Longitudinal tracking of MALAT1 level over a breast cancer patient's course of treatment and disease progression.

Long non-coding RNAs (lncRNAs) have emerged as important regulators of the hallmarks of cancer, yet their potential remains under-explored in clinical studies. Metastasis-Associated Lung Adenocarcinoma Transcript 1 (MALAT1), an lncRNA upregulated in over 20 tumor types including breast tumors, has been associated with metastasis, yet its expression across the clinical course of treatment and disease progression remains uncharacterized. For the first time, this case report evaluated MALAT1 level in multiple biopsies collected over a breast cancer patient's clinical course of treatment spanning 2.5 years, using quantitative single-molecule RNA fluorescence in situ hybridization. We observed that MALAT1 levels were consistently elevated in tumor cells relative to adjacent stroma, reduced upon standard-of-care therapeutic interventions, and markedly increased in distant metastatic lesions. These longitudinal changes in expression level demonstrate a link between MALAT1 and disease progression. Our findings highlight the potential of MALAT1 as a prognostic marker for treatment response and metastatic risk stratification and support pursuing MALAT1 as a therapeutic target.