Deciphera Pharmaceuticals, Inc. announced four poster presentations at the upcoming 2023 American Society of Clinical Oncology (ASCO) Annual Meeting, being held in Chicago, Illinois on June 2-6, 2023. Abstract Number: TPS11582; Title: INSIGHT: A phase 3, randomized, multicenter, open-label study of ripretinib vs sunitinib in patients with advanced gastrointestinal stromal tumor previously treated with imatinib harboring KIT exon 11 + 17 and/or 18 mutations. Presenter: Suzanne George, M.D., Associate Division Chief, Sarcoma Center, Dana-Farber Cancer Institute; Session Date: June 3; Session Time: 1:15 – 4:15 PM CT; Key Highlights: INSIGHT is an international, Phase 3, randomized, multicenter, open-label study to evaluate the efficacy of ripretinib vs.

sunitinib in patients with advanced GIST previously treated with imatinib and who have KIT exon 11 mutations and co-occurring mutations exclusively in KIT exon 17 and/or 18 54 participants will be randomized 2:1 to either ripretinib 150 mg once daily (QD; continuous) or sunitinib 50 mg QD (4 weeks on/2 weeks off) in 6-week cycles; Patients will receive the study drug until disease progression determined by independent radiologic review (IRR) using modified Response Evaluation Criteria in Solid Tumors version 1.1 (mRECIST v.1.1), unacceptable toxicity, or withdrawal of consent; Upon disease progression as determined by blinded IRR, patients in the sunitinib arm may crossover to receive ripretinib; The primary outcome measure is progression-free survival based on blinded IRR. Abstract Number: 397784; Title: Mutational heterogeneity of imatinib resistance and efficacy of ripretinib vs sunitinib in patients with gastrointestinal stromal tumor: ctDNA analysis from INTRIGUE; Presenter: Sebastian Bauer, M.D., Head of Sarcoma Center and Translational Sarcoma Research at the West German Cancer Center, University Hospital Essen, University Duisburg-Essen and German Cancer Consortium; Session Date: June 3; Presentation Time: 1:54 – 2:00 PM CT; Key Highlights: In patients with a KIT exon 11 primary mutation identified by the planned exploratory analysis from INTRIGUE: 52 patients had additional mutations in KIT exon 17/18 only; 41 patients had additional mutations in KIT exon 13/14 only; 22 patients had additional mutations in both KIT exon 13/14 and exon 17/18; Patients with mutations in KIT exon 11 and exon 17/18 only derived substantially improved clinical benefit with ripretinib compared to sunitinib; Ripretinib demonstrated a median PFS (mPFS) of 14.2 months compared to 1.5 months for the sunitinib arm (HR 0.22, nominal P <0.0001); Ripretinib demonstrated a confirmed objective response rate (ORR) of 44.4% (n=12 of 27) compared to 0% for sunitinib (nominal P = 0.0001); OS for the ripretinib arm has not reached a median, while patients randomized to the sunitinib arm had a median OS (mOS) of 17.5 months (HR 0.34, nominal P = 0.0061); Patients with mutations in KIT exon 11 and 13/14 only derived substantially improved clinical benefit with sunitinib compared to ripretinib; Ripretinib demonstrated an mPFS of 4.0 months compared to 15.0 months for the sunitinib arm (HR 3.94, nominal P = 0.0005); Ripretinib demonstrated a confirmed ORR of 9.5% compared to 15% for sunitinib (nominal P = 0.5922); Ripretinib demonstrated a mOS of 24.5 months, while mOS for patients randomized to sunitinib was not estimable (HR 1.75, nominal P = 0.2085). The planned INSIGHT Phase 3 clinical study is a randomized, global, multicenter, open-label study to evaluate the efficacy and safety of QINLOCK compared to sunitinib in patients with GIST previously treated with imatinib with mutations in KIT exon 11 and 17/18 only (excluding patients with mutations in KIT exons 9, 13, or 14).

In the study, 54 patients will be randomized 2:1 to either QINLOCK 150 mg once daily or sunitinib 50 mg once daily for four weeks followed by two weeks without sunitinib. The primary endpoint is PFS as determined by independent radiologic review using modified RECIST 1.1 criteria. Secondary endpoints include ORR as determined by independent radiologic review using modified RECIST 1.1 criteria and OS.