Focal Radiation Research Articles

Identifying Gene-Treatment Interactions and Targetable Radiation Vulnerabilities in Glioblastoma through Coupling of In Vivo CRISPR Perturbation and Single Cell Transcriptomics

Glioblastoma (GBM) is an incurable brain tumor comprised of dynamic malignant cell states and microenvironment components that underlie treatment resistance. Here we use genome-wide CRISPR/Cas9 functional genomics to define biological drivers and therapeutic vulnerabilities across human and mouse GBM models. To interrogate these mechanisms in the context of the tumor microenvironment and in vivo physiology, we established in vivo Perturb-seq intracranially, a technique coupling functional genomics with single cell transcriptomics, where each cell is an individual experiment. Orthotopic intracranial tumor models were established using human (GBM6, GBM43) or mouse (GL261, SB28) GBM cells stably expressing CRISPR interference (CRISPRi) machinery. Perturb-seq target selection for phenotyping of gene-treatment interactions was performed using genome-wide CRISPRi screens ± radiotherapy in cell cultures. Dual sgRNA lentivirus libraries were transduced either ex vivo prior to intracranial GBM cell transplantation or in vivo using intratumor convection enhanced delivery (CED). Transcriptional phenotyping was performed using single-cell RNA-seq with CRISPR direct capture following focal brain radiotherapy (2 Gy x 5) or mock treatment. GBM cell states were validated using single-nucleus RNA-seq data from 86 primary-recurrent patient-matched GBMs. Mechanistic and functional validation was performed using small molecule inhibitors, immunohistochemistry, clonogenic assays, and in vivo survival experiments. In vivo Perturb-seq ± radiotherapy of 48 genes underlying GBM radiotherapy responses, which were enriched for DNA damage response and metabolic pathways, was performed in > 425,000 single cells. Radiotherapy induced 16 distinct GBM cell states, and genetic perturbations reprogrammed these cell states in a treatment-dependent fashion. Quantitative modeling of gene/radiotherapy interactions using high dimensional manifolds revealed in vivo-specific genetic dependencies. We revealed a critical role for Prkdc, the catalytic subunit of DNA-dependent protein kinase (DNA-PK), as a radiotherapy sensitizer through regulation of cell intrinsic growth and oxidative stress pathways, and cell extrinsic interferon and signaling pathways that altered cell-cell interactions in vivo. These pathways were also disrupted in single-nucleus RNA-seq analysis of post-radiotherapy human GBM tumors. Inhibition of Prkdc using a Food and Drug Administration approved small molecule sensitized GBM cells to radiotherapy and extended survival in mice harboring human intracranial xenografts. We establish in vivo Perturb-seq in orthotopic GBM models as a platform for simultaneous functional genomic discovery and characterization of therapeutic targets, revealing an underappreciated role for Prkdc in GBM tumors in vivo that is targetable using small molecules. These tools are adaptable for a wide range of disease models and treatment modalities.

Role of ATP Binding Cassette Subfamily A Member 1 (ABCA1) in Chemoradiotherapy-induced Renal Injury

Radiation therapy (RT) alone or combined with chemotherapy reduces cholesterol efflux and causes chronic kidney disease (CKD). There is no treatment for CKD except renal replacement strategies such as dialysis or transplantation. We hypothesize that cancer treatment-induced ABCA1 deficiency leads to dysregulation of cholesterol metabolism, making podocytes susceptible and cancerous cells resistant to treatment-induced injuries. To quantify the cell index of LNCaP, 786-0, and Podcytes were grown in an e-plate reader (Roche) for 24 h and then were treated with either enzalutamide (10µM) or sunitinib (1.0 µM) or cyclophosphamide (10µM) with or without RT (4Gy) or ABCA1 inducer (liver-X-receptors agonist (GW3965; Sigma; 10µM). Podocyte cholesterol efflux assay was measured using NBD-cholesterol efflux assay, and expression of ABCA1 and cleaved caspase-3 were measured by western blotting. 10-14-week-old C57BL/6 male and female mice were given bilateral kidney X-irradiation of 4Gy with or without cisplatin (3mg/kg; IV). Functional kidney parameters, histopathological changes, and ultrastructural changes were measured at baseline and 20 weeks after treatment. GFR was measured using a FITC-sinistrin-based transdermal monitor. In vitro studies suggest that after radiation exposure (4Gy and 8Gy), ABCA1 expression decreases in a dose and time-dependent manner in cultured podocytes (p < 0.05), which coincides with reduced cholesterol efflux (p < 0.05) and increased podocyte apoptosis (p < 0.01). In contrast, LXR agonist treatment in vitro prevents reduced ABCA1 expression and cholesterol efflux and prevents podocytes from radiation-induced apoptosis. Our in vitro studies further suggest that Enzalutamide treatment alone reduces the growth of LNCaP and podocytes, and RT (5Gy) plus enzalutamide combination treatment further decreases the growth of LNCaP and podocytes. However, LXR agonist treatment further increased the efficacy of enzalutamide and RT treatment against LNCaP and increased podocyte growth simultaneously. Similarly, Sunitinib with or without RT reduces the growth of renal cancer cells (786-0) and podocytes. LXR agonist treatment further increases the efficacy of the sunitinib and RT against 786-0 cells and simultaneously increases podocyte growth. Cyclophosphamide reduces the growth of the podocytes, and LXR agonist treatment improves the podocyte growth after CP treatment. In vivo studies observed that focal bilateral kidney irradiation with or without cisplatin of C57BL/6 mice induces lipid accumulation in the kidney cortex and increases GBM thickness (p < 0.001), which correlates with decreased Abca1 expression, podocyte number, and GFR. This study shows that LXR agonist treatment protects podocytopathy in vitro and chemotherapy or radiotherapy-induced kidney injury in vivo. ABCA1 may be an important therapeutic target for chemoradiotherapy-induced kidney injuries in cancer patients.

