Radiation therapy enhanced therapeutic efficacy of anti-PD1 against gastric cancer

Association between adjuvant radiotherapy in adults with gastric cancer and risk of second primary malignancy: a retrospective cohort study using the Surveillance, Epidemiology and End Results database

OBJECTIVES

This study aims to assess the association between adjuvant radiotherapy and the development of second primary malignancies (SPMs) and identify its determinants in patients who have undergone surgical treatment for gastric cancer.

DESIGN

Retrospective cohort study using the Surveillance, Epidemiology and End Results (SEER) database.

SETTING

Cohorts (18 registries, 2000-2018, from SEER) were screened for any malignancy that developed after sufficient latency from diagnosis of surgically treated non-metastatic gastric cancer.

PARTICIPANTS

24 777 surgically treated gastric cancer cases were included in the cohort. Among them, 6128 patients underwent adjuvant radiotherapy.

OUTCOME MEASURES

The cumulative incidence of SPMs was estimated using Fine and Gray's competing risk model and the radiotherapy-correlated risks were calculated using Poisson regression analysis.

RESULTS

Among patients with sufficient latency, there was no significant association between radiotherapy and the risk of developing second primary solid malignancies (relative risk=1.05, 95% CI 0.83 to 1.33) or haematological malignancies (relative risk=1.17, 95% CI 0.62 to 2.11). Interestingly, radiotherapy was associated with a reduced cumulative incidence of second lung and bronchus cancer compared with no radiotherapy, with a 15-year incidence of 1.4%-3.17% (p<0.05). Radiotherapy was not associated with a significant increase in standardised incidence ratios of SPMs.

CONCLUSIONS

Adjuvant radiotherapy was not associated with an increased risk of developing SPMs in surgically treated patients with gastric cancer. Clinical trials are warranted to further verify the findings.

Programmed death receptor-1/programmed death-ligand 1 inhibitors: Clinical progress and biomarker exploration in gastric cancer

Gastric cancer is one of the most common malignant tumours, with limited treatment options and poor prognosis in its advanced stages. In recent years, breakthroughs in tumour immunotherapy have led to immune checkpoint inhibitors becoming a new class of clinical oncology drugs. Programmed death receptor-1 (PD-1) and programmed death-ligand 1 (PD-L1) play significant roles in inhibiting T cell responses and tumour immune escape. PD-1/PD-L1 inhibitors can significantly improve the prognosis of patients with advanced gastric cancer. Moreover, the combination of administering PD-1/PD-L1 inhibitors along with chemotherapy, radiotherapy, targeted therapy, and other immunotherapies may further enhance therapeutic efficacy. However, some scientific issues need to be urgently resolved in the immunotherapy of gastric cancer, including the suboptimal efficacy of PD-1/PD-L1 inhibitor monotherapy, high incidence of immune-related adverse events, and the absence of definitive biomarkers for effectively screening treatment-sensitive populations. This article reviews the mechanism of action, therapeutic advances, adverse effects, and putative predictive biomarkers of PD-1/PD-L1 inhibitors in the treatment of advanced gastric cancer.

The cGAS/STING Pathway-A New Potential Biotherapeutic Target for Gastric Cancer?

Gastric cancer ranks among the top five deadliest tumors worldwide, both in terms of prevalence and mortality rates. Despite mainstream treatments, the efficacy in treating gastric cancer remains suboptimal, underscoring the urgency for novel therapeutic approaches. The elucidation of tumor immunosuppressive microenvironments has shifted focus towards cancer biotherapeutics, which leverage the patient's immune system or biologics to target tumor cells. Biotherapy has emerged as a promising alternative for tumors resistant to traditional chemotherapy, radiation, and immunotherapy. Central to this paradigm is the cGAS-STING pathway, a pivotal component of the innate immune system. This pathway recognizes aberrant DNA, such as that from viral infections or tumor cells, and triggers an immune response, thereby reshaping the immunosuppressive tumor microenvironment into an immune-stimulating milieu. In the context of gastric cancer, harnessing the cGAS-STING pathway holds significant potential for biotherapeutic interventions. This review provides a comprehensive overview of the latest research on cGAS-STING in gastric cancer, including insights from clinical trials involving STING agonists. Furthermore, it assesses the prospects of targeting the cGAS-STING pathway as a novel biotherapeutic strategy for gastric cancer.

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.

Pembrolizumab and low-dose, single-fraction radiotherapy for patients with relapsed or refractory multiple myeloma: a prospective, single-centre, single-group, open-label, phase 2 pilot trial in the USA

BACKGROUND

Currently, the use of radiotherapy alone for people with multiple myeloma is limited to palliation of pain, pending fracture, and control of spinal-cord compression. Single immune-checkpoint inhibitors, such as anti-programmed death-1 (anti-PD1), have not been successful. We aimed to evaluate the activity and safety of the combination of pembrolizumab and low-dose, single-fraction, hypofractionated radiotherapy to treat patients with relapsed or refractory multiple myeloma.

