Correction to: Metabolic relevance for N-hydroxy L-arginine reduction in estrogen-negative breast cancer cells.

We found a unit error with our LC-MS lower limit of quantitation (LLOQ) measurement in the Amino Acids Journal.

Metabolic relevance for N-hydroxy L-arginine reduction in estrogen-negative breast cancer cells.

We had shown Nw-hydroxy-L-arginine (NOHA) as a promising blood-based biomarker for estrogen-receptor-negative (ER-) breast cancer (BC) that differentiates ER- BC based on grade and molecular phenotype. In this in vitro study, we assessed the metabolic relevance for ER- BC-specific NOHA modulation and correlated them with NOHA regulatory responses. This study aids future NOHA clinical utility in ER- BC diagnosis and therapy management and would prove useful for potential drug discovery and development process.

Assessing N w-hydroxy-L-arginine applicability as a novel ethnic specific estrogen-negative breast cancer marker.

In our prior study we identified N w-hydroxy-L-arginine (NOHA) as a simple, yet sensitive indicator for estrogen negative (ER-) breast cancer early-prognosis, but not estrogen positive (ER+), and to offer ethnic selectivity for ER- detection. However, the ability of NOHA to assess ER- breast tumor based on disease progression, and tumor severity needs further delineation. Also, the overall NOHA storage stability needs to be validated. To assess the NOHA predictive capability based on disease progression, ER-/ER+ 3D-spheroids (from breast tumor cell lines of human origin) were cultured for 10 weeks. We found only ER- 3D-spheroid cultured for 10 weeks to show a gradual reduction in NOHA (both in culture medium and 3D-spheroid lysates) that correlated with a progressive increase in cellular NOS2 expression and NOS2 activity (measured as total nitrites). We additionally identified the NOHA-NOS2 correlation to be ethnically selective between ER- African American versus ER- Caucasian groups. Interestingly, such NOHA reduction was observed earlier in ER- culture medium (viz., after week 1) than from ER- 3D-spheroids lysates (viz., at the end of 3 weeks). When categorized based on 3D-spheroid grade, we found a ≥ 68% NOHA reduction in ER- spheroids that were ≤ 3 weeks old, that was categorized as "low-grade" (based on tumor size ≤ 250 µm, and with cellular characteristics identical to healthy cells). A substantial reduction in NOHA of ≥ 87% occurred with ER- 3D-spheroids grown for 6 weeks, which were categorized as "intermediate-grade" (with tumor size of ≥ 400 µm, and with less characteristic similarity to control spheroids). These in vitro findings thus suggest a distinct correlation between NOHA reduction and ER- tumor grade. Such distinctive correlation between NOHA and ER- tumor grade was additionally observed in de-identified clinical samples where a onefold higher reduction in NOHA occurred in grade-2 than with grade-1 de-identified patient plasma (when compared with control), and such correlation offered ethnic selectivity between ER- African American and ER- Caucasian groups. Of additional interest, when NOHA overall storage stability was assessed by incubating patient plasma and culture medium spiked with 75 pg/ml NOHA at multiple incubation temperatures and time-points, we found NOHA to maintain its stability for up to 6 weeks in culture medium and for 7 days in plasma at 4 °C and below. These results thus provide the first evidence of NOHA as a stable indicator to monitor ER- disease progression and tumor severity in ethnically distinctive populations.

Synthesis and in Vitro and in Vivo Evaluation of Phosphoinositide-3-kinase Inhibitors.

Phospoinositide-3-kinases (PI3K) are important oncology targets due to the deregulation of this signaling pathway in a wide variety of human cancers. A series of 2-morpholino, 4-substituted, 6-(3-hydroxyphenyl) pyrimidines have been reported as potent inhibitors of PI3Ks. Herein, we describe the structure-guided optimization of these pyrimidines with a focus on replacing the phenol moiety, while maintaining potent target inhibition and improving in vivo properties. A series of 2-morpholino, 4-substituted, 6-heterocyclic pyrimidines, which potently inhibit PI3K, were discovered. Within this series a compound, 17, was identified with suitable pharmacokinetic (PK) properties, which allowed for the establishment of a PI3K PK/pharmacodynamic-efficacy relationship as determined by in vivo inhibition of AKT(Ser473) phosphorylation and tumor growth inhibition in a mouse A2780 tumor xenograft model.

Identification of NVP-BKM120 as a Potent, Selective, Orally Bioavailable Class I PI3 Kinase Inhibitor for Treating Cancer.

Phosphoinositide-3-kinases (PI3Ks) are important oncology targets due to the deregulation of this signaling pathway in a wide variety of human cancers. Herein we describe the structure guided optimization of a series of 2-morpholino, 4-substituted, 6-heterocyclic pyrimidines where the pharmacokinetic properties were improved by modulating the electronics of the 6-position heterocycle, and the overall druglike properties were fine-tuned further by modification of the 4-position substituent. The resulting 2,4-bismorpholino 6-heterocyclic pyrimidines are potent class I PI3K inhibitors showing mechanism modulation in PI3K dependent cell lines and in vivo efficacy in tumor xenograft models with PI3K pathway deregulation (A2780 ovarian and U87MG glioma). These efforts culminated in the discovery of 15 (NVP-BKM120), currently in Phase II clinical trials for the treatment of cancer.

Design, structure-activity relationships and in vivo characterization of 4-amino-3-benzimidazol-2-ylhydroquinolin-2-ones: a novel class of receptor tyrosine kinase inhibitors.

The inhibition of key receptor tyrosine kinases (RTKs) that are implicated in tumor vasculature formation and maintenance, as well as tumor progression and metastasis, has been a major focus in oncology research over the last several years. Many potent small molecule inhibitors of vascular endothelial growth factor receptor (VEGFR) and platelet-derived growth factor receptor (PDGFR) kinases have been evaluated. More recently, compounds that act through the complex inhibition of multiple kinase targets have been reported and may exhibit improved clinical efficacy. We report herein a series of potent, orally efficacious 4-amino-3-benzimidazol-2-ylhydroquinolin-2-one analogues as inhibitors of VEGF, PDGF, and fibroblast growth factor (FGF) receptor tyrosine kinases. Compounds in this class, such as 5 (TKI258), are reversible ATP-competitive inhibitors of VEGFR-2, FGFR-1, and PDGFRbeta with IC(50) values <0.1 microM. On the basis of its favorable in vitro and in vivo properties, compound 5 was selected for clinical evaluation and is currently in phase I clinical trials.

Design and structure-activity relationship of heterocyclic analogs of 4-amino-3-benzimidazol-2-ylhydroquinolin-2-ones as inhibitors of receptor tyrosine kinases.

Herein are described a series of novel heterocyclic analogs of the 4-amino-3-benzimidazol-2-ylhydroquinolin-2-one scaffold. These compounds are potent inhibitors of receptor tyrosine kinases and exhibit favorable pharmacokinetic profiles. The synthesis and SAR of these compounds are described.