The interim results of this Phase I/II study of targeted gene delivery in vivo are very encouraging – intravenous infusions of Rexin-G demonstrated significant biological activity without toxicity in patients with rapidly progressive chemo-resistant breast cancer. Once the general safety of repeated infusions of Rexin-G was documented, the FDA approved across the board intra-patient dose-escalations in order to gain better tumor control.
These escalating doses of Rexin-G were associated with stabilization of disease, using both Recist and International PET criteria, significant reductions in CA 15.3 levels, a median progression-free survival of six months (Recist) and a median over-all survival of greater than seven months with all patients surviving at the eight-month follow-up period.
No dose-limiting toxicity was observed, even at the higher doses of Rexin-G, thus confirming that repeated infusions of Rexin-G are safe and well-tolerated.
Taken together with the results of previous studies, the current on-going Phase I/II study confirms the exemplary safety and therapeutic potential of Rexin-G in chemotherapy-resistant metastatic breast cancer.