Regorafenib, an investigational agent for the treatment of cholangiocarcinoma.

INTRODUCTION: Cholangiocarcinoma is a prevalent gastrointestinal cancer with a high mortality rate. A limited number of cholangiocarcinoma patients are diagnosed with early-stage disease but unfortunately, most patients present with an advanced-stage disease which is not amenable to curative surgical resection. AREAS COVERED: We discuss regorafenib, a multi-kinase inhibitor, which has been investigated as a therapeutic agent in advanced stage biliary tract cancer patients in phase II trials. We examined the efficacy and toxicity of this agent and its potential in this patient population in the future. We also provide further insights on novel approaches to optimize the efficacy of regorafenib in cholangiocarcinoma patients. EXPERT OPINION: The recent phase II trials of single-agent regorafenib in advanced stage biliary tumors revealed a modest activity in non enriched patient population and is currently part of the national comprehensive cancer network (NCCN) guidelines (Level 2B) in the refractory setting. However, more opportunities for this agent exist in combination approaches with other therapeutics such as immune checkpoint inhibitors. It is also important to recognize that the paradigm has significantly shifted for targeted therapy to more specific and more potent tyrosine kinase inhibitors targeting specific actionable genes.

Herb-induced cardiotoxicity from accidental aconitine overdose.

Patients who overdose on aconite can present with life-threatening ventricular arrhythmia. Aconite must be prepared and used with caution to avoid cardiotoxic effects that can be fatal. We herein describe a case of a patient who had an accidental aconite overdose but survived with no lasting effects. The patient had prepared Chinese herbal medication to treat his pain, which resulted in an accidental overdose of aconite with cardiotoxic and neurotoxic effects. The patient had ventricular tachycardia, bidirectional ventricular tachycardia and ventricular fibrillation. Following treatment with anti-arrhythmic medications, defibrillation and cardiopulmonary resuscitation, he made an uneventful recovery, with no further cardiac arrhythmias reported.

Development of a cell transducible RhoA inhibitor TAT-C3 transferase and its encapsulation in biocompatible microspheres to promote survival and enhance regeneration of severed neurons.

PURPOSE: Neurons in post-traumatized mammalian central nervous system show only limited degree of regeneration, which can be attributed to the presence of neurite outgrowth inhibitors in damaged myelin and glial scar, and to the apoptosis of severed central neurons and glial cells during secondary Wallerian degeneration. RhoA GTPase has been implicated as the common denominator in these counter-regeneration events, which shows significant and persistent up-regulation for weeks in injured spinal cord and cerebral infarct after stroke. While the exoenzyme C3 transferase is a potent RhoA inhibitor, its extremely low efficiency of cell entry and degradation in vivo has restricted the therapeutic value. This study aims to circumvent these problems by developing a membrane-permeating form of C3 transferase and a biopolymer-based microsphere depot system for sustainable controlled release of the protein. MATERIALS AND METHODS: A membrane-permeating form of C3 transferase was developed by fusing a Tat (trans-activating transcription factor) transduction domain of human immunodeficiency virus to its amino terminal using standard molecular cloning techniques. After confirming efficient cell entry into epithelial and neuroblastoma cells, the resulting recombinant protein TAT-C3 was encapsulated in biocompatible polymer poly(D,L -lactide-co-glycolide) in the form of microspheres by a water-in-oil-in-water (W/O/W) emulsion method. By blending capped and uncapped form of the polymer at different ratios, TAT-C3 protein release profile was modified to suit the expression pattern of endogenous RhoA during CNS injuries. Bioactivity of TAT-C3 released from microspheres was assessed by RhoA ribosylation assay. RESULTS: In contrast to wild-type C3 transferase, the modified TAT-C3 protein was found to efficiently enter NIH3T3 and N1E-115 neuroblastoma cells as early as 6 hours of incubation. The fusion of TAT sequence to C3 transferase imposed no appreciable effects on its biological activity in promoting neurite outgrowth through RhoA inhibition. Characterization of TAT-C3 encapsulation in various blends of capped/uncapped PLGA polymer revealed the 30:70 formulation to be optimal in attaining a mild initial burst release of 25%, followed by a subsequent average daily release of 2.3% of encapsulated protein over one month, matching the change in RhoA level in severed brain and spinal cord. Importantly, TAT-C3 released from the microspheres remained active up to the first three weeks of incubation. CONCLUSION: Enhanced cell entry of TAT-C3 circumvents the need to administer high dose of the protein to site of injury. The encapsulation of TAT-C3 in different blends of capped/uncapped PLGA microspheres allows adjustment of protein release profile to suit the pattern of RhoA expression in injured CNS.