Randomized Phase II Trial of Nivolumab With Stereotactic Body Radiotherapy Versus Nivolumab Alone in Metastatic Head and Neck Squamous Cell Carcinoma

Top Ten Lessons Learned from Trials in Oligometastatic Cancers

Recent evidence supports the role of aggressive local treatment in the oligometastatic setting. In this review, we discuss the top 10 lessons we have learned from trials in oligometastatic cancers. Major lessons learned pertain to definitions of oligometastatic disease, outcomes, toxicity, costs, and the combination of ablative therapies with systemic therapy, including immunotherapy. Barriers to accrual for trials and upcoming phase III trials are also reviewed. These lessons may help to inform clinical practice and may be the basis for future research in the oligometastatic space.

Abscopal effect triggered by radiation sequential mono-immunotherapy resulted in a complete remission of PMMR sigmoid colon cancer

Background

Radiation therapy combined with immune checkpoint inhibitors (ICIs) has recently turned into an appealing and promising approach to enhance the anti-tumor immunity and efficacy of immunological drugs in many tumors. Abscopal effect induced by radiation is a phenomenon that often leads to an efficient immunity response. In this study, we investigated whether the combination of the immunogenic effects derived from radiotherapy sequential ICIs-based therapy could increase the incidence of abscopal effects, and improve the survival rates.

Case presentation

We described a clinical case regarding a 35-year-old male patient who was admitted to our hospital with a diagnosis of adenocarcinoma of the sigmoid colon and synchronous multiple liver metastases following a surgical resection. The molecular pathological examination showed immune-desert phenotype and proficient mismatch repair (pMMR). The patient was treated with adjuvant chemotherapy after surgery, however, after 7 months, multiple metastasis in the pelvic lymph nodes were diagnosed. Unfortunately, the tumor progressed despite multiple cycles of chemotherapy combined with cetuximab or bevacizumab. Within the follow-up treatment, the patient was administered with only 50Gy/25F of radiation dose to treat the anastomotic lesions. Subsequently, mono-sindilizumab was used as systemic therapy, leading to a rapid reduction of all pelvic lesions and complete clinical remission. So far, the patient survived for more than 20 months under continuous mono-sindilizumab treatment and is still in complete remission.

Conclusion

A localized radiotherapy combined with a sindilizumab-based systemic therapy may overcome the immune resistance of pMMR metastatic colorectal cancer (mCRC), thus obtaining greater efficacy of the therapy. Its mechanism may be related to the abscopal effect obtained by the synergistic use of radiation and sindilizumab, which should be further investigated in the future.

A "scoping" review of prostate brachytherapy and immune responses

PURPOSE

Whether prostate brachytherapy (BT) results in opportunistic biological changes that can improve clinical outcomes is not well studied. We sought to investigate the impact of prostate BT on the immune system.

MATERIALS AND METHODS

A scoping review was performed using PubMed/Scopus for papers published between 2011-2021. Search terms were "brachytherapy" AND "immune" AND "prostate". A total of 81 records were identified and 6 were selected for further review.

RESULTS

2 low-dose-rate BT papers (n=68) evaluated changes in the peripheral blood following I-125 monotherapy. Both showed significant increases in peripheral CD3+ and CD4+ T cells post-BT. One also demonstrated significant increases in Treg subsets up to 150 days post-BT. 4 high-dose-rate (HDR) studies (n=37) were identified, and all were done in combination with EBRT. The largest study (n=24) showed a single 10 Gy fraction of HDR converted 80% of "cold" tumors into an "intermediate" or "hot" state, based on a tumor inflammation signature when comparing a pre-BT biopsy to one prior to a second HDR fraction.

CONCLUSION

Prostate BT can invoke an immune activating phenotype; however, changes in immunosuppressive cells are also seen. Additional data is needed to understand how to promote synergy between BT and the immune system.

Abscopal Effect after Stereotactic Body Radiotherapy with Nivolumab for Lung Metastasis of Head and Neck Cancer: A Case Report

Introduction

The abscopal effect (AE) is a phenomenon, in which radiotherapy exerts an antitumour effect on distant lesions outside the primary irradiated area. Although immune checkpoint inhibitors have been widely studied for their potential to enhance the AE and improve patient outcomes, findings in cases of head and neck cancers remain limited.

Case Presentation

We report the case of a 72-year-old man who experienced lung oligoprogression during nivolumab treatment for metastatic hypopharyngeal cancer. Stereotactic body radiotherapy (SBRT) was administered to one of the lung lesions, after which both irradiated and nonirradiated lesions regressed. Upon an 18-month follow-up period after SBRT, the patient showed no disease progression or toxicity, and continued receiving nivolumab therapy.

Conclusion

The intent behind presenting this case report was to contribute to the accumulation of evidence regarding the AE in cases of head and neck cancer.

Synergizing radiotherapy and immunotherapy: Current challenges and strategies for optimization

Numerous clinical studies are investigating the integration of radiotherapy and immune checkpoint inhibitors (ICI) in the management of advanced or metastatic solid cancers based on preclinical evidence demonstrating a synergistic interaction between these treatments. However, it remains unclear how to optimally integrate these therapeutic modalities in the treatment of cancer patients. Beyond disease-specific factors there exists numerous unanswered questions regarding optimal sequencing of radiation and ICI, as well as, radiation dosing and target selection. Here, we examine the available clinical evidence for combination radiation and ICI approaches and propose strategies to expand investigations of the potential synergy in cancer patients.

Oligometastases: Emerging Evidence

The hypothesis that ablative therapies (such as surgery or radiation) can be used to cure patients with a limited number of metastases was influential in changing practice. Early assertions of efficacy were based on observational studies, often without control groups, showing better-than-expected outcomes. However, in the past decade, new evidence from randomized trials has emerged, which in some cases have affirmed old hypotheses, but in other cases have raised new questions. In this review, we discuss the challenges in defining oligometastatic disease, summarize the randomized evidence evaluating metastasis-directed therapy in patients with oligometastatic disease, provide context for the difficulty in generating randomized evidence, and examine ongoing phase III studies.

Radiation therapy prior to CAR T-cell therapy in lymphoma: impact on patient outcomes

INTRODUCTION

Anti-CD19 chimeric antigen receptor (CAR) T-cell therapy has revolutionized the treatment paradigm for patients with refractory or recurrent (R/R) diffuse large B-cell lymphomas (DLBCL). Nonetheless, most patients ultimately progress. The use of bridging or salvage radiotherapy (RT) in combination with CAR T-cell therapy has been proposed as potential strategies to improve patient outcomes, but consensus is currently lacking as to which, if either, approach is effective.

AREAS COVERED

We reviewed the immunologic and molecular mechanisms of resistance and the current retrospective data on patterns-of-failure, clinical risk factors, and treatment outcomes in patients undergoing CAR T-cell therapy, with and without bridging or salvage RT.

