Radiation and immunotherapy: a synergistic combination

PRECISE: Preoperative Radiation Therapy to Elicit Critical Immune Stimulating Effects - A Phase 2 Clinical Trial

PURPOSE

Radiation therapy is an underinvestigated tool for priming the immune system in intact human breast cancers. We sought here to investigate if a preoperative radiation therapy boost delivered was associated with a significant change in tumor-infiltrating lymphocytes (TILs) in the tumor in estrogen receptor positive, HER2Neu nonamplified breast cancers.

METHODS AND MATERIALS

A total of 20 patients were enrolled in a phase 2 clinical trial and received either 7.5 Gy × 1 fraction or 2 Gy × 5 fractions, completed 6 to 8 days before surgery. Percent stromal TILs were evaluated on hematoxylin and eosin-stained samples. Short-term safety was assessed based on time to surgery, toxicities, and cosmesis up to 6 months after boost.

RESULTS

Stromal TIL increased 6 to 8 days after completion of boost radiation therapy (median 3.0 [IQR, 1.0-6.5]) before radiation therapy versus median 5.0 (IQR, 1.5-8.0) after radiation therapy, P = .0037. Zero grade ≥3 toxicities up to 6 months after boost were experienced. In all, 94% (16/17) patients with 6-month follow-up cosmetic assessment after breast conservation had good-excellent cosmesis by physician assessment.

CONCLUSION

In this phase 2 trial, preoperative radiation therapy boost resulted in a short-term increase in stromal TIL with minimal toxicities. Preoperative breast radiation therapy appears to be safe and may be a feasible means for priming the tumor microenvironment.

Novel time-synchronized immune-guided partial tumor irradiation: Proof of principle trial

BACKGROUND AND PURPOSE

Radiotherapy for bulky tumors often results in palliation with suboptimal outcomes. The prognosis is worsened by immunosuppression caused by radio-chemotherapy, negatively impacting on survival. Novel Partial Tumor Irradiation (PTI) was designed to spare the Peritumoral Immune Microenvironment (PIM) and to be delivered synchronously with immune activity peaks, thus enhancing both local and distant tumor control through immunostimulation.

MATERIALS AND METHODS

Present proof-of-principle trial enrolled 26 patients with bulky tumors, comparing outcomes between treatments administered at immune activity peaks versus troughs. The primary endpoint was local-bystander and distal-abscopal response-rate. Secondary endpoints included overall-, progression-free-, cancer-specific survival, neoadjuvant and immunomodulatory potential.

RESULTS

All measured outcomes were significantly influenced by treatment-timing. The bystander and abscopal response rates were 77% and 41%, respectively. PTI significantly upregulated pro-inflammatory and cell-death-inducing pathways improving the efficacy of radiotherapy by highly complex tumors.

CONCLUSIONS

This study highlights the profound impact PTI can have on a highly palliative patient cohort previously deemed beyond therapeutic hope. With 41 % of these patients still alive after a median follow-up of 50 months, PTI offers a potential lifeline for those facing advanced, treatment-resistant cancers. This approach generated also distant immunogenic anti-tumor responses, offering a promising new avenue for the treatment of advanced cancers.

Mechanistic in silico explorations of the immunogenic and synergistic effects of radiotherapy and immunotherapy: a critical review

Immunotherapy is a rapidly evolving field, with many models attempting to describe its impact on the immune system, especially when paired with radiotherapy. Tumor response to this combination involves a complex spatiotemporal dynamic which makes either clinical or pre-clinical in vivo investigation across the resulting extensive solution space extremely difficult. In this review, several in silico models of the interaction between radiotherapy, immunotherapy, and the patient's immune system are examined. The study included only mathematical models published in English that investigated the effects of radiotherapy on the immune system, or the effect of immuno-radiotherapy with immune checkpoint inhibitors. The findings indicate that treatment efficacy was predicted to improve when both radiotherapy and immunotherapy were administered, compared to radiotherapy or immunotherapy alone. However, the models do not agree on the optimal schedule and fractionation of radiotherapy and immunotherapy. This corresponds to relevant clinical trials, which report an improved treatment efficacy with combination therapy, however, the optimal scheduling varies between clinical trials. This discrepancy between the models can be attributed to the variation in model approach and the specific cancer types modeled, making the determination of the optimum general treatment schedule and model challenging. Further research needs to be conducted with similar data sets to evaluate the best model and treatment schedule for a specific cancer type and stage.

Cancer stem cells: advances in knowledge and implications for cancer therapy

Cancer stem cells (CSCs), a small subset of cells in tumors that are characterized by self-renewal and continuous proliferation, lead to tumorigenesis, metastasis, and maintain tumor heterogeneity. Cancer continues to be a significant global disease burden. In the past, surgery, radiotherapy, and chemotherapy were the main cancer treatments. The technology of cancer treatments continues to develop and advance, and the emergence of targeted therapy, and immunotherapy provides more options for patients to a certain extent. However, the limitations of efficacy and treatment resistance are still inevitable. Our review begins with a brief introduction of the historical discoveries, original hypotheses, and pathways that regulate CSCs, such as WNT/β-Catenin, hedgehog, Notch, NF-κB, JAK/STAT, TGF-β, PI3K/AKT, PPAR pathway, and their crosstalk. We focus on the role of CSCs in various therapeutic outcomes and resistance, including how the treatments affect the content of CSCs and the alteration of related molecules, CSCs-mediated therapeutic resistance, and the clinical value of targeting CSCs in patients with refractory, progressed or advanced tumors. In summary, CSCs affect therapeutic efficacy, and the treatment method of targeting CSCs is still difficult to determine. Clarifying regulatory mechanisms and targeting biomarkers of CSCs is currently the mainstream idea.

Contribution of Enhanced Locoregional Control to Improved Overall Survival with Consolidative Durvalumab after Concurrent Chemoradiotherapy in Locally Advanced Non-Small Cell Lung Cancer: Insights from Real-World Data

PURPOSE

This study aimed to assess the real-world clinical outcomes of consolidative durvalumab in patients with unresectable locally advanced non-small cell lung cancer (LA-NSCLC) and to explore the role of radiotherapy in the era of immunotherapy.

MATERIALS AND METHODS

This retrospective study assessed 171 patients with unresectable LA-NSCLC who underwent concurrent chemoradiotherapy (CCRT) with or without consolidative durvalumab at Asan Medical Center between May 2018 and May 2021. Primary outcomes included freedom from locoregional failure (FFLRF), distant metastasis-free survival (DMFS), progression-free survival (PFS), and overall survival (OS).

RESULTS

Durvalumab following CCRT demonstrated a prolonged median PFS of 20.9 months (p=0.048) and a 3-year FFLRF rate of 57.3% (p=0.008), compared to 13.7 months and 38.8%, respectively, with CCRT alone. Furthermore, the incidence of in-field recurrence was significantly greater in the CCRT-alone group compared to the durvalumab group (26.8% vs. 12.4%, p=0.027). While median OS was not reached with durvalumab, it was 35.4 months in patients receiving CCRT alone (p=0.010). Patients positive for programmed cell death ligand 1 (PD-L1) expression showed notably better outcomes, including FFLRF, DMFS, PFS, and OS. Adherence to PACIFIC trial eligibility criteria identified 100 patients (58.5%) as ineligible. The use of durvalumab demonstrated better survival regardless of eligibility criteria.

CONCLUSION

The use of durvalumab consolidation following CCRT significantly enhanced locoregional control and OS in patients with unresectable LA-NSCLC, especially in those with PD-L1-positive tumors, thereby validating the role of durvalumab in standard care.

A Novel Translational PET Imaging Approach to Quantifying Distal Tumor Immune Activation After Targeted Radiation Therapy and Checkpoint Blockade

PURPOSE

This study aimed to provide a novel noninvasive method to quantify abscopal immune activation and predict combinational treatment response using [68Ga]-NOTA-GZP positron emission tomography (PET) imaging.

METHODS AND MATERIALS

4T1 breast cancer cells were implanted bilaterally in the mammary fat pad of Balb/c mice and Lewis's lung cancer cells (LLC) were implanted bilaterally on the shoulders of C57/Bl6 mice. One of the tumors received a single fraction of 12 Gy irradiation followed by combination of concurrent PD-1 and CTLA-4 inhibitors or controls. Tumor growth of the irradiated and nonirradiated tumors was measured and compared with 12 Gy irradiation only, checkpoint inhibitor only, and no treatment control group. Changes in granzyme B activity were assessed with [68Ga]-NOTA-GZP PET imaging from baseline and every 3 days until day 9.

RESULTS

In the 4T1 model, concurrent treatment with dual checkpoint inhibitors and radiation resulted in reduction of the irradiated tumor volume at day 30. At this same time point, the nonirradiated tumor volume for combination treatment decreased significantly, consistent with abscopal immune activation. Similarly, in the LLC model, concurrent treatment inhibited tumor growth on the nonirradiated tumor at day 15. On day 9, granzyme B PET signal in both 4T1 and LLC models was significantly higher in the nonirradiated tumors that responded to concurrent treatment compared with subsequent nonresponding tumors. A similar lack of granzyme B signal was observed in the nonirradiated tumors from mice that received radiation or checkpoint inhibitors only and control tumors. Receiver operating characteristic analysis identified a PET threshold of 1.505 and 1.233 on day 9 that predicted treatment response in 4T1 and LLC models, respectively.

