 |
| HVAD pump--Courtesy of HeartWare International |
HeartWare ($HTWR) touted clinical trial data showing that its Ventricular Assist device met its primary endpoint of stroke-free survival at two years, but concerns about the stroke risk of patients on the device for heart failure persisted, sending the stock tumbling more than 6% in early trading on the news.
The company seeks to expand the indication of the HeartWare Ventricular Assist device (HVAD) to include use as a long-term "destination therapy" for patients who are ineligible for a heart transplant. It was FDA-approved for short-term use as a bridge to heart transplantation in 2012.
The 446-patient ENDURANCE trial compared the HVAD to Thoratec's ($THOR) HeartMate II, which already has the FDA's blessing for use as a destination therapy. HVAD demonstrated noninferiority to the competitor as a long-term solution when judged by the primary endpoint--55% of HVAD patients experience stroke free survival at two years after implantation of the device, compared to 57.4% on the HeartMate II.
The bad news is that the stroke rate among patients on the device was 31.1%, compared to 12.7% among trial patients implanted with Thoratec's HeartMate II.
"THOR could undoubtedly attempt to gain some ground vs. HTWR by pointing to a nearly 3x higher stroke rate in this initial trial cohort. This data will clearly create some noise in the market and could give THOR at least a temporary leg up, in our view, particularly as HeartMate III enrolls its U.S. pivotal study with the safety phase already underway," wrote Leerink Equity analysts Danielle Antalffy and Puneet Souda in an analyst note.
But the analysts pointed to several details showing that upon closer examination, the data don't seem so damning, and still believe the HVAD will get FDA approval as a destination therapy in 2016 or early 2017.
"In patients who did undergo blood pressure management, (co-principal investigator) Dr. (Francis) Pagani presented a 34% reduction in ischemic stroke and a 44% reduction in hemorrhagic stroke. In addition, at HTWR's ongoing 'deep dive' meeting for both physicians and investors, we also learned that stroke severity was much greater in HeartMate II patients--meaning that HeartMate II patients who did have a stroke had a significantly worse event," they wrote.
Due to the data among patients who did receive blood pressure management, Antalffy and Souda expect better results in HeartWare's supplementary trial of a secondary cohort of patients who are required to manage blood pressure.
They also pointed to European registry data (where the device is already approved for long-term use) showing that real-world HVAD patients experience stroke at rate of 14%, far lower than that experienced in ENDURANCE.
"We're inclined to think--assuming ENDURANCE 2 does see a reduction in stroke--the totality of data across both the U.S. and Europe will be sufficient to secure approval in the much-larger $2.5B+ DT (destination therapy) market," the Leerink analysts conclude.
HeartWare officials were hounded by Wall Street analysts about the stroke-risk data from ENDURANCE during a question-and-answer session at the International Society for Heart and Lung Transplantation Meeting in Nice, France. The officials stressed that the data shows that HVAD patients who suffered a stroke were less likely to die than stroke sufferers who used the HeartMate II .
FDA approval of the expanded indication will hinge on the results from ENDURANCE 2, in which patients will be required to manage their blood pressure. Co-principal investigator Dr. Francis Pagani told the analysts that the importance of managing blood pressure to lower the risk of stroke is the "takeaway message" from the recently completed trial.
- read the release
- read the Leerink analysis
- listen to the company presentation (reg. req.)