Possible Interaction of Anti-PD-1 Therapy with the Effects of Radiosurgery on Brain Metastases

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.

Stereotactic radiosurgery with immune checkpoint inhibitors for brain metastases: a meta-analysis study

BACKGROUND

Immune checkpoint inhibitors (ICIs) are an emerging tool in the treatment of brain metastases (BMs), Stereotactic radiosurgery (SRS), traditionally used for BMs, elicits an immune brain response and can act synergistically with ICIs. We aim to investigate the efficacy of ICI administered with SRS and determine the impact of timing on BM response.

METHODS

A systematical search was performed to identify potential studies concerning BMs managed with SRS alone or with SRS + ICI with relative timing administration (ICI concurrent with SRS, ICI nonconcurrent with SRS, SRS before ICI, SRS after ICI). The overall survival (OS), 12-month OS, local progression-free survival (LPFS), 12-month local brain control (LBC), distant progression-free survival (DPFS), 12-month distant brain control (DBC), and adverse events (intracranial hemorrhage, radionecrosis) were analyzed using the random-effects model.

RESULTS

A total of 16 retrospective studies with 1356 BM patients were included. Compared to nonconcurrent therapy, concurrent therapy revealed a significantly longer OS (HR= 1.43; p = 0.008) and 12-months LBC (HR = 1.91; p = 0.04), a similar 12-months DBC (HR = 1.12; p = 0.547) and higher complication rate (R = 0.77; p = 0.346). Concurrent therapy leads to a significantly higher OS compared to ICI before SRS (HR = 2.55; p = 0.0003).

CONCLUSION

The combination of SRS with ICI improves patients' clinical and radiological outcomes. The effectiveness of the combination is subject to the identification of an optimal therapeutic window.

Whole brain radiation therapy resulting in radionecrosis: a possible link with radiosensitising chemoimmunotherapy

Radionecrosis describes a rare but serious complication of radiation therapy. In clinical practice, stereotactic radiosurgery (SRS) is increasingly used in combination with systemic therapy, including chemotherapy, immune checkpoint inhibitor and targeted therapy, either concurrently or sequentially. There is a paucity of literature regarding radionecrosis in patients receiving whole brain radiation therapy (WBRT) alone (without additional SRS) in combination with immunotherapy or targeted therapies. It is observed that certain combinations increase the overall radiosensitivity of the tumorous lesions. We present a rare case of symptomatic radionecrosis almost 1 year after WBRT in a patient with non-squamous non-small cell lung cancer on third-line chemoimmunotherapy. We discuss available research regarding factors that may lead to radionecrosis in these patients, including molecular and genetic profiles, specific drug therapy combinations and their timing or increased overall survival.

Optimal timing and sequence of combining stereotactic radiosurgery with immune checkpoint inhibitors in treating brain metastases: clinical evidence and mechanistic basis

Recent evidence has shown that immune checkpoint inhibitors (ICIs) are efficacious for treating brain metastases of various primary tumors. However, the immunosuppressive tumor microenvironment and the blood-brain barrier (BBB) or blood-tumor barrier (BTB) essentially restrict the efficacy of ICIs. Stereotactic radiosurgery (SRS) can be a powerful ally to ICIs due to its trait of disrupting the BBB/BTB and increasing the immunogenicity of brain metastases. The combination of SRS + ICI has shown synergy in brain metastases in several retrospective studies. Nevertheless, the optimal schedule for the combination of SRS and ICI in brain metastases is yet to be determined. In this review, we summarized the current clinical and preclinical evidence on the timing and sequence of SRS + ICI to provide insight into the current state of knowledge about this important area in patient care.

The progress of microenvironment-targeted therapies in brain metastases

The incidence of brain metastases (BrM) has become a growing concern recently. It is a common and often fatal manifestation in the brain during the end-stage of many extracranial primary tumors. Increasing BrM diagnoses can be attributed to improvements in primary tumor treatments, which have extended patients’ lifetime, and allowed for earlier and more efficient detection of brain lesions. Currently, therapies for BrM encompass systemic chemotherapy, targeted therapy, and immunotherapy. Systemic chemotherapy regimens are controversial due to their associated side effects and limited efficacy. Targeted and immunotherapies have garnered significant attention in the medical field: they target specific molecular sites and modulate specific cellular components. However, multiple difficulties such as drug resistance and low permeability of the blood-brain barrier (BBB) remain significant challenges. Thus, there is an urgent need for novel therapies. Brain microenvironments consist of cellular components including immune cells, neurons, endothelial cells as well as molecular components like metal ions, nutrient molecules. Recent research indicates that malignant tumor cells can manipulate the brain microenvironment to change the anti-tumoral to a pro-tumoral microenvironment, both before, during, and after BrM. This review compares the characteristics of the brain microenvironment in BrM with those in other sites or primary tumors. Furthermore, it evaluates the preclinical and clinical studies of microenvironment-targeted therapies for BrM. These therapies, due to their diversity, are expected to overcome drug resistance or low permeability of the BBB with low side effects and high specificity. This will ultimately lead to improved outcomes for patients with secondary brain tumors.

Lung cancer with brain metastases remaining in continuous complete remission due to pembrolizumab and temozolomide: a case report

Background

Immunotherapy has been shown to improve the overall survival (OS) in patients with advanced or metastatic non-small cell lung cancer (NSCLC) without driver gene mutations. However, monotherapy with immunotherapy alone or combined with chemotherapy in NSCLC patients with untreated brain metastases (BM) is still under debate. Data regarding treatment of BM with immunotherapy and temozolomide (TMZ) in patients with NSCLC is rare.

Case Presentation

A 60-year-old male due to cough and expectoration presented in our hospital. Chest computed tomography (CT), brain magnetic resonance imaging (MRI) and immunohistochemistry of a mediastinal lymph node biopsy were administered, he was diagnosed with stage IIIB lung adenocarcinoma. Without driver gene mutations, he was treated with platinum-based chemotherapy because he refused to accept concurrent radiation therapy (RT). Heavy cough companied with hemoptysis and chest CT scan both revealed progressive disease (PD) after 6 cycles of chemotherapy. Immunotherapy was consequently considered, while two metastatic lesions in the brain were confirmed after combined treatment of pembrolizumab with docetaxel. TMZ was administered in combination with pembrolizumab (200 mg, day 1). A new metastasis in the right occipital lobe was detected on a scan 1 month later, though the other 2 lesions continued to shrink. The treatment was continued, MRI and CT scans suggested complete response (CR) was achieved for both the BM and lung lesions after 3 cycles. Consolidation therapy with TMZ and pembrolizumab (100 mg) per month was considered for another 7 months. Maintenance monotherapy with pembrolizumab (100 mg) was selected because of his stable CR status. At 59 months since diagnosis, the patient remains alive, with CR for both the primary lesions and BM. The patient experienced slight numbness on each side of his feet. There was no occurrence of adverse effects greater than grade 3.

