Abscopal Benefits of Localized Radiotherapy Depend on Activated T-cell Trafficking and Distribution between Metastatic Lesions

A Role of Effector CD 8 + T Cells Against Circulating Tumor Cells Cloaked with Platelets: Insights from a Mathematical Model

Cancer metastasis accounts for a majority of cancer-related deaths worldwide. Metastasis occurs when the primary tumor sheds cells into the blood and lymphatic circulation, thereby becoming circulating tumor cells (CTCs) that transverse through the circulatory system, extravasate the circulation and establish a secondary distant tumor. Accumulating evidence suggests that circulating effector CD 8 + T cells are able to recognize and attack arrested or extravasating CTCs, but this important antitumoral effect remains largely undefined. Recent studies highlighted the supporting role of activated platelets in CTCs's extravasation from the bloodstream, contributing to metastatic progression. In this work, a simple mathematical model describes how the primary tumor, CTCs, activated platelets and effector CD 8 + T cells participate in metastasis. The stability analysis reveals that for early dissemination of CTCs, effector CD 8 + T cells can present or keep secondary metastatic tumor burden at low equilibrium state. In contrast, for late dissemination of CTCs, effector CD 8 + T cells are unlikely to inhibit secondary tumor growth. Moreover, global sensitivity analysis demonstrates that the rate of the primary tumor growth, intravascular CTC proliferation, as well as the CD 8 + T cell proliferation, strongly affects the number of the secondary tumor cells. Additionally, model simulations indicate that an increase in CTC proliferation greatly contributes to tumor metastasis. Our simulations further illustrate that the higher the number of activated platelets on CTCs, the higher the probability of secondary tumor establishment. Intriguingly, from a mathematical immunology perspective, our simulations indicate that if the rate of effector CD 8 + T cell proliferation is high, then the secondary tumor formation can be considerably delayed, providing a window for adjuvant tumor control strategies. Collectively, our results suggest that the earlier the effector CD 8 + T cell response is enhanced the higher is the probability of preventing or delaying secondary tumor metastases.

Optimal dosage protocols for mathematical models of synergy of chemo- and immunotherapy

The release of tumor antigens during traditional cancer treatments such as radio- or chemotherapy leads to a stimulation of the immune response which provides synergistic effects these treatments have when combined with immunotherapies. A low-dimensional mathematical model is formulated which, depending on the values of its parameters, encompasses the 3 E's (elimination, equilibrium, escape) of tumor immune system interactions. For the escape situation, optimal control problems are formulated which aim to revert the process to the equilibrium scenario. Some numerical results are included.

Simulating tumor volume dynamics in response to radiotherapy: Implications of model selection

From the beginning of the usage of radiotherapy (RT) for cancer treatment, mathematical modeling has been integral to understanding radiobiology and for designing treatment approaches and schedules. There has been extensive modeling of response to RT with the inclusion of various degrees of biological complexity. In this study, we compare three models of tumor volume dynamics: (1) exponential growth with RT directly reducing tumor volume, (2) logistic growth with direct tumor volume reduction, and (3) logistic growth with RT reducing the tumor carrying capacity with the objective of understanding the implications of model selection and informing the process of model calibration and parameterization. For all three models, we: examined the rates of change in tumor volume during and RT treatment course; performed parameter sensitivity and identifiability analyses; and investigated the impact of the parameter sensitivity on the tumor volume trajectories. In examining the tumor volume dynamics trends, we coined a new metric - the point of maximum reduction of tumor volume (MRV) - to quantify the magnitude and timing of the expected largest impact of RT during a treatment course. We found distinct timing differences in MRV, dependent on model selection. The parameter identifiability and sensitivity analyses revealed the interdependence of the different model parameters and that it is only possible to independently identify tumor growth and radiation response parameters if the underlying tumor growth rate is sufficiently large. Ultimately, the results of these analyses help us to better understand the implications of model selection while simultaneously generating falsifiable hypotheses about MRV timing that can be tested on longitudinal measurements of tumor volume from pre-clinical or clinical data with high acquisition frequency. Although, our study only compares three particular models, the results demonstrate that caution is necessary in selecting models of response to RT, given the artifacts imposed by each model.

Transport Barriers Influence the Activation of Anti-Tumor Immunity: A Systems Biology Analysis

Effective anti-cancer immune responses require activation of one or more naïve T cells. If the correct naïve T cell encounters its cognate antigen presented by an antigen presenting cell, then the T cell can activate and proliferate. Here, mathematical modeling is used to explore the possibility that immune activation in lymph nodes is a rate-limiting step in anti-cancer immunity and can affect response rates to immune checkpoint therapy. The model provides a mechanistic framework for optimizing cancer immunotherapy and developing testable solutions to unleash anti-tumor immune responses for more patients with cancer. The results show that antigen production rate and trafficking of naïve T cells into the lymph nodes are key parameters and that treatments designed to enhance tumor antigen production can improve immune checkpoint therapies. The model underscores the potential of radiation therapy in augmenting tumor immunogenicity and neoantigen production for improved ICB therapy, while emphasizing the need for careful consideration in cases where antigen levels are already sufficient to avoid compromising the immune response.

Treatment of evolving cancers will require dynamic decision support

Cancer research has traditionally focused on developing new agents, but an underexplored question is that of the dose and frequency of existing drugs. Based on the modus operandi established in the early days of chemotherapies, most drugs are administered according to predetermined schedules that seek to deliver the maximum tolerated dose and are only adjusted for toxicity. However, we believe that the complex, evolving nature of cancer requires a more dynamic and personalized approach. Chronicling the milestones of the field, we show that the impact of schedule choice crucially depends on processes driving treatment response and failure. As such, cancer heterogeneity and evolution dictate that a one-size-fits-all solution is unlikely-instead, each patient should be mapped to the strategy that best matches their current disease characteristics and treatment objectives (i.e. their 'tumorscape'). To achieve this level of personalization, we need mathematical modeling. In this perspective, we propose a five-step 'Adaptive Dosing Adjusted for Personalized Tumorscapes (ADAPT)' paradigm to integrate data and understanding across scales and derive dynamic and personalized schedules. We conclude with promising examples of model-guided schedule personalization and a call to action to address key outstanding challenges surrounding data collection, model development, and integration.

Preoperative Radiotherapy Does Not Change the Existing Treatment Paradigm in Stage III Breast Cancer

INTRODUCTION

Radiotherapy (RT) plays an indispensable role in postoperative breast cancer treatment. This study aimed to assess the feasibility of preoperative RT for stage III breast cancer by comparing preoperative RT with postoperative RT in terms of overall survival (OS).

METHODS

Based on the information in the Surveillance, Epidemiology, and End Results database from 2000 to 2018, patients with stage III breast cancer who had undergone radical surgery and RT were divided into two groups: a preoperative RT group and a postoperative RT group. OS was calculated using Kaplan-Meier analysis. The Cox proportional hazards model was used to evaluate independent factors associated with OS. Propensity score matching (PSM) was used to balance stratification factors.

