Ipilmumab and cranial radiation in metastatic melanoma patients: a case series and review

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.

Opportunities and challenges in combining immunotherapy and radiotherapy in esophageal cancer

BACKGROUND

Immunotherapy has shown promise in the treatment of esophageal cancer, but using it alone only benefits a small number of patients. Most patients either do not have a significant response or develop secondary drug resistance. The combination of radiotherapy and immunotherapy appears to be a promising approach to treating esophageal cancer.

PURPOSE

We reviewed milestone clinical trials of radiotherapy combined with immunotherapy for esophageal cancer. We then discussed potential biomarkers for radiotherapy combined with immunotherapy, including programmed cell death-ligand 1 (PD-L1) status, tumor mutation burden (TMB), tumor-infiltrating lymphocytes, ct-DNA, imaging biomarkers, and clinical factors. Furthermore, we emphasize the key mechanisms of radiation therapy-induced immune stimulation and immune suppression in order to propose strategies for overcoming immune resistance in radiation therapy (RT). Lastly, we discussed the emerging role of low-dose radiotherapy (LDRT) , which has become a promising approach to overcome the limitations of high-dose radiotherapy.

CONCLUSION

Radiotherapy can be considered a triggering factor for systemic anti-tumor immune response and, with the assistance of immunotherapy, can serve as a systemic treatment option and potentially become the standard treatment for cancer patients.

Radiotherapy for extensive-stage small-cell lung cancer in the immunotherapy era

Currently, chemoimmunotherapy is the first-line treatment for extensive-stage small-cell lung cancer (ES-SCLC). However, only 0.8%-2.5% of the patients presented complete response after chemoimmunotherapy. Considering that ES-SCLC is highly sensitive to radiotherapy, the addition of radiotherapy after first-line treatment for ES-SCLC could further improve local control, which may be beneficial for patients' survival. Prior studies have shown that consolidative thoracic radiotherapy (cTRT) can decrease disease progression and improve overall survival in patients with ES-SCLC who respond well to chemotherapy. However, the efficacy and safety of cTRT in the immunotherapy era remain unclear owing to a lack of prospective studies. Prophylactic cranial irradiation (PCI) has been shown to decrease brain metastasis (BM) and prolong survival in patients with limited-stage SCLC in previous reports. However, according to current guidelines, PCI is not commonly recommended for ES-SCLC. Immunotherapy has the potential to reduce the incidence of BM. Whether PCI can be replaced with regular magnetic resonance imaging surveillance for ES-SCLC in the era of immunotherapy remains controversial. Whole brain radiation therapy (WBRT) is the standard treatment for BM in SCLC patients. Stereotactic radiosurgery (SRS) has shown promise in the treatment of limited BM. Considering the potential of immunotherapy to decrease BM, it is controversial whether SRS can replace WBRT for limited BM in the immunotherapy era. Additionally, with the addition of immunotherapy, the role of palliative radiotherapy may be weakened in patients with asymptomatic metastatic lesions. However, it is still indispensable and urgent for patients with obvious symptoms of metastatic disease, such as spinal cord compression, superior vena cava syndrome, lobar obstruction, and weight-bearing metastases, which may critically damage the quality of life and prognosis. To improve the outcome of ES-SCLC, we discuss the feasibility of radiotherapy, including cTRT, PCI, WBRT/SRS, and palliative radiotherapy with immunotherapy based on existing evidence, which may offer specific prospects for further randomized trials and clinical applications.

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.

Radiotherapy combined with immune checkpoint inhibitors in locally advanced/metastatic esophageal squamous cell carcinoma: clinical trials, efficacy and future directions

Esophageal squamous cell carcinoma (ESCC) is a common malignancy worldwide and often diagnosed at advanced stages with poor prognosis. Combination of radiotherapy and immunotherapy seems to be a promising approach for treating ESCC. This comprehensive review article summarizes the current state of combination of radiotherapy and immunotherapy in locally advanced/metastatic ESCC, delineates the clinical trials that merit attention, and outlines unresolved issues and future research directions in this field. The clinical trial findings suggest that radio-immunotherapy combination may improve tumor response and overall survival with manageable side effects, highlighting the importance of patient selection and the necessity for further research to optimize treatment strategies. Issues such as irradiation dosage, fractionation regimen, irradiation site and technique of radiotherapy, as well as the timing, sequence and duration of combination therapy will all affect treatment outcomes, justifying further in-depth investigation.

Effect of Immunotherapy and Stereotactic Body Radiation Therapy Sequencing on Local Control and Survival in Patients With Spine Metastases

Purpose

Stereotactic body radiation therapy (SBRT) is commonly used to treat spinal metastases in combination with immunotherapy (IT). The optimal sequencing of these modalities is unclear. This study aimed to investigate whether sequencing of IT and SBRT was associated with differences in local control (LC), overall survival (OS), and toxicity when treating spine metastases.

Methods and Materials

All patients at our institution who received spine SBRT from 2010 to 2019 with systemic therapy data available were reviewed retrospectively. The primary endpoint was LC. Secondary endpoints were toxicity (fracture and radiation myelitis) and OS. Kaplan-Meier analysis was used to determine whether IT sequencing (before versus after SBRT) and use of IT were associated with LC or OS.

Results

A total of 191 lesions in 128 patients met inclusion criteria with 50 (26%) lesions in 33 (26%) patients who received IT. Fourteen (11%) patients with 24 (13%) lesions received the first IT dose before SBRT, whereas 19 (15%) patients with 26 (14%) lesions received the first dose after SBRT. LC did not differ between lesions treated with IT before SBRT versus after SBRT (1 year 73% versus 81%, log rank = 0.275, P = .600). Fracture risk was not associated with IT timing (χ² = 0.137, P = .934) or receipt of IT (χ² = 0.508, P = .476), and no radiation myelitis events occurred. Median OS was 31.8 versus 6.6 months for the IT after SBRT versus IT before SBRT cohorts, respectively (log rank = 13.193, P < .001). On Cox univariate analysis and multivariate analysis, receipt of IT before SBRT and Karnofsky performance status <80 were associated with worse OS. IT treatment versus none was not associated with any difference in LC (log rank = 1.063, P = .303) or OS (log rank = 1.736, P = .188).

Conclusions

Sequencing of IT and SBRT was not associated with any difference in LC or toxicity, but delivering IT after SBRT versus before SBRT was associated with improved OS.

The abscopal effect: inducing immunogenicity in the treatment of brain metastases secondary to lung cancer and melanoma

PURPOSE

The phenomenon of radiation therapy (RT) causing regression of targeted lesions as well as lesions outside of the radiation field is known as the abscopal effect and is thought to be mediated by immunologic causes. This phenomena has been described following whole brain radiation (WBRT) and stereotactic radiosurgery (SRS) of brain metastasis (BM) in advanced melanoma and non-small-cell lung cancer (NSCLC). We systematically reviewed the available literature to identify which radiation modality and immunotherapy (IT) combination may elicit the abscopal effect, the optimal timing of RT and IT, and potential adverse effects inherent to the combination of RT and IT.

METHODS

Using PRISMA guidelines, a search of PubMed, Medline, and Web of Science was conducted to identify studies demonstrating the abscopal effect during treatment of NSCLC or melanoma with BM.

