GSK Pulls the Plug on Camlipixant After Mixed Phase 3 Results
GSK acquired camlipixant when it bought Bellus Health for $2 billion in 2023. Bellus had already started the CALM-1 and CALM-2 Phase 3 trials in patients with refractory chronic cough.
In CALM-1, the 50-mg dose significantly reduced 24-hour cough frequency at Week 12 compared with placebo. However, the same dose did not achieve a statistically significant reduction at Week 24 in CALM-2. Therefore, the second study missed its primary endpoint.
The 25-mg dose also failed to show statistical significance in either trial. Moreover, both studies missed key secondary endpoints. GSK consequently described the overall efficacy as limited and unlikely to transform patient care.
How One Failed Trial Crushed GSK’s Blockbuster Ambitions
GSK had expected camlipixant to become a major growth product. The company previously forecast peak sales of more than £2.5 billion, or approximately $3.4 billion.
However, the inconsistent Phase 3 results weakened the clinical evidence needed to support that commercial outlook. Although CALM-1 produced a positive result at Week 12, CALM-2 did not confirm the benefit at Week 24.
As a result, GSK lost a potential revenue driver that could have supported its target of reaching £40 billion in annual sales by 2031. The setback also removed what some analysts had viewed as one of the company’s most important clinical catalysts of 2026.
Camlipixant’s Setback Was About Efficacy Not Safety
The chronic cough program ended because camlipixant showed limited and inconsistent efficacy. The available results do not indicate that safety caused the failure.
GSK reported that the incidence and severity of treatment-related adverse events remained similar between the camlipixant and placebo groups. Therefore, the decision reflects an unfavorable efficacy profile rather than a major safety concern.
This distinction matters because Merck’s rival P2X3 inhibitor, gefapixant, faced problems with taste disturbances. Those adverse effects could also affect trial blinding. By contrast, GSK designed camlipixant to target P2X3 more selectively and reduce activity against P2X2 receptors in taste buds.
What the Failure Means for GSK’s $2B Bellus Health Bet
The result highlights the financial risk of acquiring late-stage drug candidates before pivotal trials establish consistent efficacy. GSK paid $2 billion for Bellus Health largely because camlipixant appeared capable of entering an underserved chronic cough market.
However, one positive primary endpoint could not offset the failed confirmatory study and missed secondary endpoints. Consequently, the case shows why pharmaceutical companies must evaluate reproducibility, clinical relevance and endpoint consistency when they assess acquisition targets.
The decision also illustrates portfolio governance in practice. Rather than continue investing in a program with limited potential to change patient care, GSK ended the chronic cough indication and redirected its development priorities.
Why GSK Is Still Testing Camlipixant Beyond Chronic Cough
GSK has not discontinued camlipixant completely. The company will continue a Phase 2b study in adults with irritable bowel syndrome.
GSK started the IBS trial in April 2026, and the study currently lists March 2027 as its primary completion date. Therefore, camlipixant may still have clinical and commercial value in another indication.
Still, the chronic cough failure changes the asset’s strategic position. Camlipixant no longer represents the blockbuster respiratory opportunity that supported the Bellus acquisition. Instead, its future now depends on whether the IBS program can produce clearer and more consistent evidence of patient benefit.
Mixed Phase 3 evidence can force pharmaceutical leaders to reassess development priorities, investment risk, and governance across the product lifecycle. Zamann Pharma’s Quality Management System service helps teams establish risk-based processes that support informed decisions, clear oversight, and sustainable quality governance.
Source: Fiercebiotech.Com