Synergy of radiotherapy and PD-1 blockade in Kras-mutant lung cancer

Pre-existing intratumoral stem-like CD8+ T cells drive radiotherapy-induced tumor immunity

CD8+ T cells are crucial for both spontaneous and therapy-induced restriction of tumor progression. Although many patients with cancer undergo radiotherapy, the precise effect of this genotoxic treatment on tumor-associated CD8+ T cells is insufficiently understood. Here, we investigated the influence of radiotherapy on intratumoral CD8+ T cells. We found that, although these CD8+ T cells initially decline following radiotherapy, they subsequently expand and are both essential and sufficient for early tumor control. In response to radiotherapy, stem-like CD8+ T cells proliferate and differentiate into effector CD8+ T cells, making them key drivers of tumor immunity. Our findings underscore the pivotal role of intratumoral stem-like CD8+ T cells in mediating radiotherapy-induced anti-tumor immunity and provide deeper insights into the dynamic behavior of CD8+ T cells during tumor control after radiotherapy.

IDO1 inhibitor enhances the effectiveness of PD-1 blockade in microsatellite stable colorectal cancer by promoting macrophage pro-inflammatory phenotype polarization

Microsatellite stable (MSS) colorectal cancer (CRC) is a subtype of CRC that generally exhibits resistance to immunotherapy, particularly immune checkpoint inhibitors such as PD-1 blockade. This study investigates the effects and underlying mechanisms of combining PD-1 blockade with IDO1 inhibition in MSS CRC. Bioinformatics analyses of TCGA-COAD and TCGA-READ cohorts revealed significantly elevated IDO1 expression in CRC tumors, correlating with tumor mutation burden across TCGA datasets. In vivo experiments demonstrated that the combination of IDO1 inhibition and PD-1 blockade significantly reduced tumor growth and increased immune cell infiltration, particularly pro-inflammatory macrophages and CD8+ T cells. IDO1 knockdown in CRC cell lines impaired tolerance to interferon-γ and increased apoptosis in vitro, which were rescued by the application of kynurenine, the end product of IDO1. IDO1 knockdown in MSS CRC enhanced the effectiveness of PD-1 blockade therapy in vivo. IDO1 knockdown cancer cells promoted pro-inflammatory macrophage polarization and enhanced phagocytic activity in vitro, associated with the upregulation of JAK2-STAT3-IL6 signaling pathway. These findings highlight the role of IDO1 in modulating the tumor immune microenvironment in MSS CRC and suggest that combining PD-1 blockade with IDO1 inhibition could enhance therapeutic efficacy by promoting macrophage pro-inflammatory polarization and infiltration through the JAK2-STAT3-IL6 pathway.

The Optimal Radiotherapy Strategy for Patients With Small Cell Lung Cancer and Brain Metastasis: A Retrospective Analysis

BACKGROUND

Extensive-stage small cell lung cancer (ES-SCLC) is a notoriously aggressive malignancy frequently associated with brain metastases (BMs), presenting substantial therapeutic challenges. This study delves into the effectiveness of immunotherapy combined with diverse radiotherapy, especially the influence of brain radiotherapy (BRT) on survival outcomes in the immunotherapy era.

METHODS

ES-SCLC patients treated at Xiangya Hospital and Xiangya Boai Hospital from February 2020 to June 2024 were retrospectively included. The study focused on patients receiving immune checkpoint inhibitors (ICIs). Metrics included overall survival (OS) and progression-free survival (PFS), employing univariate and multivariate Cox regression models for statistical analysis.

RESULTS

A total of 393 patients with ES-SCLC who received ICIs were included in the study. Within the entire cohort, the presence of baseline BMs did not statistically affect OS or PFS. However, thoracic radiotherapy (TRT) was identified as a favorable prognostic factor for both OS and PFS. BRT demonstrated a beneficial effect on OS across both the general cohort and the baseline_BMs subgroup. In patients from the baseline_BMs subgroup who had previously undergone TRT, ICIs plus BRT did not significantly improve OS compared to ICIs alone. Conversely, for patients who had not received prior TRT, adding BRT to ICIs significantly enhanced OS. Among the patients who underwent BRT, 71 received whole brain radiotherapy (WBRT) while 19 opted for stereotactic radiosurgery (SRS). No significant differences in OS and PFS were observed between the SRS and WBRT modalities. The sequence of ICIs relative to BRT was found to influence PFS adversely. Administering BRT before ICIs (RT-ICI) was associated with worse PFS compared to administering ICIs followed by BRT (ICI-RT). Additionally, no significant differences in OS and PFS were noted among the three subgroups defined by varying intervals between ICIs and BRT. For patients without baseline BMs, TRT and prophylactic cranial irradiation were associated with delayed onset of brain metastases.

CONCLUSIONS

Our study underscores the importance of optimizing treatment strategies and considering the timing and integration of radiotherapy and immunotherapy to improve outcomes for patients with ES-SCLC, particularly those at risk of or presenting with BMs.

Definitive chemoradiotherapy induces T-cell-inflamed tumor microenvironment in unresectable locally advanced esophageal squamous cell carcinoma

BACKGROUND

Chemoradiotherapy (CRT) modulates the tumor immune microenvironment of multiple cancer types, including esophageal cancer, which potentially induces both immunogenicity and immunosuppression by upregulating the presentation of tumor-specific antigens and immune checkpoint molecules in tumors, respectively. The prognostic effects of immune modification by CRT in esophageal squamous cell carcinoma (ESCC) remain controversial because of the lack of detailed immunological analyses using paired clinical specimens before and after CRT. We aimed to clarify the immunological changes in the tumor microenvironment caused by CRT and elucidate the predictive importance of clinical response and prognosis and the rationale for the necessity of subsequent programmed cell death protein 1 (PD-1) inhibitor treatment.

METHODS

In this study, we performed a comprehensive immunological analysis of paired biopsy specimens using multiplex immunohistochemistry before and after CRT in patients with unresectable locally advanced ESCC.

RESULTS

CRT significantly increased the intra-tumoral infiltration and PD-1 expression of CD8+ T cells and conventional CD4+ T cells but decreased those of regulatory T cells and the accumulation of tumor-associated macrophages. Multivariate analysis of tumor-infiltrating T-cell phenotypes revealed that the density of PD-1+CD8+ T cells in the tumor after CRT could predict a confirmed complete response and favorable survival.

CONCLUSIONS

This study showed that CRT improved the immunological characteristics of unresectable locally advanced ESCC and identified the density of PD-1+CD8+ T cells as a predictive factor for prognosis. This finding supports the rationale for the necessity of subsequent PD-1 inhibitor treatment.

Tumor-intrinsic IFNα and CXCL10 are critical for immunotherapeutic efficacy by recruiting and activating T lymphocytes in tumor microenvironment

Tumor immunotherapies targeting PD-(L)1 exhibit anti-tumor efficacy in only 10-30% of patients with various cancers. Literature has demonstrated that a "hot tumor" which contains high T lymphocytes in the tumor microenvironment exhibits a better response to immunotherapies than a "cold tumor." This study aimed to investigate whether tumor-intrinsic IFNα and CXCL10 determine the recruitment and activation of CD8+ T cells to become "hot tumor." In this study, we found that CXCL10 overexpressed in a variety of tumors including lung, colon, and liver tumors with a correlation with PD-L1. High PD-L1 and CXCL10 are associated with better survival rates in tumor patients receiving immunotherapies. IFNs-downstream transcriptional factor IRF-1 and STAT1 were correlated with PD-L1 and CXCL10 expression. We demonstrated that IRF-1 and STAT1 were both bound with the promoters of PD-L1 and CXCL10, sharing the same signaling pathway and determining IFNs-mediated PD-L1 and CXCL10 expression. In addition, IFNα significantly increased activation marker IFNγ in PBMCs, promoting M1 type monocyte differentiation, CD4+ T, and CD8+ T cell activation. Particularly, we found that CD8+ T lymphocytes abundantly expressed CXCR3, a receptor of CXCL10, by flow cytometry, indicating that tumor-intrinsic CXCL10 potentially recruited CD8+ T in tumor microenvironment. To demonstrate the hypothesis, immunotherapy-sensitive CT26 and immunotherapy-resistant LL/2 were used and we found that CT26 cells exhibited higher IFNα, IFNγ, CXCL10, and PD-L1 levels compared to LL/2, leading to higher IFNγ expression in mouse splenocytes. Moreover, we found that CD8+ T cells were recruited by CXCL10 in vitro, whereas SCH546738, an inhibitor of CXCR3, inhibited T cell migration and splenocytes-mediated anti-tumor effect. We then confirmed that CT26-derived tumor was sensitive to αPD-L1 immunotherapy and LL/2-tumor was resistant, whereas αPD-L1 significantly increased T lymphocyte activation marker CD107a in CT26-derived BALB/c mice. In conclusion, this study revealed that CXCL10 expression is correlated with PD-L1 in tumors, sharing the same signaling pathway and associating with better immunotherapeutic efficacy. Further evidence in the syngeneic tumor models demonstrated that immunotherapy-sensitive CT26 intrinsically exhibited higher IFNα and CXCL10 compared to immunotherapy-resistant LL/2 to recruit and activate CD8+ T cells in the tumor microenvironment, exhibiting "hot tumor" characteristic of sensitizing αPD-L1 immunotherapies.

