FDA sees potential in zelasudil for the treatment of idiopathic pulmonary fibrosis

On 21 August, the US Food and Drug Administration (FDA) announced that it had granted an orphan drug designation (ODD) to Redx’s zelasudil (RXC007), which is an oral, selective rho-associated coiled-coil containing a protein kinase 2 (ROCK2) inhibitor for the potential treatment of idiopathic pulmonary fibrosis (IPF).

This ODD will support Redx in its development of zelasudil and provide it with commercial incentives such as market exclusivity due to the high unmet need surrounding IPF.

Zelasudil is currently being investigated in a Phase IIa trial with topline data expected to be announced in the first quarter of 2024. The company is also planning a Phase IIb trial in IPF with zelasudil and standard of care over 12 months, with the evaluation of lung function through the use of forced vital capacity as the primary endpoint.

This suggests that the company is confident in zelasudil’s potential, as targeting ROCK2 is a novel approach for the treatment of IPF.

The IPF market is underserved with just two licensed pharmaceutical treatments available globally, Roche’s Esbriet/Pirespa (pirfenidone) and Boehringer Ingelheim’s Ofev (nintedanib), both of which were approved by the FDA in 2014.

Esbriet, a dual antifibrotic and anti-inflammatory agent, was launched in Japan in 2008 and in Europe in 2012. Ofev, a small molecule tyrosine kinase inhibitor, gained approval in Europe and Japan in 2015.

These two approved therapies slow the progression of fibrosis, but do not reverse it. Despite the small number of approved therapies for IPF, there is some activity in the late-stage pipeline landscape.

Pipeline assets include United Therapeutic’s Tyvaso (treprostinil), Boehringer Ingelheim’s BI-1015550, and FibroGen’s pamrevlumab. Both the FDA and European Medicines Agency granted treprostinil an ODD in 2020 to treat IPF, which boosted the profile of the agent and thus incentivised its further development.

The FDA granted BI-1015550 a breakthrough therapy designation and an ODD in February and August 2022, respectively. Moreover, the FDA granted pamrevlumab an ODD and fast-track designation in 2012 and 2018, respectively.

Pamrevlumab is the only agent in the late-stage pipeline with a fast-track designation, meaning FibroGen can frequently meet with the FDA and discuss the drug development plan, which can expedite the review process and potentially lead to faster drug approval.

Despite receiving an ODD, it is clear that zelasudil will face intense competition, the agent is still in Phase IIa development while the aforementioned pipeline agents are in Phase III.

ROCK inhibition has great potential to be a powerful therapeutic tool for the treatment of IPF, with ROCK signaling occurring across multiple sites and pathways, acting as key points that impact various downstream functions, (Somogyi, V, and others, 2019).

It is one of the most promising mechanisms of action in the pipeline and could potentially translate into a long-term solution for IPF patients, whereas current treatment options only slow disease progression.

Despite zelasudil’s strong potential, it is important to note that Redx is a new player that specialises in the early-stage clinical discovery and development of small molecule therapeutics.

The company has three active clinical programmes (zelasudil, RXC008, and RXC004) but no approved therapies, which may put it at a disadvantage to companies such as Boehringer Ingelheim, which has investigated and launched several products across many therapeutic areas.

However, Redx could pursue other routes when looking to increase the commercial awareness of its product, such as strategic partnerships with bigger and more experienced players in the space.

There is a high unmet need in the IPF space, which translates into a huge market opportunity that United Therapeutics, Boehringer Ingelheim, FibroGen, and Redx Pharma are all hoping to capitalise on as patients are still waiting for better treatment options.