Activity, reduced toxicity, and scale-up synthesis of amphotericin B-conjugated polysaccharide.

Amphotericin B (AMB) arabinogalactan (AG) conjugate was synthesized by the conjugation of AMB to oxidized AG by reductive amination. The conjugate was evaluated for in vitro antifungal activity and in vivo toxicity. Optimization of the conjugation process was investigated using large batches of 100 g, which are 20 times larger than previously reported for AMB-AG conjugation. The efficacy of AMB-AG conjugates was studied as a function of reaction conditions and time, aldehyde/reducing agent mole ratio, and purification procedure. The most potent AMB-AG conjugate having low minimal inhibitory concentration (MIC) and high maximal tolerated dose (MTD) was obtained following reduction with NaBH4 at 1:2 mol ratio (AG units/NaBH4) at 25 °C for 24 h. AMB-AG conjugate prepared under these conditions demonstrated MIC of 0.5 mg/L (equiv of AMB) in Candida albicans, and an MTD of 60 mg/kg (equiv of AMB) in mice, while AMB clinical formulation (Fungizone) demonstrated high toxicity (MTD = 3 mg/kg). These findings confirm the simplicity and reproducibility of the conjugation allowing this method to be applied on larger scale production.

Toxicity mechanisms of amphotericin B and its neutralization by conjugation with arabinogalactan.

Amphotericin B (AMB) is an effective antifungal agent. However, its therapeutic use is hampered by its toxicity, mainly due to channel formation across kidney cell membranes and the disruption of postendocytic trafficking. We previously described a safe injectable AMB-arabinogalactan (AG) conjugate with neutralized toxicity. Here we studied the mechanism of the toxicity of free AMB and its neutralization by conjugation with AG. AMB treatment of a kidney cell line modulated the trafficking of three receptors (C-X-C chemokine receptor type 4 [CXCR4], M1 receptor, and human transferrin receptor [hTfnR]) due to an increase in endosomal pH. Similar data were also obtained in yeast but with an increase in vacuolar pH and the perturbation of Hxt2-green fluorescent protein (GFP) trafficking. The conjugation of AMB with AG neutralized all elements of the toxic activity of AMB in mammalian but not in fungal cells. Based on these results, we provide an explanation of how the conjugation of AMB with AG neutralizes its toxicity in mammalian cells and add to the knowledge of the mechanism of action of free AMB in both fungal and mammalian cells.

Polysaccharide pharmacokinetics: amphotericin B arabinogalactan conjugate-a drug delivery system or a new pharmaceutical entity?

Conjugation of poorly soluble drugs to polysaccharides affects their solubility, pharmacokinetics (PK), and pharmacodynamics. The need for amphotericin B (AmB) analog with improved solubility and reduced toxicity is immense. Conjugation of AmB to arabinogalactan (AG) produced a highly soluble AmB-AG conjugate, with high and low molecular weight (H-M(w) and L-M(w)) fractions. Its similar antifungal activity to AmB poses the question whether AmB-AG is a prodrug of AmB or a novel pharmaceutical entity. We compared the PK of AmB-AG and AmB in rats. Upon AmB-AG administration, no free AmB was released. The half-lives and the volumes of distribution of AmB, H-M(w) and L-M(w) were 10.9, 8.8, and 1.5 h and 1630, 217, and 133 mL/kg, respectively. We conclude that PK of small molecules conjugated to polysaccharides is mainly dictated by the macromolecular moiety and shows molecular weight dependency. Our findings define AmB-AG as a novel pharmaceutical entity with high clinical potential.

Arabinogalactan-folic acid-drug conjugate for targeted delivery and target-activated release of anticancer drugs to folate receptor-overexpressing cells.

Folic acid (FA) is a high affinity ligand (K(d) = 0.1-1 nM) of folate receptors (FRs) responsible for cellular uptake of folates via receptor-mediated endocytosis. FRs are frequently overexpressed in malignant epithelial cells including ovary, brain, kidney, breast, colon, and lung. FR has emerged as a target for the differential-delivery of anticancer chemotherapeutics with several FA-linked therapeutic agents currently undergoing clinical trials. Here we show that by tethering both FA and the anticancer drug methotrexate (MTX) to arabinogalactan (AG), a highly branched natural polysaccharide with unusual water solubility, a targeted biomacromolecular nanovehicle is formed, which can differentially deliver a cytotoxic cargo into FR-overexpressing cells. Moreover, by linking MTX via an endosomally cleavable peptide (GFLG), we demonstrate a target-activated release mechanism. This FA-AG-GFLG-MTX drug conjugate displayed 6.3-fold increased cytotoxic activity to FR-overexpressing cells compared to their FR-lacking counterparts. These findings establish a novel FA-tethered polymeric nanoconjugate for the targeted delivery of antitumor agents into cancer cells overexpressing FR.