EXPERT OPINION

We believe that current basic and clinical evidence supports the use of comprehensive, ablative bridging irradiation (CABI), as opposed to low-dose bridging or salvage radiotherapy, as a promising strategy to improve CAR T-cell therapy outcomes in patients with R/R DLBCL. This potential benefit is likely greatest in patients with high tumor burden and/or localized disease, who are both at elevated risk of local recurrence and can often be safely and comprehensively treated with ablative radiation doses (EQD2 > 39 Gy). Hypothesis-driven clinical trials are needed prospectively assess the impact of radiation on outcomes in patients undergoing CAR T-cell therapy.

Radiotherapy induced immunogenic cell death by remodeling tumor immune microenvironment

Emerging evidence indicates that the induction of radiotherapy(RT) on the immunogenic cell death (ICD) is not only dependent on its direct cytotoxic effect, changes in the tumor immune microenvironment also play an important role in it. Tumor immune microenvironment (TIME) refers to the immune microenvironment that tumor cells exist, including tumor cells, inflammatory cells, immune cells, various signaling molecules and extracellular matrix. TIME has a barrier effect on the anti-tumor function of immune cells, which can inhibit all stages of anti-tumor immune response. The remodeling of TIME caused by RT may affect the degree of immunogenicity, and make it change from immunosuppressive phenotype to immunostimulatory phenotype. It is of great significance to reveal the causes of immune escape of tumor cells, especially for the treatment of drug-resistant tumor. In this review, we focus on the effect of RT on the TIME, the mechanism of RT in reversing the TIME to suppress intrinsic immunity, and the sensitization effect of the remodeling of TIME caused by RT on the effectiveness of immunotherapy.

Nonsurgical Treatment Strategies for Elderly Head and Neck Cancer Patients: An Emerging Subject Worldwide

Consistent with the increasing rate of head and neck cancers among elderly adults, there has been an increase in the rate of those receiving nonsurgical treatments to maintain their function and quality of life. However, various problems, such as poor tolerance to chemoradiotherapy-related toxicity, are of greater concern in elderly adults than in younger individuals. In this review, we describe adverse events that should be particularly noted in elderly patients and provide an overview of countermeasures in nonsurgical treatments. We mainly focus on cisplatin-based chemoradiotherapy-the primary treatment for head and neck squamous cell carcinoma (HNSCC). Furthermore, we review the molecular targeted drugs and immune checkpoint inhibitors for elderly patients with HNSCC. Although the number of older patients is increasing worldwide, clinical trials aimed at determining the standard of care typically enroll younger or well-conditioned elderly patients. There is still very little evidence for treating elderly HNSCC older patients, and the question of optimal treatment needs to be explored.

Elective nodal irradiation mitigates local and systemic immunity generated by combination radiation and immunotherapy in head and neck tumors

In the setting of conventional radiation therapy, even when combined with immunotherapy, head and neck cancer often recurs locally and regionally. Elective nodal irradiation (ENI) is commonly employed to decrease regional recurrence. Given our developing understanding that immune cells are radio-sensitive, and that T cell priming occurs in the draining lymph nodes (DLNs), we hypothesize that radiation therapy directed at the primary tumor only will increase the effectiveness of immunotherapies. We find that ENI increases local, distant, and metastatic tumor growth. Multi-compartmental analysis of the primary/distant tumor, the DLNs, and the blood shows that ENI decreases the immune response systemically. Additionally, we find that ENI decreases antigen-specific T cells and epitope spreading. Treating the primary tumor with radiation and immunotherapy, however, fails to reduce regional recurrence, but this is reversed by either concurrent sentinel lymph node resection or irradiation. Our data support using lymphatic sparing radiation therapy for head and neck cancer.

A phase I/Ib trial and biological correlate analysis of neoadjuvant SBRT with single-dose durvalumab in HPV-unrelated locally advanced HNSCC

Five-year survival for human papilloma virus-unrelated head and neck squamous cell carcinomas remain below 50%. We assessed the safety of administering combination hypofractionated stereotactic body radiation therapy with single-dose durvalumab (anti-PD-L1) neoadjuvantly (n = 21) ( NCT03635164 ). The primary endpoint of the study was safety, which was met. Secondary endpoints included radiographic, pathologic and objective response; locoregional control; progression-free survival; and overall survival. Among evaluable patients at an early median follow-up of 16 months (448 d or 64 weeks), overall survival was 80.1% with 95% confidence interval (95% CI) (62.0%, 100.0%), locoregional control and progression-free survival were 75.8% with 95% CI (57.5%, 99.8%), and major pathological response or complete response was 75% with 95% exact CI (51.6%, 100.0%). For patients treated with 24 Gy, 89% with 95% CI (57.1%, 100.0%) had MPR or CR. Using high-dimensional multi-omics and spatial data as well as biological correlatives, we show that responders had: (1) an increase in effector T cells; (2) a decrease in immunosuppressive cells; and (3) an increase in antigen presentation post-treatment.

Upregulated YTHDF1 associates with tumor immune microenvironment in head and neck squamous cell carcinomas

BACKGROUND

The nature of the tumor immune microenvironment (TME) is essential for the head and neck squamous cell carcinomas (HNSCC) initiation, prognosis, and response to immunotherapy. However, its gene regulatory network remains to be elucidated.

METHODS

To identify N6-methyladenosine (m6A) regulators that are involved in regulating the HNSCC TME, a computational screen was applied to The Cancer Genome Atlas (TCGA) HNSCC patient samples. The effects of mutation, copy number variation (CNV), and transcriptional regulation on YTHDF1 expression were analyzed. We analyzed the TME infiltration, cancer-immunity cycle activities, and YTHDF1-related Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways.

RESULTS

Among the 24 m6A regulators, 3 factors (YTHDF1, ELAVL1, and METTL3) were highly correlated with TME infiltration. As the top candidate, YTHDF1 was up-regulated and amplified in HNSCC. YTHDF1 promoter gains active histone marks and high chromatin accessibility, which might be transcriptionally activated by SOX2 and TP63. Moreover, YTHDF1 expression significantly associates with tumor malignant phenotype in HNSCC, which has a positive correlation with CD4+ T cells and a negative correlation with CD8+ T cells infiltration. Specifically, YTHDF1 expression is negatively associated with the cancer-immunity cycle and immune checkpoint inhibitors. In terms of the underlying biological mechanisms, YTHDF1 may interact with YTHDF2/3 to regulate several vital immune-related pathways.

CONCLUSIONS

We identify YTHDF1 associated with TME and elucidate an underlying mechanism of immune escape in HNSCC, which might be used as a predictive marker in guiding immunotherapy.

