Yechezkel Barenholz

Bio: Yechezkel Barenholz is an academic researcher from Hebrew University of Jerusalem. The author has contributed to research in topics: Liposome & Phospholipid. The author has an hindex of 44, co-authored 81 publications receiving 16324 citations. Previous affiliations of Yechezkel Barenholz include Alza & Weizmann Institute of Science.

Prolonged circulation time and enhanced accumulation in malignant exudates of doxorubicin encapsulated in polyethylene-glycol coated liposomes.

Abstract: In preclinical studies, a doxorubicin liposome formulation containing polyethylene-glycol (Doxil) shows a long circulation time in plasma, enhanced accumulation in murine tumors, and a superior therapeutic activity over free (unencapsulated) doxorubicin (DOX). The purpose of this study was to characterize the pharmacokinetics of Doxil in cancer patients in comparison with free DOX and examine its accumulation in malignant effusions. The pharmacokinetics of doxorubicin and/or liposome-associated doxorubicin were analyzed in seven patients after injections of equivalent doses of free DOX and Doxil and in an additional group of nine patients after injection of Doxil only. Two dose levels were examined, 25 and 50 mg/m2. When possible, drug levels were also measured in malignant effusions. The plasma elimination of Doxil followed a biexponential curve with half-lives of 2 and 45 h (median values), most of the dose being cleared from plasma under the longer half-life. Nearly 100% of the drug detected in plasma after Doxil injection was in liposome-encapsulated form. A slow plasma clearance (0.1 liter/h for Doxil versus 45 liters/h for free DOX) and a small volume of distribution (4 liters for Doxil versus 254 liters for free DOX) are characteristic of Doxil. Doxorubicin metabolites were detected in the urine of Doxil-treated patients with a pattern similar to that reported for free DOX, although the overall urinary excretion of drug and metabolites was significantly reduced. Doxil treatment resulted in a 4- to 16-fold enhancement of drug levels in malignant effusions, peaking between 3 to 7 days after injection. Stomatitis related to Doxil occurred in 5 of 15 evaluable patients and appears to be the most significant side effect in heavily pretreated patients. The results of this study are consistent with preclinical findings indicating that the pharmacokinetics of doxorubicin are drastically altered using Doxil and follow a pattern dictated by the liposome carrier. The enhanced drug accumulation in malignant effusions is apparently related to liposome longevity in circulation. Further clinical investigation is needed to establish the relevance of these findings with regard to the ability of liposomes to modify the delivery of doxorubicin to solid tumors and its pattern of antitumor activity.

Nanocarriers as an emerging platform for cancer therapy

Abstract: Nanotechnology has the potential to revolutionize cancer diagnosis and therapy. Advances in protein engineering and materials science have contributed to novel nanoscale targeting approaches that may bring new hope to cancer patients. Several therapeutic nanocarriers have been approved for clinical use. However, to date, there are only a few clinically approved nanocarriers that incorporate molecules to selectively bind and target cancer cells. This review examines some of the approved formulations and discusses the challenges in translating basic research to the clinic. We detail the arsenal of nanocarriers and molecules available for selective tumour targeting, and emphasize the challenges in cancer treatment.

Stimuli-responsive nanocarriers for drug delivery

Abstract: Spurred by recent progress in materials chemistry and drug delivery, stimuli-responsive devices that deliver a drug in spatial-, temporal- and dosage-controlled fashions have become possible. Implementation of such devices requires the use of biocompatible materials that are susceptible to a specific physical incitement or that, in response to a specific stimulus, undergo a protonation, a hydrolytic cleavage or a (supra)molecular conformational change. In this Review, we discuss recent advances in the design of nanoscale stimuli-responsive systems that are able to control drug biodistribution in response to specific stimuli, either exogenous (variations in temperature, magnetic field, ultrasound intensity, light or electric pulses) or endogenous (changes in pH, enzyme concentration or redox gradients).

Principles of nanoparticle design for overcoming biological barriers to drug delivery

Abstract: Biological barriers to drug transport prevent successful accumulation of nanotherapeutics specifically at diseased sites, limiting efficacious responses in disease processes ranging from cancer to inflammation. Although substantial research efforts have aimed to incorporate multiple functionalities and moieties within the overall nanoparticle design, many of these strategies fail to adequately address these barriers. Obstacles, such as nonspecific distribution and inadequate accumulation of therapeutics, remain formidable challenges to drug developers. A reimagining of conventional nanoparticles is needed to successfully negotiate these impediments to drug delivery. Site-specific delivery of therapeutics will remain a distant reality unless nanocarrier design takes into account the majority, if not all, of the biological barriers that a particle encounters upon intravenous administration. By successively addressing each of these barriers, innovative design features can be rationally incorporated that will create a new generation of nanotherapeutics, realizing a paradigmatic shift in nanoparticle-based drug delivery.

Cancer nanomedicine: progress, challenges and opportunities.

Abstract: The intrinsic limits of conventional cancer therapies prompted the development and application of various nanotechnologies for more effective and safer cancer treatment, herein referred to as cancer nanomedicine. Considerable technological success has been achieved in this field, but the main obstacles to nanomedicine becoming a new paradigm in cancer therapy stem from the complexities and heterogeneity of tumour biology, an incomplete understanding of nano-bio interactions and the challenges regarding chemistry, manufacturing and controls required for clinical translation and commercialization. This Review highlights the progress, challenges and opportunities in cancer nanomedicine and discusses novel engineering approaches that capitalize on our growing understanding of tumour biology and nano-bio interactions to develop more effective nanotherapeutics for cancer patients.