Resection of Cervical Juxtacortical Chondroma and Circumferential Spinal Stabilization for Kyphotic Deformity.

Chondromas are rare, benign tumors composed of cartilaginous tissue that mainly affect the metaphases of long tubular bones. Juxtacortical (periosteal) chondromas arise from the surface of periosteum and rarely affect the cervical spine. We present a patient with a spinal juxtacortical chondroma causing spinal cord compression and a cervical deformity treated with surgical resection and circumferential spinal fixation and stabilization. A 55-year-old female with past medical history of Crohn's disease with years of neck pain, balance issues, and left upper extremity radicular symptoms. Cervical spine x-rays show kyphosis with an apex at C5, degenerative changes of the endplates and facet joints, and grade 2 anterolisthesis C4 on C5 with no abnormal motion with flexion/extension. MRI showed a left sided C5-6 extramedullary mass measuring 11 x 11 x 15 mm causing spinal cord compression and neural foraminal narrowing. Her pain is worsening and refractory to physical therapy, gabapentin and methocarbamol. A C4-5 & C5-6 anterior cervical discectomy and fusion, C4-5 & C5-6 laminectomy for tumor resection, and C4-5 & C5-6 posterior fusion with instrumentation was performed. The tumor was completely removed in piecemeal fashion. Microscopic findings showed bland well differentiated cartilaginous neoplasm consistent with juxtacortical chondroma. Postoperative X-rays show partial reduction of C4-5 anterolisthesis and partial reversal of cervical kyphosis. The patient's radicular pain resolved and neck pain improved postoperatively but she still has some left sided neck pain and hand dysesthesias that are controlled with oral medication one year following surgery. Cervical chondromas are rare, benign cartilaginous tumors that may present with spinal cord or nerve root compression. They are more complex when they present in patients with co-existing spinal deformities. Maximal safe resection followed by spinal re-alignment and fixation without adjuvant chemotherapy or radiation is recommended in most cases. Close follow-up is recommended to monitor for recurrence.

Long-Term Assessment of Fibromyalgia in Patients with Culture-Confirmed Lyme Disease.

Background: Fibromyalgia occurs in 2% to 8% of the general population. One of the triggers may be Lyme disease. Methods: Patients with culture-confirmed Lyme disease who originally presented with erythema migrans have been evaluated annually in a prospective study to determine their long-term outcome. In 2011-2013, subjects were evaluated for fibromyalgia by interview and tender point examination. Results: 100 subjects were assessed, 52% of whom were male; the mean age was 64.9 years (median 64 years, range 42-86 years). The mean duration of follow-up was 15.4 years (median 16 years, range 11-20 years). At least twenty-four (24%) subjects had experienced a second episode of erythema migrans before the evaluation for fibromyalgia. One patient (1%, 95% C.I.: 0.025 to 5.4%) met criteria for fibromyalgia. The symptoms consistent with fibromyalgia began more than 19 years after Lyme disease was diagnosed. Conclusions: Fibromyalgia was observed in only 1% of 100 patients with culture-confirmed early Lyme disease, a frequency consistent with that found for the general population. This article is protected by copyright. All rights reserved.

High plasma levels and effective lymphatic uptake of docetaxel in an orally available nanotransporter formulation.

Docetaxel, an efficient chemotherapeutic drug, exhibits low and variable oral bioavailability due to the active efflux by P-glycoprotein (P-gp) and more so to CYP3A4 gut metabolism. Using a spray-drying technique, docetaxel was incorporated in PLGA [poly(lactic-co-glycolic acid)] nanocapsules (NC) which were embedded in entero-coated microparticles. An oral administration of the NC formulation elicited a higher absolute bioavailability than both a docetaxel solution (276%) and a free docetaxel NC formulation (400%) injected intravenously, a 5-mg/kg dose. The batches (B) I and II NC formulations elicited C(max) values that were 1,735% and 2,254%, respectively; higher than the C(max) value of the oral docetaxel solution combined with blank microparticles, a 10-mg/kg dose. No significant difference in AUC (area under curve) was observed between the batches. These unexpected results can be explained only if the pharmacokinetics of docetaxel had been modified. It was shown that NCs released from the microparticles penetrated the enterocytes, bypassing P-gp; apparently circumventing gut metabolism and accumulating within the lymphatic system from where both intact or biodegraded NCs and free docetaxel were progressively released into the circulation as plausibly supported by the fluorescent imaging results. Furthermore, the circulating docetaxel in plasma was unencapsulated and circulated either in free form or bound to albumin. Both free docetaxel NCs and microparticles exhibited in vitro efficacy on WRC 256 cells suggesting that the activity of docetaxel was not altered. This delivery concept has potential for clinical translation, perhaps allowing docetaxel chemotherapy to be switched from intravenous to oral delivery.