated with EP alone (EP group) or a combination of EP + atezolizumab (atezolizumab group). Survival outcomes for the total study sample and patients in the BM subgroup were estimated using the Kaplan-Meier method.

RESULTS

The atezolizumab group continued to demonstrate significantly longer PFS than the EP group (hazard ratio [HR], 0.68). The median overall survival (OS) was 26.2 months in the atezolizumab group vs. 14.8 months in the EP group (HR, 0.63). Additionally, among the BM patients in our study, the median PFS was found to be longer in the atezolizumab group (7.0 months) than in the EP group (4.1 months) (HR, 0.46). The OS of the BM patients did not differ significantly between the two treatment groups.

CONCLUSIONS

The addition of atezolizumab to EP as a first-line treatment for ES-SCLC was found to improve survival outcomes. This treatment combination may also prolong PFS in patients with BM, regardless of the administration of cranial irradiation. However, among the BM patients in our study, there was no significant difference in OS between the two treatment groups.

Fractionated stereotactic radiotherapy of intracranial postoperative cavities after resection of brain metastases - Clinical outcome and prognostic factors

Background and Purpose

After surgical resection of brain metastases (BM), radiotherapy (RT) is indicated. Postoperative stereotactic radiosurgery (SRS) reduces the risk of local progression and neurocognitive decline compared to whole brain radiotherapy (WBRT). Aside from the optimal dose and fractionation, little is known about the combination of systemic therapy and postoperative fractionated stereotactic radiotherapy (fSRT), especially regarding tumour control and toxicity.

Methods

In this study, 105 patients receiving postoperative fSRT with 35 Gy in 7 fractions performed with Cyberknife were retrospectively reviewed. Overall survival (OS), local control (LC) and total intracranial brain control (TIBC) were analysed via Kaplan-Meier method. Cox proportional hazards models were used to identify prognostic factors.

Results

Median follow-up was 20.8 months. One-year TIBC was 61.6% and one-year LC was 98.6%. Median OS was 28.7 (95%-CI: 16.9-40.5) months. In total, local progression (median time not reached) occurred in 2.0% and in 20.4% radiation-induced contrast enhancements (RICE) of the cavity (after median of 14.3 months) were diagnosed. Absence of extracranial metastases was identified as an independent prognostic factor for superior OS (p = <0.001) in multivariate analyses, while a higher Karnofsky performance score (KPS) was predictive for longer OS in univariate analysis (p = 0.041). Leptomeningeal disease (LMD) developed in 13% of patients.

Conclusion

FSRT after surgical resection of BM is an effective and safe treatment approach with excellent local control and acceptable toxicity. Further prospective randomized trials are needed to establish standardized therapeutic guidelines.

Symptomatic brain metastases in melanoma

Although clinical outcomes in metastatic melanoma have improved in recent years, the morbidity and mortality of symptomatic brain metastases remain challenging. Response rates and survival outcomes of patients with symptomatic melanoma brain metastases (MBM) are significantly inferior to patients with asymptomatic disease. This review focusses upon the specific challenges associated with the management of symptomatic MBM, discussing current treatment paradigms, obstacles to improving clinical outcomes and directions for future research.

Progress of immune checkpoint inhibitors therapy for non-small cell lung cancer with liver metastases

Nearly one-fifth of patients with non-small cell Lung Cancer (NSCLC) will develop liver metastases (LMs), and the overall treatment strategy of LMs will directly affect the survival of patients. However, some retrospective studies have found that patients receiving chemotherapy or targeted therapy have a poorer prognosis once LMs develop. In recent years, multiple randomised controlled trials (RCTS) have shown significant improvements in outcomes for patients with advanced lung cancer following the introduction of immune checkpoint inhibitors (ICIs) compared to conventional chemotherapy. ICIs is safe and effective in patients with LMs, although patients with LMs are mostly underrepresented in randomised clinical trials. However, NSCLC patients with LMs have a significantly worse prognosis than those without LMs when treated with ICIs, and the mechanism by which LMs induce systemic anti-tumour immunity reduction is unknown, so the management of LMs in patients with NSCLC is a clinical challenge that requires more optimised therapies to achieve effective disease control. In this review, we summarised the mechanism of ICIs in the treatment of LMs, the clinical research and treatment progress of ICIs and their combination with other therapies in patients with LMs from NSCLC.

