Biomimetic Nanovesicle with Mitochondria-Synthesized Sonosensitizer and Mitophagy Inhibition for Cancer Sono-Immunotherapy.

Mitochondria are crucial for both sonodynamic therapy and antitumor immunity. However, how to accurately damage mitochondria and meanwhile prevent the mitophagy and immune checkpoint inhibition is still a great challenge. Herein, hexyl 5-aminolevulinate hydrochloride (HAL) and 3-methyladenine (3MA) are loaded into the tumor cell-derived microparticle (X-MP), which can direct the target delivery of the prepared HAL/3MA@X-MP to the tumor cells. HAL induces the confined biosynthesis and accumulation of sonosensitizer PpIX in mitochondria, leading to the localized generation of reactive oxygen species (ROS) upon ultrasound irradiation and, thus, the efficient mitochondrial damage. Meanwhile, 3MA not only inhibits mitophagy but also down-regulates the PD-L1 expression, promoting the immunogenic cell death (ICD) while blocking the immune checkpoint recognition. The smart synergism of precise mitochondrial damage, mitophagy inhibition and antitumor immunity results in potent therapeutic efficacy without obvious side effects.

Smart Tumor-Cell-Derived Microparticles Provide On-Demand Photosensitizer Synthesis and Hypoxia Relief for Photodynamic Therapy.

Positioning essential elements of photodynamic therapy (PDT) near to mitochondria can conquer the rigorous spatiotemporal limitations of reactive oxygen species (ROS) transfer and make considerable differences in PDT. However, precise accumulation of photosensitizer (PS) and oxygen within mitochondria is still challenging. We simultaneously encapsulated hexyl 5-aminolevulinate hydrochloride (HAL) and 3-bromopyruvic acid (3BP) into microparticles collected from X-ray-irradiated tumor cells (X-MP). After systemic administration, the developed HAL/3BP@X-MP can specifically target and recognize tumor cells, where HAL induces efficient accumulation of PpIX in mitochondria via the intrinsic haem biosynthetic pathway. Meanwhile, 3BP remarkably increases the oxygen supply by inhibiting mitochondrial respiration. The accurate co-localization and prompt encounter of PpIX and oxygen produce sufficient ROS to directly disrupt mitochondria, resulting in significantly improved PDT outcomes.

Initial clinical experience of surface guided stereotactic radiation therapy with open-face mask immobilization for improving setup accuracy: a retrospective study.

PURPOSE: To propose a specific surface guided stereotactic radiotherapy (SRT) treatment procedure with open-face mask immobilization and evaluate the initial clinical experience in improving setup accuracy. METHODS AND MATERIALS: The treatment records of 48 SRT patients with head lesions were retrospectively analyzed. For each patient, head immobilization was achieved with a double-shell open-face mask. The anterior shell was left open to expose the forehead, nose, eyes and cheekbones. The exposed facial area was used as region-of-interest for surface tracking by AlignRT (VisionRT Inc, UK). The posterior shell provided a sturdy and personalized headrest. Patient initial setup was guided by 6DoF real-time deltas (RTD) using the reference surface obtained from the skin contour delineated on the planning CT images. The endpoint of initial setup was 1 mm in translational RTD and 1 degree in rotational RTD. CBCT guidance was performed to derive the initial setup errors, and couch shifts for setup correction were applied prior to treatment delivery. CBCT couch shifts, AlignRT RTD values, repositioning rate and setup time were analyzed. RESULTS: The absolute values of median (maximal) CBCT couch shifts were 0.4 (1.3) mm in VRT, 0.1 (2.5) mm in LNG, 0.2 (1.6) mm in LAT, 0.1(1.2) degree in YAW, 0.2 (1.4) degree in PITCH and 0.1(1.3) degree in ROLL. The couch shifts and AlignRT RTD values exhibited highly agreement except in VRT and PITCH (p value < 0.01), of which the differences were as small as negligible. We did not find any case of patient repositioning that was due to out-of-tolerance setup errors, i.e., 3 mm and 2 degree. The surface guided setup time ranged from 52 to 174 s, and the mean and median time was 97.72 s and 94 s respectively. CONCLUSIONS: The proposed surface guided SRT procedure with open-face mask immobilization is a step forward in improving patient comfort and positioning accuracy in the same process. Minimized initial setup errors and repositioning rate had been achieved with reasonably efficiency for routine clinical practice.

Development and Longitudinal Analysis of Plan-Based Streamlined Quality Assurance on Multiple Positioning Guidance Systems With Single Phantom Setup.