RESULTS

In total, 9,605 patients were enrolled, of whom 9,456 received postoperative RT and 149 received preoperative RT. After a median follow-up of 72 months, postoperative RT was found to be superior to preoperative RT in terms of OS (p < 0.000). Compared to the postoperative RT group, the preoperative RT group showed a significantly higher risk of overall mortality without PSM in univariate (OS: hazard ratio [HR] = 1.653, 95% confidence interval [CI]: 1.288-2.123, p < 0.000) and multivariate analyses (OS: HR = 1.409, 95% CI: 1.096-1.810, p = 0.007). After PSM, the OS of the postoperative RT group was superior to the OS in the preoperative RT group (p = 0.041). Compared with the postoperative RT group, the preoperative RT group showed a significantly higher risk of overall mortality without PSM in univariate (HR = 1.312, 95% CI: 1.010-1.704, p = 0.042) and multivariate analyses (HR = 1.466, 95% CI: 1.127-1.906, p = 0.004).

CONCLUSION

Preoperative RT does not improve OS in patients with stage III breast cancer and has a worse prognosis. Preoperative RT has not changed the existing treatment paradigm in the current therapeutic context for patients with stage III breast cancer.

Combining stereotactic body radiotherapy with immunotherapy in stage IV non-small cell lung cancer

Immunotherapy has revolutionized the treatment of metastatic non-small cell lung cancer (NSCLC). Oligometastasis has been associated with better prognosis than widespread metastatic disease and may be curable by stereotactic body radiotherapy (SBRT). SBRT can stimulate immunogenic anti-tumor activity, which can be further augmented when combined with immunotherapy, such as immune checkpoint inhibitors (ICIs). Thus, its combination with immunotherapy was recognized as a promising treatment option, especially in the metastatic setting. However, the most optimal approach to combine SBRT with immunotherapy remains controversial with early clinical evidence emerging. Here, we review the current clinical evidence supporting the combination of SBRT with immunotherapy in the treatment of metastatic NSCLC. Also, we discuss the current controversies and areas for further exploration associated with this treatment strategy.

New Opportunities to Individualize Frontline Therapy in Advanced Stages of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a leading cause of cancer death globally and is rising in incidence. Until recently, treatment options for patients with advanced stages of HCC have been limited to antiangiogenic therapies with modest improvements in overall survival. The emerging role of immunotherapy with immune checkpoint inhibitors (ICI) in oncology has led to a rapid expansion in treatment options and improvements in outcomes for patients with advanced stages of HCC. Recent clinical trials have shown meaningful survival improvement in patients treated with the combination of bevacizumab and atezolizumab, as well as with the combination of tremelimumab with durvalumab, resulting in regulatory approvals of these regimens as frontline therapy. Beyond improvements in overall survival, ICI-based combination regimens achieve higher rates of durable treatment response than multikinase inhibitors and have favorable side effect profiles. With the emergence of doublet anti-angiogenic and immune checkpoint inhibitor (ICI) and dual ICI combinations, individualized therapy is now possible for patients based on co-morbidity profiles and other factors. These more potent systemic therapies are also being tested in earlier stages of disease and in combination with loco-regional therapies such as trans-arterial chemoembolization and stereotactic body radiotherapy. We summarize these advances and emerging therapeutic combinations currently in clinical trials.

The RadScopal Technique as an Immune Adjuvant to Treat Cancer

Since the momentous discovery of X-rays, high-dose radiotherapy (H-XRT) has been a cornerstone for combating cancer. The high-energy electromagnetic waves induce direct damage to tumor-cells’ DNA, thereby halting cell growth and proliferation, and eventually leading to tumor eradication. Furthermore, recent evidence suggests that H-XRT may have immunomodulatory properties which arise from its ability to induce the release of neoantigens, which in turn prime T-cells and contribute to T-cell repertoire diversity. Throughout the years, there have been different treatment modalities introduced as complements to H-XRT that have yielded greater results than monotherapy alone. In this review, we will discuss preclinical and clinical data related to the recently introduced low-dose radiotherapy (L-XRT) modality. We will also explore the justification for combining L-XRT and H-XRT, which became known as the “RadScopal Technique”, as a novel immune adjuvant to treat cancer. In this analysis, we detail and dissect the physiological mechanisms of action of each modality and describe the synergistic amalgamation effect observed on primary and metastatic tumors. Finally, we will explore the impetus for further studies to investigate combinations of the “RadScopal Technique” with various immune-oncology drug candidates.

Immune checkpoint inhibitors and Carbon iON radiotherapy In solid Cancers with stable disease (ICONIC)

ICONIC is a multicenter, open-label, nonrandomized phase II clinical trial aiming to assess the feasibility and clinical activity of the addition of carbon ion radiotherapy to immune checkpoint inhibitors in cancer patients who have obtained disease stability with pembrolizumab administered as per standard-of-care. The primary end point is objective response rate, and the secondary end points are safety, survival and disease control rate. Translational research is an exploratory aim. The planned sample size is 27 patients. The study combination will be considered worth investigating if at least four objective responses are observed. If the null hypothesis is rejected, ICONIC will be the first proof of concept of the feasibility and clinical activity of the addition of carbon ion radiotherapy to immune checkpoint inhibitors in oncology.

Overcoming immune-resistance in laryngeal cancer: a case report of the abscopal effect and nivolumab beyond progression

The abscopal effect is defined as the systemic regression of distant neoplastic lesions induced by localized treatment. Although the first case reports date back to the beginning of the twentieth century, it remains a very rare event. In recent years, research and reporting on the subject has increased thanks to the development of new immune-checkpoint inhibitors (ICIs) and stereotactic body radiotherapy, as a consequence of molecular and clinical synergism. This work describes an extremely particular presentation of metastatic laryngeal cancer, with mediastinal abdominal nodes and bone progressive disease after PD-1 inhibitor failure, which resulted in reductions of bone pain and abdominal and thoracic lymphadenopathies and an improvement in clinical conditions after treatment with concurrent palliative radiotherapy on the bulky mediastinal node and ICI beyond progression, configuring an important abscopal response.

Survival comparison between postoperative and preoperative radiotherapy for stage I-III non-inflammatory breast cancer

To compare the survival benefit between preoperative and postoperative radiotherapy for stage I-III non-inflammatory breast cancer patients, we conducted a retrospective cohort study using surveillance, epidemiology and end results databases. Our study recruited patients who had been diagnosed with stage I-III breast cancer and underwent surgery and radiotherapy. The overall survival was calculated by Kaplan-Meier method. Cox risk model was used to determine the impact of radiotherapy according to stage, molecular subtype and other risk factors. Propensity score matching was used to balance measurable confounding factors. Of all the 411,279 enrolled patients varying from 1975 to 2016, 1712 patients received preoperative radiotherapy, and 409,567 patients received postoperative radiotherapy. Compared with the postoperative radiotherapy group, the preoperative radiotherapy group showed significantly higher risks of overall mortality and breast cancer-specific mortality. Survival differences in treatment sequences were correlated with stage, molecular subtypes and other risk factors. According to the results of this study, preoperative radiotherapy did not show a survival advantage, and postoperative radiotherapy is still the primary treatment. However, preoperative radiotherapy also has some theoretical advantages, such as phase reduction and recurrence reduction. Therefore, it is still worthy of further exploration.

