5NT Targets FOXM1 in Triple-Negative Breast Cancer

Key Takeaways

• In analyzed human breast cancer datasets, FOXM1 expression was reported as higher in tumor and metastatic tissue than in normal breast tissue, and higher FOXM1 was associated with poorer overall and relapse-free survival in the studied breast cancer cohort.
• The investigators reported that FOXM1 expression was higher in TP53-mutant than TP53-wild-type breast cancers, and FOXM1 expression fell after p53 knockdown in mutant-p53 MDA-MB-231 and MDA-MB-436 triple-negative breast cancer cells.
• In explicitly preclinical triple-negative breast cancer models, 5NT downregulated FOXM1, showed Bliss-model synergy with doxorubicin in MDA-MB-231 cells (11.504), and reduced orthotopic xenograft growth with no reported differences in body weight or serum chemistry readouts.

FOXM1 tracked with poorer-outcome breast cancer biology and then became the target of a preclinical triple-negative breast cancer intervention program that tested liposomal 5NT at 50 mg/kg in mice. The authors paired human expression and survival analyses with mechanistic cell-model experiments and orthotopic xenografts, linking higher FOXM1 to TP53-associated disease biology before asking whether pharmacologic FOXM1 suppression could alter proliferation, motility, and chemotherapy sensitivity in nonclinical models.

In the FOXM1-targeted preclinical TNBC study, investigators combined human dataset analyses with mechanistic TNBC cell-line work, docking, combination testing, and orthotopic xenografts. In a survival cohort of 1,879 patients, including a high-FOXM1 group of 1,311, higher FOXM1 expression was associated with poorer overall and relapse-free survival; in a TP53-stratified dataset, FOXM1 was higher in TP53-mutant than TP53-wild-type breast cancers (n=93 vs n=124). FOXM1 overexpression increased colony formation, migration, and invasion, whereas FOXM1 siRNA at 100 nmol/L reduced those phenotypes across the tested TNBC models, and the human dataset findings were associative rather than causal.

5NT was the study's experimental FOXM1-directed intervention. Docking predicted interaction in the FOXM1 DNA-binding domain at a calculated binding ability of -4.9 kcal/mol and highlighted residues including Arg286 and His287. In MDA-MB-231 and MDA-MB-436 cells, 5NT reduced FOXM1 expression at 1 micromolar and higher, while also suppressing clonogenic growth, reducing migration and invasion, and inducing apoptosis. For orientation, the comparator FDI-6 had a reported approximate IC50 of 10 micromolar in both cell lines.

In combination testing, investigators reported Bliss Independence scores for 5NT plus doxorubicin of 11.504 in MDA-MB-231 cells and 1.814 in MDA-MB-436 cells. In the orthotopic MDA-MB-231 xenograft model, 2 x 10^6 cells were implanted and treatment began after 7 days when tumors reached 3 to 5 mm; mice were assigned at n=5 per group and received liposomal 5NT at 50 mg/kg three times weekly for 4 weeks, after which the study reported reduced tumor growth. No reported body-weight change and no significant differences in ALT, AST, BUN, creatinine, or LDH were observed, and the authors added that more stringent toxicology studies would be needed before Phase I testing.

Clinician Questions

How was FOXM1 linked to TP53-mutant triple-negative breast cancer in this analysis?

FOXM1 expression was reported as higher in TP53-mutant than TP53-wild-type breast cancers in the analyzed datasets, with subgroup sizes of 93 versus 124, and p53 knockdown reduced FOXM1 expression in mutant-p53 MDA-MB-231 and MDA-MB-436 cells.

What did 5NT do in triple-negative breast cancer cell models targeting FOXM1?

In the triple-negative breast cancer cell models tested, 5NT was predicted by docking to interact at the FOXM1 DNA-binding domain, reduced FOXM1 expression at 1 micromolar and higher in MDA-MB-231 and MDA-MB-436 cells, inhibited colony formation, reduced migration and invasion, and induced apoptosis.

Did 5NT show synergy with doxorubicin in triple-negative breast cancer models?

The investigators reported Bliss Independence synergy scores of 11.504 in MDA-MB-231 cells and 1.814 in MDA-MB-436 cells for 5NT plus doxorubicin, and this was a cell-line combination analysis rather than a clinical treatment result.

What were the mouse xenograft findings for liposomal 5NT in MDA-MB-231 tumors?

In an orthotopic MDA-MB-231 xenograft model, mice received liposomal 5NT at 50 mg/kg three times weekly for 4 weeks starting 7 days after implantation when tumors were 3 to 5 mm, with n=5 per group, and the study reported reduced tumor growth without reported differences in body weight or serum ALT, AST, BUN, creatinine, or LDH.