Radiotherapy Shows Synergistic Anti-Tumor Efficacy with Treg Depletion by Reprogramming the Immune-Excluded Tumor Microenvironment

Tumor-infiltrating Treg cells (TITR) negatively regulates anti-tumor immune response and promotes tumor progression. Increased levels of TITR cells have been associated with poor prognosis in multiple cancer indications which led to the development of immunotherapies that target tumor Tregs. CCR8 antibody is one of the best-in-class therapies in clinical development for depleting TITR cells. It has demonstrated potent efficacy in tumors that are responsive to checkpoint inhibitors but failed in cold tumors that lack immune infiltration and activation. Radiotherapy (RT) has been shown to induce pro-inflammatory responses in tumors, but still failed to show consistent synergy with checkpoint inhibitors. Here we test the hypothesis that RT synergizes with Treg depletion to improve anti-tumor efficacy by reprogramming the immune-excluded tumor microenvironment. The CCR8 + RT combination therapy was tested in syngeneic mouse tumor models: 4T1 breast, LL2 lung, and B16F10 melanoma, all of which present a cold tumor phenotype. Tumor-bearing mice (n = 10 per group) received a single dose of focal irradiation by SARRP, 4 doses of anti-CCR8 depleting antibody or a combination of the two. Tumor size was measured 3 times per week, survival was monitored until day 42, and tumor metastasis was evaluated at endpoint by necropsy. Mouse tumors, spleens, draining lymph nodes, and blood were collected 1 day after the last dose of CCR8 therapy and analyzed by multi-color flow cytometry and RNA-sequencing for pharmacodynamics and mechanism studies. In the syngeneic mouse models, CCR8+RT combination therapy displayed significantly improved tumor growth inhibition, metastasis control, and prolonged survival compared with either treatment alone, without increase in toxicity. Flow cytometry showed reduced TITR population and increased infiltration and activation of CD8+ cytotoxic T cells in the tumors of CCR8 + RT treated mice. Increased activation of CD8+ T cells was also observed in the blood and draining lymph nodes in mice treated with the combination therapy. Moreover, transcriptomic analysis identified up-regulation of pathways associated with TNF-α and IFN-γ response in the combination-treated tumors, suggesting the creation of a pro-inflammatory tumor microenvironment. Interestingly, these changes were only induced by the combination therapy, but not either treatment alone. Immunotherapies targeting Treg/TITR cells have so far failed to show promise in clinical trials. Our data suggest that TITR depletion is not sufficient to treat tumors with minimal immune infiltration. Our animal data demonstrate that combining RT with CCR8 therapy significantly inhibited tumor growth and prevented metastasis by enriching the tumor microenvironment with pro-inflammatory cytokines and activated cytotoxic T cells. These findings have clinical relevance to apply TITR depletion therapy in combination with RT.

Immunologically relevant effects of radiation therapy on the tumor microenvironment.

Focal radiation therapy (RT) has been successfully employed to clinically manage multiple types of cancer for more than a century. Besides being preferentially cytotoxic for malignant cells over their nontransformed counterparts, RT elicits numerous microenvironmental alterations that appear to factor into its therapeutic efficacy. Here, we briefly discuss immunostimulatory and immunosuppressive microenvironmental changes elicited by RT and their impact on tumor recognition by the host immune system.

Modern Stereotactic Radiotherapy for Brain Metastases from Lung Cancer: Current Trends and Future Perspectives Based on Integrated Translational Approaches.

