HSA-ZW800-PEG for Enhanced Optophysical Stability and Tumor Targeting

Small molecule fluorophores often face challenges such as short blood half-life, limited physicochemical and optical stability, and poor pharmacokinetics. To overcome these limitations, we conjugated the zwitterionic near-infrared fluorophore ZW800-PEG to human serum albumin (HSA), creating HSA-ZW800-PEG. This conjugation notably improves chemical, physical, and optical stability under physiological conditions, addressing issues commonly encountered with small molecules in biological applications. Additionally, the high molecular weight and extinction coefficient of HSA-ZW800-PEG enhances biodistribution and tumor targeting through the enhanced permeability and retention effect. The unique distribution and elimination dynamics, along with the significantly extended blood half-life of HSA-ZW800-PEG, contribute to improved tumor targetability in both subcutaneous and orthotopic xenograft tumor-bearing animal models. This modification not only influences the pharmacokinetic profile, affecting retention time and clearance patterns, but also enhances bioavailability for targeting tissues. Our study guides further development and optimization of targeted imaging agents and drug-delivery systems.

Synthesis, Optical Properties, and In Vivo Biodistribution Performance of Polymethine Cyanine Fluorophores

Near-infrared (NIR) cyanine dyes showed enhanced properties for biomedical imaging. A systematic modification within the cyanine skeleton has been made through a facile design and synthetic route for optimal bioimaging. Herein, we report the synthesis of 11 NIR cyanine fluorophores and an investigation of their physicochemical properties, optical characteristics, photostability, and in vivo performance. All synthesized fluorophores absorb and emit within 610-817 nm in various solvents. These dyes also showed high molar extinction coefficients ranging from 27,000 to 270,000 cm-1 M-1, quantum yields 0.01 to 0.33, and molecular brightness 208-79,664 cm-1 M-1 in the tested solvents. Photostability data demonstrate that all tested fluorophores 28, 18, 20, 19, 25, and 24 are more photostable than the FDA-approved indocyanine green. In the biodistribution study, most compounds showed tissue-specific targeting to selectively accumulate in the adrenal glands, lymph nodes, or gallbladder while excreted to the hepatobiliary clearance route. Among the tested, compound 23 showed the best targetability to the bone marrow and lymph nodes. Since the safety of cyanine fluorophores is well established, rationally designed cyanine fluorophores established in the current study will expand an inventory of contrast agents for NIR imaging of not only normal tissues but also cancerous regions originating from these organs/tissues.

Ultralow Background Near-Infrared Fluorophores with Dual-Channel Intraoperative Imaging Capability

Two of the most pressing challenges facing bioimaging are nonspecific uptake of intravenously administered contrast agents and incomplete elimination of unbound targeted agents from the body. Designing a targeted contrast agent that shows fast clearance from background tissues and eventually the body after complete targeting is key to the success of image-guided interventions. Here, this work describes the development of renally clearable near-infrared contrast agents and their potential use for dual-channel image-guided tumor targeting. cRGD-ZW800-PEG (800 nm channel) and ZW700-PEG (700 nm channel) are able to visualize tumor margins and tumor vasculature simultaneously and respectively. These targeted agents show rapid elimination from the bloodstream, followed by renal clearance, which together significantly lower off-target background signals and potential toxicity. To demonstrate its applicability, this multispectral imaging is performed in various tumor-bearing animal models including lung cancer, pancreatic neuroendocrine tumors, breast, and ovarian cancer.

Optical Tissue Phantoms for Quantitative Evaluation of Surgical Imaging Devices

Optical tissue phantoms (OTPs) have been extensively applied to the evaluation of imaging systems and surgical training. Due to their human tissue-mimicking characteristics, OTPs can provide accurate optical feedback on the performance of image-guided surgical instruments, simulating the biological sizes and shapes of human organs, and preserving similar haptic responses of original tissues. This review summarizes the essential components of OTPs (i.e., matrix, scattering and absorbing agents, and fluorophores) and the various manufacturing methods currently used to create suitable tissue-mimicking phantoms. As photobleaching is a major challenge in OTP fabrication and its feedback accuracy, phantom photostability and how the photobleaching phenomenon can affect their optical properties are discussed. Consequently, the need for novel photostable OTPs for the quantitative evaluation of surgical imaging devices is emphasized.

