It is a rare event, if not a singular one in the biopharma world: A first-in-class drug developed by multinational pharma companies was filed first—and now approved first—in China, well before the U.S., EU or Japan.

Chinese regulators have greenlighted FibroGen and AstraZeneca’s roxadustat for chronic kidney disease patients on dialysis. It marks the first nod in a new drug class called hypoxia-inducible factor prolyl hydroxylase inhibitor (HIF-PHI).

A potential challenger to Amgen and Johnson & Johnson’s blockbuster Epogen/Procrit, the drug isn’t a small asset that can be easily overlooked. Leerink Analyst Geoffrey Porges projected sales of about $1 billion in China alone by 2025, as a completed phase 3 has put it on track to expand into the larger nondialysis-dependent population.

The pair now expects to launch the drug in China in the second half of 2019, a slight delay as FibroGen’s Chinese manufacturing site was recently moved from Beijing to outside the city at the request of the government, a company spokesperson told FiercePharma. 

As for the U.S., the pair is wrapping up data readout for a regulatory submission in the first half of 2019. Through a separate agreement, Astellas is working with FibroGen in Japan, EU and other regions.

Roxadustat sailed through its Chinese regulatory journey under VIP treatment from the National Medical Products Administration (NMPA, formerly known as China’s FDA). It was put under an expedited review pathway last December, allowing it a rolling submission process that promises a decision within six months upon receiving full application files.

Positive China-specific phase 3 data formed the basis of the approval. In one study, of 256 dialysis-dependent CKD patients who received either roxadustat or Johnson & Johnson and Amgen’s Epogen/Procrit (sold in China by Kyowa Kirin) and completed the trial, roxadustat produced a numerically greater improvement in hemoglobin from baseline. The roxadustat group also showed a greater decline in bad cholesterol levels, another key indicator, because CKD-related anemia is often associated with cardiovascular disease.

In a separate phase 3 on 152 CKD patients not on dialysis, the drug achieved 1.9g/dL increase in hemoglobin, while a dummy drug saw a 0.4 g/dL decline. Approval for the larger indication will come after Chinese regulators complete inspections of trial sites, FibroGen said in a release Monday.

FibroGen and AZ are collaborating on roxadustat in China and the U.S., among other territories. While FibroGen is responsible for manufacturing, clinical development and regulatory affairs, AZ will take care of commercialization. AZ is a rising commercial power in China, enjoying nearly a fifth of its revenue from the emerging market, a far larger proportion than its multinational pharma peers.

Before a full launch, Porges said he expects FibroGen and AZ will begin engaging in reimbursement talks at the national and provincial levels. There’s a large market waiting ahead. Citing a 2012 study in The Lancet and data from China National Renal Data System, FibroGen estimated 120 million CKD patients live in China, including about half a million on dialysis who may be suffering from anemia, a number that’s been increasing significantly.

For China alone, Porges now forecasts the drug will register minimal sales during 2019, turn profitable by 2021 and jump to blockbuster status by 2025.