TCR Engineered Donor T-Cells

TSC-100 treatment arm (N=4: T-ALL, AML, AML, MDS)

• 4/4 patients treated with TSC-100 achieved complete donor chimerism with no relapse.

TSC-101 treatment arm (N=4: TP53-mutated MDS, AML, B-ALL, B-ALL)

• 4/4 patients treated with TSC-101 achieved complete donor chimerism with no relapse, including a patient with high-risk, TP53-mutated MDS who has reached one year of follow-up.
• One patient with AML was MRD-positive following HCT and converted to and maintained MRD-negative status following treatment with TSC-101 (most recent measurement at day 180).

TSC-100 and TSC-101 persistence noted for prolonged periods:

• Persistence of TSC-100 and TSC-101 was observed at all time points after dosing, with the longest follow-up of over 9 months.
• Repeat dosing (dose levels 2 and 3) led to a 3-fold increase in circulating TSC-100 and TSC-101 levels compared to single dosing (dose level 1) at the same time points.

Six control arm patients (MDS, MDS, MDS, AML, AML, AML) have been enrolled and received standard of care HCT alone:

• One control-arm patient with high-risk, TP53-mutated MDS evolved with MRD positivity and worsening mixed chimerism, experienced clinical relapse approximately six months post-transplant, and succumbed to relapse approximately nine months post-transplant.
• One control-arm patient with MDS experienced clinical relapse approximately five months post-transplant.
• One control-arm patient with MDS developed worsening mixed chimerism requiring early termination of immunosuppression, resulting in complete donor chimerism but with grade 1 skin graft-versus-host disease.
• One control-arm patient never achieved complete donor chimerism, with more than four months follow-up post-transplant.
• 2/6 control-arm patients achieved complete donor chimerism following HCT.