RESULTS

598 cases of irradiated BM of melanoma or NSCLC in 18 studies met inclusion criteria. The most commonly administered ITs included PD-1 or CTLA-4 immune checkpoint inhibitors (ICI), with RT most commonly administered within 3 months of ICI. Synergy between ICI and RT was described in 16 studies including evidence of higher tumor response within and outside of the irradiated field. In the 12 papers (n = 232 patients) that reported objective response rate (ORR) in patients with BM treated with RT and concurrent systemic IT, the non-weighted mean ORR was 49.4%; in the 5 papers (n = 110 patients) that reported ORR for treatment with RT or IT alone, the non-weighted mean ORR was 27.8%. No studies found evidence of significantly increased toxicity in patients receiving RT and ICI.

CONCLUSION

The combination of RT and ICIs may enhance ICI efficacy and induce more durable responses via the abscopal effect in patients with brain metastases of melanoma or NSCLC.

The abscopal effect: systematic review in patients with brain and spine metastases

Background

The abscopal effect is a rare phenomenon whereby local radiation induces a proposed immune-mediated anti-tumor effect at distant sites. Given the growing use of immunotherapies and systemic immune checkpoint inhibitors in neuro-oncologic practice, we aimed to review prior studies pertaining to this phenomenon in the context of tumor shrinkage both within the central nervous system as well as distant disease sites.

Methods

A systematic review in accordance with the PRISMA guidelines was conducted to identify all studies which assessed the abscopal effect in patients with treated metastatic cancer to the brain and/or spine. Articles were included if they reported the abscopal effect in patients (case studies) or if the abscopal effect was explicitly analyzed in case series with cohorts of patients with metastatic brain or spine tumors. Laboratory investigations and clinical trials investigating new therapies were excluded.

Results

Twenty reports met inclusion criteria [16 case reports, 4 case series (n = 160), total n = 174]. Case reports of the abscopal effect were in relation to the following cancers: melanoma (6 patients), breast cancer (3), lung adenocarcinoma (2), non-small-cell lung cancer (2), hepatocellular carcinoma (1), and renal cell carcinoma (1). Eleven patients had irradiation to the brain and 2 to the spine. Patients undergoing whole brain radiotherapy (6) had an average dose of 33.6 Gy over 8-15 fractions, and those undergoing stereotactic radiosurgery (5) had an average dose of 21.5 Gy over 1-5 fractions. One patient had radiation to the body and an intracranial abscopal effect was observed. Most common sites of extracranial tumor reduction were lung and lymph nodes. Ten case studies (57%) showed complete resolution of extra-CNS tumor burden. Median progression-free survival was 13 months following radiation. Four papers investigated incidence of abscopal effects in patients with metastatic melanoma to the brain who received immune checkpoint inhibitor therapy (n = 160); two papers found an abscopal effect in 35% and 52% of patients (n = 16, 21 respectively), and two papers found no evidence of abscopal effects (n = 61, 62).

Conclusions

Abscopal effects can occur following radiotherapy in patients with brain or spine metastases and is thought to be a result of increased anti-tumor immunity. The potential for immune checkpoint inhibitor therapy to be used in combination with radiotherapy to induce an abscopal effect is an area of active investigation.

Immunotherapy and radiotherapy in melanoma: a multidisciplinary comprehensive review

Melanoma is an extremely aggressive tumor and is considered to be an extremely immunogenic tumor because compared to other cancers it usually presents a well-expressed lymphoid infiltration. The aim of this paper is to perform a multidisciplinary comprehensive review of the evidence available about the combination of radiotherapy and immunotherapy for melanoma. Radiation, in fact, can increase tumor antigens visibility and promote priming of T cells but can also exert immunosuppressive action on tumor microenvironment. Combining radiotherapy with immunotherapy provides an opportunity to increase immunostimulatory potential of radiation. We therefore provide the latest clinical evidence about radiobiological rationale, radiotherapy techniques, timing, and role both in advanced and systemic disease (with a special focus on ocular melanoma and brain, liver, and bone metastases) with a particular attention also in geriatric patients. The combination of immunotherapy and radiotherapy seems to be a safe therapeutic option, supported by a clear biological rationale, even though the available data confirm that radiotherapy is employed more for metastatic than for non-metastatic disease. Such a combination shows promising results in terms of survival outcomes; however, further studies, hopefully prospective, are needed to confirm such evidence.

The role of stereotactic radiotherapy in addition to immunotherapy in the management of melanoma brain metastases: results of a systematic review

Aim of this study was to systematically review the literature to assess efficacy and safety of stereotactic radiotherapy (SRT) in combination with immunotherapy for the treatment of melanoma brain metastases (MBM). The literature was searched using PubMed, Scopus, and Embase. Studies comparing SRT plus immunotherapy versus SRT or immunotherapy alone were deemed eligible for inclusion. Two studies showed improved overall survival after SRT plus immunotherapy in melanoma cancer patients with brain metastases. Three studies reported data on LC and DFS showing as SRT plus immunotherapy did not improve local control and DFS rates. G3-G4 toxicity was reported in only one study (20% in the SRT plus immunotherapy group versus 23% in the immunotherapy group). Despite SRT plus concurrent immunotherapy seems associated with possible survival advantage and low ≥ G3 late toxicity rates, the quality of evidence is very low. Therefore, in patients with brain metastases from melanoma, SRT plus immunotherapy should be evaluated on an individual basis after discussion by a multidisciplinary team.

Development of a Clinically Oriented Model to Predict Antitumor Effects after PD-1/PD-L1 Inhibitor Therapy

Immune checkpoint inhibitors (ICI) have created an advanced shift in the treatment of lung cancer (LC), but the existing biomarkers were not in clinical and widespread use. The purpose of this study was to develop a new nomogram with immune factors used for monitoring the response to ICI therapy. LC patients with PD-1/PD-L1 inhibitors treatment were included in this analysis. The immune biomarkers and clinicopathological characteristic values at baseline were used to estimate the tumor response. The nomogram was based on the factors that were determined by univariate and multivariate Cox hazard analysis. For internal validation, bootstrapping with 1000 resamples was used. The concordance index (C-index) and calibration curve were used to determine the predictive accuracy and discriminative ability of the nomogram. Overall survival (OS) was estimated using the Kaplan-Meier method. Patients with lung metastasis (P = 0.010), higher baseline neutrophil-lymphocyte ratio (NLR) level (P < 0.001), lower baseline lymphocyte-monocyte (LMR) (P = 0.019), and lower CD3⁺CD8⁺ T cell count (P = 0.009) were significantly related to the tumor response. The above biomarkers were contained into the nomogram. The calibration plot for the probability of OS showed an optimal agreement between the actual observation and prediction by nomogram at 3 or 5 years after therapy. The C-index of nomogram for OS prediction was 0.804 (95% CI: 0.739-0.869). Decision curve analysis demonstrated that the nomogram was clinically useful. Moreover, patients were divided into two distinct risk groups for OS by the nomogram: low-risk group (OS: 17.27 months, 95% CI: 14.75-19.78) and high-risk group (OS: 6.11 months, 95% CI: 3.57-8.65), respectively. A nomogram constructed with lung metastasis baseline NLR, LMR, and CD3⁺CD8⁺ T cell count could be used to monitor and predict clinical benefit and prognosis in lung cancer patients within ICI therapy.

