TScan Therapeutics, Inc. recently announced updated results from the ongoing ALLOHA Phase 1 trial (NCT05473910) of TSC-101 in patients with heme malignancies undergoing allogeneic hematopoietic cell transplantation (HCT). The data was featured in a poster presentation at the 67^th American Society of Hematology (ASH) Annual Meeting and Exposition.

“These updated data from our Phase 1 study continue to highlight a positive safety and efficacy profile of TSC-101 in patients with heme malignancies undergoing allogeneic HCT. All three patients who reached two years of follow-up have no detectable disease as they have remained relapse-free and in complete donor chimerism,” said Chrystal U. Louis, M.D., Chief Medical Officer. “Additionally, there have been no dose-limiting toxicities and patients who received TSC-101 continue to show improved relapse-free and overall survival compared to control-arm patients. We remain focused on enrolling the remaining patients necessary to support our fixed-dosing regimen and look forward to initiating our pivotal study in the second quarter of 2026.”

“Bone marrow transplantation is currently the only curative treatment for patients with AML and MDS. Unfortunately, roughly 40% of these patients relapse within two years of transplant, at which point their prognosis is very poor and the majority will die due to their disease,” added Gavin MacBeath, Ph.D., Chief Executive Officer. “We are excited to see durable responses to TSC-101 and continued positive data, in the hopes of addressing this unmet need. We look forward to expanding our heme program in 2026 with product candidates designed to double the addressable patient population.”

Key Presentation Highlights

Patients in the treatment arm of the ALLOHA Phase 1 trial (NCT05473910) receive TSC-101 post standard of care HCT, whereas control-arm patients receive standard of care HCT alone. As of the September 19, 2025, data cut, 42 patients (23 in the TSC-101 treatment arm and 19 in the control arm) were eligible for inclusion in the safety analysis set. The key endpoints in the trial are safety and efficacy, with exploratory endpoints including donor chimerism and minimal residual disease (MRD) status. 

• Relapse-free survival (RFS) (HR=0.50; p=0.23) and overall survival (OS) (HR=0.61; p=0.52) were improved in the treatment arm relative to the control arm.
  -4 of 19 (21%) treatment-arm patients relapsed compared to 6 of 18 (33%) control-arm patients.
  -One treatment-arm patient with AML experienced disease relapse on day 161 and was given a third dose of TSC-101 without lymphodepletion. The additional administration of TSC-101 resulted in a complete response including complete donor chimerism that was maintained for 5 months.
  -The hazard ratio for probability of relapse was 0.46 (p=0.22).
  -8 of 37 (22%) patients had TP53 mutations, with 6 cases in the treatment arm and 2 cases in the control arm.
  -Of the 6 patients in the treatment arm, only 1 has relapsed. Both patients with TP53 mutations in the control arm have relapsed and subsequently succumbed to their disease. The first patient with a TP53 mutation to receive TSC-101 has now reached two years of follow-up and remains relapse-free.
• All 3 (100%) TSC-101-treated patients that reached two years of follow-up remained relapse-free as of the data cutoff, compared to 1 of 4 (25%) patients in the control arm, consistent with effective elimination of residual cancer cells post-HCT and durable remission with TSC-101 infusion.
• TSC-101 infusions were well-tolerated at all dose levels, with no dose-limiting toxicities. Observed adverse events were similar across the treatment and control arms and were generally consistent with post-HCT adverse events.
• Mixed chimerism or relapses following TSC-101 infusions were found to be significantly associated with greater ex vivo expansion of TCR-T cells during the manufacturing process. A new commercial-ready process reduces the manufacturing time from 17 days to 12 days and has a significant reduction in ex vivo

A copy of the presentation materials will be available in the Publications section of the Company’s website at tscan.com.

The Company recently announced that the US FDA has agreed to a pivotal study design for TSC-101 that mirrors the current ALLOHA™ Phase 1 trial using a biologically assigned internal control arm.

TScan is a clinical-stage biotechnology company focused on the development of T cell receptor (TCR)-engineered T cell (TCR-T) therapies for the treatment of patients with cancer. The Company’s lead TCR-T therapy candidate is in development for the treatment of patients with hematologic malignancies to prevent relapse following allogeneic hematopoietic cell transplantation (the ALLOHA Phase 1 heme trial). The Company has developed multiple TCR-T therapy candidates for solid tumors and is currently developing methods for in vivo engineering using these candidates. The Company is also applying their TargetScan platform to discover novel targets in various T cell-mediated autoimmune disorders.