Radiation and immunotherapy: a synergistic combination

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.

The Reciprocity between Radiotherapy and Cancer Immunotherapy

The clinical success of immune checkpoint inhibitors in treating metastatic and refractory cancers has generated significant interest in investigating their role in treating locally advanced diseases, thus requiring them to be combined with standard treatments in the hope of producing synergistic antitumor responses. Radiotherapy, in particular, has long been hypothesized to have actions complementary to those of immune checkpoint blockade, and a growing body of evidence indicates that cancer immunotherapy may also have radiosensitizing effects, which would provide unique benefit for locoregional treatments. Recent studies have demonstrated that when immune cells are activated by immunotherapeutics, they can reprogram the tumor microenvironment in ways that may potentially increase the radiosensitivity of the tumor. In this review, we highlight the evidence that supports reciprocal interactions between cancer immunotherapy and radiotherapy, where in addition to the traditional notion that radiation serves to enhance the activation of antitumor immunity, an alternative scenario also exists in which T-cell activation by cancer immunotherapy may sensitize tumors to radiation treatment through mechanisms that include normalization of the tumor vasculature and tissue hypoxia. We describe the empirical observations from preclinical models that support such effects and discuss their implications for future research and trial design.

Low-Dose Total Body Irradiation Can Enhance Systemic Immune Related Response Induced by Hypo-Fractionated Radiation

A systemic immune related response (SIME) of radiotherapy has been occasionally observed on metastatic tumors, but the clinical outcomes remain poor. Novel treatment approaches are therefore needed to improve SIME ratio. We used a combination of hypo-fractionated radiation therapy (H-RT) with low-dose total body irradiation (L-TBI) in a syngeneic mouse model of breast and colon carcinoma. The combination therapy of H-RT and L-TBI potentially enhanced SIME by infiltration of CD8⁺ T cell and altering the immunosuppressive microenvironment in non-irradiated subcutaneous tumor lesions. The frequency of IFN-γ, as a tumor-specific CD8⁺ T cells producing, significantly inhibited the secondary tumor growth of breast and colon. Our findings suggest that L-TBI could serve as a potential therapeutic agent for metastatic breast and colon cancer and, together with H-RT, their therapeutic potential is enhanced significantly.

Pharmacological reactivation of MYC-dependent apoptosis induces susceptibility to anti-PD-1 immunotherapy

Elevated MYC expression sensitizes tumor cells to apoptosis but the therapeutic potential of this mechanism remains unclear. We find, in a model of MYC-driven breast cancer, that pharmacological activation of AMPK strongly synergizes with BCL-2/BCL-X_L inhibitors to activate apoptosis. We demonstrate the translational potential of an AMPK and BCL-2/BCL-X_L co-targeting strategy in ex vivo and in vivo models of MYC-high breast cancer. Metformin combined with navitoclax or venetoclax efficiently inhibited tumor growth, conferred survival benefits and induced tumor infiltration by immune cells. However, withdrawal of the drugs allowed tumor re-growth with presentation of PD-1+/CD8+ T cell infiltrates, suggesting immune escape. A two-step treatment regimen, beginning with neoadjuvant metformin+venetoclax to induce apoptosis and followed by adjuvant metformin+venetoclax+anti-PD-1 treatment to overcome immune escape, led to durable antitumor responses even after drug withdrawal. We demonstrate that pharmacological reactivation of MYC-dependent apoptosis is a powerful antitumor strategy involving both tumor cell depletion and immunosurveillance.

Elevated MYC levels can sensitize tumor cells to apoptosis. In this study, the authors demonstrate that AMPK activation and BCL-2/BCL-X_L inhibition have a synergistic effect on apoptosis, and that together with anti PD-1 therapy they can suppress Myc-driven mammary tumor growth.

Recent Advances in Polymeric Nanomedicines for Cancer Immunotherapy

Immunotherapy has emerged as a promising approach to treat cancer, since it facilitates eradication of cancer by enhancing innate and/or adaptive immunity without using cytotoxic drugs. Of the immunotherapeutic approaches, significant clinical potentials are shown in cancer vaccination, immune checkpoint therapy, and adoptive cell transfer. Nevertheless, conventional immunotherapies often involve immune-related adverse effects, such as liver dysfunction, hypophysitis, type I diabetes, and neuropathy. In an attempt to address these issues, polymeric nanomedicines are extensively investigated in recent years. In this review, recent advances in polymeric nanomedicines for cancer immunotherapy are highlighted and thoroughly discussed in terms of 1) antigen presentation, 2) activation of antigen-presenting cells and T cells, and 3) promotion of effector cells. Also, the future perspectives to develop ideal nanomedicines for cancer immunotherapy are provided.

Novel stereotactic body radiation therapy (SBRT)-based partial tumor irradiation targeting hypoxic segment of bulky tumors (SBRT-PATHY): improvement of the radiotherapy outcome by exploiting the bystander and abscopal effects

Background

Despite the advances in oncology, patients with bulky tumors have worse prognosis and often receive only palliative treatments. Bulky disease represents an important challenging obstacle for all currently available radical treatment options including conventional radiotherapy. The purpose of this study was to assess a retrospective outcome on the use of a newly developed unconventional stereotactic body radiation therapy (SBRT) for PArtial Tumor irradiation of unresectable bulky tumors targeting exclusively their HYpoxic segment (SBRT-PATHY) that exploits the non-targeted effects of radiotherapy: bystander effects (local) and the abscopal effects (distant).

Materials and methods

Twenty-three patients with bulky tumors received partial bulky irradiation in order to induce the local non-targeted effect of radiation (bystander effect). The hypoxic tumor segment, called the bystander tumor volume (BTV), was defined using PET and contrast-enhanced CT, as a hypovascularized-hypometabolic junctional zone between the central necrotic and peripheral hypervascularized-hypermetabolic tumor segment. Based on tumor site and volume, the BTV was irradiated with 1–3 fractions of 10–12 Gy prescribed to 70% isodose-line. The pathologic lymph nodes and metastases were not irradiated in order to assess the distant non-targeted effects of radiation (abscopal effect). No patient received any systemic therapy.

Results

At the time of analysis, with median follow-up of 9.4 months (range: 4–20), 87% of patients remained progression-free. The bystander and abscopal response rates were 96 and 52%, respectively. Median shrinkage of partially irradiated bulky tumor expressing intensity of the bystander effect was 70% (range 30–100%), whereas for the non-irradiated metastases (intensity of the abscopal effect), it was 50% (range 30–100%). No patient experienced acute or late toxicity of any grade.

Conclusions

SBRT-PATHY showed very inspiring results on exploitation of the radiation-hypoxia-induced non-targeted effects that need to be confirmed through our ongoing prospective trial.

Present study has been retrospectively registered by the local ethic committee under study number A 26/18.