Evaluation of radio-immunotherapy sequence on immunological responses and clinical outcomes in patients with melanoma brain metastases (ELEKTRA)

In patients with melanoma brain metastases (MBM), a combination of radiotherapy (RT) with immune checkpoint inhibitors (ICI) is routinely used. However, the best sequence of radio-immunotherapy (RIT) remains unclear. In an exploratory phase 2 trial, MBM patients received RT (stereotactic or whole-brain radiotherapy depending on the number of MBM) combined with ipilimumab (ipi) ± nivolumab (nivo) in different sequencing (Rad-ICI or ICI-Rad). Comparators arms included patients treated with ipi-free systemic treatment or without RT (in MBM-free patients). The primary endpoints were radiological and immunological responses in the peripheral blood. Secondary endpoints were progression-free survival (PFS) and overall survival (OS). Of 106 screened, 92 patients were included in the study. Multivariate analysis revealed an advantage for patients starting with RT (Rad-ICI) for overall response rate (RR: p = .007; HR: 7.88 (95%CI: 1.76–35.27)) and disease control rate (DCR: p = .036; HR: 6.26 (95%CI: 1.13–34.71)) with a trend for a better PFS (p = .162; HR: 1.64 (95%CI: 0.8–3.3)). After RT plus two cycles of ipi-based ICI in both RIT sequences, increased frequencies of activated CD4, CD8 T cells and an increase in melanoma-specific T cell responses were observed in the peripheral blood. Lasso regression analysis revealed a significant clinical benefit for patients treated with Rad-ICI sequence and immunological features, including high frequencies of memory T cells and activated CD8 T cells in the blood. This study supports increasing evidence that sequencing RT followed by ICI treatment may have better effects on the immunological responses and clinical outcomes in MBM patients.

Brain metastases: An update on the multi-disciplinary approach of clinical management

IMPORTANCE

Brain metastasis (BM) is the most common malignant intracranial neoplasm in adults with over 100,000 new cases annually in the United States and outnumbering primary brain tumors 10:1.

OBSERVATIONS

The incidence of BM in adult cancer patients ranges from 10-40%, and is increasing with improved surveillance, effective systemic therapy, and an aging population. The overall prognosis of cancer patients is largely dependent on the presence or absence of brain metastasis, and therefore, a timely and accurate diagnosis is crucial for improving long-term outcomes, especially in the current era of significantly improved systemic therapy for many common cancers. BM should be suspected in any cancer patient who develops new neurological deficits or behavioral abnormalities. Gadolinium enhanced MRI is the preferred imaging technique and BM must be distinguished from other pathologies. Large, symptomatic lesion(s) in patients with good functional status are best treated with surgery and stereotactic radiosurgery (SRS). Due to neurocognitive side effects and improved overall survival of cancer patients, whole brain radiotherapy (WBRT) is reserved as salvage therapy for patients with multiple lesions or as palliation. Newer approaches including multi-lesion stereotactic surgery, targeted therapy, and immunotherapy are also being investigated to improve outcomes while preserving quality of life.

CONCLUSION

With the significant advancements in the systemic treatment for cancer patients, addressing BM effectively is critical for overall survival. In addition to patient's performance status, therapeutic approach should be based on the type of primary tumor and associated molecular profile as well as the size, number, and location of metastatic lesion(s).

Whole Brain Irradiation or Stereotactic RadioSurgery for five or more brain metastases (WHOBI-STER): A prospective comparative study of neurocognitive outcomes, level of autonomy in daily activities and quality of life

•

The main aim of MBM treatment is to palliate neurological symptoms and to maintain an adequate QoL.

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SRT could be the “new standard” over WBI in the management of MBM patients.

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Neurocognitive functions could deteriorate more after WBI than after SRT.

Aims

To evaluate neurocognitive performance, daily activity and quality of life (QoL), other than usual oncologic outcomes, among patients with brain metastasis ≥5 (MBM) from solid tumors treated with Stereotactic Brain Irradiation (SBI) or Whole Brain Irradiation (WBI).

Methods

This multicentric randomized controlled trial will involve the enrollment of 100 patients (50 for each arm) with MBM ≥ 5, age ≥ 18 years, Karnofsky Performance Status (KPS) ≥ 70, life expectancy > 3 months, known primary tumor, with controlled or controllable extracranial disease, baseline Montreal Cognitive Assessment (MoCA) score ≥ 20/30, Barthel Activities of Daily Living score ≥ 90/100, to be submitted to SBI by LINAC with monoisocentric technique and non-coplanar arcs (experimental arm) or to WBI (control arm). The primary endpoints are neurocognitive performance, QoL and autonomy in daily-life activities variations, the first one assessed by MoCa Score and Hopkins Verbal Learning Test-Revised, the second one through the EORTC QLQ-C15-PAL and QLQ-BN-20 questionnaires, the third one through the Barthel Index, respectively. The secondary endpoints are time to intracranial failure, overall survival, retreatment rate, acute and late toxicities, changing of KPS. It will be considered significant a statistical difference of at least 30% between the two arms (statistical power of 80% with a significance level of 95%).

Discussion

Several studies debate what is the decisive factor accountable for the development of neurocognitive decay among patients undergoing brain irradiation for MBM: radiation effect on clinically healthy brain tissue or intracranial tumor burden? The answer to this question may come from the recent technological advancement that allows, in a context of a significant time saving, improved patient comfort and minimizing radiation dose to off-target brain, a selective treatment of MBM simultaneously, otherwise attackable only by WBI. The achievement of a local control rate comparable to that obtained with WBI remains the fundamental prerequisite.

Trial registration

NCT number: NCT04891471.

Role of stereotactic radiosurgery for the treatment of brain metastasis in the era of immunotherapy: A systematic review on current evidences and predicting factors

Stereotactic radiosurgery (SRS) in combination with immunotherapy (IT) is increasingly used in the setting of melanoma and non-small cell lung cancer (NSCLC) brain metastases (BM). The synergistic properties of this treatment combination are still not deeply understood. IT-SRS appropriate combination has been envisioned as a strategic point in patients' management. Authors performed a systematic review on current evidences up to December 2020. The impact of SRS-IT and different IT schedules on survival, local/distant intracranial control and toxicity, as well as predictive factors for relevant oncological and radiological outcomes has been analyzed. Authors retrieved 23 pertinent studies. Combining SRS with IT resulted in a significant improvement in OS and lesion response with no increase in radionecrosis, hemorrhage or other complications. The present review suggests that combining IT to SRS is safe and effective in providing a significant improvement in relevant clinical and radiological outcomes in melanoma and NSCLC BMs patients.

Single- and hypofractionated stereotactic radiosurgery for large (> 2 cm) brain metastases: a systematic review

PURPOSE

Since frameless stereotactic radiosurgery (SRS) techniques have been recently introduced, hypofractionated SRS (HF-SRS) for large brain metastases (BMs) is gradually increasing. To verify the efficacy and safety of HF-SRS for large BMs, we aimed to perform a systematic review and compared them with SF-SRS.

METHODS

We systematically searched the studies regarding SF-SRS or HF-SRS for large (> 2 cm) BM from databases including PubMed, Embase, and the Cochrane Library on July 31, 2018. Biologically effective dose with the α/β ratio of 10 (BED₁₀), 1-year local control (LC), and radiation necrosis (RN) were compared between the two groups, with the studies being weighted by the sample size.

RESULTS

The 15 studies with 1049 BMs that described 1-year LC and RN were included. HF-SRS tended to be performed in larger tumors; however, higher mean BED₁₀ (50.1 Gy₁₀ versus 40.4 Gy₁₀, p < 0.0001) was delivered in the HF-SRS group, which led to significantly improved 1-year LC (81.6 versus 69.0%, p < 0.0001) and 1-year overall survival (55.1 versus 47.2%, p < 0.0001) in the HF-SRS group compared to the SF-SRS group. In contrast, the incidence of radiation toxicity was significantly decreased in the HF-SRS group compared to the SF-SRS group (8.0 versus 15.6%, p < 0.0001).

