A Multi-Institutional Study of Magnetic Resonance/Ultrasound Fusion-Guided Nanoparticle-Directed Focal Therapy for Prostate Ablation.

PURPOSE: Focal therapy aims to provide a durable oncologic treatment option for men with prostate cancer (PCa), while preserving their quality of life. Most focal therapy modalities rely on the direct tissue effect, resulting in a possible nontargeted approach to ablation. Here, we report the results of the first human feasibility trial utilizing nanoparticle-directed focal photothermal ablation for PCa. MATERIALS AND METHODS: A prospective, open-label, single-arm, multicenter study of men with localized PCa in Gleason Grade Group 1 to 3 was conducted. Men received a single infusion of gold nanoparticles (AuroShells), followed by magnetic resonance (MR)/ultrasound (US) fusion-guided laser excitation of the target tissue to induce photothermal ablation. MRI was used to assess the effectiveness of prostate tissue ablation at 48 to 96 hours, 3 months, and 12 months post treatment. At 3 months, a targeted fusion biopsy of the lesion(s) was conducted. At 12 months, a targeted fusion biopsy and standard templated biopsy were performed. Treatment success was determined based on a negative MR/US fusion biopsy outcome within the treated area. RESULTS: Forty-six men were enrolled in the study, and 44 men with 45 lesions completed nanoparticle infusion and laser treatment. The mean PSA level at baseline was 9.5 ng/mL, which decreased to 5.9 ng/mL at 3 months and to 4.7 ng/mL at 12 months (P < .0001). The oncologic success rates at 3 and 12 months resulted in 29 (66%) and 32 (73%) of 44 patients, respectively, being successfully treated, confirmed with negative MR/US fusion biopsies within the ablation zone. Among Gleason Grade Group, maximum lesion diameter on MRI, prostate volume, and Prostate Imaging Reporting and Data System scoring, the maximum lesion diameter was significantly associated with the odds of treatment failure at 12 months (P = .046). CONCLUSIONS: Nanoparticle-directed focal laser ablation of neoplastic prostate tissue resulted in 73% of patients with successful treatment at 12 months post treatment, confirmed by negative MR/US fusion biopsy of the treated lesion and a systematic biopsy. CLINICAL TRIAL REGISTRATION NO.: 02680535.

A Detailed Clinical Case of Localized Prostate Tumors Treated with Nanoparticle-Assisted Sub-Ablative Laser Ablation.

AuroLase® Therapy-a nanoparticle-enabled focal therapy-has the potential to safely and effectively treat localized prostate cancer (PCa), preserving baseline functionality. This article presents a detailed case of localized PCa treated with AuroLase, providing insight on expectations from the diagnosis of PCa to one year post-treatment. AuroLase Therapy is a two-day treatment consisting of a systemic infusion of gold nanoshells (~150-nm hydrodynamic diameter) on Day 1, and sub-ablative laser treatment on Day 2. Multiparametric MRI (mpMRI) was used for tumor visualization, treatment planning, and therapy response assessment. The PCa was targeted with a MR/Ultrasound-fusion (MR/US) transperineal approach. Successful treatment was confirmed at 6 and 12 months post-treatment by the absence of disease in MR/US targeted biopsies. On the mpMRI, confined void space was evident, an indication of necrotic tissues encompassing the treated lesion, which was completely resolved at 12 months, forming a band-like scar with no evidence of recurrent tumor. The patient's urinary and sexual functions were unchanged. During the one-year follow-up, changes on the DCE sequence and in the Ktrans and ADC values assist in qualitatively and quantitatively evaluating tissue changes. The results highlight the potential of gold-nanoparticle-enabled sub-ablative laser treatment to target and control localized PCa, maintain quality of life, and preserve baseline functionality.

Gd2O3-mesoporous silica/gold nanoshells: A potential dual T1/T2 contrast agent for MRI-guided localized near-IR photothermal therapy.

A promising clinical trial utilizing gold-silica core-shell nanostructures coated with polyethylene glycol (PEG) has been reported for near-infrared (NIR) photothermal therapy (PTT) of prostate cancer. The next critical step for PTT is the visualization of therapeutically relevant nanoshell (NS) concentrations at the tumor site. Here we report the synthesis of PEGylated Gd2O3-mesoporous silica/gold core/shell NSs (Gd2O3-MS NSs) with NIR photothermal properties that also supply sufficient MRI contrast to be visualized at therapeutic doses (≥108 NSs per milliliter). The nanoparticles have r1 relaxivities more than three times larger than those of conventional T1 contrast agents, requiring less concentration of Gd3+ to observe an equivalent signal enhancement in T1-weighted MR images. Furthermore, Gd2O3-MS NS nanoparticles have r2 relaxivities comparable to those of existing T2 contrast agents, observed in agarose phantoms. This highly unusual combination of simultaneous T1 and T2 contrast allows for MRI enhancement through different approaches. As a rudimentary example, we demonstrate T1/T2 ratio MR images with sixfold contrast signal enhancement relative to its T1 MRI and induced temperature increases of 20 to 55 °C under clinical illumination conditions. These nanoparticles facilitate MRI-guided PTT while providing real-time temperature feedback through thermal MRI mapping.