CONCLUSIONS

[68Ga]-NOTA-GZP PET imaging was able to noninvasively predict abscopal immune activation before subsequent tumor volume changes after combination treatment. It provides a potential translational paradigm for investigating distal immune activation postradiation in a clinical setting.

Efficacy and safety analysis of immune checkpoint inhibitor rechallenge therapy in locally advanced and advanced non-small cell lung cancer: a retrospective study

Background

Immune checkpoint inhibitors (ICIs) have dramatically changed the first-line treatment pattern of non-small cell lung cancer (NSCLC) without driver gene alterations. However, the optimal choice for second-line treatment after initial treatment with ICIs is unclear. This study aimed to clarify the efficacy and safety of ICI rechallenge therapy in locally advanced and advanced NSCLC.

Methods

We retrospectively analyzed the histories of 224 patients with locally advanced or advanced NSCLC treated with programmed death-1 (PD-1)/programmed death-ligand 1 (PD-L1) inhibitors alone or in combination with chemotherapy and/or antiangiogenic therapy in first-line treatment. Progression-free survival 2 (PFS2) was the time from the first defined progress disease (PD) to the second disease progression or death. Efficacy evaluation was performed directly in accordance with RECIST v1.1 criteria. Adverse events (AEs) were graded following the National Cancer Institute Common Terminology Criteria for Adverse Events v5.0. Survival data were estimated using the Kaplan-Meier method or Cox survival regression model and compared using the log-rank test in overall cohort and other subgroups.

Results

There were no significant differences in objective response rate (ORR) and median PFS2 (mPFS2) between the ICI rechallenge group and non-rechallenge group (ORR: 10.3% vs. 15.3%, P=0.308; mPFS2: 5.33 vs. 4.40 months, P=0.715). And the ICI rechallenge group showed no new safety signals compared with non-rechallenge group. In ICI rechallenge group, patients resistant to first-line immunotherapy had a lower ORR and shorter PFS2 compared with those who responded to initial ICIs treatment (ORR: 7.0% vs. 17.6%, P=0.038; mPFS2: 3.68 vs. 5.91 months, P=0.014). No significant difference in mPFS2 was observed among different second-line treatment groups (P=0.362). Radiotherapy in second-line treatment and ICI rechallenge therapy were not the main factors affecting PFS2.

Conclusions

ICI rechallenge therapy beyond disease progression did not improve clinical outcomes in patients with NSCLC, but no new safety signals emerged. However, patients with favorable response to initial ICIs treatment still showed significant efficacy of subsequent ICI rechallenge therapy.

Molecular Changes in Breast Cancer Induced by Radiation Therapy

PURPOSE

Breast cancer treatments are based on prognostic clinicopathologic features that form the basis for therapeutic guidelines. Although the utilization of these guidelines has decreased breast cancer-associated mortality rates over the past three decades, they are not adequate for individualized therapy. Radiation therapy (RT) is the backbone of breast cancer treatment. Although a highly successful therapeutic modality clinically, from a biological perspective, preclinical studies have shown RT to have the potential to alter tumor cell phenotype, immunogenicity, and the surrounding microenvironment, potentially changing the behavior of cancer cells and resulting in a significant variation in RT response. This review presents the recent advances in revealing the complex molecular changes induced by RT in the treatment of breast cancer and highlights the complexities of translating this information into clinically relevant tools for improved prognostic insights and the revelation of novel approaches for optimizing RT.

METHODS AND MATERIALS

Current literature was reviewed with a focus on recent advances made in the elucidation of tumor-associated radiation-induced molecular changes across molecular, genetic, and proteomic bases. This review was structured with the aim of providing an up-to-date overview over the very broad and complex subject matter of radiation-induced molecular changes and radioresistance, familiarizing the reader with the broader issue at hand.

RESULTS

The subject of radiation-induced molecular changes in breast cancer has been broached from various physiological focal points including that of the immune system, immunogenicity and the abscopal effect, tumor hypoxia, breast cancer classification and subtyping, molecular heterogeneity, and molecular plasticity. It is becoming increasingly apparent that breast cancer clinical subtyping alone does not adequately account for variation in RT response or radioresistance. Multiple components of the tumor microenvironment and immune system, delivered RT dose and fractionation schedules, radiation-induced bystander effects, and intrinsic tumor physiology and heterogeneity all contribute to the resultant RT outcome.

CONCLUSIONS

Despite recent advances and improvements in anticancer therapies, tumor resistance remains a significant challenge. As new analytical techniques and technologies continue to provide crucial insight into the complex molecular mechanisms of breast cancer and its treatment responses, it is becoming more evident that personalized anticancer treatment regimens may be vital in overcoming radioresistance.

Modeling the Synergistic Impact of Yttrium 90 Radioembolization and Immune Checkpoint Inhibitors on Hepatocellular Carcinoma

The impact of yttrium 90 radioembolization (Y90-RE) in combination with immune checkpoint inhibitors (ICIs) has recently gained attention. However, it is unclear how sequencing and dosage affect therapeutic efficacy. The purpose of this study was to develop a mathematical model to simulate the synergistic effects of Y90-RE and ICI combination therapy and find the optimal treatment sequences and dosages. We generated a hypothetical patient cohort and conducted simulations to apply different treatments to the same patient. The compartment of models is described with ordinary differential equations (ODEs), which represent targeted tumors, non-targeted tumors, and lymphocytes. We considered Y90-RE as a local treatment and ICIs as a systemic treatment. The model simulations show that Y90-RE and ICIs administered simultaneously yield greater benefits than subsequent sequential therapy. In addition, applying Y90-RE before ICIs has more benefits than applying ICIs before Y90-RE. Moreover, we also observed that the median PFS increased up to 31~36 months, and the DM rates at 3 years decreased up to 36~48% as the dosage of the two drugs increased (p < 0.05). The proposed model predicts a significant benefit of Y90-RE with ICIs from the results of the reduced irradiated tumor burden and the associated immune activation and suppression. Our model is expected to help optimize complex strategies and predict the efficacy of clinical trials for HCC patients.

CX3CR1-Expressing Immune Cells Infiltrate the Tumor Microenvironment and Promote Radiation Resistance in a Mouse Model of Lung Cancer

INTRODUCTION

Chemokine (C-X3-C Motif) Receptor 1 (CX3CR1) is present in a subset of the immune cells in the tumor microenvironment (TME) and plays an essential and diverse role in cancer progression. However, its potential function in the irradiated TME remains unknown.

MATERIALS AND METHODS

A mouse lung cancer model was performed by subcutaneously inoculating Lewis Lung Carcinoma (LLC) cells expressing luciferase (Luc-2) and mCherry cells in CX3CR1GFP/GFP, CX3CR1DTR/+, and wild-type (WT) mice. Bioluminescence imaging, clonogenic assay, and flow cytometry were used to assess tumor progression, proliferation, and cell composition after radiation.

RESULTS

Radiation provoked a significant influx of CX3CR1-expressing immune cells, notably monocytes and macrophages, into the TME. Co-culturing irradiated LLC cells with CX3CR1-deficient monocytes, and macrophages resulted in reduced clonogenic survival and increased apoptosis of the cancer cells. Interestingly, deficiency of CX3CR1 in macrophages led to a redistribution of the irradiated LLC cells in the S-phase, parallel to increased expression of cyclin E1, required for cell cycle G1/S transition. In addition, the deficiency of CX3CR1 expression in macrophages altered the cytokine secretion with a decrease in interleukin 6, a crucial mediator of cancer cell survival and proliferation. Next, LLC cells were injected subcutaneously into CX3CR1DTR/+ mice, sensitive to diphtheria toxin (DT), and WT mice. After injection, tumors were irradiated with 8 Gy, and mice were treated with DT, leading to conditional ablation of CX3CR1-expressing cells. After three weeks, CX3CR1-depleted mice displayed reduced tumor progression. Furthermore, combining the S-phase-specific chemotherapeutic gemcitabine with CX3CR1 cell ablation resulted in additional attenuation of tumor progression.

CONCLUSIONS

CX3CR1-expressing mononuclear cells invade the TME after radiation therapy in a mouse lung cancer model. CX3CR1 cell depletion attenuates tumor progression following radiation and sensitizes the tumor to S-phase-specific chemotherapy. Thus, we propose a novel strategy to improve radiation sensitivity by targeting the CX3CR1-expressing immune cells.

The prognostic and biology of tumour-infiltrating lymphocytes in the immunotherapy of cancer

Tumour immunotherapy has achieved remarkable clinical success in many different types of cancer in the past two decades. The outcome of immune checkpoint inhibitors in cancer patients has been linked to the quality and magnitude of T cell, NK cell, and more recently, B cell within the tumour microenvironment, suggesting that the immune landscape of a tumour is highly connected to patient response and prognosis. It is critical to understanding tumour immune microenvironments for identifying immune modifiers of cancer progression and developing cancer immunotherapies. The infiltration of solid tumours by immune cells with anti-tumour activity is both a strong prognostic factor and a therapeutic goal. Recent approaches and applications of new technologies, especially single-cell mRNA analysis in dissecting tumour microenvironments have brought important insights into the biology of tumour-infiltrating immune cells, revealed a remarkable degree of cellular heterogeneity and distinct patterns of immune response. In this review, we will discuss recent advances in the understanding of tumour infiltrated lymphocytes, their prognostic benefit, and predictive value for immunotherapy.