Updates in combined approaches of radiotherapy and immune checkpoint inhibitors for the treatment of breast cancer

Breast cancer is the most prevalent non-skin cancer diagnosed in females and developing novel therapeutic strategies to improve patient outcomes is crucial. The immune system plays an integral role in the body’s response to breast cancer and modulating this immune response through immunotherapy is a promising therapeutic option. Although immune checkpoint inhibitors were recently approved for the treatment of breast cancer patients, not all patients respond to immune checkpoint inhibitors as a monotherapy, highlighting the need to better understand the biology underlying patient response. Additionally, as radiotherapy is a critical component of breast cancer treatment, understanding the interplay of radiation and immune checkpoint inhibitors will be vital as recent studies suggest that combined therapies may induce synergistic effects in preclinical models of breast cancer. This review will discuss the mechanisms supporting combined approaches with radiotherapy and immune checkpoint inhibitors for the treatment of breast cancer. Moreover, this review will analyze the current clinical trials examining combined approaches of radiotherapy, immunotherapy, chemotherapy, and targeted therapy. Finally, this review will evaluate data regarding treatment tolerance and potential biomarkers for these emerging therapies aimed at improving breast cancer outcomes.

Immune-related arthritis following pelvic radiation therapy in a patient with lung cancer receiving long-term immune checkpoint blocker treatment: Case report

Radiotherapy can trigger immune-related out-of-field "abscopal" response. We report a patient with advanced NSCLC (non-small cell lung cancer) receiving long-term anti-PD1 (programmed cell death protein 1) who have developed out-of-field immune-related arthritis following pelvic irradiation.

Immunotherapy and Radiotherapy as an Antitumoral Long-Range Weapon-A Partnership with Unsolved Challenges: Dose, Fractionation, Volumes, Therapeutic Sequence

Immunotherapy, the modern oncological treatment with immune checkpoint inhibitors (ICIs), has been part of the clinical practice for malignant melanoma for more than a decade. Anti-cytotoxic T-lymphocyte antigen 4 (CTLA4), anti-programmed cell death Protein 1 (PD-1), or anti programmed death-ligand 1 (PD-L1) agents are currently part of the therapeutic arsenal of metastatic or relapsed disease in numerous cancers; more recently, they have also been evaluated and validated as consolidation therapy in the advanced local stage. The combination with radiotherapy, a treatment historically considered loco-regional, changes the paradigm, offering-via synergistic effects-the potential to increase immune-mediated tumor destruction. However, the fragile balance between the tumoricidal effects through immune mechanisms and the immunosuppression induced by radiotherapy means that, in the absence of ICI, the immune-mediated potentiation effect of radiotherapy at a distance from the site of administration is rare. Through analysis of the preclinical and clinical data, especially the evidence from the PACIFIC clinical trial, we can consider that hypofractionated irradiation and reduction of the irradiated volume, in order to protect the immune-infiltrated tumor microenvironment, performed concurrently with the immunotherapy or a maximum of 2 weeks before the start of ICI treatment, could bring maximum benefits. In addition, avoiding radiation-induced lymphopenia (RILD) by protecting some anatomical lymphoid structures or large blood vessels, as well as the use of irradiation of partial tumor volumes, even in plurimetastatic disease, for the conversion of a "cold" immunological tumor into a "hot" immunological tumor are modern concepts of radiotherapy in the era of immunotherapy. Low-dose radiotherapy could also be proposed in plurimetastatic cases, the effect being different (modeling of the TME) from that of high doses per fraction irradiation (cell death with release of antigens that facilitates immune-mediated cell death).

Local TLR4 stimulation augments in situ vaccination induced via local radiation and anti-CTLA-4 checkpoint blockade through induction of CD8 T-cell independent Th1 polarization

BACKGROUND

Radiation therapy (RT) has been demonstrated to generate an in situ vaccination (ISV) effect in murine models and in patients with cancer; however, this has not routinely translated into enhanced clinical response to immune checkpoint inhibition (ICI). We investigated whether the commonly used vaccine adjuvant, monophosphoryl lipid A (MPL) could augment the ISV regimen consisting of combination RT and ICI.

MATERIALS/METHODS

We used syngeneic murine models of melanoma (B78) and prostate cancer (Myc-CaP). Tumor-bearing mice received either RT (12 Gy, day 1), RT+anti-CTLA-4 (C4, day 3, 6, 9), MPL (20 µg IT injection days 5, 7, 9), RT+C4+MPL, or PBS control. To evaluate the effect of MPL on the irradiated tumor microenvironment, primary tumor with tumor draining lymph nodes were harvested for immune cell infiltration analysis and cytokine profiling, and serum was collected for analysis of antitumor antibody populations.

RESULTS

Combination RT+C4+MPL significantly reduced tumor growth, increased survival and complete response rate compared with RT+C4 in both B78 and Myc-CaP models. MPL favorably reprogrammed the irradiated tumor-immune microenvironment toward M1 macrophage and Th1 TBET+CD4+ T cell polarization. Furthermore, MPL significantly increased intratumoral expression of several Th1-associated and M1-associated proinflammatory cytokines. In co-culture models, MPL-stimulated macrophages directly activated CD8 T cells and polarized CD4 cells toward Th1 phenotype. MPL treatment significantly increased production of Th1-associated, IgG2c antitumor antibodies, which were required for and predictive of antitumor response to RT+C4+MPL, and enabled macrophage-mediated antibody-dependent direct tumor cell killing by MPL-stimulated macrophages. Macrophage-mediated tumor cell killing was dependent on FcγR expression. In metastatic models, RT and MPL generated a systemic antitumor immune response that augmented response to ICIs. This was dependent on macrophages and CD4+ but not CD8+T cells.

CONCLUSIONS

We report the potential for MPL to augment the ISV effect of combination RT+C4 through FcγR, macrophage, and TBET+CD4+ Th1 cell dependent mechanisms. To our knowledge, this is the first report describing generation of a CD8+ T cell-independent, Th1 polarized, systemic antitumor immune response with subsequent generation of immunologic memory. These findings support the potential for vaccine adjuvants to enhance the efficacy of in situ tumor vaccine approaches.

Enhancing therapeutic anti-cancer responses by combining immune checkpoint and tyrosine kinase inhibition

Over the past decade, immune checkpoint inhibitor (ICI) therapy has been established as the standard of care for many types of cancer, but the strategies employed have continued to evolve. Recently, much clinical focus has been on combining targeted therapies with ICI for the purpose of manipulating the immune setpoint. The latter concept describes the equilibrium between factors that promote and those that suppress anti-cancer immunity. Besides tumor mutational load and other cancer cell-intrinsic determinants, the immune setpoint is also governed by the cells of the tumor microenvironment and how they are coerced by cancer cells to support the survival and growth of the tumor. These regulatory mechanisms provide therapeutic opportunities to intervene and reduce immune suppression via application of small molecule inhibitors and antibody-based therapies against (receptor) tyrosine kinases and thereby improve the response to ICIs. This article reviews how tyrosine kinase signaling in the tumor microenvironment can promote immune suppression and highlights how therapeutic strategies directed against specific tyrosine kinases can be used to lower the immune setpoint and elicit more effective anti-tumor immunity.

