Esophageal cancer dose escalation using a simultaneous integrated boost technique.

PURPOSE: We previously showed that 75% of radiation therapy (RT) failures in patients with unresectable esophageal cancer are in the gross tumor volume (GTV). We performed a planning study to evaluate if a simultaneous integrated boost (SIB) technique could selectively deliver a boost dose of radiation to the GTV in patients with esophageal cancer. METHODS AND MATERIALS: Treatment plans were generated using four different approaches (two-dimensional conformal radiotherapy [2D-CRT] to 50.4 Gy, 2D-CRT to 64.8 Gy, intensity-modulated RT [IMRT] to 50.4 Gy, and SIB-IMRT to 64.8 Gy) and optimized for 10 patients with distal esophageal cancer. All plans were constructed to deliver the target dose in 28 fractions using heterogeneity corrections. Isodose distributions were evaluated for target coverage and normal tissue exposure. RESULTS: The 50.4 Gy IMRT plan was associated with significant reductions in mean cardiac, pulmonary, and hepatic doses relative to the 50.4 Gy 2D-CRT plan. The 64.8 Gy SIB-IMRT plan produced a 28% increase in GTV dose and comparable normal tissue doses as the 50.4 Gy IMRT plan; compared with the 50.4 Gy 2D-CRT plan, the 64.8 Gy SIB-IMRT produced significant dose reductions to all critical structures (heart, lung, liver, and spinal cord). CONCLUSIONS: The use of SIB-IMRT allowed us to selectively increase the dose to the GTV, the area at highest risk of failure, while simultaneously reducing the dose to the normal heart, lung, and liver. Clinical implications warrant systematic evaluation.

Cartilage degradation biomarkers predict efficacy of a novel, highly selective matrix metalloproteinase 13 inhibitor in a dog model of osteoarthritis: confirmation by multivariate analysis that modulation of type II collagen and aggrecan degradation peptides parallels pathologic changes.

OBJECTIVE: To demonstrate that the novel highly selective matrix metalloproteinase 13 (MMP-13) inhibitor PF152 reduces joint lesions in adult dogs with osteoarthritis (OA) and decreases biomarkers of cartilage degradation. METHODS: The potency and selectivity of PF152 were evaluated in vitro using 16 MMPs, TACE, and ADAMTS-4 and ADAMTS-5, as well as ex vivo in human cartilage explants. In vivo effects were evaluated at 3 concentrations in mature beagles with partial medial meniscectomy. Gross and histologic changes in the femorotibial joints were evaluated using various measures of cartilage degeneration. Biomarkers of cartilage turnover were examined in serum, urine, or synovial fluid. Results were analyzed individually and in combination using multivariate analysis. RESULTS: The potent and selective MMP-13 inhibitor PF152 decreased human cartilage degradation ex vivo in a dose-dependent manner. PF152 treatment of dogs with OA reduced cartilage lesions and decreased biomarkers of type II collagen (type II collagen neoepitope) and aggrecan (peptides ending in ARGN or AGEG) degradation. The dose required for significant inhibition varied with the measure used, but multivariate analysis of 6 gross and histologic measures indicated that all doses differed significantly from vehicle but not from each other. Combined analysis of cartilage degradation markers showed similar results. CONCLUSION: This highly selective MMP-13 inhibitor exhibits chondroprotective effects in mature animals. Biomarkers of cartilage degradation, when evaluated in combination, parallel the joint structural changes induced by the MMP-13 inhibitor. These data support the potential therapeutic value of selective MMP-13 inhibitors and the use of a set of appropriate biomarkers to predict efficacy in OA clinical trials.

IGFBP-5 Metabolism Is Disrupted in the Rat Medial Meniscal Tear Model of Osteoarthritis.

Insulin-like growth factor binding protein 5 (IGFBP-5) has been proposed to promote cartilage anabolism through insulin-like growth factor (IGF-1) signaling. A proteolytic activity towards IGFBP-5 has been detected in synovial fluids from human osteoarthritic (OA) joints. The purpose of this study was to determine if protease activity towards IGFBP-5 is present in the rat medial meniscal tear (MMT) model of OA and whether inhibition of this activity would alter disease progression. Sprague-Dawley rats were subject to MMT surgery. Synovial fluid lavages were assessed for the presence of IGFBP-5 proteolytic activity. Treatment animals received intra-articular injections of vehicle or protease inhibitor peptide PB-145. Cartilage lesions were monitored by India ink staining followed by macroscopic measurement of lesion width and depth. The MMT surgery induced a proteolytic activity towards IGFPB-5 that was detectable in joint fluid. This activity was stimulated by calcium and was sensitive to serine protease inhibitors as well as peptide PB-145. Significantly, intra-articular administration of PB-145 after surgery protected cartilage from lesion development. PB-145 treatment also resulted in an increase in cartilage turnover as evidenced by increases in serum levels of procollagen type II C-propeptide (CPII) as well as synovial fluid lavage levels of collagen type II neoepitope (TIINE). IGFBP-5 metabolism is disrupted in the rat MMT model of OA, potentially contributing to cartilage degradation. Inhibition of IGFBP-5 proteolysis protected cartilage from lesion development and enhanced cartilage turnover. These data are consistent with IGFBP-5 playing a positive role in anabolic IGF signaling in cartilage.

