- Small cap CTI BioPharrma (NASDAQ:CTIC -22.7%) slumps on a 3x surge in volume in apparent response to its disclosure of data from the Phase 3 PERSIST-1 study assessing pacritinib in patients with primary or secondary myelofibrosis, a rare cancer of the bone marrow. The disclosure was made in the company's 10-K filed yesterday after the close.
- On March 9, CTI announced that PERSIST-1 met its primary efficacy endpoint in the intent-to-treat (ITT) population of the proportion of patients achieving a 35% reduction in spleen volume from baseline to Week 24 compared to best available therapy (BAT). In addition, the company stated that the data demonstrated a significant difference between patients with platelet counts <100K per microliter and those with <50K per microliter, subgroups that were stratified at randomization. The actual numbers were not disclosed, however.
- In the 10-K, page seven, there is a table of data from the trial. The proportion of patients in the ITT population who achieved at least a 35% reduction in spleen volume at from baseline to Week 24 was 23.6% (52/220) compared to 4.7% (5/107) for BAT (p<0.0001). This group included patients who responded before Week 24. At Week 24, though, the proportion of patients achieving at least a 35% reduction in spleen volume dropped to 19.1% (n=42/220) compared to the same 4.7% for BAT (n=5/107) (p=0.0003), showing a loss of ten responders. This implies that pacritinib's therapeutic effect failed to persist, but the reason could have been that the ten patients did not have an MRI scan at Week 24, which would have changed their status to non-responder.