PD-L1 blockade enhances response of pancreatic ductal adenocarcinoma to radiotherapy

Understanding the PULSAR effect in combined radiotherapy and immunotherapy using transformer-based attention mechanisms

PULSAR (personalized, ultra-fractionated stereotactic adaptive radiotherapy) is the adaptation of stereotactic ablative radiotherapy towards personalized cancer management. It has potential to harness the synergy between radiation therapy and immunotherapy, such as immune checkpoint inhibitors to amplify the anti-tumor immune response. For the first time, we applied a transformer-based attention mechanism to investigate the underlying interactions between combined PULSAR and PD-L1 blockade immunotherapy, based on the preliminary experimental results of a murine cancer model (Lewis Lung Carcinoma, LLC). The radiation and administration of α-PD-L1 were viewed as two external stimulation signals occurring in a temporal sequence. Our study demonstrates the utility of a transformer model in 1) predicting tumor changes in response to specific treatment schemes, and 2) generating self-attention and cross-attention maps. The cross-attention maps serve as a biological representation of the semantic similarity between source and target sentences in neural translation, offering insights into the causal relationships of the PULSAR effect. Our model offers a unique perspective with the potential to enhance the understanding of the temporal dependencies of the PULSAR effect on time, dose, and T cell dynamics. In a broader context, our proposed framework offers the potential to explore varying intervals and doses for subsequent treatments while monitoring the biological parameters impacted by these perturbations. This approach can lead to more personalized and rational radiation or drug interactions.

Optimizing neoadjuvant radiotherapy for locally advanced esophageal squamous cell carcinoma: a comprehensive review on the role of concomitant or sequential immune checkpoint inhibitors

Esophageal squamous cell carcinoma (ESCC) is a prevalent form of esophageal cancer with a poor prognosis despite advances in treatment. Combining immune checkpoint inhibitors (ICIs) with radiotherapy (RT) or chemoradiotherapy (CRT) has shown potential in enhancing treatment efficacy. We conducted a comprehensive review of clinical trials published between 2019 and 2024, sourced from PubMed, Scopus, and Embase databases. Studies included were prospective phase II trials that evaluated the combination of ICIs with neoadjuvant chemoradiotherapy (nCRT) in resectable locally advanced ESCC. Ten trials met the inclusion criteria. The review highlights various approaches in combining ICIs with CRT, including concurrent, induction, and consolidation therapy. Among the included trials, a significant proportion focused on concurrently administering ICIs with CRT, showing promising outcomes with high pathological complete response rates (pCR) and manageable toxicities. However, further research is needed to validate the efficacy of induction and consolidation therapies and determine optimal treatment protocols. The combination of ICIs and nCRT can potentially improve treatment responses and outcomes for patients with locally advanced ESCC. Despite recent encouraging findings, most trials were single-arm with small sample sizes, indicating the need for larger studies with longer follow-ups to assess survival outcomes comprehensively.

Phase 1 Study of Adjuvant Allogeneic Granulocyte-Macrophage Colony-Stimulating Factor-Transduced Pancreatic Tumor Cell Vaccine, Low-Dose Cyclophosphamide, and Stereotactic Body Radiation Therapy Followed by FOLFIRINOX in High-Risk Resected Pancreatic Ductal Adenocarcinoma

PURPOSE

Local and distant progression remains common following resection of resectable pancreatic ductal adenocarcinoma (PDAC) despite adjuvant multiagent chemotherapy. We report a prospective institutional phase 1 trial incorporating adjuvant GVAX vaccine, low-dose cyclophosphamide (Cy), and stereotactic body radiation therapy (SBRT) followed by FOLFIRINOX (FFX) among patients who underwent resection of high-risk PDAC.

PATIENTS AND METHODS

The study design was a modified 3+3. Cohort 1 received 5-fraction SBRT to 33 Gy to the tumor bed and 25 Gy to elective nodes followed by 6 cycles of full-dose FFX. After toxicity review, cohort 2 had SBRT and was switched to modified FFX (mFFX). Cohort 3 had 1 cycle of Cy/GVAX followed by SBRT, mFFX, and 4 cycles of maintenance Cy/GVAX with 6-month Cy/GVAX boosts until progression.

RESULTS

Nineteen patients were enrolled with a median follow-up of 36.2 months. To be eligible, patients were required to have close/positive margins (within ≤1 mm) (71%) and/or lymph node metastasis (79%). Overall, 63% of patients had both. In cohort 1, 67% of patients received 6 cycles of FFX; in cohort 2, 75% received 6 cycles of modified FFX. In cohort 3, 12 patients received the first dose of Cy/GVAX and SBRT with 10 individuals (83%) receiving 6 cycles of mFFX. Cohort 3 had acceptable levels of grade ≥3 thrombocytopenia, neutropenia, and diarrhea after 2 cycles of mFFX. Median overall survival (OS)/disease-free survival (DFS) for the overall cohort and cohort 3 was 36.2/18.2 months and 61.3/24.1 months, respectively. One- and 2-year OS for cohort 3 was 83%/75%, respectively. At the last follow-up (median = x), 5 patients were alive (42%) in cohort 3.

CONCLUSIONS

This is the first prospective trial to evaluate adjuvant GVAX, Cy, SBRT, and mFFX in resected PDAC patients with high-risk features. This combination regimen was well tolerated with limited toxicity and promising survival outcomes, warranting future studies to validate this regimen in the adjuvant setting.

Protocol digest of a randomized phase III trial comparing S-1-based chemoradiotherapy with/without nivolumab for unresectable locally advanced or borderline resectable pancreatic cancer: JCOG1908E (PENETRATE)

Pancreatic cancer remains a highly lethal disease with a 5-year survival proportion of <10%. Chemoradiotherapy is a treatment option for unresectable locally advanced (UR-LA) or borderline resectable (BR) pancreatic cancer, but its efficacy is not sufficient. Induction of the synergistic effect of irradiation and immune checkpoint inhibitors can be an attractive strategy. An open-label randomized phase III trial has been conducted since October 2020 to confirm the superiority of nivolumab plus S-1-based chemoradiotherapy over S-1-based chemoradiotherapy alone in patients with UR-LA or BR pancreatic cancer. A total of 216 patients will be enrolled in 14 institutions within 3.5 years. The primary endpoint of the safety run-in part is dose-limiting toxicity, and that of the phase III part is overall survival. This trial was registered at the Japan Registry of Clinical Trials as jRCT2080225361 (https://jrct.niph.go.jp/latest-detail/jRCT2080225361).

Cytosolic nucleic acid sensors and interferon beta-1 activation drive radiation-induced anti-tumour immune effects in human pancreatic cancer cells

Introduction

Pancreatic ductal adenocarcinoma (PDAC) remains a leading cause of cancer-related deaths worldwide with limited treatment options due to extensive radiation and chemotherapy resistance. Monotherapy with immune checkpoint blockade showed no survival benefit. A combination of immunomodulation and radiotherapy may offer new treatment strategies, as demonstrated for non-small cell lung cancer. Radiation-induced anti-tumour immunity is mediated through cytosolic nucleic acid sensing pathways that drive the expression of interferon beta-1 (IFNB1) and proinflammatory cytokines.

Methods

Human PDAC cell lines (PANC-1, MIA PaCa-2, BxPC-3) were treated with X-rays and protons. Immunogenic cell death was measured based on HMGB1 release. Cytosolic dsDNA and dsRNA were analysed by immunofluorescence microscopy. Cell cycle progression, MHC-I and PD-L1 expression were determined by flow cytometry. Galectin-1 and IFNB1 were measured by ELISA. The expression levels and the phosphorylation status of the cGAS/STING and RIG-I/MAVS signalling pathways were analysed by western blotting, the expression of IFNB1 and proinflammatory cytokines was determined by RT-qPCR and genome-wide by RNA-seq. CRISPR-Cas9 knock-outs and inhibitors were used to elucidate the relevance of STING, MAVS and NF-κB for radiation-induced IFNB1 activation.

Results

We demonstrate that a clinically relevant X-ray hypofractionation regimen (3x8 Gy) induces immunogenic cell death and activates IFNB1 and proinflammatory cytokines. Fractionated radiation induces G2/M arrest and accumulation of cytosolic DNA in PDAC cells, which partly originates from mitochondria. RNA-seq analysis shows a global upregulation of type I interferon response and NF-κB signalling in PDAC cells following 3x8 Gy. Radiation-induced immunogenic response is regulated by STING, MAVS and NF-κB. In addition to immunostimulation, radiation also induces immunosuppressive galectin-1. No significant changes in MHC-I or PD-L1 expression were observed. Moreover, PDAC cell lines show similar radiation-induced immune effects when exposed to single-dose protons or photons.

Conclusion

Our findings provide a rationale for combinatorial radiation-immunomodulatory treatment approaches in PDAC using conventional photon-based or proton beam radiotherapy.

