Why Did Deciphera Stock Plunge 70% Today?

Deciphera Pharmaceuticals Inc DCPH stock plunged to a 52-week after announcing disappointing results from the INTRIGUE Phase 3 study of Qinlock in patients with gastrointestinal stromal tumor (GIST) previously treated with Novartis AG's NVS Gleevec (imatinib).
The study did not meet the primary endpoint of improved progression-free survival (PFS) compared with the standard of care Pfizer Inc's PFE Sutent (sunitinib).
The full results from the INTRIGUE Phase 3 clinical study will be presented at an upcoming medical meeting.
In the study, 453 patients were randomized 1:1 to either Qinlock 150 mg once daily or sunitinib 50 mg once daily for four weeks, followed by two weeks without sunitinib.
The study did not achieve the primary efficacy endpoint of progression-free survival (PFS).
In patients with a KIT exon 11 primary mutation (n=327), Qinlock demonstrated a median PFS (mPFS) of 8.3 months compared to 7.0 months for the sunitinib arm.
Although not formally tested due to the rules of the hierarchical testing sequence, in the all patient intent-to-treat (AP) population, Qinlock demonstrated an mPFS of 8.0 months compared to 8.3 months for the sunitinib arm.
Price Action: DCPH shares are down 71.6% at $10.24 during the premarket session on the last check Friday.