GSK abandons cough drug added in $2bn Bellus deal

Three years after buying Bellus Health and its chronic cough candidate camlipixant for around $2 billion, GSK is abandoning the programme.

The pharma group said this morning that after reviewing data from the CALM-1 and CALM-2 phase 3 trials of camlipixant in adults with refractory chronic cough (RCC), it had concluded that "the limited efficacy demonstrated is unlikely to transform patient care" and it will no longer develop the drug for that indication.

Shares in the London-listed pharma group were trading down around 3.5% following the announcement.

Camlipixant is in the P2X3 antagonist class, which has seen other drug candidates fall by the wayside as RCC therapies, including Bayer's eliapixant, which was apparently scuppered by safety issues, and Shionogi's sivopixant, which failed to show efficacy.

MSD's gefapixant, which was rejected by the FDA for a second time in 2023, did reach some markets in Europe and Japan as Lyfnua for chronic, unexplained cough, but has not been a commercial success, never generating enough sales to feature in the company's financial reporting. One issue affecting the drug is reported to be high rates of taste-related side effects.

Camlipixant was the main asset that drove GSK's acquisition of Bellus Health in 2023, when MSD had its first Lyfnua approval in Japan, and despite a first rejection from the FDA was still pushing development of the drug in the US and other markets. At the time, camlipixant was already in the CALM-1 and CALM-2 studies, which were scheduled to read out towards the end of 2024.

Now, after a considerable delay, top-line data from the two pivotal studies reveal little more than glimmers of efficacy.

CALM-1 met its primary endpoint, with camlipixant at a dose of 50mg twice daily showing statistically significant reductions in 24-hour cough frequency versus placebo at week 12, but that result was not replicated in CALM-2.

Meanwhile, a lower 25 mg dose of the drug was found to lack efficacy in both studies, and camlipixant was also unable to move the efficacy needle on a series of secondary endpoints, including a Chronic Cough Diary (CCD) measure.

GSK has one more hope of a positive result with camlipixant, in the ongoing, phase 2b BALANCE trial in patients with irritable bowel syndrome, which is due to generate results next year.

There's no disguising the big disappointment of losing the RCC indication, however, which was seen as critical to meeting GSK's target of £2.5 billion ($3.4 billion) in peak sales for the drug, a crucial element in its plan to build annual revenues to more than £40 billion by 2031.

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