Design, synthesis, and biological evaluation of novel thiourea derivatives as small molecule inhibitors for prostate specific membrane antigen.

Prostate cancer (PCa) has emerged to be the second leading cause of cancer-related deaths in men. Molecular imaging of PCa using targeted radiopharmaceuticals specifically to PCa cells promises accurate staging of primary disease, detection of localized and metastasized tumours, and helps predict the progression of the disease. Glutamate urea heterodimers have been popularly used as high-affinity small molecules in the binding pockets of popular and well-characterized PCa biomarker, prostate specific membrane antigen (PSMA).

First-in-patient study of OTL78 for intraoperative fluorescence imaging of prostate-specific membrane antigen-positive prostate cancer: a single-arm, phase 2a, feasibility trial.

Background: Targeted real-time imaging during robot-assisted radical prostatectomy provides information on the localisation and extent of prostate cancer. We assessed the safety and feasibility of the prostate-specific membrane antigen (PSMA)-targeted fluorescent tracer OTL78 in patients with prostate cancer.

Methods: In this single-arm, phase 2a, feasibility trial with an adaptive design was carried out in The Netherlands Cancer Institute, Netherlands.

Targeted detection of cancer at the cellular level during biopsy by near-infrared confocal laser endomicroscopy.

Suspicious nodules detected by radiography are often investigated by biopsy, but the diagnostic yield of biopsies of small nodules is poor. Here we report a method-NIR-nCLE-to detect cancer at the cellular level in real-time during biopsy. This technology integrates a cancer-targeted near-infrared (NIR) tracer with a needle-based confocal laser endomicroscopy (nCLE) system modified to detect NIR signal.

Folate Receptor Beta Designates Immunosuppressive Tumor-Associated Myeloid Cells That Can Be Reprogrammed with Folate-Targeted Drugs.

Although immunotherapies of tumors have demonstrated promise for altering the progression of malignancies, immunotherapies have been limited by an immunosuppressive tumor microenvironment (TME) that prevents infiltrating immune cells from performing their anticancer functions. Prominent among immunosuppressive cells are myeloid-derived suppressor cells (MDSC) and tumor-associated macrophages (TAM) that inhibit T cells via release of immunosuppressive cytokines and engagement of checkpoint receptors. Here, we explore the properties of MDSCs and TAMs from freshly isolated mouse and human tumors and find that an immunosuppressive subset of these cells can be distinguished from the nonimmunosuppressive population by its upregulation of folate receptor beta (FRβ) within the TME and its restriction to the TME.

Evaluation of Novel Tumor-Targeted Near-Infrared Probe for Fluorescence-Guided Surgery of Cancer.

Because the most reliable therapy for cancer involves quantitative resection of all diseased tissue, considerable effort has been devoted to improving a surgeon's ability to locate and remove all malignant lesions. With the aid of improved optical imaging equipment, we and others have focused on developing tumor-targeted fluorescent dyes to selectively illuminate cancer nodules during surgery. We describe here the design, synthesis, optical properties, in vitro and in vivo tumor specificity/affinity, pharmacokinetics, preclinical toxicology, and some clinical application of a folate receptor (FR)-targeted NIR dye (OTL38) that concentrates specifically in cancer tissues and clears rapidly from healthy tissues.

Evaluation of Novel Prostate-Specific Membrane Antigen-Targeted Near-Infrared Imaging Agent for Fluorescence-Guided Surgery of Prostate Cancer.

Purpose: The ability to locate and remove all malignant lesions during radical prostatectomy leads not only to prevent biochemical recurrence (BCR) and possible side effects but also to improve the life expectancy of patients with prostate cancer. Fluorescence-guided surgery (FGS) has emerged as a technique that uses fluorescence to highlight cancerous cells and guide surgeons to resect tumors in real time. Thus, development of tumor-specific near-infrared (NIR) agents that target biomarkers solely expressed on prostate cancer cells will enable to assess negative tumor margins and affected lymph nodes.

Development of a Small Molecule Tubulysin B Conjugate for Treatment of Carbonic Anhydrase IX Receptor Expressing Cancers.

Carbonic anhydrase IX (CAIX) is a membrane-spanning zinc metalloenzyme that catalyzes the reversible consumption of CO and water to form H + HCO. Many human cancers upregulate CAIX to help control the pH in their hypoxic microenvironments. The consequent overexpression of CAIX on malignant cells and low expression on normal tissues render CAIX a particularly attractive target for small molecule inhibitors, antibody-drug conjugates, and ligand-targeted drugs.