Mathematical modeling and analysis of cancer treatment with radiation and anti-PD-L1

In cancer treatment, radiation therapy (RT) induces direct tumor cell death due to DNA damage, but it also enhances the deaths of radiosensitive immune cells and is followed by local relapse and up-regulation of immune checkpoint ligand PD-L1. Since the binding between PD-1 and PD-L1 curtails anti-tumor immunities, combining RT and PD-L1 inhibitor, anti-PD-L1, is a potential method to improve the treatment efficacy by RT. Some experiments support this hypothesis by showing that the combination of ionizing irradiation (IR) and anti-PD-L1 improves tumor reduction comparing to the monotherapy of IR or anti-PD-L1. In this work, we create a simplified ODE model to study the order of tumor growths under treatments of IR and anti-PD-L1. Our synergy analysis indicates that both IR and anti-PD-L1 improve the tumor reduction of each other, when IR and anti-PD-L1 are given simultaneously. When giving IR and anti-PD-L1 separately, a high dosage of IR should be given first to efficiently reduce tumor load and then followed by anti-PD-L1 with strong efficacy to maintain the tumor reduction and slow down the relapse. Increasing the duration of anti-PD-L1 improves the tumor reduction, but it cannot prolong the duration that tumor relapses to the level of the control case. Under some simplification, we also prove that the model has an unstable tumor free equilibrium and a locally asymptotically stable tumor persistent equilibrium. Our bifurcation diagram reveals a transition from tumor elimination to tumor persistence, as the tumor growth rate increases. In the tumor persistent case, both anti-PD-L1 and IR can reduce tumor amount in the long term.

Radiation and Melanoma: Where Are We Now?

PURPOSE OF REVIEW

This review summarizes the current role of radiotherapy for the treatment of cutaneous melanoma in the definitive, adjuvant, and palliative settings, and combinations with immunotherapy and targeted therapies.

RECENT FINDINGS

Definitive radiotherapy may be considered for lentigo maligna if surgery would be disfiguring. High risk, resected melanoma may be treated with adjuvant radiotherapy, but the role is poorly defined since the advent of effective systemic therapies. For patients with metastatic disease, immunotherapy and targeted therapies can be delivered safely in tandem with radiotherapy to improve outcomes. Radiotherapy and modern systemic therapies act in concert to improve outcomes, especially in the metastatic setting. Further prospective data is needed to guide the use of definitive radiotherapy for lentigo maligna and adjuvant radiotherapy for high-risk melanoma in the immunotherapy era. Current evidence does not support an abscopal response or at least identify the conditions necessary to reliably produce one with combinations of radiation and immunotherapy.

[18F]FMISO-PET imaging reveals the role of hypoxia severity in checkpoint blockade response

CONTEXT

Hypoxia within the tumor microenvironment is a critical factor influencing the efficacy of immunotherapy, including immune checkpoint inhibition. Insufficient oxygen supply, characteristic of hypoxia, has been recognized as a central determinant in the progression of various cancers. The reemergence of evofosfamide, a hypoxia-activated prodrug, as a potential treatment strategy has sparked interest in addressing the role of hypoxia in immunotherapy response. This investigation sought to understand the kinetics and heterogeneity of tumor hypoxia and their implications in affecting responses to immunotherapeutic interventions with and without evofosfamide.

PURPOSE

This study aimed to investigate the influence of hypoxia on immune checkpoint inhibition, evofosfamide monotherapy, and their combination on colorectal cancer (CRC). Employing positron emission tomography (PET) imaging, we developed novel analytical methods to quantify and characterize tumor hypoxia severity and distribution.

PROCEDURES

Murine CRC models were longitudinally imaged with [18F]-fluoromisonidazole (FMISO)-PET to quantify tumor hypoxia during checkpoint blockade (anti-CTLA-4 + and anti-PD1 +/- evofosfamide). Metrics including maximum tumor [18F]FMISO uptake (FMISOmax) and mean tumor [18F]FMISO uptake (FMISOmean) were quantified and compared with normal muscle tissue (average muscle FMISO uptake (mAvg) and muscle standard deviation (mSD)). Histogram distributions were used to evaluate heterogeneity of tumor hypoxia.

FINDINGS

Severe hypoxia significantly impeded immunotherapy effectiveness consistent with an immunosuppressive microenvironment. Hypoxia-specific PET imaging revealed a striking degree of spatial heterogeneity in tumor hypoxia, with some regions exhibiting significantly more severe hypoxia than others. The study identified FMISOmax as a robust predictor of immunotherapy response, emphasizing the impact of localized severe hypoxia on tumor volume control during therapy. Interestingly, evofosfamide did not directly reduce hypoxia but markedly improved the response to immunotherapy, uncovering an alternative mechanism for its efficacy.

CONCLUSIONS

These results enhance our comprehension of the interplay between hypoxia and immune checkpoint inhibition within the tumor microenvironment, offering crucial insights for the development of personalized cancer treatment strategies. Non-invasive hypoxia quantification through molecular imaging evaluating hypoxia severity may be an effective tool in guiding treatment planning, predicting therapy response, and ultimately improving patient outcomes across diverse cancer types and tumor microenvironments. It sets the stage for the translation of these findings into clinical practice, facilitating the optimization of immunotherapy regimens by addressing tumor hypoxia and thereby enhancing the efficacy of cancer treatments.

Combining immunotherapy and radiation therapy in gastrointestinal cancers: A review

INTRODUCTION AND PURPOSE

With a significant global impact, treatment of gastrointestinal (GI) cancers still presents with challenges, despite current multimodality approaches in advanced stages. Clinical trials are expanding for checkpoint inhibition (ICI) combined with radiation therapy (RT). This review intends to offer a comprehensive image of the current data regarding the effectiveness of this association, and to reflect on possible directions to further optimize the results.

RESULTS

Several early phase studies demonstrated encouraging potential. However, translating preclinical outcomes to clinical settings proves challenging, especially in immunologically "cold" environments. GI cancers exhibit heterogeneity, requiring tailored approaches based on disease stage and patient characteristics. Current results, though promising, lack the power of evidence to influence the general practice.

CONCLUSIONS

Finding biomarkers for identifying or converting resistant cancers is essential for maximizing responses, moreover in this context strategic RT parameters need to be carefully considered. Our review emphasizes the significance of having a thorough grasp of how immunology, tumour biology, and treatment settings interact in order to propose novel research avenues and efficient GI cancer therapy.

Treatment strategies and molecular mechanism of radiotherapy combined with immunotherapy in colorectal cancer

Radiotherapy (RT) remodels the tumor immune microenvironment (TIME) and modulates the immune response to indirectly destroy tumor cells, in addition to directly killing tumor cells. RT combined with immunotherapy may significantly enhance the efficacy of RT in colorectal cancer by modulating the microenvironment. However, the molecular mechanisms by which RT acts as an immunomodulator to modulate the immune microenvironment remain unclear. Further, the optimal modalities of RT combined with immunotherapy for the treatment of colorectal cancer, such as the time point of combining RT and immunization, the fractionation pattern and dosage of radiotherapy, and other methods to improve the efficacy, are also being explored parallelly. To address these aspects, in this review, we summarized the mechanisms by which RT modulates TIME and concluded the progress of RT combined with immunization in preclinical and clinical trials. Finally, we discussed heavy ion radiation therapy and the efficacy of prediction markers and other immune combination therapies. Overall, combining RT with immunotherapy to enhance antitumor effects will have a significant clinical implication and will help to facilitate individualized treatment modalities.

The double life of a chemotherapy drug: Immunomodulatory functions of gemcitabine in cancer

Although the development of immunotherapies has been revolutionary in the treatment of several cancers, many cancer types remain unresponsive to immune-based treatment and are largely managed by chemotherapy drugs. However, chemotherapeutics are not infallible and are frequently rendered ineffective as resistance develops from prolonged exposure. Recent investigations have indicated that some chemotherapy drugs have additional functions beyond their normative cytotoxic capacity and are in fact immune-modifying agents. Of the pharmaceuticals with identified immune-editing properties, gemcitabine is well-studied and of interest to clinicians and scientists alike. Gemcitabine is a chemotherapy drug approved for the treatment of multiple cancers, including breast, lung, pancreatic, and ovarian. Because of its broad applications, relatively low toxicity profile, and history as a favorable combinatory partner, there is promise in the recharacterization of gemcitabine in the context of the immune system. Such efforts may allow the identification of suitable immunotherapeutic combinations, wherein gemcitabine can be used as a priming agent to improve immunotherapy efficacy in traditionally insensitive cancers. This review looks to highlight documented immunomodulatory abilities of one of the most well-known chemotherapy agents, gemcitabine, relating to its influence on cells and proteins of the immune system.

An AI-based approach for modeling the synergy between radiotherapy and immunotherapy

Personalized, ultra-fractionated stereotactic adaptive radiotherapy (PULSAR) is designed to administer tumoricidal doses in a pulsed mode with extended intervals, spanning weeks or months. This approach leverages longer intervals to adapt the treatment plan based on tumor changes and enhance immune-modulated effects. In this investigation, we seek to elucidate the potential synergy between combined PULSAR and PD-L1 blockade immunotherapy using experimental data from a Lewis Lung Carcinoma (LLC) syngeneic murine cancer model. Employing a long short-term memory (LSTM) recurrent neural network (RNN) model, we simulated the treatment response by treating irradiation and anti-PD-L1 as external stimuli occurring in a temporal sequence. Our findings demonstrate that: (1) The model can simulate tumor growth by integrating various parameters such as timing and dose, and (2) The model provides mechanistic interpretations of a "causal relationship" in combined treatment, offering a completely novel perspective. The model can be utilized for in-silico modeling, facilitating exploration of innovative treatment combinations to optimize therapeutic outcomes. Advanced modeling techniques, coupled with additional efforts in biomarker identification, may deepen our understanding of the biological mechanisms underlying the combined treatment.