Ultrahypofractionated Low-Dose Total Skin Electron Beam in Advanced-Stage Mycosis Fungoides and Sézary Syndrome

PURPOSE

The aim of this study was to assess the safety and efficacy of an ultrahypofractionated low-dose total skin electron beam therapy (TSEBT) regimen in patients with advanced mycosis fungoides (MF) or Sézary syndrome (SS).

METHODS AND MATERIALS

In this multicenter observational study from 5 German centers, 18 total patients with MF or SS underwent TSEBT with a total dose of 8 Gy in 2 fractions. The primary endpoint was the overall response rate.

RESULTS

Fifteen of 18 patients with stage IIB-IV MF or SS were heavily pretreated with a median of 4 prior systemic therapies. The overall response rate was 88.9% (95% confidence interval [CI], 65.3-98.6), with 3 complete responses (16.9%; 95% CI, 3.6-41.4). At a median follow-up period of 13 months, the median time to next treatment (TTNT) was 12 months (95% CI, 8.2-15.8), and the median progression-free survival was 8 months (95% CI, 2-14). A significant reduction in the modified severity-weighted assessment tool, total Skindex-29 score (Bonferroni-corrected P < .005), and all subdomains (Bonferroni-corrected P < .05) was observed after TSEBT. Half of the irradiated patients (n = 9) developed grade 2 acute and subacute toxicities. One patient had confirmed grade 3 acute toxicity. Chronic grade 1 toxicity has been observed in 33% of patients. Patients with erythroderma/SS or prior radiation therapy appear at higher risk of skin toxicities.

CONCLUSIONS

TSEBT with 8 Gy in 2 fractions achieves good disease control and symptom palliation with acceptable toxicity, greater convenience, and fewer hospital visits.

A review on lymphocyte radiosensitivity and its impact on radiotherapy

It is well known that radiation therapy causes lymphopenia in patients and that this is correlated with a negative outcome. The mechanism is not well understood because radiation can have both immunostimulatory and immunosuppressive effects. How tumor dose conformation, dose fractionation, and selective lymph node irradiation in radiation therapy does affect lymphopenia and immune response is an active area of research. In addition, understanding the impact of radiation on the immune system is important for the design and interpretation of clinical trials combining radiation with immune checkpoint inhibitors, both in terms of radiation dose and treatment schedules. Although only a few percent of the total lymphocyte population are circulating, it has been speculated that their increased radiosensitivity may contribute to, or even be the primary cause of, lymphopenia. This review summarizes published data on lymphocyte radiosensitivity based on human, small animal, and in vitro studies. The data indicate differences in radiosensitivity among lymphocyte subpopulations that affect their relative contribution and thus the dynamics of the immune response. In general, B cells appear to be more radiosensitive than T cells and NK cells appear to be the most resistant. However, the reported dose-response data suggest that in the context of lymphopenia in patients, aspects other than cell death must also be considered. Not only absolute lymphocyte counts, but also lymphocyte diversity and activity are likely to be affected by radiation. Taken together, the reviewed data suggest that it is unlikely that radiation-induced cell death in lymphocytes is the sole factor in radiation-induced lymphopenia.

Combined radiotherapy and immune checkpoint inhibition for the treatment of advanced hepatocellular carcinoma

Hepatocellular Carcinoma (HCC) is one of the most common cancers and a leading cause of cancer related death worldwide. Until recently, systemic therapy for advanced HCC, defined as Barcelona Clinic Liver Cancer (BCLC) stage B or C, was limited and ineffective in terms of long-term survival. However, over the past decade, immune check point inhibitors (ICI) combinations have emerged as a potential therapeutic option for patients with nonresectable disease. ICI modulate the tumor microenvironment to prevent progression of the tumor. Radiotherapy is a crucial tool in treating unresectable HCC and may enhance the efficacy of ICI by manipulating the tumor microenvironment and decreasing tumor resistance to certain therapies. We herein review developments in the field of ICI combined with radiotherapy for the treatment of HCC, as well as look at challenges associated with these treatment modalities, and review future directions of combination therapy.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Immune microenvironment remodeling after radiation of a progressing brain metastasis

Radiation is commonly used in the treatment of many cancers. However, its effects on anti-tumor immune responses are incompletely understood. Here, we present a detailed immunological analysis of two tumors from a patient with multiple non-small cell lung cancer metastases to the brain. One tumor was resected without treatment; the second was irradiated to a total dose of 30 Gy and resected following further progression. Comprehensive single-cell analysis reveals a substantially reduced immune cell fraction in the irradiated tumor, including the depletion of tissue-resident macrophages and infiltration of pro-inflammatory monocytes. Despite the presence of similar somatic mutations in both tumors, radiation is associated with the depletion of exhausted, tumor-resident T cell clones and their replacement by circulating clones unlikely to contribute to tumor-specific immunity. These results provide insight into the local effects of radiation on anti-tumor immunity and raise important considerations for the combination of radiation and immunotherapy.

A Mathematical Model for Predicting Patient Responses to Combined Radiotherapy with CTLA-4 Immune Checkpoint Inhibitors

The purpose of this study was to develop a cell-cell interaction model that could predict a tumor's response to radiotherapy (RT) combined with CTLA-4 immune checkpoint inhibition (ICI) in patients with hepatocellular carcinoma (HCC). The previously developed model was extended by adding a new term representing tremelimumab, an inhibitor of CTLA-4. The distribution of the new immune activation term was derived from the results of a clinical trial for tremelimumab monotherapy (NCT01008358). The proposed model successfully reproduced longitudinal tumor diameter changes in HCC patients treated with tremelimumab (complete response = 0%, partial response = 17.6%, stable disease = 58.8%, and progressive disease = 23.6%). For the non-irradiated tumor control group, adding ICI to RT increased the clinical benefit rate from 8% to 32%. The simulation predicts that it is beneficial to start CTLA-4 blockade before RT in terms of treatment sequences. We developed a mathematical model that can predict the response of patients to the combined CTLA-4 blockade with radiation therapy. We anticipate that the developed model will be helpful for designing clinical trials with the ultimate aim of maximizing the efficacy of ICI-RT combination therapy.

Application of nano-radiosensitizers in combination cancer therapy

Radiosensitizers are compounds or nanostructures, which can improve the efficiency of ionizing radiation to kill cells. Radiosensitization increases the susceptibility of cancer cells to radiation-induced killing, while simultaneously reducing the potentially damaging effect on the cellular structure and function of the surrounding healthy tissues. Therefore, radiosensitizers are therapeutic agents used to boost the effectiveness of radiation treatment. The complexity and heterogeneity of cancer, and the multifactorial nature of its pathophysiology has led to many approaches to treatment. The effectiveness of each approach has been proven to some extent, but no definitive treatment to eradicate cancer has been discovered. The current review discusses a broad range of nano-radiosensitizers, summarizing possible combinations of radiosensitizing NPs with several other types of cancer therapy options, focusing on the benefits and drawbacks, challenges, and future prospects.

Relationship between the tumor microenvironment and the efficacy of the combination of radiotherapy and immunotherapy

Activating and recruiting the immune system is critical for successful cancer treatment. Since the discovery of immune checkpoint inhibitors, immunotherapy has become the standard of care for many types of cancers. However, many patients fail to respond to immunotherapy. Further research is needed to understand the mechanisms of resistance and adjuvant therapies that can help sensitize patients to immunotherapies. Here, we will discuss how radiotherapy can change the tumor microenvironment and work synergistically with immunotherapy. We will examine different pre-clinical models focusing on their limitations and their unique advantages in studying the efficacy of treatments and the tumor microenvironment. We will also describe emerging findings from clinical trials testing the combination of immunotherapy and radiotherapy.

Radiation-assisted strategies provide new perspectives to improve the nanoparticle delivery to tumor

Nanoparticles (NPs), with advantages in tumor targeting, have been extensively developed for anticancer treatment. However, the delivery efficacy of NPs tends to be heterogeneous in clinical research. Surprisingly, a traditional cancer treatment, radiotherapy (radiation), has been observed with the potential to improve the delivery of NPs by influencing the features of the tumor microenvironment, which provides new perspectives to overcome the barriers in the NPs delivery. Since the effect of radiation can also be enhanced by versatile NPs, these findings of radiation-assisted NPs delivery suggest innovative strategies combining radiotherapy with nanotherapeutics. This review summarizes the research on the delivery and therapeutic efficacy of NPs that are improved by radiation, focusing on relative mechanisms and existing challenges and opportunities.

