Safety signals seen for cancers and erosions
Dr. Parfrey cited two particular safety findings, both seen in ASCEND-ND. One was a numerically higher rate of cancer-related death, or tumor progression or recurrence, among the daprodustat recipients (3.7%), compared with the controls who received an ESA in the ASCEND-ND trial (2.5%), representing a significant relative risk of 1.47.
In contrast, in ASCEND-D this cancer safety measure showed a reduced relative risk with daprodustat of 0.92 relative to the ESA comparators.
“The safety of HIF-PHIs from the cancer perspective will require longer follow-up, individual patient meta-analysis ... and postmarketing surveillance,” wrote Dr. Parfrey, a nephrologist and professor at Memorial University, St. John’s, Nfld.
Elevated cancer rates are a hypothetical concern with agents from the HIF-PHI class because of their potential for increasing angiogenesis that could support tumor growth, said Dr. Wish.
Dr. Parfrey also cited another safety signal in ASCEND-ND, a higher rate of esophageal or gastric erosions on daprodustat (3.6%), compared with those on darbepoetin alfa (2.1%), with a significant relative risk of 1.7.
Again, this signal was absent in ASCEND-D, where esophageal or gastric erosions were more common in the patients on an ESA, with a relative risk reduction in favor of daprodustat of 0.74.
But even if these cancer and erosion effects in nondialysis patients on daprodustat are real, “these things don’t sink a drug. You deal with them in the drug’s label,” commented Dr. Wish.
During the FDA’s advisory committee meeting on roxadustat, agency staffers especially cited apparent excess rates of thrombosis and seizures associated with the drug. In both ASCEND-D and ASCEND-ND the rate of seizures in both treatment arms was less than 1%.
Dr. Wish speculated that the differences seen between roxadustat and daprodustat are likely more related to the design of their respective studies rather than real drug differences within the class.
Perhaps most importantly, the roxadustat trials in patients with CKD and not requiring dialysis compared the drug against placebo, while in ASCEND-ND the comparator was darbepoetin alfa. He also suggested that patients on dialysis receiving roxadustat may have been “overdosed,” resulting in faster increases in hemoglobin and higher peak levels.
Big potential for oral anemia treatment
In general, having an oral alternative for treating anemia in patients with CKD will be a significant advance, said Dr. Wish, especially for patients not on dialysis as well as for the rapidly growing number of patients who receive dialysis at home.
U.S. patients with CKD who do not require dialysis “often don’t get treated for anemia because it is so cumbersome” to use ESAs on patients not treated at a centralized clinic, said Dr. Wish, medical director of the outpatient dialysis unit at Indiana University Hospital, Indianapolis. “It’s a logistical nightmare.”
On the other hand, Wish did not see nearly as great a need for an oral therapy for anemia in patients treated at a dialysis clinic.
Patients who receive an ESA during their three-times weekly dialysis session usually do very well. “It’s not broken, and does not need to get fixed,” Dr. Wish said.
ASCEND-D and ASCEND-ND were sponsored by GlaxoSmithKline, the company developing daprodustat. Dr. Singh has been a consultant to GlaxoSmithKline and owns stock in Gilead. Dr. Wish has been a consultant to GlaxoSmithKline, as well as an adviser to AstraZeneca, Akebia, Otsuka, Vifor, and Rockwell Medica, and he has been a speaker on behalf of AstraZeneca and Akebia.
A version of this article first appeared on Medscape.com.