Greg Gorman

Small Molecules Revealed in a Screen Targeting Epithelial Scattering Are Inhibitors of Microtubule Polymerization.

Stimulation of cultured epithelial cells with scatter factor/hepatocyte growth factor (HGF) results in the detachment of cell-cell junctions and initiation of cell migration. Instead of coordinating collective cell behavior within a tissue, cells become solitary and have few cell-cell interactions. Since epithelial scattering is recapitulated in cancer progression and since HGF signaling drives cancer metastasis in many cases, inhibitors of HGF signaling have been proposed to act as anticancer agents. We previously sought to better understand critical components required for HGF-induced epithelial scattering by performing a forward chemical genetics screen, which resulted in the identification of compounds with no previously reported biological activity that we report here. In efforts to determine the mechanism of these compounds, we find that many compounds have broad antiproliferative effects on cancer cell lines by arrest of cell division in G2/M with minimal induction of apoptosis. This effect is reminiscent of microtubule-targeting agents, and we find that several of these scaffolds directly inhibit microtubule polymerization. Compounds are assessed for their toxicity and pharmacokinetics in vivo. The identification of novel small-molecule inhibitors of microtubule polymerization highlights the role of the microtubule cytoskeleton in HGF-induced epithelial scattering.

Multicenter Phase IB Trial of Carboxyamidotriazole Orotate and Temozolomide for Recurrent and Newly Diagnosed Glioblastoma and Other Anaplastic Gliomas

Purpose Carboxyamidotriazole orotate (CTO) is a novel oral inhibitor of non-voltage-dependent calcium channels with modulatory effects in multiple cell-signaling pathways and synergistic effects with temozolomide (TMZ) in glioblastoma (GBM) models. We conducted a phase IB study combining CTO with two standard TMZ schedules in GBM. Methods In cohort 1, patients with recurrent anaplastic gliomas or GBM received escalating doses of CTO (219 to 812.5 mg/m2 once daily or 600 mg fixed once-daily dose) combined with TMZ (150 mg/m2 5 days during each 28-day cycle). In cohort 2, patients with newly diagnosed GBM received escalating doses of CTO (219 to 481 mg/m2/d once daily) with radiotherapy and TMZ 75 mg/m2/d, followed by TMZ 150 mg to 200 mg/m2 5 days during each 28-day cycle. Results Forty-seven patients were enrolled. Treatment was well tolerated; toxicities included fatigue, constipation, nausea, and hypophosphatemia. Pharmacokinetics showed that CTO did not alter TMZ levels; therapeutic concentrations were achieved in tumor and brain. No dose-limiting toxicities were observed; the recommended phase II dose was 600 mg/d flat dose. Signals of activity in cohort 1 (n = 27) included partial (n = 6) and complete (n = 1) response, including in O6-methylguanine-DNA methyltransferase unmethylated and bevacizumab-refractory tumors. In cohort 2 (n = 15), median progression-free survival was 15 months and median overall survival was not reached (median follow-up, 28 months; 2-year overall survival, 62%). Gene sequencing disclosed a high rate of responses among EGFR-amplified tumors ( P = .005), with mechanisms of acquired resistance possibly involving mutations in mismatch-repair genes and/or downstream components TSC2, NF1, NF2, PTEN, and PIK3CA. Conclusion CTO can be combined safely with TMZ or chemoradiation in GBM and anaplastic gliomas, displaying favorable brain penetration and promising signals of activity in this difficult-to-treat population.

Physical Compatibility of Micafungin With Sodium Bicarbonate Hydration Fluids Commonly Used With High-Dose Methotrexate Chemotherapy:

Purpose: The purpose of this study was to determine the physical compatibility of micafungin with commonly used concentrations of sodium bicarbonate hydration fluids administered via a Y-site connected to a central venous catheter (Y-site/CVC). Methods: Micafungin sodium (evaluated concentration of 1.5 mg/mL) was combined in a 3:1 (vehicle:drug) ratio with the following commonly used hydration vehicles: 40 mEq/L sodium bicarbonate in 5% dextrose in water with ¼ normal saline (40SB-D5W-1/4NS), 75 mEq/L sodium bicarbonate in D5W (75SB-D5W), and 154 mEq/L sodium bicarbonate in D5W (154SB-D5W). A 3:1 ratio was used based on the flow rates (typically 125 mL/m2/h for bicarbonate-containing vehicles and 50 mL/h for micafungin) of the corresponding solutions in a clinical setting. Visual observations recorded to determine physical compatibility included visual inspection against different backgrounds (unaided, black, and white). Other physical observations were as follows: odor, evolution of gas, pH, and turbidity immediately recorded after mixing and at specified time points up to 2 hours. Evaluations at each time point were compared against baseline observation values at Time 0. Results: All combinations tested were found to be compatible up to 2 hours. Time points beyond 2 hours cannot be safely verified as compatible. Conclusion: Micafungin may be administered safely using a Y-site/CVC delivery system with all the vehicles tested in this study.

