Enhancing the efficacy of radiation therapy: premises, promises, and practicality

Analysis of prognostic factors of undifferentiated pleomorphic sarcoma and construction and validation of a prediction nomogram based on SEER database

Background

Undifferentiated pleomorphic sarcoma (UPS) is considered one of the most common types of soft tissue sarcoma (STS). Current studies have shown that the prognosis of UPS is related to some of its clinical characteristics, but no survival prediction model for the overall survival (OS) of UPS patients has been reported. The purpose of this study is to construct and validate a nomogram for predicting OS in UPS patients at 3, 5 years after the diagnosis.

Methods

According to the inclusion and exclusion criteria, 1079 patients with UPS were screened from the SEER database and randomly divided into the training cohort (n = 755) and the validation cohort (n = 324). Patient demographic and clinicopathological characteristics were first described, and the correlation between the two groups was compared, using the Kaplan–Meier method and Cox regression analysis to determine independent prognostic factors. Based on the identified independent prognostic factors, a nomogram for OS in UPS patients was established using R language. The nomogram’s performance was then validated using multiple indicators, including the area under the receiver operating characteristic curve (AUC), consistency index (C-index), calibration curve, and decision curve analysis (DCA).

Results

Both the C-index of the OS nomogram in the training cohort and the validation cohort were greater than 0 .75, and both the values of AUC were greater than 0.78. These four values were higher than their corresponding values in the TNM staging system, respectively. The calibration curves of the Nomogram prediction model and the TNM staging system were well fitted with the 45° line. Decision curve analysis showed that both the nomogram model and the TNM staging system had clinical net benefits over a wide range of threshold probabilities, and the nomogram had higher clinical net benefits than the TNM staging system as a whole.

Conclusion

With good discrimination, accuracy, and clinical practicability, the nomogram can individualize the prediction of 3-year and 5-year OS in patients with UPS, which can provide a reference for clinicians and patients to make better clinical decisions.

Bioengineered nanogels for cancer immunotherapy

Recent years have witnessed increasingly rapid advances in nanocarrier-based biomedicine aimed at improving treatment paradigms for cancer. Nanogels serve as multipurpose and constructed vectors formed via intramolecular cross-linking to generate drug delivery systems, which is attributed predominantly to their satisfactory biocompatibility, bio-responsiveness, high stability, and low toxicity. Recently, immunotherapy has experienced unprecedented growth and has become the preferred strategy for cancer treatment, and mainly involves the mobilisation of the immune system and an enhanced anti-tumour immunity of the tumour microenvironment. Despite the inspiring success, immunotherapeutic strategies are limited due to the low response rates and immune-related adverse events. Like other nanomedicines, nanogels are comparably limited by lower focal enrichment rates upon introduction into the organism via injection. Because nanogels are three-dimensional cross-linked aqueous materials that exhibit similar properties to natural tissues and are structurally stable, they can comfortably cope with shear forces and serum proteins in the bloodstream, and the longer circulation life increases the chance of nanogel accumulation in the tumour, conferring deep tumour penetration. The large specific surface area can reduce or eliminate off-target effects by introducing stimuli-responsive functional groups, allowing multiple physical and chemical modifications for specific purposes to improve targeting to specific immune cell subpopulations or immune organs, increasing the bioavailability of the drug, and conferring a low immune-related adverse events on nanogel therapies. The slow release upon reaching the tumour site facilitates long-term awakening of the host's immune system, ultimately achieving enhanced therapeutic effects. As an effective candidate for cancer immunotherapy, nanogel-based immunotherapy has been widely used. In this review, we mainly summarize the recent advances of nanogel-based immunotherapy to deliver immunomodulatory small molecule drugs, antibodies, genes and cytokines, to target antigen presenting cells, form cancer vaccines, and enable chimeric antigen receptor (CAR)-T cell therapy. Future challenges as well as expected and feasible prospects for clinical treatment are also highlighted.

Radiation therapy and molecular-targeted agents in preclinical testing for immunotherapy, brain tumors, and sarcomas: Opportunities and challenges

Despite radiation therapy (RT) being an integral part of the treatment of most pediatric cancers and the recent discovery of novel molecular-targeted agents (MTAs) in this era of precision medicine with the potential to improve the therapeutic ratio of modern chemoradiotherapy regimens, there are only a few preclinical trials being conducted to discover novel radiosensitizers and radioprotectors. This has resulted in a paucity of translational clinical trials combining RT and novel MTAs. This report describes the opportunities and challenges of investigating RT together with MTAs in preclinical testing for immunotherapy, brain tumors, and sarcomas in pediatric oncology. We discuss the need for improving the collaboration between radiation oncologists, biologists, and physicists to improve the reliability, reproducibility, and translational potential of RT-based preclinical research. Current translational clinical trials using RT and MTAs for immunotherapy, brain tumors, and sarcomas are described. The technologic advances in experimental RT, availability of novel experimental tumor models, advances in immunology and tumor biology, and the discovery of novel MTAs together hold considerable promise for good quality preclinical and clinical multimodality research to improve the current rates of survival and toxicity in children afflicted with cancer.