Combined nivolumab and ipilimumab with or without stereotactic body radiation therapy for advanced Merkel cell carcinoma: a randomised, open label, phase 2 trial

BACKGROUND

Merkel cell carcinoma is among the most aggressive and lethal of primary skin cancers, with a high rate of distant metastasis. Anti-programmed death receptor 1 (anti-PD-1) and programmed death ligand 1 (PD-L1) monotherapy is currently standard of care for unresectable, recurrent, or metastatic Merkel cell carcinoma. We assessed treatment with combined nivolumab plus ipilimumab, with or without stereotactic body radiotherapy (SBRT) in patients with advanced Merkel cell carcinoma as a first-line therapy or following previous treatment with anti-PD-1 and PD-L1 monotherapy.

METHODS

In this randomised, open label, phase 2 trial, we randomly assigned adults from two cancer sites in the USA (one in Florida and one in Ohio) to group A (combined nivolumab and ipilimumab) or group B (combined nivolumab and ipilimumab plus SBRT) in a 1:1 ratio. Eligible patients were aged at least 18 years with histologically proven advanced stage (unresectable, recurrent, or stage IV) Merkel cell carcinoma, a minimum of two tumour lesions measureable by CT, MRI or clinical exam, and tumour tissue available for exploratory biomarker analysis. Patients were stratified by previous immune-checkpoint inhibitor (ICI) status to receive nivolumab 240 mg intravenously every 2 weeks plus ipilimumab 1 mg/kg intravenously every 6 weeks (group A) or the same schedule of combined nivolumab and ipilimumab with the addition of SBRT to at least one tumour site (24 Gy in three fractions at week 2; group B). Patients had to have at least two measurable sites of disease so one non-irradiated site could be followed for response. The primary endpoint was objective response rate (ORR) in all randomly assigned patients who received at least one dose of combined nivolumab and ipilimumab. ORR was defined as the proportion of patients with a complete response or partial response per immune-related Response Evaluation Criteria in Solid Tumours. Response was assessed every 12 weeks. Safety was assessed in all patients. This trial is registered with ClinicalTrials.gov, NCT03071406.

FINDINGS

50 patients (25 in both group A and group B) were enrolled between March 14, 2017, and Dec 21, 2021, including 24 ICI-naive patients (13 [52%] of 25 group A patients and 11 [44%] of 25 group B patients]) and 26 patients with previous ICI (12 [48%] of 25 group A patients and 14 [56%] of 25 group B patients]). One patient in group B did not receive SBRT due to concerns about excess toxicity. Median follow-up was 14·6 months (IQR 9·1-26·5). Two patients in group B were excluded from the analysis of the primary endpoint because the target lesions were irradiated and so the patients were deemed non-evaluable. Of the ICI-naive patients, 22 (100%) of 22 (95% CI 82-100) had an objective response, including nine (41% [95% CI 21-63]) with complete response. Of the patients who had previously had ICI exposure, eight (31%) of 26 patients (95% CI 15-52) had an objective response and four (15% [5-36]) had a complete response. No significant differences in ORR were observed between groups A (18 [72%] of 25 patients) and B (12 [52%] of 23 patients; p=0·26). Grade 3 or 4 treatment-related adverse events were observed in 10 (40%) of 25 patients in group A and 8 (32%) of 25 patients in group B.

INTERPRETATION

First-line combined nivolumab and ipilimumab in patients with advanced Merkel cell carcinoma showed a high ORR with durable responses and an expected safety profile. Combined nivolumab and ipilimumab also showed clinical benefit in patients with previous anti-PD-1 and PD-L1 treatment. Addition of SBRT did not improve efficacy of combined nivolumab and ipilimumab. The combination of nivolumab and ipilimumab represents a new first-line and salvage therapeutic option for advanced Merkel cell carcinoma.

FUNDING

Bristol Myers Squibb Rare Population Malignancy Program.

Immunotherapy Alone or in Combination with Stereotactic Body Radiotherapy in Advanced Lung Cancer: A Pooled Analysis of Randomized Clinical Trials

Background

Immunotherapy has revolutionized the treatment of advanced lung cancer. Nevertheless, it remains unclear whether adding stereotactic body radiotherapy (SBRT) to immunotherapy (IT) further improves responses and survival outcomes. Therefore, in this pooled analysis, we comprehensively compared IT plus SBRT with IT alone in patients with advanced lung cancer.

Methods

Online databases, including PubMed, Web of Science, Embase, and Cochrane CENTRAL, were systematically searched on April 24, 2022. Eligible studies were randomized clinical trials comparing IT plus SBRT to IT. The primary outcomes were the objective response rate (ORR) and disease control rate (DCR). Progression-free survival (PFS) and overall survival (OS) were explored as secondary outcomes.

Results

Overall, three phase 2 randomized clinical trials with a total of 146 previously treated lung cancer patients were enrolled. The median PFS and OS were 3.8 months and 9.5 months for IT plus SBRT versus 2.4 months and 6.1 months for IT. Comparing IT plus SBRT with IT alone, pooled risk ratios for ORR and DCR were 1.95 (95% confidence interval 1.07–3.53, p = 0.03) and 1.28 (0.94–1.73, p = 0.12). While pooled hazard ratios were 0.77 (0.25–2.42, p = 0.66) for PFS and 0.71 (0.16–3.21, p = 0.65) for OS, respectively. No publication bias was found across the trials.

Conclusion

Compared to IT alone, the addition of SBRT improved the best response but failed to prolong the survival outcomes in treating advanced lung cancer patients. Future studies are necessary to explore new modalities of the combination of IT and SBRT.

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.

Mechanisms of tumor resistance to immune checkpoint blockade and combination strategies to overcome resistance

Immune checkpoint blockade (ICB) has rapidly transformed the treatment paradigm for various cancer types. Multiple single or combinations of ICB treatments have been approved by the US Food and Drug Administration, providing more options for patients with advanced cancer. However, most patients could not benefit from these immunotherapies due to primary and acquired drug resistance. Thus, a better understanding of the mechanisms of ICB resistance is urgently needed to improve clinical outcomes. Here, we focused on the changes in the biological functions of CD8⁺ T cells to elucidate the underlying resistance mechanisms of ICB therapies and summarized the advanced coping strategies to increase ICB efficacy. Combinational ICB approaches and individualized immunotherapies require further in-depth investigation to facilitate longer-lasting efficacy and a more excellent safety of ICB in a broader range of patients.

ICOS is upregulated on T cells following radiation and agonism combined with radiation results in enhanced tumor control

Multiple preclinical studies have shown improved outcomes when radiation therapy is combined with immune modulating antibodies. However, to date, many of these promising results have failed to translate to successful clinical studies. This led us to explore additional checkpoint and co-stimulatory pathways that may be regulated by radiation therapy. Here, we demonstrate that radiation increases the expression of inducible T cell co-stimulator (ICOS) on both CD4 and CD8 T cells in the blood following treatment. Moreover, when we combined a novel ICOS agonist antibody with radiation we observed durable cures across multiple tumor models and mouse strains. Depletion studies revealed that CD8 T cells were ultimately required for treatment efficacy, but CD4 T cells and NK cells also partially contributed to tumor control. Phenotypic analysis showed that the combination therapy diminished the increased infiltration of regulatory T cells into the tumor that typically occurs following radiation alone. Finally, we demonstrate in a poorly immunogenic pancreatic tumor model which is resistant to combined radiation and anti-PD1 checkpoint blockade that the addition of this novel ICOS agonist antibody to the treatment regimen results in tumor control. These findings identify ICOS as part of a T cell pathway that is modulated by radiation and targeting this pathway with a novel ICOS antibody results in durable tumor control in preclinical models.