Immunotherapy for High Grade Gliomas: A Clinical Update and Practical Considerations for Neurosurgeons

The current standard of care for patients with high grade gliomas includes surgical resection, chemotherapy, and radiation; but even still the majority of patients experience disease progression and succumb to their illness within a few years of diagnosis. Immunotherapy, which stimulates an anti-tumor immune response, has been revolutionary in the treatment of some hematological and solid malignancies, generating substantial excitement for its potential for patients with glioblastoma. The most commonly used immunotherapies include dendritic cell and peptide vaccines, checkpoint inhibitors, and adoptive T cell therapy. However, to date, the preclinical success of these approaches against high-grade glioma models has not been replicated in human clinical trials. Moreover, the complex response to these biologically active treatments can complicate management decisions, and the neurosurgical oncology community needs to be actively involved in and up to date on the use of these agents in high grade glioma patients. In this review, we discuss the challenges immunotherapy faces for high grade gliomas, the completed and ongoing clinical trials for the major immunotherapies, and the nuances in management for patients being actively treated with one of these agents.

Durvalumab for stage III non-small-cell lung cancer patients: clinical evidence and real-world experience

Stage III non-small cell lung cancer (NSCLC) has a dismal prognosis, with only 15-20% of patients alive at 5 years after concomitant chemo-radiotherapy, which represents the standard treatment. Targeting immune-checkpoint inhibitors represents a standard option for advanced NSCLC. Improvements in understanding of the immune profile of NSCLC has led to the development of immunotherapeutic strategies, including inhibitory molecules responsible for abrogating an anticancer immune response such as programmed cell-death 1 and programmed cell-death ligand 1. A recently published phase III trial (PACIFIC) showed for the first time an improved overall survival in stage III NSCLC patients with consolidative durvalumab. The aim of this review is to summarize and discuss the clinical evidence for the use of durvalumab in stage III NSCLC, with a brief overview on future perspectives in this setting.

Local biomaterials-assisted cancer immunotherapy to trigger systemic antitumor responses

Cancer immunotherapy by educating or stimulating patients’ own immune systems to attack cancer cells has demonstrated promising therapeutic responses in the clinic.

Rationale for combination of radiation therapy and immune checkpoint blockers to improve cancer treatment

Radiation therapy for cancer is considered to be immunosuppressive. However, the cellular response after radiation therapy may stimulate or suppress an immune response. The effect may vary with the tumor type and occasionally tumor regressions have been observed outside the irradiated volume, both in animal studies and in the clinic. A renewed interest in the role of immunity for the observed effect of radiation came with the current recognized role of immune checkpoint blockers (ICBs) for control of selected cancer types. We therefore here review preclinical studies and clinical reports on the interaction of ICBs and radiation as a basis for further clinical trials. Some tumor types where the combination of these modalities seems especially promising are also proposed.

Association of markers of systemic and local inflammation with prognosis of patients with rectal cancer who received neoadjuvant radiotherapy

PURPOSE

The inflammatory status of patients with cancer appears to affect cancer progression and patient prognosis. We examined the characteristics of cancer-associated systemic and local inflammation and its impact on the overall survival (OS) of patients with locally advanced rectal cancer (LARC) who received neoadjuvant radiotherapy (nRT).

PATIENTS AND METHODS

Seventy-six consecutive LARC patients who received nRT from February 2012 to September 2015 were retrospectively analyzed. The peripheral neutrophil-to-lymphocyte ratio (NLR) was determined at diagnosis, and the CD8+ T-cell count was determined from surgical specimens. Factors associated with OS were identified by univariate and multivariate Cox regression.

RESULTS

The median follow-up time was 23.0 months (range: 2-59), and the overall 5-year OS rate was 68.6% (95% CI =46.06-91.14). Patients with a high NLR (≥2.0) and a low CD8+ T-cell count (<9%) had a significantly worse 5-year OS than those with a low NLR and a high CD8+ T-cell count (P=0.005). NLR was also associated with lymphovascular invasion (P=0.014) and T stage (P=0.047), and the CD8+ T-cell count was associated with mucinous adenocarcinoma (P=0.005) and T stage (P=0.049). An NLR <2.0 was associated with pathological complete regression after nRT (P=0.039). Multivariate Cox regression indicated that NLR (P=0.025), CD8+ T-cell count (P=0.018), age (P=0.020), lymphovascular invasion (P=0.038), and T stage (P=0.011) were independently associated with OS.

CONCLUSION

A high NLR and a low CD8+ T-cell count were significantly associated with poor survival in our population of patients with LARC. Measurement of markers of systemic and local inflammation might help to predict the prognosis of patients with LARC after nRT.

Radiation, Immune Checkpoint Blockade and the Abscopal Effect: A Critical Review on Timing, Dose and Fractionation

The combination of radiation and immunotherapy is currently an exciting avenue of pre-clinical and clinical investigation. The synergy between these two treatment modalities has the potential to expand the role of radiation from a purely local therapy, to a role in advanced and metastatic disease. Tumor regression outside of the irradiated field, known as the abscopal effect, is a recognized phenomenon mediated by lymphocytes and enhanced by checkpoint blockade. In this review, we summarize the known mechanistic data behind the immunostimulatory effects of radiation and how this is enhanced by immunotherapy. We also provide pre-clinical data supporting specific radiation timing and optimal dose/fractionation for induction of a robust anti-tumor immune response with or without checkpoint blockade. Importantly, these data are placed in a larger context of understanding T-cell exhaustion and the impact of immunotherapy on this phenotype. We also include relevant pre-clinical studies done in non-tumor systems. We discuss the published clinical trials and briefly summarize salient case reports evaluating the abscopal effect. Much of the data discussed here remains at the preliminary stage, and a number of interesting avenues of research remain under investigation.

Tumor microenvironment classification based on T-cell infiltration and PD-L1 in patients with mismatch repair-proficient and -deficient colorectal cancer

The classification of tumor microenvironments according to the presence or absence of tumor infiltrating lymphocytes (TILs) and programmed death ligand-1 (PD-L1) expression has been used to predict the efficacy of immune checkpoint inhibitor antibodies in several cancer types, not including colorectal cancer (CRC). The current study investigated the TIL/PD-L1 status of patients with CRC, particularly patients who presented as mismatch repair-proficient (pMMR) and mismatch repair-deficient (dMMR). A total of 243 patients with CRC were enrolled and defined as pMMR (121 patients) or dMMR (122 patients). Using Pearson's χ² test and multivariable multinomial logistic regression analysis, the associations between MMR status, TIL presence and PD-L1 expression were investigated, in addition to the association between TIL/PD-L1 status and clinicopathological features. The results demonstrated that the dMMR group more frequently exhibited TIL⁺ (85/122 vs. 61/121) and PD-L1⁺ (49/122 vs. 32/121) phenotypes compared with the pMMR group. PD-L1⁺ expression was identified in 42.4% of TIL⁺ cases in the dMMR group, while only 18.0% of TIL⁺ cases were PD-L1⁺ in the pMMR group. High programmed death-1 expression and dMMR status were revealed as two independent risk factors for TIL⁺ PD-L1⁺ status. In conclusion, compared with the pMMR group, the dMMR group was more likely to present with a TIL⁺ PD-L1⁺ status, which suggests that a TIL⁺ PD-L1⁺ tumor microenvironment may partly contribute to the improved response of dMMR patients to anti-PD-1/L1 therapy.

