We believe there are several important advantages of PVSRIPO as an immunotherapy for cancer treatment:
- The poliovirus receptor CD155 is expressed in virtually all solid cancers, as well as dendritic cells, macrophages and other immune cells.
- PVSRIPO infects and kills tumor cells that express CD155.
- PVSRIPO infection of immune cells facilitates induction of an antitumor immune response.
- PVSRIPO is the only oncolytic virus that is not destroyed by the Type 1 interferon response caused by these viruses.
- Other oncolytic viruses kill or limit dendritic cells. PVSRIPO stimulates dendritic cell activity and immune function.
- Cancer patients who are immune to polio and have been boosted with the Salk vaccine experience a recall immune response upon intratumoral PVSRIPO infusion.
For targeting glioblastoma, the vaccine is delivered by direct intratumoral delivery via convection-enhanced delivery (CED), which by-passes the blood-brain barrier and reduces systemic toxicity. CED is commonly used, and we believe it is reproducible in multiple centers. Less than 5% of the tumor volume needs to be injected to achieve high drug concentrations throughout the tumor. BrainLAB and Therataxis software allow highly accurate and reproducible drug distribution and injection accuracy.
The FDA granted PVSRIPO Breakthrough Therapy Designation on May 10, 2016. Breakthrough Therapy Designation conveys all fast track program features, more intensive FDA guidance on an efficient drug development program, an organizational commitment involving senior FDA managers, and eligibility for rolling review and priority review.
The FDA also granted PVSRIPO Orphan Drug designation for glioblastoma on May 26, 2016. Benefits of this designation include tax credits of 50% of the clinical drug testing cost awarded upon approval, waiver of NDA/BLA application fee, and seven years of data exclusivity upon approval (that is, it bars the FDA from approving any other application for the same drug for the same orphan disease or condition for seven years).