Utilizing patient-derived organoid tumor models to combat chemo-immunotherapy resistance in NSCLC

Immune checkpoint inhibitors (ICIs) have transformed the treatment landscape for non-small cell lung cancer (NSCLC), yet only a subset of patients achieves durable benefit due to primary and acquired resistance. We previously reported elevated kynurenine (KYN) in cisplatin-resistant NSCLC. KYN, produced by indoleamine 2,3‑dioxygenase 1 (IDO1) and tryptophan 2,3‑dioxygenase (TDO2), promotes immune evasion by diminishing CD8⁺ T‑cell responses and expanding regulatory T cells (Tregs). Clinical failure of selective IDO1 inhibition in cancer suggests compensatory TDO2 upregulation as one of the resistance mechanisms. To target redundant KYN production, we evaluated the efficacy of a dual IDO1/TDO2 inhibitor (AT‑0174; Antido Therapeutics) in preclinical models of cisplatin-resistant NSCLC. Efficacy and mechanism were assessed in vivo via a syngeneic orthotopic mouse model. Dual inhibition significantly reduced tumor volume (n=10, p<0.01) and prolonged survival in the mouse model. These effects correlated with increased activity of CD8⁺ T cells and natural killer (NK) cells, as well as reduced frequencies of immunosuppressive Tregs and myeloid-derived suppressor cells (MDSCs). Combining AT‑0174 with anti‑PD‑1 therapy produced a synergistic effect, further suppressing tumor growth and significantly improving survival in mice (log‑rank, p=0.0001). We then developed a patient-derived organoid tumor (PDOT) platform that closely recapitulates the molecular and metabolic features of each patient's NSCLC. Single-cell RNA sequencing demonstrated ~70% transcriptional similarity to original tumors, and metabolomic profiling confirmed comparable pathway activity. IDO1 protein was detected in all PDOTs. Co-culture with patient-matched PBMCs revealed that PDOTs with high baseline PD-L1 and kynurenine (KYN) expression were highly sensitive to dual IDO/TDO inhibition combined with pembrolizumab, resulting in increased immune cell infiltration (n = 10, p < 0.005). This microfluidic PDOT system enables functional, patient-specific assessment of KYN pathway reliance, supporting timely stratification of NSCLC patients and rational design of combination regimens integrating metabolic targeting with immune checkpoint inhibitors. These findings provide a strong rationale for clinical evaluation of dual IDO/TDO inhibitors alongside checkpoint blockade.