Radiation-induced photodynamic therapy using calcium tungstate nanoparticles and 5-aminolevulinic acid prodrug.

Photodynamic therapy (PDT) using 5-aminolevulinic acid (ALA) prodrug is a clinically tried and proven treatment modality for surface-level lesions. However, its use for deep-seated tumors has been limited due to the poor penetration depth of visible light needed to activate the photosensitizer protoporphyrin IX (PPIX), which is produced from ALA metabolism. Herein, we report the usage of poly(ethylene glycol-b-lactic acid) (PEG-PLA)-encapsulated calcium tungstate (CaWO4, CWO for short) nanoparticles (PEG-PLA/CWO NPs) as energy transducers for X-ray-activated PDT using ALA. Owing to the spectral overlap between radioluminescence afforded by the CWO core and the absorbance of PPIX, these NPs can serve as an in situ visible light activation source during radiotherapy (RT), thereby mitigating the limitation of penetration depth. We demonstrate that this effect is observed across different cell lines with varying radio-sensitivity. Importantly, both PPIX and PEG-PLA/CWO NPs exhibit no significant toxicities at therapeutic doses in the absence of radiation. To assess the efficacy of this approach, we conducted a study using a syngeneic mouse model subcutaneously implanted with inherently radio-resistant 4T1 tumors. The results show a significantly improved prognosis compared to conventional RT, even with as few as 2 fractions of 4 Gy X-rays. Taken together, these results suggest that PEG-PLA/CWO NPs are promising agents for application of ALA-PDT in deep-seated tumors, thereby significantly expanding the utility of the already established treatment strategy.

BRD9 Is a Critical Regulator of Androgen Receptor Signaling and Prostate Cancer Progression.

Switch/sucrose-nonfermentable (SWI/SNF) chromatin-remodeling complexes are critical regulators of chromatin dynamics during transcription, DNA replication, and DNA repair. A recently identified SWI/SNF subcomplex termed GLTSCR1/1L-BAF (GBAF; or "noncanonical BAF", ncBAF) uniquely contains bromodomain-containing protein BRD9 and glioma tumor suppressor candidate region 1 (GLTSCR1) or its paralog GLTSCR1-like (GLTSCR1L). Recent studies have identified a unique dependency on GBAF (ncBAF) complexes in synovial sarcoma and malignant rhabdoid tumors, both of which possess aberrations in canonical BAF (cBAF) and Polybromo-BAF (PBAF) complexes. Dependencies on GBAF in malignancies without SWI/SNF aberrations, however, are less defined. Here, we show that GBAF, particularly its BRD9 subunit, is required for the viability of prostate cancer cell lines in vitro and for optimal xenograft tumor growth in vivo. BRD9 interacts with androgen receptor (AR) and CCCTC-binding factor (CTCF), and modulates AR-dependent gene expression. The GBAF complex exhibits overlapping genome localization and transcriptional targets as bromodomain and extraterminal domain-containing (BET) proteins, which are established AR coregulators. Our results demonstrate that GBAF is critical for coordinating SWI/SNF-BET cooperation and uncover a new druggable target for AR-positive prostate cancers, including those resistant to androgen deprivation or antiandrogen therapies. SIGNIFICANCE: Advanced prostate cancers resistant to androgen receptor antagonists are still susceptible to nontoxic BRD9 inhibitors, making them a promising alternative for halting AR signaling in progressed disease.

Bilirubin-Coated Radioluminescent Particles for Radiation-Induced Photodynamic Therapy.

Photodynamic therapy (PDT) has shown potential as a cancer treatment modality, but its clinical application is limited due to its visible-light activation since visible wavelengths of light cannot penetrate tissues well. Additionally, combination therapies utilizing PDT and radiotherapy have shown clinical promise in several cancers but are limited again by light penetration and the need for selective photosensitization of the treatment area. Herein, we report the development of bilirubin-photodynamic nanoparticles (PEGylated bilirubin-encapsulated CaWO4 nanoparticles or "PEG-BR/CWO NPs"). PEG-BR/CWO NPs are a formulation of PEGylated bilirubin micelles encapsulating CaWO4 nanoparticles. These particles are capable of activating PDT via X-ray irradiation within deep tissues due to the radioluminescence properties of their CaWO4 nanoparticle cores. PEG-BR/CWO NPs facilitate a combination of photodynamic and radiation therapy and represent a previously unexplored application of PEG-bilirubin conjugates as photosensitizing agents. When irradiated by X-rays, PEG-BR/CWO NPs emit UV-A and visible light from their CaWO4 cores, which excites bilirubin and leads to the production of singlet oxygen. PEG-BR/CWO NPs exhibit improvements over X-ray therapy alone in vitro and in murine xenograft models of head and neck cancer. The data presented in this study indicate that PEG-BR/CWO NPs are promising agents for facilitating combined radio-photodynamic therapy in deep tissue tumors.

