Isolation and characterization of two canine melanoma cell lines: new models for comparative oncology.

BACKGROUND: Metastatic melanoma is one of the most aggressive forms of cancer in humans. Among its types, mucosal melanomas represent one of the most highly metastatic and aggressive forms, with a very poor prognosis. Because they are rare in Caucasian individuals, unlike cutaneous melanomas, there has been fewer epidemiological, clinical and genetic evaluation of mucosal melanomas. Moreover, the lack of predictive models fully reproducing the pathogenesis and molecular alterations of mucosal melanoma makes its treatment challenging. Interestingly, dogs are frequently affected by melanomas of the oral cavity that are characterized, as their human counterparts, by focal infiltration, recurrence, and metastasis to regional lymph nodes, lungs and other organs. In dogs, some particular breeds are at high risk, suggesting a specific genetic background and strong genetic drivers. Altogether, the striking homologies in clinical presentation, histopathological features, and overall biology between human and canine mucosal melanomas make dogs invaluable natural models with which to investigate tumor development, including tumor ætiology, and develop tailored treatments. METHODS: We developed and characterized two canine oral melanoma cell lines from tumors isolated from dog patients with distinct clinical profiles; with and without lung metastases. The cells were characterized using immunohistochemistry, pharmacology and genetic studies. RESULTS: We have developed and immunohistochemically, genetically, and pharmacologically characterized. Two cell lines (Ocr_OCMM1X & Ocr_OCMM2X) were produced through mouse xenografts originating from two clinically contrasting melanomas of the oral cavity. Their exhaustive characterization showed two distinct biological and genetic profiles that are potentially linked to the stage of malignancy at the time of diagnosis and sample collection of each melanoma case. These cell lines thus constitute relevant tools with which to perform genetic and drug screening analyses for a better understanding of mucosal melanomas in dogs and humans. CONCLUSIONS: The aim of this study was to establish and characterize xenograft-derived canine melanoma cell lines with different morphologies, genetic features and pharmacological sensitivities that constitute good predictive models for comparative oncology. These cell lines are relevant tools to advance the use of canine mucosal melanomas as natural models for the benefit of both veterinary and human medicine.

Phase I dose escalation study of 12b80 (hydroxybisphosphonate linked doxorubicin) in naturally occurring osteosarcoma.

PURPOSE: 12b80 combines doxorubicin bound to a bone targeting hydroxybisphosphonate vector using a pH-sensitive linker, designed to specifically trigger doxorubicin release in an acidic bone tumor microenvironment. This phase I study aimed to determine the safety and toxicity profiles of 12b80 in dogs with naturally occurring osteosarcoma, with the objective to translate findings from dogs to humans. EXPERIMENTAL DESIGN: Ten client-owned dogs with osteosarcoma were enrolled in an accelerated dose-titration design followed by 3 + 3 design. Dogs received three cycles of 12b80 intravenous injection at 4 mg/kg (n = 1), 6 mg/kg (n = 2), 8 mg/kg (n = 3), and 10 mg/kg (n = 4). Endpoints included safety, tolerability, maximum tolerated dose (MTD), and dose-limiting toxicity (DLT). RESULTS: The MTD of 12b80 was 8 mg/kg (i.e., equivalent dose of doxorubicin of 110 mg/m2, range: 93-126). Most adverse events included grade ≤ 2 gastrointestinal disorders and hypersensitivity reactions. No hematological or cardiac DLT were observed at any dose tested. CONCLUSIONS: In dogs, 12b80 is overall well tolerated and expends the MTD of doxorubicin up to four times the standard dose of 30 mg/m2. These results demonstrate the potential therapeutic benefit of 12b80 in canine and human osteosarcoma.

Randomized, double-blind trial of F14512, a polyamine-vectorized anticancer drug, compared with etoposide phosphate, in dogs with naturally occurring lymphoma.