The Safety and Efficacy of Concurrent Immune Checkpoint Blockade and Stereotactic Radiosurgery Therapy with Practitioner and Researcher Recommendations

BACKGROUND

Immune checkpoint inhibitors (ICIs) have shown growing promise in the treatment of brain metastases, especially combined with stereotactic radiosurgery (SRS). The combination of ICIs with SRS has been studied for efficacy as well as increasing radiation necrosis risks. In this review, we compare clinical outcomes of radiation necrosis, intracranial control, and overall survival between patients with brain metastases treated with either SRS alone or SRS-ICI combination therapy.

METHODS

A literature search of PubMed, Scopus, Embase, Web of Science, and Cochrane was performed in May 2023 for articles comparing the safety and efficacy of SRS/ICI versus SRS-alone for treating brain metastases.

RESULTS

The search criteria identified 1961 articles, of which 48 met inclusion criteria. Combination therapy with SRS and ICI does not lead to significant increases in incidence of radiation necrosis either radiographically or symptomatically. Overall, no difference was found in intracranial control between SRS-alone and SRS-ICI combination therapy. Combination therapy is associated with increased median overall survival. Notably, some comparative studies observed decreased neurologic deaths, challenging presumptions that improved survival is due to greater systemic control. The literature supports SRS-ICI administration within 4 weeks of another for survival but remains inconclusive, requiring further study for other outcome measures.

CONCLUSIONS

Combination SRS-ICI therapy is associated with significant overall survival benefit for patients with brain metastases without significantly increasing radiation necrosis risks compared to SRS alone. Although intracranial control rates appear to be similar between the 2 groups, timing of treatment delivery may improve control rates and demands further study attention.

The Impact of Immune Checkpoint Inhibition on the Risk of Radiation Necrosis Following Stereotactic Radiotherapy for Metastatic Brain Cancer

Purpose/objective Forty percent of cancer patients develop brain metastases (BM) and are often treated with stereotactic radiation (SRS/SRT). Checkpoint inhibitor (CI) use is suspected of increasing the risk of radiation necrosis (RN). Our aim is to determine whether treatment with CI is associated with an increased risk of RN in BM patients treated with SRS/SRT. Methods We retrospectively identified the medical records of BM patients treated with SRS/SRT between 1/2017 and 12/2021 using an institutional database. RN was defined by MRI imaging read by neuroradiologists and/or surgical pathology. V12GY of patients with and without RN was compared using the Mann-Whitney test. The chi-square test was used to see if RN was associated with CI use, histology, particular CI agent used, > 1 course SRS/SRT, SRS/SRT dose, chemotherapy, whole brain radiotherapy (WBRT), age, or sex. Results Two hundred and fifty-nine patients treated with 455 courses of SRS/SRT were analyzed. The most common primary histologies were lung 56% (N=146), breast 14% (N= 37), melanoma 9% (N=24), and renal cancer 7% (N=18). A total of 53.8% (N = no. of patients) were treated with CI. The overall rate of any RN was 21.8% (N=27) in the CI group compared to 14.8% (N=141) in the non-CI group (p=0.174). Mean V12Gy was 15.525 cc and 9.419 cc in patients with and without RN (p=0.02768). Mean number of SRS/SRT courses was 2 and 1.53 for patients with and without RN, and >1 course of SRS/SRT was a predictor of RN (p <0.01). Other features analyzed were not significant. Conclusion RN was higher in the BM patients treated with SRS/SRT receiving CI compared to non-CI patients (21.8%, N=27, versus 14.6%, N= 16), but failed to reach statistical significance. V12Gy and > 1 course of SRS/SRT was associated with RN. Caution should be taken in treating patients with SRS/SRT and CI there might be an increased risk of RN.

