TScan Therapeutics (TCRX) Status Update summary

Hematologic malignancy program update

• Phase 1 ALLOHA trial of TSC100 and TSC101 in AML, MDS, and ALL showed a significant reduction in relapse rates (8% vs. 33% control) and improved event-free survival (hazard ratio 0.3, p=0.04).

• TSC100/101 infusions were well tolerated, with no dose-limiting toxicities and a safety profile similar to standard transplant.

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

• TCR-T cells persisted for over a year post-infusion, with higher persistence at the highest dose level.

• Adverse events of special interest were low grade and manageable, with no cases of ICANS and balanced acute GVHD rates.

Pivotal trial design and regulatory feedback

• FDA granted RMAT designation; pivotal trial will focus on TSC101, using an external control arm from CIBMTR and relapse-free survival as the primary endpoint.

• FDA RMAT meeting confirmed analytical comparability and potency assays are sufficient for pivotal study.

• Pivotal trial initiation is planned for H2 next year, targeting ~140 treatment subjects, with a 1:3 match to controls and a 24-month readout.

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

• Use of an external control arm from CIBMTR is acceptable for full approval.

Market opportunity and expansion

• Initial addressable population in the US is ~450 patients/year, potentially expanding to 1,800 with shifts in clinical practice; Europe could add up to 3,000 more.

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

• Pricing is anticipated in the $500,000–$750,000 range, supported by recent approvals and payer research.

• Pipeline expansion includes TSC102 for HLA-A*03:01, aiming to cover up to 55% of eligible patients, with IND filing planned for 2025.

• Additional expansion opportunities include other HLA types, transplant settings, and non-hematologic malignancies.