A good response to anti-PD-1 monoclonal antibody plus SBRT in a patient with PD-L1-negative recurrent advanced esophageal cancer: a long-term follow-up case report of a possible abscopal effect

There are limited treatment options for recurrent advanced esophageal squamous cell carcinoma. A good response with a possible abscopal effect was observed in a patient with programmed death-ligand 1 (PD-L1)-negative recurrent advanced esophageal squamous cell carcinoma treated with an anti-PD-1 monoclonal antibody plus stereotactic body radiotherapy (SBRT). A 66-year-old male patient was diagnosed with recurrent advanced esophageal squamous cell carcinoma with multiple lung metastases (13 metastatic nodules in total) four months after completing radical radiotherapy plus concurrent and consolidated chemotherapy, and PD-L1 expression in the primary esophageal tumor was negative. This patient received 25 cycles of camrelizumab (an anti-PD-1 monoclonal antibody) in total plus upfront SBRT for two metastatic nodules, which was administered after the first cycle of camrelizumab. After this combined treatment, for most nontarget nodules, an obvious volume decrease and fuzzy change were observed, including two nodules that completely vanished. At the end of follow-up, the progression-free survival and duration of response of this patient were 34 months and 32 months, respectively. This case report indicated that an anti-PD-1 monoclonal antibody combined with SBRT was a promising therapeutic strategy for recurrent esophageal squamous cell carcinoma even in patients with negative PD-L1 expression.

Double-dose osimertinib combined with intrathecal injection of pemetrexed improves the efficacy of EGFR-mutant non-small cell lung cancer and leptomeningeal metastasis: case report and literature review

Leptomeningeal metastasis (LM) is a complication of non-small cell lung cancer (NSCLC) characterized by poor prognosis and short survival. A variety of therapeutic approaches have been sought to improve the efficacy of LM. Here we present a clinical case and conduct a literature review to investigate the effectiveness and safety of double-dose osimertinib combined with a pemetrexed intrathecal injection. This is an older man who underwent thoracoscopic pneumonectomy and was diagnosed with stage IIA lung adenocarcinoma with EGFR21 L858R mutation. He experienced thoracic vertebral metastases 33 months postoperatively and received first-line treatment with gefitinib combined with radiotherapy for vertebral metastases. However, the patient developed a grade 3 rash with unacceptable toxicity and his CEA levels were significantly increased 22 months later, leading to a targeted treatment adjustment to 80 mg of osimertinib orally once daily. Four months later, the patient developed LM and osimertinib dosage was increased to 160 mg once daily; however, neurological symptoms did not improve, and cerebrospinal fluid (CSF) tumor cells remained detected. Accordingly, the patient received an intrathecal injection of pemetrexed (dose 30 mg) every 2-3 months, 2-3 times per course (4-6 days each time), and continued to receive a double dose of osimertinib. After three courses of intrathecal chemotherapy, CSF tumor cells were eliminated, and neurological symptoms significantly improved. During the treatment, he experienced a one-degree rash, leukopenia, thrombocytopenia, and fatigue. This patient has been alive and well with disease control for 28 months since the diagnosis of meningeal metastases. Combining double-dose osimertinib and an intrathecal injection of pemetrexed demonstrated therapeutic efficacy and manageable adverse effects in this patient with advanced NSCLC with EGFR-mutant and LM.

The role of radiotherapy in tumor immunity and the potential of PET/CT in detecting the expression of PD-1/PD-L1

Upregulation of PD-1/PD-L1 allows cancer cells to escape from host immune systems by functionally inactivating T-cell immune surveillance. Clinical blockade strategies have resulted in an increased prevalence of patients with late-stage cancers. However, many cancer patients had limited or no response to current immunotherapeutic strategies. Therefore, how to improve the sensitivity of immunotherapy has become the focus of attention of many scholars. Radiotherapy plays a role in the recruitment of T cells in the tumor microenvironment, increases CD4 + and CD8 + T cells, and increases PD-L1 expression, resulting in the synergistically enhanced antitumor effect of irradiation and PD-L1 blockade. Radiotherapy can cause changes in tumor metabolism, especially glucose metabolism. Tumor glycolysis and tumor immune evasion are interdependent, glycolytic activity enhances PD-L1 expression on tumor cells and thus promotes anti-PD-L1 immunotherapy response. Therefore, the mechanism of radiotherapy affecting tumor immunity may be partly through intervention of tumor glucose metabolism. Furthermore, some authors had found that the uptake of 2'-deoxy-2'-[18F]fluoro-D-glucose(18F-FDG) was correlated with PD-1/PD-L1 expression. Positron emission tomography/computed tomography (PET/CT) is a non-invasive detection method for PD-1/PD-L1 expression and has several potential advantages over immunohistochemical (IHC), PET/CT can dynamically reflect the expression of PD-1/PD-L1 inside the tumor and further guide clinical treatment.

Global research landscape and trends of cancer radiotherapy plus immunotherapy: A bibliometric analysis

The aim of this study was to present current research trends on the synergistic use of radiotherapy and immunotherapy (IRT) for cancer treatment. On March 1, 2023, we conducted a literature search for IRT papers using the Web of Science database. We extracted information and constructed two databases - the Core Database (CD) with 864 papers and Generalized Database (GD) with 6344 papers. A bibliometric analysis was performed to provide insights into the research landscape, to identify emerging trends and highly cited papers and journals in the field of IRT. The CD contained 864 papers that were collectively cited 31,818 times. Prominent journals in this area included the New England Journal of Medicine, Lancet Oncology, and the Journal of Clinical Oncology. Corresponding authors from the USA contributed the most publications. In recent years, lung cancer, melanoma, stereotactic radiotherapy, immune checkpoint inhibitors, and the tumor microenvironment emerged as hot research areas. This bibliometric analysis presented quantitative insights into research concerning IRT and proposed potential avenues for further exploration. Moreover, researchers can use our findings to select appropriate journals for publication or identify prospective collaborators. In summary, this bibliometric analysis provides a comprehensive overview of the historical progression and recent advancements in IRT research that may serve as inspiration for future investigations.

FGFR inhibition augments anti-PD-1 efficacy in murine FGFR3-mutant bladder cancer by abrogating immunosuppression

The combination of targeted therapy with immune checkpoint inhibition (ICI) is an area of intense interest. We studied the interaction of fibroblast growth factor receptor (FGFR) inhibition with ICI in urothelial carcinoma (UC) of the bladder, in which FGFR3 is altered in 50% of cases. Using an FGFR3-driven, Trp53-mutant genetically engineered murine model (UPFL), we demonstrate that UPFL tumors recapitulate the histology and molecular subtype of their FGFR3-altered human counterparts. Additionally, UPFL1 allografts exhibit hyperprogression to ICI associated with an expansion of T regulatory cells (Tregs). Erdafitinib blocked Treg proliferation in vitro, while in vivo ICI-induced Treg expansion was fully abrogated by FGFR inhibition. Combined erdafitinib and ICI resulted in high therapeutic efficacy. In aggregate, our work establishes that, in mice, co-alteration of FGFR3 and Trp53 results in high-grade, non-muscle-invasive UC and presents a previously underappreciated role for FGFR inhibition in blocking ICI-induced Treg expansion.

Novel dual inhibitors of PARP and HDAC induce intratumoral STING-mediated antitumor immunity in triple-negative breast cancer

PARP inhibitors and HDAC inhibitors have been approved for the clinical treatment of malignancies, but acquired resistance of or limited effects on solid tumors with a single agent remain as challenges. Bioinformatics analyses and a combination of experiments had demonstrated the synergistic effects of PARP and HDAC inhibitors in triple-negative breast cancer. A series of novel dual PARP and HDAC inhibitors were rationally designed and synthesized, and these molecules exhibited high enzyme inhibition activity with excellent antitumor effects in vitro and in vivo. Mechanistically, dual PARP and HDAC inhibitors induced BRCAness to restore synthetic lethality and promoted cytosolic DNA accumulation, which further activates the cGAS-STING pathway and produces proinflammatory chemokines through type I IFN-mediated JAK-STAT pathway. Moreover, these inhibitors promoted neoantigen generation, upregulated antigen presentation genes and PD-L1, and enhanced antitumor immunity when combined with immune checkpoint blockade therapy. These results indicated that novel dual PARP and HDAC inhibitors have antitumor immunomodulatory functions in triple-negative breast cancer. Novel dual PARP and HDAC inhibitors induce BRCAness to restore synthetic lethality, activating tumoral IFN signaling via the cGAS-STING pathway and inducing cytokine production, promoting neoantigen generation and presentation to enhance the immune response.