An open label trial of folate receptor-targeted intraoperative molecular imaging to localize pulmonary squamous cell carcinomas.

Background: Clinical applicability of folate receptor-targeted intraoperative molecular imaging (FR-IMI) has been established for surgically resectable pulmonary adenocarcinoma. A role for FR-IMI in other lung cancer histologies has not been studied. In this study, we evaluate feasibility of FR-IMI in patients undergoing pulmonary resection for squamous cell carcinomas (SCCs).

Identification of a Folate Receptor-Targeted Near-Infrared Molecular Contrast Agent to Localize Pulmonary Adenocarcinomas.

Non-small cell lung cancer (NSCLC) is the number one cancer killer in the United States. Despite attempted curative surgical resection, nearly 40% of patients succumb to recurrent disease. High recurrence rates may be partially explained by data suggesting that 20% of NSCLC patients harbor synchronous disease that is missed during resection.

Intraoperative Molecular Imaging Combined With Positron Emission Tomography Improves Surgical Management of Peripheral Malignant Pulmonary Nodules.

Objective: To determine if intraoperative molecular imaging (IMI) can improve detection of malignant pulmonary nodules.

Background: 18-Fluorodeoxyglucose positron emission tomography (PET) is commonly utilized in preoperative assessment of patients with solid malignancies; however, false negatives and false positives remain major limitations. Using patients with pulmonary nodules as a study model, we hypothesized that IMI with a folate receptor targeted near-infrared contrast agent (OTL38) can improve malignant pulmonary nodule identification when combined with PET.

Comparison of Folate Receptor Targeted Optical Contrast Agents for Intraoperative Molecular Imaging.

Background. Intraoperative imaging can identify cancer cells in order to improve resection; thus fluorescent contrast agents have emerged. Our objective was to do a preclinical comparison of two fluorescent dyes, EC17 and OTL38, which both target folate receptor but have different fluorochromes.

A CXCR4-targeted site-specific antibody-drug conjugate.

A chemically defined anti-CXCR4-auristatin antibody-drug conjugate (ADC) was synthesized that selectively eliminates tumor cells overexpressing the CXCR4 receptor. The unnatural amino acid p-acetylphenylalanine (pAcF) was site-specifically incorporated into an anti-CXCR4 immunoglobulin G (IgG) and conjugated to an auristatin through a stable, non-cleavable oxime linkage to afford a chemically homogeneous ADC. The full-length anti-CXCR4 ADC was selectively cytotoxic to CXCR4(+) cancer cells in vitro (half maximal effective concentration (EC50 )≈80-100 pM).

Recruiting cytotoxic T cells to folate-receptor-positive cancer cells.

Herein, we describe the synthesis of a chemically defined anti-CD3 Fab-folate conjugate that targets cytotoxic T cells to folate receptor positive (FR) tumors. The unnatural amino acid pacetylphenylalanine (pAcPhe) was site-specifically incorporated into an anti-CD3 Fab and conjugated to folate via the formation of a stable oxime linkage. The anti-CD3 Fab-folate conjugate was able to promote T cell mediated killing of FR cancer cells in culture.

Synthesis and activity of a folate targeted monodisperse PEG camptothecin conjugate.

A folate targeted camptothecin small molecule drug conjugate (SMDC) was synthesized using a monodisperse PEG spacer linked to folate via a releasable disulfide carbonate linker. Cell cytotoxicity in human KB cells exhibited an IC50 of 6nM. Importantly, activity of the prodrug was blocked by excess folate, demonstrating receptor-mediated celluar uptake of the PEG conjugate.

Comparative analysis of folate derived PET imaging agents with [(18)F]-2-fluoro-2-deoxy-d-glucose using a rodent inflammatory paw model.

Activated macrophages play a significant role in initiation and progression of inflammatory diseases and may serve as the basis for the development of targeted diagnostic methods for imaging sites of inflammation. Folate receptor beta (FR-β) is differentially expressed on activated macrophages associated with inflammatory disease states yet is absent in either quiescent or resting macrophages. Because folate binds with high affinity to FR-β, development of folate directed imaging agents has proceeded rapidly in the past decade.

Development of tumor-targeted near infrared probes for fluorescence guided surgery.

Complete surgical resection of malignant disease is the only reliable method to cure cancer. Unfortunately, quantitative tumor resection is often limited by a surgeon's ability to locate all malignant disease and distinguish it from healthy tissue. Fluorescence-guided surgery has emerged as a tool to aid surgeons in the identification and removal of malignant lesions.

Evaluation of the novel folate receptor ligand [18F]fluoro-PEG-folate for macrophage targeting in a rat model of arthritis.

