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For the purpose of seeking new antibiotics, researchers usually modify the already-existing ones. However, this strategy has been extensively used and is close to its limits, especially in the case of aminoglycosides, and it is difficult to find a proper aminoglycoside antibiotic for novel modification. In this paper, we reported the design, synthesis, and evaluation of a series of 5-epi-neamine derivatives based on the structural information of bacterial 16S RNA A-site binding with aminoglycosides. Bioassay results showed that our design strategy was feasible. Our study offers a new way to search for structurally novel aminoglycosides. Meanwhile, our study provides valuable structure-activity relationship information, which will lead to better understanding and exploitation of the drug target, and improved development of new aminoglycoside antibiotics.

OSU-2S is a FTY720 (Fingolimod) derivative that lacks immunosuppressive properties but exhibits strong anti-tumour activity in several haematological and solid tumour models. We have recently shown OSU-2S to mediate potent cytotoxicity in human mantle cell lymphoma cell lines and primary cells. We report here the pre-clinical activity of OSU-2S in spontaneous B-cell lymphoma of dogs which shares many characteristics of human lymphoma. OSU-2S mediated apoptosis in canine B-cell lines and primary B-cell lymphoma cells obtained from spontaneous lymphoma bearing dogs. OSU-2S induced reactive oxygen species (ROS) in canine lymphoma cells and inhibition of ROS partially rescued OSU-2S-mediated cell death. These studies provide a rational basis for the use of spontaneous lymphoma in pet dogs as a preclinical large animal model for the development of OSU-2S as small molecule for treating people and dogs with lymphoma.

On the basis of our finding that the antitumor effect of 5-{4-[(1-methylcyclohexyl)methoxy]benzyl}thiazolidine-2,4-dione, a thiazolidinedione peroxisome proliferator-activated receptor (PPAR)γ agonist, was, in part, attributable to its ability to block glucose uptake independently of PPARγ, we used its PPARγ-inactive analogue to develop a novel class of glucose transporter (GLUT) inhibitors. This lead optimization led to compound 30 {5-(4-hydroxy-3-trifluoromethylbenzylidene)-3-[4,4,4-trifluoro-2-methyl-2-(2,2,2-trifluoroethyl)butyl]thiazolidine-2,4-dione} as the optimal agent, which exhibited high antitumor potency through the suppression of glucose uptake (IC(50), 2.5 μM), while not cytotoxic to prostate and mammary epithelial cells. This glucose uptake inhibition was associated with the inhibition of GLUT1 (IC(50), 2 μM). Moreover, the mechanism of antitumor action of compound 30 was validated by its effect on a series of energy restriction-associated cellular responses. Homology modeling analysis suggests that the inhibitory effect of compound 30 on glucose entry was attributable to its ability to bind to the GLUT1 channel at a site distinct from that of glucose.

OSU-2S is a novel anti-cancer and immune modulatory agent designed specifically to avert the immunosuppressive effects and related toxicities observed in clinical studies with its predecessor analog, FTY720. To characterize its preclinical pharmacokinetics, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantification of OSU-2S in mouse plasma. Ethyl acetate extraction of samples containing OSU-2S and the internal standard, Sph-17, was followed by separation with a 6 minute gradient (water/0.1% formic acid and methanol/0.1% formic acid) on a reverse-phase C18 column at room temperature. Selected reaction monitoring was used for detection on a triple quadrupole mass spectrometer with positive ionization. The assay was linear over the concentration range 3–3000 ng/mL with accuracy ranging from 103 to 111%, and both within- and between-run precision (CV%) ≤11%. All stability samples were within ±15% of nominal values, and replicates were within 15% CV. The assay was successfully applied to a mouse pharmacokinetic study of OSU-2S with intravenous and intraperitoneal administration. OSU-2S non-compartmental pharmacokinetic parameters, area under the concentration-time curve, clearance, and elimination half-life were estimated at 1522 hr*μg/L, 3.06 L/hr/kg and 15.6 hr, respectively, for intravenous injection. Systemic availability after intraperitoneal injection was approximately 46%. These data demonstrate the OSU-2S compound displays acceptable pharmacokinetic properties for further in vivo pharmacologic evaluation, which can be facilitated by the validated LC-MS/MS assay.