Combining spatially fractionated radiation therapy (SFRT) and immunotherapy opens new rays of hope for enhancing therapeutic ratio

Spatially Fractionated Radiation Therapy (SFRT) is a form of radiotherapy that delivers a single large dose of radiation within the target volume in a heterogeneous pattern with regions of peak dosage and regions of under dosage. SFRT types can be defined by how the heterogeneous pattern of radiation is obtained. Immune checkpoint inhibitors (ICIs) have been approved for various malignant tumors and are widely used to treat patients with metastatic cancer. The efficacy of ICI monotherapy is limited due to the "cold" tumor microenvironment. Fractionated radiotherapy can achieve higher doses per fraction to the target tumor, and induce immune activation (immodulate tumor immunogenicity and microenvironment). Therefore, coupling ICI therapy and fractionated radiation therapy could significantly improve the outcome of metastatic cancer. This review focuses on both preclinical and clinical studies that use a combination of radiotherapy and ICI therapy in cancer.

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.

Safety and efficacy of thoracic radiotherapy combined with chemo-immunotherapy in patients with extensive-stage small cell lung cancer: a multicenter retrospective analysis

Background

Immunotherapy has greatly increased the survival time of patients with extensive-stage small cell lung cancer (ES-SCLC), and is now a standard first-line treatment for these patients. Increasing evidence suggests a possible synergistic effect between immunotherapy and radiotherapy, yet there is a paucity of evidence regarding the efficacy and safety of thoracic radiotherapy (TRT) combined with chemo-immunotherapy for ES-SCLC.

Methods

The medical records of 78 consecutive patients with ES-SCLC who received TRT in combination with chemo-immunotherapy at Jinling Hospital and Jiangsu Cancer Hospital from January 2019 to January 2023 were retrospectively reviewed. The median overall survival (mOS) time and median progression-free survival (mPFS) time were used to evaluate efficacy, and the incidence of adverse events (AEs) was used to evaluate safety.

Results

The median follow-up time was 31.9 months, the objective response rate (ORR) was 59%, and the disease control rate (DCR) was 89.8%. The mOS time was 20.0 months, and the 6-month OS rate was 95%. The mPFS time was 9.2 months, and the 6-month PFS rate was 78%. There were no treatment-related deaths. The incidence of pneumonitis was 23.1%, the incidence of radiation esophagitis was 5.1%, and 2 patients experienced high-grade pneumonitis. Primary liver metastasis was a predictor of poor OS and PFS. Patients who received consolidative TRT after chemo-immunotherapy experienced more benefit than those who received TRT as palliative or salvage treatment for superior vena cava syndrome or disease progression.

Conclusions

TRT is a feasible treatment for patients who receive chemo-immunotherapy for the management of ES-SCLC in consideration of its considerable efficacy and tolerable safety risk. This treatment is especially useful for patients without primary liver metastasis and who receive consolidative TRT after chemo-immunotherapy. Large-scale prospective studies are needed to confirm the efficacy and safety of this treatment modality.

IMP3 Immunohistochemical Expression Is Related with Progression and Metastases in Xenografted and Cutaneous Melanomas

INTRODUCTION

Insulin-like growth factor-II messenger RNA-binding protein-3 (IMP3) over-expression is a predictor of tumor recurrence and metastases in some types of human melanoma. Our objective was to evaluate the immunohistochemical expression of IMP3 and other molecules related to tumor prognosis in melanoma-xeno-tumors undergoing treatment. We test the effect of radiotherapy (RT) and mesenchymal stromal cells (MSCs) treatment, analyzing the tumorigenic and metastatsizing capacity in a mice melanoma xenograft model.

MATERIALS AND METHODS

We inoculated A375 and G361 human melanoma cell lines into NOD/SCID gamma mice (n = 64). We established a control group, a group treated with MSCs, a group treated with MSCs plus RT, and a group treated with RT. We assessed the immunohistochemical expression of IMP3, E-cadherin, N-cadherin, PARP1, HIF-1α, and the proliferation marker Ki-67. Additionally, we performed a retrospective study including 114 histological samples of patients diagnosed with malignant cutaneous superficial spreading melanoma (n = 104) and nodular melanoma (n = 10) with at least 5 years of follow-up.

RESULTS

Most morphological and immunohistochemical features show statistically significant differences between the 2 cell lines. The A375 cell line induced the formation of metastases, while the G361 cell line provoked tumor formation but not metastases. All three treatments reduced the cell proliferation evaluated by the Ki-67 nuclear antigen (p = 0.000, one-way ANOVA test) and reduced the number of metastases (p = 0.004, one-way ANOVA test). In addition, the tumor volumes reduced in comparison with the control groups, 31.74% for RT + MSCs in the A357 tumor cell line, and 89.84% RT + MSCs in the G361 tumor cell line. We also found that IMP3 expression is associated with greater tumor aggressiveness and was significantly correlated with cell proliferation (measured by the expression of Ki-67), the number of metastases, and reduced expression of adhesion molecules.

CONCLUSIONS

The combined treatment of RT and MSCs on xenografted melanomas reduces tumor size, metastases frequency, and the epithelial to mesenchymal transition/PARP1 metastatic phenotype. This treatment also reduces the expression of molecules related to cellular proliferation (Ki-67), molecules that facilitate the metastatic process (E-cadherin), and molecules related with prognosis (IMP3).

Ultra-high dose-rate proton FLASH improves tumor control

BACKGROUND AND PURPOSE

Proton radiotherapy (PRT) offers potential benefits over other radiation modalities, including photon and electron radiotherapy. Increasing the rate at which proton radiation is delivered may provide a therapeutic advantage. Here, we compared the efficacy of conventional proton therapy (CONVpr) to ultrahigh dose-rate proton therapy, FLASHpr, in a mouse model of non-small cell lung cancers (NSCLC).

MATERIALS AND METHODS

Mice bearing orthotopic lung tumors received thoracic radiation therapy using CONVpr (<0.05 Gy/s) and FLASHpr (>60 Gy/s) dose rates.

RESULTS

Compared to CONVpr, FLASHpr was more effective in reducing tumor burden and decreasing tumor cell proliferation. Furthermore, FLASHpr was more efficient in increasing the infiltration of cytotoxic CD8+ T-lymphocytes inside the tumor while simultaneously reducing the percentage of immunosuppressive regulatory T-cells (Tregs) among T-lymphocytes. Also, compared to CONVpr, FLASHpr was more effective in decreasing pro-tumorigenic M2-like macrophages in lung tumors, while increasing infiltration of anti-tumor M1-like macrophages. Finally, FLASHpr treatment reduced expression of checkpoint inhibitors in lung tumors, indicating reduced immune tolerance.

CONCLUSIONS

Our results suggest that FLASH dose-rate proton delivery modulates the immune system to improve tumor control and might thus be a promising new alternative to conventional dose rates for NSCLC treatment.

Ablative radiotherapy improves survival but does not cure autochthonous mouse models of prostate and colorectal cancer

BACKGROUND

Genetically engineered mouse models (GEMMs) of cancer are powerful tools to study mechanisms of disease progression and therapy response, yet little is known about how these models respond to multimodality therapy used in patients. Radiation therapy (RT) is frequently used to treat localized cancers with curative intent, delay progression of oligometastases, and palliate symptoms of metastatic disease.

METHODS

Here we report the development, testing, and validation of a platform to immobilize and target tumors in mice with stereotactic ablative RT (SART). Xenograft and autochthonous tumor models were treated with hypofractionated ablative doses of radiotherapy.

RESULTS

We demonstrate that hypofractionated regimens used in clinical practice can be effectively delivered in mouse models. SART alters tumor stroma and the immune environment, improves survival in GEMMs of primary prostate and colorectal cancer, and synergizes with androgen deprivation in prostate cancer. Complete pathologic responses were achieved in xenograft models, but not in GEMMs.

CONCLUSIONS

While SART is capable of fully ablating xenografts, it is unable to completely eradicate disease in GEMMs, arguing that resistance to potentially curative therapy can be modeled in GEMMs.

Neoadjuvant treatment does not influence PD-L1 expression in stage III non-small-cell lung cancer: a retrospective analysis of tumor samples from the trials SAKK 16/96, 16/00, 16/01, and 16/14

BACKGROUND

The inclusion of immune checkpoint inhibitors (ICIs) in the treatment of operable stage III non-small-cell lung cancer is becoming a new standard. Programmed death-ligand 1 (PD-L1) protein expression on tumor cells has emerged as the most important biomarker for sensitivity to ICIs targeting the programmed cell death protein 1 (PD-1)-PD-L1 axis. Little is known about the impact of neoadjuvant treatment on PD-L1 expression.

PATIENTS AND METHODS

We assessed PD-L1 expression by immunohistochemistry (Ventana SP263 assay) on tumor cells in treatment-naive diagnostic tumor samples and matched lung resections from patients with stage III non-small-cell lung cancer included in the Swiss Group for Clinical Cancer Research (SAKK) trials 16/96, 16/00, 16/01, and 16/14. All patients received neoadjuvant chemotherapy (CT) with cisplatin/docetaxel, either as single modality (CT), with sequential radiotherapy [chemoradiation therapy (CRT)] or with the PD-L1 inhibitor durvalumab (CT + ICI).

