KLS-3021: a Promising Oncolytic Virus for Prostate Cancer

KLS-3021 is a novel oncolytic virus therapy developed for the treatment of prostate cancer. It employs a recombinant vaccinia virus engineered to selectively infect and destroy cancer cells while activating the immune system to target tumors more effectively. The virus carries three therapeutic genes: PH-20, which degrades the extracellular matrix to facilitate viral spread and immune cell infiltration; IL-12, a cytokine that stimulates strong anti-tumor immune responses; and sPD1-Fc, which inhibits immune checkpoint pathways that cancer cells use to evade detection.

Preclinical studies have demonstrated that a single intratumoral administration of KLS-3021 significantly reduced tumor size in prostate cancer models, outperforming the chemotherapy drug docetaxel. This efficacy was evident not only in tumors confined to the prostate but also in locally invasive tumors with lymph node metastases, suggesting potential use for both localized and metastatic disease. Tissue analyses confirmed widespread viral distribution within tumors, breakdown of the tumor’s physical barriers, increased infiltration of immune-activating cells, and induction of immunogenic cell death, which collectively support sustained anti-cancer immune activity.

This therapy offers a minimally invasive treatment option delivered directly into the tumor under imaging guidance, making it particularly suitable for prostate cancer patients with low-grade disease or those on active surveillance. Additionally, it holds promise as a neoadjuvant therapy to shrink tumors before surgical or radiation intervention, potentially improving outcomes and reducing the extent of traditional treatments.

Having completed necessary preclinical safety and efficacy studies, KLS-3021 is moving toward phase 1 clinical trials designed to evaluate safety and early effectiveness in humans.

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