Deciphera Pharmaceuticals, Inc. announced the presentation of results from the INTRIGUE Phase 3 study of QINLOCK (ripretinib) in patients with gastrointestinal stromal tumor (GIST) previously treated with imatinib at the American Society of Clinical Oncology (ASCO) Plenary Series Session. The presentation, which follows the announcement in November 2021 of the top-line results, is titled “INTRIGUE: A phase III, randomized, open-label study to evaluate the efficacy and safety of ripretinib vs sunitinib in patients with advanced gastrointestinal stromal tumor previously treated with imatinib” and is available on the Company's website at www.deciphera.com/presentations-publications. ASCO will be hosting a livestream event on Tuesday, January 25, 2022 at 3:00 PM ET featuring presentation of the abstract by Michael Heinrich, M.D., FACP, Professor of Medicine at Oregon Health & Science University followed by a discussion of the abstract by George D. Demetri, M.D., FASCO, FACP, Dana-Farber Cancer Institute, as well as a panel discussion with Drs.

Heinrich and Demetri and Vicki Keedy, M.D., MSCI, Vanderbilt University Medical Center. To participate in the free and open session participants may register and login at https://www.asco.org/meetings-education/monthly-plenary-series/program. In patients with GIST who progressed on or were intolerant to imatinib, the efficacy of QINLOCK and sunitinib were comparable, although progression-free survival (PFS) of QINLOCK as determined by independent radiologic review using modified Response Evaluation Criteria in Solid Tumors (RECIST) did not meet the study's primary endpoint of superiority compared to sunitinib.

The statistical analysis plan included a hierarchical testing sequence that included evaluation of patients with a KIT exon 11 primary mutation (Exon 11) and then of the all patient (AP) population. Key highlights from the study presented January 24, 2022 include the following: An international, multicenter study conducted in 122 active sites across 22 countries, 453 patients were randomized to ripretinib (n = 226; Exon 11, n = 163) or sunitinib (n = 227; Exon 11, n = 164); In patients with a KIT exon 11 primary mutation, ripretinib demonstrated a median PFS (mPFS) of 8.3 months compared to 7.0 months for the sunitinib arm (Hazard Ratio [HR] 0.88, p=0.36). In the AP population (n=453), ripretinib demonstrated an mPFS of 8.0 months compared to 8.3 months for the sunitinib arm (HR 1.05, nominal p value=0.72); In patients with a KIT exon 11 primary mutation, ripretinib demonstrated an objective response rate (ORR) of 23.9% (n=39 of 163) compared to 14.6% (n=24 of 164) for sunitinib (nominal p value=0.03).

In the AP population ripretinib demonstrated an ORR 21.7% (n=49 of 226) compared to 17.6% (n=40 of 227) for sunitinib (nominal p value=0.27); Ripretinib was generally well tolerated. Fewer patients in the ripretinib arm experienced Grade 3-4 treatment-emergent adverse events compared to sunitinib (41.3% vs 65.6%); Patients receiving sunitinib were three times more likely to develop Grade 3 hypertension compared to patients receiving ripretinib (26.7% vs. 8.5%) and patients receiving sunitinib were seven times more likely to develop Grade 3 palmar-plantar erythrodysesthesia compared to patients receiving ripretinib (10.0% vs.

1.3%); Patient reported outcome measures also showed a more favorable tolerability profile for patients receiving ripretinib compared to patients receiving sunitinib. Patients receiving ripretinib experienced less deterioration in their ability to engage in either work or leisure activities during treatment and fewer patients receiving ripretinib experienced moderate to extremely large impact on their lives due to skin toxicity across treatment cycles compared to patients receiving sunitinib.