Cascade-amplification of therapeutic efficacy: An emerging opportunity in cancer treatment

Increasing research evidence reveals that cancer is complex disease involving many biological factors, processes and systems, which may severely limit the actual efficacy of conventional monotonic anticancer approaches. To overcome these obstacles in cancer treatment, a new strategy has been proposed by combining multiple synergistic therapeutic modalities accessing different but inherently related targets and acting sequentially. A major benefit of this strategy is that the multi-target mechanism could result in a cascade-amplification effect leading to enhanced anticancer activity. In this review, we provide a critical discussion on the application of cascade-amplification strategy in the treatment of various cancer indications, focusing on the rational combination of therapeutic agents and their mechanisms of action. A concise yet comprehensive analysis on the potential therapeutic benefit of this strategy was also included. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Ablative stereotactic radiotherapy for oligometastatic colorectal cancer: Systematic review

BACKGROUND

SBRT is a novel modality in treatment for oligometastatic colorectal cancer. We aimed to perform a systematic review of results of SBRT in maintaining LC (local control) for CRC liver and lung oligometastases.

MATERIALS AND METHODS

The review was performed according to PRISMA and PICO guidelines. Database search using keywords: stereotactic, colon, colorectal, cancer, sbrt, sabr returned 457 results. 15 were included in the study. Only cohorts with CRC histology and reported LC were included.

RESULTS

For liver LC rates ranged from 50% to 100% after 1 year and 32% to 91% after 2 years. BED range 40.5-262.5 Gy (Gray). For lung LC rates ranged from 62% to 92% after 1 one year and from 53% to 92% after 2 years. BED range 51.3-262.5 Gy.

CONCLUSIONS

SBRT of oligometastatic CRC offers high LC with low morbidity and toxicity. It requires more observational studies and randomized trials but available data on clinical efficacy is promising, however not yet matured.

Radiotherapy: Changing the Game in Immunotherapy

Immune checkpoint inhibitors are effective in cancer treatment. A pre-existing immune response demonstrated by significant pretreatment tumor lymphocytic infiltration is a pre-requisite for response. Within such infiltrated tumors, referred as "hot", immune checkpoint inhibitors rescue anti-tumor T cells activity. In contrast, "cold" tumors lack lymphocytic infiltration and are refractory to immunotherapy. Preclinical data show that radiotherapy sensitizes refractory tumors to immune checkpoint inhibitors by recruiting anti-tumor T cells. Despite the growing number of clinical studies testing radiation's ability to enhance immunotherapy, clinical evidence that it converts cold tumors into responsive ones remains elusive. Here we review evidence that radiotherapy is not only an occasional enhancer of immunotherapy's effects but a "game changer", and propose a blueprint to test this.

Computer aided prognosis for cell death categorization and prediction in vivo using quantitative ultrasound and machine learning techniques

PURPOSE

At present, a one-size-fits-all approach is typically used for cancer therapy in patients. This is mainly because there is no current imaging-based clinical standard for the early assessment and monitoring of cancer treatment response. Here, the authors have developed, for the first time, a complete computer-aided-prognosis (CAP) system based on multiparametric quantitative ultrasound (QUS) spectroscopy methods in association with texture descriptors and advanced machine learning techniques. This system was used to noninvasively categorize and predict cell death levels in fibrosarcoma mouse tumors treated using ultrasound-stimulated microbubbles as novel endothelial-cell radiosensitizers.

METHODS

Sarcoma xenograft tumor-bearing mice were treated using ultrasound-stimulated microbubbles, alone or in combination with x-ray radiation therapy, as a new antivascular treatment. Therapy effects were assessed at 2-3, 24, and 72 h after treatment using a high-frequency ultrasound. Two-dimensional spectral parametric maps were generated using the power spectra of the raw radiofrequency echo signal. Subsequently, the distances between "pretreatment" and "post-treatment" scans were computed as an indication of treatment efficacy, using a kernel-based metric on textural features extracted from 2D parametric maps. A supervised learning paradigm was used to either categorize cell death levels as low, medium, or high using a classifier, or to "continuously" predict the levels of cell death using a regressor.