Syngeneic N1-S1 Orthotopic Hepatocellular Carcinoma in Sprague Dawley Rat for the Development of Interventional Oncology-Based Immunotherapy: Survival Assay and Tumor Immune Microenvironment

Rodent HCC rat models provide advantages for interventional oncology (IO) based immunotherapy research compared to other established larger animal models or mice models. Rapid and predictable tumor growth and affordable costs permit the formation of a compelling preclinical model investigating novel IO catheter-directed therapies and local ablation therapies. Among orthotopic HCC models, the N1-S1 orthotopic HCC model has been involved in many research cases. Suboptimal tumor induction rates and potential spontaneous regression during tumor implantation procedures discouraged the use of the N1-S1 HCC model in IO-based immunotherapies. Here, N1-S1 HCC models were generated with a subcapsular implantation of two different number of N1-S1 cells using a mini-laporatomy. Tumor growth assay and immunological profiles which can preclinically evaluate the therapeutic efficacy of IO-based immunotherapy, were characterized. Finally, an N1-S1 HCC rat model generated with the proposed procedure demonstrated a representative immune suppressive HCC tumor environment without self-tumor regression. The optimized syngeneic N1-S1 HCC rat models represent an essential tool for pre-clinical evaluation of new IO immunotherapies for the treatment of HCC.

Wnt/β-Catenin Signaling and Resistance to Immune Checkpoint Inhibitors: From Non-Small-Cell Lung Cancer to Other Cancers

Lung cancer is the leading cause of cancer-related deaths worldwide. The standard of care for advanced non-small-cell lung cancer (NSCLC) without driver-gene mutations is a combination of an anti-PD-1/PD-L1 antibody and chemotherapy, or an anti-PD-1/PD-L1 antibody and an anti-CTLA-4 antibody with or without chemotherapy. Although there were fewer cases of disease progression in the early stages of combination treatment than with anti-PD-1/PD-L1 antibodies alone, only approximately half of the patients had a long-term response. Therefore, it is necessary to elucidate the mechanisms of resistance to immune checkpoint inhibitors. Recent reports of such mechanisms include reduced cancer-cell immunogenicity, loss of major histocompatibility complex, dysfunctional tumor-intrinsic interferon-γ signaling, and oncogenic signaling leading to immunoediting. Among these, the Wnt/β-catenin pathway is a notable potential mechanism of immune escape and resistance to immune checkpoint inhibitors. In this review, we will summarize findings on these resistance mechanisms in NSCLC and other cancers, focusing on Wnt/β-catenin signaling. First, we will review the molecular biology of Wnt/β-catenin signaling, then discuss how it can induce immunoediting and resistance to immune checkpoint inhibitors. We will also describe other various mechanisms of immune-checkpoint-inhibitor resistance. Finally, we will propose therapeutic approaches to overcome these mechanisms.

Neoadjuvant Radiation Therapy and Surgery Improves Metastasis-Free Survival over Surgery Alone in a Primary Mouse Model of Soft Tissue Sarcoma

This study aims to investigate whether adding neoadjuvant radiotherapy (RT), anti-programmed cell death protein-1 (PD-1) antibody (anti-PD-1), or RT + anti-PD-1 to surgical resection improves disease-free survival for mice with soft tissue sarcomas (STS). We generated a high mutational load primary mouse model of STS by intramuscular injection of adenovirus expressing Cas9 and guide RNA targeting Trp53 and intramuscular injection of 3-methylcholanthrene (MCA) into the gastrocnemius muscle of wild-type mice (p53/MCA model). We randomized tumor-bearing mice to receive isotype control or anti-PD-1 antibody with or without radiotherapy (20 Gy), followed by hind limb amputation. We used micro-CT to detect lung metastases with high spatial resolution, which was confirmed by histology. We investigated whether sarcoma metastasis was regulated by immunosurveillance by lymphocytes or tumor cell-intrinsic mechanisms. Compared with surgery with isotype control antibody, the combination of anti-PD-1, radiotherapy, and surgery improved local recurrence-free survival (P = 0.035) and disease-free survival (P = 0.005), but not metastasis-free survival. Mice treated with radiotherapy, but not anti-PD-1, showed significantly improved local recurrence-free survival and metastasis-free survival over surgery alone (P = 0.043 and P = 0.007, respectively). The overall metastasis rate was low (∼12%) in the p53/MCA sarcoma model, which limited the power to detect further improvement in metastasis-free survival with addition of anti-PD-1 therapy. Tail vein injections of sarcoma cells into immunocompetent mice suggested that impaired metastasis was due to inability of sarcoma cells to grow in the lungs rather than a consequence of immunosurveillance. In conclusion, neoadjuvant radiotherapy improves metastasis-free survival after surgery in a primary model of STS.

Potential predictors of immunotherapy in small cell lung cancer

Lung cancer is one of the leading causes of cancer-related deaths worldwide, with small cell lung cancer (SCLC) having the worst prognosis. SCLC is diagnosed late in the disease's progression, limiting treatment options. The most common treatment for SCLC is chemotherapy. As the disease progresses, immunotherapy, most commonly checkpoint inhibitor medication, becomes more important. Efforts should be made in the development of immunotherapy to map specific biomarkers, which play a role in properly assigning a type of immunotherapy to the right cohort of patients, where the benefits outweigh any risks or adverse effects. The objective of this review was to provide a thorough assessment of current knowledge about the nature of the tumor process and treatment options for small cell lung cancer, with a focus on predictive biomarkers. According to the information obtained, the greatest potential, which has already been directly demonstrated in some studies, has characteristics such as tumor microenvironment composition, tumor mutation burden, and molecular subtyping of SCLC. Several other aspects appear to be promising, but more research, particularly prospective studies on a larger number of probands, is required. However, it is clear that this field of study will continue to expand, as developing a reliable method to predict immunotherapy response is a very appealing goal of current medicine and research in the field of targeted cancer therapy.

Prospective Evaluation of Immune Activation Associated with Response to Radioembolization Assessed with PET/CT in Women with Breast Cancer Liver Metastasis

Background The impact of transarterial radioembolization (TARE) of breast cancer liver metastasis (BCLM) on antitumor immunity is unknown, which hinders the optimal selection of candidates for TARE. Purpose To determine whether response to TARE at PET/CT in participants with BCLM is associated with specific immune markers (cytokines and immune cell populations). Materials and Methods This prospective pilot study enrolled 23 women with BCLM who planned to undergo TARE (June 2018 to February 2020). Peripheral blood and liver tumor biopsies were collected at baseline and 1-2 months after TARE. Monocyte, myeloid-derived suppressor cell (MDSC), interleukin (IL), and tumor-infiltrating lymphocyte (TIL) levels were assessed with use of gene expression studies and flow cytometry, and immune checkpoint and cell surface marker levels with immunohistochemistry. Modified PET Response Criteria in Solid Tumors was used to determine complete response (CR) in treated tissue. After log-transformation, immune marker levels before and after TARE were compared using paired t tests. Association with CR was assessed with Wilcoxon rank-sum or unpaired t tests. Results Twenty women were included. After TARE, peripheral IL-6 (geometric mean, 1.0 vs 1.6 pg/mL; P = .02), IL-10 (0.2 vs 0.4 pg/mL; P = .001), and IL-15 (1.9 vs 2.4 pg/mL; P = .01) increased. In biopsy tissue, lymphocyte activation gene 3-positive CD4+ TILs (15% vs 31%; P < .001) increased. Eight of 20 participants (40% [exact 95% CI: 19, 64]) achieved CR. Participants with CR had lower baseline peripheral monocytes (10% vs 29%; P < .001) and MDSCs (1% vs 5%; P < .001) and higher programmed cell death protein (PD) 1-positive CD4+ TILs (59% vs 26%; P = .006) at flow cytometry and higher PD-1+ staining in tumor (2% vs 1%; P = .046). Conclusion Complete response to transarterial radioembolization was associated with lower baseline cytokine, monocyte, and myeloid-derived suppressor cell levels and higher programmed cell death protein 1-positive tumor-infiltrating lymphocyte levels. © RSNA, 2022 Online supplemental material is available for this article.

On target methods to induce abscopal phenomenon for Off‐Target effects: From happenstance to happenings

Although the "abscopal phenomenon" has been described several decades ago, this phenomenon lately has been obtaining momentous traction with the dawn of immune-based therapies. There has been increased cross talk among radiation oncologists, oncologists and immunologists and consequently a surge in the number of prospective clinical trials. This must be coupled with translation work from these clinical trials to aid in eventual identification of patients who may benefit. Abscopal effects may be induced by local and systemic methods, conventional radiotherapy, particle radiation, radionucleotide methods, cryoablation and brachytherapy. These approaches have all been reported to be stimulate abscopal effect. Immune induction by immune checkpoint therapy, immune adjuvants, cellular therapy including CAR and NK cell therapies may generate systemic abscopal response. With increasing recognition of this effect, there remains a lot of work to explore the modalities of inducing abscopal responses and ultimate prediction or prognostication on stratifying who may benefit. Ultimately, there is an urgent need for prospective studies and data to tease apart which one of these modalities can be applied to the appropriate candidate, to the appropriate cancer at the appropriate setting. This review seeks to elucidate readers on the different modalities of radiation, systemic therapies and other techniques rarely explored to potentiate the abscopal effect from a mere coincidence to a finite occurrence.

