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This morning shares of clinical stage biopharmaceutical company MyoKardia (MYOK 31.25, +14.10 +82.2%) are on fire after announcing topline results in its Phase 2 PIONEER-HCM Study of Mavacamten (Formerly MYK-461) in symptomatic, obstructive hypertrophic cardiomyopathy and announcing Q2 results. Since IPO-ing at $10 back in October of 2015, shares have surged about 20 points largely owing to the August-to-date 96.8% advance.
Firstly, the company announced positive topline data from the first patient cohort of its Phase 2 PIONEER-HCM study of mavacamten in symptomatic, obstructive hypertrophic cardiomyopathy (oHCM) patients.
This cohort met the primary endpoint of change in post-exercise peak left ventricular outflow tract (LVOT) gradient from baseline to week 12 as well as key secondary endpoints, including peak oxygen consumption (peak VO2).
Based on these results and subject to discussions in the coming months with the U.S. Food and Drug Administration (FDA), MyoKardia is planning for its next study, EXPLORER-HCM, to be a pivotal study. EXPLORER-HCM is expected to initiate by the end of this year.
Per the study, in the first patient cohort of PIONEER-HCM, 11 patients enrolled and 10 completed the study. A statistically significant improvement was observed in the primary endpoint, change in post-exercise peak LVOT gradient from baseline to week 12 (p=0.002). After 12 weeks of treatment, all 10 subjects (100%) achieved a reduction in post-exercise peak LVOT gradient from a baseline mean of 125 mmHg. In eight of the 10 subjects, the post-exercise peak LVOT gradient was reduced below the diagnostic threshold for oHCM (= 30 mmHg), with the other two patients’ measurements below 50 mmHg. Clinically meaningful improvements (= 30 mmHg) in resting LVOT gradient were observed as early as week 2 in nine out of 10 subjects, providing the rationale for the addition of a second, low-dose cohort to the PIONEER study. Additionally, clinically and statistically significant improvements were observed in peak VO2 (p=0.004).
Mavacamten was generally well-tolerated. One patient with a history of paroxysmal atrial fibrillation experienced a serious adverse event. In order to participate in the study, this patient had discontinued background beta blocker and disopyramide therapy, both of which are indicated for the management of atrial fibrillation. During the study, the patient experienced a recurrent episode of atrial fibrillation and was cardioverted. The patient had another episode of atrial fibrillation and was hospitalized and successfully treated with anti-arrhythmic therapy. The patient elected to stop study drug at week 4. All other adverse events (AEs) were mild to moderate, and a majority of the AEs were deemed to be unrelated to study drug.
In the coming months, the company intends to discuss the mavacamten clinical development plan in an End-of-Phase 2 meeting with the FDA and seek feedback on the potential for EXPLORER-HCM, its next study of mavacamten in symptomatic oHCM, to be a pivotal study with peak VO2 as the primary endpoint. The key inclusion and exclusion criteria for EXPLORER-HCM are anticipated to be similar to those for PIONEER-HCM, and the company expects to enroll between 200 and 250 patients in EXPLORER-HCM. MYOK also expects to initiate EXPLORER-HCM before the end of this year.
The company also announced today that the second, low-dose patient cohort in PIONEER-HCM has completed enrollment. MYOK expects to release topline data from this second patient cohort in the first quarter of 2018.
MYOK also announced Q2 results this morning. The loss per share of $0.41 was worse than the Street was expecting, and revenue growth of 60.0% to $5.6 million was not enough to satisfy market expectations. However, it appears that investors are focusing more on the pipeline news, and less on the quarterly print.
Given the relatively low short interest percentage of about 2.9% on MYOK (about 0.89 million shares sold short versus shares outstanding of about 31.5 million), it seems to be the data that’s driving the surge for MYOK today. Likely, there weren’t many bears trying to cover the stock on today’s surge, yet the move is a notable one as MYOK shares have not jumped this high on a percentage basis in the entire life of the stock (about two years). The trial results should bode well for the upcoming EXPLORER study, so look for that before the end of the year.