METHODS

For this prospective, single-centre, single-group, open-label, phase 2 trial, we recruited patients with relapsed or refractory multiple myeloma from the Winship Cancer Institute (Emory University, Atlanta, GA, USA). Key inclusion criteria were aged 18 years or older, Eastern Cooperative Oncology Group (ECOG) performance score of 0 or 1, relapsed or refractory multiple myeloma as indicated by progression under International Myeloma Working Group (IMWG) criteria, and adequate candidacy for both pembrolizumab and radiotherapy. Baseline and post-treatment assessments were serial bone-marrow biopsy, peripheral blood collections, staging, serial serum and urine paraprotein analysis, serial PET-CT imaging, and a physical examination. On day 1, patients received hypofractionated 8 gray in 1 fraction (8 Gy/1 fx) radiotherapy to either symptomatic or progressing extra-osseous or osseous myeloma sites. Patients also received pembrolizumab (200 mg/kg intravenously) on day 2 or 3, then once every 3 weeks (±7 days) for 2 years or until progressive disease, unacceptable toxicity, withdrawal of consent, loss to follow-up, or death. Dose reduction and interruptions were not allowed. The primary outcome was acute toxicity defined as grade 3 or worse toxicity at 3 months within the radiated site when used in combination with pembrolizumab. All patients were analysed per protocol and included in safety analyses. This trial is registered on ClinicalTrials.gov (NCT03267888); it is completed and closed to accrual.

FINDINGS

32 patients were screened between June 1, 2018, and Sept 2, 2022, and 25 were enrolled in the trial and treated on protocol. Of the 25 treated patients, 11 (44%) were female and 14 (56%) were male. 19 (76%) patients were White and six (24%) were Black or African American. Toxicity, as the primary outcome, was deemed to be acceptable as no grade 4 or 5 adverse events were observed. At 3-month follow-up, eight (32%) of 25 patients had treatment benefit (one had stable disease, three had partial response, two had very good partial response, and two had complete response). There was no grade 3 or worse radiation-related toxicity within irradiated volumes. One (4%) patient of the 25 who received combination treatment had a grade 3 pembrolizumab-related adverse event. There were no treatment-related deaths.

INTERPRETATION

Combination treatment of low-dose, single-fraction radiotherapy with pembrolizumab was safe, with early promise of response activity. Our approach could be an option for patients with relapsed or refractory multiple myeloma who have not responded to previous treatment. Larger trials to substantiate our findings are needed.

FUNDING

Merck Sharp & Dohme.

Beyond success: unveiling the hidden potential of radiotherapy and immunotherapy in solid tumors

Immunotherapy, particularly with immune checkpoint inhibitors, has significantly transformed cancer treatment. Despite its success, many patients struggle to respond adequately or sustain long-lasting clinical improvement. A growing consensus has emerged that radiotherapy (RT) enhances the response rate and overall efficacy of immunotherapy. Although combining RT and immunotherapy has been extensively investigated in preclinical models and has shown promising results, establishing itself as a dynamic and thriving area of research, clinical evidence for this combination strategy over the past five years has shown both positive and disappointing results, suggesting the need for a more nuanced understanding. This review provides a balanced and updated analysis of the combination of immunotherapy and RT. We summarized the preclinical mechanisms through which RT boosts antitumor immune responses and mainly focused on the outcomes of recently updated clinical trials, including those that may not have met expectations. We investigated the optimization of the therapeutic potential of this combined strategy, including key challenges, such as fractionation and scheduling, lymph node irradiation, and toxicity. Finally, we offered insights into the prospects and challenges associated with the clinical translation of this combination therapy, providing a realistic perspective on the current state of research and potential future directions.

CD45- erythroid progenitor cells promote lymph node metastasis in gastric cancer by inducing a hybrid epithelial/mesenchymal state in lymphatic endothelial cells

BACKGROUND AND AIMS

Specific mechanisms of lymph node (LN) metastasis in early-stage gastric cancer (GC) have not been elucidated. The role of anemia, a vital clinical feature of GC, in LN metastasis is also unclear. Since the number of erythroid progenitor cells (EPCs) is increased in chronic anemia, we investigated its association with LN metastasis in GC.

METHODS

Flow cytometry and immunofluorescence analyses were performed to sort and study EPCs from the circulation and tumors of patients with stage I-III GC. The effect of these EPCs on the activation of T and B cells and on the functions of lymphatic endothelial cells (LECs) was determined, and their ability to promote LN metastasis was evaluated using a footpad-popliteal LN metastasis model based on two human adenocarcinoma GC cell lines in nude mice. The prognostic value of EPCs was also analyzed.