Systemic benefit of radiation therapy via abscopal effect

Evidence of a systemic response related to localized radiation therapy (RT) in cancer management is rare. However, enhancing the immune response via immunotherapy followed by localized RT has shown evidence of tumor shrinkage to non-irradiated metastatic disease thereby inducing an "abscopal effect." Combined induction of the cGAS-STING pathway and activation of IFN-gamma signaling cascade related to RT within an activated immune environment promotes neoantigen presentation and expansion of cytotoxic effector cells enabling enhancement of systemic immune response. A proposed mechanism, case examples, and clinical trial evidence of "abscopal effect" benefit are reviewed. Results support strategic therapeutic testing to enhance "abscopal effect."

Adjuvant nodal field radiation in resected Stage III melanoma: A single-centre retrospective study in Christchurch, New Zealand

INTRODUCTION

Stage III melanoma is associated with poor outcomes. We studied the characteristics and outcomes of patients with resected Stage III melanoma before the routine use of adjuvant immunotherapy. Some of these patients received adjuvant nodal radiation with modern radiation techniques.

METHODS

We retrieved data of patients with resected Stage III melanoma treated in Christchurch over 10 years. Overall survival (OS), melanoma-specific survival (MSS), recurrence-free survival (RFS) and nodal recurrence-free rate (NRFR) were determined, and the association of these outcomes with tumour and treatment factors was investigated.

RESULTS

We identified 178 patients (110 male and 68 female), of whom 61 received adjuvant radiation. The median age was 66.6 years, and the median follow-up was 2.7 years. First recurrences occurred in 108 (61%) patients. There were 42 (24%) nodal field relapses and 103 (58%) distant relapses. One-half of nodal relapses in patients treated with adjuvant radiation were infield. The 5-year OS, RFS, MSS and NRFR were 46.4%, 26.8%, 53.7% and 69.6%, respectively. Adjuvant radiation was associated with improved RFS and no OS benefit. T4 disease and extranodal spread were associated with poorer OS, while extranodal spread and >3 involved nodes were associated with worse RFS.

CONCLUSION

Patients treated with adjuvant radiation remain at moderate risk of regional and high risk of distant relapse, despite the use of modern radiation techniques. Adjuvant radiation was associated with improved local control but infield recurrence rates remained a problem. The role of combined adjuvant radiation and immunotherapy in improving these outcomes requires further investigation.

Unraveling tumor microenvironment heterogeneity in malignant pleural mesothelioma identifies biologically distinct immune subtypes enabling prognosis determination

Background

Malignant pleural mesothelioma (MPM) is a rare and intractable disease exhibiting a remarkable intratumoral heterogeneity and dismal prognosis. Although immunotherapy has reshaped the therapeutic strategies for MPM, patients react with discrepant responsiveness.

Methods

Herein, we recruited 333 MPM patients from 5 various cohorts and developed an in-silico classification system using unsupervised Non-negative Matrix Factorization and Nearest Template Prediction algorithms. The genomic alterations, immune signatures, and patient outcomes were systemically analyzed across the external TCGA-MESO samples. Machine learning-based integrated methodology was applied to identify a gene classifier for clinical application.

Results

The gene expression profiling-based classification algorithm identified immune-related subtypes for MPMs. In comparison with the non-immune subtype, we validated the existence of abundant immunocytes in the immune subtype. Immune-suppressed MPMs were enriched with stroma fraction, myeloid components, and immunosuppressive tumor-associated macrophages (TAMs) as well exhibited increased TGF-β signature that informs worse clinical outcomes and reduced efficacy of anti-PD-1 treatment. The immune-activated MPMs harbored the highest lymphocyte infiltration, growing TCR and BCR diversity, and presented the pan-cancer immune phenotype of IFN-γ dominant, which confers these tumors with better drug response when undergoing immune checkpoint inhibitor (ICI) treatment. Genetically, BAP1 mutation was most commonly found in patients of immune-activated MPMs and was associated with a favorable outcome in a subtype-specific pattern. Finally, a robust 12-gene classifier was generated to classify MPMs with high accuracy, holding promise value in predicting patient survival.

Conclusions

We demonstrate that the novel classification system can be exploited to guide the identification of diverse immune subtypes, providing critical biological insights into the mechanisms driving tumor heterogeneity and responsible for cancer-related patient prognoses.

TISSUE ENGINEERED CANCER METASTASES AS CANCER VACCINE TO IMPROVE CANCER IMMUNOTHERAPY

Radiotherapy is often used to improve cancer immunotherapy outcomes. While there are both pre-clinical and clinical data supporting this approach, there are also significant challenges. One key challenge is that not all patients have tumors that can be easily treated with radiotherapy due to potential normal tissue toxicity and prior treatment. In addition, it is difficult to control the tumor microenvironment to promote the immune response after radiosurgery. To overcome these challenges, we hypothesize that we can engineer cancer metastasis and utilize irradiated engineered tumor cells as a personalized cancer vaccine to improve cancer immunotherapy. Herein, we report the development of engineered lung metastasis using decellularized rat lung tissue. Using the B16F10 melanoma tumor model, we showed that radiotherapy-treated engineered metastases are highly effective in improving cancer immunotherapy responses and more effective than in vivo metastasis. Our work has demonstrated the potential of applying tissue engineering to cancer immunotherapy. STATEMENT OF SIGNIFICANCE: Combination of radiation and immunotherapy are an effective way to treat metastasis. Despite their success, long term response still remains low. Tumor microenvironment evading the immune response, normal tissue toxicity to radiation and inaccessibility to radiosurgery are some of the limitations. To overcome these challenges, in this paper we present with data supporting the use of high dose radiation treated ex vivo engineered B16F10 metastasis model using decellularized lung scaffolds. These engineered metastases closely mimic the in vivo tumors and when given into tumor bearing mice along with check point inhibitors are highly effective in improving the cancer immunotherapy response.

Immunomodulatory effects of carbon ion radiotherapy in patients with localized prostate cancer

PURPOSE

Radiotherapy is one of the main local treatment modalities for prostate cancer, while immunosuppressive effect induced by radiotherapy is an important factor of radiation resistance and treatment failure. Carbon ion radiotherapy (CIRT) is a novel radiotherapy technique and the immunomodulatory effect of CIRT provides the possibility of overcoming radioresistance and improving efficacy. The aim of this study was to assess the immune response evoked by CIRT in localized prostate cancer patients.

METHODS

Thirty-two patients were treated by CIRT combined with or without hormone therapy and peripheral blood samples were collected before and after CIRT. Investigation of peripheral immune cell frequency, proliferation, and cytokine expression was conducted by flow cytometry, real-time quantitative PCR and ELISA.

RESULTS

There were no significant differences in the frequencies of CD3 + , CD4 + , CD8 + T cells and NK cells after CIRT. CD4/CD8 ratio increased whereas B cells decreased. All lymphocyte subsets except regulatory T cells (Tregs) displayed increased proliferation and T cells exhibited increased functionality after CIRT, characterized by modestly increased cytokine secretion of TNF. Moreover, higher frequencies of Tregs were shown. Neither monocytic myeloid-derived suppressor cells (MDSCs) nor early MDSCs changed after CIRT. TGF-β1 gene expression decreased while IL-6 showed a non-significant trend towards a decrease. Both IL-10 gene expression and plasma TGF-β1 level were unchanged.

CONCLUSION

CIRT demonstrates the potential to elicit immune activation in localized prostate cancer patients, based on sparing lymphocytes, increased lymphocyte proliferation, enhanced T-cell functionality, together with limited induction of immunosuppressive cells and reduced expression of immunosuppressive cytokines.

The Evolving Interplay of SBRT and the Immune System, along with Future Directions in the Field

Simple Summary

We provide this commentary of stereotactic body radiotherapy (SBRT), and describe our evolving understanding of this treatment approach, its effects on the immune system, and the ability to stimulate immune cells to further recognize and attack cancer. The aim of this work is to describe our current knowledge of how SBRT effects the environment within the tumor and the immune cells present, whether timing the combination of this treatment with that of immunotherapy may have an impact on the body’s own immune response, and what the latest approaches in the field are in regards to this radiation treatment modality. Among these latest and exciting developments is Personalized Ultrafractionated Stereotactic Adaptive Radiation Therapy, known as PULSAR. This latest approach is described in detail herein, and may represent a leading novel method for adapting radiation treatments to treatment-induced tumor changes over time and stimulating the body’s immune response against tumor cells.

Abstract

In this commentary, we describe the potential of highly ablative doses utilizing Stereotactic Body Radiation Therapy (SBRT) in single or few fractions to enhance immune-responsiveness, how timing of this approach in combination with immune-checkpoint inhibitors may augment treatment-effect, and whether Personalized Ultrafractionated Stereotactic Adaptive Radiation Therapy (PULSAR) is an avenue for future advancement in the continued endeavor to foster a systemic effect of therapy beyond the radiation treatment field. The ablative potential of SBRT may support an increase in tumor-antigen presentation, enhancement of immune-stimulatory components, and an improvement in tumor-microenvironment immune cell infiltration. Furthermore, the latest advancement of ablative radiation delivery is PULSAR-based therapy, whereby ablative doses are delivered in pulses of treatment that may be several weeks apart, combined with adaptive treatment to tumor changes across time. The benefits of this novel approach include the ability to optimize direct tumor control by assessment of tumor size and location via dedicated imaging acquired prior to each delivered pulse, and further potentiation of immune recognition through combination with concurrent immune-checkpoint blockade.