CONCLUSION

HF-SRS results in better LC of large BMs while simultaneously reducing RN compared to SF-SRS. Thus, HF-SRS should be considered a priority for SF-SRS in patients with large BMs who are not suitable to undergo surgical resection.

Bevacizumab for stereotactic radiosurgery-induced radiation necrosis in patients with non-small cell lung cancer treated with immune check-point inhibitors

BACKGROUND

Bevacizumab was shown to be effective in the treatment of brain radiation necrosis (RN) attributed to the use of stereotactic radiosurgery (SRS). Data on its efficacy and safety in non-small cell lung cancer (NSCLC) patients treated with immune check-point inhibitors (ICI) is lacking.

METHODS

A multi-center retrospective analysis of all consecutive patients with NSCLC treated with ICI, who received bevacizumab for post-SRS RN between April 2017 and June 2020. Improvement in RN-associated symptoms, RN radiological improvement, and decrease in corticosteroid dose following bevacizumab initiation were assessed.

RESULTS

Thirteen patients were identified. The median time from diagnosis of RN to initiation of bevacizumab was 3 months (range 1.1-7.8 months), and the median number of bevacizumab cycles before assessment was 2 (range, 1-5). Patients continued ICI during treatment with bevacizumab. Improvement in RN-associated symptoms was observed in 11 patients (85%). In ten patients (77%) the daily dose of dexamethasone was decreased. Radiological improvement of RN occurred in all 11 cases available for radiological assessment (100%). Treatment was withheld in two patients for grade 3-4 toxicity. At a median follow up of 11.9 months (range 2.0-35.4 months), one patient experienced a recurrent episode of RN; the estimated median survival since RN diagnosis was 21.9 months (95% CI 3.8-40.2 months).

CONCLUSION

Treatment with bevacizumab appears to be safe and effective for the treatment of SRS-induced RN in patients with NSCLC treated with ICI. This is the first series to report on the use of bevacizumab in this clinical scenario.

Emerging principles of brain immunology and immune checkpoint blockade in brain metastases

Brain metastases are the most common type of brain tumours, harbouring an immune microenvironment that can in principle be targeted via immunotherapy. Elucidating some of the immunological intricacies of brain metastases has opened a therapeutic window to explore the potential of immune checkpoint inhibitors in this globally lethal disease. Multiple lines of evidence suggest that tumour cells hijack the immune regulatory mechanisms in the brain for the benefit of their own survival and progression. Nonetheless, the role of the immune checkpoint in the complex interplays between cancers cells and T cells and in conferring resistance to therapy remains under investigation. Meanwhile, early phase trials with immune checkpoint inhibitors have reported clinical benefit in patients with brain metastases from melanoma and non-small cell lung cancer. In this review, we explore the workings of the immune system in the brain, the immunology of brain metastases, and the current status of immune checkpoint inhibitors in the treatment of brain metastases.

Ipilimumab and Stereotactic Radiosurgery with CyberKnife® System in Melanoma Brain Metastases: A Retrospective Monoinstitutional Experience

Simple Summary

Retrospective studies have shown a survival advantage in combining ipilimumab with radiotherapy in patients with melanoma brain metastases (MBMs). However, these studies did not clarify the correct timing between the two methods. The aims of our study were to demonstrate the efficacy and toxicity of stereotactic radiotherapy/radiosurgery on MBMs in combination with ipilimumab and estimate the correct timing of treatments to improve patients’ outcomes.

Abstract

The median overall survival (OS) and local control (LC) of patients with melanoma brain metastases (MBMs) are poor even with immune checkpoint inhibitors and/or radiotherapy (RT). The aims of the study were to evaluate the association and timing of stereotactic radiotherapy (SRT)/radiosurgery (SRS) performed with the CyberKnife^® System and ipilimumab (IPI). A total of 63 MBMs patients were analyzed: 53 received RT+IPI and 10 RT alone. Therefore, the patients were divided into four groups: RT PRE-PI (>4 weeks before IPI) (18), RT CONC-IPI (4 weeks before/between first and last cycle/within 3 months of last cycle of IPI) (20), RT POST-IPI (>3 months after IPI) (15), and NO-IPI (10). A total of 127 lesions were treated: 75 with SRS (one fraction) and 24 with SRT (three to five fractions). The median follow-up was 10.6 months. The median OS was 10.6 months for all patients, 10.7 months for RT+IPI, and 3.3 months for NO-IPI (p = 0.96). One-year LC was 50% for all patients, 56% for RT+IPI, and 18% for NO-IPI (p = 0.08). The 1-year intracranial control was 45% for all patients, 44% for RT+IPI, and 51% for NO-IPI (p = 0.73). IPI with SRS/SRT in MBMs treatment could improve LC. However, the impact and timing of the two modalities on patients’ outcomes are still unclear.

Survival Benefits of Anti-PD-1 Therapy in Combination With Radiotherapy in Chinese Melanoma Patients With Brain Metastasis

Limited data reported the synergistic anti-tumor effect of anti-PD-1 (programmed death 1) therapy and radiotherapy on melanoma BM (brain metastasis). And the efficacy in the Chinese population is unclear. This study aimed to evaluate the efficacy of anti-PD-1 therapy and radiotherapy in Chinese melanoma patients with BM. We retrospectively reviewed 96 consecutive melanoma patients with BM treated at Sun Yat-Sen University Cancer Center. Patient demographics, BM characteristics and treatment details were carefully collected. The intracranial PFS (progression free survival) and OS (overall survival) were estimated using the Kaplan-Meier method. Twenty-five patients were treated with anti-PD-1 therapy and radiotherapy. Eighteen (72.0%) patients had SBRT (stereotactic body radiation therapy) or SRS (stereotactic radiosurgery) for BM, 1 (4.0%) patient had WBRT (whole brain radiation therapy), 6 (24.0%) patients had SBRT/SRS and WBRT. The median treatment period of anti-PD-1 therapy was 10.77 months. Objective intracranial response was observed in 15 (60%) patients, and 5 (20%) patients achieved CR (complete response). After a median follow-up of 16 months, 11 (44%) patients experienced intracranial PD (progressive disease), and 15 (60%) patients died. The median intracranial PFS and OS were 10.73 months (range, 1.67–38.83 months) and 15.87 months (range, 2.47–41.50 months), respectively. The 1-year intracranial PFS and OS were 61.9% (95% CI, 44.1–86.9%) and 62.5% (95%CI, 45.8–85.2%), respectively. Patients with BM can benefit from a combination of anti-PD-1 therapy and radiotherapy. It merits further investigation in melanoma patients with BM.

Immunotherapy and radiation therapy sequencing: State of the data on timing, efficacy, and safety

Radiation therapy exerts a tumoricidal local effect as well as both local and systemic immunomodulation. Immune checkpoint blockade has become a widely used treatment modality across cancer types with a rapidly growing list of agents and US Food and Drug Administration-approved indications. Moreover, there may be synergy between radiation therapy and immune checkpoint blockade. Various strategies have been used, but the optimal sequencing of these therapies is unclear. In this review, the authors discuss the major mechanisms of available immune checkpoint inhibitors and explore the available preclinical and clinical evidence regarding treatment sequencing. They also review safety considerations and conclude with possible future directions.