Analysis of cellular kinetic models suggest that physiologically based model parameters may be inherently, practically unidentifiable

Physiologically-based pharmacokinetic and cellular kinetic models are used extensively to predict concentration profiles of drugs or adoptively transferred cells in patients and laboratory animals. Models are fit to data by the numerical optimisation of appropriate parameter values. When quantities such as the area under the curve are all that is desired, only a close qualitative fit to data is required. When the biological interpretation of the model that produced the fit is important, an assessment of uncertainties is often also warranted. Often, a goal of fitting PBPK models to data is to estimate parameter values, which can then be used to assess characteristics of the fit system or applied to inform new modelling efforts and extrapolation, to inform a prediction under new conditions. However, the parameters that yield a particular model output may not necessarily be unique, in which case the parameters are said to be unidentifiable. We show that the parameters in three published physiologically-based pharmacokinetic models are practically (deterministically) unidentifiable and that it is challenging to assess the associated parameter uncertainty with simple curve fitting techniques. This result could affect many physiologically-based pharmacokinetic models, and we advocate more widespread use of thorough techniques and analyses to address these issues, such as established Markov Chain Monte Carlo and Bayesian methodologies. Greater handling and reporting of uncertainty and identifiability of fit parameters would directly and positively impact interpretation and translation for physiologically-based model applications, enhancing their capacity to inform new model development efforts and extrapolation in support of future clinical decision-making.

The cellular and molecular mediators of metastasis to the lung

Organ-specific metastasis to secondary organs is dependent on the formation of a supportive pre-metastatic niche. This tissue-specific microenvironmental response is thought to be mediated by mutational and epigenetic changes to primary tumour cells resulting in altered cross-talk between cell types. This response is augmented through the release of tumour and stromal signalling mediators including cytokines, chemokines, exosomes and growth factors. Although researchers have elucidated some of the cancer-promoting features that are bespoke to organotropic metastasis to the lungs, it remains unclear if these are organ-specific or generic between organs. Understanding the mechanisms that mediate the metastasis-promoting synergy between the host microenvironment, immunity, and pulmonary structures may elucidate predictive, prognostic and therapeutic markers that could be targeted to reduce the metastatic burden of disease. Herein, we give an updated summary of the known cellular and molecular mechanisms that contribute to the formation of the lung pre-metastatic niche and tissue-specific metastasis.

Radiotherapy combined with immunotherapy: the dawn of cancer treatment

Radiotherapy (RT) is delivered for purposes of local control, but can also exert systemic effect on remote and non-irradiated tumor deposits, which is called abscopal effect. The view of RT as a simple local treatment has dramatically changed in recent years, and it is now widely accepted that RT can provoke a systemic immune response which gives a strong rationale for the combination of RT and immunotherapy (iRT). Nevertheless, several points remain to be addressed such as the interaction of RT and immune system, the identification of the best schedules for combination with immunotherapy (IO), the expansion of abscopal effect and the mechanism to amplify iRT. To answer these crucial questions, we roundly summarize underlying rationale showing the whole immune landscape in RT and clinical trials to attempt to identify the best schedules of iRT. In consideration of the rarity of abscopal effect, we propose that the occurrence of abscopal effect induced by radiation can be promoted to 100% in view of molecular and genetic level. Furthermore, the “radscopal effect” which refers to using low-dose radiation to reprogram the tumor microenvironment may amplify the occurrence of abscopal effect and overcome the resistance of iRT. Taken together, RT could be regarded as a trigger of systemic antitumor immune response, and with the help of IO can be used as a radical and systemic treatment and be added into current standard regimen of patients with metastatic cancer.

Abscopal effect of radiation therapy and nivolumab in a patient with combined small-cell lung cancer: a case report

The paradigm for combined small-cell lung carcinoma (C-SCLC) is according to standard SCLC treatment with poor outcomes. The efficacy of immune checkpoint inhibitor (ICI) monotherapy for pretreated SCLC is still limited. Clinical researches exploring radiotherapy combined with immunotherapy showed promising synergistic effects in several tumors. We report one C-SCLC case after resistant to comprehensive treatment receiving nivolumab combined with radiotherapy achieving clinical complete remission (CCR). The combination module of ICI and radiation could be an option for relapsed C-SCLC, and the prognostic indicators need further research.

Mathematical modeling of radiotherapy and its impact on tumor interactions with the immune system

Radiotherapy is a primary therapeutic modality widely utilized with curative intent. Traditionally tumor response was hypothesized to be due to high levels of cell death induced by irreparable DNA damage. However, the immunomodulatory aspect of radiation is now widely accepted. As such, interest into the combination of radiotherapy and immunotherapy is increasing, the synergy of which has the potential to improve tumor regression beyond that observed after either treatment alone. However, questions regarding the timing (sequential vs concurrent) and dose fractionation (hyper-, standard-, or hypo-fractionation) that result in improved anti-tumor immune responses, and thus potentially enhanced tumor inhibition, remain. Here we discuss the biological response to radiotherapy and its immunomodulatory properties before giving an overview of pre-clinical data and clinical trials concerned with answering these questions. Finally, we review published mathematical models of the impact of radiotherapy on tumor-immune interactions. Ranging from considering the impact of properties of the tumor microenvironment on the induction of anti-tumor responses, to the impact of choice of radiation site in the setting of metastatic disease, these models all have an underlying feature in common: the push towards personalized therapy.

Tumour immunotherapy: lessons from predator-prey theory

With the burgeoning use of immune-based treatments for cancer, never has there been a greater need to understand the tumour microenvironment within which immune cells function and how it can be perturbed to inhibit tumour growth. Yet, current challenges in identifying optimal combinations of immunotherapies and engineering new cell-based therapies highlight the limitations of conventional paradigms for the study of the tumour microenvironment. Ecology has a rich history of studying predator-prey dynamics to discern factors that drive prey to extinction. Here, we describe the basic tenets of predator-prey theory as applied to 'predation' by immune cells and the 'extinction' of cancer cells. Our synthesis reveals fundamental mechanisms by which antitumour immunity might fail in sometimes counterintuitive ways and provides a fresh yet evidence-based framework to better understand and therapeutically target the immune-cancer interface.

Moving towards the Future of Radio-Immunotherapy: Could We “Tailor” the Abscopal Effect on Head and Neck Cancer Patients?

The abscopal effect (AbE) is defined as radiation-induced shrinkage of distant, non-treated, neoplastic lesions and it is considered the best clinical picture of the efficient immune stimulation by irradiation. The first report about abscopal tumor regression upon radiotherapy dates back to the beginning of the 20th century. The growing preclinical and clinical synergism between radiation and immunotherapy gave birth the purpose to more easily reproduce the abscopal effect, nevertheless, it is still rare in clinical practice. In this review we summarize immunological modulation of radiotherapy, focusing on the well-balanced equilibrium of tumor microenvironment and how radio-immunotherapy combinations can perturb it, with particular attention on head and neck squamous cell cancer. Finally, we investigate future perspectives, with the aim to “tailor” the abscopal effect to the patient.

Forecasting Individual Patient Response to Radiation Therapy in Head and Neck Cancer With a Dynamic Carrying Capacity Model

Purpose:

To model and predict individual patient responses to radiation therapy.

Methods and Materials:

We modeled tumor dynamics as logistic growth and the effect of radiation as a reduction in the tumor carrying capacity, motivated by the effect of radiation on the tumor microenvironment. The model was assessed on weekly tumor volume data collected for 2 independent cohorts of patients with head and neck cancer from the H. Lee Moffitt Cancer Center (MCC) and the MD Anderson Cancer Center (MDACC) who received 66 to 70 Gy in standard daily fractions or with accelerated fractionation. To predict response to radiation therapy for individual patients, we developed a new forecasting framework that combined the learned tumor growth rate and carrying capacity reduction fraction (δ) distribution with weekly measurements of tumor volume reduction for a given test patient to estimate δ, which was used to predict patient-specific outcomes.

