On Oct. 1, Jaqbo (zestaprazan citrate), a new potassium-competitive acid blocker (P-CAB) developed by Onconic Therapeutics—a subsidiary of Jeil Pharmaceutical—made its debut in Korea's competitive peptic ulcer market after being added to the national insurance plan. Despite high expectations, its arrival has been underwhelming, with sales falling far short of the explosive starts seen by its rivals.

According to Hit News, a Korean healthcare news outlet, Jaqbo saw 535.86 million won ($380k) in outpatient prescriptions in its first month—a solid start, but it pales in comparison to the dramatic debuts of earlier P-CAB drugs. 

When HK Inno.N  launched K-CAB (tegoprazan) in March 2019, it brought in a staggering 1.53 billion won in its opening month. Daewoong Pharmaceutical’s Fexuclue (fexuprazan), introduced in July 2022, followed closely behind with 1.07 billion won in prescription sales.

“We're essentially a latecomer,” acknowledged a Jeil Pharmaceutical official. Both Daewoong and HK Inno.N have already established strong positions in the market for acid-related treatments. Since its launch, K-CAB has reached 761.1 billion won in prescription sales as of September, while Fexuclue has accumulated 101.6 billion won in just two years.

Market data from IQVIA shows that the competitive landscape has shifted: success is no longer solely about increasing patient numbers but about winning the trust of doctors and patients, many of whom have already been swayed by the dominance of K-CAB and Fexuclue. “The competitors have already established themselves,” the Jeil Pharmaceutical official said. “It’s not easy for us to just step in and grab a piece of the pie.”

In response, Onconic Therapeutics is looking to carve out its own space, aiming to expand Jaqbo’s market share through a strategic partnership with Dong-A ST, formed in September. At the time of the announcement, Dong-A ST CEO Jung Jae-hun described the drug as “groundbreaking”—a medication that, in his words, could overcome the limitations of current treatments.

Jeil Pharmaceutical said it has also turned its full attention to Jaqbo. “This is our first new drug developed in-house,” said the company official. “We’ve poured significant resources into it. Naturally, there’s a lot riding on it.”

The pressure mounts when you look at the history of the market. From 2014 to 2019, no company had a double-digit market share in peptic ulcer treatments. But in 2019, K-CAB changed the game, propelling HK Inno.N  from relative obscurity to market dominance.

Just a year after its release, the P-CAB market had doubled in size, and by the following year, it had grown an additional 40 percent. When fexuprazan hit the market in 2022, the surge continued, pushing the P-CAB sector’s five-year compound annual growth rate to 53 percent.

As the P-CAB market continues to heat up, the outlook for Jaqbo remains uncertain. According to IQVIA, while P-CABs continue to dominate the market, with both tegoprazan and fexuprazan expected to sustain their growth, competition remains fierce. Adding to the pressure, over 20 Korean pharmaceutical companies are preparing to launch generic versions of Takeda's Vicinti (vonoprazan), ensuring that the high-growth P-CAB market will remain competitive in the years ahead.