Progress of immune checkpoint inhibitors therapy for non-small cell lung cancer with brain metastases

About 40% of patients with non-small cell lung cancer (NSCLC) develop brain metastases (BMs) throughout the disease, and the occurrence of BMs is considered to have a fairly high mortality rate. Therefore, the management of brain metastases in NSCLC patients is a clinical challenge. Currently, multidisciplinary diagnosis and treatment methods are often used to achieve effective control of intracranial disease and prolong survival. Immunotherapy (IT) is one of the core therapies for NSCLC. Single or combined IT represented by immune checkpoint inhibitors(ICIs) of programmed death-1(PD-1)/ programmed cell death-ligand 1 (PD-L1) can significantly improve the prognosis of patients with advanced NSCLC.ICIs has been shown to be safe and effective in patients with BMs, although patients with BMs are mostly underrepresented in randomized clinical trials. In this review, we summarized the mechanism of ICIs in the treatment of BMs, and the clinical research and treatment progress of ICIs and their combination with other therapies in patients with BMs s from NSCLC.

Optimizing the synergy between stereotactic radiosurgery and immunotherapy for brain metastases

Solid tumors metastasizing to the brain are a frequent occurrence with an estimated incidence of approximately 30% of all cases. The longstanding conventional standard of care comprises surgical resection and whole-brain radiotherapy (WBRT); however, this approach is associated with limited long-term survival and local control outcomes. Consequently, stereotactic radiosurgery (SRS) has emerged as a potential alternative approach. The primary aim of SRS has been to improve long-term control rates. Nevertheless, rare observations of abscopal or out-of-field effects have sparked interest in the potential to elicit antitumor immunity via the administration of high-dose radiation. The blood-brain barrier (BBB) has traditionally posed a significant challenge to the efficacy of systemic therapy in managing intracranial metastasis. However, recent insights into the immune-brain interface and the development of immunotherapeutic agents have shown promise in preclinical and early-phase clinical trials. Researchers have investigated combining immunotherapy with SRS to enhance treatment outcomes in patients with brain metastasis. The combination approach aims to optimize long-term control and overall survival (OS) outcomes by leveraging the synergistic effects of both therapies. Initial findings have been encouraging in the management of various intracranial metastases, while further studies are required to determine the optimal order of administration, radiation doses, and fractionation regimens that have the potential for the best tumor response. Currently, several clinical trials are underway to assess the safety and efficacy of administering immunotherapeutic agents concurrently or consecutively with SRS. In this review, we conduct a comprehensive analysis of the advantages and drawbacks of integrating immunotherapy into conventional SRS protocols for the treatment of intracranial metastasis.

Effectiveness of immune checkpoint inhibitors in combination with stereotactic radiosurgery for patients with brain metastases from renal cell carcinoma: inverse probability of treatment weighting using propensity scores

OBJECTIVE

Stereotactic radiosurgery (SRS) is the mainstay for treating brain metastases (BMs) from renal cell carcinoma (RCC). In recent years, immune checkpoint inhibitors (ICIs) have been applied to metastatic RCC and have contributed to improved outcomes. The authors investigated whether SRS with concurrent ICIs for RCC BM prolongs overall survival (OS) and improves intracranial disease control and whether there are any safety concerns.

METHODS

Patients who underwent SRS for RCC BMs at the authors' institution between January 2010 and January 2021 were included. Concurrent use of ICIs was defined as no more than 3 months between SRS and ICI administration. The time-to-event analysis of OS and intracranial progression-free survival (IC-PFS) between the groups with and without ICIs (ICI+SRS and SRS, respectively) was performed using inverse probability of treatment weighting (IPTW) based on propensity scores (PSs) to control for selection bias. Four baseline covariates (Karnofsky Performance Scale score, extracranial metastases, hemoglobin, and number of BMs) were selected to calculate PSs.

