RP4

RP4 is a discovery-stage oncolytic immunotherapy being developed by Replimune Group. It is built upon the company's proprietary Immulytic platform, which utilizes a hyper-potent, clinical-grade strain of Herpes Simplex Virus type 1 (HSV-1) engineered to selectively replicate within tumor cells. This selective replication leads to immunogenic cell death and the release of tumor-associated antigens, thereby stimulating a systemic anti-tumor immune response. Like other candidates in the Replimune pipeline (such as RP1, RP2, and RP3), RP4 is designed to express therapeutic payloads directly within the tumor microenvironment. Early development reports indicated that RP4 was intended to express Interleukin-12 (IL-12) to further enhance Th1-type immune responses and activate natural killer (NK) cells, although the program has remained in the discovery phase while the company prioritizes its more advanced clinical candidates.