TScan Therapeutics, Inc. (NASDAQ:TCRX), 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, today presented data from Cohort C of the ongoing ALLOHA™ Phase 1 study, evaluating TSC-101 generated with the commercial-ready manufacturing process, in patients with heme malignancies undergoing allogeneic hematopoietic cell transplantation (allo-HCT).

"These data provide important support for our commercial-ready manufacturing process and reinforce our confidence in the consistency and quality of the product candidate being delivered to patients," said Gavin MacBeath, Ph.D., Chief Executive Officer. "We are very encouraged by the 11 of 14 patients who showed complete donor chimerism approximately three weeks after their first infusion as well as the complete chimerism seen in all 5 patients who were assessed after their second infusion of TSC-101. Furthermore, even in a higher-risk patient population when compared to patients in Cohort A and our control arm, 93% of patients responded to TSC-101 with decreasing recipient chimerism. Taken together, these findings support our planned transition into the pivotal Phase 3 study of TSC-101 this month. We look forward to advancing further development of TSC-101 with the goal of preventing relapse following allo-HCT and improving outcomes for these patients."

"The initial results from Cohort C continue to exhibit strong clinical efficacy while maintaining a positive safety profile in patients receiving TSC-101 after their standard of care allo-HCT," said Chrystal U. Louis, M.D., Chief Medical Officer. "This cohort enrolled ahead of schedule and highlights the strong investigator engagement and growing interest in the TSC-101 clinical development program. As relapse remains a leading cause of death following allo-HCT, we are encouraged by the potential of TSC-101 to address residual disease and thereby improve long-term outcomes for patients with heme disorders."

Key Data Highlights

  • 19 patients were enrolled in Cohort C:
    • ~90% manufacturing success rate (17/19) with commercial-ready process
    • 14/19 patients went to transplant and received their first infusion of TSC-101
      • 10/14 patients have received their planned second infusion, and 1/14 patients received a third infusion
    • 3/19 patients did not proceed to transplant due to clinical reasons
  • Chimerism data as observed by high sensitivity NGS assay (Alloheme) with assay cut-off of 0.2%:
    • 11 of 14 patients achieved complete donor chimerism within ~3 weeks of receiving their first infusion of TSC-101 and 2 of the remaining 3 patients are approaching complete donor chimerism
      • One patient with TP53 mutated AML remained in complete donor chimerism 6 months post-HCT
  • TSC-101 infusions were generally well-tolerated, safety was consistent with Cohort A, and observed adverse events were consistent with post-HCT adverse events.