Brain Radiation Induced Extracranial Abscopal Effects in Metastatic Melanoma

Historically, the brain has been viewed as a specialized neurovascular inert organ with a distinctive immune privilege. Therefore, radiation-induced extracranial abscopal effects would be considered an unusual phenomenon due to the difficulty of the immunogenic signaling molecules to travel across the blood-brain barrier (BBB). However, it is now possible that localized central nervous system radiation has the ability to disrupt the structural integrity of the BBB and increase its endothelial permeability allowing the free passage of immunogenic responses between the intracranial and extracranial compartments. Thus, the nascent tumor-associated antigens produced by localized brain radiation can travel across the BBB into the rest of the body to modulate the immune system and induce extracranial abscopal effects. In clinical practice, localized brain radiation therapy-induced extracranial abscopal effects are a rarely seen phenomenon in metastatic melanoma and other advanced cancers. In this article, we provide a detailed overview of the current state of knowledge and clinical experience of central nervous system radiation-induced extracranial abscopal effects in patients with malignant melanoma. Emerging data from a small number of case reports and cohort studies of various malignancies has significantly altered our earlier understanding of this process by revealing that the brain is neither isolated nor passive in its interactions with the body's immune system. In addition, these studies provide clinical evidence that the brain is capable of interacting actively with the extracranial peripheral immune system. Thus, localized radiation treatment to 1 or more locations of brain metastases can induce extracranial abscopal responses. Collectively, these findings clearly demonstrate that localized brain radiation therapy-induced abscopal effects traverses the BBB and trigger tumor regression in the nonirradiated extracranial locations.

Immunostimulatory Effects of Radiotherapy for Local and Systemic Control of Melanoma: A Review

Recently, modern therapies involving immune checkpoint inhibitors, cytokines, and oncolytic virus have been developed. Because of the limited treatment effect of modern therapy alone, the immunostimulatory effect of radiotherapy attracted increasing attention. The combined use of radiotherapy and modern therapy has been examined clinically and non-clinically, and its effectiveness has been confirmed recently. Because melanomas have high immunogenicity, better therapeutic outcomes are desired when using immunotherapy. However, sufficient therapeutic effects have not yet been achieved. Thus far, radiotherapy has been used only for local control of tumors. Although extremely rare, radiotherapy has also been reported for systemic control, i.e., abscopal effect. This is thought to be due to an antitumor immune response. Therefore, we herein summarize past information on not only the mechanism of immune effects on radiotherapy but also biomarkers reported in case reports on abscopal effects. We also reviewed the animal model suitable for evaluating abscopal effects. These results pave the way for further basic research or clinical studies on new treatment methods for melanoma. Currently, palliative radiation is administered to patients with metastatic melanoma for local control. If it is feasible to provide both systemic and local control, the treatment benefit for the patients is very large.

The Association of the Sequence of Immunotherapy With the Survival of Unresectable Pancreatic Adenocarcinoma Patients: A Retrospective Analysis of the National Cancer Database

Background: Immunotherapy has shown great success in various malignancies. However, its efficacy in pancreatic ductal adenocarcinoma (PDAC) remains a challenge, and the lack of understanding about the appropriate timing of immunotherapy with other standard-of-care cancer treatments may be one of the causes. The objective of the current study is to investigate the impact of the timing of immunotherapy with chemotherapy and radiation therapy (RT) on the overall survival (OS) of PDAC patients who did not receive surgical resection of the pancreatic tumor.

Materials and Methods: Patients with pancreatic adenocarcinoma who did not receive surgical resection of the pancreatic tumor were identified from the National Cancer Database (NCDB). Cox proportional hazard models were employed to compare the OS between patients who received immunotherapy with chemotherapy or RT with a different sequence of treatment. The multivariable analysis was adjusted for age of diagnosis, race, sex, place of living, income, education, treatment facility type, insurance status, and year of diagnosis.

Results: In total, 705 patients received chemotherapy and immunotherapy, while 226 received radiation therapy and immunotherapy. In the multivariable analysis, there was no significant difference in the OS of patients who started immunotherapy 31–90 days before the start of chemotherapy with a hazard ratio (HR) of [HR:1.057 (CI: 0.716–1.56; p < 0.781)] and patients who started immunotherapy 91–180 days before the start of chemotherapy [HR: 0.900 (CI: 0.584–1.388; p < 0.635)] compared to patients who started chemotherapy and immunotherapy within 30 days of each other. There was also no significant difference in the OS of patients who started RT> 30 days before the start of immunotherapy [HR: 0.636 (CI: 0.346–1.171; p < 0.146)] and patients who started immunotherapy > 30 days before the start of RT [HR: 0.660 (CI: 0.328–1.329; p < 0.246)] compared to patients who started RT and immunotherapy within 30 days of each other.

Conclusion: The sequence of immunotherapy with chemotherapy or RT was not associated with improved OS. Future studies with a larger subgroup sample size investigating the impact of the timing of immunotherapy with chemotherapy and RT on the OS of PDAC patients who do not receive surgical resection of the pancreatic tumor are needed.

Immune Therapy for Central Nervous System Metastasis

Brain metastases lead to substantial morbidity and mortality among patients with advanced malignancies. Although treatment options have traditionally included largely palliative measures, studies of brain metastasis response to immunotherapy are promising. Immune checkpoint inhibitors have shown efficacy in studies of patients with melanoma, renal cell carcinoma, and lung cancer brain metastases. Patients with brain metastases are more frequently included in clinical trials, ushering in a new era in immunotherapy and management for patients with brain metastases. Gaining an understanding of the molecular determination for response to immunotherapies remains a major challenge and is an active area of future research.

Brain metastasis formation and irradiation by stereotactic radiation therapy combined with immunotherapy: A systematic review

INTRODUCTION

Brain metastasis (BM) is a complex process that implies immune cells and microglia. Stereotactic radiation therapy (SRT) and immunotherapy (IT) are established to increase the immune response; but their association has never been prospectively studied.

MATERIALS AND METHODS

Two reviewers performed a systematic review in original papers published up to September 2019. We analysed OS, local (mLRF) and regional (mBRF) median disease-free survival in patients with BMs after SRT with and without IT.

RESULTS

Upon 14 studies, eleven concerned melanoma, three concerned lung cancers. SRT-IT showed better OS, mLRF and mBRF than SRT. mBRF was better if SRT was performed with short delay from IT. No higher rates of radionecrosis and haemorrhage were found among groups.

CONCLUSION

This review suggests SRT combined to IT in melanoma is safe and could provide better BRF, suggesting a lymphocytic immune reaction in brain. No improvement trend was found in lung cancer BM.

Current approaches to the management of brain metastases

Brain metastases are a very common manifestation of cancer that have historically been approached as a single disease entity given the uniform association with poor clinical outcomes. Fortunately, our understanding of the biology and molecular underpinnings of brain metastases has greatly improved, resulting in more sophisticated prognostic models and multiple patient-related and disease-specific treatment paradigms. In addition, the therapeutic armamentarium has expanded from whole-brain radiotherapy and surgery to include stereotactic radiosurgery, targeted therapies and immunotherapies, which are often used sequentially or in combination. Advances in neuroimaging have provided additional opportunities to accurately screen for intracranial disease at initial cancer diagnosis, target intracranial lesions with precision during treatment and help differentiate the effects of treatment from disease progression by incorporating functional imaging. Given the numerous available treatment options for patients with brain metastases, a multidisciplinary approach is strongly recommended to personalize the treatment of each patient in an effort to improve the therapeutic ratio. Given the ongoing controversies regarding the optimal sequencing of the available and expanding treatment options for patients with brain metastases, enrolment in clinical trials is essential to advance our understanding of this complex and common disease. In this Review, we describe the key features of diagnosis, risk stratification and modern paradigms in the treatment and management of patients with brain metastases and provide speculation on future research directions.

