Milestone Pharmaceuticals Inc.'s (MIST:NASDAQ) upcoming March 27, 2025 PDUFA (Prescription Drug User Fee Act) date would be "the start of a multibillion-dollar opportunity," with approval of Cardamyst (etripamil), an investigative at-home intranasal treatment for paroxysmal supraventricular tachycardia (PSVT), reported H.C. Wainwright & Co. Analyst Patrick Trucchio in a March 17 research note.
"If approved, we estimate peak annual revenues of $500 million ($500M)-plus for Cardamyst in PSVT," Trucchio wrote.
1,052% Implied Return
H.C. Wainwright & Co. has a $25 per share price target on the Canadian biopharma, now trading at about $2.17 per share, noted Trucchio. Thus, the target implies a potential return of 1,052%.
Milestone remains a Buy.
Lower Patient, Healthcare Burden
Trucchio explained what PSVT is and how Cardamyst works to stop instances of it. A chronic cardiac arrhythmia, PSVT is characterized by the unpredictable and sudden onset of rapid heart rates, often above 150 beats per minute (150 bpm). It can cause palpitations, chest discomfort, dizziness and fainting. An underappreciated, unmet medical need, PSVT affects about 2 million (2M) people in the U.S. With about 650,000–1,000,000 (650K–1M) patients seeking treatment each year, the financial burden on the healthcare system is an estimated $5 billion ($5B) annually.
Cardamyst is a fast-acting nasal spray that blocks calcium from entering the atrioventricular node, which in turn slows conduction and returns the heart rate to normal sinus rhythm, thereby stopping PSVT episodes. It is designed so that patients may dose themselves when symptoms come on, allowing for treatment any time, anywhere.
The current standard of care for PSVT includes intravenous therapies like adenosine, calcium channel blockers and beta blockers, requiring administration in an emergency department (ED) or hospital setting, and less often, cardiac catheter ablation.
"If approved, Cardamyst would be the first self-administered, rapid-acting therapy designed to terminate PSVT episodes outside a medical setting, offering patients a novel approach to managing their condition," Trucchio noted.
Cardamyst also could lower the cost to the healthcare system by reducing ED visits by and hospitalizations of PSVT patients.
Preparing for Commercialization
Trucchio pointed out that Milestone has been preparing for and continues to prepare for a commercial launch of Cardamyst. If the drug is approved, the biopharma should receive a $75M synthetic royalty payment under an existing agreement with RTW Investments, an investment firm established in March 2023. The biopharma secured the payment to fund at least four quarters (into mid-2026) of a commercial launch of Cardamyst for PSVT in the U.S. Once the new drug hits the market, Milestone intends to target community-based cardiologists and electrophysiologists initially, as they manage most PSVT patients.
Market research shows that cardiologists expect to prescribe Cardamyst to about 50% of their PSVT patients, translating to a potential target population of 500–800K patients in peak years. Further, patient use patterns in clinical trials showed Cardamyst likely will be used for a median of three to five episodes a year, equating to possible peak demand of 2.5–4M episodes treated annually.
"With $75M in expected milestone payments upon approval and a commercial launch targeted for mid-2025, we see significant upside potential in shares of MIST, which we continue to view as undervalued relative to the long-term opportunity," Trucchio commented.
Pursuing Second Indication
The analyst highlighted that a Cardamyst approval on March 27 also would open the door to a "significantly larger opportunity in atrial fibrillation with rapid ventricular rate (AFib-RVR)," as Milestone is advancing the same self-administered, intranasal treatment in this indication, an area of significant unmet need, as well. With AFib-RVR, patients have acute episodes of high ventricular rates causing symptoms such as palpitations, shortness of breath, chest pain, lightheadedness and severe fatigue. Nearly 1.1 ED admissions annually are due to atrial fibrillation symptoms, and of these about 60% are attributed to AFib-RVR. Available treatment options are limited.
There already are supportive Phase 2 data, from the ReVeRA study that evaluated Cardamyst in patients presenting urgently with AFib-RVR. Specifically, the trial's primary endpoint was met with high statistical significance (p<0.0001); ventricular rates were reduced by an average of 29.91 bpm compared to placebo. Rate control lasted at least 150 minutes, and symptom relief was shown to be statistically significant.
Phase 3 Trial Greenlighted
Milestone has U.S. Food and Drug Administration approval to conduct a Phase 3 clinical trial of Cardamyst in AFib-RVR, reported Trucchio. The agency indicated that such a trial may be enough for approval via the supplemental new drug application pathway, in light of the extensive existing safety data resulting from the PSVT clinical program. About 150 patients will be enrolled, each with at least one verified episode of AFib-RVR.
Trucchio wrote that with AFib-RVR, the projected addressable target market is 3–4M U.S. patients by 2030, according to H.C. Wainwright estimates. Given that AFib-RVR affects a broader population having more frequent symptoms than PSVT, the revenue potential for Cardamyst in AFib-RVR, if approved, could exceed $1B. In both indications, the total potential is $2B.
Events Worth Watching
The analyst presented three key upcoming events for Milestone. They are the PDUFA outcome on Cardamyst in PSVT on March 27, 2025. Another is commercial rollout of the drug in the middle of this year assuming its gets FDA approval.
The third, related to the AFib-RVR program, is patient enrollment for the Phase 3 trial, slated to start in Q2/25.
These near-term catalysts "can drive robust value creation for shareholders" in the near term, wrote Trucchio.
Company Data
Milestone has 53.3M shares outstanding. Its market cap is $116M. Its 52-week range is $1.12–2.75 per share.
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