Nifuroxazide suppresses PD-L1 expression and enhances the efficacy of radiotherapy in hepatocellular carcinoma

Radiation therapy is a primary treatment for hepatocellular carcinoma (HCC), but its effectiveness can be diminished by various factors. The over-expression of PD-L1 has been identified as a critical reason for radiotherapy resistance. Previous studies have demonstrated that nifuroxazide exerts antitumor activity by damaging the Stat3 pathway, but its efficacy against PD-L1 has remained unclear. In this study, we investigated whether nifuroxazide could enhance the efficacy of radiotherapy in HCC by reducing PD-L1 expression. Our results showed that nifuroxazide significantly increased the sensitivity of tumor cells to radiation therapy by inhibiting cell proliferation and migration while increasing apoptosis in vitro. Additionally, nifuroxazide attenuated the up-regulation of PD-L1 expression induced by irradiation, which may be associated with increased degradation of PD-L1 through the ubiquitination-proteasome pathway. Furthermore, nifuroxazide greatly enhanced the efficacy of radiation therapy in H22-bearing mice by inhibiting tumor growth, improving survival, boosting the activation of T lymphocytes, and decelerating the ratios of Treg cells in spleens. Importantly, nifuroxazide limited the increased expression of PD-L1 in tumor tissues induced by radiation therapy. This study confirms, for the first time, that nifuroxazide can augment PD-L1 degradation to improve the efficacy of radiation therapy in HCC-bearing mice.

Overcoming the limitations of immunotherapy in pancreatic ductal adenocarcinoma: Combining radiotherapy and metabolic targeting therapy

As a novel anticancer therapy, immunotherapy has demonstrated robust efficacy against a few solid tumors but poor efficacy against pancreatic ductal adenocarcinoma (PDAC). This poor outcome is primarily attributable to the intrinsic cancer cell resistance and T-cell exhaustion, which is also the reason for the failure of conventional therapy. The present review summarizes the current PDAC immunotherapy avenues and the underlying resistance mechanisms. Then, the review discusses synergistic combination therapies, such as radiotherapy (RT) and metabolic targeting. Research suggests that RT boosts the antigen of PDAC, which facilitates the anti-tumor immune cell infiltration and exerts function. Metabolic reprogramming contributes to restoring the exhausted T cell function. The current review will help in tailoring combination regimens to enhance the efficacy of immunotherapy. In addition, it will help provide new approaches to address the limitations of the immunosuppressive tumor microenvironment (TME) by examining the relationship among immunotherapy, RT, and metabolism targeting therapy in PDAC.

Neoadjuvant radioimmunotherapy in pancreatic cancer enhances effector T cell infiltration and shortens their distances to tumor cells

Radiotherapy is hypothesized to have an immune-modulating effect on the tumor microenvironment (TME) of pancreatic ductal adenocarcinoma (PDAC) to sensitize it to anti-PD-1 antibody (a-PD-1) treatment. We collected paired pre- and posttreatment specimens from a clinical trial evaluating combination treatment with GVAX vaccine, a-PD-1, and stereotactic body radiation (SBRT) following chemotherapy for locally advanced PDACs (LAPC). With resected PDACs following different neoadjuvant therapies as comparisons, effector cells in PDACs were found to skew toward a more exhausted status in LAPCs following chemotherapy. The combination of GVAX/a-PD-1/SBRT drives TME to favor antitumor immune response including increased densities of GZMB+CD8+ T cells, TH1, and TH17, which are associated with longer survival, however increases immunosuppressive M2-like tumor-associated macrophages (TAMs). Adding SBRT to GVAX/a-PD-1 shortens the distances from PD-1+CD8+ T cells to tumor cells and to PD-L1+ myeloid cells, which portends prolonged survival. These findings have guided the design of next radioimmunotherapy studies by targeting M2-like TAM in PDACs.

Local ablative therapies and the effect on antitumor immune responses in pancreatic cancer - A review

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease, projected to rank as the second most prevalent cause of cancer-related mortality by 2030. Despite significant progress in advances in surgical techniques and chemotherapy protocols, the overall survival (OS) remains to be less than 10 % for all stages combined. In recent years, local ablative techniques have been introduced and utilized as additional therapeutic approaches for locally advanced pancreatic cancer (LAPC), with promising results with respect to local tumor control and OS. In addition to successful cytoreduction, there is emerging evidence that local ablation induces antitumor immune activity that could prevent or even treat distant metastatic tumors. The enhancement of antitumor immune responses could potentially make ablative therapy a therapeutic option for the treatment of metastatic PDAC. In this review, we summarize current ablative techniques used in the management of LAPC and their impact on systemic immune responses.

Combining cisplatin and a STING agonist into one molecule for metalloimmunotherapy of cancer

Mounting evidence suggests that strategies combining DNA-damaging agents and stimulator of interferon genes (STING) agonists are promising cancer therapeutic regimens because they can amplify STING activation and remodel the immunosuppressive tumor microenvironment. However, a single molecular entity comprising both agents has not yet been developed. Herein, we designed two PtIV-MSA-2 conjugates (I and II) containing the DNA-damaging chemotherapeutic drug cisplatin and the innate immune-activating STING agonist MSA-2; these conjugates showed great potential as multispecific small-molecule drugs against pancreatic cancer. Mechanistic studies revealed that conjugate I upregulated the expression of transcripts associated with innate immunity and metabolism in cancer cells, significantly differing from cisplatin and MSA-2. An analysis of the tumor microenvironment demonstrated that conjugate I could enhance the infiltration of natural killer (NK) cells into tumors and promote the activation of T cells, NK cells and dendritic cells in tumor tissues. These findings indicated that conjugate I, which was created by incorporating a Pt chemotherapeutic drug and STING agonist into one molecule, is a promising and potent anticancer drug candidate, opening new avenues for small-molecule-based cancer metalloimmunotherapy.

Recent progress, perspectives, and issues of engineered PD-L1 regulation nano-system to better cure tumor: A review

Currently, immune checkpoint blockade (ICB) therapies that target the programmed cell death ligand-1 (PD-L1) have been used as revolutionary cancer treatments in the clinic. Apart from restoring the antitumor response of cytotoxic T cells by blocking the interaction between PD-L1 on tumor cells and programmed cell death-1 (PD-1) on T cells, PD-L1 proteins were also newly revealed to possess the capacity to accelerate DNA damage repair (DDR) and enhance tumor growth through multiple mechanisms, leading to the impaired efficacy of tumor therapies. Nevertheless, current free anti-PD-1/PD-L1 therapy still suffered from poor therapeutic outcomes in most solid tumors due to the non-selective tumor accumulation, ineludible severe cytotoxic effects, as well as the common occurrence of immune resistance. Recently, nanoparticles with efficient tumor-targeting capacity, tumor-responsive prosperity, and versatility for combination therapy were identified as new avenues for PD-L1 targeting cancer immunotherapies. In this review, we first summarized the multiple functions of PD-L1 protein in promoting tumor growth, accelerating DDR, as well as depressing immunotherapy efficacy. Following this, the effects and mechanisms of current clinically widespread tumor therapies on tumor PD-L1 expression were discussed. Then, we reviewed the recent advances in nanoparticles for anti-PD-L1 therapy via using PD-L1 antibodies, small interfering RNA (siRNA), microRNA (miRNA), clustered, regularly interspaced, short palindromic repeats (CRISPR), peptide, and small molecular drugs. At last, we discussed the challenges and perspectives to promote the clinical application of nanoparticles-based PD-L1-targeting therapy.

Immune profiling of pancreatic cancer for radiotherapy with immunotherapy and targeted therapy: Biomarker analysis of a randomized phase 2 trial

PURPOSE

Immunotherapy alone offered limited survival benefits in pancreatic cancer, while the role of immunotherapy-centric combined therapy remains controversial. Therefore, it is required to develop biomarkers to precisely deliver immunotherapy-based multimodality for pancreatic cancer.

METHODS

This is a secondary analysis of an open label, randomized, phase 2 trial, whereas patients with locally recurrent pancreatic cancer after surgery were enrolled. Eligible patients with mutant KRAS and positive immunohistochemical staining of PD-L1 were randomly assigned to receive stereotactic body radiation therapy (SBRT) plus pembrolizumab and trametinib (SBRT + K + M) or SBRT and gemcitabine (SBRT + G). Meanwhile, patients were classified into PD-L1+/tumor infiltrating lymphocytes [TIL(s)]- and PD-L1+/TIL + group for each arm.

