Understanding the pharmacological properties of a metabolic PET tracer in prostate cancer.

Generally, solid tumors (>400 mm(3)) are inherently acidic, with more aggressive growth producing greater acidity. If the acidity could be targeted as a biomarker, it would provide a means to gauge the pace of tumor growth and degree of invasiveness, as well as providing a basis for predicting responses to pH-dependent chemotherapies. We have developed a (64)Cu pH (low) insertion peptide (pHLIP) for targeting, imaging, and quantifying acidic tumors by PET, and our findings reveal utility in assessing prostate tumors.

Noninvasive Imaging of PSMA in prostate tumors with (89)Zr-Labeled huJ591 engineered antibody fragments: the faster alternatives.

Engineered antibody fragments offer faster delivery with retained tumor specificity and rapid clearance from nontumor tissues. Here, we demonstrate that positron emission tomography (PET) based detection of prostate specific membrane antigen (PSMA) in prostatic tumor models using engineered bivalent antibodies built on single chain fragments (scFv) derived from the intact antibody, huJ591, offers similar tumor delineating properties but with the advantage of rapid targeting and imaging. (89)Zr-radiolabeled huJ591 scFv (dimeric scFv-CH3; (89)Zr-Mb) and cysteine diabodies (dimeric scFv; (89)Zr-Cys-Db) demonstrated internalization and similar Kds (∼2 nM) compared to (89)Zr-huJ591 in PSMA(+) cells.

Antagonism of EGFR and HER3 enhances the response to inhibitors of the PI3K-Akt pathway in triple-negative breast cancer.

Both abundant epidermal growth factor receptor (EGFR or ErbB1) and high activity of the phosphatidylinositol 3-kinase (PI3K)-Akt pathway are common and therapeutically targeted in triple-negative breast cancer (TNBC). However, activation of another EGFR family member [human epidermal growth factor receptor 3 (HER3) (or ErbB3)] may limit the antitumor effects of these drugs. We found that TNBC cell lines cultured with the EGFR or HER3 ligand EGF or heregulin, respectively, and treated with either an Akt inhibitor (GDC-0068) or a PI3K inhibitor (GDC-0941) had increased abundance and phosphorylation of HER3.

(18)F-labeled-bioorthogonal liposomes for in vivo targeting.

Liposomes are attractive vehicles for the controlled release of drugs and cytotoxins and have a long-standing history in medical research and clinical practice. In addition to established therapeutic indications, liposomes have several favorable properties for molecular imaging, including high stability and the ability to be labeled with radioisotopes, as well as paramagnetic and fluorescent contrast agents. However, long circulation times and difficulties in creating targeted liposomes have proven challenges for imaging.

Applying PET to broaden the diagnostic utility of the clinically validated CA19.9 serum biomarker for oncology.

Unlabelled: Despite their considerable advantages, many circulating biomarkers have well-documented limitations. One prominent shortcoming in oncology is a high frequency of false-positive indications for malignant disease in upfront diagnosis. Because one common cause of false positivism is biomarker production from benign disorders in unrelated host tissues, we hypothesized that probing the sites of biomarker secretion with an imaging tool could be a broadly useful strategy to deconvolute the meaning of foreboding but inconclusive circulating biomarker levels.