Brain metastases (BMs) represent the most frequent metastatic event in the course of lung cancer patients, occurring in approximately 50% of patients with non-small-cell lung cancer (NSCLC) and in up to 70% in patients with small-cell lung cancer (SCLC). Thus far, many advances have been made in the diagnostic and therapeutic procedures, allowing improvements in the prognosis of these patients. The modern approach relies on the integration of several factors, such as accurate histological and molecular profiling, comprehensive assessment of clinical parameters and precise definition of the extent of intracranial and extracranial disease involvement. The combination of these factors is pivotal to guide the multidisciplinary discussion and to offer the most appropriate treatment to these patients based on a personalized approach. Focal radiotherapy (RT), in all its modalities (radiosurgery (SRS), fractionated stereotactic radiotherapy (SRT), adjuvant stereotactic radiotherapy (aSRT)), is the cornerstone of BM management, either alone or in combination with surgery and systemic therapies. We review the modern therapeutic strategies available to treat lung cancer patients with brain involvement. This includes an accurate review of the different technical solutions which can be exploited to provide a "state-of-art" focal RT and also a detailed description of the systemic agents available as effective alternatives to SRS/SRT when a targetable molecular driver is present. In addition to the validated treatment options, we also discuss the future perspective for focal RT, based on emerging clinical reports (e.g., SRS for patients with many BMs from NSCLC or SRS for BMs from SCLC), together with a presentation of innovative and promising findings in translational research and the combination of novel targeted agents with SRS/SRT.

Intrinsic tumor resistance to CAR T cells is a dynamic transcriptional state that is exploitable with low-dose radiation.

Chimeric antigen receptor (CAR) T-cell therapy represents a major advancement for hematologic malignancies, with some patients achieving long-term remission. However, the majority of treated patients still die of their disease. A consistent predictor of response is tumor quantity, wherein a higher disease burden before CAR T-cell therapy portends a worse prognosis. Focal radiation to bulky sites of the disease can decrease tumor quantity before CAR T-cell therapy, but whether this strategy improves survival is unknown. We find that substantially reducing systemic tumor quantity using high-dose radiation to areas of bulky disease, which is commonly done clinically, is less impactful on overall survival in mice achieved by CAR T cells than targeting all sites of disease with low-dose total tumor irradiation (TTI) before CAR T-cell therapy. This finding highlights another predictor of response, tumor quality, the intrinsic resistance of an individual patient's tumor cells to CAR T-cell killing. Little is known about whether or how an individual tumor's intrinsic resistance may change under different circumstances. We find a transcriptional "death receptor score" that reflects a tumor's intrinsic sensitivity to CAR T cells can be temporarily increased by low-dose TTI, and the timing of this transcriptional change correlates with improved invivo leukemia control by an otherwise limited number of CAR T cells. This suggests an actionable method for potentially improving outcomes in patients predicted to respond poorly to this promising therapy and highlights that intrinsic tumor attributes may be equally or more important predictors of CAR T-cell response as tumor burden.

P11.06.B PERFUSION MRI IMPACTS MANAGEMENT IN PATIENTS WITH TREATED GLIOMA: FIRST RESULTS FROM THE PERISCOPE PROJECT

Abstract BACKGROUND Perfusion MRI (pMRI) is widely used for differentiation between progressive disease and pseudoprogression in patients with treated glioma. Although pMRI has long been available, its clinical relevance and utilization are not well known. We investigate the role of pMRI in clinical management decisions and its association with overall survival (OS) in patients with glioma under surveillance after focal radiotherapy. MATERIALS AND METHODS We performed a retrospective multicenter cohort study of patients treated for glioma between 2008 and 2021. At the moment of first substantial abnormalities on follow-up MRI, both with or without pMRI, we collected the management decisions, information about the (p)MRI and clinical parameters from the patient records. Causal inference methods were used to design a model predicting the probability of a management change with or without pMRI at first scan after radiotherapy (baseline), during chemotherapy (on-treatment) and after treatment. A multivariable Cox-proportional hazards model was used for OS analysis (adjusted for age, clinical performance, surgery type, histopathological diagnosis). Subgroup analyses were performed for patients with glioblastoma only. RESULTS 976 patients (mean age 57.2 ±12.4 years; 649 men) were included in 7 neuro-oncological referral centers (4 academic), 548 with and 428 without pMRI. Eighty percent of pMRI scans were of sufficient quality. Eighty percent of patients had glioblastoma and in this group, during the “on-treatment” phase, there was a 16% lower probability of change in clinical management in patients with pMRI, which was more pronounced (37%) in academic hospitals. OS was longer in patients with versus without pMRI with a hazard ratio of 0.77 (95%CI: 0.67,0.89, p&amp;lt;0.001). These findings were similar when only considering patients with glioblastoma. CONCLUSION pMRI was associated with fewer management changes while patients were on treatment, and with longer OS. This latter result must be interpreted with caution due to possible confounding.:

Long-term survival in patients with brain metastases-clinical characterization of arare scenario.