Correlation between tumor microenvironment-associated factors and the efficacy and prognosis of neoadjuvant therapy for rectal cancer

The tumor microenvironment contributes to the survival and development of tumor cells and is therefore a key target for cancer therapy. The tumor microenvironment has unique physical and chemical properties and is associated with inflammation and immunity. To examine the correlation between tumor microenvironment-associated factors and the efficacy and prognosis of neoadjuvant therapy for rectal cancer, and to compare the differences between two treatments [neoadjuvant chemotherapy (NAC) vs. neoadjuvant chemoradiotherapy (NACR)], an immunohistochemical method was used to measure the expression levels of CD4⁺ tumor-infiltrating lymphocytes (TILs), cluster of differentiation (CD)8⁺TILs, forkhead box P3 (FOXP3)⁺TILs, cytotoxic T lymphocyte-associated antigen-4⁺TILs and programmed death ligand-1 (PD-L1)⁺TILs in 109 patients with rectal cancer, pre- and post-neoadjuvant therapy. The significance of these protein expression patterns was also analyzed using tissue microarrays, and the prognostic significance of these findings evaluated. The results indicated that high levels of CD4⁺TILs, CD8⁺TILs and PD-L1⁺TILs may be associated with favorable responses to neoadjuvant therapy, whereas high levels of FOXP3⁺TILs were associated with poor therapeutic responses. Expression levels of CD8⁺TILs and FOXP3⁺TILs following neoadjuvant therapy were independent prognostic factors and affected the total survival of patients subjected to neoadjuvant therapy for the treatment of rectal cancer. Moreover, the effects of NAC and NACR on the tumor microenvironment may be different.

Adjuvant Radiation Therapy After Radical Nephrectomy in Patients with Localized Renal Cell Carcinoma: A Systematic Review and Meta-analysis

CONTEXT

Adjuvant radiation therapy has been recommended for patients at higher risk of relapse from renal cell carcinoma (RCC) to improve disease-free survival (DFS) and overall survival (OS) after radical nephrectomy.

OBJECTIVE

To quantify the benefit of adjuvant radiation therapy.

EVIDENCE ACQUISITION

A systematic review of electronic databases identified publications exploring the association between adjuvant radiation therapy and locoregional recurrence (LRR), DFS, and OS among patients after radical nephrectomy for early-stage RCC. Hazard ratios for DFS were weighted and pooled using the generic inverse variance and random effects model. Odds ratios for LRR, DFS, and OS at 5yr were weighted and pooled in a meta-analysis using Mantel-Haenszel random-effects modeling.

EVIDENCE SYNTHESIS

Twelve studies comprising 1624 patients were included in the analysis. Ten studies were retrospective and two were randomized controlled trials. Adjuvant radiation therapy was delivered to 37% of patients. The median follow-up was 49mo. Adjuvant radiation therapy was not associated with better DFS or OS at 5yr, but was associated with less LRR.

CONCLUSIONS

With the caveat that confounding by indication may result from pooling data from predominantly nonrandomized studies, adjuvant radiation after radical nephrectomy was not associated with improved DFS or OS but was associated with less LRR.

PATIENT SUMMARY

Radiation therapy after resection of renal cell carcinoma with a high risk of relapse may reduce the risk of local recurrence but not the risk of disease recurrence or death after 5yr.

Metabolic reprogramming by Dichloroacetic acid potentiates photodynamic therapy of human breast adenocarcinoma MCF-7 cells

Aberrant glycolytic metabolism is one of the hallmarks of carcinogenesis and therefore reversal of metabolic transformation is a promising drug target in cancer treatment strategies. Dichloroacetic acid (DCA) is known to target the glycolytic pathway in cancer cells and facilitates reversal of metabolic transformation from aerobic cytosolic accumulation of pyruvic acid, "the Warburg effect", to mitochondrial oxidative phosphorylation. Recently, combination therapy particularly involving photodynamic therapy (PDT) has received considerable attention in oncology. We hypothesized that if DCA and PDT are combined, they might potentiate mitochondrial dysfunction and induce apoptosis by a reactive oxygen species (ROS) dependent pathway. We used MCF-7 cells as our in vitro model and 5-aminolevulinic acid (5-ALA) dependent PDT therapy to test our hypothesis. We found that combinatorial treatment of MCF-7 cells with PDT and DCA not only increased cell growth inhibition, but also affected mitochondrial membrane integrity perhaps via production of ROS, and enhanced apoptosis. Further, our results on ATP release during the combined treatment demonstrate that immunogenic cell death (ICD) is likely to be a potential mechanism by which PDT and DCA induce cancer cell death. Taken together, our study suggests a novel way of sensitizing MCF-7 cells for accelerated induction of apoptosis and ICD in these cells. The findings included in this study might have direct relevance in breast cancer treatment strategies.

Gliomatosis cerebri: a consensus summary report from the Second International Gliomatosis cerebri Group Meeting, June 22-23, 2017, Bethesda, USA

Gliomatosis cerebri (GC) is an aggressive glioma characterized by an invasive growth pattern and a dismal prognosis. The low incidence and non-specific symptoms at presentation pose unique challenges for early diagnosis and disease-specific research. There is no standard of care for the treatment of patients with a GC phenotype. Understanding the biology of this entity is a critical step in determining effective treatments. Toward this end, the Second International GC Group convened at National Institutes of Health, Bethesda on June 22nd-23rd 2017. This paper summarizes the main conclusions and recommendations for research priorities to fight this fatal condition.

Phase II study of neoadjuvant checkpoint blockade in patients with surgically resectable undifferentiated pleomorphic sarcoma and dedifferentiated liposarcoma

BACKGROUND

Soft tissue sarcomas are a heterogeneous and rare group of solid tumors of mesenchymal origin that can arise anywhere in the body. Although surgical resection is the mainstay of treatment for patients with localized disease, disease recurrence is common and 5-year overall survival is poor (~ 65%). Both radiation therapy and conventional chemotherapy are used to reduce local and distant recurrence. However, the utility of radiation therapy is often limited by disease location (in the case of retroperitoneal sarcomas, for instance) while systemic therapy with conventional lines of chemotherapy offer limited efficacy and are often poorly tolerated and associated with significant toxicity. Within the past decade, major advances have been made in the treatment of other malignancies including melanoma, renal cell carcinoma, and non-small cell lung carcinoma with the advent of immune-checkpoint inhibitors such as ipilimumab (anti-CTLA4), pembrolizumab (anti-PD1), and nivolumab (anti-PD1). The recently published SARC028 (NCT02301039), an open label, phase II, multicenter trial of pembrolizumab in patients with advanced bone and soft tissue sarcomas reported promising activity in select histologic subtypes of advanced STS, including undifferentiated pleomorphic sarcoma and dedifferentiated liposarcoma.

METHODS

There is a clear need for novel and effective adjuncts in the treatment of STS. We hypothesize that immune checkpoint blockade will be effective in patients with surgically resectable primary or locally recurrent dedifferentiated liposarcoma and undifferentiated pleomorphic sarcoma when administered in the neoadjuvant setting. The primary aim of this phase II, single-center, open label, randomized non-comparative trial is to determine the pathologic response to neoadjuvant nivolumab monotherapy and combination nivolumab/ipilimumab in patients with resectable dedifferentiated liposarcoma of the retroperitoneum or undifferentiated pleomorphic sarcoma of the trunk or extremity treated with concurrent standard of care neoadjuvant radiation therapy.

