Application-level market taxonomy reveals how T-Cell Immunotherapy segmentation aligns with the oncological disease spectrum and manufacturing economics. Haematological malignancies (lymphoma, leukaemia, myeloma) account for the dominant revenue share because CD19 and BCMA antigens deliver high complete-response rates with manageable CRS/ICANS safety profiles, enabling outpatient administration and favourable HTA recommendations. Solid tumours—glioblastoma, melanoma, lung, breast, colorectal—represent a latent, high-value frontier where TCR-T and TIL modalities are being optimised to overcome antigen heterogeneity and suppressive microenvironments; current penetration is <5% but is expected to expand as combination regimens with checkpoint blockade mature. The paediatric subset, though numerically small, commands premium pricing due to orphan designations and accelerated regulatory paths. Finally, autoimmune applications (e.g., CAR-T for refractory lupus) constitute an exploratory pocket, valued for proof-of-concept data rather than near-term revenue. Collectively, application segments map directly to manufacturing scale, pricing flexibility and hospital infrastructure requirements, shaping investor allocation across the therapy pipeline.