Milestone Extends Its Cash Runway as CARDAMYST’s Early Sales Lag Launch Costs

Milestone Pharmaceuticals is extending the time it has to build sales of its first medicine and complete a pivotal trial in a second heart-rhythm condition. The company plans to reduce operating expenses by approximately 30%, while preserving the sales force promoting CARDAMYST, a nasal spray launched in the United States this year. Management expects cash to fund operating expenses and capital spending into late 2028, more than a year beyond its prior estimate.

The November 13 update comes at an early stage of commercialization. Third-quarter CARDAMYST revenue was $963,000, while selling, general and administrative expense was $24.2 million. Prescriptions and insurance coverage have increased, but converting that progress into revenue sufficient to support the launch will take time. A separate $2 million licensing milestone also made total revenue appear substantially larger than product sales.

A treatment patients can carry

CARDAMYST contains etripamil, a calcium channel blocker. The FDA approved it for adults experiencing symptomatic episodes of paroxysmal supraventricular tachycardia, or PSVT, in which the heart suddenly begins beating abnormally fast. Episodes can cause palpitations, dizziness, chest discomfort and shortness of breath. Patients may use the prescribed nasal spray themselves when an episode occurs.

That route of administration addresses a practical problem. Drugs used to stop episodes include intravenous therapies administered under medical supervision, often in an emergency department. Catheter ablation, a procedure intended to interrupt the electrical pathway responsible for an arrhythmia, is another option for appropriate patients. CARDAMYST gives physicians a treatment patients can have available outside a medical facility; the appropriate choice depends on the individual patient's condition and care plan.

In the FDA prescribing information, the RAPID study's primary analysis included 184 patients with confirmed PSVT episodes. Estimated conversion to normal sinus rhythm within 30 minutes was 64% with CARDAMYST and 31% with placebo. These were Kaplan–Meier estimates, which account for the timing of events. The label also warns about fainting risk; nasal discomfort and congestion were among the common adverse reactions.

Milestone estimates PSVT affects more than two million Americans and identifies roughly half of that diagnosed population as its immediate target market, based on disease burden and care-seeking. Those are company estimates, not a forecast of patients who will receive CARDAMYST. Diagnosis, physician choice, insurance restrictions and the frequency of episodes will influence the reachable population.

Prescriptions are growing from a small base

The medicine became available through U.S. retail pharmacies in January, with the sales force deployed in February. In its third-quarter update, Milestone said approximately 3,400 prescriptions had been written by around 1,600 unique prescribers since launch. Commercial insurance coverage had risen to roughly two-thirds of covered lives, from about half in August. Coverage describes the insured population with access under a plan and does not establish how many patients receive or fill a prescription.

There is a reporting inconsistency in the prescription measure. The earnings release describes the approximately 3,400 prescriptions as written; the quarterly filing describes approximately the same number as filled. Until Milestone clarifies the relationship, the figure should not be used to calculate a prescription fill rate. Revenue is recognized when product is received by customers, including wholesalers, net of estimated discounts, rebates and other allowances; it is not a direct count of patient use.

Net product revenue increased 73% from the second quarter to $963,000 in the third. That growth indicates progress, although the absolute base remains small. The company's commercial opportunity depends on persuading more relevant specialists to prescribe, helping eligible patients obtain coverage and building repeat use when clinically appropriate.

A milestone changes the revenue mix

The 10-Q income statement separates U.S. product sales from a payment tied to regulatory approval in China. Everest Medicines acquired the Greater China rights to etripamil and the associated obligations from Milestone's earlier partner. The $2 million recognized in the third quarter followed China's approval for PSVT and should be assessed separately from ongoing U.S. sales.

The increase in selling, general and administrative costs reflects the company's transition to a commercial launch. Third-quarter product gross profit was approximately $638,000 before commercial and other expenses. The apparent product gross margin of about 66% is not a reliable long-term margin: Milestone expensed manufacturing costs before approval, leaving some early inventory with a zero-cost basis. Later units will carry more of their manufacturing cost.

The planned cost reductions are meaningful relative to current spending, but the company has not provided a detailed quarterly expense bridge. It expects to reduce its workforce by approximately 20%, with the reduction expected to finish in the first quarter of 2027. Maintaining the sales force preserves a route to physicians, while the loss of other commercial support and management capacity may affect execution. The size and timing of savings will become clearer in subsequent results.

Cash today and claims on future sales

At September 30, Milestone held $145.4 million in cash, cash equivalents and short-term investments, compared with $106.0 million at the end of 2025. The increase reflects financing as well as cash used by operations. During the first nine months of 2026, operating activities used $64.0 million, compared with $36.3 million in the same period of 2025.

The nine-month net loss was $80.5 million. Noncash interest and debt costs of approximately $11.0 million, share-based compensation of $4.0 million and other adjustments help explain the difference between the accounting loss and operating cash outflow. Changes in operating assets and liabilities also had a net positive effect, including higher payables and accruals that partly offset inventory and receivables increases.

Financing inflows included $75 million received in January from RTW Investments for a right to royalties on U.S. etripamil sales. Under the royalty agreement described in the filing, the initial rate is 7% of annual U.S. net sales up to $500 million, with lower rates on higher tiers. The initial rate can increase to 9.5% if specified sales thresholds are missed, and return to 7% when a subsequent threshold is met. The upfront cash therefore carries a claim on future sales.

Milestone also issued $50 million of 6% convertible senior notes in 2023. At September 30, accumulated paid-in-kind interest had increased principal by approximately $11.6 million; the carrying amount after unamortized discounts and costs was $60.2 million. A November amendment allows the company to elect to add interest to principal until maturity in 2029. That can conserve cash before the trial readout, while increasing the amount owed if the option is used.

A second indication has a different endpoint

Milestone is studying etripamil in atrial fibrillation with rapid ventricular rate, or AFib-RVR. In atrial fibrillation, the heart's upper chambers beat irregularly; a rapid ventricular rate means the lower chambers are also beating too quickly. The current PSVT approval does not cover this condition.

In a Phase 2 study, 56 patients were dosed after presenting urgently with AFib-RVR. Milestone reported that etripamil reduced ventricular rate by approximately 29.9 beats per minute relative to placebo on the study's primary measure. Those patients were treated in an urgent-care setting; the Phase 3 ReVeRA-301 study evaluates self-administration outside a monitored setting. Its primary endpoint compares the change from baseline to the lowest ventricular rate after treatment, with patient-reported symptom improvement as a key secondary endpoint.

The company has designed the study around approximately 150 treatment events from 150 patients and expects topline results in the second half of 2028. Management's revised runway extends into late 2028, placing the anticipated data and the end of its forecast funding period in the same broad window. Enrollment, the timing of qualifying episodes, spending and the commercial launch can all affect that alignment.

For investors, the next evidence is commercial: whether prescription growth and broader coverage translate into a sustained rise in net product revenue as spending falls. Over the longer term, the AFib-RVR results could expand etripamil's use if they support approval. The pace of the existing launch and the cost of reaching that readout will determine how much flexibility Milestone retains along the way.