RESULTS

Overall, 132 paired tumor samples were analyzed from patients with neoadjuvant CT (n = 69), CRT (n = 33) and CT + ICI (n = 30). For CT and CRT, PD-L1 expression before and after neoadjuvant treatment did not differ significantly (Wilcoxon test, P = 0.94). Likewise, no statistically significant difference was observed between CT and CRT for PD-L1 expression after neoadjuvant treatment (P = 0.97). For CT + ICI, PD-L1 expression before and after neoadjuvant treatment also did not differ significantly (Wilcoxon test, P > 0.99). Event-free survival and overall survival for patients with downregulation or upregulation of PD-L1 expression after neoadjuvant treatment were similar.

CONCLUSIONS

In our cohort of patients neoadjuvant treatment did not influence PD-L1 expression, irrespective of the specific neoadjuvant treatment protocol. Dynamic change of PD-L1 expression did not correlate with event-free survival or overall survival.

Non-POU Domain-Containing Octomer-Binding (NONO) protein expression and stability promotes the tumorigenicity and activation of Akt/MAPK/β-catenin pathways in human breast cancer cells

Breast cancer is one of the most common cancers with a high mortality rate, underscoring the need to identify new therapeutic targets. Here we report that non-POU domain-containing octamer-binding (NONO) protein is overexpressed in breast cancer and validated the interaction of the WW domain of PIN1 with c-terminal threonine-proline (thr-pro) motifs of NONO. The interaction of NONO with PIN1 increases the stability of NONO by inhibiting its proteasomal degradation, and this identifies PIN1 as a positive regulator of NONO in promoting breast tumor development. Functionally, silencing of NONO inhibits the growth, survival, migration, invasion, epithelial to mesenchymal transition (EMT), and stemness of breast cancer cells in vitro. A human metastatic breast cancer cell xenograft was established in transparent zebrafish (Danio rerio) embryos to study the metastatic inability of NONO-silenced breast cancer cells in vivo. Mechanistically, NONO depletion promotes the expression of the PDL1 cell-surface protein in breast cancer cells. The identification of novel interactions of NONO with c-Jun and β-catenin proteins and activation of the Akt/MAPK/β-catenin signaling suggests that NONO is a novel regulator of Akt/MAPK/β-catenin signaling pathways. Taken together, our results indicated an essential role of NONO in the tumorigenicity of breast cancer and could be a potential target for anti-cancerous drugs. Video Abstract.

Mechanistic rationales for combining immunotherapy with radiotherapy

Immunotherapy consisted mainly of immune checkpoint inhibitors (ICIs) has led to significantly improved antitumor response. However, such response has been observed only in tumors possessing an overall responsive tumor immune micro-environment (TIME), in which the presence of functional tumor-infiltrating lymphocytes (TILs) is critical. Various mechanisms of immune escape from immunosurveillance exist, leading to different TIME phenotypes in correlation with primary or acquired resistance to ICIs. Radiotherapy has been shown to induce antitumor immunity not only in the irradiated primary tumor, but also at unirradiated distant sites of metastases. Such antitumor immunity is mainly elicited by radiation's stimulatory effects on antigenicity and adjuvanticity. Furthermore, it may be significantly augmented when irradiation is combined with immunotherapy, such as ICIs. Therefore, radiotherapy represents one potential therapeutic strategy to restore anti-tumor immunity in tumors presenting with an unresponsive TIME. In this review, the generation of anti-tumor immunity, its impairment, radiation's immunogenic properties, and the antitumor effects of combining radiation with immunotherapy will be comprehensively discussed.

Conserved transcriptional connectivity of regulatory T cells in the tumor microenvironment informs new combination cancer therapy strategies

While regulatory T (Treg) cells are traditionally viewed as professional suppressors of antigen presenting cells and effector T cells in both autoimmunity and cancer, recent findings of distinct Treg cell functions in tissue maintenance suggest that their regulatory purview extends to a wider range of cells and is broader than previously assumed. To elucidate tumoral Treg cell 'connectivity' to diverse tumor-supporting accessory cell types, we explored immediate early changes in their single-cell transcriptomes upon punctual Treg cell depletion in experimental lung cancer and injury-induced inflammation. Before any notable T cell activation and inflammation, fibroblasts, endothelial and myeloid cells exhibited pronounced changes in their gene expression in both cancer and injury settings. Factor analysis revealed shared Treg cell-dependent gene programs, foremost, prominent upregulation of VEGF and CCR2 signaling-related genes upon Treg cell deprivation in either setting, as well as in Treg cell-poor versus Treg cell-rich human lung adenocarcinomas. Accordingly, punctual Treg cell depletion combined with short-term VEGF blockade showed markedly improved control of PD-1 blockade-resistant lung adenocarcinoma progression in mice compared to the corresponding monotherapies, highlighting a promising factor-based querying approach to elucidating new rational combination treatments of solid organ cancers.

Radiotherapy combined with anti-CEACAM1 immunotherapy to induce survival advantage in glioma

BACKGROUND

We aimed to observe the effect of radiotherapy on the expression of immune checkpoint molecule CEACAM1 in patients with glioma and the therapeutical effect of radiotherapy combined with blockade of CEACAM1 in mice with intracranial gliomas.

METHODS

The expression of CEACAM1 on T-lymphocytes in the peripheral blood of patients with glioma was detected before and after radiotherapy; GL261 murine glioma cells (stably transfected with the luciferase gene) were implanted in the right caudate nucleus of C57BL/6 mice, and tumour growth was observed using the small animal in vivo imaging system. Mice were divided into 4 groups: (1) the isotype control; (2) the radiotherapy; (3) the anti-CEACAM1 treatment; and (4) the combination therapy. The survival of mice after treatment was recorded; the expression of CEACAM1 on murine glioma cells was detected by immunohistochemistry before and after radiotherapy; flow cytometry was adopted to detect CD8⁺ T-cells (Treg) (CD4⁺FoxP3⁺CD25⁺) among mouse brain-infiltrating T-cells; serum levels of IFN-γ and IL-10 were detected by ELISA; proliferation and apoptosis were observed by immunohistochemistry; Retrospective RNA-seq data analysis was conducted in a cohort of 325 patients with glioma in the Chinese Glioma Genome Atlas (CGGA) database and 702 patients in The Cancer Genome Atlas (TCGA) database.

RESULTS

The expression of CEACAM1 on CD4⁺ and CD8⁺ T-cells in the peripheral blood of patients with glioma was significantly higher 1 week after radiotherapy than before radiotherapy and was further increased 1 month after radiotherapy. Combined therapy notably inhibited the growth of intracranial tumours in mice and prolonged their survival time, with some mice being capable of surviving long-term (> 90 d). Immunohistochemistry revealed that the expression of CEACAM1 in murine glioma tissues after radiotherapy was elevated in a time-dependent manner. Flow cytometry analysis showed an increase in mouse brain-infiltrating CD8⁺ T-lymphocytes, a decrease in Treg cells, and an increase in CD8⁺ T/Treg cells after treatment. ELISA demonstrated the elevated levels of IFN and decreased levels of IL-10 in the serum of mice in the combination therapy group.

CONCLUSIONS

Radiotherapy combined with CEACAM1 inhibitors resulted in strong and durable anti-tumour immune responses against murine glioma and long-term survival of some mice. Hence, this study is expected to offer new effective immunotherapy strategies against glioma.

Posttranslational regulation of liver kinase B1 (LKB1) in human cancer

Liver kinase B1 (LKB1) is a serine-threonine kinase that participates in multiple cellular and biological processes, including energy metabolism, cell polarity, cell proliferation, cell migration, and many others. LKB1 is initially identified as a germline-mutated causative gene in Peutz-Jeghers syndrome (PJS) and is commonly regarded as a tumor suppressor due to frequent inactivation in a variety of cancers. LKB1 directly binds and activates its downstream kinases including the AMP-activated protein kinase (AMPK) and AMPK-related kinases by phosphorylation, which has been intensively investigated for the past decades. An increasing number of studies has uncovered the posttranslational modifications (PTMs) of LKB1 and consequent changes in its localization, activity, and interaction with substrates. The alteration in LKB1 function as a consequence of genetic mutations and aberrant upstream signaling regulation leads to tumor development and progression. Here, we review current knowledge about the mechanism of LKB1 in cancer and the contributions of PTMs, such as phosphorylation, ubiquitination, SUMOylation, acetylation, prenylation, and others, to the regulation of LKB1 function, offering new insights into the therapeutic strategies in cancer.