Immunotherapy in Head and Neck Cancer When, How, and Why?

Head and neck cancer (HNC) is one of the most common cancers worldwide. Alcohol and tobacco consumption, besides viral infections, are the main risk factors associated with this cancer. When diagnosed in advanced stages, HNC patients present a higher probability of recurrence or metastasising. The complexity of therapeutic options and post-treatment surveillance is associated with poor prognosis and reduced overall survival (OS). This review aims to explore immunotherapy (immune checkpoint inhibitors (ICI), therapeutic vaccines, and oncolytic viruses) in HNC patients’ treatment, and to explore when, how, and why patients can benefit from it. The monotherapy with ICI or in combination with chemotherapy (QT) shows the most promising results. Compared to standard therapy, ICI are able to increase OS and patients’ quality of life. QT in combination with ICI demonstrates significant response rates and considerable long-term clinical benefits. However, the toxicity associated with this approach is still a hurdle to overcome. In parallel, the therapeutic vaccines directed to the Human Papilloma Virus are also efficient in increasing the antitumour response, inducing cellular and humoral immunity. Although these results demonstrate clinical benefits compared to standard therapy, it is also important to unravel the resistance mechanisms in order to predict the clinical benefit of immunotherapy.

Efficacy and safety of transarterial chemoembolization with CalliSpheres® Microspheres in head and neck cancer

Objective

Transarterial chemoembolization with CalliSpheres® Microspheres (CSM-TACE) presents favorable efficacy and tolerable safety in several cancers, while its application in head and neck cancer (HNC) is unclear. Thus, the current pilot study aims to evaluate the efficacy and safety of CSM-TACE in treating HNC.

Methods

A total of 15 HNC patients receiving CSM-TACE at the Second Affiliated Hospital of Dalian Medical University from March 2017 to December 2021 were enrolled in this study. Moreover, treatment information, treatment response, progression-free survival (PFS), overall survival (OS), changes in liver and renal function indices, and adverse events were recorded.

Results

There were nine patients receiving CSM-TACE as first-line treatment and six patients receiving CSM-TACE as second- or above-line treatment; meanwhile, there were seven, seven, and one patient undergoing one time, two times, and three times of CSM-TACE, respectively. Furthermore, the objective response rate (ORR) and the disease control rate (DCR) were 60.0% and 100%, respectively, at the first month; meanwhile, the ORR and the DCR were 53.3% and 73.3%, respectively, at the second month. Moreover, the 1-year PFS rate was 34.1%, and the 1-year OS rate was 38.9%. Additionally, no change in liver function indices (namely, total protein, albumin, total bilirubin, alanine aminotransferase, and aspartate aminotransferase) or in renal function indices (namely, creatinine and blood urea nitrogen) was found before and 1 month after treatment (all P > 0.05). Meanwhile, no severe adverse events were found during and after CSM-TACE.

Conclusion

CSM-TACE illustrates favorable treatment response and survival benefits as well as a tolerable safety profile in HNC patients.

A cuproptosis and copper metabolism–related gene prognostic index for head and neck squamous cell carcinoma

Background

The purpose of this study was to identify the prognostic value of cuproptosis and copper metabolism–related genes, to clarify their molecular and immunological characteristics, and to elucidate their benefits in head and neck squamous cell carcinoma (HNSCC).

Methods

The details of human cuproptosis and copper metabolism–related genes were searched and filtered from the msigdb database and the latest literature. To identify prognostic genes associated with cuproptosis and copper metabolism, we used least absolute shrinkage and selection operator regression, and this coefficient was used to set up a prognostic risk score model. HNSCC samples were divided into two groups according to the median risk. Afterwards, the function and immune characteristics of these genes in HNSCC were analyzed.

Results

The 14-gene signature was constructed to classify HNSCC patients into low-risk and high-risk groups according to the risk level. In the The Cancer Genome Atlas (TCGA) cohort, the overall survival (OS) rate of the high-risk group was lower than that of the low-risk group (P < 0.0001). The area under the curve of the time-dependent Receiver Operator Characteristic (ROC) curve assessed the good performance of the genetic signature in predicting OS and showed similar performance in the external validation cohort. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment assays and Protein-Protein Interaction (PPI) protein networks have been used to explore signaling pathways and potential mechanisms that were markedly active in patients with HNSCC. Furthermore, the 14 cuproptosis and copper metabolism-related genes were significantly correlated with the immune microenvironment, suggesting that these genes may be linked with the immune regulation and development of HNSCC.

Conclusions

Our results emphasize the significance of cuproptosis and copper metabolism as a predictive biomarker for HNSCC, and its expression levels seem to be correlated with immune- related features; thus, they may be a possible biomarker for HNSCC prognosis.

Radioimmunotherapy in HPV-Associated Head and Neck Squamous Cell Carcinoma

HPV-associated head and neck squamous cell carcinoma (HNSCC) is a cancer entity with unique biological and clinical characteristics that requires more personalized treatment strategies. As the backbone of conventional therapeutics, radiation is now harnessed to synergize with immunotherapy in multiple malignancies. Accumulating preclinical and clinical data have suggested the potential of radioimmunotherapy in eliciting local and systemic anti-tumor response via direct killing of tumor cells and immunogenic cell death. However, this effect remains uncertain in HPV-associated HNSCC. Owing to its intrinsic radiosensitivity and distinct tumor microenvironment, HPV-associated HNSCC may represent a good candidate for radioimmunotherapy. In this review, we provide a detailed illustration of the biology, the genomic features, and immune landscapes of HPV-associated HNSCC that support the synergism between radiation and immune agents. The interaction between radiotherapy and immunotherapy is described. We also highlight the present evidence as well as ongoing trials using different combination strategies in the recurrent/metastatic or definitive settings. In addition, we have summarized the challenges and outlook for future trial design, with special emphasis on radiotherapy optimization and novel therapeutic options to incorporate.

Neoadjuvant immunoradiotherapy in patients with locally advanced oral cavity squamous cell carcinoma: a retrospective study

BACKGROUND

Although anti-programmed death receptor-1 (PD-1) agents have been evaluated in the neoadjuvant setting for the treatment of locally advanced head and neck cancer, including oral cavity squamous cell carcinoma (OCSCC), the overall response rate is modest. The aim of the present study was to evaluate the efficacy and safety of neoadjuvant nivolumab in combination with stereotactic body radiotherapy (SBRT) for the treatment of locally advanced OCSCC.