Radioluminescent nanoparticles for radiation-controlled release of drugs.

The present work demonstrates a novel concept for intratumoral chemo-radio combination therapy for locally advanced solid tumors. For some locally advanced tumors, chemoradiation is currently standard of care. This combination treatment can cause acute and long term toxicity that can limit its use in older patients or those with multiple medical comorbidities. Intratumoral chemotherapy has the potential to address the problem of systemic toxicity that conventional chemotherapy suffers, and may, in our view, be a better strategy for treating certain locally advanced tumors. The present study proposes how intratumoral chemoradiation can be best implemented. The enabling concept is the use of a new chemotherapeutic formulation in which chemotherapy drugs (e.g., paclitaxel (PTX)) are co-encapsulated with radioluminecsnt nanoparticles (e.g., CaWO4 (CWO) nanoparticles (NPs)) within protective capsules formed by biocompatible/biodegradable polymers (e.g., poly(ethylene glycol)-poly(lactic acid) or PEG-PLA). This drug-loaded polymer-encapsulated radioluminescent nanoparticle system can be locally injected in solution form into the patient's tumor before the patient receives normal radiotherapy (e.g., 30-40 fractions of 2-3 Gy daily X-ray dose delivered over several weeks for locally advanced head and neck tumors). Under X-ray irradiation, the radioluminescent nanoparticles produce UV-A light that has a radio-sensitizing effect. These co-encapsulated radioluminescent nanoparticles also enable radiation-triggered release of chemo drugs from the polymer coating layer. The non-toxic nature (absence of dark toxicity) of this drug-loaded polymer-encapsulated radioluminescent nanoparticle ("PEG-PLA/CWO/PTX") formulation was confirmed by the MTT assay in cancer cell cultures. A clonogenic cell survival assay confirmed that these drug-loaded polymer-encapsulated radioluminescent nanoparticles significantly enhance the cancer cell killing effect of radiation therapy. In vivo study validated the efficacy of PEG-PLA/CWO/PTX-based intratumoral chemo-radio therapy in mouse tumor xenografts (in terms of tumor response and mouse survival). Results of a small-scale NP biodistribution (BD) study demonstrate that PEG-PLA/CWO/PTX NPs remained at the tumor sites for a long period of time (> 1 month) following direct intratumoral administration. A multi-compartmental pharmacokinetic model (with rate constants estimated from in vitro experiments) predicts that this radiation-controlled drug release technology enables significant improvements in the level and duration of drug availability within the tumor (throughout the typical length of radiation treatment, i.e., > 1 month) over conventional delivery systems (e.g., PEG-PLA micelles with no co-encapsulated CaWO4, or an organic liquid, e.g., a 50:50 mixture of Cremophor EL and ethanol, as in Taxol), while it is capable of maintaining the systemic level of the chemo drug far below the toxic threshold limit over the entire treatment period. This technology thus has the potential to offer a new therapeutic option that has not previously been available for patients excluded from conventional chemoradiation protocols.

Amino alkynylisoquinoline and alkynylnaphthyridine compounds potently inhibit acute myeloid leukemia proliferation in mice.