RESULTS

A total of 170 patients were enrolled and randomly assigned to receive SBRT + K + M (n = 85) or SBRT + G (n = 85). The improved outcomes have been reported in patients with SBRT + K + M in the previous study. In this secondary analysis, the median overall survival (OS) was 17.2 months (95% CI 14.6-19.8 months) in patients with PD-L1+/TIL + and 12.7 months (95% CI 10.8-14.6 months) in patients with PD-L1+/TIL- (HR 0.62, 95% CI 0.39-0.97, p = 0.036) receiving SBRT + K + M. In SBRT + G group, the median OS was 13.1 months (95% CI 10.9-15.3 months) in patients with PD-L1+/TIL- and 12.7 months (95% CI 9.2-16.2 months) in patients with PD-L1+/TIL+ (HR 0.97, 95% CI 0.62-1.52, p = 0.896). Grade 3 or 4 adverse events were found in 16 patients (30.8%) and 10 patients (30.3%) with PD-L1+/TIL- and PD-L1+/TIL + in SBRT + K + M group respectively; whereas 9 (16.7%) and 8 patients (25.8%) with PD-L1+/TIL- and PD-L1+/TIL + in SBRT + G group.

CONCLUSION

PD-L1, TILs and mutant KRAS may be a biomarker to guide clinical practice of radiotherapy and immunotherapy-based regimens in pancreatic cancer if further combined with MEK inhibitors as targeted therapy.

Statins abrogate gemcitabine-induced PD-L1 expression in pancreatic cancer-associated fibroblasts and cancer cells with improved therapeutic outcome

A combination of chemotherapy with immunotherapy has been proposed to have better clinical outcomes in Pancreatic Ductal Adenocarcinoma (PDAC). On the other hand, chemotherapeutics is known to have certain unwanted effects on the tumor microenvironment that may mask the expected beneficial effects of immunotherapy. Here, we have investigated the effect of gemcitabine (GEM), on two immune checkpoint proteins (PD-L1 and PD-L2) expression in cancer associated fibroblasts (CAFs) and pancreatic cancer cells (PCCs). Findings of in vitro studies conducted by using in-culture activated mouse pancreatic stellate cells (mPSCs) and human PDAC patients derived CAFs demonstrated that GEM significantly induces PD-L1 and PD-L2 expression in these cells. Moreover, GEM induced phosphorylation of STAT1 and production of multiple known PD-L1-inducing secretory proteins including IFN-γ in CAFs. Upregulation of PD-L1 in PSCs/CAFs upon GEM treatment caused T cell inactivation and apoptosis in vitro. Importantly, Statins suppressed GEM-induced PD-L1 expression both in CAFs and PCCs while abrogating the inactivation of T-cells caused by GEM-treated PSCs/CAFs. Finally, in an immunocompetent syngeneic orthotopic mouse pancreatic tumor model, simvastatin and GEM combination therapy significantly reduced intra-tumor PD-L1 expression and noticeably reduced the overall tumor burden and metastasis incidence. Together, the findings of this study have provided experimental evidence that illustrates potential unwanted side effects of GEM that could hamper the effectiveness of this drug as mono and/or combination therapy. At the same time the findings also suggest use of statins along with GEM will help in overcoming these shortcomings and warrant further clinical investigation.

Modulation of CD8+ T Cell Responses by Radiotherapy-Current Evidence and Rationale for Combination with Immune Checkpoint Inhibitors

Radiotherapy for cancer has been known to affect the responses of immune cells, especially those of CD8+ T cells that play a pivotal role in anti-tumor immunity. Clinical success of immune checkpoint inhibitors led to an increasing interest in the ability of radiation to modulate CD8+ T cell responses. Recent studies that carefully analyzed CD8+ T cell responses following radiotherapy suggest the beneficial roles of radiotherapy on anti-tumor immunity. In addition, numerous clinical trials to evaluate the efficacy of combining radiotherapy with immune checkpoint inhibitors are currently undergoing. In this review, we summarize the current status of knowledge regarding the changes in CD8+ T cells following radiotherapy from various preclinical and clinical studies. Furthermore, key biological mechanisms that underlie such modulation, including both direct and indirect effects, are described. Lastly, we discuss the current evidence and essential considerations for harnessing radiotherapy as a combination partner for immune checkpoint inhibitors.

Cytomorphologic, immunophenotypical and molecular features of pancreatic acinar cell carcinoma

OBJECTIVES

As a rare tumor in pancreas, pancreatic acinar cell carcinoma (PACC) possesses a distinct molecular feature from pancreatic ductal carcinoma (PDAC). Though the diagnosis of PACC is often established based on cytology specimens, its cytologic diagnosis can be challenging. Furthermore, the correlation between PACC cytomorphology and its unique different molecular alterations have not been fully explored.

METHODS

Cytology features were analyzed in 8 histologically proven PACC and cytohistological correlation was performed. Immunocytochemistry for trypsin, chymotrypsin, BCL10, synaptophysin, chromogranin A, INSM1, β-catenin, and Ki-67 was assessed. Comprehensive molecular profiling and additional targetable treatment biomarker assessment were also performed.

RESULTS

The cohort included 4 mixed acinar-neuroendocrine carcinomas, 3 pure PACCs, and 1 mixed acinar-ductal carcinoma. Immunophenotypical features are consistent with diagnoses of PACC or PACC with neuroendocrine features. Identified genetic alterations included somatic mutations of CTNNB1, TP53, MAP2K1, PTEN, RAC1, germline mutations of NBN and BRAC2, and gene fusion of CCDC6-RET.

CONCLUSIONS

The current study is the first attempt to explore the correlation between the cytomorphology characteristics and molecular features of PACC and a few intriguing findings were observed. Further validation in larger cohorts is warranted.

Radiotherapy remodels the tumor microenvironment for enhancing immunotherapeutic sensitivity

Cancer immunotherapy has transformed traditional treatments, with immune checkpoint blockade being particularly prominent. However, immunotherapy has minimal benefit for patients in most types of cancer and is largely ineffective in some cancers (such as pancreatic cancer and glioma). A synergistic anti-tumor response may be produced through the combined application with traditional tumor treatment methods. Radiotherapy (RT) not only kills tumor cells but also triggers the pro-inflammatory molecules' release and immune cell infiltration, which remodel the tumor microenvironment (TME). Therefore, the combination of RT and immunotherapy is expected to achieve improved efficacy. In this review, we summarize the effects of RT on cellular components of the TME, including T cell receptor repertoires, different T cell subsets, metabolism, tumor-associated macrophages and other myeloid cells (dendritic cells, myeloid-derived suppressor cells, neutrophils and eosinophils). Meanwhile, non-cellular components such as lactate and extracellular vesicles are also elaborated. In addition, we discuss the impact of different RT modalities on tumor immunity and issues related to the clinical practice of combination therapy.

The Role of Immune Checkpoint Inhibitors in Metastatic Pancreatic Cancer: Current State and Outlook

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest tumors, characterized by its aggressive tumor biology and poor prognosis. While immune checkpoint inhibitors (ICIs) play a major part in the treatment algorithm of various solid tumors, there is still no evidence of clinical benefit from ICI in patients with metastatic PDAC (mPDAC). This might be due to several reasons, such as the inherent low immunogenicity of pancreatic cancer, the dense stroma-rich tumor microenvironment that precludes an efficient migration of antitumoral effector T cells to the cancer cells, and the increased proportion of immunosuppressive immune cells, such as regulatory T cells (Tregs), cancer-associated fibroblasts (CAFs), and myeloid-derived suppressor cells (MDSCs), facilitating tumor growth and invasion. In this review, we provide an overview of the current state of ICIs in mPDAC, report on the biological rationale to implement ICIs into the treatment strategy of pancreatic cancer, and discuss preclinical studies and clinical trials in this field. Additionally, we shed light on the challenges of implementing ICIs into the treatment strategy of PDAC and discuss potential future directions.

Radiotherapy Combination: Insight from Tumor Immune Microenvironment (TIME)

The view of Radiotherapy (RT) as a simple inducer of DNA damage resulting in tumor cell death has dramatically changed in recent years, and it is now widely accepted that RT can trigger an immune response which provides a sound basis for combining RT with immunotherapy. Given that, radiation can be delivered with different regimens, its effect on immune responses and Tumor Immune Microenvironment (TIME) may vary with dose and fractionation schedule. This fractional dose dependency may need to be more considered because of recent developments in RT delivery techniques making it possible to deliver precisely higher dosages per fraction (hypofractionation) while reducing exposure to normal tissues. Although combining radiotherapy with immunotherapy could be a promising strategy for synergistic enhancement of treatment efficacy, the selection of the best-matched combination of immunotherapy with each radiotherapy scheme remains to be addressed. Thus, for designing better therapeutic combinations, it is necessary to understand the immunological effects of RT. Here, we review the impact of conventional and different hypofractionation radiation schedules on the TIME. Subsequently, we highlight how knowing about these interactions may have implications for choosing a rational combination with targeted therapies.