METHODS

OCSCC patients who underwent surgical resection within 6 months of treatment with nivolumab plus SBRT from December 2018 to February 2021 were analyzed retrospectively.

RESULTS

All 30 eligible patients enrolled in this study well tolerated the neoadjuvant treatment with no serious adverse events (AEs). Of them, 27 patients (90.0%) achieved R0 resection, and 5 patients (16.7%) experienced procedure-associated complications. The complete response (CR), partial response (PR) and stable disease (SD) were 10.0%, 46.7% and 43.3% respectively. The major pathological response (MPR), complete pathological response (pCR) and clinical to pathological downstaging rate were 60.0%, 33.3% and 83.3% respectively. During the median follow-up period of 13.5 months, 26 patients (86.7%) who underwent surgical resection remained alive. The disease-free survival (DFS) and overall survival (OS) at 24 months were 70.4% and 76.4% respectively.

CONCLUSIONS

Neoadjuvant nivolumab plus SBRT is safe and efficacious, and could be used as a potential neoadjuvant option for the treatment of patients with locally advanced OCSCC.

Oligometastatic Head and Neck Cancer: Challenges and Perspectives

Simple Summary

Oligometastasis represents a disease state and an opportunity for cure when metastases emerge. Emerging evidence supports that most head and neck cancer patients with oligometastatic disease are likely to benefit from curative intent local ablative therapy if appropriate selection criteria are applied. Biomarkers to predict development of oligometastasis, as well as to identify which patients could benefit from a radical intent approach, are under investigation. This review summarizes recent knowledge about the characteristics, investigational efforts, and evidence for local ablation regarding oligometastasis in head and neck cancer. We also describe the challenges and opportunities in patient selection and discuss the role of radiotherapy and immunotherapy combinations to enhance anti-tumor immunity.

Abstract

A minority of patients with metastatic head and neck squamous cell carcinoma (HNSCC) present with oligometastatic disease. Oligometastasis not only reflects a disease state, but might also present an opportunity for cure in the metastatic setting. Radical ablation of all oligometastatic sites may confer prolonged survival and possibly achieve cure in some patients. However, substantial debate remains about whether patients with oligometastatic disease could benefit from curative intent therapy or whether aggressive treatments expose some patients to futile toxicity. Optimal selection of patients, carefully balancing the currently known prognostic factors against the risks of toxicity is critical. Emerging evidence suggests that patients with a limited burden of disease, viral-related pharyngeal cancer, metachronous metastasis and lung-only metastasis may benefit most from this approach. Efforts are underway to identify biomarkers that can detect oligometastasis and better select patients who would derive the maximum benefit from an aggressive radical approach. The combination of radiotherapy and immunotherapy promises to enhance the anti-tumoral immune response and help overcome resistance. However, optimization of management algorithms, including patient selection, radiation dose and sequencing, will be critical in upcoming clinical trials. This review summarizes recent knowledge about the characteristics and investigational efforts regarding oligometastasis in HNSCC.

Modeling of radiation effects to immune system: a review

Cancer metastasis is the major cause of cancer mortality and accounts for about 90% of cancer death. Although radiation therapy has been considered to reduce the localized cancer burden, emerging evidence that radiation can potentially turn tumors into an in situ vaccine has raised significant interest in combining radiation with immunotherapy. However, the combination approach might be limited by the radiation-induced immunosuppression. Assessment of radiation effects on the immune system at the patient level is critical to maximize the systemic antitumor response of radiation. In this review, we summarize the developed solutions in three different categories for systemic radiation therapy: blood dose, radiation-induced lymphopenia, and tumor control. Furthermore, we address how they could be combined to optimize radiotherapy regimens and maximize their synergy with immunotherapy.

Synergistic effects of radiotherapy and targeted immunotherapy in improving tumor treatment efficacy: a review

Radiotherapy (RT), unlike chemotherapy, is one of the most routinely used and effective genotoxic and immune response inducing cancer therapies with an advantage of reduced side effects. However, cancer can relapse after RT owing to multiple factors, including acquired tumor resistance, immune suppressive microenvironment buildup, increased DNA repair, thus favoring tumor metastasis. Efforts to mitigate these undesirable effects have drawn interest in combining RT with immunotherapy, particularly the use of immune checkpoint inhibitors, to tilt the pre-existing tumor stromal microenvironment into long-lasting therapy-induced antitumor immunity at multiple metastatic sites (abscopal effects). This multimodal therapeutic strategy can alleviate the increased T cell priming and decrease tumor growth and metastasis, thus emerging as a significant approach to sustain as long-term antitumor immunity. To understand more about this synergism, a detailed cellular mechanism underlying the dynamic interaction between tumor and immune cells within the irradiated tumor microenvironment needs to be explored. Hence, in the present review, we have attempted to evaluate various RT-inducible immune factors, which can be targeted by immunotherapy and provide detailed explanation to optimally maximize their synergy with immunotherapy for long-lasting antitumor immunity. Moreover, we have critically assessed various combinatorial approaches along with their challenges and described strategies to modify them in addition to providing approaches for optimal synergistic effects of the combination.

The oligometastatic spectrum in the era of improved detection and modern systemic therapy

Metastases remain the leading cause of cancer-related mortality. The oligometastasis hypothesis postulates that a spectrum of metastatic spread exists and that some patients with a limited burden of metastases can be cured with ablative therapy. Over the past decade, substantial advances in systemic therapies have resulted in considerable improvements in the outcomes of patients with metastatic cancers, warranting re-examination of the oligometastatic paradigm and the role of local ablative therapies within the context of the improved therapeutic responses, shifting patterns of disease recurrence and possible synergy with systemic treatments. Herein, we reframe the oligometastatic phenotype as a dynamic state for which locally ablative, metastasis-directed therapy improves clinical outcomes, including by prolonging survival and increasing cure rates. Important risk factors defining the metastatic spectrum are highlighted that inform both staging and therapy. Finally, we synthesize the literature on combining local therapies with modern systemic treatments, identifying general themes to optimally integrate ablative therapies in this context.

PRaG Therapy of Refractory Metastatic Gastric Cancer: A Case Report

Patients with metastatic gastric cancer had limited treatments and often had a somber prognosis, especially when patients were unable to tolerate high-intensity cytotoxic treatment due to poor physical condition or organ dysfunction after the failure of standard therapy. Here, we reported a metastatic and proficient mismatch repair (pMMR) gastric adenocarcinoma patient with the Eastern Cooperative Oncology Group (ECOG) performance status score of 2 associated with hypoproteinemia and fatigue, and poor appetite that was unable to tolerate high-intensity therapy after several chemotherapy regimens and anti-angiogenic therapy. After receiving novel triple-combination therapy, which consists of PD-1 inhibitor, Radiotherapy and Granulocyte-macrophage colony-stimulating factor (GM-CSF) therapy (PRaG for short), the patient achieved a complete response (CR) with a progression-free survival time of 14 months, and ECOG performance status score improved from 2 to 0. A significant systemic effect was observed in this case and the PRaG triple-combination therapy might provide a novel treatment strategy for metastatic pMMR gastric cancer patients.