Radiosurgery and Immunotherapy in the Treatment of Brain Metastases

Radiation therapy represents a mainstay of treatment for patients with brain metastases. Recently, the widespread adoption of immune checkpoint blockade has led to keen interest in treating cancers with checkpoint inhibitors in place of, or as an adjunct to, traditional chemotherapy. However, with the exception of melanoma, immune checkpoint blockade in solid tumors has failed to achieve significant brain control in patients with brain metastases. The possibility of combining immune checkpoint blockade with radiation for the treatment of brain and other metastases represents an exciting new strategy that is in its early stages of investigation. Success with this combinatorial strategy has the potential to result in enhanced rates of brain control, less brain exposure to radiation, and improved cognitive outcomes. In this review, we discuss the mechanisms behind this synergy, describe its limitations, and suggest ways to move the field forward.

Integration of stereotactic radiosurgery or whole brain radiation therapy with immunotherapy for treatment of brain metastases

The prognosis of brain metastases (BM) is traditionally poor. BM are mainly treated by local radiotherapy, including stereotactic radiosurgery (SRS) or whole brain radiation therapy (WBRT). Recently, immunotherapy (i.e., immune checkpoint inhibitors, ICI) has demonstrated a survival advantage in multiple malignancies commonly associated with BM. Individually, radiotherapy and ICI both treat BM efficiently; hence, their combination seems logical. In this review, we summarize the existing preclinical and clinical evidence that supports the applicability of radiotherapy as a sensitizer of ICI for BM. Further, we discuss the optimal timing at which radiotherapy and ICI should be administered and review the safety of the combination therapy. Data from a few clinical studies suggest that combining SRS or WBRT with ICI simultaneously rather than consecutively potentially enhances brain abscopal-like responses and survival. However, there is a lack of conclusion about the definition of "simultaneous"; the cumulative toxic effect of the combined therapies also requires further study. Thus, ongoing and planned prospective trials are needed to further explore and validate the effect, safety, and optimal timing of the combination of immunotherapy with radiotherapy for patients with BM.

Concurrent Radiosurgery and Immune Checkpoint Inhibition: Improving Regional Intracranial Control for Patients With Metastatic Melanoma

OBJECTIVES

The anti-CTLA-4 and antiprogrammed cell death-1 (PD-1) therapies have significantly improved survival of patients with metastatic melanoma. However, there is limited data regarding the interaction between immunotherapy (IT) and stereotactic radiosurgery (SRS) in patients with brain metastasis, particularly how combination therapy may affect toxicity and intracranial tumor control.

METHODS

We retrospectively reviewed 26 patients with metastatic melanoma who received immune check point inhibitors and SRS for brain metastasis from 2011 to 2017. We evaluated lesions receiving SRS concurrently (within 30 days) and sequentially with IT. Overall survival (OS), local control (LC), and regional progression free survival (RPFS) were determined.

RESULTS

In total, 26 patients and 90 lesions were treated using pembrolizumab, nivolumab and/or ipilimumab, sequentially, or concurrently with SRS. Median follow-up was 18.9 months (range, 4.9 to 62.3 mo). Median overall survival was 26.1 months. There were 3 local failures, but no significant difference between the 2 groups. Following concurrent SRS and immunotherapy, patients had a significantly longer period of intracranial progression free survival than those treated with nonconcurrent therapy, 19 months versus 3.4 months (P<0.0001). No grade 4-5 toxicities were observed.

CONCLUSIONS

Patients with melanoma metastatic to brain treated with SRS and immune checkpoint inhibitors had favorable median survival of 26.1 months compared with historical controls. Patients receiving immunotherapy within 30 days of SRS had significantly improved regional intracranial progression free survival compared with patients receiving sequential therapy. Our findings suggest synergy between checkpoint inhibitor immunotherapy and radiosurgery. Further studies are needed to confirm these findings.

Efficacy and safety of immune checkpoint inhibitors in a Danish real life non-small cell lung cancer population: a retrospective cohort study

Background: To investigate effect and toxicity of immune checkpoint inhibition (ICI) in a Danish real-life non-small cell lung cancer (NSCLC) population. By including patients underrepresented in clinical trials, such as those with brain metastasis (BM), higher age, more comorbidity and poorer performance status (ECOG), comparison of unselected patients to clinical trial populations is possible. Material and methods: Real life data were gathered from 118 consecutive NSCLC patients with incurable NSCLC treated with ICI at the Department of Oncology at the University Hospital of Odense, Denmark from September 2015 to April 2018. Immune-related adverse events (irAEs) grades 3-5 were registered prospectively during the same period. Additional patient related data were obtained retrospectively from patients' files. Overall survival (OS) and progression-free survival (PFS) were calculated using the Kaplan-Meier estimates, the log-rank test and cox regression analysis performed for factors affecting survival. Results: Median age for patients was 66 years (IQR 59-71) and 62 years (range: 55-64) for those with BM. Females 63%; adenocarcinoma (AC)/squamous/others 69%/23%/8%; ECOG ≥ 2 10%; bone/brain/liver metastases 36%/18%/15%; PD-L1 (TPS) <1%/ ≥ 1%/ ≤ 49%/ ≥ 50%/NR: 3%/14%/68%/15%; baseline autoimmunity 10%, Charlson's Comorbidity Index Score (CCIS) ≥ 2 39%, treatment line: 1st/2nd/ ≥ 3rd 39%/30%/31%. Median OS for patients receiving ICI in ≥2 line was 11.5 months versus not reached in first line (HR 2.6, [95% CI: 1.3-5.0], p = .005). For patients with BM, the median OS was 8.2 months (HR 1.38, [95% CI: 0.7-2.5], p = .37). Twenty-four percent of patients terminated ICI due to irAE grades 3-5 alone (grade 5, n  =  1), which were not associated with higher age or BM. Conclusions: OS and PFS were comparable to clinical trial reports. Long-lasting remission is also possible in patients with BM. Real-life populations have higher rates of irAE grades 3 and 4 than reported in clinical trials, but it does not seem to impact median OS.

A translational concept of immuno-radiobiology

BACKGROUND

Traditional concepts of radiobiology model the direct radiation-induced cellular cytotoxicity but are not focused on late and sustained effects of radiation. Recent experimental data show the close involvement of immunological processes.

METHODS

Based on systematic PubMed searches, experimental data on immunological radiation effects are summarized and analyzed in a non-quantitative descriptive manner to provide a translational perspective on the immuno-modulatory impact of radiation in cancer.

RESULTS

Novel experimental findings document that sustained radiation effects are ultimately mediated through systemic factors such as cytotoxic CD8+ T cells and involve a local immuno-stimulation. Increased tumor infiltration of CD8+ T cell is a prerequisite for long-term radiation effects. CD8+ T cell depletion induces radio-resistance in experimental tumors. The proposed sequence of events involves radiation-damaged cells that release HMGB1, which activates macrophages via TLR4 to a local immuno-stimulation via TNF, which contributes to maturation of DCs. The mature DCs migrate to lymph nodes where they trigger effective CD8+ T cell responses. Radiation effects are boosted, when the physiological self-terminating negative feedback of immune reactions is antagonised via blocking of TGF-β or via checkpoint inhibition with involvement of CD8+ T cells as common denominator.