Advances in Immunotherapeutics in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) accounts for up to 95% of all pancreatic cancer cases and is the seventh-leading cause of cancer death. Poor prognosis is a result of late presentation, a lack of screening tests and the fact some patients develop resistance to chemotherapy and radiotherapy. Novel therapies like immunotherapeutics have been of recent interest in pancreatic cancer. However, this field remains in its infancy with much to unravel. Immunotherapy and other targeted therapies have yet to yield significant progress in treating PDAC, primarily due to our limited understanding of the disease immune mechanisms and its intricate interactions with the tumour microenvironment (TME). In this review we provide an overview of current novel immunotherapies which have been studied in the field of pancreatic cancer. We discuss their mechanisms, evidence available in pancreatic cancer as well as the limitations of such therapies. We showcase the potential role of combining novel therapies in PDAC, postulate their potential clinical implications and the hurdles associated with their use in PDAC. Therapies discussed with include programmed death checkpoint inhibitors, Cytotoxic T-lymphocyte-associated protein 4, Chimeric Antigen Receptor-T cell therapy, oncolytic viral therapy and vaccine therapies including KRAS vaccines, Telomerase vaccines, Gastrin Vaccines, Survivin-targeting vaccines, Heat-shock protein (HSP) peptide complex-based vaccines, MUC-1 targeting vaccines, Listeria based vaccines and Dendritic cell-based vaccines.

Adaptation of the Tumor Antigen Presentation Machinery to Ionizing Radiation

Ionizing radiation (IR) can reprogram proteasome structure and function in cells and tissues. In this article, we show that IR can promote immunoproteasome synthesis with important implications for Ag processing and presentation and tumor immunity. Irradiation of a murine fibrosarcoma (FSA) induced dose-dependent de novo biosynthesis of the immunoproteasome subunits LMP7, LMP2, and Mecl-1, in concert with other changes in the Ag-presentation machinery (APM) essential for CD8+ T cell-mediated immunity, including enhanced expression of MHC class I (MHC-I), β2-microglobulin, transporters associated with Ag processing molecules, and their key transcriptional activator NOD-like receptor family CARD domain containing 5. In contrast, in another less immunogenic, murine fibrosarcoma (NFSA), LMP7 transcripts and expression of components of the immunoproteasome and the APM were muted after IR, which affected MHC-I expression and CD8+ T lymphocyte infiltration into NFSA tumors in vivo. Introduction of LMP7 into NFSA largely corrected these deficiencies, enhancing MHC-I expression and in vivo tumor immunogenicity. The immune adaptation in response to IR mirrored many aspects of the response to IFN-γ in coordinating the transcriptional MHC-I program, albeit with notable differences. Further investigations showed divergent upstream pathways in that, unlike IFN-γ, IR failed to activate STAT-1 in either FSA or NFSA cells while heavily relying on NF-κB activation. The IR-induced shift toward immunoproteasome production within a tumor indicates that proteasomal reprogramming is part of an integrated and dynamic tumor-host response that is specific to the stressor and the tumor and therefore is of clinical relevance for radiation oncology.

Concurrent/sequential versus sequential immune checkpoint inhibition in inoperable large stage III non-small cell lung cancer patients treated with chemoradiotherapy: a prospective observational study

PURPOSE/AIM

The international standard for patients with large inoperable stage III NSCLC is durvalumab consolidation after concurrent chemoradiotherapy (CRT). In this single centre observational study based on individual data, we prospectively evaluated the role of concurrent/sequential versus sequential immune checkpoint inhibition (ICI).

METHODS AND PATIENTS

In total, 39 stage III NSCLC patients were prospectively enrolled, 11 (28%) patients were treated with simultaneous and consolidation therapy with PD-1 inhibition (nivolumab) (SIM-cohort) and 28 (72%) patients received PD-L1 inhibition (durvalumab) as consolidation treatment up to 12 months after the end of CRT (SEQ-cohort).

RESULTS

For the entire cohort, median progression-free survival (PFS) was 26.3 months and median survival (OS), locoregional recurrence-free survival and distant metastasis-free survival were not reached. For the SIM-cohort, median OS was not reached and PFS was 22.8 months, respectively. In the SEQ-cohort, neither median PFS nor OS were reached. After propensity score matching, PFS at 12/24 months were 82/44% in the SIM-cohort and 57/57% in the SEQ-cohort (p = 0.714), respectively. In the SIM-cohort, 36.4/18.2% of patients showed grade II/III pneumonitis; in the SEQ-cohort 18.2/13.6% after PSM (p = 0.258, p = 0.55).

CONCLUSION

Both concurrent/sequential and sequential ICI show a favorable side effect profile and promising survival in treated patients with inoperable large stage III NSCLC. Concurrent ICI showed a numerical non-significant improvement regarding 6- and 12-months PFS and distant control compared to sequential approach in this small study. However, concurrent ICI to CRT was associated with a non-significant moderate increase in grade II/III pneumonitis.

Immune modulation during anti-cancer radio(immuno)therapy

Cancer can affect all human organs and tissues and ranks as a prominent cause of death as well as an obstruction to increasing life expectancy. A notable breakthrough in oncology has been the inclusion of the immune system in fighting cancer, potentially prolonging life and providing long-term benefits. The concept of "immunotherapy" has been discussed from the 19th and early 20th centuries by Wilhelm Busch, William B. Coley and Paul Ehrlich. This involves distinct approaches, including vaccines, non-specific cytokines and adoptive cell therapies. However, despite the advances made in recent years, questions on how to select the best therapeutic options or how to select the best combinations to improve clinical outcomes are still relevant for scientists and clinicians. More than half of cancer patients receive radiotherapy (RT) as part of their treatment. With the advances in RT and immunotherapy approaches, it is reasonable to consider how to enhance immunotherapy with radiation and vice versa, and to investigate whether combinations of these therapies would be beneficial. In this chapter, we will discuss how the immune system responds to cancer cells and different cancer therapies with a focus on combination of RT and immunotherapy (radioimmunotherapy, RIT).

Yes-Associated Protein 1 Inhibition Induces Immunogenic Cell Death and Synergizes With Radiation and PD-1 Blockade

PURPOSE

Danger signals released by ionizing radiation (IR) can theoretically stimulate immune activation in the tumor environment (TME), but IR alone is not sufficient to induce an effective immune response in clinical practice. In this study, we investigated whether inhibition of yes-associated protein 1 (YAP1) could induce immunogenic cell death (ICD) and whether the combination of YAP1 inhibition with IR could increase in vivo immune infiltration and thereby boost a tumor response to immunotherapy.

METHODS AND MATERIALS

First, the expression of ICD markers, markers of T-cell activation, and key proteins involved in innate immune signaling were measured after YAP1 inhibition. Next, the expression level of YAP1 protein was measured after different doses of IR. Then, the antitumor effect of YAP1 inhibition combined with IR was investigated in vivo, and the immune status of the TME was evaluated. Finally, the efficacy of a triple therapy including YAP1 inhibition combined with IR and programmed cell death protein 1 blockade in the treatment of resistant tumors was determined.

RESULTS

We found that YAP1 inhibition induced ICD and increased the levels of antigen presentation machinery, effectively causing the activation of T cells. Mechanistically, YAP1 inhibition induced cell DNA damage and activated the cyclic GMP-AMP synthase (cGAS)/stimulator of interferon genes (STING) pathway. Surprisingly, IR upregulated YAP1 expression. IR combined with YAP1 inhibition significantly inhibited cancer growth and prolonged survival, which was related to the augmented infiltration, activation, and function of CD8+ T cells in the TME. Moreover, the addition of YAP1 inhibition significantly improved the efficacy of pancreatic cancer treatment when neither radiation nor programmed cell death protein 1 inhibitors were ideal.

CONCLUSIONS

YAP1 inhibition could trigger ICD and is a potential approach to potentiating the therapeutic efficacy of radiation therapy and anti-PD1 immunotherapy.

Ketoglutaric acid can reprogram the immunophenotype of triple-negative breast cancer after radiotherapy and improve the therapeutic effect of anti-PD-L1

BACKGROUND

Great progress has been made in applying immunotherapy to the clinical treatment of tumors. However, many patients with triple-negative breast cancer (TNBC) cannot benefit from immunotherapy due to the immune desert type of TNBC, which is unresponsive to immunotherapy. DMKG, a cell-permeable derivative of α-KG, has shown potential to address this issue.

METHOD

We investigated the effects of combining DMKG with radioimmunotherapy on TNBC. We assessed the ability of DMKG to promote tumor cell apoptosis and immunogenic death induced by radiotherapy (RT), as well as its impact on autophagy reduction, antigen and inflammatory factor release, DC cell activation, and infiltration of immune cells in the tumor area.

RESULT

Our findings indicated that DMKG significantly promoted tumor cell apoptosis and immunogenic death induced by RT. DMKG also significantly reduced autophagy in tumor cells, resulting in increased release of antigens and inflammatory factors, thereby activating DC cells. Furthermore, DMKG promoted infiltration of CD8 + T cells in the tumor area and reduced the composition of T-regulatory cells after RT, reshaping the tumor immune microenvironment. Both DMKG and RT increased the expression of PD-L1 at immune checkpoints. When combined with anti-PD-L1 drugs (α-PD-L1), they significantly inhibited tumor growth without causing obvious side effects during treatment.