This study aimed to assess clinical, treatment, and prognostic features in patients with brain metastases (BM) from solid tumors achieving long-term survival (LTS). Further, the accuracy of diagnosis-specific Graded Prognostic Assessment scores (ds-GPA) to predict LTS was evaluated. Patients admitted for radiotherapy of BM between 2010 and 2020 at alarge tertiary cancer center with survival of at least 3years from diagnosis of BM were included. Patient, tumor, treatment characteristics and ds-GPA were compiled retrospectively. From atotal of 1248patients with BM, 61 (4.9%) survived ≥ 3years. In 40patients, detailed patient charts were available. Among LTS patients, median survival time from diagnosis of BM was 51.5months. Most frequent primary tumors were lung cancer (45%), melanoma (20%), and breast cancer (17.5%). At the time of diagnosis of BM, 11/40patients (27.5%) had oligometastatic disease. Estimated mean survival time based on ds-GPA was 19.7months (in 8cases estimated survival < 12months). Resection followed by focal or whole-brain radiotherapy (WBRT) was often applied (60%), followed by primary stereotactic radiotherapy (SRT) (20%) or WBRT (20%). 80% of patients received systemic treatment, appearing particularly active in specifically altered non-small lung cancer (NSCLC), melanoma, and HER2-positive breast cancer. Karnofsky performance score (KPS) and the presence of oligometastatic disease at BM diagnosis were persisting prognostic factors in LTS patients. In this monocentric setting reflecting daily pattern of care, LTS with BM is heterogeneous and difficult to predict. Effective local treatment and modern systemic therapies often appear crucial for LTS. The impact of concomitant diseases and frailty is not clear.

Characterization of a commercial bioluminescence tomography-guided system for pre-clinical radiation research.

Widely used Cone-beam computed tomography (CBCT)-guided irradiators have limitations in localizing soft tissue targets growing in a low-contrast environment. This hinders small animal irradiators achieving precise focal irradiation. To advance image-guidance for soft tissue targeting, we developed a commercial-grade bioluminescence tomography-guided system (BLT, MuriGlo) for pre-clinical radiation research. We characterized the system performance and demonstrated its capability in target localization. We expect this study can provide a comprehensive guideline for the community in utilizing the BLT system for radiation studies. MuriGlo consists of four mirrors, filters, lens, and charge-coupled device (CCD) camera, enabling a compact imaging platform and multi-projection and multi-spectral BLT. A newly developed mouse bed allows animals imaged in MuriGlo and transferred to a small animal radiation research platform (SARRP) for CBCT imaging and BLT-guided irradiation. Methods and tools were developed to evaluate the CCD response linearity, minimal detectable signal, focusing, spatial resolution, distortion, and uniformity. A transparent polycarbonate plate covering the middle of the mouse bed was used to support and image animals from underneath the bed. We investigated its effect on 2D Bioluminescence images and 3D BLT reconstruction accuracy, and studied its dosimetric impact along with the rest of mouse bed. A method based on pinhole camera model was developed to map multi-projection bioluminescence images to the object surface generated from CBCT image. The mapped bioluminescence images were used as the input data for the optical reconstruction. To account for free space light propagation from object surface to optical detector, a spectral derivative (SD) method was implemented for BLT reconstruction. We assessed the use of the SD data (ratio imaging of adjacent wavelength) in mitigating out of focusing and non-uniformity seen in the images. A mouse phantom was used to validate the data mapping. The phantom and an in vivo glioblastoma model were utilized to demonstrate the accuracy of the BLT target localization. The CCD response shows good linearity with<0.6% residual from a linear fit. The minimal detectable level is 972 counts for 10×10 binning. The focal plane position is within the range of 13-18mm above the mouse bed. The spatial resolution of 2D optical imaging is<0.3mm at Rayleigh criterion. Within the region of interest, the image uniformity is within 5% variation, and image shift due to distortion is within 0.3mm. The transparent plate caused<6% light attenuation. The use of the SD imaging data can effectively mitigate out of focusing, image non-uniformity, and the plate attenuation, to support accurate multi-spectral BLT reconstruction. There is<0.5% attenuation on dose delivery caused by the bed. The accuracy of data mapping from the 2D bioluminescence images to CBCT image is within 0.7mm. Our phantom test shows the BLT system can localize a bioluminescent target within 1mm with an optimal threshold and only 0.2mm deviation was observed for the case with and without a transparent plate. The same localization accuracy can be maintained for the in vivo GBM model. This work is the first systematic study in characterizing the commercial BLT-guided system. The information and methods developed will be useful for the community to utilize the imaging system for image-guided radiation research.

