GRADUATE ASSISTANT texas tech university health science center ABILENE, Texas, United States
Introduction/Rationale: T-cell acute lymphoblastic leukemia (T-ALL) develops from the malignant transformation of immature T cells and is marked by a low mutational burden and limited neoantigen landscape, making immunotherapy challenging. Therefore, it is uncertain whether T-ALL can produce leukemia-specific T cells that could benefit from immunotherapy.
Methods: Using a murine model, CD45.2⁺ T-ALL cells from spontaneously leukemic mice were transplanted into immune-competent CD45.1⁺ hosts to monitor leukemia-specific T-cell responses. NUR77, OT-I, and OT-II transgenic mice were employed to distinguish TCR-driven activation from non-specific expansion, while single-cell RNA sequencing characterized immune heterogeneity and activation states. Ex vivo cytokine assays evaluated functional capacity, and therapeutic efficacy of αCD40 and αPD-1 was tested in vivo.
Results: T-ALL elicited robust leukemia-specific T-cell responses despite low antigenicity. Effector-memory T cells expressing PD-1, TOX, and FoxP3⁺ Tregs were enriched, reflecting chronic activation and exhaustion. Cytokine profiling revealed reduced IL-2 but elevated IFN-γ, consistent with ongoing immune engagement. OT-I/OT-II experiments confirmed that exhausted PD-1⁺TOX⁺ subsets were antigen-specific. NUR77 transgenic data validated TCR-dependent activation. Myeloid populations upregulated PD-L1, suggesting suppression of T-cell activity via PD-1 signaling. Combination immunotherapy with αCD40 (to activate APCs) and αPD-1 (to reverse exhaustion) produced synergistic effects, prolonging survival and achieving complete remission in ~50% of treated mice. Re-challenge confirmed durable antitumor memory.
Conclusion: Despite low mutational burden, T-ALL generates functional leukemia-specific T cells that can be reactivated through combined myeloid and checkpoint modulation. Dual targeting with αCD40 and αPD-1 represents a promising immunotherapeutic approach for enhancing leukemia clearance and long-term immune protection.