DISCUSSION

This study will help define the role of single agent anti-PD1 and combination anti-CTLA4 and anti-PD1 therapy in patients with surgically resectable dedifferentiated liposarcoma and undifferentiated pleomorphic sarcoma.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03307616 , registered October 12, 2017.

High linear energy transfer carbon-ion irradiation increases the release of the immune mediator high mobility group box 1 from human cancer cells

Anti-tumor immunity modulates the local effects of radiation therapy. High mobility group box 1 (HMGB1) plays a pivotal role in activating antigen-specific T-cell responses. Here, we examined the relationship between linear energy transfer (LET) and HMGB1 release. We assessed the proportions of KYSE-70, HeLa and SiHa cells surviving after carbon-ion (C-ion) beam irradiation with different LET values, using a clonogenic assay. The D10, the dose at which 10% of cells survived, was calculated using a linear-quadratic model. HMGB1 levels in the culture supernatants of C-ion beam-irradiated tumor cells were assessed by enzyme-linked immunosorbent assay. The D10 doses for 13 keV/μm of C-ion irradiation in KYSE-70, HeLa and SiHa cells were 2.8, 3.9 and 4.1 Gy, respectively, whereas those for 70 keV/μm C-ion irradiation were 1.4, 1.9 and 2.3 Gy, respectively. We found that 70 keV/μm of C-ion irradiation significantly increased HMGB1 levels in the culture supernatants of all cell lines 72 h after irradiation compared with non-irradiated controls. Furthermore, 70 keV/μm of C-ion irradiation significantly increased HMGB1 levels in the culture supernatants of all cell lines 72 h after irradiation compared with 13 keV/μm. The results suggest that HMGB1 release from several cancer cell lines increases with increased LET.

Inhibiting the CD8+ T cell infiltration in the tumor microenvironment after radiotherapy is an important mechanism of radioresistance

Endogenous immune response participates in tumor control, and radiotherapy has immune modulatory capacity, but the role of immune modulation in the tumor microenvironment invoked by radiotherapy in radiosensitivity is poorly defined. In the present study, a radio-resistant melanoma cell line was obtained after repeated irradiation to the parental tumor in C57BL/6 mice. Radiotherapy resulted in aggregation of CD8⁺ and CD3⁺ T cells, and decrease of myeloid-derived suppressor cells and dendritic cells in the parental tumor, but not in the resistant tumors. CD4⁺ T cells and B cells did not change significantly. The CD8⁺ T cell infiltration after radiotherapy is important for tumor response, because in the nude mice and CD8⁺ T cell-depleted C57BL/6 mice, the parental and resistant tumor has similar radiosensitivity. Patients with good radiation response had more CD8⁺ T cells aggregation after radiotherapy. Radiotherapy resulted in robust transcription of T cell chemoattractant in the parental cells, and the expression of CCL5 was much higher. These results reveal a novel mechanism of radioresistance, tumor cells inhibit the infiltration of CD8⁺ T cell after radiotherapy and become radioresistant. Increasing CD8⁺ T cell infiltration after RT may be an effective way to improve tumor radiosensitivity.

Checkpoint blockade-based immunotherapy in the context of tumor microenvironment: Opportunities and challenges

A dynamic and mutualistic interaction between tumor cells and tumor microenvironment (TME) promotes the progression and metastasis of solid tumors. Cancer immunotherapy is becoming a major treatment paradigm for a variety of cancers. Although immunotherapy, especially the use of immune checkpoint inhibitors, has achieved clinical success, only a minority of patients exhibits durable responses. Clinical studies directed at identifying appropriate biomarkers and immune profiles that can be used to predict immunotherapy responses are presently being conducted. Combining treatment strategies tailored to cancer-immune interactions are designed to increase the rate of durable clinical response in patients. It is essential to establish a reasonable tumor classification strategy according to TME to improve cancer immunotherapy. In the current review, a modified classification of TME is proposed, and optimization of TME classification is needed through detailed and integrated molecular characterization of large patient cohorts in the future.

Harnessing and Optimizing the Interplay between Immunotherapy and Radiotherapy to Improve Survival Outcomes

In the past, radiotherapy was primarily used to control local disease, but recent technological advances in accurate, high-dose ionizing radiation (IR) delivery have not only increased local tumor control but in some cases reduced metastatic burden. These "off target" therapeutic effects of IR at nonirradiated tumor sites, also known as abscopal effects, are thought to be mediated by tumor antigen-primed T cells that travel to metastatic sites and promote tumor regression. Similarly, early indications reveal that IR in combination with immune checkpoint inhibitors, such as ipilimumab (anti-CTLA-4) and nivolumab (anti-PD-1), can provide superior therapeutic responses. These observations suggest that local radiotherapy results in altered gene expression, exposure of new antigens, or cell death that can interact with immunotherapy. As such, radiotherapy enhancement of immune responses offers a promising synergy with the potential for substantial clinical benefit. This review focuses on the biology that underlies the mechanisms for the interaction between radiation-induced tumor cell death and enhanced immunologic response. Mol Cancer Res; 16(8); 1209-14. ©2018 AACR.

Reirradiation for locoregionally recurrent non-small cell lung cancer

Locoregional failure in non-small cell lung cancer (NSCLC) remains high, and the management for recurrent disease in the setting of prior radiotherapy is difficult. Retreatment options such as surgery or systemic therapy are typically limited or frequently result in suboptimal outcomes. Reirradiation (reRT) of thoracic malignancies may be an optimal strategy for providing definitive local control and offering a new chance of cure. Yet, retreatment with radiation therapy can be challenging for fear of excessive toxicities and the inability to safely deliver definitive (≥60 Gy) doses of reRT. However, with recent improvements in radiation delivery techniques and image-guidance, dose-escalation with reRT is possible and outcomes are encouraging. Here, we present a review of various radiation techniques, clinical outcomes and associated toxicities in patients with locoregionally recurrent NSCLC treated primarily with reRT.

Present and future of cancer immunotherapy: A tumor microenvironmental perspective

Modulation of the tumor microenvironment is becoming an increasingly popular research topic in the field of immunotherapy, and studies regarding immune checkpoint blockades and cancer immunotherapy have pushed cancer immunotherapy to a climax. Simultaneously, the manipulation of the immune regulatory pathway can create an effective immunotherapy strategy; however, the tumor microenvironment serves an important role in suppressing the antitumor immunity by its significant heterogeneity. A number of patients with cancer do not have a good response to monotherapy approaches; therefore, combination strategies are required to achieve optimal therapeutic benefits. Targeting the tumor microenvironment may provide a novel strategy for immunotherapy, break down the resistance of conventional cancer therapy and produce the foundation for personalized precision medicine. The present review summarized the research regarding cancer immunotherapy from the perspective of how the tumor microenvironment affects the immune response, with the aim of proposing a novel strategy for cancer immunotherapy and combination therapy.

