Novel engineered TRAIL-based chimeric protein strongly inhibits tumor growth and bypasses TRAIL resistance.

Targeting of the TRAIL-DR4/5 pathway was proposed as a promising approach for specific induction of apoptosis in cancer cells. Clinical trials, however, showed inadequate efficiency of TRAIL as a monotherapy. It is a widely held view that the application of multifunctional molecules or combination therapy may lead to substantial improvement. Here, we demonstrate the effectiveness and safety of a novel chimeric protein, AD-O51.4, which is a TRAIL equipped with positively charged VEGFA-derived effector peptides. The study was performed in multiple cancer cell line- and patient-derived xenografts. A pharmacokinetic profile was established in monkeys. AD-O51.4 strongly inhibits tumor growth, even leading to complete long-term tumor remission. Neither mice nor monkeys treated with AD-O51.4 demonstrate symptoms of drug toxicity. AD-O51.4 exhibits a satisfactory half-life in plasma and accumulates preferentially in tumors. The cellular mechanism of AD-O51.4 activity involves both cytotoxic effects in tumor cells and antiangiogenic effects on the endothelium. The presence of DRs in cancer cells is crucial for AD-O51.4-driven apoptosis execution. The TRAIL component of the fusion molecule serves as an apoptosis inducer and a cellular anchor for the effector peptides in TRAIL-sensitive and TRAIL-resistant cancer cells, respectively. The FADD-dependent pathway, however, seems to be not indispensable in death signal transduction; thus, AD-O51.4 is capable of bypassing the refractoriness of TRAIL. AD-O51.4-driven cell death, which exceeds TRAIL activity, is achieved due to the N-terminally fused polypeptide, containing VEGFA-derived effector peptides. The high anticancer efficiency of AD-O51.4 combined with its safety has led to the entry of AD-O51.4 into toxicological studies.

AD-O53.2--a novel recombinant fusion protein combining the activities of TRAIL/Apo2L and Smac/Diablo, overcomes resistance of human cancer cells to TRAIL/Apo2L.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and its receptors became promising molecules for selective targeting of tumor cells without affecting normal tissue. Unfortunately, cancer cells have developed a number of mechanisms that confer resistance to TRAIL\Apo2L-induced apoptosis, which substantiates the need for development of alternative therapeutic strategies. Here we present a recombinant variant of TRAIL\Apo2L peptide, named AD-O53.2, fused to the peptide-derived from Smac/Diablo protein-the natural inhibitor of the apoptotic X-linked IAP (XIAP) protein considered as a pro-apoptotic agent. The proposed mechanism of action for this construct involves specific targeting of the tumor by TRAIL\Apo2L followed by activation and internalization of pro-apoptotic peptide into the cancer cells. While in the cytoplasm , the Smac\Diablo peptide inhibits activity of X-linked IAP (XIAP) proteins and promotes caspase-mediated apoptosis. AD-O53.2 construct was expressed in E.coli and purified by Ion Exchange Chromatography (IEC). Derived protein was initially characterized by circular dichroism spectroscopy (CD), HPLC-SEC chromatography, surface plasmon resonance, protease activation and cell proliferation assays. Our Smac/Diablo-TRAIL fusion variant was tested against a panel of cancer cells (including lung, colorectal, pancreatic, liver, kidney and uterine) and showed a potent cytotoxic effect with the IC50 values in femtomolar range for the most sensitive cell lines, while it remained ineffective against non-transformed HUVEC cells as well as isolated normal human and rat hepatocytes. Importantly, the construct was well tolerated by animals and significantly reduced the rate of the tumor growth in colon and lung adenocarcinoma animal models.

Structural factors affecting cytotoxic activity of (E)-1-(Benzo[d ][1,3]oxathiol-6-yl)-3-phenylprop-2-en-1-one derivatives.

Derivatives of (E)-1-(5-alkoxybenzo[d][1,3]oxathiol-6-yl)-3-phenylprop-2-en-1-one demonstrated exceptionally high in vitro cytotoxic activity, with IC50 values of the most active derivatives in the nanomolar range. To identify structural fragments necessary for the activity, several analogs deprived of selected fragments were prepared, and their cytotoxic activity was tested. It was found that the activity depends on combined effects of (i) the heterocyclic ring, (ii) the alkoxy group at position 5 of the benzoxathiole ring, and (iii) the substituents in the phenyl ring B. Replacement of the sulfur atom by oxygen does not influence the activity. None of the listed structural fragments alone assured high cytotoxic activity.