Introduction: Detection of (subclinical) synovitis is relevant for both early diagnosis and monitoring of therapy of rheumatoid arthritis (RA). Previously, the potential of imaging (sub)clinical arthritis was demonstrated by targeting the translocator protein in activated macrophages using (R)-[11C]PK11195 and positron emission tomography (PET). Images, however, also showed significant peri-articular background activity.

A folate receptor-α-specific ligand that targets cancer tissue and not sites of inflammation.

Unlabelled: Folic acid has been frequently exploited to target attached drugs to cells that overexpress a folate receptor (FR). Unfortunately, folic acid and folate-linked drugs bind equally well to both major isoforms of the FR-that is, FR-α, which is primarily expressed on malignant cells, and FR-β, which is upregulated on activated monocytes and macrophages. Because both major isoforms of FR can be expressed simultaneously in the same organism, folic acid cannot enable selective targeting of therapeutic and imaging agents to either tumor masses or sites of inflammation.

CXCR4 expression in prostate cancer progenitor cells.

Tumor progenitor cells represent a population of drug-resistant cells that can survive conventional chemotherapy and lead to tumor relapse. However, little is known of the role of tumor progenitors in prostate cancer metastasis. The studies reported herein show that the CXCR4/CXCL12 axis, a key regulator of tumor dissemination, plays a role in the maintenance of prostate cancer stem-like cells.

Characterization of in vivo disulfide-reduction mediated drug release in mouse kidneys.

Due to the overexpression of a folate receptor (FR) on many malignant cells, folate-targeted drugs have been developed to improve the cancer specificity of chemotherapeutic agents. Therapeutic index is further enhanced with the use of self-immolative linkers that efficiently release the attached drug upon cellular internalization of the folate-drug conjugate. Because FR is also abundant in normal kidney proximal tubule (PT) cells, we sought to examine in real time the trafficking and release of folate-targeted drugs in the kidney in vivo.

Synthesis and activity of folate conjugated didemnin B for potential treatment of inflammatory diseases.

A folate receptor targeted didemnin B conjugate was synthesized using a hydrophilic peptide spacer linked to folate via a releasable disulfide carbonate linker. Cell cytotoxicity and TNF-α inhibition in RAW264.7 macrophage-like cells exhibited IC(50)s of 13 and 5 nM, respectively.

Synthesis and biological analysis of prostate-specific membrane antigen-targeted anticancer prodrugs.

Ligand-targeted therapeutics have increased in prominence because of their potential for improved potency and reduced toxicity. However, with the advent of personalized medicine, a need for greater versatility in ligand-targeted drug design has emerged, where each tumor-targeting ligand should be capable of delivering a variety of therapeutic agents to the same tumor, each therapeutic agent being selected for its activity on a specific patient's cancer. In this report, we describe the use of a prostate-specific membrane antigen (PSMA)-targeting ligand to deliver multiple unrelated cytotoxic drugs to human prostate cancer (LNCaP) cells.

Bishydrazide glycoconjugates for lectin recognition and capture of bacterial pathogens.

Bishydrazides are versatile linkers for attaching glycans to substrates for lectin binding and pathogen detection schemes. The α,ω-bishydrazides of carboxymethylated hexa(ethylene glycol) (4) can be conjugated at one end to unprotected oligosaccharides, then attached onto carrier proteins, tethered onto activated carboxyl-terminated surfaces, or functionalized with a photoactive cross-linking agent for lithographic patterning. Glycoconjugates of bishydrazide 4 can also be converted into dithiocarbamates (DTCs) by treatment with CS(2) under mild conditions, for attachment onto gold substrates.

Deep-tissue imaging of intramolecular fluorescence resonance energy-transfer parameters.

We demonstrate the in vivo reconstruction of all fluorescence resonance energy transfer (FRET) parameters, including the nanometer donor-acceptor distance, in a mouse. The FRET chemical targets cancer cells, and on internalization, the acceptor is released, in lieu of a targeted anticancer drug in chemotherapy. Our method provides a new vehicle for studying disease by imaging FRET parameters in deep tissue.

Targeting of nanoparticles: folate receptor.

Nanoparticulate medicines offer the advantage of allowing delivery of large quantities of unmodified drug within the same particle. Nanoparticle uptake by cancer cells can, however, be compromised due to the large size and hydrophilicity of the particle. To circumvent cell penetration problems and simultaneously improve tumor specificity, nanoparticulate medicines have been linked to targeting ligands that bind to malignant cell surfaces and enter cells by receptor-mediated endocytosis.