Cytokinetics Says MYKORZO Launch Tops Expectations as HCM Data Draws Praise

Key Points

• MYKORZO’s launch is outperforming expectations, with Cytokinetics saying early prescriptions, reimbursements, and total demand are tracking above internal goals. The company said most first-quarter patients were treatment-naive, suggesting the drug is expanding into new patients rather than just switching existing therapy users.
• Physician feedback on the label, REMS, and HCM data has been positive, especially the broad symptomatic HCM indication, the two-to-eight-week echo monitoring window, and no REMS drug-interaction monitoring requirement. Doctors are also citing rapid symptom relief and gradient reduction as key differentiators.
• Recent ACACIA-HCM results could broaden the market opportunity, as the study in non-obstructive HCM met both primary endpoints and drew strong praise from clinicians. Cytokinetics believes the data may support future adoption, guideline inclusion, and a larger long-term opportunity beyond obstructive HCM.

Cytokinetics NASDAQ: CYTK executives said the commercial launch of MYKORZO is tracking ahead of internal expectations, while also highlighting positive physician feedback on the drug’s label, REMS program and recent clinical data in hypertrophic cardiomyopathy during a discussion hosted by RBC Capital Markets.

Gregory Renza, managing director and analyst at RBC Capital Markets, opened the discussion by asking about investor concerns around the REMS requirements and how the final label is shaping early commercialization. A Cytokinetics representative said the label and REMS were “as we expected,” citing what the company views as favorable elements, including a two-to-eight-week echocardiogram monitoring window, no drug-drug interaction monitoring requirement within the REMS program, and a broad indication for symptomatic hypertrophic cardiomyopathy without mention of New York Heart Association class.

The company said those features are resonating in practice and in physician pulse surveys conducted since launch. The representative said physicians are citing rapid symptom improvement, gradient reduction, and the safety and efficacy profile as differentiating factors.

Early launch trends and patient starts

Cytokinetics said its focus is primarily on new patients rather than switching stable patients from other therapies. The company estimates more than 100,000 symptomatic obstructive HCM patients are eligible for treatment, with “over 80% of the market still available.”

According to the company, more than 95% of patients started on MYKORZO in the first quarter were treatment-naive, while switches represented less than 5%. The company also said prescribing is occurring across physician segments, including doctors who had not previously prescribed a CMI.

The representative said the company’s launch aspiration was to perform “at or better” than the first-year launch of Bristol Myers Squibb’s CMI, and said Cytokinetics believes it is tracking above that benchmark. The company cited metrics such as reimbursed prescriptions that are paid, time to reimbursement, new-to-brand share and total prescriptions as exceeding expectations in the first quarter.

Renza also asked whether the REMS process had created friction for physicians or smaller practices. The company said the practical features of the REMS are receiving positive feedback, but acknowledged some early operational friction as offices used the REMS system. Cytokinetics said support staff access was expanded through an enhancement in late March or early April, and that functionality is moving closer to the company’s target.

On dosing, the company said most patients remain on 5 milligrams, though some are receiving 15 mg and 20 mg. The company said it is too early to draw firm conclusions on persistence, but its internal modeling assumes 70% to 80% of patients who start therapy remain on treatment after one year.

Payer access and European launch plans

Cytokinetics said it is working toward comparable payer access with the other approved CMIs. The company estimated the market is roughly 60% Medicare and 30% commercial. On Medicare, the company said it expects to reach parity with Bristol Myers Squibb during the second quarter and is currently close to 90% parity. On the commercial side, the company said it expects parity in the fourth quarter and is approaching 50% of commercial lives covered.

The company also discussed international expansion. It said MYKORZO is approved in the European Union and that filings have been made with Swissmedic and the U.K.’s Medicines and Healthcare products Regulatory Agency. Germany is expected to be the first European launch market, representing roughly 30% to 33% of the European revenue opportunity, according to the company.

The company said the next potential launches could include the U.K. and the Netherlands toward the fourth quarter, depending on reimbursement. It said European pricing is expected to be around 15% of the current U.S. price, reflecting the government payer and health technology assessment process.

Asked about Most-Favored-Nation policy concerns, the representative said Cytokinetics decided to move forward with Europe, citing patient access and the company’s view that a potential impact, if implemented as currently discussed, could be in the single digits on gross-to-net.

MAPLE-HCM and ACACIA-HCM data

The company said the MAPLE-HCM supplemental application does not introduce a new patient population but could support use of MYKORZO as monotherapy and expand penetration in obstructive HCM. The representative said the data could serve as a “call to action” for general cardiologists, particularly if incorporated into guidelines.

Daniel Jacoby, vice president of clinical research and executive medical director at Cytokinetics, discussed the ACACIA-HCM trial in non-obstructive HCM, which met both of its endpoints. Jacoby said early feedback from the company’s academic steering committee, key opinion leaders and heart failure specialists has been highly positive, with some using words such as “home run” and “transformative” to describe the results.

Jacoby said the significance comes from seeing benefit in both symptoms and exercise capacity in a heart failure population with no other available treatment. He said the peak VO2 difference and KCCQ results, supported by secondary endpoints such as NYHA class, NT-proBNP and measures of maximal and submaximal exercise capacity, indicate an important clinical benefit.

Jacoby also said the company will continue evaluating whether longer treatment duration deepens benefit, including through long-term extension data in FOREST-HCM and an MRI substudy in ACACIA-HCM that may provide more information on remodeling.

Market opportunity and pipeline updates

Cytokinetics said recent claims analysis suggests more than 400,000 diagnosed HCM patients, split roughly evenly between obstructive and non-obstructive disease. The company estimated about 120,000 symptomatic obstructive HCM patients and about 110,000 symptomatic non-obstructive HCM patients may be eligible for treatment.

The representative said non-obstructive HCM could become a major contributor to the MYKORZO opportunity if the drug is first to market and supported by ACACIA-HCM data, though both obstructive and non-obstructive HCM are expected to be meaningful.

Jacoby also provided brief pipeline updates. For CK-586, which he identified as ulacamten, Cytokinetics expects to complete enrollment in the first cohort by the end of the year. He said ACACIA-HCM supports the broader hypothesis that modulating hypercontractility in patients with heart failure related to diastolic dysfunction can improve symptoms and clinical findings, which may inform the company’s HFpEF program.

On omecamtiv, Jacoby said enrollment is progressing and the company is looking to complete enrollment in the coming year, with results expected in 2028 or 2029.

About Cytokinetics NASDAQ: CYTK

Cytokinetics, Inc is a late‐stage biopharmaceutical company focused on the discovery and development of novel small‐molecule therapeutics that modulate muscle function. Founded in 1998 and headquartered in South San Francisco, California, the company applies its proprietary insights in muscle biology to address diseases characterized by impaired muscle performance. Its research spans both cardiac and skeletal muscle targets, aiming to deliver innovative medicines for conditions with significant unmet medical need.

The company's most advanced program, omecamtiv mecarbil, is being evaluated for the treatment of heart failure by enhancing cardiac muscle contractility.

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