Conclusions

The data indicates that immunotherapy combined with TMZ for untreated BM in NSCLC patients maybe an efficient and safe decision making therapeutic choice. Despite the encouraging efficacy of the combination, it is an isolated case and the speculation of synergism need to be proved in further pharmacokinetic/pharmacodynamic studies even in large randomized controlled trials.

Histological changes associated with laser interstitial thermal therapy for radiation necrosis: illustrative cases

BACKGROUND

Patients with lung cancer and melanoma remain the two largest groups to develop brain metastases. Immunotherapy has been approved for treatment of stage IV disease in both groups. Many of these patients are additionally treated with stereotactic radiosurgery for their brain metastases during ongoing immunotherapy. Use of immunotherapy has been reported to increase the rates of radiation necrosis (RN) after radiosurgery, causing neurological compromise due to growth of the enhancing lesion as well as worsening of associated cerebral edema.

OBSERVATIONS

Laser interstitial thermal therapy (LITT) is a surgical approach that has been shown effective in the management of RN, especially given its efficacy in early reduction of perilesional edema. However, little remains known about the pathology of the post-LITT lesions and how LITT works in this condition. Here, we present two patients who needed surgical decompression after LITT for RN. Clinical, histopathological, and imaging features of both patients are presented.

LESSONS

Criteria for selecting the best patients with RN for LITT therapy remains unclear. Given two similarly sized lesions and not too dissimilar clinical histories but with differing outcomes, further investigation is clearly needed to identify predictors of response to LITT in the setting of SRS and immunotherapy-induced RN.

Immune-related aseptic meningitis and strategies to manage immune checkpoint inhibitor therapy: a systematic review

INTRODUCTION

Immune checkpoint inhibitors (ICIs) can induce adverse neurological effects. Due to its rarity as an adverse effect, meningitis has been poorly described. Therefore, meningitis diagnosis and management can be challenging for specialists. Moreover, meningitis can be an obstacle to resuming immunotherapy. Given the lack of alternatives, the possibility of reintroducing immunotherapy should be discussed on an individual basis. Here, we present a comprehensive systematic review of meningitis related to ICIs.

REVIEW

We performed a search for articles regarding immune-related meningitis published in PubMed up to November 2021 with the MeSH terms "meningitis" and "immune checkpoint" using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method. We summarized the studies not only by category but also based on whether it was a primary article or case report to provide a systematic overview of the subject. We reviewed a total of 38 studies and herein report the clinical experiences, pharmacovigilance data and group knowledge from these studies.

CONCLUSION

This review summarizes the existing information on immune-related meningitis and the possibility of reintroducing immunotherapy after the development of central neurological side effects. To the best of our knowledge, there is little information in the literature to guide clinicians on decisions regarding whether immunotherapy should be continued after a neurological adverse event occurs, especially meningeal events. This review emphasizes the necessity of systematic examinations, steroid treatment (as a cornerstone of management) and the need for further exploratory studies to obtain a clearer understanding of how to better manage patients who experience these side effects. The findings summarized in this review can help provide guidance to practitioners who face this clinical situation.

Neuroinflammatory changes of the normal brain tissue in cured mice following combined radiation and anti-PD-1 blockade therapy for glioma

The efficacy of combining radiation therapy with immune checkpoint inhibitor blockade to treat brain tumors is currently the subject of multiple investigations and holds significant therapeutic promise. However, the long-term effects of this combination therapy on the normal brain tissue are unknown. Here, we examined mice that were intracranially implanted with murine glioma cell line and became long-term survivors after treatment with a combination of 10 Gy cranial irradiation (RT) and anti-PD-1 checkpoint blockade (aPD-1). Post-mortem analysis of the cerebral hemisphere contralateral to tumor implantation showed complete abolishment of hippocampal neurogenesis, but neural stem cells were well preserved in subventricular zone. In addition, we observed a drastic reduction in the number of mature oligodendrocytes in the subcortical white matter. Importantly, this observation was evident specifically in the combined (RT + aPD-1) treatment group but not in the single treatment arm of either RT alone or aPD-1 alone. Elimination of microglia with a small molecule inhibitor of colony stimulated factor-1 receptor (PLX5622) prevented the loss of mature oligodendrocytes. These results identify for the first time a unique pattern of normal tissue changes in the brain secondary to combination treatment with radiotherapy and immunotherapy. The results also suggest a role for microglia as key mediators of the adverse treatment effect.

Imaging of Response to Radiosurgery and Immunotherapy in Brain Metastases: Quo Vadis?

Purpose of Review

This review presents an overview of how advanced imaging techniques may help to overcome shortcomings of anatomical MRI for response assessment in patients with brain metastases who are undergoing stereotactic radiosurgery, immunotherapy, or combinations thereof.

Recent Findings

Study results suggest that parameters derived from amino acid PET, diffusion- and perfusion-weighted MRI, MR spectroscopy, and newer MRI methods are particularly helpful for the evaluation of the response to radiosurgery or checkpoint inhibitor immunotherapy and provide valuable information for the differentiation of radiotherapy-induced changes such as radiation necrosis from brain metastases. The evaluation of these imaging modalities is also of great interest in the light of emerging high-throughput analysis methods such as radiomics, which allow the acquisition of additional data at a low cost.

Summary

Preliminary results are promising and should be further evaluated. Shortcomings are different levels of PET and MRI standardization, the number of patients enrolled in studies, and the monocentric and retrospective character of most studies.

Nanomaterials for Protein Delivery in Anticancer Applications

Nanotechnology platforms, such as nanoparticles, liposomes, dendrimers, and micelles have been studied extensively for various drug deliveries, to treat or prevent diseases by modulating physiological or pathological processes. The delivery drug molecules range from traditional small molecules to recently developed biologics, such as proteins, peptides, and nucleic acids. Among them, proteins have shown a series of advantages and potential in various therapeutic applications, such as introducing therapeutic proteins due to genetic defects, or used as nanocarriers for anticancer agents to decelerate tumor growth or control metastasis. This review discusses the existing nanoparticle delivery systems, introducing design strategies, advantages of using each system, and possible limitations. Moreover, we will examine the intracellular delivery of different protein therapeutics, such as antibodies, antigens, and gene editing proteins into the host cells to achieve anticancer effects and cancer vaccines. Finally, we explore the current applications of protein delivery in anticancer treatments.

Immune checkpoint inhibitor therapy may increase the incidence of treatment-related necrosis after stereotactic radiosurgery for brain metastases: a systematic review and meta-analysis

OBJECTIVES

To compare the incidence of treatment-related necrosis between combination SRS+ICI therapy and SRS therapy alone in patients with brain metastases from melanoma and non-small cell lung cancer (NSCLC).

METHODS

A systematic literature search of Ovid-MEDLINE and EMBASE was performed up to August 10, 2020. The difference in the pooled incidence of treatment-related necrosis after SRS+ICI or SRS alone was evaluated. The cumulative incidence of treatment-related necrosis at the specific time point after the treatment was calculated and plotted. Subgroup and meta-regression analyses were additionally performed.

