RP1 Monotherapy Trial Data for Skin Cancer in Transplant Recipients at AACR 2024

Replimune Group, Inc., a clinical-stage biotechnology firm, has reported promising interim results from its Phase 1/2 clinical trial, ARTACUS. The trial is assessing the efficacy of RP1 monotherapy, a novel oncolytic immunotherapy, in treating skin cancers among patients who have undergone solid organ or hematopoietic cell transplants. The findings, presented by Michael R. Midgen, M.D., at the AACR 2024 Annual Meeting, indicate a significant overall response rate of 34.8 percent among the 23 evaluable participants.

RP1 monotherapy was administered up to 25 times, leading to five complete and three partial responses. Notably, a patient with cutaneous squamous cell carcinoma (CSCC) experienced a complete response to a new primary basal cell carcinoma that emerged post-baseline. The treatment was well-tolerated, with a safety profile comparable to that of non-immunocompromised patients with advanced skin cancers. Furthermore, biomarker data revealed an increase in CD+8 T cells and PD-L1 expression post-treatment, suggesting an activation of the immune system.

Sushil Patel, Ph.D., CEO of Replimune, highlighted the importance of these results, as organ transplant recipients face a higher risk of skin cancer and have limited treatment options due to the contraindication of systemic immunotherapy. The nearly 35 percent overall response rate observed with RP1 monotherapy offers a potentially safe and effective alternative for this patient group.

The ARTACUS study is an open-label, two-part Phase 1b/2 trial that is still enrolling participants. It is designed to evaluate the safety and tumor-shrinking capabilities of RP1 monotherapy in patients with locally advanced or metastatic cutaneous malignancies who have received various types of transplants and are on chronic immunosuppressive treatment.

RP1, Replimune's leading product candidate, is based on a proprietary strain of herpes simplex virus. It has been engineered to include a fusogenic protein and GM-CSF to enhance its tumor-killing potency and to stimulate a systemic anti-tumor immune response. Replimune, founded in 2015, is dedicated to revolutionizing cancer treatment through the development of its oncolytic immunotherapy portfolio.

The company's RPx platform is built on a potent HSV-1 backbone, aiming to maximize immunogenic cell death and induce a systemic anti-tumor immune response. The platform is unique in its dual local and systemic activity, which includes direct virus-mediated tumor killing and the alteration of the tumor microenvironment to trigger a robust and durable systemic response. The RPx product candidates are anticipated to be synergistic with a wide range of established and experimental cancer treatments, offering flexibility for standalone or combination therapy development.

Replimune is headquartered in Woburn, MA, and is committed to pioneering innovative approaches to cancer treatment.