Comparisons of biophysical properties and bioactivities of mono-PEGylated endostatin and an endostatin analog

Quality, bioactivity study, and preclinical acute toxicity, safety pharmacology evaluation of PEGylated recombinant human endostatin (M2 ES)

Endostar, a potent endogenous antiangiogenic factor, is wildly used in clinics. However, it was easily degraded by enzymes and rapidly cleared by the kidneys. To overcome these shortcomings, PEGylated recombinant human endostatin was developed. In this study, the purity of M₂ ES was evaluated by silver stain and reversed-phase high-performance liquid chromatography. Ultraviolet spectrum was used to examine the structural of M₂ ES and endostar. The bioactivity and antitumor efficacy of M₂ ES were evaluated using an in vitro endothelial cell migration model and athymic nude mouse xenograft model of a heterogeneous lung adenocarcinoma, respectively. A preclinical study was performed to evaluate the acute toxicity and safety pharmacology in rhesus monkeys. The purity of M₂ ES was more than 98%; PEG modification has no effect on endostatin structure. Compared with the control group, M₂ ES dramatically retards endothelial cell migration and tumor growth. After intravenous (IV) infusions of M₂ ES at a dose level of three and 75 mg/kg in rhesus monkeys, there was no observable serious adverse event in both acute toxicity and safety pharmacology study. On the basis of the quality and bioactivity study data of M₂ ES and the absence of serious side effect in rhesus monkeys, M₂ ES was authorized to initiate a phase I clinical trial.

Twenty years after: the beautiful hypothesis and the ugly facts

The limited clinical benefits from current antiangiogenic therapy for cancer patients have triggered some critical thoughts and insightful investigations aiming to further elucidate the relationship between vessels and cancer. Tumors need blood perfusion but there are mounting evidences that angiogenesis alone does not explain it in all the neoplasms. In this editorial, for a special issue on tumor and vessels published in the Chinese Journal of Cancer, we briefly introduce the history of the evidences that solid tumors can sometimes obtain blood perfusion by alternative approaches other than sprouting angiogenesis, i.e., vessel co-option and vasculogenic mimicry. This editorial provides also the links to several most recently published discoveries and hypotheses on tumor interaction with blood vessels.