A US Food and Drug Administration (FDA) advisory committee voted 8 to 3 to recommend marketing approval of soluble ferric pyrophosphate (SFP; Triferic, Rockland Medical) as a parenteral iron agent to treat iron loss or iron deficiency and to maintain hemoglobin in adults with hemodialysis-dependent chronic kidney disease.
However, members of the Oncologic Drugs Advisory Committee also recommended to FDA staff members that Rockland Medical, based in Wixom, Minnesota, conduct postapproval studies, should the FDA go along with the committee’s recommendation, into the safety and efficacy of the agent during prolonged use.
SFP is delivered during hemodialysis through a 5-mL ampule containing 27.2 mg elemental iron added to water for injection. Rockland Medical said that Triferic, delivered three to four times a week during hemodialysis, can compensate for an estimated 5 mg of iron loss from dialysis-related blood losses.
The company submitted evidence in its application for approval that included results from two identical phase 3 trials in which investigators tested SFP against placebo. In both studies, according to the company, patients in the SFP group experienced a statistically significant and clinically meaningful difference of 0.36 g/dL over the placebo group between baseline and end of treatment (P = .011 for both studies), with a safety similar to placebo.
FDA staff members called into question, however, the reliability of the company’s data. Staff members pointed out that although treatment duration was planned for up to 48 weeks, only 18% of patients went that long in the trial, and 44% completed only 24 weeks. The various time values make it difficult to draw inferences, they said.
FDA staff members also pointed out that twice the number of deaths occurred in the SFP treatment group than in the placebo group (12 vs 6).
However, after a long discussion involving minute details of the study results, most committee members chose to support the recommendation to approve marketing Triferic, with advice that the research continue.
Lakhmir Chawla, MD, chief of intensive care medicine at the Veterans Affairs Medical Center in Washington, DC, who voted yes, said, “I compliment the sponsor for putting together a very difficult-to-do study…and I do think that these initial results are interesting and the mechanism is interesting. But I am concerned about the ability to dose properly.”
“I’m excited about the possibility of maintaining the iron level,” said Michael Flessner, MD, PhD, director of inflammatory renal diseases at the National Institute of Diabetes and Digestive and Kidney Diseases in Bethesda, Maryland, who voted yes. “I think that this study was well conducted, although complicated. I had to read it over about five times to understand it, but I do think in this case the applicants did show that this was an effective method of maintaining iron.”
Tito Fojo, MD, PhD, senior oncology investigator at the National Cancer Institute in Bethesda, said he voted no because he was not comfortable with the study and its results. “I thought the study was not all that well designed.”
Bernard F. Cole, PhD, a statistician and professor at the University of Vermont, Burlington, who voted no, said, “It was not a strong ‘no.’ I felt that the data show clearly that Triferic is active vs placebo….We have proof of principle, but in terms of clinical practice, I would have liked to see [the] study in a more realistic clinical setting.”
“I think the study as it was designed showed a benefit to the patients who received the treatment,” said panel Chair Deborah K. Armstrong, MD, professor of oncology at Johns Hopkins University School of Medicine, Baltimore, Maryland, who voted yes. “My concern is that the actual use of the drug will be quite different than it is from the data that was presented…. There needs to be some safety and potential efficacy studies looking into the prolonged use of the agent.”
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