Selective cytotoxicity to cancer cells without compromising their normal counterparts pose a huge challenge for traditional drug design. Here we developed a tumor antigen-targeted delivery of immunonanoparticle carrying a novel non-immunosuppressive FTY720 derivative OSU-2S with potent cytotoxicity against leukemic B cells. OSU-2S induces activation of protein phosphatase 2A (PP2A), phosphorylation and nuclear translocation of SHP1(S591) and deregulation of multiple cellular processes in chronic lymphocytic leukemia (CLL) resulting in potent cytotoxicity. To preclude OSU-2S-mediated effects on these ubiquitous phosphatases in unintended cells and avoid potential adverse effects, we developed an OSU-2S-targeted delivery of immunonanoparticles (2A2-OSU-2S-ILP), that mediated selective cytotoxicity of CLL but not normal B cells through targeting receptor tyrosine kinase ROR1 expressed in leukemic but not normal B cells. Developing a novel spontaneous CLL mouse model expressing human ROR1 (hROR1) in all leukemic B cells, we demonstrate the therapeutic benefit of enhanced survival with 2A2-OSU-2S-ILP in vivo. The newly developed non-immunosuppressive OSU-2S, its delivery using human CLL directed immunonanoparticles and the novel transgenic (Tg) mouse model of CLL that expresses hROR1 exclusively in leukemic B cell surface are highly innovative and can be applied to CLL and other ROR1+ malignancies including mantle cell lymphoma and acute lymphoblastic leukemia.

Gemcitabine resistance remains a significant clinical challenge. Here, we used a novel glucose transporter (Glut) inhibitor, CG-5, as a proof-of-concept compound to investigate the therapeutic utility of targeting the Warburg effect to overcome gemcitabine resistance in pancreatic cancer. The effects of gemcitabine and/or CG-5 on viability, survival, glucose uptake and DNA damage were evaluated in gemcitabine-sensitive and gemcitabine-resistant pancreatic cancer cell lines. Mechanistic studies were conducted to determine the molecular basis of gemcitabine resistance and the mechanism of CG-5-induced sensitization to gemcitabine. The effects of CG-5 on gemcitabine sensitivity were investigated in a xenograft tumor model of gemcitabine-resistant pancreatic cancer. In contrast to gemcitabine-sensitive pancreatic cancer cells, the resistant Panc-1 and Panc-1(GemR) cells responded to gemcitabine by increasing the expression of ribonucleotide reductase M2 catalytic subunit (RRM2) through E2F1-mediated transcriptional activation. Acting as a pan-Glut inhibitor, CG-5 abrogated this gemcitabine-induced upregulation of RRM2 through decreased E2F1 expression, thereby enhancing gemcitabine-induced DNA damage and inhibition of cell survival. This CG-5-induced inhibition of E2F1 expression was mediated by the induction of a previously unreported E2F1-targeted microRNA, miR-520f. The addition of oral CG-5 to gemcitabine therapy caused greater suppression of Panc-1(GemR) xenograft tumor growth in vivo than either drug alone. Glut inhibition may be an effective strategy to enhance gemcitabine activity for the treatment of pancreatic cancer.

Mantle-cell lymphoma (MCL) remains incurable despite numerous therapeutic advances. OSU-2S, a novel nonimmunosuppressive FTY720 (Fingolimod) derivative, exhibits potent cytotoxicity in MCL cell lines and primary cells. OSU-2S increased the surface expression of CD74, a therapeutic antibody target in MCL cells. OSU-2S, in combination with anti-CD74 antibody milatuzumab, enhanced cytotoxicity in MCL. Moreover, MCL tumor antigen receptor tyrosine kinase-like orphan receptor 1 (ROR1) targeted immunonanoparticle-carrying OSU-2S (2A2-OSU-2S-ILP)-mediated selective cytotoxicity of MCL in vitro, as well as activity in a xenografted mouse model of MCL in vivo. The newly developed OSU-2S delivery using ROR1-directed immunonanoparticles provide selective targeting of OSU-2S to MCL and other ROR1(+) malignancies, sparing normal B cells.

Previously, we reported that Akt inactivation by γ-tocopherol (2) in PTEN-negative prostate cancer cells resulted from its unique ability to facilitate membrane co-localization of Akt and PHLPP1 (PH domain leucine-rich repeat protein phosphatase isoform 1), a Ser473-specific Akt phosphatase, through pleckstrin homology (PH) domain binding. This finding provided a basis for exploiting 2 to develop a novel class of PHLPP1-targeted Akt inhibitors. Here, we used 3 (γ-VE5), a side chain-truncated 2 derivative, as a scaffold for lead optimization. The proof-of-concept of this structural optimization was obtained by 20, which exhibited higher antitumor efficacy than 3 in PTEN-negative cancer cells through PHLPP1-facilitated Akt inactivation. Like 3, 20 preferentially recognized the PH domains of Akt and PHLPP1, as its binding affinities for other PH domains, including those of ILK and PDK1, were an order-of-magnitude lower. Moreover, 20 was orally active in suppressing xenograft tumor growth in nude mice, which underlines the translational potential of this new class of Akt inhibitor in PTEN-deficient cancers.