RESULTS

The proportion of CD45- EPCs was higher in the mononuclear cells in the circulation, tumors, and LNs of GC patients with LN metastasis (N+) than in those of GC patients without LN metastasis (N0). In N+ patients, CD45- EPCs were more abundant in metastatic LNs than in non-metastatic LNs. Lymphatic vessel endothelial hyaluronan receptor 1 immunoreactivity in tumors revealed that CD45- EPCs were positively associated with nodal stages and lymph vessel density. Furthermore, CD45- EPCs increased LEC proliferation and migration through their S100A8/A9 heterodimer-induced hybrid epithelial/mesenchymal (E/M) state; however, they did not influence the invasion and tubulogenesis of LECs or T and B cell proliferation. CD45- EPCs promoted LN metastasis in vivo; the S100A8/A9 heterodimer mimicked this phenomenon. Finally, CD45- EPCs predicted the overall and disease-free survival of stage I-III GC patients after radical resection.

CONCLUSIONS

The CD45- EPCs accumulated in GC tissues and metastatic LNs and promoted LN metastasis via the S100A8/9-induced hybrid E/M state of LECs, which was the specific mechanism of LN metastasis in the early stages of GC.

Efficacy of anti-programmed cell death protein 1 monoclonal antibody combined with bevacizumab and/or Pseudomonas aeruginosa injection in transplanted tumor of mouse forestomach carcinoma cell gastric cancer in mice and its mechanism in regulating tumor immune microenvironment

Tumor immunotherapy represented by programmed cell death protein 1 (PD-1) inhibitors is considered as the most promising cancer treatment method and has been widely used in the treatment of advanced gastric cancer (GC). However, the effective rate of PD-1 inhibitor monotherapy is low. In this study, we constructed a transplanted tumor model in GC mice by inoculating mouse forestomach carcinoma cell (MFC) GC cells into 615 mice. Interventions were conducted with normal saline, anti-PD-1 monoclonal antibody (mAb), bevacizumab, Pseudomonas aeruginosa-mannose-sensitive hemagglutinin (PA-MSHA), anti-PD-1 mAb combined with bevacizumab, anti-PD-1 mAb combined with PA-MSHA, bevacizumab combined with PA-MSHA, anti-PD-1 mAb combined with bevacizumab and PA-MSHA, respectively. The tumor growth curves were drawn. TUNEL assay, western blotting, and immunohistochemistry were used to detect tumor proliferation and apoptosis. Flow cytometry and ELISA were used to detect the expression of tumor infiltrating lymphocytes and cytokines. This study found that anti-PD-1 mAb alone could not significantly inhibit the growth of transplanted tumors in mice. Anti-PD-1 mAb combined with bevacizumab, anti-PD-1 mAb combined with PA-MSHA, anti-PD-1 mAb combined with bevacizumab and PA-MSHA could all significantly inhibit tumor growth in mice, and the combination of three drugs presented the highest tumor inhibition rate. Anti-PD-1 mAb combined with bevacizumab and PA-MSHA could significantly upregulate the number of Th1-type cells, CD8 + T cells, and Type I tumor-associated macrophages (TAMs), while downregulate the number of Th2-type cells, myeloid-derived suppressor cells, regulatory T cells, and Type II TAMs. Therefore, we conclude that anti-PD-1 mAb combined with bevacizumab and/or PA-MSHA has a synergistic effect. Bevacizumab and PA-MSHA can transform the tumor immunosuppressive microenvironment into a supportive immune microenvironment, thus maximizing the antitumor effect of anti-PD-1 mAb.

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.

Combination of Immunotherapy and Radiation Therapy in Gastrointestinal Cancers: An Appraisal of the Current Literature and Ongoing Research

Oncological outcomes are improving in gastrointestinal cancer with advancements in systemic therapies, and there is notable potential in combining immunotherapy and radiation therapy (RT) to allow for further improvements. Various preclinical and early phase II studies have shown promising synergy with immunotherapy and RT in gastrointestinal cancer. A few recent phase III studies have shown improved survival with the addition of immunotherapy to standard treatment for gastrointestinal cancer. The timing, duration, sequencing, and integration with other anti-cancer treatments are still areas of ongoing research. We have reviewed the published and ongoing studies of the combinations of immunotherapy and RT in gastrointestinal cancers.

