While it’s all-hands-on-deck for frontrunners Gilead, AbbVie and Bristol-Myers Squibb in seeking to develop the first interferon-free, all-oral regimen in hepatitis C, Johnson & Johnson is fishing elsewhere for share of the HCV market — it’s looking for an initial approval with interferons and ribavirin.

And the FDA just gave the biotech a measure of validation, conferring on the application for simeprevir (or TMC-435), which was filed with the FDA March 28, the agency’s Priority Review status. Simeprevir, an investigational NS3/4A inhibitor, is being jointly developed by J&J’s Janssen and Sweden-based Medivir AB.

The regulator’s decision to fast-track the agent was likely motivated by two pivotal studies, Quest-1 and Quest-2, findings for which were released by the drug maker in April and are likely to become the basis for simeprevir’s NDA.

The trials studied the effects of simeprevir in patients with HCV genotype 1. One group of patients received simeprevir with pegylated interferon and ribavirin while another received only pegylated interferon and ribavirin. Patients in Quest-1 who received simeprevir saw a 91% sustained viral response (SVR, or cure rate) after 12 weeks and an 86% SVR12 in Quest-2.

J&J hopes simeprevir can carve out a niche among hard-to-treat patients with genotype 1. While it’s being studied with needle-based interferon, something that won’t necessarily win it any fans, simeprevir efficacy could. (It’s somewhat more efficacious than Vertex’s Incivek, according to an April research note from Julie Hoggatt from inThought, a unit of Symphony Health Solutions.)

Other drugmakers are moving away from HCV treatments with interferon and ribavirin due to their debilitating side effects. Peglayted Inteferon must be administered intravenously and can cause flu-like symptoms. Ribavirin can cause hemolytic anemia—which worsens pre-existing cardiac conditions, and typically requires testing before beginning a regimen.

“Patients with genotype 1a…can be particular challenging to cure,” said Maria Beumont, the Janssen medical leader for simeprevir, in a statement, “Janssen is committed to advanced hepatitis C therapy for even the most difficult-to-cure patients.”

Peak sales estimates for simeprevir are expected to be $647 million in 2017, according to the same inThought research note. This figure pales in comparison to the $4.3 billion estimate in peak worldwide sales for Gilead’s sofosbuvir.

While it may only fit a small unmet need for genotype 1, simeprevir may live on in other all-oral combos. The drug is currently in trials (dubbed COSMO) with Gilead’s sofosbuvir and has shown potent efficacy—with SVR8 rates of up to 100%. In July 2012, J&J also announced it would begin trials testing simeprevir in combination with BMS’s daclatasvir, as well.

Janssen has also filed simeprevir for regulatory approval in Europe and Japan.