TScan Therapeutics (TCRX) Status Update summary

Phase 1/Clinical Results and Efficacy

• TSC100 and TSC101 TCR-T cell therapies significantly reduced relapse rates (8% vs. 33%) and improved event-free survival (hazard ratio 0.3, p=0.04) in high-risk AML, MDS, and ALL patients post-transplant.

• All treated patients achieved full donor chimerism and MRD negativity post-infusion, including those with high-risk TP53 mutations.

• TSC cells persisted for over a year in all patients with sufficient follow-up, with higher persistence at the highest dose level.

• No dose-limiting toxicities were observed; safety profile was consistent with standard transplant, with similar rates of GVHD and CRS, and no cases of ICANS.

• Adverse events were low grade and manageable, with balanced acute GVHD rates between arms.

Regulatory and Pivotal Trial Planning

• FDA granted RMAT designation; pivotal trial will focus on TSC101, using an external control arm from CIBMTR for robust patient matching.

• Relapse-free survival accepted as the primary endpoint; pivotal study will enroll ~140 treatment-arm subjects with a 1:3 match to controls and a 24-month readout.

• Analytical comparability and potency assays are sufficient for pivotal study; no bridging study required.

• Study initiation planned for H2 next year, with readout expected in H2 2027.

• TSC-101 covers ~98% of HLA-A*02:01-positive patients, reducing need for companion diagnostics.

Market Opportunity and Expansion Strategy

• Initial addressable population is ~450 patients/year in the US, potentially expanding to 1,800 with changes in clinical practice; similar opportunity in Europe.

• Addressable patients could exceed 10,000 in the US and Europe with expansion to additional HLA types and heme malignancies.

• Pricing expected in the $500,000–$750,000 range, supported by recent TCR-T therapy approvals and early payer engagement.

• Pipeline expansion includes TSC102 for HLA-A*03:01, aiming to cover up to 55% of eligible patients; eight TCR-T candidates are in clinical development.

• Future directions include expanding to other HLA types, transplant settings, and potentially non-hematologic malignancies.