Metabolomic Profiling Identifies Serum N1-Acetylspermidine As a Tumor-Specific Prognostic Biomarker for T-Lymphoblastic Lymphoma/Acute Leukemia
Authors: Liu Qinyu , Zheng Wen , Yang Yunfan , Xu Caigang 
Published: December 2024

Background: T-lymphoblastic lymphoma/acute leukemia (T-LBL/ALL) is a severe hematological malignancy with challenging treatment and inconvenient monitoring methods in adults. To identify new biomarkers and potential therapeutic targets, we conducted a comprehensive metabolomic analysis of plasma samples from patients newly diagnosed with T-LBL/ALL using liquid chromatography-mass spectrometry technology.

Methods: Non-targeted metabolomic profiling was performed on frozen plasma samples from 30 newly diagnosed T-LBL/ALL patients between 2015 and 2018, compared with size-matched controls. Subsequently, based on the results of the initial analysis, the sample size was expanded to 50 patients' plasma samples and matched controls for targeted metabolomic validation. Mechanistic insights were explored using publicly available databases. Validation on the efficacy of detected biomarkers was done via retrospective data and limited prospective cases.

Results: Non-targeted profiling revealed significant differences in metabolic patterns between patient and control groups. KEGG pathway enrichment analysis highlighted methionine metabolism as a prominent hit. Random forest analysis confirmed the ability to distinguish cases from controls based on plasma metabolite differences (ROC curve AUC=0.9491, p&lt;0.001), with N-acetylspermidine being the most significant contributor. Expanded targeted validation experiments further confirmed significantly elevated N1-acetylspermidine (fold change=3.590, p&lt;0.001) in the patient group, effectively distinguishing them from the control (ROC curve AUC=0.888, p&lt;0.001). Patients with elevated N1-acetylspermidine had longer overall survival (median 15 months, 95% CI 10.77-19.24 vs 9 months, 95% CI 2.35-15.65, p=0.011) under chemotherapy only. Also, patients with normal N1-acetylspermidine levels showed poorer responses after induction chemotherapy (normal N1-acetylspermidine: CR 0(0%), PR 9(60.00%), SD 5(33.33%), PD 1(6.67%), vs. elevated N1-acetylspermidine: CR 7(24.14%), PR 17(58.62%), SD 3(10.34%), PD 2(6.90%); Mann-Whitney U test, p=0.030). By reviewing the GEO database GSE109231, we speculated that elevated N1-acetylspermidine levels might be linked to high expression of spermidine synthase (p=0.035, log2FoldChange=1.15).

We also analyzed plasma N1-acetylspermidine levels in a small prospective cohort, including 4 patients with newly diagnosed T-LBL/ALL and 1 with refractory relapse. Two newly diagnosed patients achieving CR exhibited a decrease in N1-acetylspermidine levels post-therapy (from 17.78ng/ml to 3.31ng/ml and 6.50ng/ml to 2.54ng/ml). The other two newly diagnosed patients, starting with non-elevated N1-acetylspermidine levels, showed minimal changes post-therapy (from 1.95ng/ml to 1.69ng/ml and 2.76ng/ml to 3.06ng/ml), achieving PR. The patient with refractory relapse, starting with much higher N1-acetylspermidine levels, experienced a significant increase post-therapy (from 47.80ng/ml to 119.37ng/ml), resulting in PD.

Conclusion: Metabolomic research has identified serum N1-acetylspermidine as a novel biomarker of T-LBL/ALL that is associated with better chemotherapy outcomes and may enable convenient therapeutic monitoring. Future studies should validate these findings in larger cohorts and also explore the underlying mechanisms at cellular and animal levels.