FibroGen Plunges on Murky Data Clarification for CKD Drug Roxadustat

FibroGen remains unsuccessful in expressing confidence in risk profile of Roxadustat. (Smith Collection/Gado/Getty Images)

Shares of FibroGen were crashing this morning after the company unsuccessfully attempted to express confidence in the benefit/risk profile of its anemia drug, Roxadustat. This comes ahead of the U.S. Food and Drug Administration’s review of the company’s New Drug Application following a data clarification it made regarding its efficacy. 

After announcing Tuesday that the FDA tentatively scheduled a Cardiovascular and Renal Drug Advisory Committee to review roxadustat, San Francisco-based FibroGen sought to quell any investor concern by providing what it called “clarification of certain prior disclosures” of primary cardiovascular safety analyses from the roxadustat Phase III program that were submitted to the FDA in the NDA. FibroGen is developing roxadustat for the treatment of anemia of chronic kidney disease (CKD).

Enrique Conterno, chief executive officer of FibroGen, said the company became aware that primary cardiovascular safety analyses included post-hoc changes to the stratification factors. In the company’s announcement, Conterno said analysis of the data may show that roxadustat is not superior to another drug called epoetin-alfa in lowering the risk of cardiovascular events in some kidney disease patients. 

According to company data, the analyses with the pre-specified stratification factors result in higher hazard ratios and 95% confidence intervals. For MACE+ in dialysis and for MACE and MACE+ in incident dialysis, the 95% confidence intervals include 1.0. While these hazard ratios remain below 1.0, based on these analyses the company said it cannot conclude that roxadustat reduces the risk of (or is superior to) MACE+ in dialysis, and MACE and MACE+ in incident dialysis compared to epoetin-alfa.

FibroGen was quick to note that the additional analyses do not change its assessment that roxadustat is comparable to placebo in non-dialysis dependent patients and to epoetin-alfa in dialysis dependent patients using MACE to measure cardiovascular safety. Contera emphasized the company maintains its confidence in roxadustat’s benefit risk profile.

The company also said that there is no change in the underlying roxadustat data or to the efficacy analyses from the Phase III program. FibroGen added that it has begun a comprehensive internal review to ensure such issues do not occur in the future.

Roxadustat is the first in a new class of medicines, HIF-PH inhibitors that promote erythropoiesis, or red blood cell production, through increased endogenous production of erythropoietin. The medicine has already been approved in China, Japan and Chile for the treatment of anemia of CKD in adult patients on dialysis and not on dialysis.

FibroGen is also assessing Roxadustat for anemia associated with myelodysplastic syndromes and for chemotherapy-induced anemia. The company is working in collaboration with Astellas and AstraZeneca on the development and marketing of roxadustat.