RESULTS

In total, 57 patients with 147 RCC BMs were eligible. The median OS for all patients was 9.1 months (95% CI 6.0-18.9 months), and the median IC-PFS was 4.4 months (95% CI 3.1-6.8 months). Twelve patients (21%) received concurrent ICIs. The IPTW-adjusted 1-year OS rates in the ICI+SRS and SRS groups were 66% and 38%, respectively (HR 0.30, 95% C 0.13-0.69; p = 0.005), and the IPTW-adjusted 1-year IC-PFS rates were 52% and 16%, respectively (HR 0.30, 95% CI 0.14-0.62; p = 0.001). Severe tumor hemorrhage (Common Terminology Criteria for Adverse Events [CTCAE] grade 4 or 5) occurred immediately after SRS in 2 patients in the SRS group. CTCAE grade 2 or 3 toxicity was observed in 2 patients in the ICI+SRS group and 5 patients in the SRS group.

CONCLUSIONS

Although the patient number was small and the analysis preliminary, the present study found that SRS with concurrent ICIs for RCC BM patients prolonged survival and provided durable intracranial disease control, with no apparent increase in treatment-related adverse events.

Novel Mechanisms and Future Opportunities for the Management of Radiation Necrosis in Patients Treated for Brain Metastases in the Era of Immunotherapy

Radiation necrosis, also known as treatment-induced necrosis, has emerged as an important adverse effect following stereotactic radiotherapy (SRS) for brain metastases. The improved survival of patients with brain metastases and increased use of combined systemic therapy and SRS have contributed to a growing incidence of necrosis. The cyclic GMP-AMP (cGAMP) synthase (cGAS) and stimulator of interferon genes (STING) pathway (cGAS-STING) represents a key biological mechanism linking radiation-induced DNA damage to pro-inflammatory effects and innate immunity. By recognizing cytosolic double-stranded DNA, cGAS induces a signaling cascade that results in the upregulation of type 1 interferons and dendritic cell activation. This pathway could play a key role in the pathogenesis of necrosis and provides attractive targets for therapeutic development. Immunotherapy and other novel systemic agents may potentiate activation of cGAS-STING signaling following radiotherapy and increase necrosis risk. Advancements in dosimetric strategies, novel imaging modalities, artificial intelligence, and circulating biomarkers could improve the management of necrosis. This review provides new insights into the pathophysiology of necrosis and synthesizes our current understanding regarding the diagnosis, risk factors, and management options of necrosis while highlighting novel avenues for discovery.

How many brain metastases can be treated with stereotactic radiosurgery before the radiation dose delivered to normal brain tissue rivals that associated with standard whole brain radiotherapy?

INTRODUCTION

Clinical trial data comparing outcomes after administration of stereotactic radiosurgery (SRS) or whole-brain radiotherapy (WBRT) to patients with brain metastases (BM) suggest that SRS better preserves cognitive function and quality of life without negatively impacting overall survival. Here, we estimate the maximum number of BM that can be treated using single and multi-session SRS while limiting the dose of radiation delivered to normal brain tissue to that associated with WBRT.

METHODS

Multiple-tumor SRS was simulated using a Monte Carlo - type approach and a pre-calculated dose kernel method. Tumors with diameters ≤36 mm were randomly placed throughout the contoured brain parenchyma until the brain mean dose reached 3 Gy, equivalent to the radiation dose delivered during a single fraction of a standard course of WBRT (a total dose of 30 Gy in 10 daily fractions of 3 Gy). Distribution of tumor sizes, dose coverage, selectivity, normalization, and maximum dose data used in the simulations were based on institutional clinical metastases data.

RESULTS

The mean number of tumors treated, mean volume of healthy brain tissue receiving > 12 Gy (V12) per tumor, and total tumor volume treated using mixed tumor size distributions were 12.7 ± 4.2, 2.2 cc, and 12.9 cc, respectively. Thus, we estimate that treating 12-13 tumors per day over 10 days would deliver the dose of radiation to healthy brain tissue typically associated with a standard course of WBRT.

