Image-Based Quantification of Gold Nanoparticle Uptake and Localization in 3D Tumor Models to Inform Radiosensitization Schedule.

Gold nanoparticles (GNPs) have shown particular promise as radiosensitizing agents and as complementary drug delivery agents to improve therapeutic index in cancer treatment. Optimal implementation, however, depends critically on the localization of GNPs at the time of irradiation, which, in turn, depends on their size, shape, and chemical functionalization, as well as organism-level pharmacokinetics and interactions with the tumor microenvironment. Here, we use in vitro 3D cultures of A549 lung carcinoma cells, which recapitulate interaction with extracellular matrix (ECM) components, combined with quantitative fluorescence imaging to study how time-dependent localization of ultrasmall GNPs in tumors and ECM impacts the degree of damage enhancement to tumor cells. Confocal imaging of fluorescence-labeled GNPs in 3D culture reveals that nanoparticles are initially embedded in ECM and only gradually accumulate in cancer cells over multiple days. Furthermore, the timing of GNP redistribution from ECM to cellular compartments directly impacts efficacy, with major damage enhancement when irradiation is performed after GNPs have accumulated significantly in 3D tumor nodules. These results underscore the importance of the timing and scheduling in treatment planning to ensure optimal radiosensitization, as well as the necessity of studying these effects in model systems that recapitulate elements of tumor microenvironment interaction.

IRay therapy as an adjuvant therapy in newly diagnosed patients with neovascular age-related macular degeneration.

OBJECTIVES: To determine the safety and efficacy at 12 months of follow-up after stereotactic radiotherapy in combination therapy with intravitreal ranibizumab injections in treatment naïve patients with neovascular age-related macular degeneration. METHODS: Retrospective data analysis in patients who received stereotactic radiotherapy (IRay Therapy) during the induction phase of intravitreal ranibizumab injections and a monotherapy control group. RESULTS: The baseline VA in the IRay and control group was 59.87 and 59.12 letters respectively. The real world visual acuity outcomes for the IRay group showed a mean gain of +3.0 letters at 12 months. The historical control group had a mean change of - 0.3 letters. The average number of injections for the IRay group and control group over 12 months was 4.45 and 5.64, respectively with three loading injections. Excluding the loading phase, the difference over 12 months was a 45.2% reduction in injections (P < 0.001). The number of subjects in the IRay group that didn't require further injections following the loading phase was 45.5 vs. 24.0% control group (P = 0.005). The difference in mean change in central macular thickness from baseline is significant at 6 (P = 0.010) and 12 months (P < 0.01). There were no safety concerns with the IRay therapy group. CONCLUSIONS: Stereotactic radiotherapy in the induction phase of intravitreal injections of ranibizumab for treatment naïve patients with neovascular age-related macular degeneration, resulted in improved visual outcome, statistically fewer injections and statistically drier macular at 12 months, compared to historical controls treated with monotherapy intravitreal ranibizumab injections.

Stereotactic radiotherapy for wet age-related macular degeneration (INTREPID): influence of baseline characteristics on clinical response.

PURPOSE: To determine which patients respond best to stereotactic radiotherapy (SRT) for neovascular age-related macular degeneration. METHODS: Participants (n = 230) receiving intravitreal anti-vascular endothelial growth factor injections for neovascular age-related macular degeneration enrolled in a randomized, double-masked sham-controlled trial comparing 16 Gray, 24 Gray, or Sham SRT. In a post hoc analysis, participants were grouped according to their baseline characteristics, to determine if these influenced SRT efficacy. RESULTS: At 52 weeks, SRT was most effective for lesions ≤4 mm in greatest linear dimension and with a macular volume greater than the median value of 7.4 mm. For 26% of the participants with both these characteristics, SRT resulted in 55% fewer ranibizumab injections (2.08 vs. 4.60; P = 0.0002), a mean visual acuity change that was 5.33 letters superior to sham (+2.18 vs. -3.15 letters; P = 0.0284), and a 71.1-µm greater reduction in mean central subfield thickness (-122.6 vs. -51.5 µm; P = 0.027). Other features associated with a positive response to SRT included pigment epithelial detachment and the absence of fibrosis. CONCLUSION: Stereotactic radiotherapy is most effective for neovascular age-related macular degeneration lesions that are actively leaking at the time of treatment, and no larger than the 4-mm treatment zone.

Stereotactic radiotherapy for neovascular age-related macular degeneration: year 2 results of the INTREPID study.