Characterizing parathyroid carcinomas and atypical neoplasms based on the expression of programmed death-ligand 1 expression and the presence of tumor-infiltrating lymphocytes and macrophages

BACKGROUND

Four distinct tumor microenvironments have been proposed based on the expression of programmed death-ligand 1 and the presence of tumor-infiltrating lymphocytes: immunotype I (adaptive resistance, tumor-infiltrating lymphocytes+ and programmed death-ligand 1+); immunotype II (immunologic ignorance, tumor-infiltrating lymphocytes- and programmed death-ligand 1-); immunotype III (intrinsic induction; tumor-infiltrating lymphocytes- and programmed death-ligand 1+); and immunotype IV (tolerance, tumor-infiltrating lymphocytes+ and programmed death-ligand 1-). These subtypes may predict tumor response to immunotherapy. We hypothesized that parathyroid neoplasms may have tumor immunogenic expression that can later be used to guide treatment.

METHODS

We assessed retrospectively the immunohistochemical expression of programmed death-ligand 1 and the presence of tumor-infiltrating lymphocytes (CD3+ and CD8+) and macrophages (CD68+) in parathyroid carcinomas and in atypical parathyroid neoplasms treated at the M. D. Anderson Cancer Center from 1996 to 2016. Using intratumoral digital image analysis, the programmed death-ligand 1 H score was calculated with a standardized formula for predominant staining. The tumor-infiltrating lymphocytes per square millimeter of intratumoral areas were quantified.

RESULTS

Within 30 specimens (17 parathyroid carcinomas and 13 atypical parathyroid neoplasms), there was no difference in the median programmed death-ligand 1 H score between the two groups (P = .57). Four parathyroid carcinoma cases had programmed death-ligand 1 H scores ≥1 associated with CD3+ and CD8+ tumor cell density; 2 of them had distant metastases. Parathyroid carcinomas had a lesser median CD3+ density (P = .04) and a lesser median CD8+ density (P =.07) than did atypical parathyroid neoplasms. Median CD68+ density did not differ between groups (P = .22).

CONCLUSION

Parathyroid carcinomas tended to have immune-ignorant and immune-tolerant microenvironments within the neoplasm (immunotypes II and IV). Of the parathyroid carcinoma microenvironments, 17 had patterns of programmed death-ligand 1 and tumor-infiltrating lymphocytes expression (immunotype I), suggesting possible benefit from immunotherapy. In addition, both parathyroid carcinomas and parathyroid neoplasms expressed CD68+. Further exploration of these potential biomarkers as a target in cancer therapies is needed.

Feasibility of split-course stereotactic ablative radiotherapy for oligometastases

Background

There is growing interest in the use of stereotactic ablative radiotherapy (SABR) for oligometastases. However, extreme caution should be exercised in treating tumors closely located to organs at risk (OARs) with SABR. To reduce complications, we have applied split-course SABR to oligometastases closely located to OARs or to those being retreated with radiotherapy.

Methods

We retrospectively reviewed the records of patients with oligometastases who were treated with planned split-course SABR between January 2012 and December 2016.

Results

A total of 23 patients with 29 oligometastatic lesions were enrolled. The primary diagnoses were bone and soft tissue cancers in 13 lesions, liver cancers in 12 lesions, and colorectal cancers in four lesions. The median tumor volume was 78 cm3 (range, 4-1781 cm3). The lesions were treated with 1-3 fractions in the first stage of SABR (first SABR), and one or two fractions in the second stage of SABR (second SABR). The time interval between the two stages was about 4 weeks. A partial response was noted in 16 lesions (55%) after the first SABR, and practical reductions in the doses to OARs were observed in the second SABR compared with the first SABR. The 1-, 2- and 3-year local control rates were 92%, 65% and 43%, respectively. No Grade 4 or 5 toxicities were observed during or after treatment.

Conclusion

Split-course SABR appeared to be feasible for the treatment of oligometastases closely located to OARs.

Immunomodulation by ionizing radiation-impact for design of radio-immunotherapies and for treatment of inflammatory diseases

Ionizing radiation is often regarded as an element of danger. But, danger responses on the cellular and molecular level are often beneficial with regard to the induction of anti-tumor immunity and for amelioration of inflammation. We outline how in dependence of radiation dose and fraction, radiation itself-and especially in combination with immune modulators-impacts on the innate and adaptive immune system. Focus is set on radiation-induced changes of the tumor cell phenotype and the cellular microenvironment including immunogenic cancer cell death. Mechanisms how anti-tumor immune responses are triggered by radiotherapy in combination with hyperthermia, inhibition of apoptosis, the adjuvant AnnexinA5, or vaccination with high hydrostatic pressure-killed autologous tumor cells are discussed. Building on this, feasible multimodal radio-immunotherapy concepts are reviewed including overcoming immune suppression by immune checkpoint inhibitors and by targeting TGF-β. Since radiation-induced tissue damage, inflammation, and anti-tumor immune responses are interconnected, the impact of lower doses of radiation on amelioration of inflammation is outlined. Closely meshed immune monitoring concepts based on the liquid biopsy blood are suggested for prognosis and prediction of cancer and non-cancer inflammatory diseases. Finally, challenges and visions for the design of cancer radio-immunotherapies and for treatment of benign inflammatory diseases are given.

Mathematical modelling of the synergistic combination of radiotherapy and indoleamine-2,3-dioxygenase (IDO) inhibitory immunotherapy against glioblastoma

Objective:

Recent research has shown that combining radiotherapy and immunotherapy can counteract the ability of cancer to evade and suppress the native immune system. To optimise the synergy of the combined therapies, factors such as radiation dose and fractionation must be considered, alongside numerous parameters resulting from the complexity of cancer–immune system interactions. It is instructive to use mathematical models to tackle this problem.

Methods:

In this work, we adapted a model primarily to describe the synergistic effect between single-fraction radiotherapy and immunotherapy (1-methyl tryptophan) observed in previous experiments with glioblastoma-carrying rats. We also showed how the model can be used to generate hypotheses on the outcome of other treatment fractionation schemes.

Results:

The model successfully reproduced the results of the experiments. Moreover, it provided support for the hypothesis that, for a given biologically effective dose, the efficacy of the combination therapy and the synergy between the two therapies are favoured by the administration of radiotherapy in a hypofractionated regime. Furthermore, for a double-fraction irradiation regimen, the synergy is favoured by a short time interval between the treatment fractions.

Conclusion:

It was concluded that the model could be fitted to reproduce the experimental data well within its uncertainties. It was also demonstrated that the fitted model can be used to form hypotheses to be validated by further pre-clinical experiments.

Advances in knowledge:

The results of this work support the hypothesis that the synergetic action of combined radiotherapy and immunotherapy is favoured by using a hypofractionated radiation treatment regimen, given over a short time interval.

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.

Using immunotherapy to boost the abscopal effect

More than 60 years ago, the effect whereby radiotherapy at one site may lead to regression of metastatic cancer at distant sites that are not irradiated was described and called the abscopal effect (from 'ab scopus', that is, away from the target). The abscopal effect has been connected to mechanisms involving the immune system. However, the effect is rare because at the time of treatment, established immune-tolerance mechanisms may hamper the development of sufficiently robust abscopal responses. Today, the growing consensus is that combining radiotherapy with immunotherapy provides an opportunity to boost abscopal response rates, extending the use of radiotherapy to treatment of both local and metastatic disease. In this Opinion article, we review evidence for this growing consensus and highlight emerging limitations to boosting the abscopal effect using immunotherapy. This is followed by a perspective on current and potential cross-disciplinary approaches, including the use of smart materials to address these limitations.

