Metabolic Signatures of Dual mTOR Inhibition in Diffuse Large B-Cell Lymphoma

Diffuse large B-cell lymphoma (DLBCL) is an aggressive and heterogeneous malignancy in which many patients relapse or fail to respond to standard therapies. Constitutive activation of the mechanistic target of rapamycin (mTOR) pathway, involving both mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2), promotes tumor growth and metabolic reprogramming. First-generation inhibitors targeting mTORC1 alone have shown limited efficacy, partly due to incomplete pathway suppression and compensatory mTORC2 signaling. We evaluated Torin2, a potent ATP-competitive mTOR kinase inhibitor targeting both complexes, in four DLBCL cell lines with variable sensitivity to mTORC1 inhibition. In responsive models, Torin2 suppressed proliferation, induced apoptosis, impaired cell-cycle progression, and downregulated metabolic and proliferative transcriptional programs. Integrated metabolomic and transcriptomic analyses demonstrated broad inhibition of glycolysis, amino acid metabolism, and phospholipid biosynthesis. Torin2 reduced lactate and alanine levels detectable by noninvasive proton magnetic resonance spectroscopy ( ¹ H MRS) in vitro and in mouse xenografts, with metabolic changes paralleling tumor growth inhibition. Modulation of choline-containing metabolites further distinguished sensitive from less responsive tumors. These findings show that dual mTORC1/mTORC2 inhibition disrupts metabolic dependencies critical for DLBCL growth and identify ¹ H MRS-detectable metabolites as noninvasive pharmacodynamic biomarkers for response assessment and therapeutic stratification in mTOR targeted lymphoma therapy.