"I don't think we've explored the full capabilities if ibrutinib," Popplewell said.
Because of its accelerated review, the drug's approval by the FDA was based not on hard outcomes such as patients' survival or symptom improvement, but on trial investigators' assessment of the "overall response rate" of patients taking the drug. In a multi-center clinical trial that did not assign any subjects to take a placebo medication for comparison, 65.8% of 111 patients with mantle cell lymphoma were deemed to have responded to the medication, with 17% of the total achieving a "complete response" and 49% achieving a "partial response."
The median duration of patients' responsiveness to the medication was 17.5 months.
Ibrutinib is expected to be considered next by the FDA as a treatment for chronic lymphatic leukemia, a disease for which second-line treatment has been able to hold off progression for a median of 14 months. Ohio State University's Byrd said that roughly three-quarters of the patients he is overseeing in the trial are still taking the medication and doing well at the 26-week mark.
Johnson & Johnson and Pharmacyclics also announced some good news this weekend, stating that Imbruvica, its closely watched treatment for CLL and mantle cell lymphoma (MCL), was effective in treating CLL in a long-term (median follow-up period of 27 months) study of patients.
The FDA approved Imbruvica last month as a treatment for MCL, but some investors had expected it to be approved for CLL at the same time. Therefore, J&J and Pharmacyclics' recent announcement is definitely a positive indication that it could be approved for CLL as well. If approved for both, analysts believe that Imbruvica could eventually generate annual peak sales between $6 billion and $9 billion.
Sales of Imbruvica will be split evenly between J&J and Pharmacyclics. For J&J, it would mean another potential blockbuster to fill the gap left by Remicade -- the blockbuster arthritis drug that accounted for nearly a fourth of its pharmaceutical segment's revenue -- when its European patents start to expire in early 2015. For Pharmacyclics, which has no other marketed products, this could be its big chance to evolve from a speculative biotech into a fundamentally sound one.