It’s a Go for Thoratec’s U.S. HeartMate III Trial

Marie Thibault

FDA has granted Thoratec Corp. permission to enlarge its pivotal trial for the next-generation HeartMate III left ventricular assist system (LVAS). This gives the company the ability to enroll a 1028-patient trial at 60 sites around the United States. The agency gave the go-ahead after evaluating safety data from the first ten patients enrolled as part of a conditional approval phase.

The Pleasanton, CA-based Thoratec is one of two major LVAS makers selling in the United States. LVAS are implanted in very sick heart failure patients, sometimes as a holdover while a patient waits for an eligible heart transplant. HeartMate III is the next iteration of the company's current commercial device, the HeartMate II, and is smaller, with a fully magnetically-levitated design.

The HeartMate III trial design is unique in two ways—first, it included a safety phase for the first 30 patients enrolled, and second, it allows for assessment of two indications in a single trial. The U.S. trial began enrolling in September under conditional approval for 30 patients at five sites. With this week's announcement, FDA has signaled that it is comfortable with the safety results seen so far. Now, with full approval, 60 hospitals can participate in the trial.

There are two major indications for LVAS use: bridge-to-transplant (BTT) and destination therapy (DT). Historically, companies have been required to run separate trials for each indication. Because DT patients are likely going to be living with the device longer than patients who are expecting to receive a heart transplant, DT trialshttp://www.mddionline.com/node/12436/edit require a longer follow-up. In practical terms, this has meant that prior commercial LVAS devices often receive BTT approval years before DT approval. This has frustrated patients and physicians, because the line between who is a transplant candidate and who should be a DT patient is sometimes blurred.

The HeartMate III U.S. pivotal trial design addresses this by evaluating the first 294 patients randomized in the trial out to a six month endpoint for a BTT indication. To study the DT indication, the first 366 randomized patients will be followed for two years. There is also room for approximately 600 more patients to evaluate superiority of pre-specified secondary endpoints. The primary endpoint is survival free of device replacement and debilitating stroke.

This week's announcement keeps Thoratec right on schedule, if not slightly ahead. On the company's last earnings call, chief executive officer D. Keith Grossman said he expected the broad enrollment phase to begin during the second quarter.

There has been a high level of clinical interest around the HeartMate III device. A CE Mark trial for the device was started in June 2014 and had already wrapped up enrollment of 50 patients by December. Six-month follow-up on those patients is being gathered now and CE Mark approval is anticipated in late 2015.

So far for Thoratec, 2015 seems to be an improvement on 2014. Last year, MD+DI named the company one of the “Medtech Losers of 2014” after a Class I recall, tough stock performance, and concerns about ability to hold market share. Thoratec’s stock price is up 28% from the end of 2014.

Marie Thibault is the associate editor at MD+DI. Reach her at [email protected] and on Twitter @medtechmarie. 

[Image courtesy of THORATEC CORP.]