Prognostic impact of PD-L1 and TIGIT expression in non-small cell lung cancer following concurrent chemo-radiotherapy

We investigated the effect of preoperative therapy for non-small cell lung cancer on programmed death-ligand 1 (PD-L1), programmed death-1 (PD-1), poliovirus receptor (CD155), and T cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif (ITIM) domain (TIGIT) expression and prognosis with the cases of 28 patients received preoperative concurrent chemo-radiotherapy (cCRT) and 27 received preoperative drug therapy. The post-treatment PD-L1 expression was higher in cCRT group than in the drug therapy (50.0% vs 5.0%, p = 0.000), whereas that of CD155 did not significantly differ (40.0% vs 60.0%, p = 0.131). The PD-1 expression was not significantly different between the cCRT and drug therapy groups (51.1% vs 42.9%, p = 0.076), while the TIGIT was significantly higher in the cCRT group (41.5% vs 34.0%, p = 0.008). The patients who received cCRT resulted in elevated PD-L1and TIGIT values had a worse prognosis (p = 0.008). The PD-L1 and TIGIT expression after cCRT was significantly higher than after drug treatment. The cCRT population with high expression of both had a significantly poorer prognosis, indicating elevation of PD-L1 and TIGIT after cCRT as a negative prognostic factor. Combination therapy with anti-PD-L1 and anti-TIGIT antibodies after cCRT may contribute to an improved prognosis.

Inhibition of autophagy and MEK promotes ferroptosis in Lkb1-deficient Kras-driven lung tumors

LKB1 and KRAS are the third most frequent co-mutations detected in non-small cell lung cancer (NSCLC) and cause aggressive tumor growth. Unfortunately, treatment with RAS-RAF-MEK-ERK pathway inhibitors has minimal therapeutic efficacy in LKB1-mutant KRAS-driven NSCLC. Autophagy, an intracellular nutrient scavenging pathway, compensates for Lkb1 loss to support Kras-driven lung tumor growth. Here we preclinically evaluate the possibility of autophagy inhibition together with MEK inhibition as a treatment for Kras-driven lung tumors. We found that the combination of the autophagy inhibitor hydroxychloroquine (HCQ) and the MEK inhibitor Trametinib displays synergistic anti-proliferative activity in KrasG12D/+;Lkb1-/- (KL) lung cancer cells, but not in KrasG12D/+;p53-/- (KP) lung cancer cells. In vivo studies using tumor allografts, genetically engineered mouse models (GEMMs) and patient-derived xenografts (PDXs) showed anti-tumor activity of the combination of HCQ and Trametinib on KL but not KP tumors. We further found that the combination treatment significantly reduced mitochondrial membrane potential, basal respiration, and ATP production, while also increasing lipid peroxidation, indicative of ferroptosis, in KL tumor-derived cell lines (TDCLs) and KL tumors compared to treatment with single agents. Moreover, the reduced tumor growth by the combination treatment was rescued by ferroptosis inhibitor. Taken together, we demonstrate that autophagy upregulation in KL tumors causes resistance to Trametinib by inhibiting ferroptosis. Therefore, a combination of autophagy and MEK inhibition could be a novel therapeutic strategy to specifically treat NSCLC bearing co-mutations of LKB1 and KRAS.

Influence of chemoradiation on the immune microenvironment of cervical cancer patients

PURPOSE

Cervical cancer remains a leading cause of cancer death in women. While immunotherapy has shown great success in combating cancer, the value of immunotherapy in cervical cancer is still only beginning to be explored. Thus, we performed a prospective analysis of patient blood and tumor samples at the beginning and end of conventional chemoradiation to assess changes in the immune cell and immunoreceptor compartments, and investigate if and when the addition of immunotherapy could be beneficial.

METHODS

Patients with FIGO II-III cervical cancer receiving standard chemoradiation between January 2020 and December 2021 were included. We collected tumor and blood samples from patients before and at the end of therapy and analyzed immune cell composition and immune checkpoint receptor expression on both immune and tumor cells using multicolor flow cytometry.

RESULTS

In all, 34 patients were eligible in the study period; 22 could be included and analyzed in this study. We found that chemoradiation significantly reduces T cell numbers in both tumors and blood, but increases macrophage and neutrophil numbers in tumors. Furthermore, we found that the percentage of immune checkpoint receptor PD‑1 and TIGIT-expressing cells in tumors was significantly reduced at the end of therapy and that CD4 and CD8 memory T cell populations were altered by chemoradiation. In addition, we observed that while PD-L1 expression intensity was upregulated by chemoradiation on blood CD8 cells, PD-L1 expression frequency and the expression intensity of antigen-presenting molecule MHC‑I were significantly reduced on tumor cells.

CONCLUSION

Our data demonstrate that chemoradiation significantly alters the immune cell composition of human cervical tumors and the expression of immune checkpoint receptors on both lymphocytes and tumor cells. As our results reveal that the percentage of PD‑1⁺ CD8 cells in the tumor as well as the frequency of PD-L1-expressing tumor cells were reduced at the end of therapy, neoadjuvant or simultaneous anti-PD‑1 or anti-PD-L1 treatment might provide better treatment efficiency in upcoming clinical studies.

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.

PD-L1: Biological mechanism, function, and immunotherapy in gastric cancer

Gastric cancer (GC) is one of the main causes of cancer incidence rate and mortality worldwide. As the main breakthrough direction, the application of immune checkpoint inhibitors makes patients with GC have better prognosis, where PD-L1/PD-1 inhibitors in immunotherapy have good anti-tumor immune efficacy. Further understanding of the regulatory mechanism of PD-L1 in GC may bring substantial progress to the immunotherapy. In this review, we provide information on the endogenous and exogenous regulatory mechanisms of PD-L1 and its biological functions combined with current clinical trials of PD-L1/PD-1 inhibitors in GC. The malignant biological phenotypes caused by PD-L1 and the corresponding clinical combined treatment scheme have been reported. Identifying the biomarkers of the potential efficacy of immunotherapy and specifying the clinical immunotherapy scheme in combination with molecular characteristics of patients may maximize clinical benefits and better prognosis.

Comparing the Therapeutic Efficacies of Lung Cancer: Network Meta-Analysis Approaches

BACKGROUND

In recent years, reduction of nuclear power generation and the use of coal-fired power for filling the power supply gap might have increased the risk of lung cancer. This study aims to explore the most effective treatment for different stages of lung cancer patients.

METHODS

We searched databases to investigate the treatment efficacy of lung cancer. The network meta-analysis was used to explore the top three effective therapeutic strategies among all collected treatment methodologies.

RESULTS

A total of 124 studies were collected from 115 articles with 171,757 participants in total. The results of network meta-analyses showed that the best top three treatments: (1) in response rate, for advanced lung cancer were Targeted + Targeted, Chemo + Immuno, and Targeted + Other Therapy with cumulative probabilities 82.9, 80.8, and 69.3%, respectively; for non-advanced lung cancer were Chemoradio + Targeted, Chemoradi + Immuno, and Chemoradio + Other Therapy with cumulative probabilities 69.0, 67.8, and 60.7%, respectively; (2) in disease-free control rate, for advanced lung cancer were Targeted + Others, Chemo + Immuno, and Targeted + Targeted Therapy with cumulative probabilities 93.4, 91.5, and 59.4%, respectively; for non-advanced lung cancer were Chemo + Surgery, Chemoradio + Targeted, and Surgery Therapy with cumulative probabilities 80.1, 71.5, and 43.1%, respectively.

CONCLUSION

The therapeutic strategies with the best effectiveness will be different depending on the stage of lung cancer patients.

Fibrocytes boost tumor-supportive phenotypic switches in the lung cancer niche via the endothelin system

Fibrocytes are bone marrow-derived monocytic cells implicated in wound healing. Here, we identify their role in lung cancer progression/ metastasis. Selective manipulation of fibrocytes in mouse lung tumor models documents the central role of fibrocytes in boosting niche features and enhancing metastasis. Importantly, lung cancer patients show increased number of circulating fibrocytes and marked fibrocyte accumulation in the cancer niche. Using double and triple co-culture systems with human lung cancer cells, fibrocytes, macrophages and endothelial cells, we substantiate the central features of cancer-supporting niche: enhanced cancer cell proliferation and migration, macrophage activation, augmented endothelial cell sprouting and fibrocyte maturation. Upregulation of endothelin and its receptors are noted, and dual endothelin receptor blockade suppresses all cancer-supportive phenotypic alterations via acting on fibrocyte interaction with the cancer niche. We thus provide evidence for a crucial role of fibrocytes in lung cancer progression and metastasis, suggesting targets for treatment strategies.

Radiotherapy combined with PD-1/PD-L1 inhibitors in NSCLC brain metastases treatment: The mechanisms, advances, opportunities, and challenges

At present, whole-brain radiation therapy/stereotactic radiosurgery is one of the main local treatments for brain metastasis of non-small-cell lung cancer (NSCLC). Currently, it has been proved that radiotherapy (RT) can regulate the immune response, and small-sample studies have shown that patients with NSCLC brain metastases (BMs) can benefit from RT combined with immunotherapy (IO). However, the efficacy and safety of the combination treatment have not been deeply elaborated. Notably, as a challenge that is still being explored, the timing of RT combined with IO is likely to be an important factor affecting efficacy and prognosis. This article reviews the current application and challenges of RT combined with IO from the perspectives of molecular mechanism, combination timing, safety, and efficacy. The purpose is to provide information on clinical evidence-based medicine of combination between RT with IO. For further investigation, we also discuss the major challenges and prospects of RT combined with IO in NSCLC BMs.

