Threshold Pharmaceuticals’ investigational hypoxia targeting agent, TH-302, in combination with gemcitabine, has met its primary endpoint in the Phase 2b clinical trial conducted in patients with first-line advanced pancreatic cancer.

The 214-patient multi-centre randomised controlled dose-ranging Phase 2b crossover TH-CR-404 clinical trial is designed to determine the efficacy and safety of two doses of TH-302 in combination with gemcitabine compared to gemcitabine alone.

In the Phase 2b study, patients were randomised equally into one of three cohorts: TH-302 at a dose of 240 mg/m2 plus gemcitabine, TH-302 at a dose of 340 mg/m2 plus gemcitabine, or gemcitabine alone.

The trial’s primary endpoint was progression-free survival, and the secondary endpoints included overall response rate, overall survival, change in CA19-9 as well as various other efficacy and safety parameters.

During the study patients treated with gemcitabine in combination with TH-302 at 240 mg/m2 and 340 mg/m2 reported 5.6 months of median progression-free survival (PFS) compared to 3.6 months for patients treated with gemcitabine alone.

In addition, the response rate in the combination arms was found to be 22% compared to 12% in the gemcitabine alone group.

The primary efficacy analysis was done based on 149 investigator-assessed PFS events and, per protocol, pooled data from the two gemcitabine plus TH-302 dose groups in comparison to gemcitabine alone.

Threshold Pharmaceuticals CEO Barry Selick said: "With the results of this trial, we are again very encouraged that TH-302 is conferring benefit to patients with aggressive and difficult-to-treat cancers. We look forward to its ongoing development with our partner Merck KGaA in this and other indications."

Threshold Pharmaceuticals Biostatistics and Clinical Operations senior vice president Stew Kroll said the study provides the proof of concept demonstration that TH-302 contributes to the efficacy of a known active agent and supports the rationale for combining TH-302, a hypoxia targeting agent, with other approved therapies.

To date, TH-302 has been investigated in over 550 patients in Phase 1/2 clinical trials, both as a monotherapy and in combination with chemotherapy treatments and other targeted cancer drugs.

Currently, the company is performing a Phase 3 trial of TH-302 in patients with first-line advanced soft tissue sarcoma (STS) to investigate the use of TH-302 plus doxorubicin compared with doxorubicin alone.