Banner MD Anderson study finds breakthrough potential in melanoma treatment
New trial therapy shrinks tumors in a third of patients with resistant melanoma
8/1/2025
A new study at Banner MD Anderson Cancer Center offers new hope for patients with advanced melanoma who no longer respond to standard immunotherapies.
In a Phase II clinical trial, researchers found that a novel investigational treatment — RP1, a genetically engineered virus — used in combination with the immunotherapy drug nivolumab significantly shrank tumors in about one in three patients whose disease had progressed after standard treatment.
The trial enrolled 140 patients with advanced melanoma resistant to anti-PD-1 therapy, a common first-line immunotherapy. Historically, these patients have very few effective treatment options and face a median overall survival of just one year.
Notably, 15% of participants experienced a complete response, with all signs of cancer disappearing. Among those who responded, more than half remained in remission two years later.
This research and care is under the auspices of the T.W. Lewis Melanoma Center of Excellence at Banner MD Anderson, dedicated to the prevention and treatment of melanoma – with a mission is to provide quality care and become the leading melanoma center in the Southwest. The Center was established in 2017 thanks to a generous matching gift from Tom and Jan Lewis through The TW Lewis Foundation. Tom Lewis, who lost his father to melanoma, is a melanoma survivor himself. Since opening, the Center has treated over 3,800 new patients and continues to grow.
“These are clinically meaningful results, especially when you consider the limited alternatives for patients once common therapy stops working,” said principal investigator Jiaxin Niu, MD, Ph.D. He is also the co-director of the lung cancer program at Banner MD Anderson.
The study also found that RP1 could shrink tumors that were not directly injected, including in organs like the liver and lungs—suggesting a systemic immune response. Patients responded regardless of tumor size, location, or specific genetic traits like BRAF mutations.
Importantly, the combination was well tolerated. While most patients experienced mild side effects such as fatigue or fever, only 12.9% had serious treatment-related side effects. No treatment-related deaths occurred. RP1 is a modified herpes simplex virus that has been engineered to target and destroy cancer cells while stimulating a broader immune response. It delivers immune-activating proteins, which enhance tumor cell destruction and immune system engagement.
Biomarker analyses from the study revealed increases in immune activity in the tumor in patients who responded to treatment, helping researchers better understand the therapy’s mechanism of action and laying the groundwork for future research.
While the trial was not randomized and did not include a control group, the results compare favorably to historical outcomes.
“The durability of the response is particularly encouraging, and we are hopeful that these results will support FDA approval,” said Dr. Niu. “I am deeply grateful to our courageous patients and their families, as well as to my dedicated colleagues and supportive staff. Their strength and commitment made this option possible for other patients in the near future.”
“This is a significant new option for patients with melanoma. In the broader context, it also marks an important step toward establishing our center as a leading hub for oncology research in the Southwest,” said Matthew Callister, MD, senior physician executive for Banner MD Anderson.