GSK's chronic hepatitis B therapy shows promise in key studies, analysts await full data

By Bhanvi Satija

LONDON, Jan 7 (Reuters) - GSK will use promising results from two studies of its experimental chronic hepatitis B therapy to support planned regulatory applications, it said on Wednesday, raising hopes of a functional cure for over 250 million people affected by the condition.

The British drugmaker did not disclose what proportion of patients showed sustained reduced levels of the virus DNA and surface antigens for six months or longer - the benchmark for functional cure - after treatment with the drug, bepirovirsen.

Analysts have said a rate of 15% to 20% of patients maintaining reduced levels of the two biomarkers, such that they are not detected by a test, would be considered significant for sufferers of chronic hepatitis B.

Despite the availability of safe, effective vaccines - including shots made by GSK – and significant advances in treatments, the condition remains prevalent and underdiagnosed, the World Health Organization says.

GSK plans to present full data at an upcoming scientific congress. Its shares were down about 1% in morning trade.

ANALYSTS OPTIMISTIC, BUT INVESTORS WILL NEED FULL DATA

"Whilst details in today's press release are limited, the consistency of the phase-three data is encouraging and should open blockbuster potential," Jefferies analyst Michael Leuchten said.

He added that the late-stage results confirm the efficacy seen in an earlier study of bepirovirsen, and he highlighted that there were no other therapies offering significant functional cure.

Striking a more cautious tone, J.P. Morgan analysts said that while meeting the studies' main goal was a minor positive for GSK, investors will focus on detailed data to assess whether the benefit is sufficient to drive broad adoption by patients.

GSK predicts bepirovirsen could bring in more than 2 billion pounds ($2.70 billion) in peak annual sales, taking the drugmaker closer to its annual revenue target of more than 40 billion pounds by 2031.

The study results represent an early win for new CEO Luke Miels, who took over from Emma Walmsley at the start of the year and has reiterated confidence in the company's revenue targets. Analysts currently forecast GSK's total revenues at about 35 billion pounds by 2031.

CHRONIC HEPATITIS B CAUSED A MILLION DEATHS IN 2022

Chronic hepatitis B is a long-lasting infection that occurs when the body is unable to fend off the hepatitis B virus and it persists in the blood and liver. It caused over a million deaths in 2022, according to the latest WHO estimates.

Current standard-of-care treatments only result in 1% to 4% of patients being cleared of the virus for a sustained period of time. One class of widely used therapies, known as nucleoside/nucleotide analogues, are often taken for life, because they suppress but rarely clear the virus. They can also cause serious complications.

GSK's bepirovirsen, which it licensed from Ionis Pharmaceuticals in 2019, blocks replication of the hepatitis B virus, reduces production of proteins linked to the infection, and activates the immune system.

($1 = 0.7407 pounds)

(Reporting by Bhanvi Satija and Pushkala Aripaka in Bengaluru; Editing by Subhranshu Sahu and Joe Bavier)