Purpose: F14512 is an epipodophyllotoxin derivative from etoposide, combined with a spermine moiety introduced as a cell delivery vector. The objective of this study was to compare the safety and antitumor activity of F14512 and etoposide phosphate in dogs with spontaneous non-Hodgkin lymphoma (NHL) and to investigate the potential benefit of F14512 in P-glycoprotein (Pgp) overexpressing lymphomas. Experimental Design: Forty-eight client-owned dogs with intermediate to high-grade NHL were enrolled into a randomized, double-blind trial of F14512 versus etoposide phosphate. Endpoints included safety and therapeutic efficacy. Results: Twenty-five dogs were randomized to receive F14512 and 23 dogs to receive etoposide phosphate. All adverse events (AEs) were reversible, and no treatment-related death was reported. Hematologic AEs were more severe with F14512 and gastrointestinal AEs were more frequent with etoposide phosphate. F14512 exhibited similar response rate and progression-free survival (PFS) as etoposide phosphate in the global treated population. Subgroup analysis of dogs with Pgp-overexpressing NHL showed a significant improvement in PFS in dogs treated with F14512 compared with etoposide phosphate. Conclusion: F14512 showed strong therapeutic efficacy against spontaneous NHL and exhibited a clinical benefice in Pgp-overexpressing lymphoma superior to etoposide phosphate. The results clearly justify the evaluation of F14512 in human clinical trials.

Dose escalation study to evaluate safety, tolerability and efficacy of intravenous etoposide phosphate administration in 27 dogs with multicentric lymphoma.

Comparative oncology has shown that naturally occurring canine cancers are of valuable and translatable interest for the understanding of human cancer biology and the characterization of new therapies. This work was part of a comparative oncology project assessing a new, clinical-stage topoisomerase II inhibitor and comparing it with etoposide in dogs with spontaneous lymphoma with the objective to translate findings from dogs to humans. Etoposide is a topoisomerase II inhibitor widely used in various humans' solid and hematopoietic cancer, but little data is available concerning its potential antitumor efficacy in dogs. Etoposide phosphate is a water-soluble prodrug of etoposide which is expected to be better tolerated in dogs. The objectives of this study were to assess the safety, the tolerability and the efficacy of intravenous etoposide phosphate in dogs with multicentric lymphoma. Seven dose levels were evaluated in a traditional 3+3 phase I design. Twenty-seven owned-dogs with high-grade multicentric lymphoma were enrolled and treated with three cycles of etoposide phosphate IV injections every 2 weeks. Adverse effects were graded according to the Veterinary Cooperative Oncology Group criteria. A complete end-staging was realized 45 days after inclusion. The maximal tolerated dose was 300 mg/m2. At this dose level, the overall response rate was 83.3% (n = 6, 3 PR and 2 CR). Only a moderate reversible gastrointestinal toxicity, no severe myelotoxicity and no hypersensitivity reaction were reported at this dose level. Beyond the characterization of etoposide clinical efficacy in dogs, this study underlined the clinical and therapeutic homologies between dog and human lymphomas.

Baclofen-loaded microspheres in gel suspensions for intrathecal drug delivery: in vitro and in vivo evaluation.

Severe spasticity is a very disabling disorder treated by continuous baclofen intrathecal infusion which unfortunately remains an expensive and uncomfortable treatment. In order to address these issues, new sustained release formulations designed for intrathecal baclofen delivery were sought with the aim of minimising the burst effect of baclofen which can lead to toxicity. Baclofen was encapsulated in poly(lactide-co-glycolide) (PLGA) microspheres which were then dispersed in chitosan thermosensitive gels, Pluronic PF-127 gels, carboxymethylcellulose solutions or Ringer lactate solution. The release rate was assessed in vitro using continuous flow cells and in vivo after intrathecal injection in goats: baclofen was quantified in cerebrospinal fluid (CSF) and plasma, and the associated pharmacological effect was evaluated. The results showed that the burst effect was reduced by at least a factor of 2 in vitro, after microsphere dispersion in viscous media. In vivo, PF-127 gel was found to be the best vehicle to reduce the burst effect by a factor of 10 in CSF, and by a factor of 2 in plasma. The toxic effect of baclofen due to the burst effect was reduced by the dispersion in PF127 gels. Therapeutic levels of baclofen in CSF were maintained during at least 1 month.

