Why Immunotherapy Fails in HGSC Models

BUFFALO, NY - September 24, 2025 – A new #research paper was #published in Volume 16 of Oncotarget on September 22, 2025, titled “Loss of Trp53 results in a hypoactive T cell phenotype accompanied by reduced pro-inflammatory signaling in a syngeneic orthotopic mouse model of ovarian high-grade serous carcinoma.” In this study, led by first author Jacob Haagsma and corresponding author Trevor G. Shepherd from the Verspeeten Family Cancer Centre and Western University, Canada, researchers investigated how the loss of Trp53 – a critical tumor suppressor gene – affects immune responses in ovarian cancer. The team found that deleting Trp53 led to more aggressive tumor growth and a weaker immune response. These findings help explain why some ovarian tumors may be resistant to immunotherapy and point to new ways to improve treatment. High-grade serous ovarian carcinoma (HGSC) is a deadly cancer that is often diagnosed at a late stage. Immunotherapy, which enhances the body’s immune system to fight cancer, has shown limited effectiveness in treating this type of cancer. To better understand why, the researchers developed a mouse model that closely mimics human HGSC. They injected ovarian epithelial cells, with and without Trp53, into the fallopian tubes, the origin site of most ovarian cancers. “In this study, we developed a syngeneic model reflecting both the site of origin and the genotype of early HGSC disease by deleting Trp53 in mouse oviductal epithelial (OVE) cells.” Mice injected with cells lacking Trp53 developed faster-growing and more invasive tumors, reflecting how the disease typically progresses in humans. These tumors also had fewer active T cells, which are immune cells responsible for attacking cancer. Moreover, the T cells that were present appeared less capable of responding to the tumor, creating an immune environment that allowed cancer to grow uncontrolled. Further analysis revealed that tumor cells without Trp53 had reduced activity in genes related to inflammation. These changes were associated with lower levels of key proteins that normally help immune cells detect and attack tumor cells. When the researchers collected tumor cells from the abdominal fluid of the mice—a condition that simulates advanced-stage disease—they observed even lower immune signaling than before. This suggests that as the tumor spreads, it becomes better at evading the immune system. This study highlights how early genetic mutations can shape the interaction between tumors and the immune system. In particular, the loss of Trp53 appears to trigger a chain of events that weakens immune surveillance and accelerates tumor progression. These findings emphasize the need to consider both genetic mutations and the tumor environment when designing immunotherapies for ovarian cancer. Understanding how genes like Trp53 influence immune behavior may lead to more effective treatments and help identify which patients are most likely to benefit from immunotherapy. DOI - https://doi.org/10.18632/oncotarget.28768 Correspondence to - Trevor G. Shepherd - tshephe6@uwo.ca Abstract video - https://www.youtube.com/watch?v=WFQw0psuC3M Sign up for free Altmetric alerts about this article - https://oncotarget.altmetric.com/details/email_updates?id=10.18632%2Foncotarget.28768 Subscribe for free publication alerts from Oncotarget - https://www.oncotarget.com/subscribe/ To learn more about Oncotarget, please visit https://www.oncotarget.com and connect with us: Facebook - https://www.facebook.com/Oncotarget/ X - https://twitter.com/oncotarget Instagram - https://www.instagram.com/oncotargetjrnl/ YouTube - https://www.youtube.com/@OncotargetJournal LinkedIn - https://www.linkedin.com/company/oncotarget Pinterest - https://www.pinterest.com/oncotarget/ Reddit - https://www.reddit.com/user/Oncotarget/ Spotify - https://open.spotify.com/show/0gRwT6BqYWJzxzmjPJwtVh MEDIA@IMPACTJOURNALS.COM