On the basis of our finding that the antitumor effect of 5-{4-[(1-methylcyclohexyl)methoxy]benzyl}thiazolidine-2,4-dione, a thiazolidinedione peroxisome proliferator-activated receptor (PPAR)γ agonist, was, in part, attributable to its ability to block glucose uptake independently of PPARγ, we used its PPARγ-inactive analogue to develop a novel class of glucose transporter (GLUT) inhibitors. This lead optimization led to compound 30 {5-(4-hydroxy-3-trifluoromethylbenzylidene)-3-[4,4,4-trifluoro-2-methyl-2-(2,2,2-trifluoroethyl)butyl]thiazolidine-2,4-dione} as the optimal agent, which exhibited high antitumor potency through the suppression of glucose uptake (IC(50), 2.5 μM), while not cytotoxic to prostate and mammary epithelial cells. This glucose uptake inhibition was associated with the inhibition of GLUT1 (IC(50), 2 μM). Moreover, the mechanism of antitumor action of compound 30 was validated by its effect on a series of energy restriction-associated cellular responses. Homology modeling analysis suggests that the inhibitory effect of compound 30 on glucose entry was attributable to its ability to bind to the GLUT1 channel at a site distinct from that of glucose.

Treatment of mantle cell lymphoma (MCL), an uncommon non-Hodgkin's lymphoma, remains challenging despite numerous therapeutic advances. We have previously shown the preclinical effect of FTY720 (Fingolimod) against MCL through down modulation of cyclin D1, the protein almost uniformly over-expressed in this disease. Herein, we describe the potent direct cytotoxicity of OSU-2S, a novel non-immunosuppressive FTY720 derivative in MCL cells and evaluate tumor directed lipid based nanoparticle formulation of OSU-2S designed to selectively deliver to ROR1+ MCL cells. OSU-2S is a FTY720 derivative that does not traffic T cells and exhibits potent cytotoxicity in MCL cell lines and in MCL patient-derived primary cells (p = 0.0049). Exploratory studies aimed to identify the best combination therapies identified induction of cell surface CD74 in primary MCL cells treated with OSU-2S. Similarly, induction of cell surface CD74 was also confirmed in JeKo and Mino cells. Evaluation of OSU-2S and anti-CD74 antibody, milatuzumab in cell lines and primary MCL cells revealed enhanced cytotoxicity compared to either of the agents alone. B-cell malignancy restricted expression of receptor tyrosine kinase ROR1 in MCL, chronic lymphocytic leukemia (CLL) and subset of pediatric acute lymphocytic leukemia (ALL) has been reported. Consistent with this, JeKo, Mino and primary MCL cells but not normal B cells expressed ROR1. As tumor directed delivery of cytotoxic cargo offers the potential to further enhance the therapeutic index of cancer therapeutics such as OSU-2S, we developed a lipid-based OSU-2S nanoparticle (OSU-2S-LP) tethered with an anti-ROR1 mouse monoclonal antibody (2A2) to form 2A2-OSU-2S-ILP that mediated selective cytotoxicity of MCL. Testing of immunonanoparticle formulation on JeKo, Mino cell lines and primary lymphoma cells showed selective cytotoxicity of 2A2-OSU-2S-ILP in MCL (p Citation Format: Rajeswaran Mani, Chi-Ling Chiang, Frank W. Frissora, Ribai Yan, Xiaokui Mo, Sivasubramanian Baskar, Christoph Rader, Mitch Phelps, Ching-Shih Chen, Robert Lee, John Byrd, Robert Baiocchi, L James Lee, Natarajan Muthusamy. ROR1 targeted delivery of OSU-2S, a non-immunosuppressive FTY720 derivative, exerts potent cytotoxicity in mantle cell lymphoma in-vitro and in-vivo. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4406. doi:10.1158/1538-7445.AM2015-4406

The discovery of predominantly inactive phosphatases in a variety of cancers and the potential for phosphatase targeted therapy as an alternative to kinase inhibitors especially in situations where the efficacy of the kinase inhibitors are compromised due to resistance mechanisms attributed to mutations and single nucleotide polymorphisms of the drug targets prompted us to evaluate potential activators of phosphatases in chronic lymphocytic leukemia (CLL) and other B cell malignancies. We have recently identified cytotoxic activity of OSU-2S, a novel non-immunosuppressive FTY720 derivative and PP2A activator against CLL. OSU-2S induced cytotoxicity was associated with PKC dependent phosphorylation of Serine 591 (S591) of tumor suppressor phosphatase SHP1 and its nuclear translocation consistent with a potential role for S591 phosphorylation. Here in, we demonstrate the molecular mechanisms and a rational approach for developing this novel agent for preclinical and clinical studies. In-vitro kinase assay demonstrated OSU-2S increased activity of purified PKC directly (p Disclosures: No relevant conflicts of interest to declare.