Pfizer shouldn’t expect its rheumatoid arthritis drug tofacitinib to just swan into first line status and blockbuster sales.

Leerink Swan analyst Seamus Fernandez wrote Wednesday that a key opinion leader – and self-proclaimed fan of Bristol-Myers Squibb’s RA drug Orencia – expects the Pfizer drug will have to earn its place as a first-line treatment and will not be an immediate hit. Instead, Fernandez said the KOL, who spoke at a San Francisco investor meeting, indicated he expected tofacitinib will make its first impression as a second- or third-line treatment. This jibes with a May study by Reimbursement Intelligence which indicated payers would require patients to fail on at least two anti-TNFs before approving tofacitinib.

Fernandez wrote that the rheumatologist pointed to some hurdles, which includes her belief that the FDA may put its support behind the 5mg dose, as opposed to the 10mg dose. A lack of significant improvement at the higher dose gave an advisory committee pause when it reviewed the drug in May. Fernandez said the KOL also said tofacitinib will have to fight to differentiate itself from other in-development oral treatments, including AstraZeneca’s SYK inhibitor Fos-D, and Lilly’s JAK 1/2  inhibitor, among others. Fernandez added that the doctor said the key determinant will be Phase III data and safety and or/dosing profiles are set.

Tofacitinib’s FDA review has been an on-and-off again situation, due to data glut. The FDA requested supplemental testing data as well as time to sort through it, which has pushed its August review date to November.