Clinical Hold Turns out to be Serendipitous for Protagonist's PV Program

Protagonist Therapeutics announced updated promising data from its phase II Revive clinical trial, which is evaluating the safety and efficacy of rusfertide in patients with polycythemia vera (PV).

PV is considered a myeloproliferative neoplasm, which refers to a category of blood cancers where the patient’s bone marrow makes an overabundance of red blood cells, white blood cells and/or platelets.

The Revive study is ongoing and monitors 70 patients that are dependent on phlebotomy over the course of 18 months. Phlebotomy is standard blood taking with a goal of reducing the overabundance of cells circulating through the patient’s body.

The updated results demonstrate that, while being treated with rusfertide, patients no longer require therapeutic phlebotomy because they’ve become able to stabilize hematocrit levels on their own. The patients demonstrated hematocrit levels below 45%, which tells the study investigators that the blood volume has been reduced to levels much closer to normal. This response was seen shortly after patients began rusfertide treatment and is considered sustainable. Along with a stabilized blood volume, study participants demonstrated normalization of iron levels and an increased ability to concentrate.

In a serendipitous sequence of events, a clinical hold was placed on clinical studies for rusfertide in the fall of 2021. The hold was later lifted, but treatment had stopped for a short time. During this pause, the researchers were able to observe the effects of treatment stoppage. When patients were no longer receiving the treatment, hematocrit levels rose and they required therapeutic phlebotomy once again. After the hold was lifted, the majority of the previously enrolled patients continued to benefit from rusfertide treatment.

Dinesh V. Patel, Ph.D., president and CEO of Protagonist commented on the results.

"These highly promising new results continue to demonstrate the rapid therapeutic effect of rusfertide and its utility as an effective potential treatment across all categories of PV patients, independent of patient risk category, or concurrent therapy with other cytoreductive treatments including hydroxyurea, interferons or JAK inhibitors," he said. "Taken together, these data reaffirm our belief in the potential of rusfertide to provide a highly effective treatment option for patients with PV, providing an opportunity to fundamentally transform the management of this disease. Rusfertide continues to be the primary focus of our corporate resources and efforts, and we continue to explore the full therapeutic potential of rusfertide with a sharp focus on the execution of the recently initiated Phase 3 VERIFY study."

In June of last year, Protagonist celebrated receipt of a Breakthrough Designation for rusfertide from the U.S. Food and Drug Administration (FDA). The designation communicates the FDA’s recognition that rusfertide potentially treats a life-threatening, severe condition. With the designation comes a quicker FDA review time.

According to the National Organization for Rare Disorders, patients with PV may develop an enlarged spleen, blood clots, fatigue or dizziness. All patients demonstrate thickened blood at an increased volume, termed hyperviscosity. This condition can impede the way blood circulates around the body, inducing a range of secondary issues. PV affects primarily men that are over the age of 60. Roughly 50 per 100,000 people in the U.S. are diagnosed with PV. Rusfertide might be the treatment many have long waited for.