Redx Pharma plans to conduct a Phase IIb study further investigating RXC007 in idiopathic pulmonary fibrosis (IPF), says Dr Jane Robertson, CMO at Redx. The trial is expected to start in mid-2024, after the completion and data readout of the ongoing Phase IIa study in H2 2023.
The results from the Phase IIa study (NCT05570058) will dictate the exact trial design and the number of doses that will be explored in Phase IIb, but it is known that it will be a randomised, placebo-controlled study on a background of standard therapies, she explains.
The primary endpoint will measure the change in the forced vital capacity (FVC) at around the 48-week time point, which is a regulatory-recognised endpoint measuring lung function.
The size of the Phase IIb study will depend on the number of doses and arms, but generally, such IPF trials have around 60 patients per arm. The ongoing Phase IIa study has 16 patients in each of the three cohorts, with 12 on active treatment and four receiving a placebo.
The Phase IIb will be a global study with sites in Europe, Robertson says. After this study is completed, Redx plans a registrational Phase III trial.
RXC007 is a small molecule inhibitor that targets Rho Associated Coiled-Coil Containing Protein Kinase 2 (ROCK2). ROCK2 is located at a nodal point in a cell signalling pathway and is believed to be central to fibrosis.
According to GlobalData’s Clinical Trial Database, there are 146 planned and ongoing Phase I–III clinical trials in IPF, with 67 studies in Phase I and 52 in Phase II. GlobalData is the parent company of Clinical Trials Arena.
Crohn’s disease compound will enter the pipeline
Redx is also planning to bring a new asset into clinical development, Robertson shares. The company is currently working on the non-clinical IND package for RXC008, a gastrointestinal (GI)-restricted ROCK inhibitor, which is being developed for fibrostenotic Crohn’s disease (CD).
Redx will start with a Phase I healthy volunteer study that is planned to begin at the end of 2023 or very early in 2024. Afterwards, a Phase I will be initiated in a small cohort of patients who already had a stricture and are at a high risk of developing a second one.
Robertson notes that this is an area of high unmet need as patients with CD who develop strictures tend to go on to develop more. “Anything that could reverse that fibrosis or reduce the risk of recurrent strictures could be a very valuable treatment,” she adds.
Indeed, only nine planned or ongoing clinical trials specify fibrosis, fibrostenosis, or strictures in their inclusion criteria. Out of those nine trials, none are investigating ROCK inhibitors. For comparison, there are a total of 431 ongoing or planned studies in CD.
The healthy volunteer study would aim to show that there are no systemic side effects. It will help to understand how much of the drug is present in the GI tract, and how far it can penetrate into the gut wall, the CMO shares.
RXC008 targets both ROCK1 and ROCK2, which are important enzymes in the fibrotic process. The systemic treatments are not able to target both enzymes because inhibiting them can cause severe hypotension and vasodilation. But because RXC008 is a GI-restricted compound, there is no systemic absorption in the process, Robertson explains.