Microwave-Assisted Synthesis of the Red-Shifted Pentamethine Tetrahydroxanthylium Core with Absorbance within the Near Infrared-II Window

Thirteen red-shifted pentamethine dimethyl and diethylamino tetrahydroxanthylium derivatives have been successfully synthesized via the microwave-assisted approach. The optimized conditions developed in the synthesis provided an excellent yield in expedited reaction time. These newly synthesized dyes show well-defined optical properties resulting from the diverse substitutions at the central meso positions. The majority of the compounds have a maximum wavelength of absorbance within 946-1022 nm with extinction coefficients in the range of 9700-110,680 M-1 cm-1 in various solvents such as MeOH, EtOH, DMSO, DCM, MeCN, and DMF. These fluorophores, to the best of our knowledge, are the first NIR-II small molecules synthesized using microwave chemistry. We also investigated these dyes for their NIR fluorescence imaging capabilities. Diethylamino-substituted compounds and bromination resulted in higher uptake in the adrenal gland compared to dimethylamino fluorophores. In addition, micellar structures of compounds 7 and 15 improved the targetability of the original dyes to the bone marrow, lymph nodes, and nerves. Overall, NIR-II imaging has the potential to visualize biologically targeted tissues in living organisms.

P800SO3-PEG: a renal clearable bone-targeted fluorophore for theranostic imaging

BACKGROUND

Due to the deep tissue penetration and reduced scattering, NIR-II fluorescence imaging is advantageous over conventional visible and NIR-I fluorescence imaging for the detection of bone growth, metabolism, metastasis, and other bone-related diseases.

METHODS

Bone-targeted heptamethine cyanine fluorophores were synthesized by substituting the meso-carbon with a sulfur atom, resulting in a bathochromic shift and increased fluorescence intensity. The physicochemical, optical, and thermal stability of newly synthesized bone-targeted NIR fluorophores was performed in aqueous solvents. Calcium binding, bone-specific targeting, biodistribution, pharmacokinetics, and 2D and 3D NIR imaging were performed in animal models.

RESULTS

The newly synthesized S-substituted heptamethine fluorophores demonstrated a high affinity for hydroxyapatite and calcium phosphate, which improved bone-specific targeting with signal-background ratios > 3.5. Particularly, P800SO3-PEG showed minimum nonspecific uptake, and most unbound molecules were excreted into the urinary bladder. Histological analyses demonstrated that P800SO3-PEG remained stable in the bone for over two weeks and was incorporated into bone matrices. Interestingly, the flexible thiol ethylene glycol linker on P800SO3-PEG induced a promising photothermal effect upon NIR laser irradiation, demonstrating potential theranostic imaging.

CONCLUSIONS

P800SO3-PEG shows a high affinity for bone tissues, deeper tissue imaging capabilities, minimum nonspecific uptake in the major organs, and photothermal effect upon laser irradiation, making it optimal for bone-targeted theranostic imaging.

QuatCy-I2 and MHI-I2 in Photodynamic Therapy

MHI-I₂ (1) and QuatCy-I₂ (2) were compared in terms of properties important for early-stage photodynamic therapy preclinical candidates. Thus, experiments were performed to monitor dark cytotoxicities, light/dark cytotoxicity ratios, selectivity of localization in tumors over other organs, and clearance from the plasma.

Genetic determinants of fetal opiate exposure and risk of neonatal abstinence syndrome: Knowledge deficits and prospects for future research

Opiate-dependent pregnant women receive opiate maintenance medications to prevent illicit use and withdrawal. Fetal opiate exposure causes central nervous system (CNS) alterations which manifest as postnatal physical withdrawal. The extensive variability in the Neonatal Abstinence Syndrome phenotype remains unexplained and may be related to variability in fetal exposure and response. Improved understanding of functionally significant genetic variants in pathways influencing placental opiate transfer and fetal response can lead to personalized maternal therapy and optimized neonatal outcomes.

Efficacy of three drugs for protecting against gentamicin-induced hair cell and hearing losses

BACKGROUND AND PURPOSE Exposure to an ototoxic level of an aminoglycoside can result in hearing loss. In this we study investigated the otoprotective efficacy of dexamethasone (DXM), melatonin (MLT) and tacrolimus (TCR) in gentamicin (GM)-treated animals and cultures. EXPERIMENTAL APPROACH Wistar rats were divided into controls (treated with saline); exposed to GM only (GM); and three GM-exposed groups treated with either DXM, MLT or TCR. Auditory function and cochlear surface preparations were studied. In vitro studies of oxidative stress, pro-inflammatory cytokine mRNA levels, the MAPK pathway and caspase-3 activation were performed in organ of Corti explants from 3-day-old rats. KEY RESULTS DXM, MLT and TCR decreased levels of reactive oxygen species in GM-exposed explants. The mRNA levels of TNF-α, IL-1β and TNF-receptor type 1 were significantly reduced in GM + DXM and GM + MLT groups. Phospho-p38 MAPK levels decreased in GM + MLT and GM + TCR groups, while JNK phosphorylation was reduced in GM + DXM and GM + MLT groups. Caspase-3 activation decreased in GM + DXM, GM + MLT and GM + TCR groups. These results were consistent with in vivo results. Local treatment of GM-exposed rat cochleae with either DXM, MLT or TCR preserved auditory function and prevented auditory hair cell loss. CONCLUSIONS AND IMPLICATIONS In organ of Corti explants, GM increased oxidative stress and initiated an inflammatory response that led to the activation of MAPKs and apoptosis of hair cells. The three compounds tested demonstrated otoprotective properties that could be beneficial in the treatment of ototoxicity-induced hearing loss.