CONCLUSION

Our study underscores the potential of pairing DMKG with radioimmunotherapy as an effective strategy for treating TNBC by promoting apoptosis, immunogenic death, and remodeling the tumor immune microenvironment. This combination therapy could offer a promising therapeutic avenue for TNBC patients unresponsive to conventional immunotherapy.

The immunogenic radiation and new players in immunotherapy and targeted therapy for head and neck cancer

Although treatment modalities for head and neck cancer have evolved considerably over the past decades, survival rates have plateaued. The treatment options remained limited to definitive surgery, surgery followed by fractionated radiotherapy with optional chemotherapy, and a definitive combination of fractionated radiotherapy and chemotherapy. Lately, immunotherapy has been introduced as the fourth modality of treatment, mainly administered as a single checkpoint inhibitor for recurrent or metastatic disease. While other regimens and combinations of immunotherapy and targeted therapy are being tested in clinical trials, adapting the appropriate regimens to patients and predicting their outcomes have yet to reach the clinical setting. Radiotherapy is mainly regarded as a means to target cancer cells while minimizing the unwanted peripheral effect. Radiotherapy regimens and fractionation are designed to serve this purpose, while the systemic effect of radiation on the immune response is rarely considered a factor while designing treatment. To bridge this gap, this review will highlight the effect of radiotherapy on the tumor microenvironment locally, and the immune response systemically. We will review the methodology to identify potential targets for therapy in the tumor microenvironment and the scientific basis for combining targeted therapy and radiotherapy. We will describe a current experience in preclinical models to test these combinations and propose how challenges in this realm may be faced. We will review new players in targeted therapy and their utilization to drive immunogenic response against head and neck cancer. We will outline the factors contributing to head and neck cancer heterogeneity and their effect on the response to radiotherapy. We will review in-silico methods to decipher intertumoral and intratumoral heterogeneity and how these algorithms can predict treatment outcomes. We propose that (a) the sequence of surgery, radiotherapy, chemotherapy, and targeted therapy should be designed not only to annul cancer directly, but to prime the immune response. (b) Fractionation of radiotherapy and the extent of the irradiated field should facilitate systemic immunity to develop. (c) New players in targeted therapy should be evaluated in translational studies toward clinical trials. (d) Head and neck cancer treatment should be personalized according to patients and tumor-specific factors.

Metabolic Intervention Liposome Boosted Lung Cancer Radio-Immunotherapy via Hypoxia Amelioration and PD-L1 Restraint

At present, radiotherapy (RT) still acquires limited success in clinical due to the lessened DNA damage under hypoxia and acquired immune tolerance owing to the amplified programmed death ligand-1 (PD-L1) expression. Incredibly, intracellular PD-L1 expression depression is proven to better sensitize RT by inhibiting DNA damage repair. However, the disability of the clinically used antibodies in disrupting the extracellular PD-L1function still limits the effectiveness of radio-immunotherapy. Therefore, better PD-L1 regulation strategies are still urgently needed to better sensitize radio-immunotherapy. Hence, for this purpose, TPP-LND is synthesized by linking mitochondrial-targeted triphenylphosphine cations (TPP+ ) to the antineoplastic agent lonidamine (LND), which significantly reduces the dose needed for LND to induce effective oxidative phosphorylation inhibition (2 vs 300 µM). Then, TPP-LND is wrapped with liposomes to form TPP-LND@Lip nanoparticles. By doing this, TPP-LND@Lip nanoparticles can sensitize RT by reversing the hypoxic microenvironment of tumors to generate more DNA damage and reducing the expression of PD-L1 via enhancing the adenosine 5'-monophosphate-activated protein kinase activation. As expected, these well-designed economical TPP-LND@Lip nanoparticles are more effective than conventional anti-PD-L1 antibodies to some extent.

Improving the efficacy of combined radiotherapy and immunotherapy: focusing on the effects of radiosensitivity

Cancer treatment is gradually entering an era of precision, with multitude studies in gene testing and immunotherapy. Tumor cells can be recognized and eliminated by the immune system through the expression of tumor-associated antigens, but when the cancer escapes or otherwise suppresses immunity, the balance between cancer cell proliferation and immune-induced cancer cell killing may be interrupted, resulting in tumor proliferation and progression. There has been significant attention to combining conventional cancer therapies (i.e., radiotherapy) with immunotherapy as opposed to treatment alone. The combination of radio-immunotherapy has been demonstrated in both basic research and clinical trials to provide more effective anti-tumor responses. However, the absolute benefits of radio-immunotherapy are dependent on individual characteristics and not all patients can benefit from radio-immunotherapy. At present, there are numerous articles about exploring the optimal models for combination radio-immunotherapy, but the factors affecting the efficacy of the combination, especially with regard to radiosensitivity remain inconclusive. Radiosensitivity is a measure of the response of cells, tissues, or individuals to ionizing radiation, and various studies have shown that the radiosensitivity index (RSI) will be a potential biomarker for predicting the efficacy of combination radio-immunotherapy. The purpose of this review is to focus on the factors that influence and predict the radiosensitivity of tumor cells, and to evaluate the impact and predictive significance of radiosensitivity on the efficacy of radio-immunotherapy combination.

Curcumin Enhances the Abscopal Effect in Mice with Colorectal Cancer by Acting as an Immunomodulator

Radiotherapy (RT) is an effective cancer treatment. The abscopal effect, referring to the unexpected shrinkage observed in non-irradiated tumors after radiation therapy, is thought to be mediated by systemic immune activation. However, it has low incidence and is unpredictable. Here, RT was combined with curcumin to investigate how curcumin affects RT-induced abscopal effects in mice with bilateral CT26 colorectal tumors. Indium 111-labeled DOTA-anti-OX40 mAb was synthesized to detect the activated T cell accumulations in primary and secondary tumors correlating with the changes in protein expressions and tumor growth to understand the overall effects of the combination of RT and curcumin. The combination treatment caused the most significant tumor suppression in both primary and secondary tumors, accompanied by the highest ¹¹¹In-DOTA-OX40 mAb tumor accumulations. The combination treatment elevated expressions of proapoptotic proteins (Bax and cleaved caspase-3) and proinflammatory proteins (granzyme B, IL-6, and IL-1β) in both primary and secondary tumors. Based on the biodistribution of ¹¹¹In-DOTA-OX40 mAb, tumor growth inhibition, and anti-tumor protein expression, our findings suggest that curcumin could act as an immune booster to augment RT-induced anti-tumor and abscopal effects effectively.

CAR T cell-based immunotherapy and radiation therapy: potential, promises and risks

CAR T cell-based therapies have revolutionized the treatment of hematological malignancies such as leukemia and lymphoma within the last years. In contrast to the success in hematological cancers, the treatment of solid tumors with CAR T cells is still a major challenge in the field and attempts to overcome these hurdles have not been successful yet. Radiation therapy is used for management of various malignancies for decades and its therapeutic role ranges from local therapy to a priming agent in cancer immunotherapy. Combinations of radiation with immune checkpoint inhibitors have already proven successful in clinical trials. Therefore, a combination of radiation therapy may have the potential to overcome the current limitations of CAR T cell therapy in solid tumor entities. So far, only limited research was conducted in the area of CAR T cells and radiation. In this review we will discuss the potential and risks of such a combination in the treatment of cancer patients.

CD73 and PD-L1 dual blockade amplifies antitumor efficacy of SBRT in murine PDAC models

BACKGROUND

Stereotactic body radiotherapy (SBRT) induces immunogenic cell death, leading to subsequent antitumor immune response that is in part counterbalanced by activation of immune evasive processes, for example, upregulation of programmed cell death-ligand 1 (PD-L1) and adenosine generating enzyme, CD73. CD73 is upregulated in pancreatic ductal adenocarcinoma (PDAC) compared with normal pancreatic tissue and high expression of CD73 in PDACs is associated with increased tumor size, advanced stage, lymph node involvement, metastasis, PD-L1 expression and poor prognosis. Therefore, we hypothesized that blockade of both CD73 and PD-L1 in combination with SBRT might improve antitumor efficacy in an orthotopic murine PDAC model.

METHODS

We assessed the combination of systemic blockade of CD73/PD-L1 and local SBRT on tumor growth in primary pancreatic tumors, and investigated systemic antitumor immunity using a metastatic murine model bearing both orthotopic primary pancreatic tumor and distal hepatic metastases. Immune response was quantified by flow cytometric and Luminex analyses.

RESULTS

We demonstrated that blockade of both CD73 and PD-L1 significantly amplified the antitumor effect of SBRT, leading to superior survival. The triple therapy (SBRT+anti-CD73+anti-PD-L1) modulated tumor-infiltrating immune cells with increases of interferon-γ+CD8+ T cells. Additionally, triple therapy reprogramed the profile of cytokines/chemokines in the tumor microenvironment toward a more immunostimulatory phenotype. The beneficial effects of triple therapy are completely abrogated by depletion of CD8+ T cells, and partially reversed by depletion of CD4+ T cells. Triple therapy promoted systemic antitumor responses illustrated by: (1) potent long-term antitumor memory and (2) enhanced both primary and liver metastases control along with prolonged survival.

