In this episode of Topical Conversations, James Q. Del Rosso, DO, gives an overview of the emerging role of the OX40/OX40 ligand (OX40/OX40L) pathway in the treatment of atopic dermatitis (AD). As research continues to advance, this pathway has gained attention as a promising therapeutic target that could offer longer-lasting relief for patients with AD by addressing the root causes of inflammation. 

What is the OX40/OX40 ligand pathway? 

The OX40/OX40 ligand pathway is a key regulatory mechanism in the immune system, playing a crucial role in the communication between immune cells. Specifically, this pathway is believed to govern type 2 inflammation, which is central to the development of AD, at its source. OX40, found on activated T lymphocytes, and OX40 ligand, present on antigen-presenting cells, act as costimulatory molecules that enhance the activation and proliferation of T cells, particularly Th2 lymphocytes. This T cell activation leads to the chronic inflammation characteristic of AD. 

Dr Del Rosso explains that when this pathway is activated, it not only contributes to the immediate inflammatory response but also influences immune memory. This means that the pathway helps sustain the immune system's ability to reactivate inflammation during flare-ups and may contribute to the persistence and recurrence of AD over time. 

Targeting OX40/OX40 ligand in AD treatment 

Given the critical role of the OX40/OX40L pathway in driving inflammation and disease recurrence, blocking this pathway has become a focus for new AD therapies. Two agents are currently under investigation—amlitemab, which binds to OX40 ligand, and rocatinlimab, which targets OX40. Both therapies aim to inhibit the expansion of T cells that lead to the acute flares seen in AD and block the memory T cells responsible for long-term recurrence. 

By interfering with this pathway, these treatments have the potential to work on 2 levels: reducing the severity of current flares and preventing future ones. This dual action could represent a significant advancement in AD management, moving beyond symptom control to more durable, long-term disease modification. 

A paradigm shift in AD treatment 

As Dr Del Rosso emphasizes, paying attention to the OX40/OX40 ligand pathway is critical as it represents a novel approach to treating AD at its source. By addressing the underlying mechanisms that drive both acute and chronic inflammation, these therapies could transform how dermatologists manage AD, offering patients not only symptomatic relief but also the possibility of long-term remission. 

For more on this topic, tune in to the Derms and Conditions episode, The OX40/OX40L Pathway: Expanding Our Understanding of Atopic Dermatitis