There are a number of implications stemming from the decision by Affymax and Takeda to voluntarily withdraw the anaemia treatment Omontys from the US market over the weekend.
Insight, Analysis & Opinion
The position of Affymax looks precarious. Market reaction on Monday morning suggests that Omontys is unlikely to return to the market or have much of a commercial future if it does; Affymax shares were down approximately 85 percent when markets opened, reflecting both damage to the credibility of the Omontys franchise and its status as Affymax's only marketed product. With a lack of additional pipeline products in development, it was no surprise to hear analysts pushing management on the issue of the company's cash levels during a conference call to discuss the withdrawal.
If Omontys is to return to the market, the key challenge will be persuading nephrologists to use the product given the entrenchment of Amgen's Epogen franchise, noted analysts at Baird, also emphasising the surprise nature of this announcement given their very recent conversations with Affymax management (in mid-February).
Analysis by Baird analysts suggests that Omontys is associated with a higher incidence of death than Epogen and higher rates of hypersensitivity and anaphylaxis. In a market where drug safety vigilance continues to increase, their conclusions make for interesting reading: "With no published reports for Omontys in the current FDA AERS data and the prior information released from Affymax and Fresenius, it's hard to envision how this could have been prognosticated. That being said, our back of the envelope analysis paints a different view for Omontys than we had just a few days ago and ultimately highlights the limitations of clinical trials relative to real-world experience."
International Investment and Strategy analyst Mark Schoenebaum concurred in a note to investors, highlighting the high level of scrutiny that an FDA AdCom exerted on Omontys. Only its use in around 25,000 patients in the ‘real world’ has ‘exposed’ the safety profile of the drug, he adds.
Broader implications could occur in the form of a more cautious approach by the FDA towards biosimilar approvals, argues Scott Gottlieb in an article for Forbes. Given the FDA's already less adventurous stance towards biosimilars (stemming from the inability to fully characterise biologics), the Omontys development could make authorities more wary says Gottlieb.
Furthering the conclusions reached by analysts at Baird, Gottlieb notes that despite the FDA's "years of experience with biological agents that simulate red blood cell production, the inability to ferret out the risks with Omontys is likely to underscore how hard this science remains." Gottlieb's postulations have triggered some debate, and he himself notes that Omontys was a different molecule to either Epogen or Aranesp.
Nevertheless, the very fact that Omontys was a novel branded drug with a full Phase III data set should not diminish the implications this withdrawal could have on the FDA’s thinking. Schoenebaum notes that biosimilars may be submitted for regulatory approval with "less human safety data than Affymax had generated for Omontys." Furthermore, he says that although biosimilars will be approved and launched in the future, the Omontys withdrawal represents further incremental evidence to suggest that uptake of such products will be slow. "Doctors will (or at least should) wait for proper real-world exposure data before prescribing," he adds.