GSK bolsters respiratory pipeline with Bellus Health buy

GSK has agreed to acquire Canada’s Bellus Health for around $2 billion, bolting on a late-stage drug candidate for chronic refractory cough.

The $14.75-per-share deal will add P2X3 antagonist camlipixant to GSK’s respiratory pipeline, a drug which the UK-headquartered big pharma reckons could be ready for launch in 2026, although it is in a class that has seen some challenges.

Last year, Bayer abandoned development of its P2X3 antagonist eliapixant, despite promising efficacy data in chronic cough studies, on what appeared to be safety concerns.

That announcement came shortly after Merck & Co’s rival candidate gefapixant was turned down by the FDA, apparently because of issues with the method it used to count 24-hour cough rates in pivotal trials. Merck has said it should be ready soon to refile the drug, which is already approved in Japan as Lyfnua.

Buoyed by that delay, GSK has swooped on Bellus’ programme, which already has an agreement with the FDA on the cough recording system used in its phase 3 programme, which includes the CALM-1 and CALM-2 studies due to read out in the latter half of 2024.

That timeline still gives Merck a chance to be first to market, if the FDA is happy with a new analysis from its studies, but GSK is hoping for ‘best-in-class’ data that could make camlipixant the go-to drug in the category. It has pointed to a lower tendency to cause taste disturbances (dysgeusia) than other compounds in the class.

In the phase 2b SOOTHE trial reported in 2021, camlipixant was shown to be effective at reducing 24-hour cough frequency with twice-daily 50 mg and 200 mg oral dosing, reducing the rate versus placebo by 34% at day 28.

The company said in the announcement to disclose the takeover offer that camlipixant has “significant sales potential through 2031” as a first-line treatment for adults with refractory chronic cough.

There are currently no approved treatments for refractory chronic cough in either the US or the EU, and the condition is estimated to affect somewhere between 5% and 10% of people worldwide. Analysts have suggested that the first P2X3 drug to reach the market could generate annual sales of $500 million or more.

Also active in this area is Japanese drugmaker Shionogi, which has a P2X3 drug called sivopixant (S-600918) in mid-stage clinical testing for chronic cough, neuropathic pain and sleep apnoea.

GSK has a five decades-long heritage in respiratory medicines with drugs like severe asthma therapy Nucala (mepolizumab) and asthma/chronic obstructive pulmonary disease (COPD) therapies like Trelegy (fluticasone furoate/umeclidinium/vilanterol), so is a good match for camlipixant.

The big pharma needs to boost its pipeline as it is facing patent expiry in 2027 for HIV drug dolutegravir, one of its biggest sellers, and could see new competition for shingles vaccine Shingrix, currently its top product.