RESULTS

The developed CAP system performed at a high level for the classification of cell death levels. The area under curve of the receiver operating characteristic was 0.87 for the classification of cell death levels to both low/medium and medium/high levels. Moreover, the prediction of cell death levels using the proposed CAP system achieved a good correlation (r = 0.68,  p < 0.001) with histological cell death levels as the ground truth. A statistical test of significance between individual treatment groups with the corresponding control group demonstrated that the predicted levels indicated the same significant changes in cell death as those indicated by the ground-truth levels.

CONCLUSIONS

The technology developed in this study addresses a gap in the current standard of care by introducing a quality control step that generates potentially actionable metrics needed to enhance treatment decision-making. The study establishes a noninvasive framework for quantifying levels of cancer treatment response developed preclinically in tumors using QUS imaging in conjunction with machine learning techniques. The framework can potentially facilitate the detection of refractory responses in patients to a certain cancer treatment early on in the course of therapy to enable switching to more efficacious treatments.

Radiation Therapy for Soft Tissue Sarcoma: Indications and Controversies for Neoadjuvant Therapy, Adjuvant Therapy, Intraoperative Radiation Therapy, and Brachytherapy

Soft tissue sarcomas are rare mesenchymal cancers that pose a treatment challenge. Although small superficial soft tissue sarcomas can be managed by surgery alone, adjuvant radiotherapy in addition to limb-sparing surgery substantially increases local control of extremity sarcomas. Compared with postoperative radiotherapy, preoperative radiotherapy doubles the risk of a wound complication, but decreases the risk for late effects, which are generally irreversible. For retroperitoneal sarcomas, intraoperative radiotherapy can be used to safely escalate the radiation dose to the tumor bed. Patients with newly diagnosed sarcoma should be evaluated before surgery by a multidisciplinary team that includes a radiation oncologist.

The changing paradigm of tumour response to irradiation

Tumours contain multiple different cell populations, including cells derived from the bone marrow as well as cancer-associated fibroblasts and various stromal populations including the vasculature. The microenvironment of the tumour cells plays a significant role in the response of the tumour to radiation treatment. Low levels of oxygen (hypoxia) caused by the poorly organized vasculature in tumours have long been known to affect radiation response; however, other aspects of the microenvironment may also play important roles. This article reviews some of the old literature concerning tumour response to irradiation and relates this to current concepts about the role of the tumour microenvironment in tumour response to radiation treatment. Included in the discussion are the role of cancer stem cells, radiation damage to the vasculature and the potential for radiation to enhance immune activity against tumour cells. Radiation treatment can cause a significant influx of bone marrow-derived cell populations into both normal tissues and tumours. Potential roles of such cells may include enhancing vascular recovery as well as modulating immune reactivity.

Improving the Predictive Value of Preclinical Studies in Support of Radiotherapy Clinical Trials

There is an urgent need to improve reproducibility and translatability of preclinical data to fully exploit opportunities for molecular therapeutics involving radiation and radiochemotherapy. For in vitro research, the clonogenic assay remains the current state-of-the-art of preclinical assays, whereas newer moderate and high-throughput assays offer the potential for rapid initial screening. Studies of radiation response modification by molecularly targeted agents can be improved using more physiologic 3D culture models. Elucidating effects on the cancer stem cells (CSC, and CSC-like) and developing biomarkers for defining targets and measuring responses are also important. In vivo studies are necessary to confirm in vitro findings, further define mechanism of action, and address immunomodulation and treatment-induced modification of the microenvironment. Newer in vivo models include genetically engineered and patient-derived xenograft mouse models and spontaneously occurring cancers in domesticated animals. Selection of appropriate endpoints is important for in vivo studies; for example, regrowth delay measures bulk tumor killing, whereas local tumor control assesses effects on CSCs. The reliability of individual assays requires standardization of procedures and cross-laboratory validation. Radiation modifiers must be tested as part of clinical standard of care, which includes radiochemotherapy for most tumors. Radiation models are compatible with but also differ from those used for drug screening. Furthermore, the mechanism of a drug as a chemotherapeutic agent may be different from its interaction with radiation and/or radiochemotherapy. This provides an opportunity to expand the use of molecular-targeted agents. Clin Cancer Res; 22(13); 3138-47. ©2016 AACR.

How many new cancer patients in Europe will require radiotherapy by 2025? An ESTRO-HERO analysis

BACKGROUND

The objective of this HERO study was to assess the number of new cancer patients that will require at least one course of radiotherapy by 2025.

