Targeting the Somatostatin Receptor 2 with the Miniaturized Drug Conjugate, PEN-221: A Potent and Novel Therapeutic for the Treatment of Small Cell Lung Cancer.

Small cell lung cancer (SCLC) is an aggressive neuroendocrine carcinoma with a 95% mortality rate with no improvement to treatment in decades, and new therapies are desperately needed. PEN-221 is a miniaturized peptide-drug conjugate (∼2 kDa) designed to target SCLC via a Somatostatin Receptor 2 (SSTR2)-targeting ligand and to overcome the high proliferation rate characteristic of this disease by using the potent cytotoxic payload, DM1. SSTR2 is an ideal target for a drug conjugate, as it is overexpressed in SCLC with limited normal tissue expression. In vitro, PEN-221 treatment of SSTR2-positive cells resulted in PEN-221 internalization and receptor-dependent inhibition of cellular proliferation. In vivo, PEN-221 exhibited rapid accumulation in SSTR2-positive SCLC xenograft tumors with quick clearance from plasma. Tumor accumulation was sustained, resulting in durable pharmacodynamic changes throughout the tumor, as evidenced by increases in the mitotic marker of G2-M arrest, phosphohistone H3, and increases in the apoptotic marker, cleaved caspase-3. PEN-221 treatment resulted in significant antitumor activity, including complete regressions in SSTR2-positive SCLC xenograft mouse models. Treatment was effective using a variety of dosing schedules and at doses below the MTD, suggesting flexibility of dosing schedule and potential for a large therapeutic window in the clinic. The unique attributes of the miniaturized drug conjugate allowed for deep tumor penetration and limited plasma exposure that may enable long-term dosing, resulting in durable tumor control. Collectively, these data suggest potential for antitumor activity of PEN-221 in patients with SSTR2-positive SCLC.

Ranking nano-enabled hybrid media for simultaneous removal of contaminants with different chemistries: Pseudo-equilibrium sorption tests versus column tests.

The underlying hypothesis of this study was that pseudo-equilibrium and column testing conditions would provide the same sorbent ranking trends although the values of sorbents' performance descriptors (e.g. sorption capacity) may vary because of different kinetics and competition effects induced by the two testing approaches. To address this hypothesis, nano-enabled hybrid media were fabricated and its removal performances were assessed for two model contaminants under multi-point batch pseudo-equilibrium and continuous-flow conditions. Calculation of simultaneous removal capacity indices (SRC) demonstrated that the more resource demanding continuous-flow tests are able to generate the same performance rankings as the ones obtained by conducing the simpler pseudo-equilibrium tests. Furthermore, continuous overlap between the 98% confidence boundaries for each SRC index trend, not only validated the hypothesis that both testing conditions provide the same ranking trends, but also pointed that SRC indices are statistically the same for each media, regardless of employed method. In scenarios where rapid screening of new media is required to obtain the best performing synthesis formulation, use of pseudo-equilibrium tests proved to be reliable. Considering that kinetics induced effects on sorption capacity must not be neglected, more resource demanding column test could be conducted only with the top performing media that exhibit the highest sorption capacity.

Growth differentiating factor-15 (GDF-15): A potential biomarker and therapeutic target for cancer-associated weight loss.

Growth differentiating factor-15 (GDF-15), also known as macrophage inhibiting factor-1, is a member of the transforming growth factor-ß superfamily, which has been implicated in cancer-associated weight loss. The present study investigated the association between cancer-associated weight loss and plasma GDF-15 concentration, as well as other biomarkers, in patients with metastatic lung or exocrine pancreatic cancer. A total of 218 patients were enrolled over a 1-year period. The patient cohort included 152 patients with incurable lung cancer and 66 patients with incurable pancreatic cancer. Of the 218 patients, 98 (45%) reported >5% weight loss, 62 (28%) reported ≤5% weight loss and 58 (27%) reported no weight loss in the 6 months prior to diagnosis. In lung cancer patients, higher circulating GDF-15 levels were significantly associated with weight loss; lung cancer patients who reported >5% weight loss (n=56) were found to exhibit twice the circulating concentration of GDF-15 compared with those that exhibited no weight loss (n=48) (P<0.0001). Additional mediators, including Activin A, interleukin (IL)-12, vascular endothelial growth factor A, IL-1 receptor α, eotaxin and platelet derived growth factor-BB, were also associated with weight loss; however, the associations were not as strong. In pancreatic cancer patients, no association between GDF-15 levels and weight loss was identified. However, higher circulating GDF-15 levels were consistently associated with poor survival in univariate [hazard ratio (HR), 1.13; 95% confidence interval (CI), 1.02-1.23; P=0.016] and multivariate [HR, 1.1; 95% CI, 1.02-1.24; P=0.03] analysis, respectively. Thus, GDF-15 requires further study as a biomarker and potential therapeutic target in cancer-associated weight loss, particularly in lung cancer patients.

A pharmacodynamic/pharmacokinetic study of ficlatuzumab in patients with advanced solid tumors and liver metastases.