RESULTS

Sixteen studies (14 on melanoma, 2 on NSCLC) were included. In NSCLC brain metastasis, the reported incidences of treatment-related necrosis in SRS+ICI and SRS alone ranged 2.9-3.4% and 0-2.9%, respectively. Meta-analysis was conducted including 14 studies on melanoma brain metastasis. The incidence of treatment-related necrosis was higher in SRS+ICI than SRS alone (16.0% vs. 6.5%; p = 0.065; OR, 2.35). The incidence showed rapid increase until 12 months after the SRS when combined with ICI therapy (14%; 95% CI, 8-22%) and its pace of increase slowed thereafter. Histopathologic diagnosis as the reference standard for treatment-related necrosis and inclusion of only symptomatic cases were the source of heterogeneity in SRS+ICI.

CONCLUSIONS

Treatment-related necrosis tended to occur 2.4 times more frequently in the setting of combination SRS+ICI therapy compared with SRS alone in melanoma brain metastasis showing high cumulative incidence within the first year. Treatment-related necrosis should be considered when SRS+ICI combination therapy is used for melanoma brain metastasis, especially in the first year.

KEY POINTS

• Treatment-related necrosis occurred 2.4 times more frequently in the setting of combination SRS+ICI therapy compared with SRS alone in melanoma brain metastasis. • Treatment-related necrosis more frequently occurred in brain metastases from melanoma than NSCLC. • Reference standard for treatment-related necrosis and inclusion of only symptomatic treatment-related necrosis were a significant source of heterogeneity, indicating varying definitions of treatment-related necrosis in the literature need to be unified.

Tumor-Specific Antibody, Cetuximab, Enhances the In Situ Vaccine Effect of Radiation in Immunologically Cold Head and Neck Squamous Cell Carcinoma

In head and neck squamous cell carcinoma (HNSCC) tumors that over-expresses huEGFR, the anti-EGFR antibody, cetuximab, antagonizes tumor cell viability and sensitizes to radiation therapy. However, the immunologic interactions between cetuximab and radiation therapy are not well understood. We transduced two syngeneic murine HNSCC tumor cell lines to express human EGFR (MOC1- and MOC2-huEGFR) in order to facilitate evaluation of the immunologic interactions between radiation and cetuximab. Cetuximab was capable of inducing antibody-dependent cellular cytotoxicity (ADCC) in MOC1- and MOC2-huEGFR cells but showed no effect on the viability or radiosensitivity of these tumor cells, which also express muEGFR that is not targeted by cetuximab. Radiation enhanced the susceptibility of MOC1- and MOC2-huEGFR to ADCC, eliciting a type I interferon response and increasing expression of NKG2D ligands on these tumor cells. Co-culture of splenocytes with cetuximab and MOC2-huEGFR cells resulted in increased expression of IFNγ in not only NK cells but also in CD8+ T cells, and this was dependent upon splenocyte expression of FcγR. In MOC2-huEGFR tumors, combining radiation and cetuximab induced tumor growth delay that required NK cells, EGFR expression, and FcγR on host immune cells. Combination of radiation and cetuximab increased tumor infiltration with NK and CD8+ T cells but not regulatory T cells. Expression of PD-L1 was increased in MOC2-huEGFR tumors following treatment with radiation and cetuximab. Delivering anti-PD-L1 antibody with radiation and cetuximab improved survival and resulted in durable tumor regression in some mice. Notably, these cured mice showed evidence of an adaptive memory response that was not specifically directed against huEGFR. These findings suggest an opportunity to improve the treatment of HNSCC by combining radiation and cetuximab to engage an innate anti-tumor immune response that may prime an effective adaptive immune response when combined with immune checkpoint blockade. It is possible that this approach could be extended to any immunologically cold tumor that does not respond to immune checkpoint blockade alone and for which a tumor-specific antibody exists or could be developed.

Enhanced tumor response to radiotherapy after PD-1 blockade in metastatic gastric cancer

BACKGROUND

Immune checkpoint inhibitors may enhance the efficacy of radiotherapy (RT) in cancer treatment but the effect remains unknown in metastatic gastric cancer (mGC). This study aimed to compare the tumor shrinkage by palliative RT for mGC patients with or without previous exposure to anti-PD-1 therapy.

METHODS

Data of 36 mGC patients who had received palliative RT from April 2013 to May 2019 were analyzed. Primary tumor responses were evaluated through a volumetric measurement-based method using computed tomography (CT) and endoscopic responses were evaluated in patients who underwent endoscopy before and after RT. Tumor microenvironment (TME) immune status was investigated by analyzing tumor-infiltrating lymphocytes by flow cytometry.

RESULTS

Among 36 patients, 18 had previous exposure to anti-PD-1 before RT showing no significant differences in baseline characteristics with the other 18 patients without exposure to anti-PD-1 treatment. Tumor responses were observed in 28% (5/18) and none (0/18) in the anti-PD-1-exposed vs. naïve group, respectively (P = 0.045). Five out of eight patients in the anti-PD-1-exposed group, who underwent endoscopy after RT showed partial response, but none in the anti-PD-1-naïve patients showed response (P = 0.026). Increase in the CD8⁺ T cell/effector regulatory T cell ratio in TILs after anti-PD-1 therapy was noted in three responders to RT, but not in the other three non-responders.

CONCLUSIONS

Prior exposure to anti-PD-1 therapy increases tumor response to RT. Immune profiling suggests that anti-PD-1 therapy may enhance the efficacy of RT by immunoactivation in the TME.

Melanoma brain metastases - Interdisciplinary management recommendations 2020

Melanoma brain metastases (MBM) are common and associated with a particularly poor prognosis; they directly cause death in 60-70% of melanoma patients. In the past, systemic treatments have shown response rates around 5%, whole brain radiation as standard of care has achieved a median overall survival of approximately three months. Recently, the combination of immune checkpoint inhibitors and combinations of MAP-kinase inhibitors both have shown very promising response rates of up to 55% and 58%, respectively, and improved survival. However, current clinical evidence is based on multi-cohort studies only, as prospectively randomized trials have been carried out rarely in MBM, independently whether investigating systemic therapy, radiotherapy or surgical techniques. Here, an interdisciplinary expert team reviewed the outcome of prospectively conducted clinical studies in MBM, identified evidence gaps and provided recommendations for the diagnosis, treatment, outcome evaluation and monitoring of MBM patients. The recommendations refer to four distinct scenarios: patients (i) with 'brain-only' disease, (ii) with oligometastatic asymptomatic intra- and extracranial disease, (iii) with multiple asymptomatic metastases, and (iv) with multiple symptomatic MBM or leptomeningeal disease. Changes in current management recommendations comprise the use of immunotherapy - preferably combined anti-CTLA-4/PD-1-immunotherapy - in asymptomatic MBM minus/plus stereotactic radiosurgery which remains the mainstay of local brain therapy being safe and effective. Adjuvant whole-brain radiotherapy provides no clinical benefit in oligometastatic MBM. Among the systemic therapies, combined MAPK-kinase inhibition provides, in BRAF^V600-mutated patients with rapidly progressing or/and symptomatic MBM, an alternative to combined immunotherapy.