METHODS

European cancer incidence data by tumor site and country for 2012 and 2025 was extracted from the GLOBOCAN database. The projection of the number of new cases took into account demographic factors (age and size of the population). Population based stages at diagnosis were taken from four European countries. Incidence and stage data were introduced in the Australian Collaboration for Cancer Outcomes Research and Evaluation (CCORE) model.

RESULTS

Among the different tumor sites, the highest expected relative increase by 2025 in treatment courses was prostate cancer (24%) while lymphoma (13%), head and neck (12%) and breast cancer (10%) were below the average. Based on the projected cancer distributions in 2025, a 16% expected increase in the number of radiotherapy treatment courses was estimated. This increase varied across European countries from less than 5% to more than 30%.

CONCLUSION

With the already existing disparity in radiotherapy resources in mind, the data provided here should act as a leverage point to raise awareness among European health policy makers of the need for investment in radiotherapy.

Radiation oncology in the era of precision medicine

Technological advances and clinical research over the past few decades have given radiation oncologists the capability to personalize treatments for accurate delivery of radiation dose based on clinical parameters and anatomical information. Eradication of gross and microscopic tumours with preservation of health-related quality of life can be achieved in many patients. Two major strategies, acting synergistically, will enable further widening of the therapeutic window of radiation oncology in the era of precision medicine: technology-driven improvement of treatment conformity, including advanced image guidance and particle therapy, and novel biological concepts for personalized treatment, including biomarker-guided prescription, combined treatment modalities and adaptation of treatment during its course.

Oxaliplatin-containing Preoperative Therapy in Locally Advanced Rectal Cancer: Local Response, Toxicity and Long-term Outcome

AIMS

This non-randomised study was undertaken to examine oxaliplatin as possibly an intensifying component of sequential neoadjuvant therapy in locally advanced rectal cancer for improved local and metastatic outcome.

MATERIALS AND METHODS

Ninety-seven patients (57 T2-3 cases, 40 T4 cases) received two cycles of the Nordic FLOX regimen (oxaliplatin 85 mg/m(2) day 1 and bolus 5-fluorouracil 500 mg/m(2) and folinic acid 100 mg days 1 and 2) before long-course chemoradiotherapy with concomitant oxaliplatin and capecitabine, followed by pelvic surgery. Treatment toxicity, local tumour response and long-term outcome were recorded.

RESULTS

Good histologic tumour regression was obtained in 72% of patients. Implementing protocol-specific dose adjustments, tolerance was acceptable and 95% of patients received the total prescribed radiation dose. Estimated 5 year progression-free and overall survival were 61% and 83%, respectively. T4 stage was associated with an inferior local response rate, which again was highly associated with impaired long-term outcome.

CONCLUSIONS

In this cohort of rectal cancer patients dominated by T4 and advanced T3 cases given sequential oxaliplatin-containing preoperative therapy with acceptable toxicity, high tumour response rates and overall survival were obtained, consistent with both local and systemic effects. However, tumour response and long-term outcome remained inferior for a significant number of T4 cases, suggesting that the T4 entity is biologically heterogeneous with subgroups of patients eligible for further individualisation of therapy.

Preclinical Data on Efficacy of 10 Drug-Radiation Combinations: Evaluations, Concerns, and Recommendations

BACKGROUND

Clinical testing of new therapeutic interventions requires comprehensive, high-quality preclinical data. Concerns regarding quality of preclinical data have been raised in recent reports. This report examines the data on the interaction of 10 drugs with radiation and provides recommendations for improving the quality, reproducibility, and utility of future studies. The drugs were AZD6244, bortezomib, 17-DMAG, erlotinib, gefitinib, lapatinib, oxaliplatin/Lipoxal, sunitinib (Pfizer, Corporate headquarters, New York, NY), thalidomide, and vorinostat.

METHODS

In vitro and in vivo data were tabulated from 125 published papers, including methods, radiation and drug doses, schedules of administration, assays, measures of interaction, presentation and interpretation of data, dosimetry, and conclusions.

RESULTS

In many instances, the studies contained inadequate or unclear information that would hamper efforts to replicate or intercompare the studies, and that weakened the evidence for designing and conducting clinical trials. The published reports on these drugs showed mixed results on enhancement of radiation response, except for sunitinib, which was ineffective.

CONCLUSIONS

There is a need for improved experimental design, execution, and reporting of preclinical testing of agents that are candidates for clinical use in combination with radiation. A checklist is provided for authors and reviewers to ensure that preclinical studies of drug-radiation combinations meet standards of design, execution, and interpretation, and report necessary information to ensure high quality and reproducibility of studies. Improved design, execution, common measures of enhancement, and consistent interpretation of preclinical studies of drug-radiation interactions will provide rational guidance for prioritizing drugs for clinical radiotherapy trials and for the design of such trials.