Triple-Combination Immunogenic Nanovesicles Reshape the Tumor Microenvironment to Potentiate Chemo-Immunotherapy in Preclinical Cancer Models

Immune checkpoint blockade (ICB) therapies have had a tremendous impact on cancer therapy. However, most patients harbor a poorly immunogenic tumor microenvironment (TME), presenting overwhelming de novo refractoriness to ICB inhibitors. To address these challenges, combinatorial regimens that employ chemotherapies and immunostimulatory agents are urgently needed. Here, a combination chemoimmunotherapeutic nanosystem consisting of a polymeric monoconjugated gemcitabine (GEM) prodrug nanoparticle decorated with an anti-programmed cell death-ligand 1 (PD-L1) antibody (αPD-L1) on the surface and a stimulator of interferon genes (STING) agonist encapsulated inside is developed. Treatment with GEM nanoparticles upregulates PD-L1 expression in ICB-refractory tumors, resulting in augmented intratumor drug delivery in vivo and synergistic antitumor efficacy via activation of intratumor CD8+ T cell responses. Integration of a STING agonist into the αPD-L1-decorated GEM nanoparticles further improves response rates by transforming low-immunogenic tumors into inflamed tumors. Systemically administered triple-combination nanovesicles induce robust antitumor immunity, resulting in durable regression of established large tumors and a reduction in the metastatic burden, coincident with immunological memory against tumor rechallenge in multiple murine tumor models. These findings provide a design rationale for synchronizing STING agonists, PD-L1 antibodies, and chemotherapeutic prodrugs to generate a chemoimmunotherapeutic effect in treating ICB-nonresponsive tumors.

A Three-in-One Nanoscale Coordination Polymer for Potent Chemo-Immunotherapy

The addition of immune checkpoint blockade to standard chemotherapy has changed the standards of care for some cancer patients. However, current chemo-immunotherapy strategies do not benefit most colorectal cancer patients and many triple-negative breast cancer patients. Here, the design of a three-in-one nanoscale coordination polymer (NCP), OX/GC/CQ, comprising prodrugs of oxaliplatin (OX), gemcitabine (GC), and 5-carboxy-8-hydroxyquinoline (CQ) for triple-modality chemo-immunotherapy is reported. OX/GC/CQ exhibits optimal pharmacokinetics and enhanced particle accumulation and drug release in acidic tumor tissues, wherein CQ greatly enhances immunogenic cell death induced by OX/GC and downregulates programmed cell death-ligand 1  expression in cancer cells. Consequently, OX/GC/CQ efficiently promotes infiltration and activity of cytotoxic T lymphocytes, while decreasing the proportion of immunosuppressive regulatory T cells. Intravenous injection of OX/GC/CQ reduces the growth of colorectal carcinoma and triple-negative breast cancer, prevents metastasis to lungs, and extends mouse survival by 30-40 days compared to free drugs. This work highlights the potential of NCPs in co-delivering synergistic chemo-immunotherapeutics for the treatment of advanced and aggressive cancers.

New Treatment Options in Metastatic Pancreatic Cancer

Pancreatic cancer (PC) is the seventh leading cause of cancer death across the world. Poor prognosis of PC is associated with several factors, such as diagnosis at an advanced stage, early distant metastases, and remarkable resistance to most conventional treatment options. The pathogenesis of PC seems to be significantly more complicated than originally assumed, and findings in other solid tumours cannot be extrapolated to this malignancy. To develop effective treatment schemes prolonging patient survival, a multidirectional approach encompassing different aspects of the cancer is needed. Particular directions have been established; however, further studies bringing them all together and connecting the strengths of each therapy are needed. This review summarises the current literature and provides an overview of new or emerging therapeutic strategies for the more effective management of metastatic PC.

Harnessing the Immunological Effects of Radiation to Improve Immunotherapies in Cancer

Ionizing radiation (IR) is used to treat 50% of cancers. While the cytotoxic effects related to DNA damage with IR have been known since the early 20th century, the role of the immune system in the treatment response is still yet to be fully determined. IR can induce immunogenic cell death (ICD), which activates innate and adaptive immunity against the cancer. It has also been widely reported that an intact immune system is essential to IR efficacy. However, this response is typically transient, and wound healing processes also become upregulated, dampening early immunological efforts to overcome the disease. This immune suppression involves many complex cellular and molecular mechanisms that ultimately result in the generation of radioresistance in many cases. Understanding the mechanisms behind these responses is challenging as the effects are extensive and often occur simultaneously within the tumor. Here, we describe the effects of IR on the immune landscape of tumors. ICD, along with myeloid and lymphoid responses to IR, are discussed, with the hope of shedding light on the complex immune stimulatory and immunosuppressive responses involved with this cornerstone cancer treatment. Leveraging these immunological effects can provide a platform for improving immunotherapy efficacy in the future.

How to overcome resistance to immune checkpoint inhibitors in colorectal cancer: From mechanisms to translation

Immunotherapy, especially with immune checkpoint inhibitors (ICIs), has shown advantages in cancer treatment and is a new hope for patients who have failed multiline therapy. However, in colorectal cancer (CRC), the benefit is limited to a small subset of patients with microsatellite instability-high (MSI-H) or mismatch repair-deficient (dMMR) metastatic CRC (mCRC). In addition, 45% to 60% of dMMR/MSI-H mCRC patients showed primary or acquired resistance to ICIs. This means that these patients may have potential unknown pathways mediating immune escape. Almost all mismatch repair-proficient (pMMR) or microsatellite-stable (MSS) mCRC patients do not benefit from ICIs. In this review, we discuss the mechanisms of action of ICIs and their current status in CRC. We then discuss the mechanisms of primary and acquired resistance to ICIs in CRC. Finally, we discuss promising therapeutic strategies to overcome resistance to ICIs in the clinic.

Phase 2 study of ipilimumab, nivolumab, and tocilizumab combined with stereotactic body radiotherapy in patients with refractory pancreatic cancer (TRIPLE-R)

BACKGROUND

Interleukin-6 blockade and radiation combined with immunotherapy may modulate the tumour microenvironment to overcome immune resistance. We assessed the efficacy of ipilimumab, nivolumab, and tocilizumab combined with stereotactic body radiotherapy (SBRT) in patients with refractory pancreatic cancer (PC).

METHODS

Patients with PC who had progressive disease (PD) or intolerance to gemcitabine- or fluorouracil-containing regimens were enrolled in Part A of the two-part, single-centre, phase 2 study (NCT04258150). SBRT with 15 Gy was administered on day one of the first cycle. Ipilimumab was administered (1 mg/kg every 6 weeks) for a maximum of two infusions. Nivolumab (6 mg/kg) and tocilizumab (8 mg/kg) were given every four weeks until the PD or unacceptable toxicity, or for up to one year. The primary end-point was the objective response rate, with a threshold of 15%.

RESULTS

Twenty-six patients were enrolled and treated between April 17, 2020, and January 25, 2021. The median follow-up time at the time of data cutoff (February 7, 2022) was 4.9 months (interquartile range 2.1-7.7). No responses were observed. Five patients (19%; 95% confidence intervals [CI], 7-39) achieved a stable disease. The median progression-free survival was 1.6 months (95% CI 1.4-1.7), and the median overall survival was 5.3 months (95% CI 2.3-8.0). Overall, 19 (73%) experienced adverse events related to the treatment including two (8%) with grade 3 or higher events.

CONCLUSION

The combination of ipilimumab, nivolumab, tocilizumab, and SBRT in patients with PC did not meet the prespecified criteria for expansion for full accrual.

Profiling of a novel circadian clock-related prognostic signature and its role in immune function and response to molecular targeted therapy in pancreatic cancer

BACKGROUND

Pancreatic ductal adenocarcinoma (PADA) represents a devastating type of pancreatic cancer with high mortality. Defining a prognostic gene signature that can stratify patients with different risk will benefit cancer treatment strategies.

METHODS

Gene expression profiles of PADA patients were acquired from the Cancer Genome Atlas and Gene Expression Omnibus, including GSE62452 and GSE28735. Differential expression analysis was carried out using the package edgeR in R. Intro-tumor immune infiltrates were quantified by six different computational algorithms XCELL, TIMER, QUANTISEQ, MCPCOUNTER, EPIC, and CIBERSORT. Biological processes were investigated based on R package "clusterProfiler".

RESULTS

13 genes (ARNTL2, BHLHE40, FBXL17, FBXL8, PPP1CB, RBM4B, ADRB1, CCAR2, CDK1, CSNK1D, KLF10, PSPC1, SIAH2) were eligible for the development of a prognostic gene signature. Performance of the prognostic gene signature was assessed in the discovery set (n = 210), validation set (n = 52), and two external data set (GSE62452, n = 65, and GSE28735, n = 84). Area under the curve (AUC) for predicting 3-year overall survival was 0.727, 0.732, 0.700, and 0.658 in the training set, the validation set, and the two test sets, respectively. KM curve revealed that the low-risk group had an improved prognosis than the high-risk group in all four datasets. PCA analysis demonstrated that the low-risk group was apparently separated from the high-risk group. CD8 T cell and B cell were significantly reduced in the high-risk group than in the low-risk group, while neutrophils were significantly augmented in the high-risk group than in the low-risk group. BMS-536924, Foretinib, Linsitinib, and Sabutoclax were more sensitive in the low-risk group, whereas Erlotinib was more effective in the high-risk group.

