Philadelphia researchers have identified a previously overlooked way ovarian tumors may make chemotherapy less effective: by turning the body’s own inflammatory response into a protective shield. The Wistar Institute-led study traces that defense to IL-1β, neutrophils and web-like structures that help tumors survive the next round of treatment.
The study was published June 3 in the Journal for ImmunoTherapy of Cancer, and Wistar’s release brought the findings fresh local attention last Thursday. Researchers from Wistar, the University of Pennsylvania and Kyoto University Graduate School of Medicine collaborated on the work.
How Chemotherapy May Rally The Tumor’s Defenses
High-grade serous carcinoma is the most common histologic subtype of ovarian cancer, and the National Cancer Institute notes that it often spreads early and is diagnosed at an advanced stage, making treatment resistance especially dangerous. Many patients initially respond to chemotherapy, but recurrent disease can become resistant to later treatment.
Using paired patient tumor samples, mouse models and laboratory experiments, researchers found that chemotherapy increased IL-1β, an inflammatory signal, in the tumor environment. The signal appeared to act through receptors on tumor-associated fibroblasts, which increased CXCL2 and recruited neutrophils; those neutrophils then formed neutrophil extracellular traps, or NETs, that reduced chemotherapy effectiveness in lab tests. Mice unable to produce or respond to IL-1β developed tumors that responded better to chemotherapy, while post-treatment human tumor samples showed more neutrophil infiltration and a trend toward increased NET formation, according to the research paper.
The discovery pushes back on the idea that chemotherapy resistance is only a problem inside cancer cells. Nan Zhang, the study’s senior author, said the findings suggest resistance is “also an immunology problem, not only a cancer-cell problem,” while Wistar noted that some drugs targeting the IL-1β pathway are already approved for other diseases.
Promising Pathway Still Needs Clinical Testing
That distinction matters because treatment choices after ovarian cancer returns are still organized around how quickly the disease comes back and whether it remains platinum-sensitive. The 2026 ASCO living guideline outlines different systemic options for platinum-sensitive and platinum-resistant recurrence, but this Wistar finding does not yet establish a new patient treatment.
The researchers still do not know what specifically triggers the post-chemotherapy surge in IL-1β or exactly how NETs blunt drug sensitivity. The team is now exploring whether interrupting the IL-1β-neutrophil pathway, potentially alongside immune checkpoint inhibitors, can move the Philadelphia discovery from a promising mechanism toward a clinical strategy, the study reports.
