After a long and expensive clinical journey, Relypsa ($RLYP) won FDA approval to commercialize patiromer–to be sold as Veltassa–for hyperkalemia. And then the biotech promptly ran straight into a brick wall of negative reactions to the restrictive label that came with the regulatory OK.
By early morning trading hours Relypsa’s stock was down 30% as investors absorbed a bitter series of critical label reviews from top Wall Street analysts. The drug approval came with a block-box warning noting that the drug can only be taken 6 hours apart from other Veltassa doses or other oral drugs, due to the way this therapy binds to other treatments, cutting absorption and reducing the treatment effect.
While Veltassa is the first new drug for hyperkalemia to come along in decades, extracting dangerously high levels of potassium from the blood of patients being treated for chronic kidney disease, ZS Pharma’s ZS-9 is coming right up behind it. And analysts at JP Morgan, Morgan Stanley and others say the label on Veltassa is likely to pave the way toward making ZS-9 the superior drug on the market.
“This is likely to limit the demand for Veltassa, especially if ZS Pharma’s competing drug ZS-9 is approved without a black box warning or similarly cumbersome dosing protocol,” noted Morgan Stanley. “Given Veltassa’s restrictive label, we believe ZS-9 is likely to emerge as the differentiated, best-in-class potassium binder, a significant commercial advantage.”
Relypsa quickly found itself defending against the negative reaction. In an unusual response, the company claimed that the FDA had erred in its statement on the approval.
The FDA’s remark that “The use of Veltassa is not appropriate for rapid correction of severe hyperkalemia because lowering of serum potassium may take hours to days” is wrong, says the company. “What it does advise,” the company adds, “is that ‘Veltassa should not be used as an emergency treatment for life-threatening hyperkalemia because of its delayed onset of action.'”
“It’s not accurate to say the onset of action takes days,” notes a spokesperson for the company. “The label specifies the onset of action is 7 hours (section 12.2). The statement that is included in the label is intended to advise doctors that Veltassa should not replace standard emergency treatment for life-threatening hyperkalemia, such as intravenous insulin and glucose which act within minutes and are considered first-line agents in emergency situations; rather Veltassa can be used as an adjunct to emergency treatment to remove excess potassium.”
“We believe the FDA took a cautious approach with the label because of the number of people who might take this medicine,” CEO John Orwin told FierceBiotech in a prepared statement. “However, based on our market research and feedback from KOLs, it is our understanding that doctors believe Veltassa is an important new medicine that will help them manage a condition they currently find a challenge and worry about, and they will find this dose separation manageable.
“Most of the other medicines CKD and heart failure patients are taking are once- or twice-a-day in the morning and/or evening, and doctors advise us that Veltassa can be taken at lunch,” he added. “We will have results from our human drug-drug interaction studies early next year and, if appropriate, we plan to discuss a potential label update with the FDA.”
Redwood City, CA-based Relypsa and Sanofi ($SNY), which has co-promotion rights, were already facing some stiff headwinds on this drug. The old standards of care, including Kayexalate, may have problems with certain side effects, but with payers up in arms over the cost of new drugs, it may be hard to carve away market share from cheaper mainstays.
ZS Pharma ($ZSPH) is looking at a May 26, 2016, PDUFA date for ZS-9, a drug that has inspired some preliminary interest from Actelion in a takeover bid.
October 22, 2015 | By John Carroll