Preventive cancer stem cell-based vaccination modulates tumor development in syngeneic colon adenocarcinoma murine model

BACKGROUND

Cancer stem cells (CSCs), a rare sub-fraction of tumor cells, with the capability of self-renewal and strong oncogenicity are tightly responsible for chemo and radio resistance and tumor metastasis in colorectal cancer. Hence, CSCs targeting would improve the efficacy of therapeutic strategies and clinical outcomes.

METHODS

Here, using three-dimensional CSC spheroids and syngeneic mice model, we evaluated the cancer preventive impact of CSCs-based vaccination. CSCs enrichment was performed via colonosphere formation from CT-26 cell line and CT-26-derived tumor biopsy and characterized by confirming high expression of key stemness genes (OCT4, SOX2, and NANOG) and CSC-related surface biomarkers (CD166, DCLK1, and CD133) via real-time PCR and flow cytometry, respectively. Then, the stemness phenotype and self-renewal in CSC-enriched spheroids were further confirmed by showing serial sphere formation capacity, clonogenicity potential, and enhanced in vivo tumorigenic capacity compared to their parental counterparts. CSCs lysates were used as vaccines in prophylactic settings compared to the parental cell lysate and PBS groups.

RESULT

Immunization of syngeneic mice with CSCs lysates was effective in the prevention of tumor establishment and significantly decreased tumor growth rate accompanied by an improvement in survival rate in tumor-bearing mice compared to groups subjected to parental cells lysate and PBS. These results, for the first time, showed that mice immunized with cell lysate from tumor biopsy-derived spheroids are resistant to tumor induction. Immunofluorescence staining indicated that only the serum antibodies from CSC-vaccinated mice reacted with colonospheres.

CONCLUSIONS

These findings represent CSCs lysate-based vaccination as a potential approach to hampering immunotherapy failure of colorectal cancer which along with other traditional therapies may effectively apply to prevent the establishment of aggressive tumors harboring stemness features.

Stereotactic body radiotherapy extends the clinical benefit of PD-1 inhibitors in refractory recurrent/metastatic nasopharyngeal carcinoma

Purpose

Emerging evidence shows that immune checkpoint inhibitors lead to durable responses in a variety of cancers, including nasopharyngeal carcinoma (NPC), however, combination approaches (i.e., stereotactic body radiation therapy, SBRT) are required to extend this benefit beyond a subset of patients. This study retrospectively evaluated eight recurrent/metastatic NPC patients, to investigate how radiation could potentiate PD-1 checkpoint inhibition therapy.

Methods

Between September 2016 and July 2017, eight consecutive cases with histologically confirmed PDL1-positive status, for which prior standard therapy had been ineffective (five patients), were treated at our institution and Macao Clinics and two patients had disease progression within 6 months of completion of definitive chemoradiation, or one patient refused to receive chemoradiotherapy. All received PD-1 inhibitors first, seven of them accepted SBRT with an unmodified PD-1 inhibitors regimen after first evaluation as they were unresponsive to PD-1 inhibitors alone. Treatment was discontinued as long as patients were experiencing a clinical benefit in the opinion of the physicians and at least five cycles were given before stoppage.

Results

Median follow-up time was 56.7 months. The confirmed objective response rate based on RECIST-v1.1 at first evaluation was 12.5% (1/8). For the seven cases who received SBRT, six of them experience an objective response (6/7, 85.7%) after SBRT. Only one patient showed rapid progress and die within 95 days after the initiation of SBRT intervention. Three patients who did not have all lesions exposed to irradiation were available to evaluate the incidence of an abscopal effect, however, it did not occur as expected. Median PFS and OS for the seven patients were 8.0 and 30.8 months after SBRT intervention, respectively. Two-year OS as indicated was 71.0%.

Conclusions

PD-1 inhibitors combined with SBRT demonstrated promising antitumor activity in patients with PD-L1 positive RM-NPC. Patients may benefit from continue immunotherapy beyond disease progression when SBRT was introduced.

The SRPK inhibitor N-(2-(piperidin-1-yl)-5-(trifluoromethyl)phenyl) isonicotinamide (SRPIN340) increases the immune response against metastatic melanoma in mice

Cancers have a strong relationship with immune cells in their microenvironment, which significantly influences tumor proliferation and progression. Thus, pharmacological strategies that stimulate the immune system to combat tumor cells are promising for better therapeutic efficacy. Deregulated expression of the splicing regulatory serine arginine protein kinases (mostly SRPK1 and SRPK2) has been found in different cancer types, leading to the expression of isoforms related to tumor growth and metastasis. The microenvironment of melanoma exhibits a strong presence of immune cells, which significantly influences tumor progression, and around 50% of cutaneous melanoma patients benefit from targeted immunotherapy. Here, we analyzed human malignant melanoma single-cell gene expression data and observed that SRPK1/2 overexpression correlates with immune system pathway alterations. In further analysis, we observed an increased presence of immune cells in biopsies from mice bearing metastatic melanoma treated with SRPIN340, a well-known SRPK1/2 pharmacological inhibitor. Local treatments increased the expression of proinflammatory cytokines at the tumor lesions and the activity of the spleen, accompanied by reduced pulmonary metastasis foci, edema formation, and alveolar congestion. In in vitro assays, SRPIN340 also potentiated immunological susceptibility, by increasing the expression of the antigen presenting MHCI and MHCII molecules and by increasing the ability of B16F10 cells to attract splenic cells in transwell assays. Taken together, these results reveal that the antimetastatic effect of SRPIN340 can also involve an increased immune response, which suggests additional functional clues for SRPKs in tumor biology.

The Evolving Role of PD-L1 Inhibition in Non-Small Cell Lung Cancer: A Review of Durvalumab and Avelumab

Non-small cell lung cancer (NSCLC) was traditionally associated with a poor prognosis. Between 2010 and 2016, the 5-years overall survival for all stages combined was about 25 percent. However, the recent use of immunotherapy has led to significant improvements in progression free survival (PFS) and overall survival (OS). Immune check point inhibitors enable the host immune system to mount a lethal response against tumor cells. Both PD-1 (nivolumab, pembrolizumab, cemipilimab) and PD-L1 inhibitors (atezolizumab and durvalumab) have been approved by the FDA for use in NSCLC, either as individual agents or in combination with platinum-based chemotherapy, radiation therapy, or other agents. As the future of immunotherapy for lung cancer continues to evolve, with multiple agents approved or in various stages of clinical research, it is imperative that we understand the mechanism of action, clinical activity, ongoing clinical trials, indications for use and toxicity for individual agents in addition to having general, basic knowledge about this new class of cancer therapeutics. In this review, we focus on two of the newer PD-L1 inhibitors, durvalumab and avelumab.

Application of Noninvasive Imaging to Combined Immune Checkpoint Inhibitors for Breast Cancer: Facts and Future

With the application of mono-immunotherapy in cancer, particularly immune checkpoint inhibitors, improved outcomes have been achieved. However, there are several limitations to immunotherapy, such as a poor response to the drugs, immune resistance, and immune-related adverse events. In recent years, studies of preclinical animal models and clinical trials have demonstrated that immune checkpoint inhibitors for breast cancer can significantly prolong the overall survival and quality of patients' lives. Meanwhile, combined immune checkpoint inhibitor treatment has attracted researchers' attention and showed great potential in the comprehensive treatment of breast cancer patients. Additionally, noninvasive imaging enables physicians to predict response to combined immunotherapeutic drugs, achieve treatment efficacy, and lead to better clinical management. Herein, we review the background of combined immune checkpoint inhibitor therapy and summarize its targeted imaging as well as progress in noninvasive imaging aimed at evaluating therapeutic outcomes. Finally, we describe several factors that may influence the outcome of this combined immunotherapy, the future direction of medical imaging, and the potential application of artificial intelligence in breast cancer. With further development of noninvasive imaging for the guidance of combined immune checkpoint inhibitors, cures for this disease may be achieved.

Immune Checkpoint Inhibition in GBM Primed with Radiation by Engineered Extracellular Vesicles

The lack of safe and effective delivery across the blood-brain barrier and the profound immune suppressive microenvironment are two main hurdles to glioblastoma (GBM) therapies. Extracellular vesicles (EVs) have been used as therapeutic delivery vehicles to GBM but with limited efficacy. We hypothesized that EV delivery to GBM can be enhanced by (i) modifying the EV surface with a brain-tumor-targeting cyclic RGDyK peptide (RGD-EV) and (ii) using bursts of radiation for enhanced accumulation. In addition, EVs were loaded with small interfering RNA (siRNA) against programmed cell death ligand-1 (PD-L1) for immune checkpoint blockade. We show that this EV-based strategy dramatically enhanced the targeting efficiency of RGD-EV to murine GBM, while the loaded siRNA reversed radiation-stimulated PD-L1 expression on tumor cells and recruited tumor-associated myeloid cells, offering a synergistic effect. The combined therapy significantly increased CD8+ cytotoxic T cells activity, halting tumor growth and prolonging animal survival. The selected cell source for EVs isolation and the presented functionalization strategy are suitable for large-scale production. These results provide an EV-based therapeutic strategy for GBM immune checkpoint therapy which can be translated to clinical applications.