PD-1/PD-L1 Blockers in NSCLC Brain Metastases: Challenging Paradigms and Clinical Practice

Immune checkpoint inhibitors (ICI) have revolutionized the management of advanced non-small cell lung cancer (NSCLC). However, most pivotal phase III trials systematically excluded patients with active brain metastases, precluding the generalization of the results. Although theoretically restricted from crossing the blood-brain barrier, the novel pharmacokinetic/pharmacodynamic profiles of anti-PD-1/PD-L1 drugs have prompted studies to evaluate their activity in patients with NSCLC with active central nervous system (CNS) involvement. Encouraging results have suggested that ICI could be active in the CNS in selected patients with driver-negative advanced NSCLC with high PD-L1 expression and low CNS disease burden. Single-agent CNS response rates around 30% have been reported. Beyond this particular setting, anti-PD-1/PD-L1 antibodies have been evaluated in patients receiving local therapy for brain metastases (BM), addressing concerns about potential neurologic toxicity risks associated with radiotherapy, more specifically, radionecrosis (RN). Accordingly, a variety of clinical and imaging strategies are being appropriately developed to evaluate tumor response and to rule out pseudoprogression or radionecrosis. Our purpose is to critically summarize the advances regarding the role of systemic anti-PD-1/PD-L1 antibodies for the treatment of NSCLC BM. Data were collected from the PubMed database, reference lists, and abstracts from the latest scientific meetings. Recent reports suggest anti-PD-1/PD-L1 agents are active in a subset of patients with NSCLC with BM showing acceptable toxicity. These advances are expected to change soon the management of these patients but additional research is required to address concerns regarding radionecrosis and the appropriate sequencing of local and systemic therapy combinations.

The emerging role of epigenetic therapeutics in immuno-oncology

The past decade has seen the emergence of immunotherapy as a prime approach to cancer treatment, revolutionizing the management of many types of cancer. Despite the promise of immunotherapy, most patients do not have a response or become resistant to treatment. Thus, identifying combinations that potentiate current immunotherapeutic approaches will be crucial. The combination of immune-checkpoint inhibition with epigenetic therapy is one such strategy that is being tested in clinical trials, encompassing a variety of cancer types. Studies have revealed key roles of epigenetic processes in regulating immune cell function and mediating antitumour immunity. These interactions make combined epigenetic therapy and immunotherapy an attractive approach to circumvent the limitations of immunotherapy alone. In this Review, we highlight the basic dynamic mechanisms underlying the synergy between immunotherapy and epigenetic therapies and detail current efforts to translate this knowledge into clinical benefit for patients.

Immune profiling reveals the diverse nature of the immune response in NSCLC and reveals signaling pathways that may influence the anti-tumor immune response

Recent FDA approvals of immunotherapy for NSCLC provide patients new treatment options, and these approvals also highlight the importance of the immune response in cancer treatment. While immunotherapy provides patients a new treatment option, the therapy is effective in less than half of the treated patients. To attain greater insight into the tumor-immune microenvironment, NSCLC tumors were analyzed by IHC and RNA-seq. IHC was used to identify NSCLC tumors that contain low, moderate, or high levels of CD8+ positive cells as a manifestation of an active anti-tumor immune response. Gene expression analysis identified an emergent gene signature that is associated with high and moderate levels of CD8 in NSCLC. In addition, the NSCLC tumors also express a unique combination of genes that may indicate complex anti-tumor immune responses (INFG-related genes, STATs, CXCL9, OX40, PD-L1, PD-L2, IDO1, and CD47). Several NSCLC tumors also express the immune checkpoint PD-L1 and at least one additional immune inhibitory molecule (IDO1, PD-L2, or others), which may explain the lack of a therapeutic response to treatments that disrupt only one immune checkpoint pathway.

Nivolumab and stereotactic radiation therapy for the treatment of patients with Stage IV non-small-cell lung cancer

Background

Radiation therapy might modify the cancer immune environment to enhance the antitumor effect of immune checkpoint inhibitors. We performed a feasibility study of nivolumab following stereotactic radiation therapy for chemotherapy pretreated advanced non-small-cell lung cancer.

Patients and methods

Pretreated advanced/recurrent non-small-cell lung cancer patients received stereotactic radiation therapy to one of the disease sites. Nivolumab at a dose of 3 mg/kg was given within 2 weeks after the completion of stereotactic radiation therapy and continued every 2 weeks thereafter until disease progression or unacceptable toxicities. The primary endpoint was the occurrence rate of Grade 3 pneumonitis (within 12 weeks) or other non-hematological toxicity (within 8 weeks).

Results

From September 2016 to September 2017, six patients were enrolled. Five received stereotactic radiation therapy to their primary lesions. All patients received nivolumab on the following day after stereotactic radiation therapy completion. Grade 3 pneumonitis occurred in one patient, but no other serious adverse events were reported for the other patients. One complete response and two partial responses were achieved. Four patients had measurable lesions outside the irradiated area, of whom three patients responded to the treatment. The initial progression sites were mainly outside the irradiated field, including one brain metastasis.

Conclusions

Nivolumab therapy immediately following stereotactic radiation therapy was well tolerated. This sequential combination warrants further study.

Long-Term Survival of Patients With Melanoma With Active Brain Metastases Treated With Pembrolizumab on a Phase II Trial

PURPOSE

Pembrolizumab is active in melanoma, but activity in patients with untreated brain metastasis is less established. We present long-term follow-up of pembrolizumab-treated patients with new or progressing brain metastases treated on a phase II clinical trial ( ClinicalTrials.gov identifier: NCT02085070).

PATIENTS AND METHODS

We enrolled 23 patients with melanoma with one or more asymptomatic, untreated 5- to 20-mm brain metastasis not requiring corticosteroids; 70% of patients had prior systemic therapy. Pembrolizumab was administered for up to 24 months. Brain metastasis response, the primary end point, was assessed by modified Response Evaluation Criteria in Solid Tumors (RECIST). Pretreatment tumors were analyzed for T-cell infiltrate and programmed death ligand 1.

RESULTS

Six patients (26%) had a brain metastasis response. Eight patients (35%) did not reach a protocol evaluation scan and were unevaluable for brain metastasis response as a result of progression or need for radiation. Brain metastasis and systemic responses were concordant, with all ongoing at 24 months. The median progression-free and overall survival times were 2 and 17 months, respectively. Eleven patients (48%) were alive at 24 months. This included three unevaluable patients. One of these three patients had hemorrhaged, and two had symptoms from perilesional edema requiring radiosurgery, but all three patients remained on commercial pembrolizumab more than 24 months later. None of the 24-month survivors received subsequent BRAF inhibitors. Neurologic adverse events occurred in 65% of patients; all adverse events but one were grade 1 or 2. Three patients had seizures, which were treated with anticonvulsants. Most responders had higher pretreatment tumor CD8 cell density and programmed death ligand 1 expression, whereas all nonresponders did not.

