Targeting a Cleft in Retinoblastoma Protein Offers New Hope for Cancer Treatment

Researchers at the Wistar Institute have made a groundbreaking discovery that could potentially lead to a new therapeutic target for ovarian and other cancers. By targeting a specific cleft in the retinoblastoma protein, scientists were able to kill tumor-protecting macrophages, making the tumor cells more vulnerable to immune attack. This approach offers a novel therapeutic target that could potentially make cancer more sensitive to immunotherapies.

Key Takeaways:

• The retinoblastoma protein, long thought to suppress cancer cells, was found to have a cleft that, when targeted, could turn off its ability to protect tumor-supporting macrophages without affecting its cancer-suppressing abilities.
• Macrophages are immune cells that have different functions in the body, and tumor cells use them to create a protective environment that shields them from immune attack.
• Researchers found that blocking the cleft in the retinoblastoma protein turned off its ability to protect tumor-supporting macrophages, depleting the population of these cells and making the tumor cells vulnerable to immune attack.
• This approach was tested in animals, and tumors shrank as a result of the treatment.
• The study points to the importance of interdisciplinary research, as discoveries in one area of medicine, such as HIV, can lead to breakthroughs in other fields, such as cancer.
• The team is working on follow-up research, including studying how regulating retinoblastoma protein affects macrophages in acute myeloid leukemia and pancreatic cancer, as well as testing the approach in combination with immunotherapy.

Statistics:

• More than 10 years of research were required to link retinoblastoma with macrophage survival and to the publication of their findings supporting this new approach to treat cancer.
• 10 research years were spent working on behalf of The Wistar Institute.
• The study highlights the importance of taking an interdisciplinary approach to research, as discoveries in one area of medicine can have far-reaching implications in other fields.
• The team is working with other researchers to further develop this new approach to cancer treatment.
• NIH grant R01CA1665065 ($X) supported the research.
• Work was also supported by the Department of Defense grant W81XWH-19-1-0092, and PA Department of Health CURE funds.

Sources:

• "Targeting LxCxE cleft pocket of retinoblastoma protein in M2-like immunosuppressive macrophages inhibits ovarian cancer progression," Cancer Immunotherapy Research, 2025 (online publication).
• The Wistar Institute.
• COMTEX_468656589/2010/2025-09-09T10:15:00