Results:

The model fit data from MCC with high accuracy with patient-specific δ and a fixed tumor growth rate across all patients. The model fit data from an independent cohort from MDACC with comparable accuracy using the tumor growth rate learned from the MCC cohort, showing transferability of the growth rate. The forecasting framework predicted patient-specific outcomes with 76% sensitivity and 83% specificity for locoregional control and 68% sensitivity and 85% specificity for disease-free survival with the inclusion of 4 on-treatment tumor volume measurements.

Conclusions:

These results demonstrate that our simple mathematical model can describe a variety of tumor volume dynamics. Furthermore, combining historically observed patient responses with a few patient-specific tumor volume measurements allowed for the accurate prediction of patient outcomes, which may inform treatment adaptation and personalization.

Abscopal Effects in Metastatic Cancer: Is a Predictive Approach Possible to Improve Individual Outcomes?

Patients with metastatic cancers often require radiotherapy (RT) as a palliative therapy for cancer pain. RT can, however, also induce systemic antitumor effects outside of the irradiated field (abscopal effects) in various cancer entities. The occurrence of the abscopal effect is associated with a specific immunological activation in response to RT-induced cell death, which is mainly seen under concomitant immune checkpoint blockade. Even if the number of reported apscopal effects has increased since the introduction of immune checkpoint inhibition, its occurrence is still considered rare and unpredictable. The cases reported so far may nevertheless allow for identifying first biomarkers and clinical patterns. We here review biomarkers that may be helpful to predict the occurrence of abscopal effects and hence to optimize therapy for patients with metastatic cancers.

Tumor-immune ecosystem dynamics define an individual Radiation Immune Score to predict pan-cancer radiocurability

Radiotherapy efficacy is the result of radiation-mediated cytotoxicity coupled with stimulation of antitumor immune responses. We develop an in silico 3-dimensional agent-based model of diverse tumor-immune ecosystems (TIES) represented as anti- or pro-tumor immune phenotypes. We validate the model in 10,469 patients across 31 tumor types by demonstrating that clinically detected tumors have pro-tumor TIES. We then quantify the likelihood radiation induces antitumor TIES shifts toward immune-mediated tumor elimination by developing the individual Radiation Immune Score (iRIS). We show iRIS distribution across 31 tumor types is consistent with the clinical effectiveness of radiotherapy, and in combination with a molecular radiosensitivity index (RSI) combines to predict pan-cancer radiocurability. We show that iRIS correlates with local control and survival in a separate cohort of 59 lung cancer patients treated with radiation. In combination, iRIS and RSI predict radiation-induced TIES shifts in individual patients and identify candidates for radiation de-escalation and treatment escalation. This is the first clinically and biologically validated computational model to simulate and predict pan-cancer response and outcomes via the perturbation of the TIES by radiotherapy.

Mathematically modelling inflammation as a promoter of tumour growth

Inflammation is now known to play a significant role in tumour growth and progression. It is also difficult to adequately quantify systemic inflammation and the resulting localized effects in cancer. Here, we use experimental data to infer the possible contributions of inflammation in a mouse model of cancer. The model is validated by predicting tumour growth under anti-inflammatory treatments, and combination cancer therapies are explored. We then extend the model to consider simultaneous tumour implants at two distinct sites, which experimentally was shown to result in one large and one small tumour. We use this model to examine the role inflammation may play in the growth rate separation. Finally, we use this predictive two-tumour model to explore implications of inflammation on metastases, surgical removal of the primary and adjuvant anti-inflammatory treatments. This work suggests that improved tumour control can be obtained by targeting both the cancer and host, through anti-inflammatory treatments, including reduced metastatic burden post-surgical removal of primary tumours.

Circulating immune cell populations related to primary breast cancer, surgical removal, and radiotherapy revealed by flow cytometry analysis

BACKGROUND

Advanced breast cancer (BC) impact immune cells in the blood but whether such effects may reflect the presence of early BC and its therapeutic management remains elusive.

METHODS

To address this question, we used multiparametric flow cytometry to analyze circulating leukocytes in patients with early BC (n = 13) at the time of diagnosis, after surgery, and after adjuvant radiotherapy, compared to healthy individuals. Data were analyzed using a minimally supervised approach based on FlowSOM algorithm and validated manually.

RESULTS

At the time of diagnosis, BC patients have an increased frequency of CD117⁺CD11b⁺ granulocytes, which was significantly reduced after tumor removal. Adjuvant radiotherapy increased the frequency of CD45RO⁺ memory CD4⁺ T cells and CD4⁺ regulatory T cells. FlowSOM algorithm analysis revealed several unanticipated populations, including cells negative for all markers tested, CD11b⁺CD15^low, CD3⁺CD4^-CD8^-, CD3⁺CD4⁺CD8⁺, and CD3⁺CD8⁺CD127⁺CD45RO⁺ cells, associated with BC or radiotherapy.

CONCLUSIONS

This study revealed changes in blood leukocytes associated with primary BC, surgical removal, and adjuvant radiotherapy. Specifically, it identified increased levels of CD117⁺ granulocytes, memory, and regulatory CD4⁺ T cells as potential biomarkers of BC and radiotherapy, respectively. Importantly, the study demonstrates the value of unsupervised analysis of complex flow cytometry data to unravel new cell populations of potential clinical relevance.

An overview of the published and running randomized phase 3 clinical results of radiotherapy in combination with immunotherapy

Several studies have established that radiotherapy (RT) in combination with immunotherapy (IO) has a strong synergistic effect. RT changes the tumor microenvironment, generates local inflammation reactions, and enhances immunostimulatory effects, which are able to assist IO with improving local and systemic tumor control. In several pre-clinical reports, RT in combination with IO reveals regression of tumors locally (irradiated sites) and systemically (non-irradiated sites). Several clinical trials are currently running, mostly as phase I and II studies. This article provides an overview of the randomized, prospective reported and recruiting phase 3 clinical trials of RT in combination with IO. To date, three phase 3 trials have been published on RT and sequential IO with variable results, ranging from no significant difference (Kwon et al., START) to absolute differences in overall survival of 13.5% after 3 years (PACIFIC), respectively. No phase 3 randomized trials have been published on the simultaneous combination of RT with IO. Thirty trials are presently under way, and still recruiting patients to quantify the response to RT with IO. These studies fall into three categories of research interests: (I) to discover an enhancement effect of IO as induction therapy with RT; (II) to determine the additional effect of concurrent IO on the local effect of RT; and (III) to determine the additional effect of adjuvant or consolidation IO on the local effect of RT. Most of the ongoing studies are a combination of these interests, with 15 trials evaluating the concurrent RT+IO with IO consolidation strategy. The results in coming years will provide more insights in the role of RT as an activator of the immune system, the effect of IO as local sensitizer of RT, the optimal sequencing of IO with RT, and the total RT doses needed to obtain the optimal local and systemic effect.

