Rebinyn Compares Well to Two Other FIX Therapies: Real-life Study

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by Steve Bryson PhD |

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Hemophilia B patients who switched to Rebinyn (nonacog beta pegol), an extended half-life factor IX (FIX) replacement therapy, had similar or better responses than with their previous standard or extended half-life FIX replacement therapies, a real-world study in Canada suggested.

The study, “Switching to nonacog beta pegol in hemophilia B: Outcomes from a Canadian real-world, multicenter, retrospective study,” was published in the journal Research and Practice in Thrombosis and Haemostasis.

Hemophilia B is mainly treated through replacement therapy, in which a modified version of the missing FIX blood-clotting protein is infused into patients, either to stop bleeds (on-demand) or to prevent them (prophylaxis).

Traditional concentrates of recombinant, or lab-made, FIX (rFIX) require frequent infusions that can affect treatment adherence and patients’ quality of life. Extended half-life recombinant FIXs are modified to prolong FIX exposure, aiming to reduce the burden of prophylaxis through less frequent dosing.

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Two extended half-life products include Alprolix, in which FIX is fused to an Fc protein, and nonacog beta pegol (N9-GP) — marketed in the U.S. and Canada as Rebinyn and as Refixia in Europe — which attaches FIX to a molecule called polyethylene glycol (PEG).

Researchers at the University of Calgary and colleagues analyzed real-world treatment outcomes in a group of boys and men with hemophilia B who switched to Rebinyn from standard half-life (SHL) rFIX or from Alprolix.

Patient data was collected from the Canadian Bleeding Disorders Registry, which captures information from 24 hemophilia treatment centers and patients across Canada.

Data covered 42 male hemophilia B patients, ranging in age from 7 to 72, with most (76.2%) between ages 18 and 65. Of them, 26 (62%) had severe hemophilia, 15 (36%) had moderate, and one (2%) had mild disease.

Before switching to Rebinyn, 26 patients were using Alprolix, while 16 received SHL rFIX. All treatments were given on a prophylactic basis, with a median treatment period of 1.4 years for both therapies.

After switching to Rebinyn, the median treatment period was 2.3 years, with 26 patients completing two or more years of treatment.

Overall, the median annualized bleeding rate (ABR), measured in bleeds per patient per year, was significantly lower for those who switched to Rebinyn from SHL rFIX (2.10 vs. 6.06). The ABR was also lower with Rebinyn compared with Alprolix (0.73 vs. 1.44), but this difference was not statistically significant.

Likewise, there was a significant reduction in recurrent bleeding episodes when patients switched to Rebinyn from SHL rFIX, but no difference in recurrent bleeds after switching from Alprolix to Rebinyn.

During follow-up, 232 breakthrough bleeds were reported in 30 (71%) patients while on Rebinyn prophylaxis. Of these, 186 (80%) were joint bleeds. A total of 16 (38%) patients reported no joint bleeds, and 12 (29%) had no bleeds at all.

The proportion of bleeds requiring only one infusion to stop bleeding was higher when patients were being treated with Rebinyn than when they were on SHL rFIX (90.2% vs. 73.2%). In those who switched from Alprolix to Rebinyn, there was no difference in the proportion of bleeds requiring only one infusion (72% vs. 71%).

The overall median total annualized FIX usage was lower with Rebinyn after switching from SHL rFIX (2,152 vs. 3,018 IU/kg) and Alprolix (1,766 vs. 2,278 IU/kg). Results were similar for prophylaxis and on-demand FIX.

The overall annualized FIX treatment frequency, for both prophylaxis and on-demand, was also lower with Rebinyn than SHL rFIX (50.5 vs. 57.6) and Alprolix (39.24 vs. 51.0), as was the recorded prophylactic dosing frequency (median number of infusions per week) with Rebinyn compared with SHL rFIX (1.0 vs. 1.1) and Alprolix (0.8 vs. 1.0).

Altogether, 17 surgeries were reported in patients treated with Rebinyn, leading to a median FIX consumption of 84.5 IU/kg over a period of 14 days following surgery. No adverse events were reported throughout the analysis.

“This study provided the first report of the efficacy and safety of [Rebinyn] in a real-world setting,” the scientists wrote. “The results of this study suggest that [Rebinyn] compares favorably with both SHL rFIX and [Alprolix] in terms of improved bleeding outcomes and reduced rFIX consumption.”