CONCLUSION

The concept of immuno-radiobiology emphasizes the necessity for a functional integrity of APCs and T cells for the long-term effects of radiotherapy. Local irradiation at higher doses induces tumor infiltration of CD8+ T cells, which can be boosted by immunotherapy. More systematic research is warranted to better understand the immunological effects of escalating radiation doses.

Safety of combining radiotherapy with immune-checkpoint inhibition

Immune-checkpoint inhibitors targeting cytotoxic T- lymphocyte antigen 4 (CTLA-4), programmed cell death protein 1 (PD-1), or programmed cell death 1 ligand 1 (PD-L1) have transformed the care of patients with a wide range of advanced-stage malignancies. More than half of these patients will also have an indication for treatment with radiotherapy. The effects of both radiotherapy and immune-checkpoint inhibition (ICI) involve a complex interplay with the innate and adaptive immune systems, and accumulating evidence suggests that, under certain circumstances, the effects of radiotherapy synergize with those of ICI to augment the antitumour responses typically observed with either modality alone and thus improve clinical outcomes. However, the mechanisms by which radiotherapy and immune-checkpoint inhibitors synergistically modulate the immune response might also affect both the type and severity of treatment-related toxicities. Moreover, in patients receiving immune-checkpoint inhibitors, the development of immune-related adverse events has been linked with superior treatment responses and patient survival durations, suggesting a relationship between the antitumour and adverse autoimmune effects of these agents. In this Review, we discuss the emerging data on toxicity profiles related to immune-checkpoint inhibitors and radiotherapy, both separately and in combination, their potential mechanisms, and the approaches to managing these toxicities.

Radiation therapy and immunotherapy: what is the optimal timing or sequencing?

Radiotherapy is a component of the standard of care for many patients with locally advanced nonmetastatic tumors and increasingly those with oligometastatic tumors. Despite encouraging advances in local control and progression-free and overall survival outcomes, continued manifestation of tumor progression or recurrence leaves room for improvement in therapeutic efficacy. Novel combinations of radiation with immunotherapy have shown promise in improving outcomes and reducing recurrences by overcoming tumor immune tolerance and evasion mechanisms via boosting the immune system's ability to recognize and eradicate tumor cells. In this review, we discuss preclinical and early clinical evidence that radiotherapy and immunotherapy can improve treatment outcomes for locally advanced and metastatic tumors, elucidate underlying molecular mechanisms and address strategies to optimize timing and sequencing of combination therapy for maximal synergy.

Impact of radiotherapy administered simultaneously with systemic treatment in patients with melanoma brain metastases within MelBase, a French multicentric prospective cohort

BACKGROUND

Melanoma brain metastases (MBMs) are historically associated with poor prognosis. Radiation therapy is conventionally associated with a high local control rate. Development of targeted therapy and immunotherapy has improved overall survival (OS) and intracranial response rate, but about 50% of patients failed to respond to these novel therapies. The objective of this study was to assess the impact of combined radiotherapy (cRT) on overall survival in a large multicenter real-life prospective cohort of patients with MBM treated with immunotherapy or targeted therapy.

PATIENTS AND METHODS

Clinical data from 262 patients with MBM were collected via MelBase, a French multicentric biobank prospectively enrolling unresectable stage III or IV melanoma. Two groups were defined: patients receiving cRT (cRT group) or not receiving cRT (no-cRT group). Primary end-point was OS. Propensity score weighting was used to correct for indication bias.

RESULTS

Among the 262 patients, 93 (35%) received cRT (cRT group). The patients were treated with immunotherapy in 69% and 60% and with targeted therapy in 31% and 40% of the cRT and no-cRT groups, respectively. With a median follow-up of 6.9 months, median OS was 16.8 months and 6.9 months in the cRT and no-cRT groups, respectively. After propensity score weighting, cRT was associated with longer OS (hazard ratio = 0.6, 95% confidence interval: 0.4-0.8; p=0.007). Median OS after ponderation was 15.3 months and 6.2 months in the cRT and no-cRT groups, respectively.

CONCLUSION

This study shows that cRT may be associated with a significant decrease of 40% in the risk of death in patients with MBM treated with systemic therapy.

Extracranial Abscopal Responses after Radiation Therapy for Intracranial Metastases: A Review of the Clinical Literature and Commentary on Mechanism

The current literature contains a small number of case series and individual case reports that describe radiographic regression of extracranial tumors after treatment of one or more brain metastases with radiation therapy. These observations suggest an abscopal effect that traverses the blood-brain barrier. The purpose of this review is to describe the clinical evidence for this phenomenon and potential mechanistic relationships between radiation, the blood-brain barrier, and the abscopal effect. Among reported cases, the majority of patients received systemic immunotherapy, which is consistent with an immunologic mechanism underlying abscopal responses. Preclinical data suggest that radiation may play multiple roles in this process, including the release of tumor-associated antigens and disruption of the blood-brain barrier. Future studies investigating the abscopal effect would benefit from more rigorous methods to control for patient and treatment factors that may affect distant tumor response.

The value of immunotherapy in head and neck cancer

INTRODUCTION

Head and neck squamous cell carcinomas (HNSCC) previously had limited treatment options once patients had progressed on systemic chemotherapy. With recent advances, immunotherapy now plays an important role in the treatment of advanced disease with improved outcomes as compared to cytotoxic chemotherapy.

AREAS COVERED

This article reviews the effects of the immune system and how it influences the development and response to HNSCC therapy. We additionally provide a summary of immunotherapy treatments available as well as their applicable clinical trials that led to their approval.

EXPERT COMMENTARY

The challenges that need to be addressed in order to maximize the benefits of immunotherapy in HNSCC are the selection criteria for immune checkpoint inhibitors and the optimization of combination regimens of immunotherapeutics or chemo-immunotherapy. Furthermore, there remains to be a lack of knowledge in how to incorporate molecular biomarkers as predictors of response to HNSCC immunotherapy.

Preoperative Stereotactic Radiosurgery for Brain Metastases

Stereotactic radiosurgery (SRS) is increasingly utilized to treat the resection cavity following resection of brain metastases and recent randomized trials have confirmed postoperative SRS as a standard of care. Postoperative SRS for resected brain metastases improves local control compared to observation, while also preserving neurocognitive function in comparison to whole brain radiation therapy (WBRT). However, even with surgery and SRS, rates of local recurrence at 1 year may be as high as 40%, especially for larger cavities, and there is also a known risk of leptomeningeal disease after surgery. Additional treatment strategies are needed to improve control while maintaining or decreasing the toxicity profile associated with treatment. Preoperative SRS is discussed here as one such approach. Preoperative SRS allows for contouring of an intact metastasis, as opposed to an irregularly shaped surgical cavity in the post-op setting. Delivering SRS prior to surgery may also allow for a “sterilizing” effect, with the potential to increase tumor control by decreasing intra-operative seeding of viable tumor cells beyond the treated cavity, and decreasing risk of leptomeningeal disease. Because there is no need to treat brain surrounding tumor in the preoperative setting, and since the majority of the high dose volume can then be resected at surgery, the rate of symptomatic radiation necrosis may also be reduced with preoperative SRS. In this mini review, we explore the potential benefits and risks of preoperative vs. postoperative SRS for brain metastases as well as the existing literature to date, including published outcomes with preoperative SRS.