Immunotherapy in the Asiatic population: any differences from Caucasian population?

As "Immunotherapy age" is coming, immune checkpoint inhibitors (CPI) therapies have shown favorable clinical benefits and low toxicity profiles in patients with advanced non-small cell lung cancer (NSCLC). While it is a pity that there is a little clear clinical trials evidence about immunotherapy among Asian population. Moreover, since there is an ethnic difference for targeted therapy, what about immunotherapy? Which factors may associate with ethnic differences from Caucasian population to Asiatic population? In this review, we supposed that the characteristics of the much higher proportion of EGFR mutation, hepatitis B virus infection and unexpected immune-related toxicity among Asian patients should be considered.

Tryptophan Metabolism Contributes to Radiation-Induced Immune Checkpoint Reactivation in Glioblastoma

Purpose: Immune checkpoint inhibitors designed to revert tumor-induced immunosuppression have emerged as potent anticancer therapies. Tryptophan metabolism represents an immune checkpoint, and targeting this pathway's rate-limiting enzyme IDO1 is actively being investigated clinically. Here, we studied the intermediary metabolism of tryptophan metabolism in glioblastoma and evaluated the activity of the IDO1 inhibitor GDC-0919, both alone and in combination with radiation (RT).Experimental Design: LC/GC-MS and expression profiling was performed for metabolomic and genomic analyses of patient-derived glioma. Immunocompetent mice were injected orthotopically with genetically engineered murine glioma cells and treated with GDC-0919 alone or combined with RT. Flow cytometry was performed on isolated tumors to determine immune consequences of individual treatments.Results: Integrated cross-platform analyses coupling global metabolomic and gene expression profiling identified aberrant tryptophan metabolism as a metabolic node specific to the mesenchymal and classical subtypes of glioblastoma. GDC-0919 demonstrated potent inhibition of this node and effectively crossed the blood-brain barrier. Although GDC-0919 as a single agent did not demonstrate antitumor activity, it had a strong potential for enhancing RT response in glioblastoma, which was further augmented with a hypofractionated regimen. RT response in glioblastoma involves immune stimulation, reflected by increases in activated and cytotoxic T cells, which was balanced by immune checkpoint reactivation, reflected by an increase in IDO1 expression and regulatory T cells (Treg). GDC-0919 mitigated RT-induced Tregs and enhanced T-cell activation.Conclusions: Tryptophan metabolism represents a metabolic node in glioblastoma, and combining RT with IDO1 inhibition enhances therapeutic response by mitigating RT-induced immunosuppression. Clin Cancer Res; 24(15); 3632-43. ©2018 AACR.

Radiation improves antitumor effect of immune checkpoint inhibitor in murine hepatocellular carcinoma model

Background & aims

Although immunotherapy has emerged as an attractive therapy for refractory cancers, its limited efficacy in hepatocellular carcinoma (HCC) suggests the need for a combination strategy that can either enhance or complement therapeutic effect. We investigated whether combination of immune checkpoint blockade (ICB) and radiation could enhance antitumor effect in a murine HCC model.

Methods

Using murine HCC, HCa-1, the effect of radiation on programmed death-ligand1 (PD-L1) expression was determined by real-time PCR, flow cytometry, and western blotting. Signaling pathways involved in altered PD-L1 expression were examined. Tumor growth and survival rate were evaluated for a combination of anti-PD-L1 and radiation. Immunological parameters in the tumor were assessed using flow cytometry and histological study.

Results

Radiation upregulated PD-L1 expression in tumor cells through IFN-γ/STAT3 signaling, which could facilitate therapeutic action of anti-PD-L1. Combination of anti-PD-L1 and radiation significantly suppressed tumor growth compared to treatment with anti-PD-L1 alone or radiation alone group (P<0.01). Survival was significantly improved in the combination group compared to anti-PD-L1 alone or radiation alone group (7-week survival rate; 90% vs. 0% or 30%, respectively, P<0.001). The underlying mechanism involved increasing apoptosis, decreasing tumor cell proliferation, as well as restoration of CD8⁺ T cell functions.

Conclusions

The combination of anti-PD-L1 and radiation significantly improved the antitumor effect shown in tumor growth delay as well as in survival, supporting a novel combination strategy of immunoradiotherapy in HCC.

TIME (Tumor Immunity in the MicroEnvironment) classification based on tumor CD274 (PD-L1) expression status and tumor-infiltrating lymphocytes in colorectal carcinomas

Inhibitors targeting the PDCD1 (programmed cell death 1, PD-1) immune checkpoint pathway have revolutionized cancer treatment strategies. The TIME (Tumor Immunity in the MicroEnvironment) classification based on tumor CD274 (PDCD1 ligand 1, PD-L1) expression and tumor-infiltrating lymphocytes (TIL) has been proposed to predict response to immunotherapy. It remains to be determined clinical, pathological, and molecular features of TIME subtypes of colorectal cancer. Using 812 colon and rectal carcinoma cases from the Nurses' Health Study and Health Professionals Follow-up Study, we examined the association of tumor characteristics and survival outcomes with four TIME subtypes (TIME 1, CD274^low/TIL^absent; TIME 2, CD274^high/TIL^present; TIME 3, CD274^low/TIL^present; and TIME 4, CD274^high/TIL^absent). In survival analyses, Cox proportional hazards models were adjusted for potential confounders, including microsatellite instability (MSI) status, CpG island methylator phenotype (CIMP) status, LINE-1 methylation level, and KRAS, BRAF, and PIK3CA mutation status. TIME subtypes 1, 2, 3 and 4 had 218 (27%), 117 (14%), 103 (13%), and 374 (46%) colorectal cancer cases, respectively. Compared with TIL-absent subtypes (TIME 1 and 4), TIL-present subtypes (TIME 2 and 3) were associated with high-level MSI, high-degree CIMP, BRAF mutation, and higher amounts of neoantigens (p < 0.001). TIME subtypes were not significantly associated with colorectal cancer-specific or overall survival. In conclusion, TIL-present TIME subtypes of colorectal cancer are associated with high levels of MSI and neoantigen load, supporting better responsiveness to cancer immunotherapy. Further studies examining tumor molecular alterations and additional factors in the tumor microenvironment may inform development of immunoprevention and immunotherapy strategies.

Nanoparticles for dendritic cell-based immunotherapy

Crosstalk among immune cells has attracted considerable attention with the advent of immunotherapy as a novel therapeutic approach for challenging diseases, especially cancer, which is the leading cause of mortality worldwide. Dendritic cells-the key antigen-presenting cells-play a pivotal role in immunological response by presenting exogenous epitopes to T cells, which induces the self-defense mechanisms of the body. Furthermore, nanotechnology has provided promising ways for diagnosing and treating cancer in the last decade. The progress in nanoparticle drug carrier development, combined with enhanced understanding of the immune system, has enabled harnessing of anti-tumor immunity. This review focuses on the recent advances in nanotechnology that have improved the therapeutic efficacy of immunotherapies, with emphasis on dendritic cell physiology and its role in presenting antigens and eliciting therapeutic T cell response.

