TScan Therapeutics, Inc. announced that the first patient has been dosed in the Company?s Phase 1 trial evaluating TCR-T therapy for the treatment of solid tumors. The patient, diagnosed with metastatic melanoma, was dosed with TSC-203-A0201 targeting the cancer-associated antigen PReferentially expressed Antigen in MElanoma (PRAME). TScan?s Phase 1 clinical trial is designed to assess the safety and feasibility of T-Plex, autologous customized TCR-T therapy targeting multiple peptide/human leukocyte antigens (HLA) targets in participants with antigen-positive, locally advanced, unresectable or metastatic solid tumors.

Multiplex TCR-T therapy has the potential to overcome tumor heterogeneity and HLA loss of heterozygosity, commonly observed resistance mechanisms in solid tumors. First generation TCR-T therapies, targeting single antigens, have shown encouraging response rates in patients, but have often shown limited duration of response. TScan believes that its approach of dosing patients with more than one TCR-T targeting different cancer-associated antigens will result in increased response rates and increased duration of response.

To make this possible, TScan is screening patients (screening protocol: NCT05812027) with melanoma, non-small cell lung cancer (NSCLC), head and neck cancer, cervical cancer, ovarian cancer, anogenital cancers, and other solid tumors for target expression and the presence of intact HLA genes in their tumor cells. Eligible patients are then enrolled in the study treatment protocol (NCT05973487) and administered one or more investigational TCR-T products that are matched to cancer-associated antigens expressed in their tumors. This is made possible by the Company?s ImmunoBank, its repository of therapeutic TCRs that recognize diverse targets and are associated with multiple HLA types.

Currently, the ImmunoBank includes six TCR-T clinical candidates in Phase 1 development: TSC-203-A0201 (PRAME, HLA-A*02:01); TSC-200-A0201 (HPV16, HLA-A*02:01); TSC-201-B0702 (MAGE-C2, HLA-B*07:02); TSC-204-A0201 (MAGE-A1, HLA-A*02:01); TSC-204-C0702 (MAGE-A1, HLA-C*07:02); and TSC-204-A0101 (MAGE-A1, HLA-A*01:01). TScan intends to continue to expand the ImmunoBank with TCR-Ts for additional targets and HLA types, thereby increasing the number of patients that are eligible to receive multiplex therapy.