PD-1 blockade synergizes with oxaliplatin-based, but not cisplatin-based, chemotherapy of gastric cancer

Preclinical experimentation revealed that established cancers treated with the immunogenic cell death (ICD) inducer oxaliplatin are sensitized to immune checkpoint inhibitors targeting PD-1. In contrast, no such sensitizing effect is observed when cisplatin, a non-immunogenic cell death inducer is used. Two randomized phase III clinical trials targeting unresectable gastric and gastro-esophageal junction carcinomas apparently validate this observation. Thus, oxaliplatin-based chemotherapy (together with capecitabine or 5-fluorouracil plus leucovorin) favorably interacted with nivolumab, yielding improved outcome. In contrast, the outcome of cisplatin-based chemotherapy (together with capecitabine or 5-fluorouracil) failed to be improved by concomitant treatment with pembrolizumab. These clinical findings underscore the importance of choosing appropriate ICD-inducing cytotoxicants for the development of chemoimmunotherapeutic regimens. Unfortunately, the FDA and EMA have approved PD-1 blockade in combination with “platinum-based chemotherapy” without specifying the precise nature of the platinum-containing drug. This is a non sequitur. Based on the available clinical data, such approvals should be restricted to the use of oxaliplatin.

Impact of Previous Local Treatment for Brain Metastases on Response to Molecular Targeted Therapy in BRAF-Mutant Melanoma Brain Metastasis: A Systematic Review and Meta-Analysis

Background

Melanoma brain metastases (BMs) are associated with poor prognosis and are the main cause of mortality in melanoma patients. BRAF inhibitors have shown intracranial activity in both treatment-naïve and previously treated BM patients. We aimed to investigate if there was any difference in response of BRAF inhibitors in these two cohorts.

Materials and Methods

Electronic database search included PubMed, Medline, and Cochrane library until March 2021 for studies with desired comparative outcomes. Outcomes of interest that were obtained for meta-analysis included intracranial response rate as the primary outcome and survival and safety outcomes as the secondary outcomes. Review Manager version 5.4 was used for data analysis.

Results

Three studies comprising 410 BRAF-mutated melanoma patients with BMs were included according to eligibility criteria. The comparative cohort included patients with treatment-naïve BMs (TN cohort; n = 255) and those who had progressive disease after receiving local brain treatment for BMs (PT cohort; n = 155). Meta-analysis revealed that BRAF inhibitors (vemurafenib and dabrafenib) and BRAF/MEK inhibitor combination (dabrafenib and trametinib) induced significantly higher intracranial disease control (OR 0.58 [95% CI: 0.34, 0.97], p = 0.04) and a trend toward improved progression-free survival (PFS) (HR 1.22 [95% CI: 0.98, 1.52], p = 0.08) in the PT cohort as compared to the TN cohort. Overall survival was not significantly different between the cohorts (HR 1.16 [95% CI: 0.89, 1.51], p = 0.28). Subgroup analysis revealed that PFS was significantly improved (HR 1.67 [95% CI: 1.06, 2.62], p = 0.03), and a trend toward improved OS (HR 1.62 [95% CI: 0.95, 2.75], p = 0.08) was achieved in patients receiving BRAF/MEK inhibitor combination and patients with BRAFv600K mutation receiving dabrafenib alone. No increase in overall adverse events (AEs), grade 3/4 AEs, and severe adverse events (SAEs) was observed between the cohorts.

Conclusions

BRAF inhibitors (plus MEK inhibitor) may achieve better intracranial disease stability in BRAF-mutant melanoma patients who have received previous local treatment for BMs.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/), identifier CRD42020185984.

The Long-Term and Short-Term Efficacy of Immunotherapy in Non-Small Cell Lung Cancer Patients With Brain Metastases: A Systematic Review and Meta-Analysis

BACKGROUND

Although immunotherapy has been widely used, there is currently no research comparing immunotherapy for non-small cell lung cancer (NSCLC) patients with brain metastases (BMs). This meta-analysis addresses a gap in the comparison of immunotherapy efficacy, including immune checkpoint inhibitors (ICIs), chemotherapy (CT), radiotherapy (RT), and ICI combined CT or RT.

METHODS

A search of Pubmed, Cochrane, EMBASE, and ClinicalTrial.gov was conducted to identify studies which enrolled NSCLC patients with BM treated with ICIs. The outcomes consisted of intracerebral overall response rate (iORR), intracerebral disease control rate (iDCR), extracranial overall response rate (EORR), distant brain failure (DBF), local control (LC), progression-free survival (PFS), and overall survival (OS).

RESULTS

A total of 3160 participants from 46 trials were included in the final analysis. Patients treated with immunotherapy were associated with a longer PFS (0.48, 95%CI: 0.41-0.56), and a longer OS (0.64, 95%CI: 0.60-0.69) compared with immunotherapy-naive patients. In prospective studies, dual ICI combined CT and ICI combined CT achieved a better OS. The hazard ratio (HR) of dual ICI combined CT versus dual ICI was 0.61, and the HR of ICI combined CT versus ICI monotherapy was 0.58. Moreover, no statistical difference in PFS, OS, EORR, iORR, iDCR, and EDCR was found between patients with ICI monotherapy and ICI combined cranial radiotherapy. Concurrent ICI combined RT was shown to decrease the rate of DBF (OR = 0.15, 95% CI: 0.03-0.73) compared with RT after ICI. Patients treated with WBRT might have an inferior efficacy than those with SRS because the iORR of SRS was 0.75 (0.70, 0.80) and WBRT was 0. Furthermore, no obvious difference in PFS and OS was observed among the three different types of ICI, which targets PD-1, PD-L1, and CTLA-4, respectively.

CONCLUSIONS

Patients treated with ICI got superior efficacy to those without ICI. Furthermore, dual ICI combined CT and ICI combined CT seemed to be optimal for NSCLC patients with BM. In terms of response and survival, concurrent administration of SRS and ICI led to better outcomes for patients with BMs than non-concurrent or non-SRS.

IMPORTANCE OF THE STUDY

In the new era of immunotherapy, our meta-analysis validated the importance of immunotherapy for non-small cell lung cancer (NSCLC) patients with brain metastases (BMs). By comparing the long-term and short-term impacts of various regimens, all immunotherapy treatments had superior efficacy to immunotherapy-naive. At the same time, through pairwise comparison in immunotherapy, our findings can help clinicians to make treatment decisions for NSCLC patients with BMs.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=269621, identifier CRD42021269621.

Immunotherapy in NSCLC Patients With Brain and Leptomeningeal Metastases

Immunotherapy has now been integrated as a treatment strategy for most patients with non-small cell lung cancer (NSCLC). However, the pivotal clinical trials that demonstrated its impressive efficacy often did not include patients with active, untreated brain metastases or leptomeningeal carcinomatosis. Nevertheless, NSCLC is the most common tumor to metastasize to the brain, and patients develop brain and meningeal involvement in approximately 40 and 10% of cases, respectively. Consequently, the appropriate care of these patients is a recurrent clinical concern. Although there are many aspects that would merit further investigation to explain the mechanism of intracranial response to immune checkpoint inhibitors (ICPs), some data suggest that they are able to cross the blood–brain barrier, resulting in local tumor microenvironment modification. This results in a similar clinical benefit in patients with stable, previously treated brain metastases compared to the general population. Despite important limitations, some real-life studies have described that the ICPs’ efficacy was maintained also in less selected patients with untreated or symptomatic brain metastases. In contrast, few data are available about patients with leptomeningeal carcinomatosis. Nevertheless, neurological complications due to ICP treatment in patients with brain metastases have to be evaluated and carefully monitored. Despite the fact that limited data are available in the literature, the purpose of this review is to show that the multimodal treatment of these patients with brain metastases and/or leptomeningeal disease should be discussed during tracing of the history of the disease, participating in the local and possibly systemic control of NSCLC.

How to Improve SBRT Outcomes in NSCLC: From Pre-Clinical Modeling to Successful Clinical Translation

Simple Summary

Despite major research and clinical efforts, lung cancer remains the leading cause of cancer-related death. Stereotactic body radiotherapy (SBRT) has emerged as a major treatment modality for lung cancer in the last decade. Additional research is needed to elucidate underlying mechanisms of resistance and to develop improved therapeutic strategies. Clinical progress relies on accurate preclinical modelling of human disease in order to yield clinically meaningful results; however, successful translation of pre-clinical research is still lagging behind. In this review, we summarize the major clinical developments of radiation therapy for non-small-cell lung cancer (NSCLC), and we discuss the pre-clinical research models at our disposal, highlighting ongoing translational challenges and future perspectives.