Four distinct immune microenvironment subtypes in gastric adenocarcinoma with special reference to microsatellite instability

Introduction

Programmed death-ligand 1 (PD-L1) can be overexpressed in tumours other than Epstein-Barr virus (EBV)-positive (EBV⁺) or microsatellite instability-high (MSI-H) gastric cancer (GC) subtypes. We aimed to determine the tumour immune microenvironment (TME) classification of GC to better understand tumour-immune interactions and help patient selection for future immunotherapy with special reference to MSI-H.

Methods

Immunohistochemistry (IHC) for PD-L1 and CD8⁺ T cells in three distinct subtypes of GC (43 EBV⁺, 79 MSI-H and 125 EBV^-/MSS) were performed and analysed. In 66 MSI-H GC, mutation counts were compared with PD-L1 expression and survival of the patients.

Results

GC TME divided by PD-L1 IHC and tumour-infiltrating lymphocytes (TIL) measured by intratumoural CD8 density showed: (1) about 40% of GC are type I (PD-L1⁺/TIL⁺) consisting ~70% of MSI-H or EBV⁺ GC, and ~15% of EBV^-/microsatellite stable (MSS) GC patients show the best survival in both disease-free (HR 2.044) and overall survival (HR 1.993); this type would respond to a checkpoint blockade therapy; (2) almost 30% of GC are type II (PD-L1^-/TIL^-) with the worst survival; (3) approximately 10% of GC are type III (PD-L1⁺/TIL^-); and (4) up to 20% are type IV (PD-L1^-/TIL⁺) and, unexpectedly, ~25% of EBV⁺ or MSI-H GC are within this subtype. In MSI-H GC, frequent frameshift mutations were observed in ARID1A, RNF43, NF1, MSH6, BRD3, NCOA3, BCORL1, TNKS2 and NPM1 and the numbers of frameshift mutation correlated significantly with PD-L1 expression (P<0.05).

Discussion

GC can be classified into four TME types based on PD-L1 and TIL, and numbers of frameshift mutation correlate well with PD-L1 expression in MSI-H GC.

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.

Identification of a five B cell-associated gene prognostic and predictive signature for advanced glioma patients harboring immunosuppressive subtype preference

High grade gliomas contribute to most brain tumor mortality. A few studies reported that the immune system affected glioma development, and immune biomarkers helped understand the disease and formulate effective immunotherapy for patients. Currently, no B lymphocyte-based prognostic signature was reported in gliomas. By applying 78 B cell lineage-specific genes, we conducted a whole-genome gene expression analysis in 782 high grade gliomas derived from three independent datasets by Cox regression analysis and risk score method for signature identification, and then used Gene Ontology, Gene Set Enrichment Analysis, and other statistical methods for functional annotations of the signature-defined differences. We developed a five B cell-associated gene signature for prognosis of high grade glioma patients, which is independent of clinicopathological and genetic features. The signature identified high risk patients suitable for chemoradiotherapy, whereas low risk patients should rule out chemotherapy with radiotherapy only. We found that tumors of TCGA Mesenchymal subtype and wild type IDH1 were preferentially stratified to the high risk group, which bore strong immunosuppressive microenvironment, while tumors of TCGA Proneural subtype and mutated IDH1 were significantly accumulated to the low risk group, which exhibited less immunosuppressive state. The five B cell-associated gene signature predicts poor survival of high risk patients bearing strong immunosuppression and helps select optimal therapeutic regimens for glioma patients.

Prognostic significance of tumor-infiltrating immune cells and PD-L1 expression in esophageal squamous cell carcinoma

Programmed death-1 receptor (PD-1) and its ligand (PD-L1) play an integral role in regulating the immune response against cancer. This study investigated the prognostic significance of PD-L1 expression on tumor cells and tumor-infiltrating immune cells (TILs) in the tumor microenvironment in Chinese patients with esophageal squamous cell carcinoma (ESCC). Archival formalin-fixed, paraffin-embedded ESCC samples from treatment-naïve patients with ESCC after surgery or by diagnostic endoscopic biopsy were collected between 2004 and 2014. Expression of PD-L1 in ESCC tumor specimens was assessed by immunohistochemistry (IHC), and the degree of TIL infiltration was evaluated by examining hematoxylin and eosin-stained (H&E) specimens. PD-L1+ as defined as ≥1% of tumor cell membranes showing ≥1+ intensity. In 428 patients, specimens from 341 (79.7%) were PD-L1+. In the definitive treatment group (patients who received curative esophagectomy or definitive [chemo-]radiation therapy), PD-L1 positivity was associated with a significantly shorter DFS and OS. In the palliative chemotherapy group exhibited, neither PFS nor OS correlated significantly with PD-L1 expression. PD-L1 expression was positively associated with TIL density. In 17 paired tumor tissues collected before and after treatment, an increase in PD-L1 expression was associated with disease progression, whereas a decrease in PD-L1 expression was associated with response to chemotherapy or disease control. So, PD-L1 expression was associated with a significantly worse prognosis in patients with ESCC. These observations suggest that PD-L1 may play a critical role in ESCC cancer progression and provide a rationale for developing PD-L1 inhibitors for treatment of a subset of ESCC patients.

SRS in Combination With Ipilimumab: A Promising New Dimension for Treating Melanoma Brain Metastases

Stereotactic radiosurgery provides effective local control, but high recurrence rate are observed while ipilimumab have shown promising improvements in survival in the treatment of melanoma brain metastases. This meta-analysis was done to review the clinical evidence regarding the combination of stereotactic radiosurgery and ipilimumab in the treatment of brain metastases from melanoma. Comprehensive research of the electronic databases (PubMed and Cochrane Library) was carried out in April 2017. Different combination of MESH headings and words were used. Review Manager was used to analyze the outcome data of interest. According to heterogeneity, fixed effects model or random effects model was adapted. Six retrospective studies comparing stereotactic radiosurgery plus ipilimumab with stereotactic radiosurgery alone were found. Total of 411 participants were included in this meta-analysis. Of that, 128 patients had received stereotactic radiosurgery + ipilimumab, while 283 patients had received stereotactic radiosurgery only. Stereotactic radiosurgery plus ipilimumab significantly improved survival when compared to stereotactic radiosurgery alone (hazard ratio: 0.74 [95% confidence interval: 0.56-0.99, P = .04]), with no significant increase in the incidence of adverse events (odds ratio 0.57 [95% confidence interval: 0.28-1.17, P = .12]). Stereotactic radiosurgery with ipilimumab is safe and effective treatment option and can be recommended for the treatment of brain metastases in patients with melanoma.