Radiation therapy promotes unsaturated fatty acids to maintain survival of glioblastoma

Radiation therapy (RT) is essential for the management of glioblastoma (GBM). However, GBM frequently relapses within the irradiated margins, thus suggesting that RT might stimulate mechanisms of resistance that limits its efficacy. GBM is recognized for its metabolic plasticity, but whether RT-induced resistance relies on metabolic adaptation remains unclear.Here, we show in vitro and in vivo that irradiated GBM tumors switch their metabolic program to accumulate lipids, especially unsaturated fatty acids. This resulted in an increased formation of lipid droplets to prevent endoplasmic reticulum (ER) stress. The reduction of lipid accumulation with genetic suppression and pharmacological inhibition of the fatty acid synthase (FASN), one of the main lipogenic enzymes, leads to mitochondrial dysfunction and increased apoptosis of irradiated GBM cells. Combination of FASN inhibition with focal RT improved the median survival of GBM-bearing mice. Supporting the translational value of these findings, retrospective analysis of the GLASS consortium dataset of matched GBM patients revealed an enrichment in lipid metabolism signature in recurrent GBM compared to primary.Overall, these results demonstrate that RT drives GBM resistance by generating a lipogenic environment permissive to GBM survival. Targeting lipid metabolism might be required to develop more effective anti-GBM strategies.

Opportunities and Alternatives of Modern Radiation Oncology and Surgery for the Management of Resectable Brain Metastases.

Postsurgical radiotherapy (RT) has been early proven to prevent local tumor recurrence, initially performed with whole brain RT (WBRT). Subsequent to disadvantageous cognitive sequalae for the patient and the broad distribution of modern linear accelerators, focal irradiation of the tumor has omitted WBRT in most cases. In many studies, the effectiveness of local RT of the resection cavity, either as single-fraction stereotactic radiosurgery (SRS) or hypo-fractionated stereotactic RT (hFSRT), has been demonstrated to be effective and safe. However, whereas prospective high-level incidence is still lacking on which dose and fractionation scheme is the best choice for the patient, further ablative techniques have come into play. Neoadjuvant SRS (N-SRS) prior to resection combines straightforward target delineation with an accelerated post-surgical phase, allowing an earlier start of systemic treatment or rehabilitation as indicated. In addition, low-energy intraoperative RT (IORT) on the surgical bed has been introduced as another alternative to external beam RT, offering sterilization of the cavity surface with steep dose gradients towards the healthy brain. This consensus paper summarizes current local treatment strategies for resectable brain metastases regarding available data and patient-centered decision-making.

ReIGNITE Radiation Therapy Boost: A Prospective, International Study of Radiation Oncologists’ Accuracy in Contouring Prostate Tumors for Focal Radiation Therapy Boost on Conventional Magnetic Resonance Imaging Alone or With Assistance of Restriction Spectrum Imaging

In a phase III randomized trial, adding a radiation boost to tumor(s) visible on MRI improved prostate cancer (PCa) disease-free and metastasis-free survival without additional toxicity. Radiation oncologists' ability to identify prostate tumors is critical to widely adopting intraprostatic tumor radiotherapy boost for patients. A diffusion MRI biomarker, called the Restriction Spectrum Imaging restriction score (RSIrs), has been shown to improve radiologists' identification of clinically significant PCa. We hypothesized that (1) radiation oncologists would find accurately delineating PCa tumors on conventional MRI challenging and (2) using RSIrs maps would improve radiation oncologists' accuracy for PCa tumor delineation. In this multi-institutional, international, prospective study, 44 radiation oncologists (participants) and 2 expert radiologists (experts) contoured prostate tumors on 39 total patient cases using conventional MRI with or without RSIrs maps. Participant volumes were compared to the consensus expert volumes. Contouring accuracy metrics included percent overlap with expert volume, Dice coefficient, conformal number, and maximum distance beyond expert volume. 1604 participant volumes were produced. 40 of 44 participants (91%) completely missed ≥1 expert-defined target lesion without RSIrs, compared to 13 of 44 (30%) with RSIrs maps. On conventional MRI alone, 134 of 762 contour attempts (18%) completely missed the target, compared to 18 of 842 (2%) with RSIrs maps. Use of RSIrs maps improved all contour accuracy metrics by approximately 50% or more. Mixed effects modeling confirmed that RSIrs maps were the main variable driving improvement in all metrics. System Usability Scores indicated RSIrs maps significantly improved the contouring experience (72 vs. 58, p < 0.001). Radiation oncologists struggle with accurately delineating visible PCa tumors on conventional MRI. RSIrs maps improve radiation oncologists' ability to target MRI-visible tumors for prostate tumor boost.