CONCLUSION

Although in clinical practice, treatment with SRS is often limited to patients with ≤15 BM, our findings suggest that many more lesions could be targeted while still minimizing the negative impacts on quality of life and neurocognition often associated with WBRT. Results from this in silico analysis require clinical validation.

[Efficacy and Safety of Radiotherapy Combined with Immunotherapy for Brain Metastases from Lung Cancer: A Meta-analysis]

BACKGROUND

Immunotherapy (IT) is recommended for the treatment of advanced non-small cell lung cancer (NSCLC), while brain radiotherapy (RT) is the mainstream treatment for patients with brain metastases (BM). This study aimed to investigate the efficacy and safety of combined use of RT and IT.

METHODS

The date was limited to May 1, 2022, and literature searches were carried out in CNKI, Wanfang, PubMed, EMBASE and Cochrane databases. Heterogeneity was judged using the I2 test and P value. Publication bias was assessed using a funnel plot. The quality of included studies was assessed using the Newcastle-Ottawa Scale (NOS). Statistical analysis was performed using Stata 16.0 software.

RESULTS

A total of 17 articles involving 2,636 patients were included. In the comparison of RT+IT group and RT group, no significant difference was found in overall survival (OS) (HR=0.85, 95%CI: 0.52-1.38, I2=73.9%, Pheterogeneity=0.001) and intracranial distance control (DBC) (HR=1.04, 95%CI: 0.55-1.05, I2=80.5%, Pheterogeneity<0.001), but the intracranial control (LC) in the RT+IT group was better than the RT group (HR=0.46, 95%CI: 0.22-0.94, I2=22.2%, Pheterogeneity=0.276), and the risk of radiation necrosis/treatment-related imaging changes (RN/TRIC) was higher than RT (HR=1.72, 95%CI: 1.12-2.65, I2=40.2%, Pheterogeneity=0.153). In the comparison between the RT+IT concurrent group and the sequential group, no significant difference was found in OS (HR=0.62, 95%CI: 0.27-1.43, I2=74.7%, Pheterogeneity=0.003) and RN/TRIC (HR=1.72, 95%CI: 0.85-3.47, I2=0%, Pheterogeneity=0.388) was different between the two groups. However, DBC in the concurrent treatment group was better than that in the sequential treatment group (HR=0.77, 95%CI: 0.62-0.96, I2=80.5%, Pheterogeneity<0.001).

CONCLUSIONS

RT combined with IT does not improve the OS of NSCLC patients with BM, but also increases the risk of RN/TRIC. In addition, compared with sequential RT and IT, concurrent RT and IT improved the efficacy of DBC.

DEGRO practical guideline for central nervous system radiation necrosis part 1: classification and a multistep approach for diagnosis

PURPOSE

The Working Group for Neuro-Oncology of the German Society for Radiation Oncology in cooperation with members of the Neuro-Oncology Working Group of the German Cancer Society aimed to define a practical guideline for the diagnosis and treatment of radiation-induced necrosis (RN) of the central nervous system (CNS).

METHODS

Panel members of the DEGRO working group invited experts, participated in a series of conferences, supplemented their clinical experience, performed a literature review, and formulated recommendations for medical treatment of RN including bevacizumab in clinical routine.

CONCLUSION

Diagnosis and treatment of RN requires multidisciplinary structures of care and defined processes. Diagnosis has to be made on an interdisciplinary level with the joint knowledge of a neuroradiologist, radiation oncologist, neurosurgeon, neuropathologist, and neuro-oncologist. A multistep approach as an opportunity to review as many characteristics as possible to improve diagnostic confidence is recommended. Additional information about radiotherapy (RT) techniques is crucial for the diagnosis of RN. Misdiagnosis of untreated and progressive RN can lead to severe neurological deficits. In this practice guideline, we propose a detailed nomenclature of treatment-related changes and a multistep approach for their diagnosis.

