Struggling CTI reveals new pacritinib data, misses a primary endpoint

CTI BioPharma ($CTIC), still under a clinical hold enforced by the FDA back in February for its investigational JAK2 inhibitor candidate pacritinib, has posted new data from its PERSIST-2 trial showing it hit one primary endpoint, but missed another.

It was in fact this study that at the start of the year prompted the U.S. regulator to slap a full clinical hold on the biotech, halting dosing and persuading CTI to yank its newly completed drug application, given the high level of adverse events and deaths from the test.

The biotech had been given a fast-track status by the FDA in 2014, but the deaths in PERSIST-2 in pacritinib-treated patients, which included intracranial hemorrhage, cardiac failure and cardiac arrest, alarmed the FDA so greatly it said it could not allow its continuance.

The regulator recommended back in February that the biotech conduct dose exploration studies for pacritinib in patients with myelofibrosis, and submit final study reports and datasets for its two studies PERSIST-1 and PERSIST-2.

Today, it has posted some new data for the drug, which is partnered with Baxalta (now Shire) from PERSIST-2. This Phase III trial compared pacritinib, an oral multikinase inhibitor, with other available therapies such as Novartis’ ($NVS) Jakavi (ruxolitinib), for patients with myelofibrosis whose platelet counts are less than 100,000 per microliter--a patient population with high-risk advanced disease.

Just over 300 patients were enrolled in the study, which formed the basis for the safety analysis, according to the biotech, but only 221 patients reached week 24 (the primary analysis time point) before the clinical hold was imposed.

CTI said that its preliminary results showed from these patients that the PERSIST-2 trial met one of the co-primary endpoints, showing a statistically significant response rate in spleen volume reduction in patients with myelofibrosis treated with pacritinib compared to JAK2 inhibitor Jakavi.

But it did however fail to meet its other co-primary endpoint, of greater than 50% reduction in total symptom score.

The biotech said that the most common treatment emergent adverse events for pacritinib were “generally manageable diarrhea, nausea and vomiting.”

The incidence of cardiac and bleeding adverse events (all grades and grade 3-4 including deaths) were similar across the arms, it added, with overall mortality rates “comparable between arms.”

Additional data from ongoing analyses along with top-line results from PERSIST-2 are slated to be posted at an upcoming scientific meeting.

“Having analyzed data from two Phase III trials with the only JAK inhibitor to be studied in severely thrombocytopenic patients, including patients on JAK2 therapy or those who failed prior JAK2, we are encouraged by pacritinib's clinical profile in this difficult-to-treat group of patients with myelofibrosis,” said James Bianco, president and CEO of CTI BioPharma.

“We are grateful for the support and commitment of the investigators, our steering committee and, most importantly, all the patients who participated in PERSIST-2.” Despite the upbeat tone, the clinical hold still remains on the biotech.  

The biotech was marginally up 1.45% at the end of play Friday, before the data were posted, but is still locked in penny-stock territory with shares trading at 35 cents and with a market cap of just $100 million.