Stereotactic Radiosurgery and Immune Checkpoint Inhibitors in the Management of Brain Metastases

Brain metastases traditionally carried a poor prognosis with an overall survival of weeks to months in the absence of treatment. Radiation therapy modalities include whole brain radiation therapy (WBRT) and stereotactic radiosurgery (SRS). WBRT delivers a relatively low dose of radiation, has neurocognitive sequelae, and has not been investigated for its immunostimulatory effects. Furthermore, WBRT exposes the entire intracranial tumor immune microenvironment to radiation. SRS delivers a high dose of conformal radiation with image guidance to minimize dose to surrounding normal brain tissue, and appears to promote anti-tumor immunity. In parallel with many of these discoveries, immune checkpoint inhibitors (ICIs) have demonstrated a survival advantage in multiple malignancies commonly associated with brain metastases (e.g., melanoma). Combination SRS and ICI are theorized to be synergistic in anti-tumor immunity directed to brain metastases. The purpose of this review is to explore the synergy of SRS and ICIs, including pre-clinical data, existing clinical data, and ongoing prospective trials.

Immune Checkpoint Inhibitors for the Treatment of Central Nervous System (CNS) Metastatic Disease

While the CNS has long been viewed as an immune-privileged environment, a paradigm shift in neuro-immunology has elevated the role of systemic immunotherapy for the treatment of metastatic disease. Increasing knowledge regarding the presence of a CNS lymphatic system and the physical and biochemical alteration of the blood brain barrier (BBB) by the tumor microenvironment suggests immune cell trafficking in and out of the CNS is possible. Emerging clinical data suggest immune checkpoint inhibitors (ICIs) can stimulate T cells peripherally to in turn have anti-tumor effects in the CNS. For example, anti-programmed cell death-1 (PD-1) monotherapy with pembrolizumab has shown intracranial response rates of 20-30% in patients with melanoma or non-small cell lung cancer (NSCLC) brain metastases. The combination of nivolumab and ipilimumab [anti-PD-1 and anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4)] showed an intracranial response rate of 55% in patients with melanoma brain metastases. More data are needed to confirm these response rates and to determine mechanisms of efficacy and resistance. While local therapies such as stereotactic radiosurgery (SRS), whole-brain radiation therapy (WBRT), and surgery remain current mainstays, ICIS offer potential decreased neurotoxicity. This review summarizes the biological rationale for systemic immunotherapy to treat CNS metastatic disease, existing clinical data on ICIs in this setting and ongoing clinical trials exploring areas of unmet need.

The role of radiation therapy in the treatment of metastatic cancer

Radiation therapy continues to play an important role in the management of cancer. In this review, we discuss the use of radiation therapy to target and control micrometastatic disease (adjuvant use of radiation), or using stereotactic radiation therapy to address small volumes of gross disease, such as oligometastases, and finally the use of radiation therapy in the era of immunotherapy. Radiation therapy is commonly used to treat nodal basins suspected of harboring microscopic disease. More recently, computer and technical innovations have allowed radiation oncologists to treat small volumes of gross disease within the brain and also in the body with great success, adding to the cancer armamentarium. This modality of cancer treatment that began shortly after the discovery of X-rays by William Roentgen continues to evolve and finds new clinical applications which minimize toxicity while increasing effectiveness. The newly discovered interactions of high dose/fraction radiation (stereotactic radiosurgery) with immune check point inhibitors in melanoma is the latest example of how synergism can be achieved between two different modalities thus increasing the therapeutic ratio to control metastatic cancer.

Stereotactic Radiosurgery in the Management of Patients With Brain Metastases of Non-Small Cell Lung Cancer: Indications, Decision Tools and Future Directions

Brain metastases (BM) frequently occur in non-small cell lung cancer (NSCLC) patients. Most patients with BM have a limited life expectancy, measured in months. Selected patients may experience a very long progression-free survival, for example, patients with a targetable driver mutation. Traditionally, whole-brain radiotherapy (WBRT) has been the cornerstone of the treatment, but its indication is a matter of debate. A randomized trial has shown that for patients with a poor prognosis, WBRT does not add quality of life (QoL) nor survival over the best supportive care. In recent decades, stereotactic radiosurgery (SRS) has become an attractive non-invasive treatment for patients with BM. Only the BM is irradiated to an ablative dose, sparing healthy brain tissue. Intracranial recurrence rates decrease when WBRT is administered following SRS or resection but does not improve overall survival and comes at the expense of neurocognitive function and QoL. The downside of SRS compared with WBRT is a risk of radionecrosis (RN) and a higher risk of developing new BM during follow-up. Currently, SRS is an established treatment for patients with a maximum of four BM. Several promising strategies are currently being investigated to further improve the indication and outcome of SRS for patients with BM: the effectivity and safety of SRS in patients with more than four BM, combining SRS with systemic therapy such as targeted agents or immunotherapy, shared decision-making with SRS as a treatment option, and individualized isotoxic dose prescription to mitigate the risk of RN and further enhance local control probability of SRS. This review discusses the current indications of SRS and future directions of treatment for patients with BM of NSCLC with focus on the value of SRS.

Complete intracranial response to talimogene laherparepvec (T-Vec), pembrolizumab and whole brain radiotherapy in a patient with melanoma brain metastases refractory to dual checkpoint-inhibition

Background

Immunotherapy, in particular checkpoint blockade, has changed the clinical landscape of metastatic melanoma. Nonetheless, the majority of patients will either be primary refractory or progress over follow up. Management of patients progressing on first-line immunotherapy remains challenging. Expanded treatment options with combination immunotherapy has demonstrated efficacy in patients previously unresponsive to single agent or alternative combination therapy.

Case presentation

We describe the case of a patient with diffusely metastatic melanoma, including brain metastases, who, despite being treated with stereotactic radiosurgery and dual CTLA-4/PD-1 blockade (ipilimumab/nivolumab), developed systemic disease progression and innumerable brain metastases. This patient achieved a complete CNS response and partial systemic response with standard whole brain radiation therapy (WBRT) combined with Talimogene laherparepvec (T-Vec) and pembrolizumab.

Conclusion

Patients who do not respond to one immunotherapy combination may respond during treatment with an alternate combination, even in the presence of multiple brain metastases. Biomarkers are needed to assist clinicians in evidence based clinical decision making after progression on first line immunotherapy to determine whether response can be achieved with second line immunotherapy.

Immune checkpoint inhibitors: new strategies to checkmate cancer

Immune checkpoint inhibitors (ICIs) targeting cytotoxic T lymphocyte-associated protein-4 (CTLA-4) or programmed cell death protein 1 (PD-1) receptors have demonstrated remarkable efficacy in subsets of patients with malignant disease. This emerging treatment modality holds great promise for future cancer treatment and has engaged pharmaceutical research interests in tumour immunology. While ICIs can induce rapid and durable responses in some patients, identifying predictive factors for effective clinical responses has proved challenging. This review summarizes the mechanisms of action of ICIs and outlines important preclinical work that contributed to their development. We explore clinical data that has led to disease-specific drug licensing, and highlight key clinical trials that have revealed ICI efficacy across a range of malignancies. We describe how ICIs have been used as part of combination therapies, and explore their future prospects in this area. We conclude by discussing the incorporation of these new immunotherapeutics into precision approaches to cancer therapy.