CONCLUSION

Pembrolizumab is active in melanoma brain metastases with acceptable toxicity and durable responses. Multidisciplinary care is required to optimally manage patients with brain metastases, including consideration of radiation to large or symptomatic lesions, which were excluded in this trial. Two-year survival was similar to patients without brain metastasis treated with anti-programmed cell death 1 agents. Concordant brain and extracerebral responses support use of pembrolizumab to treat small, asymptomatic brain metastases.

Toxicity of radiation and immunotherapy combinations

Purpose

Although immunotherapy is a rapidly emerging modality for cancer care, there have been multiple reports of fatal toxicities. There have also been cases of treatment-related deaths with combined non-immunotherapeutic biologic compounds with radiation therapy. Thus, provision of summative information appraising the safety of combinatorial immunotherapy and radiation therapy (iRT) is imperative. Because this has not been well characterized, this review summarizes the available evidence to date.

Methods and materials

Owing to the heterogeneity and relatively low quantity of published reports, this review was conducted in a narrative rather than systematic format.

Results

The results of combined iRT, both concurrent and sequential, are discussed for oncologic therapy of the brain, lung, liver, and prostate. Most evidence is from small samples and shorter follow-up but does consist of multiple prospective publications. Most data exist for ipilimumab, with programmed cell death -1 inhibitors emerging in more recent years. With 2 large phase 3 trials as exceptions, there were no instances of iRT-related deaths across all discussed studies. Altogether, grade 3 to 4 toxicities were relatively low in frequency; of the studies that compared iRT with an “immunotherapy only” or “RT only” cohort, none documented a clear increase in high-grade adverse events with combined-modality management.

Conclusions

Despite the low quantity of data, combined iRT offers encouraging safety profiles. There is no evidence that iRT produces an overt increase in high-grade toxicities. Further data, especially on concurrent iRT, are anticipated from numerous iRT trials that are currently ongoing worldwide.

Vaccine-Based Immunotherapeutics for the Treatment of Glioblastoma: Advances, Challenges, and Future Perspectives

Glioblastoma is a highly aggressive neoplasm with an extremely poor prognosis. Despite maximal gross resection and chemoradiotherapy, these grade IV astrocytomas consistently recur. Glioblastoma cells exhibit numerous pathogenic mechanisms to decrease tumor immunogenicity while promoting gliomagenesis, which manifests clinically as a median survival of less than 2 years and few long-term survivors. Recent clinical trials of vaccine-based immunotherapeutics against glioblastoma have demonstrated encouraging results in prolonging progression-free survival and overall survival. Several vaccine-based treatments have been trialed, such as peptide and heat-shock proteins, dendritic cell-based vaccines, and viral-based immunotherapy. In this literature review, we discuss the immunobiology of glioblastoma, significant current and completed vaccine-based immunotherapy clinical trials, and broad clinical challenges and future directions of glioblastoma vaccine-based immunotherapeutics.

Adjuvant radiotherapy and outcomes of presumed hemorrhagic melanoma brain metastases without malignant cells

Background

Patients with melanoma can present with a hemorrhagic intracranial lesion. Upon resection, pathology reports may not detect any malignant cells. However, the hemorrhage may obscure their presence and so physicians may still decide whether adjuvant radiotherapy should be applied. Here, we report on the outcomes of a series of patients with melanoma with hemorrhagic brain lesions that returned with no tumor cells.

Methods

All melanoma patients who had craniotomies from 2008 to 2017 at a single institution for hemorrhagic brain lesions were identified through retrospective chart review. Those who had pathology reports with no malignant cells were analyzed. Recurrence at the former site of hemorrhage and resection was the primary outcome.

Results

Ten patients met inclusion criteria, and the median follow-up time was 8.5 (1.8-27.3) months. At the time of craniotomy, the median number of brain lesions was 3 (1-25). Two patients had prior craniotomies, eight had prior radiation, and six had prior immunotherapy to the lesion of interest. After surgery, one patient received stereotactic radiosurgery (SRS) to the resection bed. Only one patient developed subsequent melanoma at the resection site; this patient developed the lesion recurrence once and had not received postoperative SRS.

Conclusion

Although small foci of metastatic disease as a source of bleeding for some patients cannot be excluded, melanoma patients with a suspected hemorrhagic brain metastasis that shows no tumor cells on pathology may benefit from close observation. The local recurrence risk in such cases appears to be low, even without adjuvant radiation.

Brain Metastases

Brain metastases from solid tumors are associated with increased morbidity and mortality. Standard treatment is local therapy with surgery and/or radiation therapy although there is increasing interest in systemic therapies that can control both intracranial and extracranial disease. We review the most recent data for local therapy and systemic therapy options. Active areas of research within radiation oncology include hippocampal sparing whole brain radiation therapy and stereotactic approaches for patients with more than 4 brain metastases. Newer targeted therapies with better central nervous system penetration and immunotherapies have demonstrated promising results in clinical trials of patients with brain metastases.

Radiation therapy and PD-1/PD-L1 blockade: the clinical development of an evolving anticancer combination

Several inhibitors of programmed cell death-1 (PD-1) and programmed death ligand-1 (PD-L1) have been approved as a form of immunotherapy for multiple cancers. Ionizing radiation therapy (RT) has been shown to enhance the priming and effector phases of the antitumor T-cell response rendering it an attractive therapy to combine with PD-1/PD-L1 inhibitors. Preclinical data support the rational combination of the 2 modalities and has paved way for the clinical development of the combination across a spectrum of cancers. In this review, we highlight the preclinical and clinical development of combined RT and PD-1/PD-L1 blockade to date. In addition to a comprehensive evaluation of available safety and efficacy data, we discuss important points of consideration in clinical trial design for this promising combination.

Combined irradiation and targeted therapy or immune checkpoint blockade in brain metastases: toxicities and efficacy

Background

Targeted therapies (TT) and immune checkpoint inhibitors (ICI) are currently modifying the landscape of metastatic cancer management and are increasingly used over the course of many cancers treatment. They allow long-term survival with controlled extra-cerebral disease, contributing to the increasing incidence of brain metastases (BMs). Radiation therapy remains the cornerstone of BMs treatment (either whole brain irradiation or stereotactic radiosurgery), and investigating the safety profile of radiation therapy combined with TT or ICI is of high interest. Discontinuing an efficient systemic therapy, when BMs irradiation is considered, might allow systemic disease progression and, on the other hand, the mechanisms of action of these two therapeutic modalities might lead to unexpected toxicities and/or greater efficacy, when combined.

