Bone and Soft-Tissue Sarcoma: A New Target for Telomerase-Specific Oncolytic Virotherapy

Area of Science:

• Oncolytic virotherapy
• Cancer gene therapy
• Adenovirus vector technology

Background:

• Adenovirus serotype 5 (Ad5) is a common vector in cancer gene therapy and oncolytic virotherapy.
• Oncolytic virotherapy aims to induce tumor cell death while sparing normal cells.
• Telomerase is a key enzyme often overexpressed in cancer cells.

Purpose of the Study:

• To review the therapeutic potential of three novel oncolytic adenoviruses (OBP-301, OBP-401, OBP-702) targeting telomerase activity in bone and soft-tissue sarcomas.
• To highlight the distinct mechanisms and applications of each engineered adenovirus.

Main Methods:

• Development of replication-competent oncolytic adenoviruses (OBP-301, OBP-401, OBP-702) based on the Ad5 genome.
• Engineering viruses to express adenoviral E1A and E1B genes under the human telomerase reverse transcriptase (hTERT) promoter for tumor-specific replication.
• Evaluation of OBP-301, OBP-401, and OBP-702 for their antitumor effects, imaging capabilities, and mechanisms of action in sarcoma models.

Main Results:

• OBP-301 (Telomelysin) demonstrated antitumor effects through autophagy and apoptosis induction, effective in monotherapy and combination treatments.
• OBP-401 (TelomeScan) facilitates visualization of sarcoma cells using GFP expression for fluorescence-guided surgery.
• OBP-702 showed significant antitumor activity in OBP-301-resistant cells by activating the p53 signaling pathway.

Conclusions:

• hTERT promoter-driven oncolytic adenoviruses represent promising therapeutic agents for bone and soft-tissue sarcomas.
• These viruses offer novel treatment strategies, including direct tumor cell killing, diagnostic imaging, and overcoming therapeutic resistance.
• The distinct functionalities of OBP-301, OBP-401, and OBP-702 provide versatile options for sarcoma management.