The abscopal effect of radiation therapy

Radiation therapy (RT) in some cases results in a systemic anticancer response known as the abscopal effect. Multiple hypotheses support the role of immune activation initiated by RT-induced DNA damage. Optimal radiation dose is necessary to promote the cGAS-STING pathway in response to radiation and initiate an IFN-1 signaling cascade that promotes the maturation and migration of dendritic cells to facilitate antigen presentation and stimulation of cytotoxic T cells. T cells then exert a targeted response throughout the body at areas not subjected to RT. These effects are further augmented through the use of immunotherapeutic drugs resulting in increased T-cell activity. Tumor-infiltrating lymphocyte presence and TREX1, KPNA2 and p53 signal expression are being explored as prognostic biomarkers.

TP53 drives abscopal effect by secretion of senescence-associated molecular signals in non-small cell lung cancer

Background

Recent developments in abscopal effect strongly support the use of radiotherapy for the treatment of metastatic disease. However, deeper understanding of the molecular mechanisms underlying the abscopal effect are required to best benefit a larger proportion of patients with metastasis. Several groups including ours, reported the involvement of wild-type (wt) p53 in radiation-induced abscopal effects, however very little is known on the role of wtp53 dependent molecular mechanisms.

Methods

We investigated through in vivo and in vitro approaches how wtp53 orchestrates radiation-induced abscopal effects. Wtp53 bearing (A549) and p53-null (H1299) NSCLC lines were xenotransplanted in nude mice, and cultured in 2D monolayers and 3D tumor spheroids. Extracellular vesicles (EVs) were isolated from medium cell culture by ultracentrifugation protocol followed by Nanoparticle Tracking Analysis. Gene expression was evaluated by RT-Real Time, digital qRT-PCR, and dot blot technique. Protein levels were determined by immunohistochemistry, confocal anlysis, western blot techniques, and immunoassay.

Results

We demonstrated that single high-dose irradiation (20 Gy) induces significant tumor growth inhibition in contralateral non-irradiated (NIR) A549 xenograft tumors but not in NIR p53-null H1299 or p53-silenced A549 (A549sh/p53) xenografts. We further demonstrates that irradiation of A549 cells in vitro induces a senescence-associated secretory phenotype (SASP) producing extracellular vesicles (EVs) expressing CD63 and carrying DNA:RNA hybrids and LINE-1 retrotransposon. IR-A549 EVs also hamper the colony-forming capability of recipient NIR A549 cells, induce senescent phenotype, nuclear expression of DNA:RNA hybrids, and M1 macrophage polarization.

Conclusions

In our models, we demonstrate that high radiation dose in wtp53 tumors induce the onset of SASP and secretion of CD63+ EVs loaded with DNA:RNA hybrids and LINE-1 retrotransposons that convey senescence messages out of the irradiation field triggering abscopal effect in NIR tumors.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01883-0.

Parameter perturbations in a post-treatment chronic myeloid leukemia model capture the essence of pre-diagnosis A-bomb survivor mysteries

A model of post-diagnosis chronic myeloid leukemia (CML) dynamics across treatment cessations is applied here to pre-diagnosis scenarios of A-bomb survivors. The main result is that perturbing two parameters of a two-state simplification of this model captures the essence of two A-bomb survivor mysteries: (1) in those exposed to > 1 Sv in Hiroshima, four of six female onsets arose as a cluster in 1969-1974, well after 5-10-year latencies expected and observed in two of six female- and nine of ten male cases (about one background case was expected in this high-dose cohort); and (2) no Nagasaki adult cases exposed to > 0.2 Sv were observed though about nine were expected (~ 1.5 background +  ~ 7.5 radiation-induced). Overall, it is concluded that: (1) whole-body radiation co-creates malignant and benign BCR-ABL clones; (2) benign clones are more likely to act as anti-CML vaccines in females than in males; (3) the Hong Kong flu of 1968 (and H3N2 seasonal flu thereafter) exhausted anti-CML immunity, thereby releasing radiation-induced clones latent in high-dose Hiroshima females; and (4) benign cells of 1-2 are CD4⁺ as human T-cell leukemia-lymphoma virus-1 endemic to Nagasaki but not Hiroshima expands numbers of such cells. The next goal is to see if these conclusions can be substantiated using banked A-bomb survivor blood samples.

Quantifying the limits of CAR T-cell delivery in mice and men

CAR (Chimeric Antigen Receptor) T cells have demonstrated clinical success for the treatment of multiple lymphomas and leukaemias, but not for various solid tumours, despite promising data from murine models. Lower effective CAR T-cell delivery rates to human solid tumours compared to haematological malignancies in humans and solid tumours in mice might partially explain these divergent outcomes. We used anatomical and physiological data for human and rodent circulatory systems to calculate the typical perfusion of healthy and tumour tissues, and estimated the upper limits of immune cell delivery rates across different organs, tumour types and species. Estimated maximum delivery rates were up to 10 000-fold greater in mice than humans yet reported CAR T-cell doses are typically only 10-100-fold lower in mice, suggesting that the effective delivery rates of CAR T cells into tumours in clinical trials are far lower than in corresponding mouse models. Estimated delivery rates were found to be consistent with published positron emission tomography data. Results suggest that higher effective human doses may be needed to drive efficacy comparable to mouse solid tumour models, and that lower doses should be tested in mice. We posit that quantitation of species and organ-specific delivery and homing of engineered T cells will be key to unlocking their potential for solid tumours.

Education and Outreach in Physical Sciences in Oncology

Physical sciences are often overlooked in the field of cancer research. The Physical Sciences in Oncology Initiative was launched to integrate physics, mathematics, chemistry, and engineering with cancer research and clinical oncology through education, outreach, and collaboration. Here, we provide a framework for education and outreach in emerging transdisciplinary fields.

Evidence for Early Stage Anti-Tumor Immunity Elicited by Spatially Fractionated Radiotherapy-Immunotherapy Combinations

The combination of radiotherapy and immunotherapy may generate synergistic anti-tumor host immune responses and promote abscopal effects. Spatial fractionation of a radiation dose has been found to promote unique physiological responses of tumors, which might promote synergy with immunotherapy. To determine whether spatial fractionation may augment immune activity, whole-tumor or spatial fractionation grid radiation treatment (GRID) alone or in combination with antibodies against immune checkpoints PD1 and CTLA-4 were tested in an immunocompetent mouse model using a triple negative breast tumor (4T1). Tumor growth delay, immunohistochemistry and flow cytometry were used to characterize the effects of each treatment type. Whole-beam radiation with immune checkpoint inhibition significantly restrained tumor growth in the irradiated tumor, but not abscopal tumors, compared to either of these treatments alone. In mice that received spatially fractionated irradiation, evidence of abscopal immune responses were observed in contralateral tumors with markedly enhanced infiltration of both antigen-presenting cells and activated T cells, which were preceded by increased systemic IFNγ production and led to eventual tumor growth delay. These studies suggest that systemic immune activation may be triggered by employing GRID to a primary tumor lesion, promoting anti-tumor immune responses outside the treatment field. Interestingly, PD-L1 was found to be upregulated in abscopal tumors from GRID-treated mice. Combined radio-immunotherapy therapy is becoming a validated and novel approach in the treatment of cancer. With the potential increased benefit of GRID to augment both local and metastatic disease responses, further exploration of GRID treatment as a part of current standards of care is warranted.