Case Report: Chemotherapy and Radiotherapy Combined With DC-CIK for Pulmonary and Mediastinal Metastases From Nasopharyngeal Carcinoma

Introduction

The optimal treatment for pulmonary and mediastinal metastasis of nasopharyngeal carcinoma (NPC) is still controversial, and the therapeutic effect is poor recently. In one case, we demonstrated a long-term survival after postoperative chemoradiotherapy combined with dendritic cell and cytokine-induced killer (DC-CIK) immunotherapy for pulmonary and mediastinal metastases from NPC.

Baseline Characteristics

A 53-year-old woman was admitted to our hospital in June 2008. Pathological biopsy revealed a poorly differentiated squamous cell carcinoma located in the nasopharynx with the invasion of internal pterygoid muscles, the sphenoid bone, and unilateral neck lymph node metastasis. No distant metastases were observed. The stage of NPC was T3N1M0 III (AJCC8). The patient received concurrent chemoradiotherapy for primary lesion and neck lymph nodes and achieved complete remission (CR) of the disease after 3 months. Follow-up at 3-month intervals was carried out. Pulmonary and mediastinal lymph node metastases were found in July 2009. The patient then underwent right upper lobectomy and mediastinal lymph node dissection and five cycles of gemcitabine and cisplatin (GP) regimen chemotherapy, following radiotherapy and DC-CIK immunotherapy.

Results

After a follow-up time of 13 years, no tumor recurrence or metastasis and severe adverse reactions were found.

Conclusion

Postoperative chemotherapy and radiotherapy in combination with DC-CIK immunotherapy may produce a synergistic therapeutic effect on patients with mediastinal lymph node metastasis from NPC.

Pharmacologic inhibition of ataxia telangiectasia and Rad3-related (ATR) in the treatment of head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) poses significant treatment challenges, with high recurrence rates for locally advanced disease despite aggressive therapy typically involving a combination of surgery, radiation therapy, and/or chemotherapy. HNSCCs commonly exhibit reduced or absent TP53 function due to genomic alterations or human papillomavirus (HPV) infection, leading to dependence on the S- and G2/M checkpoints for cell cycle regulation. Both of these checkpoints are activated by Ataxia Telangiectasia and Rad3-related (ATR), which tends to be overexpressed in HNSCC relative to adjacent normal tissues and represents a potentially promising therapeutic target, particularly in combination with other treatments. ATR is a DNA damage signaling kinase that is activated in response to replication stress and single-stranded DNA breaks, such as those induced by radiation therapy and certain chemotherapies. ATR kinase inhibitors are currently being investigated in several clinical trials as part of the management of locally advanced, recurrent, or metastatic HNSCC, along with other malignancies. In this review article, we summarize the rationale and preclinical data supporting incorporation of ATR inhibition into therapeutic regimens for HNSCC.

Outcomes of adults with lymphoma treated with nonmyeloablative TLI-ATG and radiation boost to high risk or residual disease before allogeneic hematopoietic cell transplant

We evaluated the impact on survival of antithymocyte globulin conditioning (TLI-ATG) with radiation (RT) boost to high risk or residual disease before allogeneic hematopoietic cell transplant (allo-HCT) for adults with lymphoma (excluding mycosis fungoides and low-grade NHL other than SLL/CLL). Of 251 evaluable patients, 36 received an RT boost within 3 months of allo-HCT at our institution from 2001 to 2016. At the time of TLI-ATG, patients who received boost vs no boost had a lower rate of CR (11% vs 47%, p = 0.0003), higher rates of bulky disease (22% vs 4%, p < 0.0001), extranodal disease (39% vs 5%, p < 0.0001), and positive PET (75% vs 28%, p < 0.00001). In the boost group, the median (range) largest axial lesion diameter was 5.2 cm (1.8-22.3). Median follow-up was 50.2 months (range: 1-196). There was no significant difference in OS, time to recurrence, or time to graft failure with vs without boost. A trend toward higher percent donor CD3⁺ chimerism was seen with vs without boost (p = 0.0819). The worst boost-related toxicity was grade 2 dermatitis. RT boost may help successfully mitigate the risk of high risk or clinically evident residual disease in adults with lymphoma undergoing allo-HCT.

Recent Advances in Brachytherapy Using Radioactive Nanoparticles: An Alternative to Seed-Based Brachytherapy

Interstitial brachytherapy (BT) is generally used for the treatment of well-confined solid tumors. One example of this is in the treatment of prostate tumors by permanent placement of radioactive seeds within the prostate gland, where low doses of radiation are delivered for several months. However, successful implementation of this technique is hampered due to several posttreatment adverse effects or symptoms and operational and logistical complications associated with it. Recently, with the advancements in nanotechnology, radioactive nanoparticles (radio-NPs) functionalized with tumor-specific biomolecules, injected intratumorally, have been reported as an alternative to seed-based BT. Successful treatment of solid tumors using radio-NPs has been reported in several preclinical studies, on both mice and canine models. In this article, we review the recent advancements in the synthesis and use of radio-NPs as a substitute to seed-based BT. Here, we discuss the limitations of current seed-based BT and advantages of radio-NPs for BT applications. Recent progress on the types of radio-NPs, their features, synthesis methods, and delivery techniques are discussed. The last part of the review focuses on the currently used dosimetry protocols and studies on the dosimetry of nanobrachytherapy applications using radio-NPs. The current challenges and future research directions on the role of radio-NPs in BT treatments are also discussed.

Effect of prior thoracic radiotherapy on prognosis in relapsed small cell lung cancer patients treated with anlotinib: a subgroup analysis of the ALTER 1202 trial

Background

In ALTER 1202, anlotinib prolonged the progression-free survival (PFS) and overall survival (OS) of patients with relapsed small cell lung cancer (SCLC). The aim of this study was to explore the effect of front-line thoracic radiotherapy (RT) on the benefits of anlotinib as a third-line-or-beyond treatment.

Methods

This was a subgroup analysis of a multicenter, randomized, double-blind, placebo-controlled phase 2 trial (ALTER 1202). The participants were divided into RT (previous thoracic RT) and non-RT subgroups. The outcomes included PFS, OS, objective response rate (ORR), disease control rate (DCR), and safety.

Results

In the ALTER 1202 trial, 68 participants (anlotinib, n=46; placebo, n=22) received RT and 51 participants (anlotinib, n=35; placebo, n=16) did not. PFS was longer for anlotinib versus placebo in both the RT (5.49 vs. 0.69 months; P<0.001) and non-RT (2.83 vs. 0.76 months; P<0.001) subgroups. In the RT subgroup, the OS was longer for anlotinib vs. placebo (9.49 vs. 4.90 months; P=0.039). No differences were found in the ORR, but the DCR was higher in the anlotinib arm of the RT subgroup compared with the placebo arm (73.9% vs. 9.1%, P<0.001) and the non-RT subgroup (68.6% vs. 18.8%; P=0.002).

Conclusions

In relapsed SCLC patients with previous thoracic RT, anlotinib might have DCR, PFS, and OS benefits compared with placebo. In those without previous thoracic RT patients, anlotinib might have DCR and PFS benefits compared with placebo. The safety was similar between anlotinib and placebo groups.

The Abscopal Effect: A Review of Pre-Clinical and Clinical Advances

Radiotherapy has been used for more than a hundred years to cure or locally control tumors. Regression of tumors outside of the irradiated field was occasionally observed and is known as the abscopal effect. However, the occurrence of systemic anti-tumor effects was deemed too rare and unpredictable to be a therapeutic goal. Recent studies suggest that immunotherapy and radiation in combination may enhance the abscopal response. Increasing numbers of cases are being reported since the routine implementation of immune checkpoint inhibitors, showing that combined radiotherapy with immunotherapy has a synergistic effect on both local and distant (i.e., unirradiated) tumors. In this review, we summarize pre-clinical and clinical reports, with a specific focus on the mechanisms behind the immunostimulatory effects of radiation and how this is enhanced by immunotherapy.

Targeted Alpha-Particle Radiotherapy and Immune Checkpoint Inhibitors Induces Cooperative Inhibition on Tumor Growth of Malignant Melanoma

Simple Summary

Radiation therapy and immune checkpoint inhibitors (ICIs) have been demonstrated to cooperatively activate adaptive anti-tumor immunity with curative potential in preclinical models of melanoma. Receptor-targeted radionuclide therapy can be systemically injected to selectively deliver ionizing radiation to tumor sites throughout the body, potentially rendering all tumor sites more susceptible to anti-tumor immune response. In this study, we demonstrated the feasibility of delivering alpha-particle radiation to murine melanoma tumors using a ²¹²Pb radiolabeled peptide [²¹²Pb]VMT01 that targets the melanocortin 1 receptor (MC1R). Our data showed anti-tumor cooperation between [²¹²Pb]VMT01 and ICIs in melanoma, mediated by induction of tumor-specific immunity. The immunogenicity of [²¹²Pb]VMT01 in melanoma was also evidenced by enhanced tumor infiltrating lymphocytes and tumor vaccination assays.