Patients and methods

We carried out a systematic literature review focusing on the safety profile and the efficacy of BMs radiation therapy combined with targeted agents or ICI, emphasizing on the role (if any) of the sequence of combination scheme (drug given before, during, and/or after radiation therapy).

Results

Whereas no relevant toxicity has been noticed with most of these drugs, the concomitant use of some other drugs with brain irradiation requires caution.

Conclusion

Most of available studies appear to advocate for TT or ICI combination with radiation therapy, without altering the clinical safety profiles, allowing the maintenance of systemic treatments when stereotactic radiation therapy is considered. Cognitive functions, health-related quality of life and radiation necrosis risk remain to be assessed. The results of prospective studies are awaited in order to complete and validate the above discussed retrospective data.

Improved Overall Survival and Locoregional Disease Control With Concurrent PD-1 Pathway Inhibitors and Stereotactic Radiosurgery for Lung Cancer Patients With Brain Metastases

PURPOSE

Despite the emerging role of programmed cell death-1 (PD-1) pathway inhibitors for patients with advanced lung cancer, a paucity of data are available on the activity of these agents among patients with brain metastases. We investigated the outcomes of PD-1 pathway inhibitors and stereotactic radiosurgery (SRS) for the treatment of patients with brain metastases from lung cancer.

METHODS AND MATERIALS

We retrospectively reviewed the medical records of non-small-cell lung cancer patients with brain metastases consecutively treated with PD-1 pathway inhibitors and SRS at our institution from 2012 to 2017. Overall survival (OS), distant brain failure (DBF), and local control (LC) were assessed using Kaplan-Meier estimates and Cox regression models.

RESULTS

We identified 37 patients treated with SRS to 85 lesions (90.6% intact and 9.4% resected) and a median total of 7 doses of PD-1 pathway inhibitors (83.8% nivolumab, 10.8% atezolizumab, 5.4% pembrolizumab). Most lesions were treated with 18 Gy in a single fraction (n = 61; 71.8%). Patients treated with concurrent SRS and PD-1 pathway inhibitors had longer OS and reduced rates of DBF compared with patients treated with SRS before or after PD-1 pathway inhibitor therapy (1-year OS, 87.3% vs 70.0% vs 0%, P = .008; 1-year DBF, 38.5% vs 65.8% vs 100%, P = .042). LC was favorable among lesions treated with SRS concurrent with or after PD-1 pathway inhibitor therapy compared with before PD-1 pathway inhibitor therapy (1-year LC, 100% vs 72.3%, P = .016). Three lesions transiently enlarged after SRS and then had partially or completely resolved on follow-up imaging. Four patients required steroids for SRS-associated toxicity. No patient experienced grade ≥ 4 toxicity.

CONCLUSIONS

Concurrent treatment with SRS and PD-1 pathway inhibitors was associated with favorable OS and locoregional disease control. This combination of therapy was well tolerated and merits further evaluation in larger cohorts in a prospective setting.

Combining Immunotherapy and Radiotherapy for Cancer Treatment: Current Challenges and Future Directions

Since the approval of anti-CTLA4 therapy (ipilimumab) for late-stage melanoma in 2011, the development of anticancer immunotherapy agents has thrived. The success of many immune-checkpoint inhibitors has drastically changed the landscape of cancer treatment. For some types of cancer, monotherapy for targeting immune checkpoint pathways has proven more effective than traditional therapies, and combining immunotherapy with current treatment strategies may yield even better outcomes. Numerous preclinical studies have suggested that combining immunotherapy with radiotherapy could be a promising strategy for synergistic enhancement of treatment efficacy. Radiation delivered to the tumor site affects both tumor cells and surrounding stromal cells. Radiation-induced cancer cell damage exposes tumor-specific antigens that make them visible to immune surveillance and promotes the priming and activation of cytotoxic T cells. Radiation-induced modulation of the tumor microenvironment may also facilitate the recruitment and infiltration of immune cells. This unique relationship is the rationale for combining radiation with immune checkpoint blockade. Enhanced tumor recognition and immune cell targeting with checkpoint blockade may unleash the immune system to eliminate the cancer cells. However, challenges remain to be addressed to maximize the efficacy of this promising combination. Here we summarize the mechanisms of radiation and immune system interaction, and we discuss current challenges in radiation and immune checkpoint blockade therapy and possible future approaches to boost this combination.

Targeted Therapy and Immunotherapy Response Assessment with F-18 Fluorothymidine Positron-Emission Tomography/Magnetic Resonance Imaging in Melanoma Brain Metastasis: A Pilot Study

INTRODUCTION

This pilot study aimed at exploring the utility of the proliferation tracer F-18 fluorothymidine (FLT) and positron-emission tomography (PET)/magnetic resonance imaging (MRI) (FLT-PET/MRI) for early treatment monitoring in patients with melanoma brain metastasis (MBM) who undergo targeted therapy or immunotherapy.

MATERIAL AND METHODS

Patients with newly diagnosed MBM underwent baseline and follow-up FLT-PET/MRI scans at 3-4 weeks of targeted therapy or immunotherapy. Up to six measurable brain lesions ≥1.0 cm per subject, as identified on T1-weighted post-gadolinium images, were included for quantitative analyses. The maximum SUV of each lesion was divided by the mean SUV of the pons to obtain the SUV ratio (SUVR).

RESULTS

Five enrolled subjects underwent the baseline FLT-PET/MRI study in which the MBM showed a median size of 1.7 cm (range 1.0-2.9) and increased metabolic activity with SUVR of 9.9 (range 3.2-18.4). However, only two subjects (cases #1 and #2) returned for a follow-up scan. At baseline, a total of 22 lesions were analyzed in all five subjects, which showed a median size of 1.7 cm (range 1.0-2.9) and median SUVR of 9.9 (range 3.2-18.4). At follow-up, case #1 was a 55-year-old man who received targeted BRAF inhibitor and MEK inhibitor therapy with dabrafenib and trametinib. Fused PET/MRI data of six measured lesions demonstrated a significant reduction in MBM proliferative activity (median -68%; range -38 to -77%) and size (median -23%; range -4 to -55%) at three weeks of therapy. Nevertheless, the subject eventually progressed and died 13 months after therapy initiation. Case #2 was a 36-year-old man who received immunotherapy with nivolumab and ipilimumab. The five measured MBM lesions showed a mixed response at both proliferative and morphologic imaging at 1-month follow-up. Some lesions demonstrated interval decrease while others interval increase in proliferative activity with a median -44% (range -77 to +68%). On MRI, the size change was +7% (range -64 to +50%). The therapy was switched to dabrafenib and trametinib, which led to a partial response. The patient is still alive 16 months following therapy initiation.

CONCLUSION

The five cases presented show the potential benefit of hybrid FLT-PET/MRI for the diagnosis of MBM and treatment monitoring of targeted therapy and immunotherapy. However, further studies are required to assess their complementary role in distinguishing true progression from pseudoprogression.

