TTI-101, a first-in-class oral inhibitor of STAT3 (signal transducer and activator of transcription 3), has shown promising results in a Phase 1 clinical trial for patients with advanced metastatic cancer. The study, published recently, evaluated the safety, pharmacokinetics, and preliminary efficacy of TTI-101 across multiple cancer types.
Targeting STAT3 in Advanced Cancers
STAT3 is a transcription factor crucial for cancer cell survival and immune evasion. TTI-101 is designed to selectively inhibit STAT3, disrupting these processes. The Phase 1 trial (NCT03195699) enrolled 64 patients with advanced solid tumors who had exhausted standard treatment options. Patients received TTI-101 orally twice daily in 28-day cycles at four dose levels: 3.2, 6.4, 12.8, and 25.6 mg/kg/day.
Safety and Tolerability
The trial demonstrated that TTI-101 was generally well-tolerated. No dose-limiting toxicities or fatal treatment-related adverse events (TRAEs) were observed. Diarrhea, mostly grade 1 or 2, was the most common TRAE, occurring in ≥30% of patients. Five patients experienced grade 3 TRAEs, which all resolved. Based on the safety profile and pharmacokinetic data, the recommended Phase 2 dose (RP2D) was determined to be 12.8 mg/kg/day.
Clinical Activity
Of the 41 patients evaluable for response, 5 (12%) achieved confirmed partial responses (cPRs), and 17 (41%) had stable disease. Notably, 3 of 17 patients with hepatocellular carcinoma (HCC) experienced a cPR, with a median time to treatment failure of 10.6 months. Additional cPRs were observed in one patient with ovarian cancer and one with gastric cancer, suggesting potential efficacy across different tumor types.
Ongoing Research and Future Directions
Given the encouraging results from the Phase 1 trial, TTI-101 is currently being evaluated in a Phase 1b/2 multicenter, open-label study (NCT05941335) focusing on patients with locally advanced or metastatic, unresectable hepatocellular carcinoma. This study is assessing TTI-101 as a monotherapy and in combination with immunotherapies such as pembrolizumab, or atezolizumab plus bevacizumab. The trial aims to determine the optimal dose and evaluate the efficacy of these combination regimens.
The development of TTI-101 represents a significant advancement in targeting STAT3 for cancer therapy. The ongoing trials will further define its role in the treatment of advanced cancers, particularly hepatocellular carcinoma, and its potential to enhance the effectiveness of immunotherapeutic approaches.
