TCA cycle mode switch determines the fate of pirtobrutinib-tolerant persister cells in mantle cell lymphoma

ABSTRACT: Bruton tyrosine kinase inhibitors (BTKis) and cell therapy have successfully been used to treat mantle cell lymphoma (MCL). However, therapy resistance inevitably emerges. Cancer cells can progressively develop stable resistance by traversing through a transient drug-tolerant persister (DTP) state. The mechanisms enabling DTP cells to reversibly adapt to therapies and evolve to acquire heterogeneity remain poorly understood, and characterizing DTP cells in MCL continues to pose a challenge for clinic translation. Here, using pirtobrutinib, a recently US Food and Drug Administration-approved noncovalent BTKi, we identified pirtobrutinib-tolerant persister cells exhibiting morphological variability by presenting a unique population of enlarged cells (giant cells) with reversible fate transitions. During treatment, giant cells enter a nonproliferative, dedifferentiated state, addicted to an activated cytosolic tricarboxylic acid (TCA) cycle coupled with the malate-aspartate shuttle to engage in biosynthesis. Upon drug removal, the TCA cycle shifts to oxidative catabolism, promoting giant cells to differentiate into regular-sized cells. Throughout the transition, acetyl coenzyme A modulates cell fate by fine-tuning stemness. Our biphasic model demonstrates that the metabolic switch governs the phenotypic plasticity of DTP cells in MCL, resulting in a dynamic presence of DTP cells across various developmental states in response to systemic therapies. Targeting giant cells before their differentiation offers a promising strategy to overcoming therapy resistance in MCL.