Biopharmaceutics of intrathecal baclofen-loaded microparticles in a goat model.

The goal of this study was to develop a goat model allowing reliable pharmacokinetic (PK) studies of intrathecal baclofen (ITB) sustained release dosage forms using an implanted silicone catheter. ITB PK parameters (clearance, volume of distribution) following intrathecal bolus injection were determined for doses ranging from 100 to 560 microg and a comparison to human data was made. Baclofen-loaded microparticles were then implanted in the intrathecal space of goats and the resulting baclofen levels were determined during 28 days. Finally, PK parameters were used to predict cerebrospinal fluid (CSF) baclofen rates from in vitro release profiles of baclofen-loaded microspheres. The catheter was well tolerated and did not interfere with behavioral testings. Baclofen CSF clearance (mean = 8.59+/-2.43 ml/h) and volume of distribution (21.06+/-13.32 ml) were not significantly affected by the increase of the dose (p > 0.05). In vivo, the baclofen levels in CSF were stabilized at 200 microg/l after a period of 3 days. The predictive value of the in vitro release studies was good since the theoretical levels ranged between 128 and 257 microg/l. In conclusion, a large animal model was developed and allowed the biopharmaceutic evaluation of baclofen microparticles injected via intrathecal route.

Use of contrast-enhanced ultrasonography to characterize adrenal gland tumors in dogs.

OBJECTIVE: To describe the contrast-enhanced ultrasonographic characteristics and vascular patterns of adrenal gland tumors in dogs and determine whether those features are indicative of malignancy or histologic type of tumor. ANIMALS: 14 dogs with 16 adrenal gland lesions (10 carcinomas [8 dogs], 3 adenomas [3 dogs], and 3 pheochromocytomas [3 dogs]). PROCEDURES: Unsedated dogs with adrenal gland lesions underwent B-mode ultrasonography and contrast-enhanced ultrasonography ≤ 48 hours before adrenalectomy; contrast-enhanced ultrasonographic examinations were video-recorded. Macroscopic evaluation of the adrenal gland lesions and histologic examination of removed adrenal gland tissues were subsequently performed. Surgical and histopathologic findings and the ultrasonographic and contrast-enhanced ultrasonographic characteristics were recorded for the various tumor types. Time-intensity curves were generated from the contrast-enhanced ultrasonographic recordings and used to calculate regional blood volume (value proportional to area under the curve) and mean transit time (time the lesion began to enhance to the half-peak intensity). RESULTS: In adrenal gland carcinomas, tortuous feeding vessels were noticeable during the arterial and venous phases of contrast enhancement. Heterogeneity of contrast enhancement was evident only in malignant tumors. Compared with adenomas, adrenal gland carcinomas and pheochromocytomas had significantly less regional blood volume. Mean transit times were significantly shorter in adrenal gland carcinomas and pheochromocytomas than in adenomas. CONCLUSIONS AND CLINICAL RELEVANCE: For dogs, evaluation of the vascular pattern and contrast-enhancement characteristics of adrenal gland tumors by means of contrast-enhanced ultrasonography may be useful in assessment of malignancy and tumor type.

Serial magnetic resonance imaging based assessment of the early effects of an ACE inhibitor on postinfarction left ventricular remodeling in rats.

In vivo assessment of treatment efficacy on postinfarct left ventricular (LV) remodeling is crucial for experimental studies. We examined the technical feasibility of serial magnetic resonance imaging (MRI) for monitoring early postinfarct remodeling in rats. MRI studies were performed with a 7-Tesla unit, 1, 3, 8, 15, and 30 days after myocardial infarction (MI) or sham operation, to measure LV mass, volume, and the ejection fraction (EF). Three groups of animals were analyzed: sham-operated rats (n = 6), MI rats receiving lisinopril (n = 11), and MI rats receiving placebo (n = 8). LV dilation occurred on day 3 in both MI groups. LV end-systolic and end-diastolic volumes were significantly lower in lisinopril-treated rats than in placebo-treated rats at days 15 and 30. EF was lower in both MI groups than in the sham group at all time points, and did not differ between the MI groups during follow-up. Less LV hypertrophy was observed in rats receiving lisinopril than in rats receiving placebo at days 15 and 30. We found acceptable within- and between-observer agreement and an excellent correlation between MRI and ex vivo LV mass (r = 0.96; p < 0.001). We demonstrated the ability of MRI to detect the early beneficial impact of angiotensin-converting enzyme (ACE) inhibitors on LV remodeling. Accurate and noninvasive, MRI is the tool of choice to document response to treatment targeting postinfarction LV remodeling in rats.

