Promedior, Plowing Ahead in Myelofibrosis, Sees Hope in Small Study

5/30/14Follow @benthefidler

[Updated 6/2/2014. See below.] Myelofibrosis, a rare and potentially fatal type of leukemia, isn’t an easy disease to treat. The only drug that’s been approved by the FDA approval to treat it, Incyte’s (NASDAQ: INCY) ruxolitinib (Jakafi), attacks the symptoms rather than the cause, and often leaves patients needing blood transfusions.

Several companies are trying to develop treatments that either top Incyte’s drug or work with it—among them a startup called Promedior, which is trying to find out if its drug prospect can do what ruxolitinib can’t. And while there is a long way to go, the Lexington, MA-based company is taking a small step in that direction today.

Promedior today is giving a glimpse at the interim top-line results of a Phase 2 study of its lead drug, PRM-151, in myelofibrosis. These data are early: Promedior is only reporting numbers from a group of 18 patients who completed 24 weeks of treatment on its drug. But Promedior believes it’s seen enough to move PRM-151 into further testing. That’s because 7 of the patients had a meaningful improvement in a variety of myelofibrosis symptoms; 5 of them had a clinically meaningful reduction in the scarring of their bone marrow; and a “number” of them saw their levels of healthy blood cells and platelets improve while on treatment, according to CEO Suzanne Bruhn (pictured above).

“Patients who get anemic end up having to get a lot of blood transfusions, and that becomes a big part of their life,” she says. “So if we can stabilize things like hemoglobin, we might be able to get people off of their transfusions, and become transfusion-independent at some point.”

These are, of course, small signals. Promedior has many questions to answer, much more proof to accrue, and is just one of several companies—including Gilead Sciences (NASDAQ: GILD), Cell Therapeutics (NASDAQ: CTIC), and more—pursuing new treatments for myelofibrosis. But while many of those companies are focused on a similar approach—targeting the janus kinase, or JAK family of enzymes—Promedior is banking on a different approach to make it stand out.

Myelofibrosis occurs when the bone marrow starts producing abnormal stem cells that grow and divide too quickly, taking over the marrow and scarring the tissue. The bone marrow then isn’t able to produce blood cells, triggering anemia. Worse, the bone marrow’s job is taken up by the spleen, which balloons in size, causing pain. Ultimately, the disease can lead to death. About 18,000 people in the U.S. are diagnosed with myelofibrosis each year.

Ruxolitinib became the first drug approved to treat myelofibrosis in November 2011. It’s a pill that blocks the activity of enzymes known as JAK2 and JAK1, which are involved in signaling pathways that help the abnormal stem cells grow. The drug isn’t a cure, however. Ruxolitinib was approved based on its ability to alleviate various symptoms of myelofibrosis, such as reducing spleen size, and easing abdominal pain. It doesn’t halt, or reverse the bone marrow scarring that’s already taken place. Plus, because it impacts both healthy and mutated forms of JAK2 and JAK1, ruxolitinib is often associated with exacerbating the low platelet and blood cell counts that patients may already have.

Clearly, there is room for improvement, which is why so many other drugmakers are in on the race. Gilead, for instance, paid more than $500 million for YM Biosciences three years ago for a JAK-inhibiting myelofibrosis drug that showed signs of possibly reversing patients’ anemia.  AstraZeneca and Cell Therapeutics are also among the companies that are developing variations of JAK inhibitors that, as Bruhn says, are trying to “get a little more benefit and a little less risk.”

So if Promedior can show that its drug can both impact bone marrow scarring, and reduce the anemia threat, it can enter the myelofibrosis discussion. Geron (NASDAQ: GERN), for instance, skyrocketed when its drug candidate, imetelstat, showed some ability to reverse fibrosis in a small trial—only to be pummeled by Wall Street after serious safety signals cropped up, leading to a partial clinical hold from the FDA.

Promedior thinks it has a shot to succeed because of its drug’s mechanism of action. PRM-151 is based on a … Next Page »

Ben Fidler is Xconomy's Deputy Biotechnology Editor. You can e-mail him at bfidler@xconomy.com Follow @benthefidler

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