CONCLUSIONS

We successfully established and verified a novel circadian clock-related gene signature, which could stratify patients with different risk and be reflective of the therapeutic effect of molecular targeted therapy. Our findings could incorporate the pharmacological modulation of circadian clock into future therapeutic strategies.

Stereotactic Body Radiotherapy and Immunotherapy for Older Patients with Oligometastases: A Proposed Paradigm by the International Geriatric Radiotherapy Group

The standard of care for metastatic disease is systemic therapy. A unique subset of patients with limited metastatic disease defined as distant involvement of five anatomic sites or less (oligometastases) have a better chance of remission or improved survival and may benefit from local treatments such as surgery or stereotactic body radiotherapy (SBRT). However, to prevent further spread of disease, systemic treatment such as chemotherapy, targeted therapy, and hormonal therapy may be required. Older patients (70 years old or above) or physiologically frail younger patients with multiple co-morbidities may not be able to tolerate the conventional chemotherapy due to its toxicity. In addition, those with a good performance status may not receive optimal chemotherapy due to concern about toxicity. Recently, immunotherapy with checkpoint inhibitors (CPI) has become a promising approach only in the management of program death ligand 1 (PD-L1)-positive tumors. Thus, a treatment method that elicits induction of PD-L1 production by tumor cells may allow all patients with oligometastases to benefit from immunotherapy. In vitro studies have demonstrated that high dose of radiotherapy may induce formation of PD-L1 in various tumors as a defense mechanism against inflammatory T cells. Clinical studies also corroborated those observations. Thus, SBRT, with its high precision to minimize damage to normal organs, may be a potential treatment of choice for older patients with oligometastases due to its synergy with immunotherapy. We propose a protocol combining SBRT to achieve a minimum radiobiologic equivalent dose around 59.5 Gy to all tumor sites if feasible, followed four to six weeks later by CPI for those cancer patients with oligometastases. All patients will be screened with frailty screening questionnaires to identify individuals at high risk for toxicity. The patients will be managed with an interdisciplinary team which includes oncologists, geriatricians, nurses, nutritionists, patient navigators, and social workers to manage all aspects of geriatric patient care. The use of telemedicine by the team may facilitate patient monitoring during treatment and follow-up. Preliminary data on toxicity, local control, survival, and progression-free survival may be obtained and serve as a template for future prospective studies.

Injectable versatile liquid-solid transformation implants alliance checkpoint blockade for magnetothermal dynamic-immunotherapy

The ongoing circulating energy loss, low reactive oxygen species (ROS) accumulation and poor immunogenicity of tumors make it difficult to induce sufficient immunogenic cell death (ICD) in the tumor immunosuppressive microenvironment (TIME), resulting in unsatisfactory immunotherapy efficacy. Furthermore, for highly malignant tumors, simply enhancing ICD is insufficient for exhaustively eliminating the tumor and inhibiting metastasis. Herein, we propose a unique magnetothermal-dynamic immunotherapy strategy based on liquid-solid transformation porous versatile implants (Fe₃O₄/AIPH@PLGA) that takes advantage of less energy loss and avoids ongoing circulating losses by minimally invasive injection into tumors. In addition, the magnetothermal effect regresses and eliminates tumors that are not limited by penetration to simultaneously trigger 2,2′-azobis[2-(2-imidazolin-2-yl) propane] dihydrochloride (AIPH) decomposition and generate a large amount of oxygen-irrelevant free radicals and heat shock protein (HSP) accumulation by heating, evoking both intracellular oxidative stress and endoplasmic reticulum (ER) stress to induce large-scale ICD and enhance tumor immunogenicity. More importantly, in orthotopic bilateral breast tumor models, a significant therapeutic effect was obtained after combining amplified ICD with CTLA4 checkpoint blockade. The 21-day primary and distant tumor inhibition rates reached 90%, and the underlying mechanism of the effective synergetic strategy of inducing the T-cell-related response, the immune memory effect and TIME reprogramming in vivo was verified by immune cell analyses. This remarkable therapeutic effect provides a new direction for antitumor immunotherapy based on magnetothermally controlled oxygen-independent free radical release.

•

Injectable versatile liquid-solid phase transformation Fe₃O₄/AIPH@PLGA gel implants are constructed for the first time.

•

The implants triggered magnetothermal dynamic therapy and successfully addressed two key barriers limiting the efficacy of immunogenic cell death (ICD): low reactive oxygen species (ROS) accumulation and poor immunogenicity.

•

The implants promoting DC maturation, recognition and presentation of antigens. Combined with CTLA4 blockade, the function of Treg cells was inhibited to transform the “cold” TIME into “hot”.

The poorly immunogenic tumor microenvironment of pancreatic cancer: the impact of radiation therapy, and strategies targeting resistance

Pancreatic cancer is one of the most lethal cancers, due to its uniquely aggressive behavior and resistance to therapy. The tumor microenvironment of pancreatic cancer is immunosuppressive, and attempts at utilizing immunotherapies have been unsuccessful. Radiation therapy (RT) results in immune activation and antigen presentation in other cancers, but in pancreatic cancer has had limited success in stimulating immune responses. RT activates common pathways of fibrosis and chronic inflammation seen in pancreatic cancer, resulting in immune suppression. Here we describe the pancreatic tumor microenvironment with regard to fibrosis, myeloid and lymphoid cells, and the impact of RT. We also describe strategies of targeting these pathways that have promise to improve outcomes by harnessing the cytotoxic and immune-activating aspects of RT.

Oncolytic virus-mediated reducing of myeloid-derived suppressor cells enhances the efficacy of PD-L1 blockade in gemcitabine-resistant pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is often refractory to treatment with gemcitabine (GEM) and immune checkpoint inhibitors including anti-programmed cell death ligand 1 (PD-L1) antibody. However, the precise relationship between GEM-resistant PDAC and development of an immunosuppressive tumor microenvironment (TME) remains unclear. In this study, we investigated the immunosuppressive TME in parental and GEM-resistant PDAC tumors and assessed the therapeutic potential of combination therapy with the telomerase-specific replication-competent oncolytic adenovirus OBP-702, which induces tumor suppressor p53 protein and PD-L1 blockade against GEM-resistant PDAC tumors. Mouse PDAC cells (PAN02) and human PDAC cells (MIA PaCa-2, BxPC-3) were used to establish GEM-resistant PDAC lines. PD-L1 expression and the immunosuppressive TME were analyzed using parental and GEM-resistant PDAC cells. A cytokine array was used to investigate the underlying mechanism of immunosuppressive TME induction by GEM-resistant PAN02 cells. The GEM-resistant PAN02 tumor model was used to evaluate the antitumor effect of combination therapy with OBP-702 and PD-L1 blockade. GEM-resistant PDAC cells exhibited higher PD-L1 expression and produced higher granulocyte-macrophage colony-stimulating factor (GM-CSF) levels compared with parental cells, inducing an immunosuppressive TME and the accumulation of myeloid-derived suppressor cells (MDSCs). OBP-702 significantly inhibited GEM-resistant PAN02 tumor growth by suppressing GM-CSF-mediated MDSC accumulation. Moreover, combination treatment with OBP-702 significantly enhanced the antitumor efficacy of PD-L1 blockade against GEM-resistant PAN02 tumors. The present results suggest that combination therapy involving OBP-702 and PD-L1 blockade is a promising antitumor strategy for treating GEM-resistant PDAC with GM-CSF-induced immunosuppressive TME formation.

Dynamic alterations in PD-1/PD-L1 expression level and immune cell profiles based on radiation response status in mouse tumor model

Introduction

Based on the immunologic effects of anti-cancer treatment and their therapeutic implications, we evaluated radiotherapy (RT)-induced dynamic alterations in programmed death-1 (PD-1)/PD ligand-1 (PD-L1) expression profiles.

Methods

Local RT with 2 Gy × 5 or 7.5 Gy × 1 was administered to the CT26 mouse model. Thereafter, tumors were resected and evaluated at the following predefined timepoints according to radiation response status: baseline, early (immediately after RT), middle (beginning of tumor shrinkage), late (stable status with RT effect), and progression (tumor regrowth). PD-1/PD-L1 activity and related immune cell profiles were quantitatively assessed.

Results

RT upregulated PD-L1 expression in tumor cells from the middle to late phase; however, the levels subsequently decreased to levels comparable to baseline in the progression phase. RT with 2 Gy × 5 induced a higher frequency of PD-L1+ myeloid-derived suppressor cells, with a lesser degree of tumor regression, compared to 7.5 Gy. The proportion of PD-1+ and interferon (IFN)-γ+CD8α T cells continued to increase. The frequency of splenic PD-1+CD8+ T cells was markedly elevated, and was sustained longer with 2 Gy × 5. Based on the transcriptomic data, RT stimulated the transcription of immune-related genes, leading to sequentially altered patterns.

Discussion

The dynamic alterations in PD-1/PD-L1 expression level were observed according to the time phases of tumor regression. This study suggests the influence of tumor cell killing and radiation dosing strategy on the tumor immune microenvironment.