Abstract

Despite major research and clinical efforts, lung cancer remains the leading cause of cancer-related death. While the delivery of conformal radiotherapy and image guidance of stereotactic body radiotherapy (SBRT) have revolutionized the treatment of early-stage non-small-cell lung cancer (NSCLC), additional research is needed to elucidate underlying mechanisms of resistance and identify novel therapeutic combinations. Clinical progress relies on the successful translation of pre-clinical work, which so far has not always yielded expected results. Improved clinical modelling involves characterizing the preclinical models and selecting appropriate experimental designs that faithfully mimic precise clinical scenarios. Here, we review the current role of SBRT and the scope of pre-clinical armamentarium at our disposal to improve successful clinical translation of pre-clinical research in the radiation oncology of NSCLC.

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

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

The Research Progress of PD-1/PD-L1 Inhibitors Enhancing Radiotherapy Efficacy

Approximately 60%–70% of patients with malignant tumours require radiotherapy. The clinical application of immune checkpoint inhibitors (ICIs), such as anti-PD-1/PD-L1, has revolutionized cancer treatment and greatly improved the outcome of a variety of cancers by boosting host immunity.However, radiotherapy is a double-edged sword for PD-1/PD-L immunotherapy. Research on how to improve radiotherapy efficacy using PD-1/PD-L1 inhibitor is gaining momentum. Various studies have reported the survival benefits of the combined application of radiotherapy and PD-1/PD-L1 inhibitor. To fully exerts the immune activation effect of radiotherapy, while avoiding the immunosuppressive effect of radiotherapy as much as possible, the dose selection, segmentation mode, treatment timing and the number of treatment sites of radiotherapy play a role. Therefore, we aim to review the effect of radiotherapy combined with anti-PD-1/PD-L1 on the immune system and its optimization.

Effect of CMNa combined with radiotherapy on the tumor immune microenvironment of mouse cervical cancer cell transplantation tumor model

In this study, we construct a subcutaneous tumor mice model of U14 cells, observe the tumor growth, and detect the expression of Foxp3 and VISTA in cervical cancer tissues and adjacent tissues during CMNa-enhancing radiotherapy.From the 15th day, compared with the control group, the tumor volume changes in each treatment group were significant (P < 0.01). CMNa combined with radiotherapy had an interactive effect and a positive effect in inhibiting tumor volume growth. There was no significant difference in the expression of Foxp3 and VISTA in mouse cervical cancer tissues and adjacent tissues in each group. The Foxp3 level in the RT group was the highest, and the CMNa group was the lowest. The VISTA level of the CMNa+RT group was the highest, the RT group is followed by, and the Control group is the lowest. The Foxp3 level of the CMNa group did not change much at each different point. The Foxp3 level in RT and CMNa+RT group gradually decreased after a transient increase, and the VISTA level in the CMNa+RT group increased more.Our results show that CMNa can enhance the efficacy of radiotherapy, and at the same time can reduce the compensatory increase in regulatory T cell Foxp3 levels caused by radiotherapy, and reduce the radiotherapy response. However, in the course of the treatment of the two, there may be a substantial increase in the level of VISTA, and the combined application of VISTA inhibitors may increase the anti-tumor response.

KRAS mutation: from undruggable to druggable in cancer

Cancer is the leading cause of death worldwide, and its treatment and outcomes have been dramatically revolutionised by targeted therapies. As the most frequently mutated oncogene, Kirsten rat sarcoma viral oncogene homologue (KRAS) has attracted substantial attention. The understanding of KRAS is constantly being updated by numerous studies on KRAS in the initiation and progression of cancer diseases. However, KRAS has been deemed a challenging therapeutic target, even "undruggable", after drug-targeting efforts over the past four decades. Recently, there have been surprising advances in directly targeted drugs for KRAS, especially in KRAS (G12C) inhibitors, such as AMG510 (sotorasib) and MRTX849 (adagrasib), which have obtained encouraging results in clinical trials. Excitingly, AMG510 was the first drug-targeting KRAS (G12C) to be approved for clinical use this year. This review summarises the most recent understanding of fundamental aspects of KRAS, the relationship between the KRAS mutations and tumour immune evasion, and new progress in targeting KRAS, particularly KRAS (G12C). Moreover, the possible mechanisms of resistance to KRAS (G12C) inhibitors and possible combination therapies are summarised, with a view to providing the best regimen for individualised treatment with KRAS (G12C) inhibitors and achieving truly precise treatment.

Improved Immunotherapy Efficacy by Vascular Modulation

Several strategies have been developed to modulate the tumour vasculature for cancer therapy including anti-angiogenesis and vascular normalisation. Vasculature modulation results in changes to the tumour microenvironment including oxygenation and immune cell infiltration, therefore lending itself to combination with cancer therapy. The development of immunotherapies has led to significant improvements in cancer treatment. Particularly promising are immune checkpoint blockade and CAR T cell therapies, which use antibodies against negative regulators of T cell activation and T cells reprogrammed to better target tumour antigens, respectively. However, while immunotherapy is successful in some patients, including those with advanced or metastatic cancers, only a subset of patients respond. Therefore, better predictors of patient response and methods to overcome resistance warrant investigation. Poor, or periphery-limited, T cell infiltration in the tumour is associated with poor responses to immunotherapy. Given that (1) lymphocyte recruitment requires leucocyte-endothelial cell adhesion and (2) the vasculature controls tumour oxygenation and plays a pivotal role in T cell infiltration and activation, vessel targeting strategies including anti-angiogenesis and vascular normalisation in combination with immunotherapy are providing possible new strategies to enhance therapy. Here, we review the progress of vessel modulation in enhancing immunotherapy efficacy.

Irradiation Mediates IFNα and CXCL9 Expression in Non-Small Cell Lung Cancer to Stimulate CD8+ T Cells Activity and Migration toward Tumors

Irradiation-broken DNA fragments increase type I interferon and chemokines secretion in tumor cells. Since radiotherapy may augment tumor immunotherapy, we hypothesize that the chemokines increased by irradiation could recruit CD8⁺ T cells to suppress tumor proliferation. This study intended to unveil the secreted factors activating and recruiting CD8⁺ T cells in non-small-cell lung cancer (NSCLC). EGFR-positive A549 was selected and treated by X-irradiation (IR) to identify the overexpression of chemokines associated to CD8⁺ T cell cytotoxicity and recruitment. A transwell assay with Alexa 488-labeled CD8⁺ T cells was used to evaluate CD8⁺ T cell motility in vitro. A nuclear imaging platform by In¹¹¹-labeled nivolumab was used to track CD8⁺ T cells homing to tumors in vivo. The activation markers GZMB, PRF-1, and IFNγ, migration marker CD183 (CXCR3), and inhibitory marker CD274 (PD-1), were measured and compared in CD8⁺ T cells with A549 co-cultured, chemokines treated, and patients with late-stage lung cancer. We found that IR not only suppressed A549 proliferation but also induced IFNα and CXCL9 expression (p < 0.05). IFNα majorly increased IFNγ levels in CD8⁺ T cells (p < 0.05) and synergistically with CXCL9 enhanced CD8⁺ T cell migration in vitro (p < 0.05). We found that CXCR3 and PD-1 were down-regulated and up-regulated, respectively, in the peripheral blood CD8⁺ T cells in patients with lung cancer (n = 4 vs. healthy n = 3, both p < 0.05), which exhibited reduction of cell motility (p < 0.05). The in vivo nuclear imaging data indicated highly CD8⁺ T cells migrated to A549-induced tumors. In addition, we demonstrated that healthy PBMCs significantly suppressed the parallel tumor growth (p < 0.05) and the radioresistant tumor growth in the tumor xenograft mice (p < 0.05), but PBMCs from patients with lung cancer had lost the anti-tumor capacity. We demonstrated that IR induced IFNα and CXCL9 expression in A549 cells, leading to CD8⁺ T cell migration. This study unveiled a potential mechanism for radiotherapy to activate and recruit CD8⁺ T cells to suppress lung tumors.