Safety of Combined PD-1 Pathway Inhibition and Intracranial Radiation Therapy in Non-Small Cell Lung Cancer

INTRODUCTION

Intracranial metastases are a common cause of morbidity and mortality in patients with advanced NSCLC, and are frequently managed with radiation therapy (RT). The safety of cranial RT in the setting of treatment with immune checkpoint inhibitors (ICIs) has not been established.

METHODS

We identified patients with advanced NSCLC with brain metastases who received cranial RT and were treated with or without programmed cell death 1/programmed death ligand 1 inhibitors between August 2013 and September 2016. RT-related adverse events (AEs) were retrospectively evaluated and analyzed according to ICI treatment status, cranial RT type, and timing of RT with respect to ICI.

RESULTS

Of 163 patients, 50 (31%) received ICIs, whereas 113 (69%) were ICI naive. Overall, 94 (58%), 28 (17%), and 101 (62%) patients received stereotactic radiosurgery, partial brain irradiation, and/or whole brain RT, respectively. Fifty percent of patients received more than one radiation course. We observed no significant difference in rates of all-grade AEs and grade 3 or higher AEs between the ICI-naive and ICI-treated patients across different cranial RT types (grade ≥3 AEs in 8% of ICI-naive patients versus in 9% of ICI-treated patients for stereotactic radiosurgery [p = 1.00] and in 8% of ICI-naive patients versus in 10% of ICI-treated patients for whole brain RT [p = 0.71]). Additionally, there was no difference in AE rates on the basis of timing of ICI administration with respect to RT.

CONCLUSIONS

Treatment with an ICI and cranial RT was not associated with a significant increase in RT-related AEs, suggesting that use of programmed cell death 1/programmed death ligand 1 inhibitors in patients receiving cranial RT may have an acceptable safety profile. Nonetheless, additional studies are needed to validate this approach.

A Retrospective Analysis of the Efficacy of Pembrolizumab in Melanoma Patients With Brain Metastasis

A total of 50% of patients with melanoma will develop brain metastasis (BM). Pembrolizumab was approved for treatment of metastatic melanoma on the basis of significant systemic antitumor activity. Because of low enrollment of patients with BM in pembrolizumab trials, efficacy against melanoma BM remains unknown. We reviewed records of 89 consecutive patients with melanoma treated with pembrolizumab at our institution between May 1, 2014 and October 31, 2015 to determine the time to progression. Thirty-six (40%) patients had BM before pembrolizumab. Twenty-six (72%) patients with BM had received prior treatment for BM. With median follow-up of 17.2 months, 54 patients (61%) developed progressive disease on pembrolizumab. Intracranial progression occurred in 19 patients (21%), 3 of whom did not have BM before treatment. Median time to progression at any site was 6 months for those without BM (n=53), 5 months for those with treated BM (n=26), and 1.2 months for patients with untreated BM (n=10). Using a Cox regression model adjusted for baseline factors, there was a statistically significant (Wald χ P=0.003) reduction in the hazard of progression for patients without BM [hazard ratio, 0.19; 90% confidence interval, 0.08-0.42) and patients with treated BM (hazard ratio, 0.27; 90% confidence interval, 0.12-0.64) compared with those with untreated BM. In conclusion, melanoma patients with pretreated BM can have durable systemic responses to pembrolizumab. Large, prospective studies are needed to evaluate the intracranial antitumor activity of pembrolizumab in melanoma patients with untreated BM.

Effect of Gamma Knife Radiosurgery and Programmed Cell Death 1 Receptor Antagonists on Metastatic Melanoma

Learning objectives

To evaluate radiation-induced changes in patients with brain metastasis secondary to malignant melanoma who received treatment with Gamma Knife radiosurgery (GKRS) and programmed cell death 1 (PD-1) receptor antagonists.

Introduction 

Stereotactic radiosurgery and chemotherapeutics are used together for treatment of metastatic melanoma and have been linked to delayed radiation-induced vasculitic leukoencephalopathy (DRIVL). There have been reports of more intense interactions with new immunotherapeutics targeting PD-1 receptors, but their interactions have not been well described and may result in an accelerated response to GKRS. Here we present data on subjects treated with this combination from a single institution.

Methods

Records from patients who underwent treatment for metastatic melanoma to the brain with GKRS from 2011 to 2016 were reviewed. Demographics, date of brain metastasis diagnosis, cause of death when applicable, immunotherapeutics, and imaging findings were recorded. The timing of radiation therapy and medications were also documented. 

Results

A total of 79 subjects were treated with GKRS, and 66 underwent treatment with both GKRS and immunotherapy. Regarding the 30 patients treated with anti-PD-1 immunotherapy, 21 patients received pembrolizumab, seven patients received nivolumab, and two patients received pembrolizumab and nivolumab. Serial imaging was available for interpretation in 25 patients, with 13 subjects who received GKRS and anti-PD-1 immunotherapy less than six weeks of each other. While four subjects had indeterminate/mixed findings on subsequent magnetic resonance imaging (MRI), nine subjects were noted to have progression. Two of these patients showed progression but subsequent imaging revealed a decrease in progression or improvement on MRI to previously targeted lesions by GKRS. None of the 13 subjects had surgery following their combined therapies.

Conclusions

This data suggests that there is need for further investigation of the role for concurrent treatment with PD-1 inhibitors and GKRS to enhance the treatment of metastatic melanoma. We present data on 13 patients who appear to have some radiologic benefit to this treatment combination, two of whom had radiographic pseudoprogression.

The Treatment of Melanoma Brain Metastases

Melanoma is the malignancy with the highest rate of dissemination to the central nervous system once it metastasizes. Until recently, the prognosis of patients with melanoma brain metastases (MBM) was poor. In recent years, however, the prognosis has improved due to high-resolution imaging that facilitates early detection of small asymptomatic brain metastases and early intervention with local modalities such as stereotactic radiosurgery. More recently, a number of systemic therapies have been approved by the Food and Drug Administration for metastatic melanoma, resulting in improved survival for many MBM patients. Registration trials for these newer therapies excluded patients with untreated brain metastases, and a number of studies specifically tailored to this population of patients have been conducted or are underway. Herein, we review contemporary locoregional and systemic therapies and describe the unique challenges posed by treatment of brain metastases, such as radionecrosis, cerebral edema, and pseudoprogression. Since the number of systemic and combined modality clinical trials has increased, we expect that the treatment landscape for patients with melanoma brain metastasis will change dramatically. In addition to ongoing clinical trials, which show great promise, we conclude that our understanding of intracranial metastasis remains quite limited. In addition to inter-disciplinary, multi-modality studies, bench-side work to better understand the process of cerebrotropism is needed to fuel more drug development and further improve outcomes.