Radiotherapy and Immunotherapy Combinations for Lung Cancer

PURPOSE OF REVIEW

Positive results from recent immunotherapy trials of non-small cell lung cancer (NSCLC) have coincided with a greater appreciation for the impact of radiation therapy (RT) on tumor immunity. Here, we summarize key clinical findings and ongoing efforts to combine immunotherapy and RT for the treatment of NSCLC.

RECENT FINDINGS

The role of immunotherapy for NSCLC has expanded significantly following the pivotal approvals of nivolumab and pembrolizumab for metastatic NSCLC, maintenance durvalumab in unresectable stage III NSCLC, and atezolizumab for metastatic NSCLC. Several small early-phase trials have demonstrated the ability of RT to elicit clinically significant tumor immunity. These positive findings support current trial efforts combining RT with immunotherapy for NSCLC. Recently initiated trials of RT and immunotherapy hold significant promise in expanding the therapeutic options for NSCLC. Optimization of therapy will require careful patient selection to yield meaningful improvements in clinical outcomes.

Exosomes and exosomal microRNA in non-targeted radiation bystander and abscopal effects in the central nervous system

Localized cranial radiotherapy is a dominant treatment for brain cancers. After being subjected to radiation, the central nervous system (CNS) exhibits targeted effects as well as non-targeted radiation bystander effects (RIBE) and abscopal effects (RIAE). Radiation-induced targeted effects in the CNS include autophagy and various changes in tumor cells due to radiation sensitivity, which can be regulated by microRNAs. Non-targeted radiation effects are mainly induced by gap junctional communication between cells, exosomes containing microRNAs can be transduced by intracellular endocytosis to regulate RIBE and RIAE. In this review, we discuss the involvement of microRNAs in radiation-induced targeted effects, as well as exosomes and/or exosomal microRNAs in non-targeted radiation effects in the CNS. As a target pathway, we also discuss the Akt pathway which is regulated by microRNAs, exosomes, and/or exosomal microRNAs in radiation-induced targeted effects and RIBE in CNS tumor cells. As the CNS-derived exosomes can cross the blood-brain-barrier (BBB) into the bloodstream and be isolated from peripheral blood, exosomes and exosomal microRNAs can emerge as promising minimally invasive biomarkers and therapeutic targets for radiation-induced targeted and non-targeted effects in the CNS.

A review of radiation induced abscopal effect: combining radiotherapy and immunotherapy to treat the untreated distant metastatic tumours

Background:

Radiotherapy is an effective and significant mode of definitive cancer treatment with well-established local tumour control success, especially in the treatment of localised tumours. Although, for metastatic disease, the role of radiotherapy has generally been limited to palliation of symptoms. In the treatment of metastatic diseases settings, the radiation therapy technique has always been confronted with the challenge of the simultaneous treatment of all of the various distant metastatic tumour sites, however, some recent evidence suggests that radiotherapy can potentially induce anticancer immune responses whose effectors potentially migrate to distant metastatic tumours to provoke their regression in cancer patients. Thus, unirradiated distant metastatic tumour sites can exhibit a delayed therapeutic response termed the abscopal effect.

Materials and methods:

This paper reports on a review of the abscopal effect, including its biological mechanism, the effect of radiation dose and fractionation regime and the timing of immunotherapy administration on radiotherapy-induced abscopal effect, the enhancement of radiotherapy-induced abscopal effects with immunotherapy, the effect of the location of the irradiated tumour and the radiotherapy of multiple tumour sites on the likelihood and effectiveness of inducing abscopal responses in the preclinical and clinical settings and also reports on some evidence of clinical observations in patients.

Conclusions:

Although abscopal effects of radiotherapy are still relatively rare in patients, it has gained a lot of interest due to recent development and use of immunotherapy strategies incorporating combinations of targeted immunomodulators and immune checkpoint blockade with radiation therapy. The enhancement of cancer immunotherapy could potentially enable the translation of the concept of abscopal effect into the clinics as a new strategy to induce therapeutically effective anti-tumour immune responses in cancer patients. The combination of radiotherapy and immunotherapy has the potential to expand the role of radiotherapy from a purely local tumour control treatment to play a significant role in advanced and metastatic tumour control and this could likely lead to a paradigm shift in the treatment of patients with metastatic cancer.

Implications of immune-mediated metastatic growth on metastatic dormancy, blow-up, early detection, and treatment

Metastatic seeding of distant organs can occur in the very early stages of primary tumor development. Once seeded, these micrometastases may enter a dormant phase that can last decades. Curiously, the surgical removal of the primary tumor can stimulate the accelerated growth of distant metastases, a phenomenon known as metastatic blow-up. Recent clinical evidence has shown that the immune response can have strong tumor promoting effects. In this work, we investigate if the pro-tumor effects of the immune response can have a significant contribution to metastatic dormancy and metastatic blow-up. We develop an ordinary differential equation model of the immune-mediated theory of metastasis. We include both anti- and pro-tumor immune effects, in addition to the experimentally observed phenomenon of tumor-induced immune cell phenotypic plasticity. Using geometric singular perturbation analysis, we derive a rather simple model that captures the main processes and, at the same time, can be fully analyzed. Literature-derived parameter estimates are obtained, and model robustness is demonstrated through a time dependent sensitivity analysis. We determine conditions under which the parameterized model can successfully explain both metastatic dormancy and blow-up. The results confirm the significant active role of the immune system in the metastatic process. Numerical simulations suggest a novel measure to predict the occurrence of future metastatic blow-up in addition to new potential avenues for treatment of clinically undetectable micrometastases.

Research Progress and Existing Problems for Abscopal Effect

Radiation therapy plays a vital role in the treatment of tumours. In particular, the occurrence of the “abscopal effect” brings about a favourable turn for the treatment of patients with advanced metastatic malignant tumours. Because of the abscopal effect, non-irradiated areas are also treated. However, the abscopal effect occurs by chance, not through seeking. Although the abscopal effect has been studied enthusiastically, the desired result does not appear to be achieved. Moreover, its combination with immunotherapy appears to be overwhelming. There is an opinion that abscopal effect is difficult to achieve by irradiation of a single tumour, and irradiation of multiple or total lesions is advocated to increase the possibility of obtaining clinically meaningful outcomes. Obviously, there are still questions about the mechanism, condition and possibility underlying the occurrence of the abscopal effect. Can the abscopal effect truly change the future treatment strategy as the researchers expect? What are the current problems? This article reviewed the research in recent years to explore the progress and controversy surrounding the abscopal effect of radiation therapy.