S3-5: Next Generation Sequencing Reveals Co-Activating Events in the MAPK and P13K/AKT Pathways in Metastatic Triple Negative Breast Cancers

INTRODUCTION: The clinical application of next generation sequencing to comprehensively characterize groups of driving mutations in individual metastatic triple negative breast cancer (mTNBC) genomes has the potential to reveal therapeutically relevant pathway dependencies. Towards this end, we harvested tissue from 14 patients with mTNBC and are conducting deep whole genome and transcriptome sequencing for each case to identify mutations that can guide therapeutic targeting within available phase I/II clinical trials.

METHODS: Metastatic tumor tissue was harvested from 14 mTNBC patients, and 7 samples have undergone total genome and transcriptome sequencing with the others currently underway. We are utilizing the Life Technologies SOLiD® system to sequence germline and tumor DNA to sufficient depth to identify somatic genome alterations including point mutations, indels, and structural events including translocations. Furthermore, RNA-seq is being performed on these tumors, along with a series of age- and ethnicity-matched normal breast controls to perform deep differential expression analysis, isoform expression analysis, and fusion transcript detection. Our team of genome scientists and clinical oncologists are evaluating the sequencing findings and are prioritizing the investigational therapeutic options for each patient.

RESULTS: Our whole genome and transcriptome sequencing study has revealed numerous known and novel mutations in mTNBC. However, all patients’ cancers analyzed to date had alterations that would activate the MAPK pathway, but through various mechanisms in different patients. These include BRAF amplification and overexpression, NF1 homozygous deletion, and consistent IQGAP3 overexpression. Furthermore, all patients’ cancers also harbor mutations that would activate the PI3K/AKT pathway including PTEN homozygous deletion or down-regulation, consistent INPP4B down-regulation, FBXW7 homozygous deletion, and ERAS overexpression. Moreover, although we and others show ERBB4 down-regulation in breast tumors, we are the first to report unique somatic genomic events that significantly alter the ERBB4 locus leading to its loss in the majority (5/7) of our patients’ tumors. Importantly, we are beginning to use these insights to prioritize therapeutic targeting and have observed that one chemotherapy-refractory mTNBC patient, with a high-level BRAF amplification/overexpression along with down-regulation of PTEN and INPP4B, had a major response to combined mek plus akt inhibitors on a phase I study.

CONCLUSIONS: Comprehensive genomic and transcriptomic interrogation of mTNBCs has revealed events supporting co-activation of the MAPK and PI3K/AKT pathways in all the tumors albeit by different mutational mechanisms and supports potential effectiveness of combination therapy in the treatment of mTNBC. We plan to treat these patients with combined mek plus akt inhibitors on a new phase I study beginning in August 2011 to determine the effectiveness of co-inhibition of these pathways based on this frequent genomic context.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr S3-5.

Release rates of levonorgestrel from Silastic capsules, homogeneous rods and covered rods in humans

Three forms of subdermal implants containing levonorgestrel are described. These are: capsules, in which the powdered drug is sealed inside of lengths of Medical Grade Silastic tubing; homogeneous rods, in which the drug is uniformly dispersed in Silastic 382 Medical Grade Elastomer; and covered rods, in which a core rod of drug and filler-free polydimethylsiloxane polymer (50:50, Wt:Wt) are sealed inside thin-walled Silastic tubing. Long-term in vivo release rates from human subjects are presented; 6.5 years for capsules, 3.6 years for homogeneous rods and 4 years for covered rods. Sets of six capsules release a decreasing amount of drug through the first few hundred days in situ and after 500 days a fairly constant rate of about 35 micrograms per day is released (2 micrograms/cm). Homogeneous rods deliver a continuously declining amount of drug during the entire time studied. In the first 100 days the release averages 136 micrograms per day from a set of three 3-cm rods (15 micrograms/cm), gradually declining to 30 micrograms per day (3.3 micrograms/cm) from day 800 to day 1300. The covered rods deliver at a constant rate of 17.5 micrograms per day for a 3-cm rod (5.83 micrograms/cm) through 4 years.