ACQUIRED PTEN LOSS MAY MEDIATE DABRAFENIB AND TRAMETINIB RESISTANCE IN BRAF V600E–MUTATED EPITHELIOID GLIOBLASTOMA: A CASE REPORT

Abstract Epithelioid glioblastoma is a rare variant of glioblastoma that primarily affects children and young adults. This commonly has a BRAF V600E mutation and can be treated with BRAF and MEK inhibitors. CASE DESCRIPTION: An 18-year-old woman was diagnosed with an epithelioid glioblastoma. She received temozolomide chemoradiotherapy. Upon progression she had redo surgery and received dabrafenib and trametinib. The patient developed a drop metastasis to the cervical spine, and consequently received focal radiotherapy, 20 Gy in five fractions. Treatments were halted six months after her second resection due to further disease progression. She developed uncal herniation, requiring her to have a third resection approximately six months after her second resection. She passed away after this, 12 months following her initial diagnosis. Retrospective genetic analysis of three tumor specimens showed a novel PTEN mutation that arose after her first surgery. We suspect that the acquired PTEN mutation conferred resistance to dabrafenib and trametinib. DISCUSSION: This case offers teaching points and research questions. Firstly, early treatment with BRAF and MEK inhibitors in high grade BRAF V600E–mutated gliomas may be optimal as the patient may have stabilized with earlier treatment on dabrafenib and trametinib. Secondly, further studies are required to investigate whether the addition of PTEN mutation to BRAF V600E leads to aggressive tumor behavior. Lastly, there is a need for investigation into potential benefits of treating similar patients by co-targeting the BRAF and PI3K/AKT pathways.

A Phase 1 Trial of Focal Salvage Stereotactic Body Radiation Therapy for Radiorecurrent Prostate Cancer

NCT03253744 was a phase 1 trial to identify the maximum tolerated dose (MTD) of image-guided, focal, salvage stereotactic body radiation therapy (SBRT) for patients with locally radiorecurrent prostate cancer. Additional objectives included biochemical control and imaging response. The trial design included 3 dose levels (DLs): 40 Gy (DL1), 42.5 Gy (DL2), and 45 Gy (DL3) in 5 fractions delivered ≥48 hours apart. The prescription dose was delivered to the magnetic resonance- and prostate-specific membrane antigen imaging-defined tumor volume. Dose escalation followed a 3+3 design with a 3-patient expansion at the MTD. Toxicities were scored until 2 years after completion of SBRT using Common Terminology Criteria for Adverse Events, version 5.0, criteria. Escalation was halted if 2 dose-limiting toxicities occurred, defined as any persistent (>4 days) grade 3 toxicity occurring within the first 3 weeks after SBRT and any grade 3 genitourinary (GU) or grade 4 gastrointestinal (GI) toxicity thereafter. Between August 2018 and May 2022, 8 patients underwent salvage focal SBRT, with a median follow-up of 35 months. No dose-limiting toxic effects were observed on DL1. Two patients were enrolled in DL2 and experienced grade 3 GU toxicities, prompting de-escalation and expansion (n=6) at the MTD (DL1). The most common toxicities observed were grade ≥2 GU toxicities, with only a single grade 2 GI toxicity and no grade ≥3 GI toxicities. One patient experienced biochemical failure (prostate-specific antigen nadir+2.0) at 33 months. The MTD for focal salvage SBRT for isolated intraprostatic radiorecurrence was 40 Gy in 5 fractions, producing a 100% 24-month biochemical progression free survival, with 1 poststudy failure at 33 months. The most frequent clinically significant toxicity was late grade ≥2 GU toxicity.

A molybdenum nanostructured-film target for tunable x-ray sources: surface-structure controllable preparing and radiation intensity selecting

Tunable x-ray sources have attracted interest due to providing selective focal spots and radiation intensities for different specific uses. Surface-structure of the anode target has a non-negligible impact on the radiation intensity of x-ray sources. The metal molybdenum (Mo) Lα characteristic x-ray exhibits great potential in solving key scientific problems of material analysis. However, there is still a lack of research on how to flexibly use Mo structure targets to meet the application requirements of different x-ray radiation devices. The reliable preparation of Mo targets with suitable surface-structure is also a significant challenge, particularly for those nanostructured-film targets that cannot be machined. In this study, we successfully prepared a series of self-assembled Mo nanostructured-films with controllable surface structures as a class of reflection-type x-ray sources’ anode target. The structure-activity relationship between the Mo surface nanostructures and the radiating Lα x-ray performance at different anode target angles was studied in a reflecting device layout. Mo nanostructures with smoother surface typically show better radiation performance at small inclination angles (0° to 30°), while the Mo films with a large number of nanoparticles and rough surface exhibit advantages at large inclination angles (60° to 80°). The results provide a feasible scheme for the future application of multi-functional tunable x-ray sources.