Enhanced tumor inhibiting effect of 131I-BDI-1-based radioimmunotherapy and cytosine deaminase gene therapy modulated by a radio-sensitive promoter in nude mice bearing bladder cancer

Radioimmunotherapy (RIT) has great potential in cancer therapy. However, its efficacy in numerous tumors is restricted due to myelotoxicity, thereby limiting the dose of radionuclide. To increase tumor radiosensitivity, we incorporated the recombinant lentivirus into the EJ cells (bladder cancer [BC] cells), and examined the combined anti-tumor effects of RIT with 131I-BDI-1(131I-monoclonal antibody against human BC-1) and gene therapy (GT). The recombinant lentivirus was constructed and packed. The animal xenograft model was built and when the tumor reached about 0.5 cm in diameter, the mice were randomly separated into four groups: (1) RIT + GT: the xenografts were continuously incorporated with the recombinant lentivirus for two days. And 7.4 MBq 131I-BDI-1 was IV-injected, and 10 mg prodrug 5-fluorocytosine (FC) was IV-injected for 7 days, (2) RIT: same dose of 131I-BDI-1 as the previous group mice, (3) GT: same as the first group, except no 131I-BDI-1, and (4) Untreated. Compute tumor volumes in all groups. After 28 days the mice were euthanized and the tumors were extracted and weighed, and the inhibition rate was computed. The RIT + GT mice, followed by the RIT mice, exhibited markedly slower tumor growth, compared to the control mice. The tumor size was comparable between the GT and control mice. The tumor inhibition rates after 28 days of incubation were 42.85 ± 0.23%, 27.92 ± 0.21% and 0.57 ± 0.11% for the four groups, respectively. In conclusion, RIT, combined with GT, suppressed tumor development more effectively than RIT or GT alone. This data highlights the potent additive effect of radioimmune and gene therapeutic interventions against cancer.

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.

Carbon ion radiotherapy triggers immunogenic cell death and sensitizes melanoma to anti-PD-1 therapy in mice

Carbon ion radiotherapy (CIRT) is an emerging type of radiotherapy for the treatment of solid tumors. In recent years, evidence accumulated that CIRT improves the therapeutic outcome in patients with otherwise poor response to immune checkpoint blockade. Here, we aimed at identifying the underlying mechanisms of CIRT-induced tumor immunogenicity and treatment efficacy. We used human U2OS osteosarcoma cells for the in vitro assessment of immunogenic cell death and established several in vivo models of melanoma in mice. We treated the animals with conventional radiation, CIRT, PD-1-targeting immune checkpoint blockade or a sequential combinations of radiotherapy with checkpoint blockade. We utilized flow cytometry, polyacrylamide gel electrophoresis (PAGE) and immunoblot analysis, immunofluorescence, immunohistochemistry, as well as enzyme-linked immunosorbent assays (ELISA) to assess biomarkers of immunogenic cell death in vitro. Treatment efficacy was studied by tumor growth assessment and the tumor immune infiltrate was analyzed by flow cytometry and immunohistochemistry. Compared with conventional radioimmunotherapy, the combination of CIRT with anti-PD-1 more efficiently triggered traits of immunogenic cell death including the exposure of calreticulin, the release of adenosine triphosphate (ATP), the exodus of high-mobility group box 1 (HMGB1) as well as the induction of type-1 interferon responses. In addition, CIRT plus anti-PD-1 led to an increased infiltration of CD4⁺, and CD8⁺ lymphocytes into the tumor bed, significantly decreased tumor growth and prolonged survival of melanoma bearing mice. We herein provide evidence that CIRT-triggered immunogenic cell death, enhanced tumor immunogenicity and improved the efficacy of subsequent anti-PD-1 immunotherapy.

cGAS-STING signaling pathway in gastrointestinal inflammatory disease and cancers

Cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway has emerged as a key DNA-sensing machinery in innate immunity. Activation of cGAS-STING signaling pathway mediates the production of interferons and proinflammatory cytokines. Although cGAS-STING signaling pathway shows critical function in the maintenance of gut homeostasis, overactive cGAS-STING signaling pathway leads to gastrointestinal (GI) inflammation. Harnessing the effect and mechanism of the cGAS-STING signaling pathway could be beneficial for the development of novel strategies for the treatment of GI diseases. This review presents recent advances regarding the role of cGAS-STING signaling pathway in GI inflammatory disease and cancers and describes perspective therapeutic strategies targeting the signaling pathway.

Carbon-ion Radiotherapy for Colorectal Cancer

Heavy-ion radiotherapy (RT) is a kind of particle RT, and carbon-ion beam constitutes the primary delivery method of heavy-ion RT. Unlike the conventional photon modalities, particle RT, in particular carbon-ion radiotherapy (CIRT), offers unique physical and biological advantages. Particle therapy allows for substantial dose delivery to tumors with minimal surrounding tissue damage. In addition, CIRT in particular possesses biological advantages such as inducing increased double-strand breaks in DNA structures, causing irreversible cell damage independently of cell cycle or oxygenation, more so than proton or photon. It can be expected that CIRT is effective on radioresistant cancers such as colorectal cancers (CRCs). We introduced the results of CIRT for local recurrent rectal cancer, lung metastasis, liver metastasis, and lymph node metastasis.