Design, development, and evaluation of gene therapeutics specific to KSHV-associated diseases

Area of Science:

• Oncology
• Virology
• Gene Therapy

Background:

• Kaposi sarcoma-associated herpesvirus (KSHV) causes Kaposi sarcoma and B cell lymphoproliferative diseases.
• KSHV-encoded latency-associated nuclear antigen (LANA) is crucial for viral genome maintenance and is expressed in KSHV-infected cancer cells, making it a therapeutic target.

Purpose of the Study:

• To develop a cancer gene therapy vector using adeno-associated virus (AAV) that specifically targets KSHV-infected cells.
• To exploit KSHV's latency-associated nuclear antigen (LANA) and terminal repeat (TR) functions for targeted gene expression and cancer cell eradication.

Main Methods:

• Engineered an AAV vector (AAV8-TR2-OriP-TK) incorporating KSHV terminal repeats (TR) and a lytic inducible promoter to express thymidine kinase (TK) selectively in KSHV-infected cells.
• Administered AAV8-TR2-OriP-TK followed by ganciclovir (GCV) to KSHV-infected cells and a xenograft tumor model.
• Investigated the synergistic effect of AAV8-TR2-OriP-TK/GCV with anti-cancer drugs known to reactivate KSHV.

Main Results:

• AAV8-TR2-OriP-TK/GCV effectively eradicated KSHV-infected cells, including stem cell-derived epithelial cells, without harming non-infected cells.
• The vector suppressed KSHV virion production from reactivated cells and synergized with anti-cancer drugs to enhance therapeutic efficacy.
• The treatment suppressed KSHV-infected tumor growth in a xenograft model with no detectable side effects from systemic AAV administration.

Conclusions:

• AAV-mediated gene therapy targeting KSHV offers a promising strategy for treating KSHV-driven cancers.
• The developed vector system demonstrates selective cancer cell killing and viral replication inhibition.
• This approach holds potential for future therapeutic interventions against herpesvirus-associated malignancies.