Potential beneficial as well as detrimental effects of chronic treatment with lisinopril and (or) spironolactone on isolated hearts following low-flow ischemia in normal and infarcted rats.

This study was designed to demonstrate potential beneficial as well as detrimental effects of lisinopril and spironolactone given in combination. In patients with congestive heart failure or myocardial infarction, the use of angiotensin-converting enzyme (ACE) inhibitors may inhibit aldosterone production. Spironolactone, a specific aldosterone receptor antagonist may exert other independent and additive effects to those of ACE inhibitors. Given the consequences of aldosterone on ischemic hearts, we evaluated the protective effects of spironolactone or lisinopril and combined spironolactone-lisinopril therapy during low-flow ischemia and reperfusion in isolated rat hearts. Normal and infarcted (left coronary artery ligature) male Wistar rats were submitted to chronic action of drugs (0.8 mg.kg-1.day-1 for lisinopril and 8 or 50 mg.kg-1.day-1 for spironolactone) for 1 month. Hearts were rapidly excised and perfused (constant pressure) for a 40-min period of stabilization followed by a 25-min period of global low-flow ischemia and a 30-min reperfusion. In normal rats, spironolactone decreased ischemic and reperfusion contracture, reduced ventricular tachycardia, suppressed action-potential duration dispersion, and increased reactive hyperemia leading to an improvement of contractile recovery. Lisinopril also decreased ventricular tachycardia and action-potential duration dispersion concomitantly with increased reactive hyperemia and better contractile recovery. These beneficial effects of the drugs were lost when the two treatments were combined (lisinopril and 50 mg.kg-1.day-1 spironolactone), despite a synergistic effect on plasmatic K+ and Mg2+. However, an interaction between the ACE inhibitor and spironolactone potentiating the effects of either drug alone was observed with a lower dose of spironolactone (lisinopril and 8 mg.kg-1.day-1 spironolactone). Similar beneficial effects have been noted in infarcted rat hearts on reactive hyperemia, ventricular tachycardia, and contractile recovery with the combined treatment and for both spironolactone concentrations (8 or 50 mg). Chronic spironolactone treatment produces similar beneficial effects to ACE inhibitor treatment on normal rat hearts during an ischemia-reperfusion protocol. Synergistic effects have been observed with the combined therapy when a lower dose of spironolactone was utilized in normal and infarcted rats. However, in the case of a high dose of spironolactone, the two effective drugs seem to cancel each other but only in normal rats.

Assessment of myocardial viability in rats: Evaluation of a new method using superparamagnetic iron oxide nanoparticles and Gd-DOTA at high magnetic field.

The aim of this study was to detect salvageable peri-infarction myocardium by MRI in rats after infarction, using with a double contrast agent (CA) protocol at 7 Tesla. Intravascular superparamagnetic iron oxide (SPIO) nanoparticles and an extracellular paramagnetic CA (Gd-DOTA) were used to characterize the peri-infarction zone, which may recover function after reperfusion occurs. Infarcted areas measured from T1-weighted (T1-w) images post Gd-DOTA administration were overestimated compared to histological TTC staining (52% +/- 3% of LV surface area vs. 40% +/- 3%, P=0.03) or to T2-w images post SPIO administration (41% +/- 4%, P=0.04), whereas areas measured from T2-w images post SPIO administration were not significantly different from those measured histologically (P=0.7). Viable and nonviable myocardium portions of ischemically injured myocardium were enhanced after diffusive Gd-DOTA injection. The subsequent injection of vascular SPIO nanoparticles enables the discrimination of viable peri-infarction regions by specifically altering the signal of the still-vascularized myocardium.