The GLP-1 market is one of the fastest-growing therapeutic spaces in biopharma history: valued at $66.4 billion in 2025, projected to reach $185.3 billion by 2033, with 60+ companies now developing GLP-1 drugs and upwards of 135 candidates in clinical trials.
That growth tends to focus attention on the science. But a recent formulary decision in the US has made something else impossible to ignore: clinical data alone won’t decide who wins the race.
What do the GLP-1 payer wars reveal about pharmaceutical commercialisation?
The rapid growth of the GLP-1 market highlights an increasingly important reality for pharmaceutical companies: clinical excellence alone does not guarantee commercial success. As competition intensifies, payer decisions, market access and commercial strategy are becoming just as influential as the science itself.
The recent CVS Caremark formulary reversal demonstrates exactly why.
Why does the CVS Caremark formulary decision matter?
The CVS Caremark decision shows that payer negotiations can reshape market access without any change in the underlying clinical evidence.
CVS Caremark, the largest pharmacy benefit manager in the US, recently announced it will restore coverage for Eli Lilly’s obesity products: Foundayo from June 2026, Zepbound from October 2026.
Here’s why the reversal matters.. For over a year, Zepbound had been excluded from standard formularies, handing Novo Nordisk’s Wegovy a clear advantage. Nothing changed in the underlying science. What changed was a payer negotiation, one that kept millions of patients from accessing the product through standard coverage, regardless of what their physician prescribed.
Why isn’t a strong clinical story enough to secure market access?
Most commercialisation strategies assume that a strong clinical story will naturally translate into payer access. Increasingly, that assumption no longer holds true.
Most commercialisation strategies carry an unspoken assumption: that a strong clinical story will translate naturally into payer access. But payers are motivated by different metrics.
- Regulators want to know whether a therapy is safe and works.
- Payers want to know how it performs against alternatives, at what cost, for which patients, and why now.
In a crowded space like GLP-1, the honest answer to “compared to what” is increasingly “something very similar, already on formulary”.
The clinical story is where the conversation starts, not where it ends.
But in practice, market access is still too often treated as what happens after the science. The payer value story gets built late, and cross-functional conversations that should start 24 months before approval happen in the weeks after it. By then the assumptions are baked in, and in a market moving as fast as GLP-1, they age quickly.
How can pharmaceutical companies build market access into commercialisation from the start?
The organisations best positioned for what’s coming are integrating market access into commercialisation planning from day one, assessing the payer landscape early enough to shape the clinical programme itself: which endpoints get prioritised, which comparators get selected, how patient populations get defined.
That requires genuine cross-functional alignment: a shared understanding of the payer challenge, what winning looks like, and what each function needs to deliver, not shared slide decks and quarterly updates. Where a single formulary decision can reshape the landscape overnight, that alignment can’t be a one-off exercise. It must hold as the evidence and competitive landscape shift.
Why is scenario planning essential for new drug launches?
Launch plans built around a single optimistic pathway are increasingly vulnerable. Scenario planning helps organisations prepare for the realities of changing payer landscapes.
Scenario planning is where this gets tested. Most launch plans are built around the optimistic pathway. Fewer map the alternatives:
- What happens if preferred formulary status isn’t secured in year one?
- What’s the response if a competitor locks in a more favourable net price?
- What happens if a major PBM changes coverage criteria mid-launch?
None of this was unforeseeable. Formulary exclusions, PBM negotiations and coverage reversals are established features of the US landscape. What made the CVS–Eli Lilly episode notable is that it happened to one of the most resourced commercial organisations in the industry, proving scale isn’t a substitute for preparation.
Are these challenges unique to GLP-1 therapies?
No. While GLP-1 provides a high-profile example, the same commercial dynamics affect drug launches across therapeutic areas.
These dynamics aren’t unique to obesity therapeutics. Formulary exclusions, payer decisions that override clinical differentiation, and unspoken access assumptions play out across every therapeutic area and market. Most don’t make headlines. They surface quietly, in launch post-mortems and revenue forecasts revised downward months after approval.
For the 60+ companies developing GLP-1 candidates, and every biopharma organisation with an asset in late-stage development, this is a moment of genuine clarity.
What should pharmaceutical companies learn from the GLP-1 payer wars?
The gap between clinical excellence and commercial reality doesn’t close with a strong data package alone.
It closes by naming assumptions, planning for access scenarios beyond the optimistic base case, and building cross-functional alignment early enough to matter: the work of building commercialisation strategies that resonate with patients, prescribers, and payers alike.