Synergies of Antiangiogenic Therapy and Immune Checkpoint Blockade in Renal Cell Carcinoma: From Theoretical Background to Clinical Reality

The hallmarks of renal cell carcinoma (RCC) are angiogenesis and immunogenic tumor microenvironment. Over the past decades, treatment options for metastatic RCC (mRCC) have been expanding, from the inhibition of vessel formation via antiangiogenic agents (AAs) to the stimulation of immune system by immune checkpoint inhibitors (ICIs). Since 2005, the introduction of antiangiogenic agents targeting vascular endothelial growth factor (VEGF), its receptors (VEGFRs), and mammalian target of rapamycin (mTOR) pathway have experienced moderate success in the therapeutics of mRCC, but patient outcomes remain suboptimal. Recently, the development of ICIs targeting cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and the programmed death-1/programmed death ligand 1 (PD-1/PD-L1) pathways has dramatically changed the treatment landscape of mRCC. Expressly, the combination of ipilimumab and nivolumab has been confirmed to improve clinical outcomes and approved as a standard care for intermediate- or poor-risk mRCC patients. Nevertheless, innate or adaptive drug resistance is observed within both treatment approaches, limiting overall clinical benefit. This phenomenon will underscore the urgent need for new combinational therapy strategies with different mechanisms of action, which can improve efficacy in an extended patient population without severe toxic effects. In 2019, as the results of two critical phase III trials came to light, FDA approved axitinib plus avelumab, or pembrolizumab as first-line standard management for mRCC, which cements the combination of AAs plus ICIs and advances the mRCC treatment field. This review summarizes current evidence on the interplay and synergies between AAs and immunomodulating drugs in mRCC, focusing on the theoretical background and the status of current clinical development.

Anchoring of intratumorally administered cytokines to collagen safely potentiates systemic cancer immunotherapy

The clinical application of cytokine therapies for cancer treatment remains limited due to severe adverse reactions and insufficient therapeutic effects. Although cytokine localization by intratumoral administration could address both issues, the rapid escape of soluble cytokines from the tumor invariably subverts this effort. We find that intratumoral administration of a cytokine fused to the collagen-binding protein lumican prolongs local retention and markedly reduces systemic exposure. Combining local administration of lumican-cytokine fusions with systemic immunotherapies (tumor-targeting antibody, checkpoint blockade, cancer vaccine, or T cell therapy) improves efficacy without exacerbating toxicity in syngeneic tumor models and the Braf^V600E /Pten^fl/fl genetically engineered melanoma model. Curative abscopal effects on noncytokine-injected tumors were also observed as a result of a protective and systemic CD8⁺ T cell response primed by local therapy. Cytokine collagen-anchoring constitutes a facile, tumor-agnostic strategy to safely potentiate otherwise marginally effective systemic immunotherapies.

A tumor-immune interaction model for hepatocellular carcinoma based on measured lymphocyte counts in patients undergoing radiotherapy

PURPOSE

The impact of radiation therapy on the immune system has recently gained attention particularly when delivered in combination with immunotherapy. However, it is unclear how different treatment fractionation regimens influence the interaction between the immune system and radiation. The goal of this work was to develop a mathematical model that quantifies both the immune stimulating as well as the immunosuppressive effects of radiotherapy and simulates the effects of different fractionation regimens based on patient data.

METHODS AND MATERIALS

The framework describes the temporal evolution of tumor cells, lymphocytes, and inactivated dying tumor cells releasing antigens during radiation therapy, specifically modeling how recruited lymphocytes inhibit tumor progression. The parameters of the model were partly taken from the literature and in part extracted from blood samples (circulating lymphocytes: CLs) collected from hepatocellular carcinoma patients undergoing radiotherapy and their outcomes. The dose volume histograms to circulating lymphocytes were calculated with a probability-based model.

RESULTS

Based on the fitted parameters, the model enabled a study into the depletion and recovery of CLs in patients as a function of fractionation regimen. Our results quantify the ability of short fractionation regimens to lead to shorter periods of lymphocyte depletion and predict faster recovery after the end of treatment. The model shows that treatment breaks between fractions can prolong the period of lymphocyte depletion and should be avoided.

CONCLUSIONS

This study introduces a mathematical model for tumor-immune interactions using clinically extracted radiotherapy patient data, which can be applied to design trials aimed at minimizing lymphocyte depleting effects in radiation therapy.

The Immune Checkpoint Kick Start: Optimization of Neoadjuvant Combination Therapy Using Game Theory

PURPOSE

In an upcoming clinical trial at the Moffitt Cancer Center for women with stage 2/3 estrogen receptor-positive breast cancer, treatment with an aromatase inhibitor and a PD-L1 checkpoint inhibitor combination will be investigated to lower a preoperative endocrine prognostic index (PEPI) that correlates with relapse-free survival. PEPI is fundamentally a static index, measured at the end of neoadjuvant therapy before surgery. We have developed a mathematical model of the essential components of the PEPI score to identify successful combination therapy regimens that minimize tumor burden and metastatic potential, on the basis of time-dependent trade-offs in the system.

METHODS

We considered two molecular traits, CCR7 and PD-L1, which correlate with treatment response and increased metastatic risk. We used a matrix game model with the four phenotypic strategies to examine the frequency-dependent interactions of cancer cells. This game was embedded in an ecological model of tumor population-growth dynamics. The resulting model predicts evolutionary and ecological dynamics that track with changes in the PEPI score.

RESULTS

We considered various treatment regimens on the basis of combinations of the two therapies with drug holidays. By considering the trade off between tumor burden and metastatic potential, the optimal therapy plan was a 1-month kick start of the immune checkpoint inhibitor followed by 5 months of continuous combination therapy. Relative to a protocol giving both therapeutics together from the start, this delayed regimen resulted in transient suboptimal tumor regression while maintaining a phenotypic constitution that is more amenable to fast tumor regression for the final 5 months of therapy.

CONCLUSION

The mathematical model provides a useful abstraction of clinical intuition, enabling hypothesis generation and testing of clinical assumptions.

Immunologic Consequences of Sequencing Cancer Radiotherapy and Surgery

PURPOSE

Early-stage cancers are routinely treated with surgery followed by radiotherapy (SR). Radiotherapy before surgery (RS) has been widely ignored for some cancers. We evaluate overall survival (OS) and disease-free survival (DFS) with SR and RS for different cancer types and simulate the plausibility of RS- and SR-induced antitumor immunity contributing to outcomes.

MATERIALS AND METHODS

We analyzed a SEER data set of early-stage cancers treated with SR or RS. OS and DFS were calculated for cancers with sufficient numbers for statistical power (cancers of lung and bronchus, esophagus, rectum, cervix uteri, corpus uteri, and breast). We simulated the immunologic consequences of SR, RS, and radiotherapy alone in a mathematical model of tumor-immune interactions.

RESULTS

RS improved OS for cancers with low 20-year survival rates (lung: hazard ratio [HR], 0.88; P = .046) and improved DFS for cancers with higher survival (breast: HR = 0.64; P < .001). For rectal cancer, with intermediate 20-year survival, RS improved both OS (HR = 0.89; P = .006) and DFS (HR = 0.86; P = .04). Model simulations suggested that RS could increase OS by eliminating cancer for a broader range of model parameters and radiotherapy-induced antitumor immunity compared with SR for selected parameter combinations. This could create an immune memory that may explain increased DFS after RS for certain cancers.

CONCLUSION

Study results suggest plausibility that radiation to the bulk of the tumor could induce a more robust immune response and better harness the synergy of radiotherapy and antitumor immunity than postsurgical radiation to the tumor bed. This exploratory study provides motivation for prospective evaluation of immune activation of RS versus SR in controlled clinical studies.

Blood Flow Contributions to Cancer Metastasis

The distribution patterns of cancer metastasis depend on a sequence of steps involving adhesion molecules and on mechanical and geometrical effects related to blood circulation, but how much each of these two aspects contributes to the metastatic spread of a specific tumor is still unknown. Here we address this question by simulating cancer cell trajectories in a high-resolution humanoid model of global blood circulation, including stochastic adhesion events, and comparing the results with the location of metastasis recorded in thousands of human autopsies for seven different solid tumors, including lung, prostate, pancreatic and colorectal cancers, showing that on average 40% of the variation in the metastatic distribution can be attributed to blood circulation. Our humanoid model of circulating tumor cells allows us to predict the metastatic spread in specific realistic conditions and can therefore guide precise therapeutic interventions to fight metastasis.