Exploiting biological and physical determinants of radiotherapy toxicity to individualize treatment

The recent advances in radiation delivery can improve tumour control probability (TCP) and reduce treatment-related toxicity. The use of intensity-modulated radiotherapy (IMRT) in particular can reduce normal tissue toxicity, an objective in its own right, and can allow safe dose escalation in selected cases. Ideally, IMRT should be combined with image guidance to verify the position of the target, since patients, target and organs at risk can move day to day. Daily image guidance scans can be used to identify the position of normal tissue structures and potentially to compute the daily delivered dose. Fundamentally, it is still the tolerance of the normal tissues that limits radiotherapy (RT) dose and therefore tumour control. However, the dose-response relationships for both tumour and normal tissues are relatively steep, meaning that small dose differences can translate into clinically relevant improvements. Differences exist between individuals in the severity of toxicity experienced for a given dose of RT. Some of this difference may be the result of differences between the planned dose and the accumulated dose (DA). However, some may be owing to intrinsic differences in radiosensitivity of the normal tissues between individuals. This field has been developing rapidly, with the demonstration of definite associations between genetic polymorphisms and variation in toxicity recently described. It might be possible to identify more resistant patients who would be suitable for dose escalation, as well as more sensitive patients for whom toxicity could be reduced or avoided. Daily differences in delivered dose have been investigated within the VoxTox research programme, using the rectum as an example organ at risk. In patients with prostate cancer receiving curative RT, considerable daily variation in rectal position and dose can be demonstrated, although the median position matches the planning scan well. Overall, in 10 patients, the mean difference between planned and accumulated rectal equivalent uniform doses was -2.7 Gy (5%), and a dose reduction was seen in 7 of the 10 cases. If dose escalation was performed to take rectal dose back to the planned level, this should increase the mean TCP (as biochemical progression-free survival) by 5%. Combining radiogenomics with individual estimates of DA might identify almost half of patients undergoing radical RT who might benefit from either dose escalation, suggesting improved tumour cure or reduced toxicity or both.

Personalized radiotherapy: concepts, biomarkers and trial design

In the past decade, and pointing onwards to the immediate future, clinical radiotherapy has undergone considerable developments, essentially including technological advances to sculpt radiation delivery, the demonstration of the benefit of adding concomitant cytotoxic agents to radiotherapy for a range of tumour types and, intriguingly, the increasing integration of targeted therapeutics for biological optimization of radiation effects. Recent molecular and imaging insights into radiobiology will provide a unique opportunity for rational patient treatment, enabling the parallel design of next-generation trials that formally examine the therapeutic outcome of adding targeted drugs to radiation, together with the critically important assessment of radiation volume and dose-limiting treatment toxicities. In considering the use of systemic agents with presumed radiosensitizing activity, this may also include the identification of molecular, metabolic and imaging markers of treatment response and tolerability, and will need particular attention on patient eligibility. In addition to providing an overview of clinical biomarker studies relevant for personalized radiotherapy, this communication will highlight principles in addressing clinical evaluation of combined-modality-targeted therapeutics and radiation. The increasing number of translational studies that bridge large-scale omics sciences with quality-assured phenomics end points-given the imperative development of open-source data repositories to allow investigators the access to the complex data sets-will enable radiation oncology to continue to position itself with the highest level of evidence within existing clinical practice.

Tumor phosphatidylinositol 3-kinase signaling in therapy resistance and metastatic dissemination of rectal cancer: opportunities for signaling-adapted therapies

Locally advanced rectal cancer (LARC) comprises heterogeneous tumors with predominant hypoxic components, a hallmark of the tumor microenvironment and determinant of resistance to cytotoxic therapies, local recurrence, and metastatic progression. A rational integration of molecularly targeted agents in established combined-modality treatment regimens may improve local and systemic disease control, but will require a clear definition of functional biomarkers for patient stratification. In a prospective study of LARC patients given neoadjuvant chemotherapy and radiation, we applied a kinase substrate array technology to analyze the patients' tumor biopsies sampled at the time of diagnosis, and observed that receptor tyrosine kinase activities integrated by high phosphatidylinositol 3-kinase signaling were correlated both with poor tumor response to the neoadjuvant treatment and adverse progression-free survival. Conceptually, the specific tumor signature of phosphatidylinositol 3-kinase signaling activity may point to actionable therapy targets in LARC patients with unfavorable disease features. Clinical trial registration number NCT00278694.