Gamma knife icon based hypofractionated stereotactic radiosurgery (GKI-HSRS) for brain metastases: impact of dose and volume

OBJECTIVE

Gamma Knife Icon-based hypofractionated stereotactic radiosurgery (GKI-HSRS) is a novel technical paradigm in the treatment of brain metastases that allows for both the dosimetric benefits of the GKI stereotactic radiosurgery (SRS) platform as well as the biologic benefits of fractionation. We report mature local control and adverse radiation effect (ARE) outcomes following 5 fraction GKI-HSRS for intact brain metastases.

METHODS

Patients with intact brain metastases treated with 5-fraction GKI-HSRS were retrospectively reviewed. Survival, local control, and adverse radiation effect rates were determined. Univariable and multivariable regression (MVA) were performed on potential predictive factors.

RESULTS

Two hundred and ninety-nine metastases in 146 patients were identified. The median clinical follow-up was 10.7 months (range 0.5-47.6). The median total dose and prescription isodose was 27.5 Gy (range, 20-27.5) in 5 daily fractions and 52% (range, 45-93), respectively. The median overall survival (OS) was 12.7 months, and the 1-year local failure rate was 15.2%. MVA identified a total dose of 27.5 Gy vs. ≤ 25 Gy (hazard ratio [HR] 0.59, p = 0.042), and prior chemotherapy exposure (HR 1.99, p = 0.015), as significant predictors of LC. The 1-year ARE rate was 10.8% and the symptomatic ARE rate was 1.8%. MVA identified a gross tumor volume of ≥ 4.5 cc (HR 7.29, p < 0.001) as a significant predictor of symptomatic ARE.

CONCLUSION

Moderate total doses in 5 daily fractions of GKI-HSRS were associated with high rates of LC and a low incidence of symptomatic ARE.

Local and distant brain control in melanoma and NSCLC brain metastases with concurrent radiosurgery and immune checkpoint inhibition

INTRODUCTION

The treatment of brain metastases with stereotactic radiosurgery (SRS) in combination with immune checkpoint inhibitors (ICI) has become more common in recent years, but there is a lack of prospective data on cancer control outcomes when these therapies are administered concurrently.

METHODS

Data were retrospectively reviewed for patients with non-small cell lung cancer (NSCLC) and melanoma brain metastases treated with SRS at a single institution from May 2008 to January 2017. A parametric proportional hazard model is used to detect the effect of concurrent ICI within 30, 60, or 90 days of ICI administration on local control and distant in-brain control. Other patient and lesion characteristics are treated as covariates and adjusted in the regression. A frailty term is added in the baseline hazard to capture the within-patient correlation.

RESULTS

We identified 144 patients with 477 total lesions, including 95 NSCLC patients (66.0%), and 49 (34.0%) melanoma patients. On multivariate analysis, concurrent SRS and ICI (SRS within 30 days of ICI administration) was not associated with local control but was associated with distant brain control. When controlling for prior treatment to lesion, number of lesions, and presence of extracranial metastases, patients receiving this combination had a statistically significant decrease in distant brain failure compared to patients that received non-concurrent ICI or no ICI (HR 0.15; 95% CI 0.05-0.47, p = 0.0011).

CONCLUSION

Concurrent ICI can enhance the efficacy of SRS. Prospective studies would allow for stronger evidence to support the impact of concurrent SRS and ICI on disease outcomes.

Irradiation immunity interactions

The immune system can influence cancer development by both impeding and/or facilitating tumour growth and spread. A better understanding of this complex relationship is fundamental to optimise current and future cancer therapeutic strategies. Although typically regarded as a localised and immunosuppressive anti‐cancer treatment modality, radiation therapy has been associated with generating profound systemic effects beyond the intended target volume. These systemic effects are immune‐driven suggesting radiation therapy can enhance anti‐tumour immunosurveillance in some instances. In this review, we summarise how radiation therapy can positively and negatively affect local and systemic anti‐tumour immune responses, how co‐administration of immunotherapy with radiation therapy may help promote anti‐tumour immunity, and how the use of immune biomarkers may help steer radiation therapy‐immunotherapy personalisation to optimise clinical outcomes.

