The recombinant factor IX product nonacog alfa appears safe and effective for patients with hemophilia B, according to results from a recent postmarketing study in Japan.
While nonacog alfa was approved in the United States and Europe in 1997, the product wasn’t approved in Japan until 2009. Since it was the first recombinant factor IX product available there, and only a small number of patients were enrolled in domestic clinical trials, the Japanese government required additional real-world studies.
“In the last couple of years, several extended half‐life blood coagulation factor products gained regulatory approval for the treatment of hemophilia B. However, access to this most advanced treatment option remains limited to developed countries, and the need for standard half‐life recombinant or plasma‐derived FIX products is still high,” wrote Katsuyuki Fukutake, MD, PhD, of Tokyo Medical University, Japan, and colleagues.
The researchers conducted an observational postmarketing surveillance study of 312 patients with hemophilia B who received nonacog alfa therapy from 2010 to 2014. The team evaluated the real-world safety, including the incidence of inhibitors and adverse events, and effectiveness of the recombinant product in Japan.
The findings were published in Haemophilia.
The study included both previously treated and untreated participants who were followed for 1 and 2 years, respectively, after starting recombinant factor IX therapy.
The primary safety outcome was the incidence and number of adverse drug reactions. Effectiveness was measured using clinical effectiveness rates and annualized bleeding rates (ABR).
After analysis, the researchers found that the effectiveness rates were 95.5% and 93.7% for patients who received routine prophylaxis and on-demand treatment, respectively.
The median ABR was lower during routine prophylaxis – 2.0 – versus the rest of the observation period – 8.3. “This difference was prominent among patients with severe haemophilia B or haemophilic arthropathy,” the researchers wrote.
With respect to safety, 11 adverse drug reactions were seen in seven previously treated patients. New inhibitor development was not observed in any participants, but recurrence was seen in one patient.
“Our results are consistent with those of previous studies where the incidence of inhibitor antibody development in hemophilia B has been reported as 1%-5%,” Dr. Fukutake and colleagues wrote.
The researchers acknowledged that one key limitation of the study was the observational design.
“The results suggest that nonacog alfa was well tolerated and appropriately used under routine clinical practice,” the authors concluded.
The study was funded and conducted by Pfizer Japan. The authors reported financial relationships with Pfizer and several other companies. One coauthor is an employee of Pfizer Japan.
SOURCE: Fukutake K et al. Haemophilia. 2019 Jun 6. doi: 10.1111/hae.13783.