PURPOSE: To determine the safety and efficacy of low-voltage, external-beam, stereotactic radiotherapy (SRT) for patients with neovascular age-related macular degeneration (AMD). DESIGN: Randomized, double-masked, sham-controlled, multicenter, clinical trial. PARTICIPANTS: A total of 230 participants with neovascular AMD who received ≥ 3 ranibizumab or bevacizumab injections within the preceding year and requiring treatment at enrollment. METHODS: Participants received 16 Gray, 24 Gray, or sham SRT. All arms received pro re nata (PRN) ranibizumab for 12 months, with PRN bevacizumab or ranibizumab thereafter. MAIN OUTCOME MEASURES: Mean number of PRN injections; best-corrected visual acuity (BCVA); loss of <15 Early Treatment of Diabetic Retinopathy Study letters; change in optical coherence tomography central subfield thickness; and change in angiographic total lesion area and choroidal neovascularization (CNV) area. RESULTS: At year 2, the 16 and 24 Gray arms received fewer PRN treatments compared with sham (mean 4.5, P = 0.008; mean 5.4, P = 0.09; and mean 6.6, respectively). Change in mean BCVA was -10.0, -7.5, and -6.7 letters for the 16 Gray, 24 Gray, and sham arms, respectively, with 46 (68%), 51 (75%), and 58 participants (79%), respectively, losing <15 letters. Mean central subfield thickness decreased by 67.0 µm, 55.4 µm, and 33.3 µm, respectively. Mean total active lesion area increased by 1.0, 4.2, and 2.7 mm(2), respectively. Mean CNV area decreased by 0.1 mm(2) in all groups. An independent reading center detected microvascular abnormalities in 6 control eyes and 29 SRT eyes, of which 18 were attributed to radiation; however, only 2 of these possibly affected vision. An exploratory subgroup analysis found that lesions with a greatest linear dimension ≤ 4 mm (the size of the treatment zone) and a macular volume greater than the median (7.4 mm(3)) were more responsive to SRT, with 3.9 PRN injections versus 7.1 in comparable sham-treated participants (P = 0.001) and mean BCVA 4.4 letters superior to sham (P = 0.24). CONCLUSIONS: A single dose of SRT significantly reduces intravitreal injections over 2 years. Radiation can induce microvascular change, but in only 1% of eyes does this possibly affect vision. The best response occurs when AMD lesions fit within the treatment zone and they are actively leaking.

Theory concerning the ablation of corneal tissue with large-area, 193-nm excimer laser beams.

Excimer laser beams (193 nm) of uniform fluence were studied to find out why they produce corneal ablations deeper at the edge than the center. Ablation depth profiles were taken of porcine corneas, including five dehydrated samples. Hydrated corneas and polymethyl methacrylate were ablated with and without central masks. Ablation plumes were photographed. Hydrated porcine corneas showed patterns of central underablation. As the incident beam increased, the crater exhibited increasingly shallower central ablation while maintaining nearly constant depth at the edges. Dehydrated corneas did not vary significantly. Masks did not alter the depth or shape of craters near ablation edges, but depth adjacent to the images of the masks was more than twice that with no mask. Depth adjacent to the mask image was nearly the same as at the edge of the zone. The rate of change in depth with position was nearly equal in both areas. Maximum plume density was centered over the entire ablation with and without the mask. Redeposition of plume particles is not the major cause of central underablation. Propagating transverse energy from the absorption of photons by peptide bonds increases pressure on excited components within the irradiated area, increasing recombination, which raises the ablation threshold.

Fluorescence-guided laser removal of chemically damaged cornea.

PURPOSE: To correlate the observed fluorescence spectrum with the depth of ablation during 193 nm argon-fluoride excimer laser ablation of chemically damaged corneas. SETTING: Laser facility, Cedars-Sinai Medical Center, Los Angeles, California, USA. METHODS: Three cadaver New Zealand white rabbit corneas were exposed to 1 N hydrogen chloride for 10 seconds. The resultant opaque corneas were ablated to perforation using the excimer laser. Laser-induced fluorescence was collected at 45 degrees from incidence and channeled into an ultraviolet-visible spectrometer coupled to an optical multichannel analyzer reading a diode array detector. The detector recorded single-shot fluorescence spectra. The data were examined by principal component analysis, and the evolution of eigenvectors and their weighting coefficients were used to compare data among corneas. The results were correlated with histopathological sections. RESULTS: The eigenvalues of 3 principal components corresponded to 88.9%, 10.0%, and 0.4% of the data in acid-burned corneas. Compared to that in undamaged corneas, more information was stored in the first principal component and the third eigenvector was distinctly altered. Acid-scarred tissue blue shifted the dominant fluorescence peak compared to that in normal corneal tissue. CONCLUSIONS: After severe hydrogen chloride burn to the rabbit corneal surface, monitoring the dominant peak wavelength shift of excimer-laser-induced fluorescence can detect the transition between severely acid-damaged and underlying tissue.

Fluorescencia inducida por el láser éxcimer (193 nm) en córneas cadavéricas de conejos / 193 nm excimer laser-induced fluoscence in rabbit cadaveric corneas

Observar la fluorescencia durante la ablación pulsada con láser éxcimer en córneas cadavéricas de conejos. Se expusieron 4 córneas cadavéricas de conejo a la energía del láser éxcimer de ArF a 1= 193nm. La fluorescencia resultante se registró a 45º de la incidencia del rayo y fue canalizada por un espectrómetro conectado a un analizador óptico multicanal capaz de leer un detector de diodo. La ablación continuó hasta la perforación. Los espectros obtenidos fueron sometidos a análisis por componentes principales (ACP). Se registraron los espectros del epitelio al endotelio. Se observaron cambios de espectros a medida que la ablación progresó. se evidenció una disminución obvia del pico de longitud de onda más corta a 367 nm. El ACP reveló que el espectro era consistente con datos obtenidos en córneas de humanos. Los resultados obtenidos pueden contribuir al conocimiento de los procesos que ocurren durante la ablación clínica con el láser éxcimer