BACKGROUND: Acute myeloid leukemia (AML) remains one of the most lethal, rarely cured cancers, despite decades of active development of AML therapeutics. Currently, the 5-year survival of AML patients is about 30% and for elderly patients, the rate drops to <10%. About 30% of AML patients harbor an activating mutation in the tyrosine kinase domain (TKD) of Fms-Like Tyrosine kinase 3 (FLT3) or a FLT3 internal tandem duplication (FLT3-ITD). Inhibitors of FLT3, such as Rydapt that was recently approved by the FDA, have shown good initial response but patients often relapse due to secondary mutations in the FLT3 TKD, like D835Y and F691 L mutations. METHODS: Alkynyl aminoisoquinoline and naphthyridine compounds were synthesized via Sonogashira coupling. The compounds were evaluated for their in vitro and in vivo effects on leukemia growth. FINDINGS: The compounds inhibited FLT3 kinase activity at low nanomolar concentrations. The lead compound, HSN431, also inhibited Src kinase activity. The compounds potently inhibited the viability of MV4-11 and MOLM-14 AML cells with IC50 values <1 nM. Furthermore, the viability of drug-resistant AML cells harboring the D835Y and F691 L mutations were potently inhibited. In vivo efficacy studies in mice demonstrated that the compounds could drastically reduce AML proliferation in mice. INTERPRETATION: Compounds that inhibit FLT3 and downstream targets like Src (for example HSN431) are good leads for development as anti-AML agents. FUND: Purdue University, Purdue Institute for Drug Discovery (PIDD), Purdue University Center for Cancer Research, Elks Foundation and NIH P30 CA023168.

Folic Acid-Conjugated Radioluminescent Calcium Tungstate Nanoparticles as Radio-Sensitizers for Cancer Radiotherapy.

Radiation therapy is a primary treatment modality for many forms of cancer. Normally, the highest tolerable dose of ionizing radiation is used to treat tumors, but limitations imposed by normal tissue complications present challenges for local tumor control. In light of this, a class of compounds called radio-sensitizers have been developed to enhance the effectiveness of radiation. Many of these are small molecule drugs found to interact favorably with radiation therapy, but recent advances have been made using nanoparticles as radio-sensitizers. Herein, we report the utilization of radio-luminescent calcium tungstate nanoparticles that emit photoelectrons, UV-A, and visible light during X-ray irradiation, acting as effective radio-sensitizers ("Radio Luminescence Therapy"). In addition, a folic acid-functionalized form of these nanoparticles was shown to enhance radio-sensitization in vitro and in murine models of head and neck cancer. Folic acid-functionalized particles were found to decrease UV-A-induced clonogenic cell survival relative to nonfunctionalized particles. Several possible mechanisms were explored, and the folic acid-functionalized particles were found to mediate this increase in efficacy likely by activating pro-proliferative signaling through folate's innate mitogenic activity, leading to decreased repair of UV-A-induced DNA lesions. Finally, a clinical case study of a canine sarcoma patient demonstrated the initial safety and feasibility of translating these folic acid-functionalized particles into the clinic as radio-sensitizers in the treatment of spontaneous tumors.

Nontoxic Formulations of Scintillation Nanocrystals for Use as X-ray Computed Tomography Contrast Agents.

X-ray computed tomography (CT) is currently one of the most powerful, noninvasive, clinical in vivo imaging techniques, which has resulted from advances in both X-ray device and contrast enhancement technologies. The present study demonstrates, for the first time, that metal tungstates (such as CaWO4) are promising contrast agents for X-ray, radiation, and CT imaging, because of the high X-ray mass attenuation of tungsten (W). We have developed a method of formulation, in which CaWO4 (CWO) nanoparticles (NPs) are encapsulated within a biocompatible poly(ethylene glycol-b-d,l-lactic acid) (PEG-PLA) block copolymer (BCP) capsule. We show that these PEG-PLA-encapsulated CWO NPs (170 ± 10 nm hydrodynamic diameter) produce a higher CT contrast (by a factor of about 2) than commercial iodine-based radiocontrast agents (e.g., Iohexol) at identical molar concentrations of W or I atoms. PEG-PLA-coated CWO NPs are chemically stable and completely nontoxic. It was confirmed that the maximum tolerated dose (MTD) of this material in mice is significantly higher (250 ± 50 mg per kg body weight following a single intravenous (IV) administration) than, for instance, commercially available dextran-coated iron oxide nanoparticles that are currently used clinically as MRI contrast agents (MTD in mice ≈ 168 mg/kg per dose IV). IV-injected PEG-PLA/CWO NPs caused no histopathologic damage in major excretory organs (heart, liver, lungs, spleen, and kidney). When an IV dose of 100 mg/kg was given to mice, the blood circulation half-life was measured to be about 4 h, and more than 90% of the NPs were cleared from the mice within 24 h via the renal and hepatobiliary systems. When intratumorally administered, PEG-PLA-coated CWO NPs showed complete retention in a tumor-bearing mouse model (measurements were made up to 1 week). These results suggest that PEG-PLA-coated CWO NPs are promising materials for use in CT contrast.