Spherix Global Insights

July 27, 2021

Switching in Rheumatoid Arthritis: Will JAK Inhibitors Peak or Plummet?

By: Maxine Yarnall

There’s a reason why Spherix focuses on the new start and switching patient populations within the indications that we cover: it’s where brands have the opportunity to capture share. Whether a patient is initiated on or switched from one advanced systemic therapy to another, there is a window of opportunity for one brand to grab that piece of the pie – and manufacturers need to understand the driving forces behind this selection in order to optimize their commercialization efforts, or they may inevitably miss out.

Spherix has been tracking the evolution of the rheumatoid arthritis (RA) biologic/JAK inhibitor switch market through their RealWorld Dynamix™ service since 2016 in the US and 2017 in the EU. The TNF inhibitors (namely AbbVie’s Humira, Amgen’s Enbrel, UCB’s Cimzia, and Janssen’s Remicade and Simponi), as a class, have continued to dominate this segment in both geographies – albeit a slight downward trend in more recent years.

It wasn’t until the 2019 FDA approval of AbbVie’s Rinvoq when we saw a more dramatic shift in the US RA switch market towards alternate mechanisms of action – more specifically, the JAK inhibitors. That’s not to say the JAK class hasn’t been edging in on the TNFs since the introduction of Pfizer’s Xeljanz in 2012, competing head-to-head with front runner Humira. However, Xeljanz had essentially been fighting this class battle alone in the US, with little help from the FDA nod of Eli Lilly’s Olumiant in 2018.

Trended Brand Share in US Rheumatoid Arthritis Switching Market


Of note, preference for Olumiant remains higher in the EU, but momentum is growing for Rinvoq to become the second JAK of choice, displacing Xeljanz.

When examining the switch market, we go beyond the traditional chart audit approach – capturing the reasons behind switching off the prior brand and the reasons for choosing the new brand (on top of clinical patient labs, symptoms, non-clinical demographics, etc.). This allows us to gain additional insight into the “whys” behind which brands are winning and which are losing.

Spherix’s missed share analysis included in their RealWorld Dynamix™ service examines each audited patient’s “back-up” brand choice – that is, the agent they would have been prescribed had the switch-to brand not been available. Why did the rheumatologist and patient choose your competitor’s asset over yours? What could have been done differently to capture the share that was up for grabs? What does the profile of that “missed” patient look like?

Interestingly, while Xeljanz has been a consistent leader in the switch market, it has also been the brand that consistently leaves the most on the table – meaning it most often loses out to the brands that are ultimately prescribed to patients in this segment.

Trended Missed Share in US Rheumatoid Arthritis Switching Market


Will Rinvoq continue its path to market leadership with an even greater penetration in the RA switch market this year? Or will the results released in Pfizer’s post-marketing ORAL Surveillance study result in trepidation to prescribe these brands to patients in need of a new therapy – resulting in a sharp decrease in Xeljanz use and a halo effect for the JAK class?

The answers will be revealed to subscribed clients in the upcoming 2021 patient chart audits included in our US and EU RealWorld Dynamix™ services offered in the RA switching market. Contact us for more information.



RealWorld Dynamix™ is an independent, data-driven service unveiling real patient management patterns through rigorous analysis of large-scale patient chart audits. Insights reveal the “why” behind treatment decisions, include year over year trending to quantify key aspects of market evolution, and integrate specialists’ attitudinal & demographic data to highlight differences between stated and actual treatment patterns. Learn more about our services here.