Plaque brachytherapy - Radiating positivity.

Plaque brachytherapy is an evolving, yet effective globe and vision-sparing modality for the treatment of intraocular tumors by transscleral irradiation of the tumor base with a radioactive implant. The American Brachytherapy Society (ABS) along with the collaboration of the international multicenter Ophthalmic Oncology Task Force (OOTF) was assembled to reach a consensus regarding establishing practice guidelines and setting standards of care for intraocular tumors. The advent of plaque brachytherapy has revolutionized the outcomes of intraocular tumors, thus ensuring globe salvage, reducing morbidity and mortality, and avoiding cosmetic disfigurement. A well-planned dosimetry for plaque brachytherapy results in achieving local tumor control and excellent prognosis. This technique provides the advantage of focal radiation, thus eliminating the damage to the adjacent structures, minimal periorbital tissue damage, absence of cosmetic disfigurement owing to lack of retarded bone growth as seen in external beam radiotherapy. Thus, it reduces the risk of metastasis, and with the recent advances, it provides a shorter duration of treatment. : In this video, we shall display the concept of plaque brachytherapy, the various types of plaques available, different radiations sources, planning dosimetry and calculations, target disease spectrum, surgical placement, and post-radiation outcomes in terms of local tumor control and prognosis. This video highlights the history, basic principles and techniques of plaque brachytherapy and provides an understanding of its applications in the world of ocular oncology. https://youtu.be/7PX0mDQETRY.

Rapid recruitment and IFN-I-mediated activation of monocytes dictate focal radiotherapy efficacy.

The recruitment of monocytes and their differentiation into immunosuppressive cells is associated with the low efficacy of preclinical nonconformal radiotherapy (RT) for tumors. However, nonconformal RT (non-CRT) does not mimic clinical practice, and little is known about the role of monocytes after RT modes used in patients, such as conformal RT (CRT). Here, we investigated the acute immune response induced by after CRT. Contrary to non-CRT approaches, we found that CRT induces a rapid and robust recruitment of monocytes to the tumor that minimally differentiate into tumor-associated macrophages or dendritic cells but instead up-regulate major histocompatibility complex II and costimulatory molecules. We found that these large numbers of infiltrating monocytes are responsible for activating effector polyfunctional CD8+ tumor-infiltrating lymphocytes that reduce tumor burden. Mechanistically, we show that monocyte-derived type I interferon is pivotal in promoting monocyte accumulation and immunostimulatory function in a positive feedback loop. We also demonstrate that monocyte accumulation in the tumor microenvironment is hindered when RT inadvertently affects healthy tissues, as occurs in non-CRT. Our results unravel the immunostimulatory function of monocytes during clinically relevant modes of RT and demonstrate that limiting the exposure of healthy tissues to radiation has a positive therapeutic effect on the overall antitumor immune response.

Dose-Volume Histogram Parameters and Quality of Life in Patients with Prostate Cancer Treated with Surgery and High-Dose Volumetric-Intensity-Modulated Arc Therapy to the Prostate Bed.

Prostate bed radiotherapy (RT) is a major affecter of patients' long-term quality of life (QoL). To ensure the best possible outcome of these patients, dose constraints are key for optimal RT planning and delivery. However, establishing refined dose constraints requires access to patient-level data. Therefore, we aimed to provide such data on the relationship between OAR and gastrointestinal (GI) as well as genitourinary (GU) QoL outcomes of a homogenous patient cohort who received dose-intensified post-operative RT to the prostate bed. Furthermore, we aimed to conduct an exploratory analysis of the resulting data. Patients who were treated with prostate bed RT between 2010 and 2020 were inquired about their QoL based on the Expanded Prostate Cancer Index Composite (EPIC). Those (n = 99) who received volumetric arc therapy (VMAT) of at least 70 Gy to the prostate bed were included. Dose-volume histogram (DVH) parameters were gathered and correlated with the EPIC scores. The median age at the time of prostate bed RT was 68.9 years, and patients were inquired about their QoL in the median 2.3 years after RT. The median pre-RT prostate-specific antigen (PSA) serum level was 0.35 ng/mL. The median duration between surgery and RT was 1.5 years. The median prescribed dose to the prostate bed was 72 Gy. A total of 61.6% received prostate bed RT only. For the bladder, the highest level of statistical correlation (p < 0.01) was seen for V10-20Gy, Dmean and Dmedian with urinary QoL. For bladder wall, the highest level of statistically significant correlation (p < 0.01) was seen for V5-25Gy, Dmean and Dmedian with urinary QoL. Penile bulb V70Gy was statistically significantly correlated with sexual QoL (p < 0.05). A larger rectal volume was significantly correlated with improved bowel QoL (p < 0.05). Sigmoid and urethral DVH parameters as well as the surgical approach were not statistically significantly correlated with QoL. Specific dose constraints for bladder volumes receiving low doses seem desirable for the further optimization of prostate bed RT. This may be particularly relevant in the context of the aspiration of establishing focal RT of prostate cancer and its local recurrences. Our comprehensive dataset may aid future researchers in achieving these goals.