Immune checkpoint inhibitors in challenging populations

Immune checkpoint inhibitors, including those targeting the programmed cell death 1/programmed cell death ligand 1 and cytotoxic T lymphocyte antigen 4 pathways, are revolutionizing cancer therapeutics. Both activity and toxicities largely stem from unleashing tumor- or host-specific cytotoxic T cells. Many patients seen in routine clinical practice have not qualified for or have been seriously underrepresented in immune checkpoint inhibitor clinical trials. Thus, a major gap in knowledge regarding the safety and efficacy of these agents persists in many populations, even after regulatory approval. To address this challenge, this review aggregates and synthesizes the available preclinical and clinical data surrounding immune checkpoint inhibitor therapy in challenging clinical populations to assist both academic and community oncologists in treatment decision making. Specifically, this review focuses on the safety and activity of immune checkpoint inhibitors in patients with autoimmune disorders, organ transplant patients, patients with chronic viral infections, patients with ongoing immunosuppressant use, patients with organ dysfunction, pregnant patients, patients with brain metastases, patients at extremes of age, and patients with an impaired functional status. Cancer 2017;123:1904-1911. © 2017 American Cancer Society.

History and current state of immunotherapy in glioma and brain metastasis

Malignant brain tumors such as glioblastoma (GBM) and brain metastasis have poor prognosis despite conventional therapies. Successful use of vaccines and checkpoint inhibitors in systemic malignancy has increased the hope that immune therapies could improve survival in patients with brain tumors. Manipulating the immune system to fight malignancy has a long history of both modest breakthroughs and pitfalls that should be considered when applying the current immunotherapy approaches to patients with brain tumors. Therapeutic vaccine trials for GBM date back to the mid 1900s and have taken many forms; from irradiated tumor lysate to cell transfer therapies and peptide vaccines. These therapies were generally well tolerated without significant autoimmune toxicity, however also did not demonstrate significant clinical benefit. In contrast, the newer checkpoint inhibitors have demonstrated durable benefit in some metastatic malignancies, accompanied by significant autoimmune toxicity. While this toxicity was not unexpected, it exceeded what was predicted from pre-clinical studies and in many ways was similar to the prior trials of immunostimulants. This review will discuss the history of these studies and demonstrate that the future use of immune therapy for brain tumors will likely need a personalized approach that balances autoimmune toxicity with the opportunity for significant survival benefit.

The Prognostic Value of BRAF, C-KIT, and NRAS Mutations in Melanoma Patients With Brain Metastases

PURPOSE

Brain metastases are a common problem in patients with melanoma, but little is known about the effect of gene mutations on survival in these patients.

METHODS AND MATERIALS

We created a retrospective multi-institutional database of 823 patients with melanoma and brain metastases diagnosed between 2006 and 2015. Clinical parameters, gene mutation status (BRAF, C-KIT, NRAS), and treatment were correlated with survival. Treatment patterns and outcomes were compared with a prior era (1985-2005).

RESULTS

BRAF status was known in 584 of 823 patients (71%). BRAF, NRAS, and C-KIT mutations were present in 51%, 22%, and 11% of tested patients, respectively. The median time from primary diagnosis to brain metastasis was 32 months, and overall median survival (MS) from the time of initial treatment of brain metastases was 10 months. MS for BRAF-positive and BRAF-negative patients was 13 months and 9 months, respectively (P=.02). There was no significant difference in MS in patients with or without NRAS or C-KIT mutations. The time from primary diagnosis to brain metastasis did not vary by mutation and was not associated with survival after the diagnosis of brain metastases. MS for the 1985 to 2005 and 2006 to 2015 cohorts was 6.7 months and 10.0 months, respectively (P<.01). Reflecting treatment-trend changes, use of whole-brain radiation therapy decreased from 48% to 26% during this period. Among BRAF-positive patients, 71% received targeted BRAF and/or MEK inhibitors and 57% received some combination of targeted therapy, chemotherapy, and/or immunotherapy.

CONCLUSIONS

For melanoma patients with brain metastases, BRAF-positive patients survive longer than BRAF-negative patients and overall survival has improved from 1985-2005 to 2006-2015.

Radiation and Immune Checkpoint Blockade: From Bench to Clinic

Immune escape of malignant cells is an important hallmark of cancer, necessary for tumor formation and progression. Accordingly, in recent years, therapies that enhance the immune system have had remarkable success in treating a myriad of malignancies. Particularly successful has been immune checkpoint blockade (ICB), which is a therapy that targets T-cell inhibitory receptors, or immune checkpoints. Despite these encouraging clinical results, most patients do not respond to such agents. Therefore, determining methods to better target and enhance the therapeutic efficacy of ICB is of paramount importance. One appealing approach is to use standard anticancer therapies, such as radiation, chemotherapy, and targeted biologics, to favorably modulate the immune system and enhance the anticancer immune response. For example, although radiation therapy has classically been thought of as a local therapy, there is significant potential for combining radiation therapy with ICB to both optimize local control and to treat metastatic disease. This concept is supported by numerous preclinical studies and clinical case reports and has since led to many early and ongoing clinical trials. However, it is still unclear how to optimally combine radiation and ICB to maximize the therapeutic effect. In this review, we highlight relevant preclinical and clinical studies in the field of radiation and ICB and discuss optimal strategies for combination therapies moving forward.

Toxicity of concurrent stereotactic radiotherapy and targeted therapy or immunotherapy: A systematic review

BACKGROUND AND PURPOSE

Both stereotactic radiotherapy (SRT) and immune- or targeted therapy play an increasingly important role in personalized treatment of metastatic disease. Concurrent application of both therapies is rapidly expanding in daily clinical practice. In this systematic review we summarize severe toxicity observed after concurrent treatment.

MATERIAL AND METHODS

PubMed and EMBASE databases were searched for English literature published up to April 2016 using keywords "radiosurgery", "local ablative therapy", "gamma knife" and "stereotactic", combined with "bevacizumab", "cetuximab", "crizotinib", "erlotinib", "gefitinib", "ipilimumab", "lapatinib", "sorafenib", "sunitinib", "trastuzumab", "vemurafenib", "PLX4032", "panitumumab", "nivolumab", "pembrolizumab", "alectinib", "ceritinib", "dabrafenib", "trametinib", "BRAF", "TKI", "MEK", "PD1", "EGFR", "CTLA-4" or "ALK". Studies performing SRT during or within 30days of targeted/immunotherapy, reporting severe (⩾Grade 3) toxicity were included.

RESULTS

Concurrent treatment is mostly well tolerated in cranial SRT, but high rates of severe toxicity were observed for the combination with BRAF-inhibitors. The relatively scarce literature on extra-cranial SRT shows a potential risk of increased toxicity when SRT is combined with EGFR-targeting tyrosine kinase inhibitors and bevacizumab, which was not observed for cranial SRT.

CONCLUSIONS

This review gives a best-possible overview of current knowledge and its limitations and underlines the need for a timely generation of stronger evidence in this rapidly expanding field.