Researchers at University of Texas MD Anderson Cancer Center and Weill Cornell Medicine have identified key mechanisms that allow colorectal tumors to resist KRAS inhibitors, uncovering both genetic and non-genetic pathways that help cancer cells survive treatment.
The findings, published in Cancer Cell, suggest that combining KRAS inhibitors with therapies targeting early inflammatory responses may improve outcomes for patients with KRAS-mutant colorectal cancer.
KRAS mutations remain difficult to treat in colorectal cancer
KRAS is one of the most commonly mutated oncogenes in colorectal cancer, occurring in nearly half of all patients. Mutations in the gene drive tumor growth by continuously activating signaling pathways involved in cell proliferation and survival.
Although KRAS inhibitors such as Adagrasib and Sotorasib have transformed treatment options for some lung cancers, their clinical benefit in colorectal cancer has been more limited. Many patients either fail to respond or rapidly develop resistance after an initial response.
Previous studies have suggested that tumors may escape treatment by acquiring secondary pathway mutations, but the full picture of resistance has remained unclear.
To investigate this further, the research team analyzed patient-matched tumor samples collected before treatment, during KRAS inhibitor therapy, and after disease progression. The researchers combined targeted gene sequencing with single-cell spatial transcriptomics to examine how tumor cells evolved over time.
The team also used organoid models of KRAS inhibitor-resistant colorectal cancer to validate their findings experimentally.
Tumors evade KRAS inhibition through multiple mechanisms
The researchers discovered that resistant tumors do not rely on a single escape mechanism. Instead, colorectal cancer cells use both genetic mutations and adaptive cell-state changes to survive therapy.
Some resistant cancer cells acquired secondary mutations that bypassed KRAS blockade, while others altered their cellular behavior without acquiring new mutations. According to the authors, these non-genetic adaptations enabled tumor cells to tolerate treatment and remain viable despite continued KRAS inhibition.
Both resistance mechanisms could coexist within the same tumor, highlighting the complexity and heterogeneity of treatment resistance in colorectal cancer.
“Our findings uncovered the genetic and cell-state shifts that colorectal tumors use to escape KRAS inhibition,” said co-lead author Salvador Alonso Martinez, MD, assistant professor of Gastrointestinal Medical Oncology at MD Anderson.
“Targeting the adapted early inflammatory response may be the key to stopping resistance and improving the effectiveness of KRAS therapies for these patients,” he added.
Early inflammatory signaling helps cancer cells survive
One of the study’s most significant findings was the identification of an early inflammatory response triggered shortly after KRAS inhibitor treatment begins.
In tumor samples collected early during therapy, the researchers observed activation of inflammation-related signaling programs that appeared to help cancer cells adapt to therapeutic stress.
Rather than immediately dying in response to KRAS blockade, some tumor cells entered a survival state driven by inflammatory signaling pathways. This adaptive response allowed them to persist and eventually contribute to disease progression.
The investigators identified the protein kinase TBK1 as a central mediator of this inflammatory adaptation.
TBK1 is known to regulate innate immune and inflammatory signaling pathways, but the new findings suggest it may also play a critical role in enabling colorectal tumors to survive KRAS inhibition.
When the researchers blocked TBK1 activity in preclinical models, the inflammatory survival response was suppressed and tumor cells became more sensitive to KRAS inhibitors.
Combination therapy may improve treatment durability
The results suggest that combining KRAS inhibitors with TBK1 blockade could represent a new therapeutic strategy for patients with KRAS-mutant colorectal cancer.
Rather than focusing exclusively on secondary genetic mutations after resistance has already emerged, targeting the early adaptive inflammatory response may help prevent or delay resistance from developing in the first place.
In preclinical organoid models, dual inhibition strategies enhanced treatment sensitivity and overcame resistance mechanisms that limited the effectiveness of KRAS inhibition alone.
The study’s authors believe this approach could potentially produce more durable responses in patients, though clinical validation will still be required.
Implications for future colorectal cancer treatment
The findings add to growing evidence that cancer drug resistance is often driven not only by permanent genetic evolution, but also by reversible adaptive cell states that emerge under therapeutic pressure.
Understanding these early adaptive mechanisms may help researchers design combination therapies that suppress tumor survival pathways before resistant clones become dominant.
The study also demonstrates the increasing importance of single-cell and spatial transcriptomic technologies in oncology research, allowing scientists to observe how tumors dynamically respond to treatment at high resolution.
While TBK1 inhibitors are not yet standard therapies for colorectal cancer, the researchers believe their work provides a strong rationale for future clinical trials combining TBK1 blockade with KRAS-targeted therapies.
If successful, these strategies could expand the clinical impact of KRAS inhibitors in colorectal cancer, where durable responses have historically been difficult to achieve.
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