Low dose irradiation increases adoptive cytotoxic T lymphocyte migration in gastric cancer

Adoptive cellular immunotherapy (ACI) has been demonstrated to be a promising cancer therapeutic; however, the inefficient migration of adoptive immune cells to tumors is one of the rate-limiting factors of ACI. The present study investigated whether 2 Gy low dose irradiation (LDI) was able to increase the migration of adoptive lymphocytes to gastric cancer cells. Treatment with 2 Gy LDI resulted in marked chemokine (C-X-C motif) ligand 9 (CXCL9) and CXCL10 production from gastric cancer cell lines. A Transwell chamber migration assay demonstrated enhanced transmigration of cytotoxic T lymphocytes to gastric cancer cells following LDI treatment. After 2 Gy LDI application to established gastric carcinoma in nude mice, labeled immune cells were infused by intravenous injection and concentrated fluorescence signals were observed at the tumor sites within the mice, with a peak signal at 8-h LDI. Increased numbers of adoptive T cells at the tumor sites were also observed using flow cytometry. Furthermore, a case study of a patient with metastatic gastric cancer who had received ACI treatment combined with 2 Gy LDI provided further evidence that 2 Gy LDI is able to recruit antitumor effector T cells to tumor sites. Therefore, the ability of 2 Gy LDI to convert tumors into inflamed peripheral tissues may be exploited to overcome obstacles at the effector phase of the antitumor immune response and improve the therapeutic efficacy of immunotherapy.

Developing T-cell therapies for lymphoma without receptor engineering

T-cell therapy has emerged from the bench for the treatment of patients with lymphoma. Responses to T-cell therapeutics are regulated by multiple factors, including the patient's immune system status and disease stage. Outside of engineering of chimeric antigen receptors and artificial T-cell receptors, T-cell therapy can be mediated by ex vivo expansion of antigen-specific T cells targeting viral and/or nonviral tumor-associated antigens. These approaches are contributing to enhanced clinical responses and overall survival. In this review, we summarize the available T-cell therapeutics beyond receptor engineering for the treatment of patients with lymphoma.

Developing T-cell therapies for lymphoma without receptor engineering

T-cell therapy has emerged from the bench for the treatment of patients with lymphoma. Responses to T-cell therapeutics are regulated by multiple factors, including the patient's immune system status and disease stage. Outside of engineering of chimeric antigen receptors and artificial T-cell receptors, T-cell therapy can be mediated by ex vivo expansion of antigen-specific T cells targeting viral and/or nonviral tumor-associated antigens. These approaches are contributing to enhanced clinical responses and overall survival. In this review, we summarize the available T-cell therapeutics beyond receptor engineering for the treatment of patients with lymphoma.

Cure in Advanced Renal Cell Cancer: Is It an Achievable Goal?

BACKGROUND

Immunotherapy has historically been of interest in the management of metastatic renal cell cancer (mRCC) because of its relative chemoresistance and the reproducible but low incidence of spontaneous remission in metastatic disease. Recently, targeted immunotherapies in the form of checkpoint inhibitors have shown durable responses in approximately 20%-30% of patients with solid tumors, with a much more acceptable side-effect profile. Anti-programmed death receptor 1 (PD-1)/programmed death receptor ligand 1 antibodies rely on the presence of host T cells in the tumor microenvironment to be stimulated in order to activate an antitumor response. The presence of tumor antigens augments this stimulation. This has led to further research into combination therapy with anti-PD-1 inhibitors and radiotherapy, chemotherapy, or targeted therapy with the aim of increasing the response rate to these agents.

MATERIALS AND METHODS

We describe three cases of patients with mRCC treated with anti-PD-1 antibody therapy in combination with targeted therapy (bevacizumab), anti-cytotoxic T lymphocyte antigen 4 therapy (ipilimumab), or radiotherapy. We perform a comprehensive literature review on combination immunotherapy and the scope for the future.

RESULTS

Two patients had a complete clinical response within 3 months of commencing treatment. The third patient had a further significant response to radiotherapy outside the field of treatment after initial response to anti-PD-1 therapy, which lasted for over 12 months.

CONCLUSION

We are now in the era of immunotherapy with promising results in select patients. However, the number of complete remissions with single agents are low. This report demonstrates the potential for combination therapy in mRCC to produce complete responses and improved survival rates. Whether these results equate to cure in a subset of patients requires longer follow-up. Further evaluation of dosing regimens, sequencing methods, and biomarkers to select patient population is required to advance this treatment strategy.

IMPLICATIONS FOR PRACTICE

Multiple phase I-III studies exploring the benefit of combination immunotherapy are currently under way. Further research into predictive biomarkers to identify the cohort of patients who gain this benefit is pertinent. This case series demonstrates that the combination of immunotherapy with other treatments can lead to complete responses, even in patients with initially bulky disease. Combination therapy with immunotherapy seems to cause more durable responses in patients with metastatic renal cell cancer compared with monotherapy. Significantly longer follow-up is necessary to determine whether durable complete response confers a cure in a select group of patients.

Cell therapies for hematological malignancies: don't forget non-gene-modified t cells!

Cell therapy currently performs an important role in the treatment of patients with various hematological malignancies. The response to the cell therapy is regulated by multiple factors including the patient's immune system status, genetic profile, stage at diagnosis, age, and underlying disease. Cell therapy that does not require genetic manipulation can be mediated by donor lymphocyte infusion strategies, selective depletion in the post-transplant setting and the ex vivo expansion of antigen-specific T cells. For hematologic malignancies, cell therapy is contributing to enhanced clinical responses and overall survival and the immune response to cell therapy is predictive of response in multiple cancer types. In this review we summarize the available T cell therapeutics that do not rely on gene engineering for the treatment of patients with blood cancers.

Analysis of the immune infiltrate in undifferentiated pleomorphic sarcoma of the extremity and trunk in response to radiotherapy: Rationale for combination neoadjuvant immune checkpoint inhibition and radiotherapy

Background: Undifferentiated pleomorphic sarcoma of the extremity and trunk (ET-UPS) presents a unique therapeutic challenge. Although immunotherapy has recently been employed in advanced soft tissue sarcoma, there is limited data characterizing the immune infiltrate in ET-UPS. Radiotherapy (RT) has been shown in other tumor types to promote tumor antigen release and enhance tumor-specific targeting by the adaptive immune system. The aim of this study was to 1) characterize the baseline immune infiltrate and 2) evaluate the effect of preoperative RT on the histologic appearance of and the immune infiltrate in ET-UPS. Methods: We identified 17 matched ET-UPS samples before and after RT. Immunohistochemistry was performed with CD8, CD4, PD-L1, PD1, CD3, CD163 and FoxP3 positive cells identified in all samples. Changes in the immune infiltrate following RT were examined. Results: There was a trend towards increased density of tumor infiltrating immune cells in ET-UPS following RT, with increases in median number of CD3 (158 vs 219 cells/mm2, p = 0.06), CD4 (3 vs 13 cells/mm2, p = 0.01), CD8 (55 vs 111 cells/mm2, p = 0.17), and FOXP3 (14 vs 25 cells/mm2, p = 0.23) positive cells. Interestingly, although PD-L1 was not expressed in any ET-UPS tumor at baseline, positive PD-L1 expression was observed in 21% (3/14) of tumors after RT (p = 0.07). Conclusion: An immune infiltrate is present in ET-UPS at the time of diagnosis, with a trend towards increased density of immune infiltrate and PD-L1 expression after RT. These data support prospectively evaluating immune checkpoint inhibitors with standard of care RT in the treatment of ET-UPS.