Deep learning based automated delineation of the intraprostatic gross tumour volume in PSMA-PET for patients with primary prostate cancer

PurposeWith the increased use of focal radiation dose escalation for primary prostate cancer (PCa), accurate delineation of gross tumor volume (GTV) in prostate-specific membrane antigen PET (PSMA-PET) becomes crucial. Manual approaches are time-consuming and observer dependent. The purpose of this study was to create a deep learning model for the accurate delineation of the intraprostatic GTV in PSMA-PET. MethodsA 3D U-Net was trained on 128 different 18F-PSMA-1007 PET images from three different institutions. Testing was done on 52 patients including one independent internal cohort (Freiburg: n = 19) and three independent external cohorts (Dresden: n = 14 18F-PSMA-1007, Boston: Massachusetts General Hospital (MGH): n = 9 18F-DCFPyL-PSMA and Dana-Farber Cancer Institute (DFCI): n = 10 68Ga-PSMA-11). Expert contours were generated in consensus using a validated technique. CNN predictions were compared to expert contours using Dice similarity coefficient (DSC). Co-registered whole-mount histology was used for the internal testing cohort to assess sensitivity/specificity. ResultsMedian DSCs were Freiburg: 0.82 (IQR: 0.73–0.88), Dresden: 0.71 (IQR: 0.53–0.75), MGH: 0.80 (IQR: 0.64–0.83) and DFCI: 0.80 (IQR: 0.67–0.84), respectively. Median sensitivity for CNN and expert contours were 0.88 (IQR: 0.68–0.97) and 0.85 (IQR: 0.75–0.88) (p = 0.40), respectively. GTV volumes did not differ significantly (p > 0.1 for all comparisons). Median specificity of 0.83 (IQR: 0.57–0.97) and 0.88 (IQR: 0.69–0.98) were observed for CNN and expert contours (p = 0.014), respectively. CNN prediction took 3.81 seconds on average per patient. ConclusionThe CNN was trained and tested on internal and external datasets as well as histopathology reference, achieving a fast GTV segmentation for three PSMA-PET tracers with high diagnostic accuracy comparable to manual experts.

Effect of Different Antitumor Regimens on Incidence and Severity of Corona Virus Disease 2019 Pneumonia in Lung Cancer Patients: A Single-center Retrospective Study

Studies have shown that the incidence and severity of corona virus disease 2019 (COVID-19) in patients with lung cancer are higher than those in healthy people. At present, the main anti-tumor treatments for lung cancer include surgery, immunotherapy, chemotherapy, radiotherapy, targeted therapy and anti-angiogenesis therapy. While the effects of different anti-tumor treatments on the occurrence and severity of COVID-19 pneumonia are not uniform. Therefore, we aimed to describe clinical characteristics and antitumor therapy of patients with lung cancer and COVID-19 pneumonia, and examined risk factors for severity in this population. From December 1, 2022 to February 15, 2023, a retrospective study was conducted in 217 patients diagnosed with COVID-19 and pathologically confirmed lung cancer in the Jinling Hospital. We collected data about patients' clinical features, antitumor treatment regimen within 6 months, and the diagnosis and treatment of COVID-19. Risk factors for occurrence and severity of COVID-19 pneumonia were identified by univariable and multivariable Logistic regression models. (1) Among the 217 patients included, 51 (23.5%) developed COVID-19 pneumonia, of which 42 (82.4%) were classified as medium and 9 (17.6%) were classified as severe; (2) Univariate and multivariate analysis revealed overweight (OR=2.405, 95%CI: 1.095-5.286) and intrapulmonary focal radiotherapy (OR=2.977, 95%CI: 1.071-8.274) are risk factors for increasing occurrence of COVID-19 pneumonia, while other therapies are not; (3) Chronic obstructive pulmonary disease (COPD) history (OR=7.600, 95%CI: 1.430-40.387) was more likely to develop severe pneumonia and anti-tumor therapies such as intrapulmonary focal radiotherapy, chemotherapy, targeted therapy and immunotherapy did not increase severity. Intrapulmonary focal radiation therapy within 6 months increased the incidence of COVID-19 pneumonia, but did not increase the severity. However, there was no safety concern for chemotherapy, targeted therapy, surgery and immunotherapy.