Abstract

Radiotherapy can facilitate the immune recognition of immunologically “cold” tumors and enhance the efficacy of anti-PD-1 and anti-CTLA-4 immune checkpoint inhibitors (ICIs) in melanoma. Systemic administration of receptor-targeted radionuclide therapy has the potential to selectively deliver radionuclides to multiple tumors throughout the body in metastatic settings. By triggering immunologic cell death and increasing the immune susceptibility of surviving tumor cells in these locations, targeted radionuclide therapies may overcome resistance to ICIs and render immunologically “cold” tumors throughout the body responsive to ICIs and immunologically “hot”. Here, we show the anti-tumor cooperation of targeted α-particle radionuclide therapy (α-TRT) and ICIs in preclinical models of melanoma. Melanocortin 1 receptor (MC1R)-targeted radiopeptide [²¹²Pb]VMT01 was employed to deliver α-radiation to melanoma tumors in mice. A single injection of 4.1 MBq [²¹²Pb]VMT01 significantly slowed the tumor growth of B16-F10 melanoma and the combination of [²¹²Pb]VMT01 and ICIs induced a cooperative anti-tumor effect leading to 43% complete tumor response with no sign of malignancy on autopsy. Animals with complete response developed anti-tumor immunity to reject further tumor inoculations. This therapeutic cooperation was completely abolished in RAG1 KO mice, which are deficient in T-cell maturation. In addition, the anti-tumor cooperation was compromised when fractionated [²¹²Pb]VMT01 was used in the combination. We also demonstrated that [²¹²Pb]VMT01 induced immunogenic cell death in tumor vaccination assays and in vitro exposure to [²¹²Pb]VMT01 sensitized immunotolerant melanoma to ICIs treatment in vivo. Enhanced tumor infiltrating CD3⁺, CD4⁺, CD8⁺ lymphocytes were observed following injection of 1.4 MBq [²¹²Pb]VMT01. Overall, we demonstrated anti-tumor cooperation between α-TRT and ICIs in melanoma that is mediated by tumor specific immunity.

Low-dose total body irradiation facilitates antitumoral Th1 immune responses

CD4⁺ T helper cells are capable of mediating long-term antitumoral immune responses. We developed a combined immunotherapy (COMBO) using tumor antigen-specific T helper 1 cells (Tag-Th1), dual PD-L1/LAG-3 immune checkpoint blockade, and a low-dose total body irradiation (TBI) of 2 Gy, that was highly efficient in controlling the tumor burden of non-immunogenic RIP1-Tag2 mice with late-stage endogenous pancreatic islet carcinomas. In this study, we aimed to explore the impact of 2 Gy TBI on the treatment efficacy and the underlying mechanisms to boost CD4⁺ T cell-based immunotherapies. Methods: Heavily progressed RIP1-Tag2 mice underwent COMBO treatment and their survival was compared to a cohort without 2 Gy TBI. Positron emission tomography/computed tomography (PET/CT) with radiolabeled anti-CD3 monoclonal antibodies and flow cytometry were applied to investigate 2 Gy TBI-induced alterations in the biodistribution of endogenous T cells of healthy C3H mice. Migration and homing properties of Cy5-labeled adoptive Tag-Th1 cells were monitored by optical imaging and flow cytometric analyses in C3H and tumor-bearing RIP1-Tag2 mice. Splenectomy or sham-surgery of late-stage RIP1-Tag2 mice was performed before onset of COMBO treatment to elucidate the impact of the spleen on the therapy response. Results: First, we determined a significant longer survival of RIP1-Tag2 mice and an increased CD4⁺ T cell tumor infiltrate when 2 Gy TBI was applied in addition to Tag-Th1 cell PD-L1/LAG-3 treatment. In non-tumor-bearing C3H mice, TBI induced a moderate host lymphodepletion and a tumor antigen-independent accumulation of Tag-Th1 cells in lymphoid and non-lymphoid organs. In RIP1-Tag2, we found increased numbers of effector memory-like Tag-Th1 and endogenous CD4⁺ T cells in the pancreatic tumor tissue after TBI, accompanied by a tumor-specific Th1-driven immune response. Furthermore, the spleen negatively regulated T cell effector function by upregulation PD-1/LAG-3/TIM-3 immune checkpoints, providing a further rationale for this combined treatment approach. Conclusion: Low-dose TBI represents a powerful tool to foster CD4⁺ T cell-based cancer immunotherapies by favoring Th1-driven antitumoral immunity. As TBI is a clinically approved and well-established technique it might be an ideal addition for adoptive cell therapy with CD4⁺ T cells in the clinical setting.

Multidiscipline Immunotherapy-Based Rational Combinations for Robust and Durable Efficacy in Brain Metastases from Renal Cell Carcinoma

Advanced imaging techniques for diagnosis have increased awareness on the benefits of brain screening, facilitated effective control of extracranial disease, and prolonged life expectancy of metastatic renal cell carcinoma (mRCC) patients. Brain metastasis (BM) in patients with mRCC (RCC-BM) is associated with grave prognoses, a high degree of morbidity, dedicated assessment, and unresponsiveness to conventional systemic therapeutics. The therapeutic landscape of RCC-BM is rapidly changing; however, survival outcomes remain poor despite standard surgery and radiation, highlighting the unmet medical needs and the requisite for advancement in systemic therapies. Immune checkpoint inhibitors (ICIs) are one of the most promising strategies to treat RCC-BM. Understanding the role of brain-specific tumor immune microenvironment (TIME) is important for developing rationale-driven ICI-based combination strategies that circumvent tumor intrinsic and extrinsic factors and complex positive feedback loops associated with resistance to ICIs in RCC-BM via combination with ICIs involving other immunological pathways, anti-antiangiogenic multiple tyrosine kinase inhibitors, and radiotherapy; therefore, novel combination approaches are being developed for synergistic potential against RCC-BM; however, further prospective investigations with longer follow-up periods are required to improve the efficacy and safety of combination treatments and to elucidate dynamic predictive biomarkers depending on the interactions in the brain TIME.

Recurrent/Metastatic Squamous Cell Carcinoma of the Head and Neck: A Big and Intriguing Challenge Which May Be Resolved by Integrated Treatments Combining Locoregional and Systemic Therapies

Squamous cell carcinoma of the head and neck (SCCHN) is a complex group of malignancies, posing several challenges to treating physicians. Most patients are diagnosed with a locally advanced disease and treated with strategies integrating surgery, chemotherapy, and radiotherapy. About 50% of these patients will experience a recurrence of disease. Recurrent/metastatic SCCHN have poor prognosis with a median survival of about 12 months despite treatments. In the last years, the strategy to manage recurrent/metastatic SCCHN has profoundly evolved. Salvage treatments (surgery or re-irradiation) are commonly employed in patients suffering from locoregional recurrences and their role has gained more and more importance in the last years. Re-irradiation, using some particularly fractionating schedules, has the dual task of reducing the tumor mass and eliciting an immune response against cancer (abscopal effect). In this review, we will analyze the main systemic and/or locoregional strategies aimed at facing the recurrent/metastatic disease, underlining the enormous importance of the multidisciplinary approach in these types of patients.

Immunotherapy Combined With Radiation Therapy for Genitourinary Malignancies

Immunotherapy drugs have recently been approved by the Food and Drug Administration for the treatment of several genitourinary malignancies, including bladder cancer, renal cancer, and prostate cancer. Preclinical data and early clinical trial results suggest that immune checkpoint inhibitors can act synergistically with radiation therapy to enhance tumor cell killing at local irradiated sites and in some cases at distant sites through an abscopal effect. Because radiation therapy is commonly used in the treatment of genitourinary malignancies, there is great interest in testing the combination of immunotherapy with radiation therapy in these cancers to further improve treatment efficacy. In this review, we discuss the current evidence and biological rationale for combining immunotherapy with radiation therapy, as well as emerging data from ongoing and planned clinical trials testing the efficacy and tolerability of this combination in the treatment of genitourinary malignancies. We also outline outstanding questions regarding sequencing, dose fractionation, and biomarkers that remain to be addressed for the optimal delivery of this promising treatment approach.

Combined Radionuclide Therapy and Immunotherapy for Treatment of Triple Negative Breast Cancer

Triple negative breast cancer (TNBC) is an aggressive subtype of the disease with poor clinical outcomes and limited therapeutic options. Immune checkpoint blockade (CP) has surged to the forefront of cancer therapies with widespread clinical success in a variety of cancer types. However, the percentage of TNBC patients that benefit from CP as a monotherapy is low, and clinical trials have shown the need for combined therapeutic modalities. Specifically, there has been interest in combining CP therapy with radiation therapy where clinical studies primarily with external beam have suggested their therapeutic synergy, contributing to the development of anti-tumor immunity. Here, we have developed a therapeutic platform combining radionuclide therapy (RT) and immunotherapy utilizing a radiolabeled biomolecule and CP in an E0771 murine TNBC tumor model. Survival studies show that while neither monotherapy is able to improve therapeutic outcomes, the combination of RT + CP extended overall survival. Histologic analysis showed that RT + CP increased necrotic tissue within the tumor and decreased levels of F4/80+ macrophages. Flow cytometry analysis of the peripheral blood also showed that RT + CP suppressed macrophages and myeloid-derived suppressive cells, both of which actively contribute to immune escape and tumor relapse.