Defining unique clinical hallmarks for immune checkpoint inhibitor-based therapies

IntroductionImmuno-oncology therapies, including immune checkpoint inhibitors (ICIs), have transformed cancer care and have brought into question whether classic oncology efficacy assessments adequately describe the distinctive responses observed with these agents. With more ICI-based therapies being approved across multiple tumor types, it is essential to define unique clinical hallmarks of these agents and their associated assessments to better reflect the therapeutic impact for both patients and physicians. Long-term survival and objective responses, such as depth and durability of responses, treatment-free survival, efficacy in brain metastases, improved health-related quality of life, and unique safety profiles, are among the hallmarks that have emerged for ICI therapies. An established clinical hallmark is a sustained long-term survival, as evidenced by a delayed separation of Kaplan-Meier survival curves, and a plateau at ~3 years. Combination ICI therapies provide the opportunity to raise this plateau, thereby affording durable survival benefits to more patients. Deepening of responses over time is a unique clinical ICI hallmark, with patients responding long term and with more durable complete responses. Depth of response has demonstrated prognostic value for long-term survival in some cancers, and several ICI studies have shown sustained responses even after discontinuing ICI therapy, offering the potential for treatment-free intervals. Although clinical evidence supporting efficacy in brain metastases is limited, favorable ICI intracranial responses have been seen that are largely concordant with extracranial responses. While patient outcomes can be significantly improved with ICIs, they are associated with unique immune-mediated adverse reactions (IMARs), including delayed ICI toxicities, and may require multidisciplinary management for optimal care. Interestingly, patients discontinuing ICIs for IMARs may maintain responses similar to patients who did not discontinue for an IMAR, whether they restarted ICI therapy or not.ConclusionHerein, we comprehensively review and refine the clinical hallmarks uniquely associated with ICI therapies, which not only will rejuvenate our assessment of ICI therapeutic outcomes but also will lead to a greater appreciation of the effectiveness of ICI therapies.

Progress and prospects of flattening filter free beam technology in radiosurgery and stereotactic body radiotherapy

The aim of this work is to summarize and evaluate the current status of knowledge on flattening filter free (FFF) beams and their applications in stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT). A PubMed search was undertaken in order to identify relevant publications using FFF and stereotactic radiotherapy as keywords. On a clinical aspect, lung tumors treated with FFF SBRT show promising results in terms of local control and overall survival with acute toxicities consistent with those that occur with standard radiotherapy. Beside lung, SBRT is suitable for different anatomical sites such as liver, prostate, cervix, etc. offering similar results: reduced treatment time, good tumor control and mild acute toxicities. Regarding brain tumors, the employment of SRS with FFF beams significantly reduces treatment time and provides notable normal tissue sparing due to the sharp dose fall-off outside the tumor.

Immunotherapy in association with stereotactic radiotherapy for Non-Small Cell Lung Cancer brain metastases: results from a multicentric retrospective study on behalf of AIRO

BACKGROUND

To define efficacy and toxicity of Immunotherapy (IT) with stereotactic radiotherapy (SRT) including radiosurgery (RS) or hypofractionated SRT (HFSRT) for brain metastases (BM) from Non-Small Cell Lung Cancer (NSCLC) in a multicentric retrospective study from AIRO (Italian Association of Radiotherapy and Clinical Oncology).

METHODS

NSCLC patients with BM receiving SRT+IT and treated in 19 Italian centers were analysed and compared with a control group of patients treated with exclusive SRT.