Identification of Autophagy Related circRNA-miRNA-mRNA-Subtypes Network With Radiotherapy Responses and Tumor Immune Microenvironment in Non-small Cell Lung Cancer

Lung cancer (LC) is one of the most frequently diagnosed cancers and the leading cause of cancer death worldwide, and most LCs are non-small cell lung cancer (NSCLC). Radiotherapy is one of the most effective treatments for patients with lung cancer, either alone or in combination with other treatment methods. However, radiotherapy responses vary considerably among NSCLC patients. The efficacy of radiotherapy is influenced by several factors, among which autophagy is of importance. Autophagy is induced by radiotherapy and also influences cell responses to radiation. We explored the clinical significance of autophagy-related genes (ARGs) and gene sets (ARGSs) and the underlying mechanism in NSCLC patients treated with radiotherapy. First, differentially expressed ARGs (SNCA, SESN3, DAPL1, and ELAPOR1) and miRNAs (miR-205-5p, miR-26a-1-3p, miR-6510-3p, miR-194-3p, miR-215-5p, and miR-375-3p) were identified between radiotherapy-resistant and radiotherapy-sensitive groups. An autophagy-related radiosensitivity risk signature (ARRS) by nine ARmRNAs/miRNAs and an autophagy-related overall survival risk signature (AROS) by three ARmRNAs were then constructed with estimated AUCs of 0.8854 (95% CI: 0.8131–0.9576) and 0.7901 (95% CI: 0.7168–0.8685), respectively. The correlations between ARGSs or prognostic signatures and clinicopathological factors, short-term radiotherapy responses (radiotherapy sensitivity), long-term radiotherapy responses (overall survival), and immune characteristics were analyzed. Both ARGSs and prognostic signatures were related to immune checkpoint inhibitors (ICIs), infiltration of tumor-infiltrating immune cells (TIICs), and the activity of the cancer immune cycle. Finally, after target prediction and correlation analysis, circRNA (hsa_circ_0019709, hsa_circ_0081983, hsa_circ_0112354, hsa_circ_0040569, hsa_circ_0135500, and hsa_circ_0098966)-regulated miRNA/ARmRNA axes (miR-194-3p/SESN3, miR-205-5p/ELAPOR1, and miR-26a-1-3p/SNCA) were considered potential modulatory mechanisms by influencing the regulation of autophagy, macroautophagy, and chaperone-mediated autophagy.

A mouse model for the study of anti-tumor T cell responses in Kras-driven lung adenocarcinoma

Kras-driven lung adenocarcinoma (LUAD) is the most common lung cancer. A significant fraction of patients with Kras-driven LUAD respond to immunotherapy, but mechanistic studies of immune responses against LUAD have been limited because of a lack of immunotherapy-responsive models. We report the development of the immunogenic KP × NINJA (inversion inducible joined neoantigen) (KP-NINJA) LUAD model. This model allows temporal uncoupling of antigen and tumor induction, which allows one to wait until after infection-induced inflammation has subsided to induce neoantigen expression by tumors. Neoantigen expression is restricted to EPCAM+ cells in the lung and expression of neoantigen was more consistent between tumors than when neoantigens were encoded on lentiviruses. Moreover, tumors were infiltrated by tumor-specific CD8 T cells. Finally, LUAD cell lines derived from KP-NINJA mice were immunogenic and responded to immune checkpoint therapy (anti-PD1 and anti-CTLA4), providing means for future studies into the immunobiology of therapeutic responses in LUAD.

Irradiation Suppresses IFNγ-Mediated PD-L1 and MCL1 Expression in EGFR-Positive Lung Cancer to Augment CD8+ T Cells Cytotoxicity

Tumor cells express immune checkpoints to exhaust CD8⁺ T cells. Irradiation damages tumor cells and augments tumor immunotherapy in clinical applications. However, the radiotherapy-mediated molecular mechanism affecting CD8⁺ T cell activity remains elusive. We aimed to uncover the mechanism of radiotherapy augmenting cytotoxic CD8⁺ T cells in non-small-cell lung cancer (NSCLC). EGFR-positive NSCLC cell lines were co-cultured with CD8⁺ T cells from healthy volunteers. Tumor cell viability and apoptosis were consequently measured. IFNγ was identified secreted by CD8⁺ T cells and PBMCs. Therefore, RNAseq was used to screen the IFNγ-mediated gene expression in A549 cells. The irradiation effect to IFNγ-mediated gene expression was investigated using qPCR and western blots. We found that the co-culture of tumor cells stimulated the increase of granzyme B and IFNγ in CD8⁺ T, but A549 exhibited resistance against CD8⁺ T cytotoxicity compared to HCC827. Irradiation inhibited A549 proliferation and enhanced apoptosis, augmenting PBMCs-mediated cytotoxicity against A549. We found that IFNγ simultaneously increased phosphorylation on STAT1 and STAT3 in EGFR-positive lung cancer, resulting in overexpression of PD-L1 (p < 0.05). In RNAseq analysis, MCL1 was identified and increased by the IFNγ-STAT3 axis (p < 0.05). We demonstrated that irradiation specifically inhibited phosphorylation on STAT1 and STAT3 in IFNγ-treated A549, resulting in reductions of PD-L1 and MCL1 (both p < 0.05). Moreover, knockdowns of STAT3 and MCL1 increased the PBMCs-mediated anti-A549 effect. This study demonstrated that A549 expressed MCL1 to resist CD8⁺ T cell-mediated tumor apoptosis. In addition, we found that irradiation suppressed IFNγ-mediated STAT3 phosphorylation and PD-L1 and MCL1 expression, revealing a potential mechanism of radiotherapy augmenting immune surveillance.

Novel Radiation Therapy Paradigms and Immunomodulation: Heresies and Hope

Radiation therapy benefits the majority of patients across the spectrum of cancer types. However, both local and distant tumor recurrences limit its clinical success. While departing from the established tenet of fractionation in clinical radiotherapy, ablative-intensity hypofractionated radiotherapy, especially stereotactic radiosurgery and stereotactic ablative radiotherapy, has emerged as an alternative paradigm achieving unprecedented rates of local tumor control. Direct tumor cell killing has been assumed to be the primary therapeutic mode of action of such ablative radiation. But with increasing recognition that tumor responses also depend on the immunostimulatory or immunosuppressive status of the tumor microenvironment, the immunologic effect of ablative radiotherapy is emerging as a key contributor to antitumor response. More recently, novel radiation modalities, such as spatially fractionated radiotherapy and ultrahigh dose rate FLASH irradiation, that venture even further from conventional paradigms have shown promise of increasing the therapeutic index of radiation therapy with the potential of immunomodulation. Here, we review the immunomodulatory impact of novel radiation therapy paradigms, heretofore considered radiobiological heresies, a deeper understanding of which is imperative to realizing fully their potential for more curative cancer therapy.

Targeting Pin1 renders pancreatic cancer eradicable by synergizing with immunochemotherapy

Pancreatic ductal adenocarcinoma (PDAC) is characterized by notorious resistance to current therapies attributed to inherent tumor heterogeneity and highly desmoplastic and immunosuppressive tumor microenvironment (TME). Unique proline isomerase Pin1 regulates multiple cancer pathways, but its role in the TME and cancer immunotherapy is unknown. Here, we find that Pin1 is overexpressed both in cancer cells and cancer-associated fibroblasts (CAFs) and correlates with poor survival in PDAC patients. Targeting Pin1 using clinically available drugs induces complete elimination or sustained remissions of aggressive PDAC by synergizing with anti-PD-1 and gemcitabine in diverse model systems. Mechanistically, Pin1 drives the desmoplastic and immunosuppressive TME by acting on CAFs and induces lysosomal degradation of the PD-1 ligand PD-L1 and the gemcitabine transporter ENT1 in cancer cells, besides activating multiple cancer pathways. Thus, Pin1 inhibition simultaneously blocks multiple cancer pathways, disrupts the desmoplastic and immunosuppressive TME, and upregulates PD-L1 and ENT1, rendering PDAC eradicable by immunochemotherapy.

Step-by-Step Immune Activation for Suicide Gene Therapy Reinforcement

Gene-directed enzyme prodrug gene therapy (GDEPT) theoretically represents a useful method to carry out chemotherapy for cancer with minimal side effects through the formation of a chemotherapeutic agent inside cancer cells. However, despite great efforts, promising preliminary results, and a long period of time (over 25 years) since the first mention of this method, GDEPT has not yet reached the clinic. There is a growing consensus that optimal cancer therapies should generate robust tumor-specific immune responses. The advent of checkpoint immunotherapy has yielded new highly promising avenues of study in cancer therapy. For such therapy, it seems reasonable to use combinations of different immunomodulators alongside traditional methods, such as chemotherapy and radiotherapy, as well as GDEPT. In this review, we focused on non-viral gene immunotherapy systems combining the intratumoral production of toxins diffused by GDEPT and immunomodulatory molecules. Special attention was paid to the applications and mechanisms of action of the granulocyte-macrophage colony-stimulating factor (GM–CSF), a cytokine that is widely used but shows contradictory effects. Another method to enhance the formation of stable immune responses in a tumor, the use of danger signals, is also discussed. The process of dying from GDEPT cancer cells initiates danger signaling by releasing damage-associated molecular patterns (DAMPs) that exert immature dendritic cells by increasing antigen uptake, maturation, and antigen presentation to cytotoxic T-lymphocytes. We hypothesized that the combined action of this danger signal and GM–CSF issued from the same dying cancer cell within a limited space would focus on a limited pool of immature dendritic cells, thus acting synergistically and enhancing their maturation and cytotoxic T-lymphocyte attraction potential. We also discuss the problem of enhancing the cancer specificity of the combined GDEPT–GM–CSF–danger signal system by means of artificial cancer specific promoters or a modified delivery system.