Plasmonic gadolinium oxide nanomatryoshkas: bifunctional magnetic resonance imaging enhancers for photothermal cancer therapy.

Nanoparticle-assisted laser-induced photothermal therapy (PTT) is a promising method for cancer treatment; yet, visualization of nanoparticle uptake and photothermal response remain a critical challenge. Here, we report a magnetic resonance imaging-active nanomatryoshka (Gd2O3-NM), a multilayered (Au core/Gd2O3 shell/Au shell) sub-100 nm nanoparticle capable of combining T1 MRI contrast with PTT. This bifunctional nanoparticle demonstrates an r1 of 1.28 × 108 mM-1 s-1, an MRI contrast enhancement per nanoparticle sufficient for T1 imaging in addition to tumor ablation. Gd2O3-NM also shows excellent stability in an acidic environment, retaining 99% of the internal Gd(3). This report details the synthesis and characterization of a promising system for combined theranostic nanoparticle tracking and PTT.

Skewness Analysis in Variance Spectroscopy Measures Nanoparticle Individualization.

An important enabling step in nanoparticle studies is the sorting of heterogeneous mixtures to prepare structurally homogeneous samples. It is also necessary to detect and monitor aggregation of the individual nanoparticles. Although variance spectroscopy provides a simple optical method for finding low concentrations of heteroaggregates in samples such as single-walled carbon nanotube dispersions, it cannot detect the homoaggregates that are relevant for well-sorted samples. Here we demonstrate that variance spectral data can be further analyzed to find third moments of intensity distributions (skewness), which reveal the presence of emissive homoaggregates. Using experimental measurements on variously processed nanotube dispersions, we deduce a simple numerical standard for recognizing aggregation in the highly sorted samples that are increasingly available to nanoscience researchers.

(n,m)-Specific Absorption Cross Sections of Single-Walled Carbon Nanotubes Measured by Variance Spectroscopy.

A new method based on variance spectroscopy has enabled the determination of absolute absorption cross sections for the first electronic transition of 12 (n,m) structural species of semiconducting single-walled carbon nanotubes (SWCNTs). Spectrally resolved measurements of fluorescence variance in dilute bulk samples provided particle number concentrations of specific SWCNT species. These values were converted to carbon concentrations and correlated with resonant components in the absorbance spectrum to deduce (n,m)-specific absorption cross sections (absorptivities) for nanotubes ranging in diameter from 0.69 to 1.03 nm. The measured cross sections per atom tend to vary inversely with nanotube diameter and are slightly greater for structures of mod 1 type than for mod 2. Directly measured and extrapolated values are now available to support quantitative analysis of SWCNT samples through absorption spectroscopy.

Resonance Raman Optical Activity Spectra of Single-Walled Carbon Nanotube Enantiomers.

We present experimental Raman optical activity (ROA) spectra of enantio-enriched single-walled carbon nanotubes (SWCNTs). Enantiomeric samples of (6,5) SWCNTs were prepared using nonlinear density gradient ultracentrifugation (DGU). Upon excitation at 2.33 eV, remarkably strong G-band signals are obtained due to strong resonance enhancement with the E22(S) transition of (6,5) SWCNTs. Enhancement allows measuring the vibrational optical activity (VOA) at unusually low concentrations. The obtained results are in good agreement with the single-excited-state theory (SES). To our knowledge, these are the first experimental VOA spectra of SWCNTs.

High precision fractionator for use with density gradient ultracentrifugation.

The recent application of density gradient ultracentrifugation (DGU) for structural sorting of single-walled carbon nanotube samples has created a need for highly selective extraction of closely spaced layers formed in the centrifuged tube. We describe a novel computer-controlled device designed for this purpose. Through the use of fine needles, systematic needle motions, and slow flow rates, multiple sample layers can be aspirated under program control with minimal cross contamination between layers. The fractionator's performance is illustrated with DGU-sorted samples of single-walled carbon nanotubes.