Results of Phase 1 Trial of Treg Adoptive Cell Transfer in Living Donor Kidney Transplant Recipients TRACT Therapeutics™

Regulatory CD4+CD25+FoxP3+ T cells Derived from the thymus and/or peripheral tissues Demonstrated to broadly control T cell reactivity Control immune responsiveness to alloantigens Contribute to operational tolerance in transplantation models TRACT Therapeutics Wood KJ and Sakaguchi S. Nat Rev Immunol. 2003 Mar;3(3):199-210.

Lymphodepletion to reduce numbers of circulating effector T cells may be an important adjunct to the use of Tregs as a cellular therapy in organ transplantation….

TReg Adoptive Cell Transfer (TRACT) in Clinical Transplant Patients Increased Regulatory T cells (Tregs) in the immune system have been associated with the elimination of rejection in transplantation by creating tolerance in the immune system Human Tregs can be isolated and expanded to large numbers while maintaining purity and potency Clinical trials of Tregs for GVHD, Inflammatory Bowel Disease, and Diabetes are underway TRACT Therapeutics

PHASE 1 TRIAL TREG ADOPTIVE CELL TRANSFER (TRACT) IN LIVING DONOR KIDNEY TRANSPLANT RECIPIENTS Design: Single center, open label, nonrandomized Objectives: Determine the safety of using expanded Treg Adoptive Cell Transfer (TRACT) Determine whether TRACT leads to transplant rejection/allosensitization and/or nonspecific immunosuppression Immune Monitoring TRACT Therapeutics

PHASE 1 TRIAL TREG ADOPTIVE CELL TRANSFER (TRACT) IN LIVING DONOR KIDNEY TRANSPLANT RECIPIENTS Methodology: dose escalation of expanded autologous nTregs in experimental arm (0.5, 1, and 5 x109 cells/subject , n=3 in each tier) Primary Outcome Measure: Patient and Graft survival @ 1year TRACT Therapeutics

Clinical Protocol TRACT Therapeutics Pretransplant collection of recipient lymphocytes via leukopheresis; cryopreservation of cells( 1 week - 1year Pretransplant) Day 0: Living Donor Kidney Transplant: Alemtuzumab Induction, Tacrolimus and Mycophenolate based IS; conversion from Tac to Sirolimus Day +30 Initiate isolation and expansion of autologous Tregs; infusion of expanded cells Day +60; protocol biopsy at 3 months and 1 year post-Tx TRACT Therapeutics

Isolation and Manufacture of Autologous Polyclonal Regulatory T cells Leukopheresis of recipient pre-transplant Immunomagnetic selection of Tregs (CD8,CD19 negative depletion, CD25 positive selection) from cryopreserved “raw product” Ex vivo culture and expansion of Tregs In process testing of expanded cells for phenotype, function, and sterility TRACT Therapeutics

Release Criteria for Expanded Tregs >70% cell viability CD4+/CD25+ > 70%; CD8+.CD19+ <10% endotoxin < 5 EU/kg gram stain negative; aerobic, anaerobic and fungal sterility mycoplasma negative residual bead count <3,000 beads per 108 cells >50% suppression at a 1:2 Treg:Teffector cell ratio in a mixed lymphocyte reaction TRACT Therapeutics

Summary All expanded cell products met release criteria  There were no infusion related serious adverse events  No evidence of over immunosuppression (opportunistic infections)  Post-infusion protocol biopsies at 3 months have been normal  Serial immunophenotypic analysis of subjects shows a sustained increase in circulating Tregs following Treg infusion TRACT Therapeutics

Conclusions Expansion of sufficient numbers of functional polyclonal Tregs from a cryopreserved leukopheresis product is feasible Infusion with polyclonally expanded Tregs up to 5x109 cells is safe TRACT was associated with an increase in circulating numbers of Tregs in the immune system Data supports the design and initiation of a Phase 2 trial TRACT Therapeutics