Cell-penetrating peptides: a useful tool for the delivery of various cargoes into cells.

Cell-penetrating compounds are substances that enhance the cellular uptake of various molecular cargoes that do not easily cross the cellular membrane. The majority of cell-penetrating compounds described in the literature are cell-penetrating peptides (CPPs). This review summarizes the various structural types of cell-penetrating compounds, with the main focus on CPPs. The authors present a brief overview of the history of CPPs, discuss the various types of conjugation of CPPs to biologically active cargoes intended for cell internalization, examine the cell-entry mechanisms of CPPs, and report on the applications of CPPs in research and in preclinical and clinical studies.

Micelle-forming HPMA copolymer conjugates of ritonavir bound via a pH-sensitive spacer with improved cellular uptake designed for enhanced tumor accumulation.

We describe design, synthesis, physico-chemical characterization and preliminary biological evaluation of micelle-forming polymer drug conjugates with controlled drug release intended for tumor treatment. The structure of the conjugates was designed to enable tumor tissue- and cell-specific drug release and micelle disassembly to avoid side effects accompanying classic chemotherapy and guarantee safe elimination of the drug-free carrier from the organisms. The amphiphilic polymer conjugates consisted of a hydrophobic hexaleucine block and a hydrophilic block based on the N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer with an antiviral and cytostatic drug, ritonavir, bound through a pH-sensitive spacer. Diblock copolymers with low dispersity (D∼ 1.1) were prepared via reversible addition-fragmentation chain transfer (RAFT) copolymerization using a hexaleucine derivative as a chain transfer agent. The associative properties of the copolymers depend on the hydrophilic polymer block length and the hydrophobic ritonavir content. The micelles dissociated under mild acidic conditions mimicking the environment inside tumor tissue/cells, because of the decrease in polymer hydrophobicity after the rapid release of the hydrophobic drug from the polymer carrier. Unexpectedly, the polymer-ritonavir conjugates internalized into HeLa cells significantly more than the polymers without ritonavir. The enhanced cell penetration and pH-triggered micelle disassembly predetermine the polymer-ritonavir conjugates to become promising tumor-targeted drug carriers.

Vinorelbine, epirubicin, and methotrexate (VEM) as primary treatment in locally advanced breast cancer.

PURPOSE: This phase II trial of VEM (vinorelbine + epirubicine + methotrexate) in the treatment of locally advanced breast cancer was conducted to obtain downstaging to allow surgery and breast conservation. PATIENTS AND METHODS: This multicenter study recruited 58 patients with locally advanced breast cancer (two patients ineligible); 56 were evaluable for response and tolerance. RESULTS: Downstaging was obtained in 77% of the patients with a pathological complete response (pCR) rate of 9%. At 33 months of follow-up, median survival has not been reached. Neutropenia grade 3-4 was reported in 31% of cycles with 3% of cycles with infection grade 3. Alopecia grade 3 was noticed for 71% of patients. CONCLUSION: VEM represents an effective regimen for patients with locally advanced breast cancer, allowing an important pCR. Moreover, this regimen appears to be particularly well tolerated.