Discovery of (pyridin-4-yl)-2H-tetrazole as a novel scaffold to identify highly selective matrix metalloproteinase-13 inhibitors for the treatment of osteoarthritis.

Potent, highly selective and orally-bioavailable MMP-13 inhibitors have been identified based upon a (pyridin-4-yl)-2H-tetrazole scaffold. Co-crystal structure analysis revealed that the inhibitors bind at the S(1)(') active site pocket and are not ligands for the catalytic zinc atom. Compound 29b demonstrated reduction of cartilage degradation biomarker (TIINE) levels associated with cartilage protection in a preclinical rat osteoarthritis model.

CJ-13610, an orally active inhibitor of 5-lipoxygenase is efficacious in preclinical models of pain.

Zileuton, a redox and iron chelator 5-lipoxygenase (5-LOX) inhibitor and, leukotriene receptor antagonists are presently used clinically in the long term treatment of asthma. Recent data implicate 5-LOX pathway in pain signaling. We report 5-LOX expression in the central nervous system (CNS) and analyze the pain efficacy of a new class of non redox, non iron chelating 5-LOX inhibitor. CJ-13610, 4-(3-(4-(2-methyl-1H-imidazol-1-yl) phenylthio) phenyl)-tetrahydro-2H-pyran-4-carboxamide, demonstrated antihyperalgesic activity in inflammatory pain models including the acute carrageenan model and the chronic inflammatory model using complete Freund's adjuvant. Following complete Freund's adjuvant stimulus leukotrieneB(4) concentration in the brain was elevated (9+/-1 ng/g, mean+/-S.E.M.) by about 3 times that of the control group (3+/-0.11, mean+/-S.E.M.). Hyperalgesia and leukotrieneB(4) concentration were both reversed following CJ-13610 treatment. Furthermore, we demonstrate CJ-13610 efficacy against osteoarthritis like pain using the rat medial meniscal transection model. CJ-13610 at oral doses of 0.6, 2 and 6 mg/kg/day reversed two modalities of pain in this model; tactile allodynia and weight bearing differential. Taken together, these data suggest that 5-LOX pathway and the leukotriene products are important mediators of pain.

Synthesis of pyrazoles and isoxazoles as potent alpha(v)beta3 receptor antagonists.

We describe a series of pyrazole and isoxazole analogs as antagonists of the alpha(v)beta3 receptor. Compounds showed low to sub-nanomolar potency against alpha(v)beta3, as well as good selectivity against alpha(IIb)beta3. In HT29 cells, most analogs also demonstrated significant selectivity against alpha(v)beta6. Several compounds showed good pharmacokinetic properties in rats, in addition to anti-angiogenic activity in a mouse corneal micropocket model. Compounds were synthesized in a straightforward manner from readily available glutarate precursors.

Anti-metastatic properties of RGD-peptidomimetic agents S137 and S247.

Integrins expressed on endothelial cells modulate cell migration and survival during angiogenesis. Integrins expressed on carcinoma cells potentiate metastasis by facilitating invasion and movement across blood vessels. We describe the activities of two synthetic low-molecular-weight peptidomimetics of the ligand amino acid sequence arg-gly-asp (RGD) in integrin-based functional assays in vitro. We also evaluate efficacy and potential mechanisms of action in models of both spontaneous and experimental metastasis. Broad-spectrum potency against the family of alpha v subunit-containing integrins was observed, with significantly less potency against alpha5beta1 and alpha(IIb)beta3. Both endothelial and tumor cell migration mediated by alpha(v)beta3 was inhibited, whereas proliferation of endothelial cells but not tumor cells was diminished. Continuous infusion of compound by minipumps or oral administration twice daily significantly reduced metastatic tumor burden in the lungs of mice despite no reduction in growth of 435/HAL primary tumors, and only a slight reduction in tumor cells detected in circulating blood. Delaying treatment in this model until after extensive dissemination of tumor cells to the lungs had occurred, and after primary tumor resection, still produced significant efficacy. Conversely, administration of the agent for only the first 18 h after tumor-cell inoculation into the tail vein also resulted in decreased metastases observed after several weeks. These data suggest these compounds or their relatives have potential to interfere with both early and late steps of metastasis involving tumor and endothelial cell functions. Furthermore, the metastatic process can be effectively inhibited independently of primary tumor growth using integrin antagonists.