TTI-621-02 (NCT02890368) is a multicenter, open-label phase 1 trial of TTI-621 in patients with relapsed or refractory percutaneously accessible solid tumors or mycosis fungoides (a form of cutaneous T cell lymphoma). In this study TTI-621 is administered directly into the tumor (intratumoral dosing). Most patients on this study receive TTI-621 as a monotherapy; for some tumor types, TTI-621 may be administered with pegylated interferon-alpha, a PD-1/PD-L1 inhibitor, an oncolytic virus or radiation. The objectives of this study are to characterize the safety and tolerability of intratumoral TTI-621, to determine the recommended dose/regimen, and to gain preliminary evidence of the anti-tumor activity of TTI-621 following local administration. Detailed evaluation of serial, on-treatment tumor biopsies of both injected and non-injected cancer lesions will help characterize tumor microenvironment changes anticipated with CD47 blockade.
Preliminary data from this study were recently reported at the 2017 American Society of Hematology Annual Meeting. Intratumoral injection was well tolerated, with no dose-limiting toxicity observed. A rapid reduction in CAILS scores, which measures local lesion responses, was observed in 9 out of 10 mycosis fungoides patients and a reduction in circulating leukemic Sézary cells was observed in 3 out of 3 patients. Several patient profiles were presented which demonstrate clinical responses in disfiguring lesions, in some cases after a single dose of TTI-621.