A Pilot Study of Durvalumab (MEDI4736) with Tremelimumab in Combination with Image-Guided Stereotactic Body Radiotherapy in the Treatment of Metastatic Anaplastic Thyroid Cancer

Background: Metastatic anaplastic thyroid cancer (ATC) has a poor prognosis. This pilot study aims to evaluate tremelimumab plus durvalumab with stereotactic body radiotherapy (SBRT) to improve overall survival (OS). Methods: Eligible patients received up to 4 doses tremelimumab (75 mg) given q4 weeks and up to 1 year of durvalumab (1500 mg) given q4 weeks. SBRT at 9 Gy × 3 fractions was given within the first 2 weeks of the start of treatment. Paired biopsies (pretreatment and between 3 and 10 weeks after the first dose of the drug treatment) were done in the medically qualified patients. Major inclusion criteria are metastatic ATC, Eastern Cooperative Oncology Group (ECOG) performance status 0-2, no prior immunotherapy, and last anticancer treatment >7 days before starting the study. The primary endpoint was 1 year OS with the combination of durvalumab, tremelimumab, and SBRT in metastatic ATC patients with a target of 1 year OS in ≥2 out of 12 patients. Results: A total of 13 patients signed consent but only 12 patients ultimately participated in this trial. One patient who consented to the protocol became ineligible for this study due to continued decline in performance status. Patient characteristics were as follows: male (n = 6) with a median age of 71 years (range: 49-82), and ECOG = 1. Nine patients had prior neck radiation and nine patients had prior chemotherapy. Next-generation sequencing and PD-L1 staining were done in the nine patients where tissue was available. High microsatellite instability (MSI) corresponding to mismatch repair defect was noted in two patients. There were zero confirmed responses and only one patient had stable disease and was treated with ≥4 cycles of study drugs. The median time that the patients were under treatment was 11 weeks (1-28 weeks). MSI status did not affect treatment response. High MSI patients were on treatment for 8-14 weeks before disease progression. The median OS was 14.5 weeks with only 1 patient alive beyond 1 year. The presence of a BRAF or p53 mutation did not appear to affect treatment outcome. Conclusions: Tremelimumab and durvalumab with SBRT did not improve OS for ATC. Future research is needed to examine other novel immunotherapy combinations with or without radiotherapy in the treatment of ATC. Clinical Trial Registration: NCT03122496.

Safety and Tolerability of Metastasis Directed Radiotherapy in the Era of Evolving Systemic, Immune and Targeted Therapies

AbstractPurpose

Systemic, immune, and target therapies are growing in use in the management of metastatic cancers. The aim of this review was to describe up-to-date published data on the safety and tolerability of metastasis-directed hypofractionated radiation therapy (RT) when combined with newer systemic, immune, and targeted therapies and to provide suggested strategies to mitigate potential toxicities in the clinical setting.

Methods and Materials

A comprehensive search was performed for the time period between 1946 and August 2021 using predetermined keywords describing the use of noncentral nervous system palliative RT with commonly used targeted systemic therapies on PubMed and Medline databases. A total of 1022 articles were screened, and 130 met prespecified criteria to be included in this review.

Results

BRAF and MEK inhibitors are reported to be toxic when given concurrently with RT; suspension 3 days and 1 to 2 days, respectively, prior and post-RT is suggested. Cetuximab, erlotinib/gefitinib, and osimertinib were generally safe to use concomitantly with conventional radiation. But in a palliative/hypofractionated RT setting, suspending cetuximab during radiation week, erlotinib/gefitinib 1 to 2 days, and osimertinib ≥2 days pre- and post-RT is suggested. Vascular endothelial growth factor inhibitors such as bevacizumab reported substantial toxicities, and the suggestion is to suspend 4 weeks before and after radiation. Less data exist on sorafenib and sunitinib; 5 to 10 days suspension before and after RT should be considered. As a precaution, until further data are available, for cyclin-dependent kinase 4-6 inhibitors, consideration of suspending treatment 1 to 2 days before and after RT should be given. Ipilimumab should be suspended 2 days before and after RT, and insufficient data exist for other immunotherapy agents. Trastuzumab and pertuzumab are generally safe to use in combination with RT, but insufficient data exist for other HER2 target therapy.

Conclusions

Suggested approaches are described, using up-to-date literature, to aid clinicians in navigating the integration of newer targeted agents with hypofractionated palliative and/or ablative metastatic RT. Further prospective studies are required.

Practice changing data and emerging concepts from recent radiation therapy randomised clinical trials

INTRODUCTION

Oncology treatments are constantly and rapidly evolving. We aimed at highlighting the latest radiation therapy practice changing trials and emerging concepts, through an overview of recent randomised clinical trials (RCTs).

MATERIALS AND METHODS

Requests were performed in the Medline database to identify all publications reporting radiation therapy RCTs from 2018 to 2021.

RESULTS

Recent RCTs sustained the role of newer combinatorial strategies through radioimmunotherapy for early stage or metastatic lung cancer, newer pro-apoptotic agents (e.g. debio 1143 in locoregionally advanced head and neck squamous cell carcinoma) or nanoparticles (e.g. NBTXR3 in locally advanced soft-tissue sarcoma). High-tech radiotherapy allows intensifying treatments and gaining ground in some indications through the development of stereotactic body radiotherapy for example. First randomised evidence on personalised radiation therapy through imaging-based (¹⁸FDG positron emission tomography-computed tomography for lung cancer or early stage unfavourable Hodgkin lymphoma, PMSA positron emission tomography-computed tomography or magnetic resonance imaging for high-risk prostate cancer) or biological biomarkers (PSA for prostate cancer, HPV for head and neck cancer, etc) were conducted to more tailored treatments, with more favourable outcomes. Patients' quality of life and satisfaction appeared to be increasing aims. RCTs have validated (ultra)hypofractionated schemes in many indications as for breast, prostate or rectal cancer, resulting in equivalent outcomes and toxicities, more convenient for patients and favouring shared decision making.

CONCLUSION

Radiation therapy is a dynamic field of research, and many RCTs have greatly impacted therapeutic standards over the last years. Investments in radiotherapy research should facilitate the transfer of innovation to clinic.

Clinical evidence for synergy between immunotherapy and radiotherapy (SITAR)

Previous preclinical and clinical trials have shown promising antitumour activity and toxicity profile when employing the 'Synergy between Immunotherapy and Radiotherapy' (SITAR) strategy. Approximately, one in seven radiation therapy studies currently recruiting is investigating SITAR. This article reviews the range of cancers known to respond to immunotherapy and publications analysing SITAR. It sets the background for work that needs to be done in future clinical trials. It also reviews the potential toxicities of immunotherapy and discusses areas where caution is required when combining treatments.

