ASCO: CTI's myelofibrosis drug pacritinib posts competitive PhIII data

CHICAGO--CTI BioPharma and its partner Baxter ($BAX) outlined positive Phase III data for their myelofibrosis drug pacritinib, which may help pave a way to position the therapy against Jakafi next year.

The biotech already reported that the Phase III was successful in hitting its primary endpoint: A 35% or greater reduction in spleen volume in the drug arm of the 327-patient study. But on Saturday, CTI ($CTIC) added at ASCO that some of the patients in subgroups with low-platelet counts also benefited from the drug, opening up a marketing pitch for patients whose platelet counts are too low for a high dose of Incyte's ($INCY) Jakafi.

For patients with platelet counts below 100,000 16.7% had a significant drop in spleen volume, with 22.9% in the 50,000-or-below group also responding to the drug. For all groups the response rate for pacritinib was 19.1% compared with 4.7% in the comparison arm. None of the patients in the comparison arm of either of the two low-platelet subgroups, which received best alternative care aside from a JAK inhibitor, responded similarly.

"Both pacritinib and ruxolitinib (Jakafi) will have roles" in myelofibrosis, The Mayo Clinic's Dr. Ruben Mesa, the lead investigator in the pacritinib study, told Adam Feuerstein at TheStreet. "Blood count of patients is likely to be an important decision-making factor for doctors" when choosing between the two drugs, he adds.

Feuerstein goes on to note that myelofibrosis patients with low platelet counts may either have to forego Jakafi or settle for a low dose. And pacritinib also helped with anemia among some patients, another distinguishing factor that could help the drug, provided the next late-stage study for this therapy also comes in with positive final data.

CTI got $60 million upfront and a promise of $112 million in development milestones from Baxter back in the fall of 2013 for their partnership, gaining some badly needed credibility for itself after the FDA scorned pixantrone and the biotech's failed attempt to win an approval for lymphoma.

That history has spurred considerable caution about claims of success from the company, with many analysts waiting to see final data before drawing any conclusions about the drug's market potential.

- here's the release