PURPOSE: This study evaluated the safety, tolerability, pharmacodynamics, pharmacokinetics, and antitumor activity of ficlatuzumab, a humanized hepatocyte growth factor (HGF) inhibitory monoclonal antibody, as monotherapy in patients with advanced solid tumors and liver metastases. PATIENTS AND METHODS: Patients with p-Met (phosphorylated c-Met)-positive tumors enrolled in three dose-escalation cohorts, receiving ficlatuzumab 2, 10, or 20 mg/kg once per 14-day cycle. Pharmacodynamic changes in liver tumor biopsies and serum, pharmacokinetics, safety, and clinical activity were assessed. RESULTS: No dose-limiting toxicities occurred in the 19 patients enrolled (n = 6, 2 mg/kg; n = 7, 10 mg/kg; n = 6, 20 mg/kg). The most frequent diagnosis was colorectal cancer (n = 15; 79%). The most common treatment-emergent adverse events were asthenia, peripheral edema, hepatic pain (32% each), and cough (26%). Laboratory abnormalities of decreased serum albumin were present in all patients. Ficlatuzumab at 20 mg/kg lowered median levels of tumor p-Met (-53%), p-ERK (-43%), p-Akt (-2%), and increased median HGF levels (+33%), at the last on-study time point relative to baseline. Mean serum HGF levels increased with ficlatuzumab dose and number of treatment cycles. Ficlatuzumab exhibited linear pharmacokinetics and long terminal half-life (7.4-10 days). Best overall response was stable disease in 28% of patients, including 1 patient with pancreatic cancer with stable disease >1 year. CONCLUSIONS: Ficlatuzumab exhibited good safety/tolerability and demonstrated ability to modulate the HGF/c-Met pathway and downstream signaling in the tumor in patients with advanced solid tumors. Safety, pharmacodynamic, and pharmacokinetic data for ficlatuzumab confirmed the recommended phase II dose of 20 mg/kg once per 14-day cycle.

Neural network-based QSAR and insecticide discovery: spinetoram.

Improvements in the efficacy and spectrum of the spinosyns, novel fermentation derived insecticide, has long been a goal within Dow AgroSciences. As large and complex fermentation products identifying specific modifications to the spinosyns likely to result in improved activity was a difficult process, since most modifications decreased the activity. A variety of approaches were investigated to identify new synthetic directions for the spinosyn chemistry including several explorations of the quantitative structure activity relationships (QSAR) of spinosyns, which initially were unsuccessful. However, application of artificial neural networks (ANN) to the spinosyn QSAR problem identified new directions for improved activity in the chemistry, which subsequent synthesis and testing confirmed. The ANN-based analogs coupled with other information on substitution effects resulting from spinosyn structure activity relationships lead to the discovery of spinetoram (XDE-175). Launched in late 2007, spinetoram provides both improved efficacy and an expanded spectrum while maintaining the exceptional environmental and toxicological profile already established for the spinosyn chemistry.

Structure-activity relationship development of dihaloaryl triazole compounds as insecticides and acaricides. 1. Phenyl thiophen-2-yl triazoles.

An extended lipophilic system that incorporated some key elements of first-generation 2,6-dihaloaryl actives, such as 1, demonstrated desirable efficacy against chewing insects as well as sap-feeding insects. These four-ring systems, based on 2, were accessed primarily via Suzuki couplings of halothiophene derivatives with appropriately substituted boronic acids. In particular, phenylthiophene systems that incorporated haloxyether groups, such as those in 3, 4, and 5, had the broadest spectrum of activity across chewing and sap-feeding insect pests. Expansion of this structure-activity relationship to include compounds with differing substitution patterns on the thiophene-C-ring and aryl-D-rings was undertaken. The synthesis and insecticidal activity of 3-aryl-5-(thiophen-2-yl)-1-methyl-1H-[1,2,4]triazoles will be described.

Engineering of the spinosyn PKS: directing starter unit incorporation.

The spinosyns are a family of potent and highly selective insect control agents that display a favorable environmental profile. As some regions of the spinosyn molecule are recalcitrant to chemical modification, a targeted genetic approach was carried out to generate new analogues. The polyketide synthase (PKS) loading modules from the avermectin PKS of Streptomyces avermitilis and the erythromcyin PKS of Saccharopolyspora erythraea were each used to replace the spinosyn PKS loading module. Both of the resulting strains containing hybrid PKS pathways produced the anticipated spinosyn analogues. Supplementation of the culture media with a range of exogenous carboxylic acids led to the successful incorporation of these novel elements to yield further novel spinosyn molecules, some of which demonstrated potent and new insecticidal activities. Furthermore, it has been demonstrated that semisynthesis of such novel metabolites can then be used to generate active analogues, demonstrating the effectiveness of utilizing these complementary methods to search the chemical space around this template.

Dihydropiperazine neonicotinoid compounds. Synthesis and insecticidal activity.

Syntheses of various isomeric dihydropiperazines can be approached successfully by taking advantage of the regioselective monothionation of their respective diones. Preparation of the precursor unsymmetrical N-substituted piperazinediones from readily available diamines is key to this selectivity. The dihydropiperazine ring system, as exemplified in 1-[(6-chloropyridin-3-yl)methyl]-4-methyl-3-oxopiperazin-2-ylidenecyanamide (4) and 1-[(2-chloro-1,3-thiazol-5-yl)methyl]-4-methyl-3-oxopiperazin-2-ylidenecyanamide (25), has been shown to be a suitable bioisosteric replacement for the imidazolidine ring system contained in neonicotinoid compounds. However, placement of the cyanoimino electron-withdrawing group further removed from the pyridine ring, as in 4-[(6-chloropyridin-3-yl)methyl]-3-oxopiperazin-2-ylidenecyanamide (3a), or relocation of the carbonyl group, as in 1-[(6-chloropyridin-3-yl)methyl]-4-methyl-5-oxopiperazin-2-ylidenecyanamide (5), results in significantly decreased bioisosterism. The dihydropiperazine ring system of 4 and 25 also lends a degree of rigidity to the molecule that is not offered by the inactive acyclic counterpart 2-[(6-chloropyridin-3-yl)-methyl-(methyl)amino]-2-(cyanoimino)-N,N-dimethylacetamide (6). A pharmacophore model is proposed that qualitatively explains the results on the basis of good overlap of the key pharmacophore elements of 4 and imidacloprid (1); the less active regioisomers of 4 (3a, 5, and 6) feature a smaller degree of overlap.