Preclinical evaluation of local prolonged release of paclitaxel from gelatin microspheres for the prevention of recurrence of peritoneal carcinomatosis in advanced ovarian cancer

Patients with advanced ovarian cancer develop recurrence despite initial treatment response to standard treatment of surgery and intravenous/intraperitoneal (IP) chemotherapy, partly due to a limited peritoneal exposure time of chemotherapeutics. Paclitaxel-loaded genipin-crosslinked gelatin microspheres (PTX-GP-MS) are evaluated for the treatment of microscopic peritoneal carcinomatosis and prevention of recurrent disease. The highest drug load (39.2 mu g PTX/mg MS) was obtained by immersion of GP-MS in aqueous PTX nanosuspension (PTXnano-GP-MS) instead of ethanolic PTX solution (PTXEtOH-GP-MS). PTX release from PTX-GP-MS was prolonged. PTXnano-GP-MS displayed a more controlled release compared to a biphasic release from PTX-GP-MS. Anticancer efficacy of IP PTX-GP-MS (PTXEtOH-GP-MS, D = 7.5 mg PTX/kg; PTXnano-GP-MS D= 7.5 and 35 mg PTX/kg), IP nanoparticular albumin-bound PTX (D = 35 mg PTX/kg) and controls (0.9% NaCl, blank GP-MS) was evaluated in a microscopic peritoneal carcinomatosis xenograft mouse model. PTXnano-GP-MS showed superior anticancer efficacy with significant increased survival time, decreased peritoneal carcinomatosis index score and ascites incidence. However, prolonged PTX release over 14 days from PTXnano-GP-MS caused drug-related toxicity in 27% of high-dosed PTXnano-GP-MS-treated mice. Dose simulations for PTXnano-GP-MS demonstrated an optimal survival without drug-induced toxicity in a range of 7.5-15 mg PTX/kg. Low-dosed PTXnano-GP-MS can be a promising IP drug delivery system to prevent recurrent ovarian cancer

Establishment of a rat ovarian peritoneal metastasis model to study pressurized intraperitoneal aerosol chemotherapy (PIPAC)

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A nanobody modulates the p53 transcriptional program without perturbing its functional architecture

The p53 transcription factor plays an important role in genome integrity. To perform this task, p53 regulates the transcription of genes promoting various cellular outcomes including cell cycle arrest, apoptosis or senescence. The precise regulation of this activity remains elusive as numerous mechanisms, e.g. posttranslational modifications of p53 and (non-)covalent p53 binding partners, influence the p53 transcriptional program. We developed a novel, non-invasive tool to manipulate endogenous p53. Nanobodies (Nb), raised against the DNA-binding domain of p53, allow us to distinctively target both wild type and mutant p53 with great specificity. Nb3 preferentially binds ‘structural’ mutant p53, i.e. R175H and R282W, while a second but distinct nanobody, Nb139, binds both mutant and wild type p53. The co-crystal structure of the p53 DNA-binding domain in complex with Nb139 (1.9 Å resolution) reveals that Nb139 binds opposite the DNA-binding surface. Furthermore, we demonstrate that Nb139 does not disturb the functional architecture of the p53 DNA-binding domain using conformation-specific p53 antibody immunoprecipitations, glutaraldehyde crosslinking assays and chromatin immunoprecipitation. Functionally, the binding of Nb139 to p53 allows us to perturb the transactivation of p53 target genes. We propose that reduced recruitment of transcriptional co-activators or modulation of selected post-transcriptional modifications account for these observations

Power Doppler ultrasound and contrast-enhanced ultrasound demonstrate non-invasive tumour vascular response to anti-vascular therapy in canine cancer patients

Combretastatin A4-phosphate (CA4P) is an anti-vascular agent which selectively shuts down blood supply in tumours, resulting in extensive tumour necrosis. The aim of this study was to assess in vivo, non-invasive ultrasound techniques for the early evaluation of tumour perfusion following CA4P treatment of spontaneous tumours. Eight dogs that bore spontaneous tumours were enrolled and were subsequently treated with a single dose of intravenous CA4P. Perfusion of tumours was evaluated by power Doppler ultrasound (PDUS) pre-treatment (0 h), during the injection (10 min, 20 min, 30 min) and after CA4P infusion (24 and 72 h). Vascularity index (VI) of the tumour tissue was quantitatively analysed and accuracy was verified by correlation analysis with the results of immunohistochemical evaluation of microvessel density (MVD). Central and peripheral perfusion was evaluated by contrast-enhanced ultrasound (CEUS) pre-treatment and at 72 h post-treatment. Post-treatment, PDUS demonstrated a significant decrease in VI within 10 min of CA4P infusion. CEUS parameters demonstrated a significant decrease in blood velocity and volume in the central aspect of the tumour. Histology revealed a 4.4-fold reduction (p < 0.001, 95% CI [2.2,9.4]) in MVD and a 4.1-fold increase (p = 0.003, 95% CI [1.4,11.8]) in necrotic tumour tissue. A strong correlation between PDUS results and immunohistochemical results was found (Pearson R-2 = 0.957, p < 0.001). Furthermore, the findings of PDUS were supported by the objective results of the CEUS analyses. These data suggest a role for ultrasound in real-time, non-invasive monitoring of tumour vascular response as an early indicator of CA4P treatment efficacy