RESULTS

One hundred patients treated with SRT+IT and 50 patients treated with SRT-alone were included. Patients receiving SRT+IT had a longer intracranial Local Progression Free Survival (iLPFS) (propensity score-adjusted p=0.007). Among patients who, at the diagnosis of BM, received IT and had also extracranial progression (n=24), IT administration after SRT was shown to be related to a better overall survival (OS) (p=0.037). At multivariate analysis, non-adenocarcinoma histology, KPS =70 and use of HFSRT were associated with a significantly worse survival (p=0.019, p=0.017 and p=0.007 respectively). Time interval between SRT and IT ≤7 days (n=90) was shown to be related to a longer OS if compared to SRT-IT interval >7 days (n=10) (propensity score-adjusted p=0.008). The combined treatment was well tolerated. No significant difference in terms of radionecrosis between SRT+IT patients and SRT-alone patients was observed. Time interval between SRT and IT had no impact on toxicity rate.

CONCLUSIONS

Combined SRT+IT was a safe approach, associated with a better iLPFS if compared to exclusive SRT.

Evaluation of practical experiences of German speaking radiation oncologists in combining radiation therapy with checkpoint blockade

The results of this survey reveal current clinical practice in the handling of combined radioimmunotherapy with Immune Checkpoint Inhibitors (RT + ICI). We aim to provide a basis to open a discussion for clinical application of RT + ICI by analyzation of experts’ assessment. We conducted a survey with 24 items with a focus on side effects of RT + ICI, common practice of scheduling and handling of adverse events. After pilot testing by radiation oncology experts the link to the online survey was sent to all members of the German Society of Radiation Oncology (DEGRO). In total, 51 radiation oncologists completed the questionnaire. Pulmonary toxicity under RT + ICI with ICIs was reported most frequently. Consensus was observed for bone and soft tissue RT of the limbs in favor for no interruption of ICIs. For cranial RT half of the participants do not suspend ICIs during normofractionated radiotherapy (nfRT) or stereotactic hypofractionated RT (SRT). More participants pause ICIs for central than for peripheral thoracic region. Maintenance therapy with ICIs is mostly not interrupted prior to RT. For management of RT associated pneumonitis under durvalumab the majority of 86.3% suggest corticosteroid therapy and 76.5% would postpone the next cycle of ICI therapy. The here obtained assessment and experiences by radiation oncologists reveal a large variability in practical handling of combined RT + ICI. Until scientific evidence is available a discussion for current clinical application of RT + ICI should be triggered. Interdisciplinary consensus guidelines with practical recommendations are required.

Poor performance status and brain metastases treatment: who may benefit from the stereotactic radiotherapy?

BACKGROUND

Poor Performance Status (PS) of cancer patients, defined as PS score 2-3, is an impediment for many drug- and irradiation-based treatments, supported by the trials that exclude subjects with PS < 1. Reports on the benefits of stereotactic radiotherapy (SRT) for brain metastases (BMs) in poor PS patients are scarce. We sought to review the characteristics and survival outcomes of this cohort, to assess who may benefit most from SRT.

METHODS

We retrospectively evaluated 73 patients with PS 2 or 3 (63 and 10 cases) treated with SRT for 150 BMs from 2012 to 2018. Patients' characteristics and post-SRT survival, stratified by concomitant systemic treatment (CST) were assessed using the Kaplan-Meier method (p-value < 0.05).

RESULTS

Non-small cell lung cancer was the most frequent primary tumor. Extracranial metastases were present in 86.3% of patients. The median overall survival (mOS) after SRT was estimated as 6.0 months (range 0.2-37.7), with 6- and 12-month survival rates of 51.0% and 21.0%, respectively. CST was administrated to 59.7% of patients (immunotherapy, target therapy or chemotherapy). Patients treated with CST presented larger mOS (6.7 vs. 4.4 months for patients treated with SRT alone, p = 0.3), and better 6- and 12-month survival rates (59% and 24% vs. 37% and 18% in patients not treated with CST).

CONCLUSIONS

Survival rate after SRT for BMs in poor performance patients, especially with PS 2, can justify SRT, in particular if an effective systemic treatment is available. Both SRT and CST should be more accessible for these patients in clinical practice.