Cytokinetics stock reversed higher Tuesday after safety worries clouded promising study results for its Bristol Myers Squibb-rivaling treatment for a heart disease.
The company tested its drug, aficamten, in patients with obstructive hypertrophic cardiomyopathy, or HCM. In this condition, a genetic mutation causes the heart ventricles to thicken. This makes it difficult for the heart to pump blood — causing shortness of breath, chest pain and fainting during exercise.
After 24 weeks, patients who received aficamten had a significantly improved exercise capacity vs. the placebo group. Patients also showed improvements in 10 secondary goals of the study.
Aficamten works by reducing excessive contractility in the heart. But it can do that job too well — meaning the heart doesn't pump enough blood. That occurred in a handful of patients, though none dropped out of the study. Still, aficamten could face a Risk Evaluation and Mitigation Strategy, a Food and Drug Administration program to reduce the risks of certain drugs. The REMS on Bristol's rival drug, Camzyos, has limited its uptake.
Needham analyst Serge Belanger remained bullish on Cytokinetics' chances, however.
"We believe these additional Sequoia trial results further establish aficamten as the best-in-class and future standard of care for HCM," he said in a report. "The data will likely prompt more questions regarding the potential for a lesser REMS that may not be fully answered until expected FDA approval in mid-2025."
On today's stock market, Cytokinetics stock rose 3%, closing tat 49.38. On Monday, shares tumbled 6.8%, closing at 57.89. Shares have mostly traded below their 50-day moving average since late February, MarketSurge shows.
Shares initially rocketed 82.5% on Dec. 27 when Cytokinetics announced the top-line results of the Sequoia study. On Jan. 8, Cytokinetics shares jumped another 15% to a record high at 110.25 on takeover rumors. But the biotech stock has since pulled back almost 44% from that point.
Cytokinetics Stock: Rivaling Bristol Myers
Cytokinetics Chief Executive Robert Blum called the results of the Sequoia study "pristine."
"The consistency and the robustness of these results, we think, are very compelling," he told Investor's Business Daily. "Having been involved in this business for a long time, I can't remember another occasion where I've been able to be associated with such a pristine data set across every one of the endpoints. That's a very rare privilege."
Aficamten works by blocking an enzyme called myosin. It uses the same mechanism as Bristol Myers' Camzyos. But, Blum says, aficamten could be a safer version than Camzyos.
After 24 weeks, patients who received aficamten in the Sequoia study had a seven-point improvement in symptoms on the 100-point Kansas City Cardiomyopathy Questionnaire. The questionnaire assesses a patient's quality of life. On another measurement of heart failure symptoms, 34% of aficamten recipients improved by at least one class. There are four classes of heart failure.
Further, patients who received aficamten spent 78 fewer days eligible for septal reduction therapy, or SRT. Doctors recommend SRT for patients with hypertrophic cardiomyopathy when a medicine fails to control heart-failure symptoms. The aficamten treatment group also had an 80% reduction in a biomarker of cardiac wall stress compared with the placebo group.
Cytokinetics is now planning to ask the FDA and the European Medicines Agency to approve aficamten in the third and fourth quarters, respectively. The company is aiming for a mid-2025 launch.
Differentiating From Camzyos
Analysts following Cytokinetics stock say differentiating from Bristol Myers' Camzyos will be key for aficamten's success.
Aficamten has a shorter half-life than its counterpart, meaning it takes less time for the body to filter out the medicine. This allows doctors to increase the dosage faster, allowing patients to experience the drug's benefits more rapidly.
But there is a worry that myosin inhibitors can do their job too well — in other words, over-suppressing cardiac function. This would cause heart failure and is the reason why Camzyos is associated with a REMS program. In Cytokinetics' study, laboratory tests suggest five patients on aficamten experienced this side effect. Researchers at study sites say seven patients had this side effect.
But "there were no dose-interruptions and none of the patients experienced heart failure," Needham's Belanger said. He has a buy rating and 108 price target on Cytokinetics stock.
Blum estimates just 5% of patients with obstructive HCM are taking Camzyos due to the risks. But a potential aficamten launch could expand the market for both drugs, he said.
Notably, in the Sequoia study, none of the aficamten recipients had to interrupt or stop treatment due to left ventricular ejection fraction, or LVEF. This potential side effect signals the heart muscle isn't pumping enough blood. Blum noted there were a few patients who need smaller doses.
Other Competitors Are Coming
But Cytokinetics isn't the only biotech company angling for Bristol Myers' Camzyos market. Leerink Partners analyst Joseph Schwartz notes Edgewise Therapeutics, Tenaya Therapeutics, Lexicon Pharmaceuticals and others are entering the HCM ring.
As of Dec. 31, there were only about 4,500 patients taking Camzyos in the U.S., he said in a recent report. That's out of a potential market of 200,000 to 250,000 people with HCM in the country.
Camzyos sales are growing rapidly, but remain far from their potential. In the first quarter, Camzyos sales catapulted 190% to $84 million, but lagged views for $100.2 million, according to FactSet.
The drug's "onerous REMS is widely accepted among cardiologists as the limiting factor of uptake," he said. "Our base-case assumption is aficamten will likely receive a REMS, though it could be less restrictive vs. that of (Camzyos)."
Fellow Leerink analyst Roanna Ruiz has an outperform rating on Cytokinetics stock.
Follow Allison Gatlin on X, the platform formerly known as Twitter, at @IBD_AGatlin.
