A protein that helps cancer cells control oxidative stress may explain why some blood cancers eventually stop responding to BTK inhibitors, a widely used class of targeted drugs. Researchers at Weill Cornell Medicine report that the protein, known as BRG1, protects mantle cell lymphoma cells by blocking ferroptosis, an iron-dependent form of cell death. Their findings suggest that inhibiting BRG1 could restore the effectiveness of BTK inhibitors in tumors that have become resistant to treatment.
BTK inhibitors work by suppressing Bruton’s tyrosine kinase, an enzyme that transmits signals essential for the growth, survival and activation of B cells. Because mantle cell lymphoma and several other B-cell malignancies depend heavily on these signaling pathways, drugs that inhibit BTK can produce powerful clinical responses. Yet the benefit is often temporary. Many patients relapse after one or two years as lymphoma cells acquire or select for biological changes that allow them to survive despite continued treatment.
The new study, published in Nature Communications, identifies an unexpected mechanism behind this resistance. In mantle cell lymphoma cells that remain sensitive to BTK inhibitors, treatment triggers ferroptosis rather than simply starving the cells of growth signals. Ferroptosis is a distinct form of regulated cell death driven by the uncontrolled oxidation of lipids, the fatty molecules that form cellular membranes. As oxidized lipids accumulate, the membrane loses its integrity and eventually ruptures, killing the cell.
This process depends on the presence of both reactive oxygen species and available iron. Iron can catalyze chemical reactions that convert relatively stable oxygen-containing molecules into highly reactive compounds. These reactions initiate a chain reaction in membrane lipids, producing toxic lipid peroxides. Healthy cells normally prevent this damage through antioxidant systems, but rapidly dividing cancer cells operate under substantial metabolic stress and can become especially vulnerable when those defenses are disrupted.
Dr. Soo-Yeon Hwang, a postdoctoral associate in the laboratory of Dr. Jihye Paik at Weill Cornell Medicine, and colleagues compared lymphoma cells obtained from patients who responded to BTK inhibitors with cells from patients whose cancers had become resistant. The distinction was striking. BTK treatment induced the molecular and biochemical features of ferroptosis in sensitive cells, while resistant cells avoided the same fate. The researchers traced this difference to abnormal activity of BRG1, a protein that regulates how DNA is packaged and read.
BRG1 is a chromatin remodeler, meaning that it helps rearrange the structure of chromatin—the complex of DNA and proteins inside the nucleus. By repositioning nucleosomes, the compact units around which DNA is wrapped, chromatin remodelers can make particular genes more or less accessible to the transcriptional machinery. This gives them broad influence over cellular behavior. In mantle cell lymphoma, BRG1 is frequently mutated or otherwise dysregulated in tumors that no longer respond to BTK inhibitors.
The researchers found that aberrant BRG1 rewires gene expression in a way that suppresses ferroptosis. Its activity reduces the cellular conditions required for the death process, including the accumulation of reactive oxygen and free iron. In effect, BRG1 acts as a protective shield: while BTK inhibition places the lymphoma cell under stress, BRG1 strengthens the cell’s ability to neutralize oxidative damage before it can spread through the membrane.
This finding helps explain why simply continuing BTK inhibitor treatment may fail even when the drug remains capable of blocking its original molecular target. Resistance does not necessarily arise because the lymphoma cell restores BTK signaling. Instead, the cell can bypass the lethal consequences of BTK inhibition by changing its metabolism and antioxidant defenses. BRG1 therefore represents a vulnerability downstream of the drug’s primary target, one that may be exploitable even after the cancer has stopped responding to BTK therapy.
In laboratory experiments and animal models, combining a BRG1 inhibitor with a BTK inhibitor substantially increased antitumor activity compared with BTK inhibition alone. The combination also extended survival in treated animals. These results provide early evidence for a therapeutic strategy in which the cancer’s antioxidant protection is dismantled while BTK signaling is simultaneously suppressed. The approach could potentially be relevant beyond mantle cell lymphoma, although its safety and effectiveness in people will require clinical testing.
The study also highlights the growing importance of ferroptosis in cancer biology. Unlike apoptosis, the best-known form of programmed cell death, ferroptosis is governed by iron handling, lipid metabolism and cellular redox balance. Because malignant cells frequently divide rapidly and remodel their membranes at high rates, they may carry a biochemical weakness that can be exposed by targeted therapies. The Weill Cornell findings suggest that understanding which tumors retain or suppress this weakness could help guide treatment decisions and reveal combination therapies for patients whose cancers have become resistant.
Web References: https://www.nature.com/articles/s41467-026-75123-4
References: Nature Communications study published 2 July 2026; Weill Cornell Medicine investigators Dr. Soo-Yeon Hwang, Dr. Jihye Paik and Dr. Hongwu Zheng.
Keywords: Mantle cell lymphoma, BTK inhibitors, Bruton’s tyrosine kinase, BRG1, ferroptosis, oxidative stress, cancer drug resistance, B lymphocytes, chromatin remodeling, targeted therapy