The Association Between Lithium in Drinking Water and Incidence of Suicide Across 15 Alabama Counties

Background: Recent studies have shown that lithium may be effective at reducing suicide at low doses, such as those found in drinking water. Aims: The purpose of this study was to compare suicide rates with natural lithium levels in the drinking water of various Alabama counties. Method: Five drinking water samples from each of 15 Alabama counties were collected. Lithium levels were measured in triplicate using an inductively coupled plasma emission spectrophotometer and compared with suicide rate data for the period 1999–2013. Age, gender, and poverty were evaluated as potential confounding variables. Results: The average measured lithium concentrations ranged from 0.4 ppb to 32.9 ppb between the counties tested. The plot of suicide rate versus lithium concentration showed a statistically significant inverse relationship (r = −.6286, p = .0141). Evaluation of male-only suicide rate versus lithium concentration data also yielded significant results; however, the female-only rate was not significant. Age standardized suicide rates and poverty when individually compared against lithium levels were also found to be statistically significant; unexpectedly, however, poverty had a parallel trend with suicide rate. Conclusion: Lithium concentration in drinking water is inversely correlated with suicide rate in 15 Alabama counties.

A novel class of mono-alkylating agents with highly potent and selective tumor cell growth inhibitory activity.

e13523 Background: Recent studies have shown that siRNA knockdown of the cGMP-specific phosphodiesterase, PDE5 can suppress growth and induce apoptosis of human breast tumor cells. However, conventional PDE5 inhibitors have only modest in vitro tumor cell growth inhibitory activity at concentrations that cannot be achieved in vivo. We hypothesized that this may be attributed to the reversible nature of their binding to PDE5. METHODS A series of alkyl halide derivatives of the PDE5 inhibitor, tadalafil were synthesized and evaluated for in vitro tumor cell growth inhibitory activity, mechanism of action, tumor selectively, and in vivo antitumor activity. RESULTS Among 18 derivatives synthesized, 15 inhibited the growth of human breast MDA-MB-231 tumor cells with IC50 values in the 10-9 to 10-6 M range. Compound 6 potently inhibited tumor cell growth with an IC50 of 6 nM and induced apoptosis. Normal human mammary epithelial cells that do not express PDE5 were insensitive to treatment, while breast tumor cell lines that express PDE5 were highly sensitive. Compound 6 selectively suppressed cGMP hydrolysis in lysates from treated cells and increased intracellular cGMP levels. Moreover, intermittent treatment (3hrs) suppressed growth as effectively as continuous treatment (72hrs). These observations along with molecular docking studies are consistent with a mechanism involving irreversible PDE5 inhibition. Screening in the NCI-60 panel revealed striking sensitivity among most human tumor cell lines from breast, renal, CNS, ovarian, and hematological origin with IC50 values in the low nanomolar range. Compound 10 was predicted to have favorable pharmacokinetic properties and evaluated for in vivo antitumor efficacy. With an IC50 of 2 nM to inhibit human Caki-1 renal tumor cell growth, compound 10 significantly suppressed tumor growth in the Caki-1 xenograft mouse model. CONCLUSIONS Mono-alkylating derivatives of tadalafil have potential therapeutic utility for a broad range of solid and hematological tumors.

Abstract 1865: Colon cancer chemopreventive properties of a non-cyclooxygenase inhibitory amide derivative of sulindac

Previous studies have concluded that the mechanism responsible for the antineoplastic properties of NSAIDs is cyclooxygenase (COX) independent, which suggests that more selective drugs can be developed for cancer chemoprevention by targeting such mechanisms. With this paradigm, we are synthesizing novel sulindac derivatives that have reduced COX inhibitory activity, but enhanced tumor cell growth inhibitory activity. A prototypic dimethylethyl amide derivative referred to as sulindac sulfide amide (SSA) was previously reported to lack COX-1 or COX-2 inhibitory activity, yet have improved potency to inhibit tumor cell growth in vitro. For example, SSA inhibited the growth of human HT-29 colon tumor cells with IC 50 values of 1-2 µM compared with 70-90 µM for sulindac sulfide (SS), a non-selective COX inhibitor. SSA was also appreciably more effective than SS in inhibiting HT-29 colon tumor cell growth using a 3-dimensional in vitro tumor cell model. SSA induced apoptosis of HT-29 carcinoma cells, but normal human colonocytes were insensitive to treatment, suggesting an element of tumor selectivity. The mechanism of SSA induced apoptosis is associated with cGMP phosphodiesterase (PDE) inhibition, elevation of intracellular cGMP, and activation of protein kinase G, which also appears to be an important off-target effect of SS. SSA inhibited the growth of a variety of histologically diverse tumor cell lines, an effect that is consistent with studies showing the overexpression of PDE5 in various tumor types, including colorectal adenomas and carcinomas. SSA was well tolerated in the FCCC Min mouse model in which oral administration reduced colon tumor multiplicity by approximately 80% and tumor incidence by 50%. SSA also inhibited tumor growth in the human HT-29 colon mouse xenograft model by approximately 60%, while sulindac at its maximum tolerated dose was marginally effective. The antitumor activity of SSA in the HT-29 model was accompanied by decreased numbers of proliferating cells and increased numbers of apoptotic cells as determined by immunohistochemistry. Pharmacokinetic studies in mice bearing HT-29 xenografts revealed that plasma and tumor levels of SSA from a tolerated dose of SSA appreciably exceeded the in vitro IC 50 value for growth inhibition. In contrast, sulindac generated plasma and tumor levels of SS that were appreciably less than the IC 50 value for tumor cell growth inhibition. These results support the feasibility of chemically modifying sulindac to design out COX associated toxicities, while increasing anticancer efficacy. Newer sulindac derivatives with higher potency and target selectivity, as well as formulations to improve oral bioavailability are being developed for colon cancer chemoprevention. Funding provided by NIH/NCI grants CA131378 and CA148817. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1865. doi:10.1158/1538-7445.AM2011-1865