By Mackenzie Tatananni
A confluence of safety concerns and underwhelming clinical data sent Erasca stock into a historic tailspin on Tuesday. A legal threat from a competitor was proving to be the least of the company's problems.
Erasca late Monday reported positive Phase 1 trial results for ERAS-0015, a therapeutic drug candidate tailored to patients with lung and pancreatic cancer. The preliminary data was accrued from ongoing dose escalation trials in the U.S., as well as a trial in China.
Investors quickly drew parallels to daraxonrasib, the high-profile lead asset from Revolution Medicines. Daraxonrasib has been on the receiving end of a storm of media coverage following an endorsement from former Nebraska Sen. Ben Sasse.
Sasse, who was diagnosed with Stage 4 pancreatic cancer in December, has credited daraxonrasib with shrinking tumors and alleviating his pain along with morphine, touting it as a "miracle drug" in a recent interview. Regulators have yet to approve daraxonrasib for sale in the U.S., and the drug is only available through participation in authorized clinical trials.
Evercore ISI analyst Sean McCutcheon said in a Tuesday note that while early data for Erasca's treatment was promising, it failed to prove that ERAS-0015 was "clearly differentiated from daraxonrasib."
While ERAS-0015 may be more potent than Revolution's asset, "simply by observing the doses used...it is not clear from the results whether there is improvement to the profile of daraxonrasib on either efficacy or safety," McCutcheon wrote in a research note.
Erasca cratered 50%, putting the stock on pace for its largest single-day percentage drop on record, according to Dow Jones Market Data. Revolution stock advanced 8.8%.
Sentiment was further dampened by the death of a patient taking ERAS-0015. Evercore ISI analyst Jonathan Miller noted that the individual in question, a 66-year-old man, had been living with late-stage pancreatic ductal adenocarcinoma, the most aggressive form of pancreatic cancer.
Following a pneumonitis event, the patient opted to withdraw from supported care, at which point his symptoms worsened until the patient died.
Management was quick to calm the room on a Monday call with analysts after the data release, saying such an outcome was typical for the drug class. While a severe result "is always a problem," investors should consider the context of the patient withdrawing from care, Miller added.
Legal pressures also are mounting for Erasca in the race to develop a game-changing cancer drug. Last week, Revolution sent a letter to Erasca which alleged that ERAS-0015 was "substantially equivalent" to one of its patented treatments.
Revolution's patent, viewed by Barron's, covers the use of so-called Ras inhibitors to treat cancer. Ras inhibitors block a small protein that sits inside the cell membrane and acts as an on/off switch, setting off a signaling cascade that can make a cell grow or divide. Revolution is developing a portfolio of these medications led by daraxonrasib, which is positioned to become the company's first commercial product.
Revolution alleged that a third party had misappropriated its trade secrets for an ERAS-0015 patent and that Erasca, as the licensee, was legally liable. Moreover, the company accused Erasca of drawing improper comparisons between preclinical data for ERAS-0015 and daraxonrasib.
Revolution is demanding Erasca wind down production and halt U.S. sales of ERAS-0015. The stakes are high: neither Revolution nor Erasca has yet to commercialize a product, and achieving a first-to-market launch would be a critical milestone.
Erasca has vowed to fight Revolution's claims "vigorously," adding that they were "without merit."
Write to Mackenzie Tatananni at mackenzie.tatananni@barrons.com
This content was created by Barron's, which is operated by Dow Jones & Co. Barron's is published independently from Dow Jones Newswires and The Wall Street Journal.
(END) Dow Jones Newswires
April 28, 2026 12:29 ET (16:29 GMT)
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