Researchers identify an IL-1β-driven inflammatory loop behind bone damage and disease progression in TCF3::HLF-positive B-ALL

A rare and aggressive form of childhood leukemia, TCF3::HLF-positive B cell acute lymphoblastic leukemia (B-ALL), has been linked to an inflammatory mechanism that drives both disease progression and bone destruction, according to new research published in Blood.

The study addresses a longstanding gap in understanding why patients with this subtype experience severe bone damage alongside rapid cancer growth and poor survival outcomes. Progress in the field has been limited in part by the lack of disease models that accurately reflect human biology.

Researchers at Tokyo University of Science and collaborators developed a mouse model by engineering precursor blood cells to express the TCF3::HLF fusion gene, which defines this leukemia subtype. The resulting disease closely mirrored the clinical features seen in patients, including abnormal blood cell expansion and bone loss.

Using this model, the team identified high levels of interleukin-1 beta (IL-1β), an inflammatory signalling protein, produced directly by leukemia cells. This differs from other forms of leukemia, where IL-1β is typically generated by immune cells.

Further experiments showed that IL-1β acts as both a growth signal for leukemia cells and a driver of bone damage. The protein promotes cancer cell proliferation while activating osteoclasts through RANKL signalling, leading to bone degradation.

The study also identified how this process is initiated. The TCF3::HLF fusion protein functions as an abnormal transcription factor that directly activates IL-1β through a previously uncharacterised genomic region, creating a feedback loop between inflammation and tumour growth.

Tomokatsu Ikawa, professor at Tokyo University of Science, said: “Our findings delineate a self-reinforcing loop in which TCF3::HLF directly induces IL-1β transcription, thereby driving both leukemic expansion and bone destruction.”

The researchers tested whether disrupting this pathway could affect disease progression. In the mouse model, blocking IL-1β reduced leukemia growth, limited bone damage and improved survival. Combining IL-1β inhibition with an existing leukemia treatment further enhanced these effects.

Ikawa added: “This work highlights inflammatory signaling as a promising therapeutic target in this otherwise incurable leukemia subtype.”

The findings also suggest broader relevance, as IL-1β activity has been observed in other blood cancers, including acute myeloid leukemia and multiple myeloma.

While the results are based on preclinical data, the study provides a clearer explanation for the aggressive nature of TCF3::HLF-positive B-ALL and identifies a potential therapeutic target. Further research will be needed to determine whether these findings translate into clinical benefit, with early-phase studies expected in the coming years.