RPTR-147 MTCs is our first clinical-stage program, currently in a Phase 1 dose-escalation trials. To enhance the efficacy of T cells against solid tumors in the absence of cytokine support, RPTR-147 IL-15 loaded MTCs. IL-15 is an effective immune agonist to support engrafted T cells, because it promotes T cell and NK cell proliferative expansion and activation.
In contrast to those other cytokines, such as IL-2, IL-15 does not promote generation of immunosuppressive regulatory T cells and causes limited toxic systemic exposure, but instead inhibits activation-induced cell death and promotes T cell survival and memory. Therefore, IL-15 is potentially an ideal cytokine to boost T cell anti-tumor activity as it builds upon the benefits, without the drawbacks, of cytokine modulation exhibited by some other cytokines.
The Phase 1 dose-escalation, multi-center clinical trial of RPTR-147, also referred to as our TT-101 clinical trial, is designed to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics and preliminary antitumor activity in patients with relapsed or refractory metastatic solid tumors. The TT-101 clinical trial tests the following two product candidates:
- RPTR-147:1 is primed with Antigen Set 1.0, comprised of PRAME, Survivin, NY-ESO-1, SSX2, and WT-1
- RPTR-147:2 is primed with Antigen Set 2.0, comprised of HPV16+ viral antigens (HPV16 E6 and HPV16 E7) and three additional tumor-associated antigens, or TAAs, (PRAME, Survivin and MAGE-A4).