Model-based analysis of treatment effects of paclitaxel microspheres in a microscopic peritoneal carcinomatosis model in mice

PurposePaclitaxel (PTX)-loaded genipin-crosslinked gelatin microspheres (GP-MS) are a prolonged IP delivery system under development for the treatment of peritoneal minimal residual disease (pMRD). Here, we show the use of a pharmacokinetic-pharmacodynamic (PKPD) modelling approach to inform the formulation development of PTX-GP-MS in a mice pMRD model.MethodsPTX blood concentrations and survival data were obtained in Balb/c Nu mice receiving different single IP doses (7.5 and/or 35 mg/kg) of PTX-ethanolic loaded GP-MS (PTXEtOH-GP-MS), PTX-nanosuspension loaded GP-MS (PTXnano-GP-MS), and immediate release formulation Abraxane (R). A population PK model was developed to characterize the PTX blood concentration pattern and to predict PTX concentrations in peritoneum. Afterwards, PKPD relationships between the predicted peritoneal or blood concentrations and survival were explored using time-to-event modelling.ResultsA PKPD model was developed that simultaneously describes the competing effects of treatment efficacy (driven by peritoneal concentration) and toxicity (driven by blood concentration) of PTX on survival. Clear survival advantages of PTXnano-GP-MS over PTXEtOH-GP-MS and Abraxane (R) were found. Simulations of different doses of PTXnano-GP-MS demonstrated that drug-induced toxicity is high at doses between 20 and 35 mg/kg.ConclusionsThe model predicts that the dose range of 7.5-15 mg/kg of PTXnano-GP-MS provides an optimal balance between efficacy and safety

A dose-escalation study of combretastatin A4-phosphate in healthy dogs

Combretastatin A4-Phosphate (CA4P) is a vascular disrupting agent revealing promising results in cancer treatments for humans. The aim of this study was to investigate the safety and adverse events of CA4P in healthy dogs as a prerequisite to application of CA4P in dogs with cancer. Ten healthy dogs were included. The effects of escalating doses of CA4P on physical, haematological and biochemical parameters, systolic arterial blood pressure, electrocardiogram, echocardiographic variables and general wellbeing were characterised. Three different doses were tested: 50, 75 and 100mgm(-2). At all 3 CA4P doses, nausea, abdominal discomfort as well as diarrhoea were observed for several hours following administration. Likewise, a low-grade neutropenia was observed in all dogs. Doses of 75 and 100mgm(-2) additionally induced vomiting and elevation of serum cardiac troponine I levels. At 100mgm(-2), low-grade hypertension and high-grade neurotoxicity were also observed. In healthy dogs, doses up to 75mgm(-2) seem to be well tolerated. The severity of the neurotoxicity observed at 100mgm(-2), although transient, does not invite to use this dose in canine oncology patients

Power Doppler ultrasound and contrast-enhanced ultrasound demonstrate non-invasive tumour vascular response to anti-vascular therapy in canine cancer patients

Combretastatin A4-phosphate (CA4P) is an anti-vascular agent which selectively shuts down blood supply in tumours, resulting in extensive tumour necrosis. The aim of this study was to assess in vivo, non-invasive ultrasound techniques for the early evaluation of tumour perfusion following CA4P treatment of spontaneous tumours. Eight dogs that bore spontaneous tumours were enrolled and were subsequently treated with a single dose of intravenous CA4P. Perfusion of tumours was evaluated by power Doppler ultrasound (PDUS) pre-treatment (0 h), during the injection (10 min, 20 min, 30 min) and after CA4P infusion (24 and 72 h). Vascularity index (VI) of the tumour tissue was quantitatively analysed and accuracy was verified by correlation analysis with the results of immunohistochemical evaluation of microvessel density (MVD). Central and peripheral perfusion was evaluated by contrast-enhanced ultrasound (CEUS) pre-treatment and at 72 h post-treatment. Post-treatment, PDUS demonstrated a significant decrease in VI within 10 min of CA4P infusion. CEUS parameters demonstrated a significant decrease in blood velocity and volume in the central aspect of the tumour. Histology revealed a 4.4-fold reduction (p < 0.001, 95% CI [2.2,9.4]) in MVD and a 4.1-fold increase (p = 0.003, 95% CI [1.4,11.8]) in necrotic tumour tissue. A strong correlation between PDUS results and immunohistochemical results was found (Pearson R2 = 0.957, p < 0.001). Furthermore, the findings of PDUS were supported by the objective results of the CEUS analyses. These data suggest a role for ultrasound in real-time, non-invasive monitoring of tumour vascular response as an early indicator of CA4P treatment efficacy.status: publishe