Computational discovery of small drug-like compounds as potential inhibitors of PD-1/PD-L1 interactions

The programmed cell death ligand protein 1 (PD-L1) is a strong immunosuppressive molecule that inactivates tumor-specific T cells by binding to the programmed cell death- 1 protein (PD-1). Cancer immunotherapy based on the monoclonal antibodies targeting the PD-1/PD-L1 pathway has demonstrated therapeutic responses without precedent over a wide range of cancers. However, the antibody-based immunotherapies have several limitations such as high production cost or the induction of severe immune-related adverse effects. Small-molecule inhibitors of the PD-1/PD-L1 pathway are a promising alternative or complementary therapeutic to antibodies. Currently, the field of developing anti-PD-1/PD-L1 small-molecule inhibitors is intensively explored. In the present study a pharmacophore model was generated based on previously developed compounds and their atomistic structures with the PD-L1 dimer. Structure-based affinity-based virtual screening of small-molecule inhibitors of the PD-1/PD-L1 pathway according to the pharmacophore model followed by a screening in terms of drug-likeness resulted in ten hit compounds of high affinity towards the PD-L1 dimer and the satisfaction to all of the drug-likeness rules. Molecular dynamics (MD) simulations showed that nine of ten compounds formed stable complexes with the PD-L1 dimer as evidenced by the analysis of MD trajectories. Molecular mechanics Poisson- Boltzmann surface area (MM-PBSA) calculation revealed very low binding energies (<-46 kcal/mol) for the interactions of these ligands with the PD-L1 dimer, suggesting that identified compounds may serve as good scaffolds for the design of novel agents of antitumor immunotherapy able to target the PD-1/PD-L1 interactionCommunicated by Ramaswamy H. Sarma.

Overcoming Immune Resistance With Radiation Therapy in Prostate Cancer

Prostate cancer is the second most common cancer in men and represents a significant healthcare burden worldwide. Therapeutic options in the metastatic castration-resistant setting remain limited, despite advances in androgen deprivation therapy, precision medicine and targeted therapies. In this review, we summarize the role of immunotherapy in prostate cancer and offer perspectives on opportunities for future development, based on current knowledge of the immunosuppressive tumor microenvironment. Furthermore, we discuss the potential for synergistic therapeutic strategies with modern radiotherapy, through modulation of the tumor microenvironment. Emerging clinical and pre-clinical data suggest that radiation can convert immune desert tumors into an inflamed immunological hub, potentially sensitive to immunotherapy.

Immune checkpoint inhibitors in head and neck squamous cell carcinoma: A systematic review of phase-3 clinical trials

BACKGROUND

The outcomes of patients diagnosed with head and neck squamous cell carcinoma (HNSCC) who are not candidates for local salvage therapy and of those diagnosed with recurrent or metastatic disease are dismal. A relatively new systemic therapy option that emerged in recent years in the treatment of advanced HNSCC is immunotherapy using immune checkpoint inhibitors (ICIs). The safety profile and anti-tumor activity of these agents demonstrated in early phase clinical trials paved the way to the initiation of several promising phase-3 trials in the field.

AIM

To evaluate the evidence on the effectiveness of ICIs in HNSCC, based on published phase-3 clinical trials.

METHODS

We searched PubMed, Cochrane Library, Embase, and Scopus to identify published literature evaluating immunotherapy using ICIs in recurrent or metastatic HNSCC (R/M HNSCC) and locally advanced head and neck squamous cell carcinoma (LAHNSCC). We used a combination of standardized search terms and keywords including head and neck squamous cell carcinoma, recurrent, metastatic, locally advanced, immunotherapy, immune checkpoint inhibitors, monoclonal antibodies, programmed cell death protein-1 (PD-1), programmed death-ligand 1 (PD-L1), cytotoxic T- lymphocyte associated protein-4 (CTLA-4), and phase-3 clinical trial. A sensitive search filter was used to limit our results to randomized controlled trials.

RESULTS

Five phase-3 clinical trials have reported the data on the effectiveness of immunotherapy in HNSCC so far: Four in R/M HNSCC and one in LAHNSCC. In patients with R/M HNSCC, anti-PD-1 agents nivolumab and pembrolizumab demonstrated improved survival benefits in the second-line treatment setting compared to the standard of care (standard single-agent systemic therapy). While the net gain in overall survival (OS) with nivolumab was 2.4 mo [hazard ratio (HR) = 0.69, P = 0.01], that with pembrolizumab was 1.5 mo (HR = 0.80 nominal P = 0.0161). The anti-PD-L1 agent durvalumab with or without the anti-cytotoxic T- lymphocyte associated protein-4 agent tremelimumab did not result in any beneficial outcomes. In the first-line setting, in R/M HNSCC, pembrolizumab plus platinum-based chemotherapy resulted in significant improvement in survival with a net gain in OS of 2.3 mo (HR = 0.77, P = 0.0034) in the overall population and a net gain in OS of 4.2 mo in the PD-L1 positive (combined positive score > 20) population compared to standard of care (EXTREME regime). In patients with PD-L1 positive R/M HNSCC, monotherapy with pembrolizumab also demonstrated statistically significant improvement in survival compared to EXTREME. In LAHNSCC, immunotherapy using avelumab (an anti-PD-L1 agent) along with standard chemoradiation therapy did not result in improved outcomes compared to placebo plus chemoradiation therapy.

CONCLUSION

Anti-PD-1 agents provide survival benefits in R/M HNSCC in the first and second-line settings, with acceptable toxicity profiles compared to standard therapy. There is no proven efficacy in the curative setting to date.

Current Therapy for Metastatic Head and Neck Cancer: Evidence, Opportunities, and Challenges

Management of metastatic head and neck squamous cell carcinoma is evolving as new systemic therapies have led to improvements in survival, and as advances in locoregional therapy and the increased numbers of patients with HPV-associated cancers who develop oligometastases raise the possibility of ablation of limited numbers of metastases. We review the data regarding first-line immunotherapy in PD-L1-expressing metastatic head and neck squamous cell carcinoma, the experience with aggressive local management of oligometastases, and promising novel immunotherapies, targeted therapies, and HPV-specific treatments. For patients with metastatic head and neck squamous cell carcinoma that is PD-L1 expressing, first-line systemic therapy is pembrolizumab or pembrolizumab with chemotherapy. Inclusion of chemotherapy is associated with higher objective response proportion in all biomarker subgroups and may have a greater impact on survival in HPV-associated cancers. For patients with oligometastatic disease, particularly when metastases are metachronous, current evidence supporting the role of local ablation is limited to a small number of retrospective studies. Based on retrospective data, patients with a smaller number of metastases, lung metastases, and/or virally associated head and neck squamous cell carcinoma are most likely to benefit from an aggressive ablative approach. Additionally, we review emerging evidence for targeted therapy in metastatic head and neck squamous cell carcinoma, including with agents that inhibit mutant HRAS or NOTCH1, or overexpressed EGFR. Studies of antiangiogenic agents in combination with immune checkpoint blockade, and combination immunotherapy, are also under study.