TRAIL (TNF-related apoptosis-inducing ligand) and its derivatives are potentials for anticancer therapy due to the selective induction of apoptosis in tumor cells upon binding to death receptors DR4 or DR5. Previously, we generated a DR5-selective TRAIL mutant variant DR5-B overcoming receptor-dependent resistance of tumor cells to TRAIL. In the current study, we improved the antitumor activity of DR5-B by fusion with a tumor-homing iRGD peptide, which is known to enhance the drug penetration into tumor tissues. The obtained bispecific fusion protein DR5-B-iRGD exhibited dual affinity for DR5 and integrin αvβ3 receptors. DR5-B-iRGD penetrated into U-87 tumor spheroids faster than DR5-B and demonstrated an enhanced antitumor effect in human glioblastoma cell lines T98G and U-87, as well as in primary patient-derived glioblastoma neurospheres in vitro. Additionally, DR5-B-iRGD was highly effective in a xenograft mouse model of the U-87 human glioblastoma cell line in vivo. We suggest that DR5-B-iRGD may become a promising candidate for targeted therapy for glioblastoma.

The development of therapeutic bispecific antibodies and hybrid proteins is one of the most urgent biomedical technologies with obvious clinical prospects. At the same time, advanced strategies of molecular design of drugs with new properties are coming to the forefront. The tumour necrosis factor-related apoptosis inducing ligand (TRAIL) receptor pathways are important components of the immune system involved in the immune surveillance and selective elimination of transformed cells. TRAIL-based proteins are therefore promising drug candidates for the treatment of malignant tumours and autoimmune diseases. In the first series of clinical trials, drugs targeting the death receptors DR4 or DR5, did not show significant anti-cancer activity. This is due to the TRAIL resistance mechanisms that tumours evolve to evade the efficient induction of apoptotic signalling. However, a wide range of novel TRAIL death receptor-targeted formulations are currently being developed, mainly to improve stability, enhance death receptor clustering and involve additional tumour targets. Over the past decade, several dozens of multi-targeted fusion proteins with either TRAIL protein or DR5-specific agonistic monoclonal antibodies have been developed to improve therapeutic efficacy. These include fusions with either short peptide tags or large functional proteins, as well as antibody fragments targeting molecular pathways involved in angiogenesis or proliferative signalling such as epidermal growth factor receptor (EGFR), vascular endothelial growth factor receptor (VEGFR), programmed death-ligand 1 (PD-L1), etc. Collectively, these multimodal proteins enhance the activation of extrinsic and intrinsic apoptotic pathways in transformed cells, as well as affect the tumour microenvironment. This comprehensive review systematizes the bispecific and multivalent fusion proteins and conjugates targeting TRAIL death receptors, analyze the molecular mechanisms by which they overcome tumour resistance to TRAIL, and assess their clinical prospects.The bibliography includes 236 references.

In the last two decades, bifunctional proteins have been created by genetic and protein engineering methods to increase therapeutic effects in various diseases, including cancer. Unlike conventional small molecule or monotargeted drugs, bifunctional proteins have increased biological activity while maintaining low systemic toxicity. The recombinant anti-cancer cytokine TRAIL has shown a limited therapeutic effect in clinical trials. To enhance the efficacy of TRAIL, we designed the HRH–DR5-B fusion protein based on the DR5-selective mutant variant of TRAIL fused to the anti-angiogenic synthetic peptide HRHTKQRHTALH. Initially low expression of HRH–DR5-B was enhanced by the substitution of E. coli-optimized codons with AT-rich codons in the DNA sequence encoding the first 7 amino acid residues of the HRH peptide. However, the HRH–DR5-B degraded during purification to form two adjacent protein bands on the SDS-PAGE gel. The replacement of His by Ser at position P2 immediately after the initiator Met dramatically minimized degradation, allowing more than 20 mg of protein to be obtained from 200 mL of cell culture. The resulting SRH–DR5-B fusion bound the VEGFR2 and DR5 receptors with high affinity and showed increased cytotoxic activity in 3D multicellular tumor spheroids. SRH–DR5-B can be considered as a promising candidate for therapeutic applications.

A promising strategy for pancreatic cancer therapy involves developing nanocarriers capable of simultaneously delivering various antitumor substances with diverse physicochemical properties, often resulting in synergistic effects. In the present work, novel biocomposites were developed using amphiphilic N-vinylpyrrolidone polymer incorporating bortezomib (BTZ) and modified with either the DR5-selective TRAIL cytokine (DR5-B) or its fusion with the iRGD effector peptide (DR5-B-iRGD), resulting in AmphPVP-BTZ-DR5-B and AmphPVP-BTZ-DR5-B-iRGD formulations. The release of BTZ was most extensive at acidic pH 5.6, mimicking endolysosomal compartments, while at near-neutral pH 7.4 and alkaline pH 8.2 the release was slower and less complete, indicating a smart pH-responsive behavior suitable for triggered release in the tumor microenvironment. Both AmphPVP-BTZ-DR5-B and AmphPVP-BTZ-DR5-B-iRGD significantly inhibited the growth of pancreatic adenocarcinoma cell lines PANC-1, BxPC-3, and MIA PaCa-2 and induced more rapid internalization of the DR5 receptor in MIA PaCa-2 cells than unmodified particles and free DR5-B or DR5-B-iRGD. Importantly, AmphPVP-BTZ-DR5-B-iRGD exhibited a more pronounced DR5 internalization rate and cytotoxic effect than AmphPVP-BTZ-DR5-B owing to the presence of fusion protein with internalizing iRGD peptide. Both biocomposites induced cell death via the apoptotic pathway while exhibiting minimal cytotoxic effects on healthy cells. Therefore, biocomposites incorporating BTZ and functionalized with DR5-selective TRAIL variants DR5-B or DR5-B-iRGD represent a promising avenue for future studies in pancreatic cancer animal models.

Pancreatic adenocarcinoma is one of the most aggressive cancers. Its treatment relies on conventional chemotherapy agents; particularly gemcitabine. Chemotherapy is known to induce cell cycle arrest and the development of a senescent phenotype in tumor cells. The accumulation of senescent cells limits tumor proliferation, followed by the secretion of factors of the senescence-associated secretory phenotype promoting malignancy in the tumor microenvironment and metastasis. This makes the search for drugs suitable for senolytic therapy highly relevant. This study explored the senolytic properties of a DR5 receptor-selective mutant variant of the antitumor cytokine TRAIL DR5-B in human pancreatic cancer cell lines, after prolonged co-incubation with gemcitabine or doxorubicin. In the MIA PaCa-2 and PANC-1 cell lines, both drugs significantly increased β-galactosidase activity and the expression of senescence markers, such as the cell cycle inhibitors p21 and p27; DR5-B effectively suppressed cell viability after chemotherapy treatment. In the BxPC-3 cell line, the drugs did not induce senescence and DR5-B cytotoxicity was virtually unchanged. Some features of senescence were observed in AsPC-1 cells; however, these cells remained resistant to DR5-B, presumably due to cFLIP overexpression. Hence, the DR5-B protein shows promise as a senolytic agent for the treatment of certain types of pancreatic adenocarcinoma.