Abscopal effect induced by modulated radiation therapy and pembrolizumab in a patient with pancreatic metastatic lung squamous cell carcinoma

The main recurrence pattern for lung cancer patients after radical surgery is distant metastasis. The probability of pancreatic metastasis in patients diagnosed with lung squamous cell carcinoma is 0.02%, with a poor prognosis. Chemotherapy is the preferred treatment for recurrence. Single lesions or oligometastasis can be surgically resected, and local lesions with compression symptoms can be treated with radiotherapy. The FDA and NMPA have approved first‐line indications for immunotherapy for lung squamous cell carcinoma. Here, we report the case of a 57‐year‐old male patient with lung squamous cell carcinoma who developed pancreatic metastasis after radical resection. The disease progressed after first‐line chemotherapy, and the patient was treated with immunotherapy combined with radiotherapy. We subsequently observed the abscopal effect of intensity modulated radiation therapy (IMRT) and pembrolizumab with disappearance of lung metastasis after radiotherapy for pancreatic metastasis. The patient’s tumor symptoms were relieved with prolonged survival.

On the Immunological Consequences of Conventionally Fractionated Radiotherapy

Emerging evidence demonstrates that radiotherapy induces immunogenic death on tumor cells that emit immunostimulating signals resulting in tumor-specific immune responses. However, the impact of tumor features and microenvironmental factors on the efficacy of radiation-induced immunity remains to be elucidated. Herein, we use a calibrated model of tumor-effector cell interactions to investigate the potential benefits and immunological consequences of radiotherapy. Simulations analysis suggests that radiotherapy success depends on the functional tumor vascularity extent and reveals that the pre-treatment tumor size is not a consistent determinant of treatment outcomes. The one-size-fits-all approach of conventionally fractionated radiotherapy is predicted to result in some overtreated patients. In addition, model simulations also suggest that an arbitrary increase in treatment duration does not necessarily result in better tumor control. This study highlights the potential benefits of tumor-immune ecosystem profiling during treatment planning to better harness the immunogenic potential of radiotherapy.

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Radiotherapy success depends on radiation-induced tumor-specific immune responses

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Pre-treatment tumor size is not a consistent determinant of radiotherapy outcomes

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Increase in treatment duration does not necessarily result in better tumor control

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Tumor vascularity impacts antitumor efficacy of radiation-induced immune responses

A minimal modeling framework of radiation and immune system synergy to assist radiotherapy planning

Recent evidence indicates the ability of radiotherapy to induce local and systemic tumor-specific immune responses as a result of immunogenic cell death. However, fractionation regimes routinely used in clinical practice typically ignore the synergy between radiation and the immune system, and instead attempt to completely eradicate tumors by the direct lethal effect of radiation on cancer cells. This paradigm is expected to change in the near future due to the potential benefits of considering radiation-induced antitumor immunity during treatment planning. Towards this goal, we propose a minimal modeling framework based on key aspects of the tumor-immune system interplay to simulate the effects of radiation on tumors and the immunological consequences of radiotherapy. The impacts of tumor-associated vasculature and intratumoral oxygen-mediated heterogeneity on treatment outcomes are ininvestigated. The model provides estimates of the minimum radiation doses required for tumor eradication given a certain number of treatment fractions. Moreover, estimates of treatment duration for disease control given predetermined fractional radiation doses can be also obtained. Although theoretical in nature, this study motivates the development and establishment of immune-based decision-support tools in radiotherapy planning.

Checkpoint inhibitor immunotherapy in kidney cancer

Kidney cancer has unique features that make this malignancy attractive for therapeutic approaches that target components of the immune system. Immune checkpoint inhibition is a well-established part of kidney cancer treatment, and rapid advances continue to be made in this field. Initial preclinical studies that elucidated the biology of the programmed cell death 1 (PD-1), programmed cell death 1 ligand 1 (PD-L1) and cytotoxic T lymphocyte antigen 4 (CTLA-4) immune checkpoints led to a series of clinical trials that resulted in regulatory approval of nivolumab and the combination of ipilimumab plus nivolumab for the treatment of advanced renal cell carcinoma. Subsequent data led to approvals of combination strategies of immune checkpoint inhibition plus agents that target the vascular endothelial growth factor receptor and a shift in the current standard of renal cell carcinoma care. However, controversies remain regarding the optimal therapy selection and treatment strategy for individual patients, which might be eventually overcome by current intensive efforts in biomarker research. That work includes evaluation of tumour cell PD-L1 expression, gene expression signatures, CD8⁺ T cell density and others. In the future, further advances in the understanding of immune checkpoint biology might reveal new therapeutic targets beyond PD-1, PD-L1 and CTLA-4, as well as new combination approaches.

The evolving use of pembrolizumab in combination treatment approaches for non-small cell lung cancer

Introduction: The immune checkpoint inhibitor, pembrolizumab, has revolutionized the treatment of non-small cell lung cancer (NSCLC). It is currently approved and widely used in patients with advanced NSCLC whose tumors have no EGFR or ALK genomic aberrations that express PD-L1 as single-agent treatment and irrespective of PD-L1 expression in combination with platinum-based doublet chemotherapy in the first-line setting.Areas covered: The authors have reviewed articles discussing pembrolizumab and NSCLC in MEDLINE between July 2013 to August 2019 and focus on recent advances in combining pembrolizumab with chemotherapy, radiotherapy and other novel agents in various stages of NSCLC.Expert opinion: Although pembrolizumab has revolutionized the treatment of advanced NSCLC, only a subset of patients benefit from single-agent therapy. Numerous trials combining pembrolizumab with chemotherapy and radiation have shown benefit and a large spectrum of novel combination strategies are being explored for improved synergies. In addition to PD-L1 tumor proportion score, validation of other biomarkers would be beneficial in stratifying patients and improving the predictive value of combining immune check point inhibitors and chemotherapy.

A mathematical model for the immune-mediated theory of metastasis

Accumulating experimental and clinical evidence suggest that the immune response to cancer is not exclusively anti-tumor. Indeed, the pro-tumor roles of the immune system  -  as suppliers of growth and pro-angiogenic factors or defenses against cytotoxic immune attacks, for example  -  have been long appreciated, but relatively few theoretical works have considered their effects. Inspired by the recently proposed "immune-mediated" theory of metastasis, we develop a mathematical model for tumor-immune interactions at two anatomically distant sites, which includes both anti- and pro-tumor immune effects, and the experimentally observed tumor-induced phenotypic plasticity of immune cells (tumor "education" of the immune cells). Upon confrontation of our model to experimental data, we use it to evaluate the implications of the immune-mediated theory of metastasis. We find that tumor education of immune cells may explain the relatively poor performance of immunotherapies, and that many metastatic phenomena, including metastatic blow-up, dormancy, and metastasis to sites of injury, can be explained by the immune-mediated theory of metastasis. Our results suggest that further work is warranted to fully elucidate the pro-tumor effects of the immune system in metastatic cancer.