PURPOSE: This study was to propose and validate an efficient and streamlined quality assurance (QA) method with a single phantom setup to check performances of patient positioning guidance systems including six-degree-of-freedom (6DoF) couch, X-ray modalities (kV-kV, MV-MV and CBCT), optical surface imaging system (AlignRT), lasers and optical distance indicator (ODI). METHODS AND MATERIALS: The QA method was based on a pseudo-patient treatment plan using the AlignRT cube phantom. The cube was first randomly set up on the couch, and the initial position offsets were acquired by AlignRT and CBCT. The cube was restored to its reference position by 6DoF couch shift, during which the couch motion accuracy and tracking performances of AlignRT and CBCT were derived. After that, the residual offsets were acquired by kV-kV, MV-MV and AlignRT to derive the isocenter discrepancies. Finally, the laser alignment and ODI values were visually inspected. The QA procedure had been internally approved as a standard weekly QA test, and the results over 50 weeks were longitudinally analyzed for clinical validation. RESULTS: The 6DoF couch motion errors as well as the tracking errors of AlignRT were sub-millimeter and sub-degree, and no deviation over 1 mm or 1 deg was identified. The ROI mode of isocenter (ISO) in AlignRT exhibited more consistent results than the centroid (CEN). While the isocenter discrepancy between CBCT and kV-kV was negligible, the maximal discrepancies between CBCT and MV-MV were 0.4 mm in LNG and 0.3 deg in PITCH. The isocenter discrepancies between CBCT and AlignRT were <0.5 mm in translation and <0.3 deg in rotation. For AlignRT, the isocenter discrepancies between the DICOM and SGRT references were about 0.6 mm in VRT, 0.5 mm in LNG and 0.2 deg in PITCH. As the therapists became familiar with the workflow, the average time to complete the whole procedure was around 23 min. CONCLUSIONS: The streamlined QA exhibits desirable practicality as an efficient multipurpose performance check on positioning guidance systems. The stability, tracking performance and isocenter congruence of the positioning guidance systems have been fully validated for all clinical image guidance RT application, even SRS/SBRT, which requires the strictest tolerance.

Combination of radiotherapy and suppression of Tregs enhances abscopal antitumor effect and inhibits metastasis in rectal cancer.

BACKGROUND: Distant metastasis is the major cause of mortality in patients with locally advanced rectal cancer (LARC) following neoadjuvant chemoradiotherapy. Local radiotherapy can trigger an abscopal response to metastatic tumor cells. However, the abscopal effect is a rare event. CD4+ regulatory T (Treg) cell is a highly immune-suppressive subset which impedes immune surveillance against cancer, prevents the development of effective antitumor immunity and promotes tumor progression. We assume that the exploitation of the proimmunogenic effects of radiotherapy with anti-CD25 or anti-Cytotoxic T-Lymphocyte Associated Protein 4 (anti-CTLA4) monoclonal antibodies (mAbs) may enhance the local and abscopal effects in rectal cancer and improve the therapeutic outcome. METHODS: mRNA expression profiling of 81 pretreatment biopsy samples from LARC patients who received neoadjuvant radiotherapy (nRT) was performed to analyze the correlation between gene expression and prognosis. A retrospective analysis of patients with rectal cancer with distant metastasis or synchronous extracolonic cancers was performed to evaluate the abscopal effect of radiotherapy on rectal cancer. Two different dual-tumor mouse models were established to investigate the efficacy of single dose and dose-fractionated radiotherapy combined with anti-CD25 or anti-CTLA4 and anti-Programmed cell death 1 ligand 1 (anti-PD1) mAbs on the local tumor growth and liver metastasis. The univariate Cox regression analysis, one-way analysis of variance, Dunnett's test, a mixed-effect linear model and Kaplan-Meier survival analysis were used to calculate p values. RESULTS: The proportion of Tregs in pre-nRT biopsies was negatively correlated with prognosis (p=0.007). The retrospective analysis showed that regressing liver metastases were infiltrated by CD8+ T cells. In contrast, stable/progressing metastases and synchronous extracolonic cancers were characterized by PD1+ T cells and Tregs infiltration. Animal experiment results demonstrated that the combination of radiotherapy and anti-CD25/CTLA4 mAb resulted in a significant increase in CD8+ T cells and CD8+/CD4+ ratio in primary and secondary tumors compared with the irradiation alone group (all p<0.05 or p<0.01). The combined treatment was able to decrease Tregs, PD1+CD8+ and PD1+CD4+ T cells (p<0.05), suppress locally irradiated and distal unirradiated tumor growth, and improve overall survival rate. Radiotherapy in conjunction with anti-CTLA4 reduced liver metastasis (p<0.05). CONCLUSIONS: These data indicated that radiotherapy plus depletion of Tregs was able to improve the antitumor response and generate an abscopal effect.